Announcement of Preliminary Regulatory Determinations for Contaminants on the Third Drinking Water Contaminant Candidate List
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Request for public comment.
CFR Part: "40 CFR Part 141"
Citation: "79 FR 62716"
Document Number: "EPA-HQ-OW-2012-0155; FRL-9917-87-OW"
Page Number: "62716"
"Proposed Rules"
SUMMARY: The Safe Drinking Water Act (SDWA), as amended in 1996, requires the
EFFECTIVE DATE: Comments must be received on or before
ADDRESSES: Submit your comments, identified by Docket ID No. EPA-HQ-OW-2012-0155, by one of the following methods:
* www.regulations.gov: Follow the online instructions for submitting comments.
* Mail: Water Docket,
* Hand Delivery: EPA Docket Center, [
Instructions: Direct your comments to Docket ID No. EPA-HQ-OW-2012-0155.
Docket: All documents in the docket are listed in the www.regulations.gov index. Although listed in the index, some information is not publicly available, e.g., CBI or other information whose disclosure is restricted by statute. Certain other material, such as copyrighted material, will be publicly available only in hard copy. Publicly available docket materials are available either electronically in www.regulations.gov or in hard copy at the Water Docket,
FOR FURTHER INFORMATION CONTACT:
SUPPLEMENTARY INFORMATION:
I. General Information
A. Does this action apply to me?
Neither these preliminary regulatory determinations nor the final regulatory determinations, when published, impose any requirements on anyone. Instead, this action notifies interested parties of
B. Tips for Preparing Your Comments
When submitting comments, remember to:
* Identify the rulemaking by docket number and other identifying information (subject heading,
* Explain why you agree or disagree and suggest alternatives.
* Describe any assumptions and provide any technical information and/or data that you used.
* Provide specific examples to illustrate your concerns, and suggest alternatives.
* Explain your views as clearly as possible.
* Make sure to submit your comments by the comment period deadline identified.</p>
Abbreviations Used in This Document Abbreviation Meaning [mu]g/L Micrograms per liter. ADAF Age Dependent Adjustment Factor. AM Assessment Monitoring. AMWAAssociation of Metropolitan Water Agencies . ATSDRAgency For Toxic Substances And Disease Registry . AWWAAmerican Water Works Association . BATs Best Available Technologies. BMD Benchmark Dose. BMDL Benchmark Dose (95% Lower Confidence Bound). BW Body Weight.CARC Cancer Assessment Peer Review Committee. CAS Chemical Abstracts Service. CASRN Chemical Abstract Service Registry Number. CBI Confidential Business Information. CCL Contaminant Candidate List. CCL 1 First Contaminant Candidate List. CCL 2 Second Contaminant Candidate List. CCL 3 Third Contaminant Candidate List. CCR Consumer Confidence Report. CFR Code of Federal Regulations. ChE Cholinesterase. CMR Chemical Monitoring Reform. CSF Cancer Slope Factor. CUSIUR Chemical Update System/Inventory Update Rule. cVOC Carcinogenic Volatile Organic Compounds. CW Concentration in Water. CWS Community Water System. CWSSCommunity Water System Survey . DBP Disinfection Byproduct. DBP ICR Disinfection Byproduct Information Collection Rule. DDE 1,1-Dichloro-2,2-bis(p-chlorophenyl)ethylene. DSMRT Distribution System Maximum Residence Time. DWI Drinking Water Intake. DWS Drinking Water Strategy. EFSAEuropean Food Safety Authority . ELCD Electrolytic Conductivity Detection.EPA Environmental Protection Agency . EPCRA Emergency Planning And Community Right-To-Know Act. EPTC S-Ethyl propylthiocarbamate. EPTDSEntry Point to the Distribution System. ESA Ethanesulfonic Acid. EWGEnvironmental Working Group . F Fraction of a 70 year lifetime applicable to the age period. FFQ Food Frequency Questionnaire. FIFRA Federal Insecticide, Fungicide, And Rodenticide Act. FRFederal Register . GAC Granular Activated Carbon. GAOGovernment Accountability Office . GC Gas Chromatography. GW Ground Water. HA Health Advisory. HRL Health Reference Level. ICR Information Collection Rule. IOC Inorganic Compound. IREDs Interim Eligibility Decisions. IRIS Integrated Risk Information System. Kg Kilogram. LOAEL Lowest Observed Adverse Effect Level. MCLG Maximum Contaminant Level Goal. MDL Method Detection Limit. mg/L Milligrams per liter. mg/kg/day Milligrams per kilogram per day. MDBP Microbial Disinfection Byproduct. MOA Mode of Action. MRL Minimum Reporting Limit. MS Mass Spectrometry. MTBE Methyl Tertiary Butyl Ether. NASNational Academy of Sciences . NAWQA National Water Quality Assessment. NCFAPNational Center for Food and Agricultural Policy . NCINational Cancer Institute . NCOD National Drinking Water Contaminant Occurrence Database. NDBA N-Nitroso-di-n-butylamine. NDEA N-Nitrosodiethylamine. NDMA N-Nitrosodimethylamine. NDPA N-Nitroso-di-n-propylamine. NDPhA N-Nitrosodiphenylamine. NDWACNational Drinking Water Advisory Council . NIRSNational Inorganics And Radionuclides Survey . NMEA N-Nitrosomethylethylamine. NOAEL No Observed Adverse Effect Level. NPDES National Pollutant Discharge Elimination System. NPDWR National Primary Drinking Water Regulation. NPYR N-Nitrosopyrrolidine. NRCNational Research Council . NREC National Reconnaissance of Emerging Contaminants. NTP National Toxicology Program. OA Oxanilic Acid. OPPOffice of Pesticides Program . OWOffice of Water . PCCL Preliminary Contaminant Candidate List. PCE Tetrachloroethylene. PDP Pesticide Data Program. PFOA Perfluorooctanoic Acid. PFOS Perfluorooctanesulfonic Acid. PHA Provisional Health Advisory. PID Photoionization Detection. PMP Pesticide Monitoring Program. PWS Public Water System. QA Quality Assurance. RD 1 Regulatory Determinations 1. RD 2 Regulatory Determinations 2. RD 3 Regulatory Determinations 3. RED Reregistration Eligibility Decision. RfD Reference Dose. RL Reporting Limit. RSC Relative Source Contribution. SAPScientific Advisory Panel . SDWA Safe Drinking Water Act. SEPWU.S. Senate Committee on Environment and Public Works . SSScreening Survey . SSCTs Small System Compliance Technologies. STORET Storage And Retrieval (STORET) Data System. SW Surface Water. SY Six Year Review. SY3 Six Year Review 3. TCE Trichloroethylene. TPTH Triphenyltin Hydroxide. TRED Tolerance Reassessment Progress And Risk Management Decision.TRI Toxic Release Inventory. TT Treatment Technique. UCM Unregulated Contaminant Monitoring. UCMR 1 First Unregulated Contaminant Monitoring Regulation. UCMR 2 Second Unregulated Contaminant Monitoring Regulation. UCMR 3 Third Unregulated Contaminant Monitoring Regulation. UF Uncertainty Factor.USDA United States Department of Agriculture . USGSUnited States Geological Survey . VOC Volatile Organic Compound. WHOWorld Health Organization .
Table of Contents
I. General Information
A. Does this action apply to me?
B. Tips for Preparing Your Comments
II. Purpose and Background
A. What is the purpose of this action?
B. Background on the CCL and Regulatory Determinations
1. Statutory Requirements for CCL and Regulatory Determinations
2. The First Contaminant Candidate List (CCL 1) and Regulatory Determinations (RD 1)
3. The Second Contaminant Candidate List (CCL 2) and Regulatory Determinations (RD 2)
4. The Third Contaminant Candidate List (CCL 3) and Regulatory Determinations (RD 3)
5. The Drinking Water Strategy
6. Outreach for RD 3 (Stakeholder Meeting and Expert Review)
III. Approach and Overall Outcome for RD 3
A. Summary of the Approach and Overall Outcome for RD 3
1. Phase 1 (Data Availability Phase)
2. Phase 2 (Data Evaluation Phase)
3. Phase 3 (Regulatory Determination Assessment Phase)
B. Supporting Documentation for
C. Analyses Used To Support the Preliminary Regulatory Determinations
1. Evaluation of Adverse Health Effects
2. Evaluation of Contaminant Occurrence and Exposure
IV. Contaminant-Specific Discussions for the RD 3 Preliminary Regulatory Determinations
A. Summary of the Preliminary Regulatory Determination
B. Contaminant Profiles
1. Dimethoate
2. 1,3-Dinitrobenzene
3. Strontium
4-5. Terbufos and Terbufos Sulfone
V. What is the status of the agency's evaluation of chlorate and the nitrosamines?
VI. What about the remaining CCL 3 contaminants?
VII.
VIII. References
Appendix: HRL Derivation with Age-Related Exposure Factors
II. Purpose and Background
This section briefly summarizes the purpose of this action, the statutory requirements, and previous activities related to the CCL and regulatory determinations.
A. What is the purpose of this action?
The purpose of this action is to present and request comment on
B. Background on the CCL and Regulatory Determinations
1. Statutory Requirements for CCL and Regulatory Determinations. Section 1412(b)(1)(B)(i) of the 1996 Safe Drinking Water Act Amendments (SDWA) requires
(a) The contaminant may have an adverse effect on the health of persons;
(b) the contaminant is known to occur or there is substantial likelihood that the contaminant will occur in public water systems with a frequency and at levels of public health concern; and
(c) in the sole judgment of the Administrator, regulation of such contaminant presents a meaningful opportunity for health risk reduction for persons served by public water systems.
If EPA determines that these three statutory criteria are met and makes a final determination to regulate a contaminant, the agency has 24 months to publish a proposed Maximum Contaminant Level Goal /1/ (MCLG) and NPDWR. /2/ After the proposal, the agency has 18 months to publish and promulgate a final MCLG and NPDWR (SDWA section 1412(b)(1)(E)). /3/
FOOTNOTE 1 The MCLG is the "maximum level of a contaminant in drinking water at which no known or anticipated adverse effect on the health of persons would occur, and which allows an adequate margin of safety. Maximum contaminant level goals are non-enforceable health goals." (40 CFR 141.2; 42 U.S.C. 300g-1) END FOOTNOTE
FOOTNOTE 2 An NPDWR is a legally enforceable standard that applies to public water systems. An NPDWR sets a legal limit (called a maximum contaminant level or MCL) or specifies a certain treatment technique (TT) for public water systems for a specific contaminant or group of contaminants. The MCL is the highest level of a contaminant that is allowed in drinking water and is set as close to the MCLG as feasible using the best available treatment technology and taking cost into consideration. END FOOTNOTE
FOOTNOTE 3 The statute authorizes a nine month extension of this promulgation date. END FOOTNOTE
2. The First Contaminant Candidate List (CCL 1) and Regulatory Determinations (RD 1).
FOOTNOTE 4 Consumer information about Acanthamoeba for people who wear contact lenses can be found at http://water.epa.gov/action/advisories/acanthamoeba/index.cfm. END FOOTNOTE
FOOTNOTE 5 The health advisories for CCL 1 can be found at http://water.epa.gov/drink/standards/hascience.cfm. END FOOTNOTE
3. The Second Contaminant Candidate List (CCL 2) and Regulatory Determinations (RD 2). The agency published the final CCL 2 in the FR on
FOOTNOTE 6 The health advisories for CCL 2 can be found at http://water.epa.gov/drink/standards/hascience.cfm. END FOOTNOTE
4. The Third Contaminant Candidate List (CCL 3) and Regulatory Determinations (RD 3). The agency published the final CCL 3, which listed 116 contaminants, in the FR on
(a) Identification of a broad universe of [approx.] 7,500 potential drinking water contaminants (the CCL 3 Universe);
(b) screening the CCL 3 Universe to a preliminary CCL (PCCL) of [approx.] 600 contaminants based on the potential to occur in PWSs and the potential for public health concern; and
(c) evaluation of the PCCL contaminants based on a more detailed review of the occurrence and health effects data to identify a final list of 116 CCL 3 contaminants.
The development of the CCL, regulatory determinations, and any subsequent rulemaking should be viewed as a progression where each process builds upon the previous process, including the collection of data and analyses conducted. The agency's improvements in developing CCL 3 provide an excellent foundation for RD 3 by enhancing
While this notice focuses on the preliminary regulatory determinations for 5 of the 116 CCL 3 contaminants, it is important to note that the agency made and published a final determination to regulate one CCL 3 contaminant, perchlorate, on
5. The Drinking Water Strategy. In
FOOTNOTE 7 More information about the DWS can be found at water.epa.gov/lawsregs/rulesregs/sdwa/dwstrategy/. END FOOTNOTE
(a) Address contaminants as groups rather than one at a time so that enhancement of drinking water protection can be achieved cost-effectively.
(b) Foster development of new drinking water technologies to address health risks posed by a broad array of contaminants.
(c) Use the authority of multiple statutes to help protect drinking water.
(d) Partner with States to develop shared access to all PWSs monitoring data.
The first principle (i.e., addressing contaminants as groups) has a direct bearing on RD 3 and how to designate the contaminants for analysis, determination and subsequent regulation; that is, should they be considered individually or as a group. Although the agency has previously regulated contaminants as groups (e.g., total trihalomethanes, total haloacetic acids, gross alpha radionuclides, gross beta and photon emitters, etc.), all of the determinations for RD 1 and RD 2 were made on individual contaminants. As part of the DWS, the agency identified several factors to evaluate which contaminants might effectively be regulated as a group and considered these factors in evaluating contaminant groups for RD 3. All the factors do not have to be met, but the more factors that are met, the more suitable it may be to regulate the contaminants as a group. These factors include whether the contaminants in the group:
(a) Have a similar health endpoint,
(b) can be measured by the same analytical methods,
(c) can be treated using the same technology or treatment technique approach and/or
(d) have been shown to occur individually (and possibly co-occur if data are available).
EPA conducted extensive national outreach to solicit input from stakeholders on the DWS and how best to address groups of contaminants. Stakeholders generally agreed that while public health protection is of paramount importance, the grouping factors previously listed were some of the other important factors to consider in evaluating which contaminants would work best in a group regulation. Several CCL 3 contaminants (as well as non-CCL 3 contaminants) belong to contaminant groups that underwent consideration for regulation during the RD 3 process.
In
FOOTNOTE 8 http://water.epa.gov/lawsregs/rulesregs/sdwa/dwstrategy/. END FOOTNOTE
The SDWA requires
6. Outreach for RD 3 (Stakeholder Meetings and Expert Review).
EPA sought external advice and expert input for RD 3 by convening two public stakeholder meetings and conducting an Expert Review panel. On
FOOTNOTE 9 Subsequent to the
In
FOOTNOTE 10
FOOTNOTE 11 Under the statute, SDWA criterion 3 of Section 1412(b)(1)(A) is solely the Administrator's decision. END FOOTNOTE
To implement the commitment,
III. Approach and Overall Outcome for RD 3
This section describes (a) the approach
A. Summary of the Approach and Overall Outcome for RD 3
The three phases of the RD 3 Process are (1) the Data Availability Phase, (2) the Data Evaluation Phase, and (3) the Regulatory Determination Assessment Phase. Figure 1 provides a brief overview of the process
See Illustration in Original Document.
1. Phase 1 (Data Availability Phase)
In Phase 1, the Data Availability Phase, the agency identifies contaminants that may have sufficient health and occurrence data to proceed to Phase 2 and be listed on a "short list" for further evaluation. With regard to sufficient health effects data used to identify potential adverse health effect(s), the agency considers whether a peer-reviewed health risk assessment is available or in process from one of the following sources: (a) The agency's Integrated Risk Information System (IRIS); (b) the agency's
In regard to sufficient occurrence data, the agency considers the availability of nationally representative finished water data and whether other finished water data are available that indicate known and/or likely occurrence in PWSs. Occurrence data from the following sources, administered or overseen by
If nationally representative data are not available,
FOOTNOTE 12 These may be assessments that are geographically distributed across the nation but not intended to be statistically representative of the nation. Examples include
EPA prefers to have nationally representative data available when making regulatory determinations but may also use these other sources of finished water occurrence data to evaluate the contaminant and determine if there is "substantial likelihood that the contaminant will occur in PWSs with a frequency and at levels of public health concern." If there is sufficient occurrence in these other finished water data sources,
EPA also considers the availability of analytical methods for monitoring, and whether the contaminant is part of a contaminant group based on factors defined by the Drinking Water Strategy (DWS) (see section II.B.5). After conducting the health and occurrence data availability assessments, the agency identifies those contaminants and contaminant groups that meet the following Phase 1 data availability criteria:
(a) A peer-reviewed health assessment is available or in process, and
(b) A widely available analytical method for monitoring is available, and
(c) Either nationally representative finished water occurrence data are available, or other finished water occurrence data shows occurrence at levels >1/2 CCL 3 health reference level (HRL). /13/
FOOTNOTE 13 See section III.C for a discussion about how
If a contaminant meets these three criteria, it is placed on a "short list" and proceeds to Phase 2.
Table 1--Contaminants Proceeding From Phase 1 to Phase 2 1, 1, 1, 2-Tetrachloroethane *1 *3 Metolachlor oxanilic acid (OA). *1 *3 1, 2, 3-Trichloropropane *1 *3 Molinate. *1 1, 3-Dinitrobenzene *1 Molybdenum. *1 1, 4-Dioxane *2 Nitrobenzene. *1 *3 Acephate *2 N-Nitroso-di-n-butylamine (NDBA). *1 *3 *5 Acetochlor *1 *3 N-Nitrosodiethylamine (NDEA). *1 *3 Acetochlor ethanesulfonic acid (ESA) N-Nitrosodimethylamine (NDMA). *1 *3 *1 *3 Acetochlor oxanilic acid (OA) *1 *3 N-Nitroso-di-n-propylamine (NDPA). *1 *3 Alachlor ethanesulfonic acid (ESA) *1 N-Nitrosodiphenylamine (NDPhA). *3 *3 Alachlor oxanilic acid (OA) *1 *3 N-Nitrosomethylethylamine (NMEA). *1 *3 *5 Chlorate *2 N-Nitrosopyrrolidine (NPYR). *1 *3 Cobalt *1 Perfluorooctanesulfonic acid (PFOS). *2 Dimethoate *1 Perfluorooctanoic acid (PFOA). *2 Disulfoton *4 RDX. *1 Diuron *4 Strontium. *1 Methyl bromide (Bromomethane) *1 Terbufos. *2 *3 Methyl tert-butyl ether *1 Terbufos sulfone. *1 *3 Metolachlor *1 *3 Vanadium. *1 Metolachlor ethanesulfonic acid (ESA) *1 n3 *1 Has nationally representative finished water data and available or in process health assessment. *2 Has other finished water data (occurrence at levels > 1/2 CCL 3 HRL) and available or in process health assessment. *3 Component of a contaminant group and will be further evaluated in Phase 2. *4 One exception to the criterion of having available nationally representative drinking water data applies to contaminants monitored in the UCMR 1Screening Survey (SS). As noted in section 5, the UCMR 1 SS is a statistically defined, national sample of 300 PWSs. Because this survey only includes 300 systems, the agency identified and compiled additional supplemental data to compliment the UCMR 1 SS data for these contaminants that proceed to Phase 2 for further evaluation. *5 A non-CCL 3 contaminant that is part of the nitrosamine group.
The remaining 81 CCL 3 contaminants (listed in Table 2) did not meet either or both of the Phase 1 data availability criteria above and were not considered further for RD 3. GOES
Table 2--Contaminants Not Proceeding From Phase 1 to Phase 2 Has nationally representative finished water data but no health assessment 1,1-Dichloroethane Halon 1011 (Bromochloromethane). 3-Hydroxycarbofuran n-Propylbenzene. Chloromethane (Methyl chloride) sec-Butylbenzene. Germanium Tellurium. Has available or in process health assessment and other finished drinking water data but no occurrence at levels > 1/2 CCL 3 HRL 1-Butanol Formaldehyde. Acrolein Methamidophos. alpha-Hexachlorocyclohexane Oxydemeton-methyl. Bensulide Oxyfluorfen. Benzyl chloride Permethrin. Captan Profenofos. Dicrotophos Tebuconazole. Ethoprop Tribufos. Ethylene glycol Vinclozolin. Ethylene thiourea (Maneb) Ziram. Fenamiphos Has other finished drinking water data but no health assessment 17-alpha-Estradiol Estriol. Acetaldehyde Estrone. Aniline Ethinyl Estradiol (17-alpha-ethynyl estradiol). Butylated hydroxyanisole HCFC-22. Cyanotoxins (Anatoxin-a, Hexane. Cylindrospermopsin, Microcystin-LR) Equilenin Mestranol. Equilin Norethindrone (19-Norethisterone). Erythromycin Naegleria fowleri.* Estradiol (17-beta-Estradiol) Does not have nationally representative or other finished water data 1,3-Butadiene Quinoline. 2-Methoxyethanol Tebufenozide. 2-Propen-1-ol Thiodicarb. 4,4'-Methylenedianiline Thiophanate-methyl. Acetamide Toluene diisocyanate. Clethodim Triethylamine. Cumene hydroperoxide Triphenyltin hydroxide (TPTH). Dimethipin Urethane. Ethylene oxide Campylobacter jejuni. Hydrazine Escherichia coli (0157). Methanol Helicobacter pylori. Nitroglycerin Hepatitis A virus. N-Methyl-2-pyrrolidone Salmonella enteric. o-Toluidine Shigella sonnei. Oxirane, methyl- Does not have a widely available analytical method for occurrence monitoring Adenovirus Legionella pneumophila. Caliciviruses Mycobacterium avium. Enterovirus Not within scope of this RD 3 since regulatory determination made inFebruary 2011 Perchlorate * Does not have a widely available analytical method for occurrence monitoring.
2. Phase 2 (Data Evaluation Phase)
Contaminants that meet the minimum health and occurrence data availability requirements in Phase 1 are advanced to the Phase 2 evaluation. In addition to health and occurrence information data assessed in Phase 1, the agency collects additional health and occurrence data and more thoroughly evaluates this information to identify a list of contaminants that should proceed to Phase 3. The agency uses the following steps to develop this list: (a) Derive a draft HRL /14/ (See section III.C) for each contaminant, (b) compare all occurrence data against the draft HRL (along with the analytical method minimum reporting limit (MRL)), (c) identify contaminants that occur at levels and frequencies of public health concern, and (d) identify contaminants that have no or low occurrence at levels of public health concern.
FOOTNOTE 14 HRLs are not final determinations about the level of a contaminant in drinking water that is necessary to protect any particular population and are derived prior to development of a complete exposure assessment. HRLs are risk derived concentrations against which to evaluate the occurrence data to determine if contaminants occur at levels of potential public health concern. END FOOTNOTE
Using the available health effects assessments, the agency derives a draft HRL and then evaluates this HRL value (along with the analytical method MRL), against the concentration values compiled for the nationally representative or other finished water occurrence information identified in Phase 1. The agency also gathers additional occurrence data and information on monitoring in ambient or source water (relative to the draft HRL and the analytical method MRL), production, use, release to the environment, and persistence and mobility. In Phase 2, the agency specifically focuses its efforts to identify those contaminants or contaminant groups that are occurring or have substantial likelihood to occur at levels and frequencies of public health concern. To identify such contaminants, the agency considers the following information:
(a) How many samples (# and %) have detections > draft HRL and 1/2 draft HRL in the nationally representative and other finished water occurrence data?
(b) How many systems (# and %) have detections > draft HRL and 1/2 draft HRL in the nationally representative and other finished water occurrence data? and
(c) Is the contaminant associated with a contaminant group that is of public health concern and is being considered as part of the DWS? /15/
FOOTNOTE 15 Carcinogenic Volatile Organic Compounds (including 1,2,3-trichloropropane) are being evaluated in a separate regulatory effort. END FOOTNOTE
(d) Are there uncertainties or limitations with the data and/or analyses, such as the age of the dataset, limitation of the detection limit (i.e., MRL > draft HRL) and/or representativeness of the data (e.g., limited to a specific region) that may cause misestimation of occurrence in finished water at levels and frequency of public health concern?
After identifying contaminants that are occurring at levels and frequencies of public health concern to proceed to Phase 3, the agency evaluates the remaining contaminants on the "short list" to determine which contaminants have no or low occurrence at levels of health concern that could also proceed to Phase 3 by considering the following factors:
(a) Does the contaminant have nationally representative finished water data showing no or low # or % of detections > draft HRL? /16/
FOOTNOTE 16 Note that the non-national data tend to be limited in scope and
(b) If a contaminant has other finished water data in addition to nationally representative finished water data, does it support no or low potential for occurrence in drinking water?
(c) Does additional occurrence information of known quality support low or no occurrence or potential for occurrence in drinking water? For example, is the occurrence in ambient/source water at levels below the draft HRL? Are releases to the environment or use/production decreasing over time?
(d) There are no critical information/data gaps after evaluating the available health or occurrence data; and
(e) The contaminant is not included or evaluated with a group of contaminants based on the factors defined by the DWS.
After evaluating these factors and whether a contaminant appears to have sufficient data to evaluate the statutory criteria for regulatory determination, the agency determines if the contaminant should proceed to Phase 3. After evaluating the "short list" contaminants (listed in Table 1), the agency identified 10 CCL 3 contaminants and 2 non-CCL 3 contaminants (listed in Table 3) that were within one of the following Phase 2 data evaluation categories to proceed to Phase 3:
(a) A contaminant or part of a contaminant group occurring or likely to occur at levels and frequencies of public health concern, or
(b) A contaminant not occurring or likely to occur at levels and frequencies of public health concern and no data gaps. GOES
Table 3--Contaminants Proceeding From Phase 2 to Phase 3 Chlorate *1 *3 N-Nitrosodiethylamine (NDEA). *1 Dimethoate *2 N-Nitrosomethylethylamine (NMEA). *1 *4 1,3-Dinitrobenzene *2 N-Nitrosopyrrolidine (NPYR). *1 N-Nitroso-di-n-butylamine (NDBA) *1 Strontium. *1 *3 *4 N-Nitrosodimethylamine (NDMA) *1 Terbufos. *2 N-Nitroso-di-n-propylamine (NDPA) *1 Terbufos Sulfone. n2 *1 A contaminant or part of a contaminant group occurring or likely to occur at levels and frequencies of public health concern. *2 A contaminant not occurring or likely to occur at levels and frequencies of public health concern and no data gaps. *3 The UCMR 3 includes sampling at both the entry point to the distribution system (EPTDS) and distribution system maximum residence time (DSMRT) for this contaminant (77 FR 26071,May 2, 2012 ). For some contaminants, including disinfection byproducts and inorganics, occurrence values may differ between the EPTDS and the DSMRT due to dynamics within the distribution system such as contaminant degradation, formation, accumulation and release. *4 A non-CCL 3 contaminant that is part of the nitrosamine group.
Note that the agency does not have a threshold or a bright line for occurrence in drinking water that triggers whether a contaminant is of public health concern. There are a number of factors to consider in developing thresholds, some of which include the health effect(s), the potency of the contaminant, the level at which the contaminant is found in drinking water, how frequently the contaminant is found, the geographic distribution (national, regional, or local occurrence), other possible sources of exposure, and potential impacts on sensitive populations or lifestages, etc. Given the many possible combinations of factors and the constantly evolving science,
The remaining 25 CCL 3 contaminants (listed in Table 4) did not proceed to Phase 3 and were not considered for RD 3 because of one or more of the following critical health, occurrence, and/or other data gaps:
(a) An updated health assessment is needed, but was not completed by fall 2011;
(b) A health assessment is in process, but was not completed by fall 2011;
(c) Critical health effects gap (e.g., lack of data to support quantification for the oral route of exposure);
(d) Lacked nationally representative occurrence data;
(e) Insufficient other finished water occurrence data to demonstrate occurrence at levels and frequencies of public health concern (although it may have some levels of public health concern);
(f) Individual contaminants that were part of a group but lacked a widely available analytical method for occurrence monitoring; and
(g) Critical occurrence data gap (e.g., inconsistent results and/or trends in occurrence data, significant uncertainty in occurrence analyses and/or data).
Table 4 identifies the health, occurrence, and/or other data gaps that prevented the following 25 contaminants from moving forward for RD 3. The agency continues to conduct research, collect information or find other avenues to fill the data and information gaps identified in Table 4.
Table 4--Data and Rationale Summary of the 25 Contaminants Not Proceeding to Phase 3 No. Contaminant Health Occurrence Rationale data data available available 1 1,4-Dioxane Yes No *1 Occurrence data gaps (no nationally representative finished water data or sufficient other finished water data). 2 Acephate Yes No Occurrence data gaps (no nationally representative finished water data or sufficient other finished water data). 3 Acetochlor No Yes Health data gap (no health assessment for the degradates) and no detections in nationally representative finished water data. 4 Acetochlor No Yes Health data gap (no health ethanesulfonic acid assessment for the ESA (ESA) degradate) and no or low detections based on nationally representative finished water data. 5 Acetochlor oxanilic acid No Yes Health data gap (no health (OA) assessment for the OA degradate) and no or low detections based on nationally representative finished water data. 6 Alachlor ethanesulfonic No Yes Health data gap (no health acid (ESA) assessment for the ESA degradate) and no or low detections based on nationally representative finished water data. 7 Alachlor oxanilic acid No Yes Health data gap (no health (OA) assessment for the OA degradate) and no or low detections based on nationally representative finished water data. 8 Cobalt No Yes *2 Health data gap (health assessment not updated by fall 2011) and no detections in nationally representative or other finished water data at levels of public health concern. 9 Disulfoton Yes No Occurrence data gap (no nationally representative finished water data and no detections in other finished water data). 10 Diuron Yes No Occurrence data gap (no nationally representative finished water data and no detections in other finished water data). 11 Methyl Bromide No Yes *1 Health data gap (health assessment not updated by fall 2011). 12 Methyl tert-butyl ether No Yes Health data gap (IRIS health assessment not completed by fall 2011) and no or low detections based on nationally representative finished water data. 13 Metolachlor No Yes Health data gap (no health assessment for degradates) and few detections in nationally representative finished water data. 14 Metolachlor No Yes Health data gap (no health ethanesulfonic acid assessment for ESA (ESA) degradate) and no or low detections based on nationally representative finished water data. 15 Metolachlor oxanilic No Yes Health data gap (no health acid (OA) assessment for OA degradate) and no or low detections based on nationally representative finished water data. 16 Molinate No Yes Health data gap (OPP health assessment not completed by fall 2011 due to cancellation of molinate) and no detections in nationally representative or other finished water data at levels of public health concern. 17 Molybdenum No Yes Health data gap (health assessment not updated by fall 2011) and no detections in nationally representative or other finished water data at levels of public health concern. 18 N-Nitrosodiphenylamine Yes No Health data gap (health (NDPhA) assessment not updated by fall 2011) and occurrence data gaps (no EPA approved analytical method for monitoring). 19 Perfluorooctanesulfonic No No *1 Health data gap (health acid (PFOS) assessment not completed by fall 2011) and occurrence data gaps (limited other finished water data available). 20 Perfluorooctanoic acid No No *1 Health data gap (health (PFOA) assessment not completed by fall 2011) and occurrence data gaps (limited other finished water data available). 21 RDX No Yes Health data gap (IRIS health assessment not updated by fall 2011) and no detections in nationally representative or other finished water data at levels of public health concern. 22 Vanadium No Yes *2 Health data gap (health assessment not updated by fall 2011) and no to low detections in nationally representative finished water data at levels of public health concern. 23 1,1,1,2- Will be evaluated and Tetrachloroethane considered for the Carcinogenic Volatile Organic Compounds (cVOCs) group rule addressed in a separate process. 24 1,2,3-Trichloropropane ( *1) Will be evaluated and considered for the Carcinogenic Volatile Organic Compounds (cVOCs) group rule addressed in a separate process. 25 Nitrobenzene Will be evaluated and considered for the Carcinogenic Volatile Organic Compounds (cVOCs) group rule addressed in a separate process. *1 The UCMR 3 includes sampling at the EPTDS for this contaminant (77 FR 26071,May 2, 2012 ). *2 The UCMR 3 includes sampling at both the EPTDS and DSMRT for this contaminant (77 FR 26071,May 2, 2012 ). For some contaminants, including disinfection byproducts and inorganics, occurrence values may differ between the EPTDS and the DSMRT due to dynamics within the distribution system such as contaminant degradation, formation, accumulation and release.
3. Phase 3 (Regulatory Determination Assessment Phase)
Phase 3, the Regulatory Determination Assessments Phase, involves a complete evaluation of the statutory criteria for each contaminant or group of contaminants that proceed from Phase 2 and have sufficient information and data for making a regulatory determination. In this phase, the agency evaluates the following statutory criteria:
(a) Statutory Criterion #1--The contaminant may have an adverse effect on the health of persons. To evaluate statutory criterion #1,
(b) Statutory Criterion #2--The contaminant is known to occur or there is a substantial likelihood that the contaminant will occur in public water systems with a frequency and at levels of public health concern.
* How many samples (# and %) have detections > final HRL in the nationally representative and other finished water occurrence data?
* How many systems (# and %) have detections > final HRL in the nationally representative and other finished water occurrence data?
* Is the contaminant associated with a contaminant group that is of public health concern and is being considered as part of the DWS?
* Is the geographic distribution of the contaminant occurrence national, regional, or localized?
* In addition to the number of systems, what type of systems does the contaminant occur in? Does the contaminant occur in large or small systems? Does the contaminant occur in surface or ground water systems?
* Are there significant uncertainties or limitations with the data and/or analyses, such as the age of the dataset, limitation of the detection limit (i.e., MRL > final HRL) and/or representativeness of the data (e.g., limited in scope to a specific region)?
Additional, less important factors that the agency considers when identifying contaminants or contaminant groups that are of public health concern also include:
* How many samples (# and %) have detections >1/2 final HRL /17/ in the nationally representative and other finished water occurrence data?
FOOTNOTE 17 Note that the 1/2 HRL threshold is based on a recommendation from the NDWAC working grouping that provided recommendations on the first regulatory determinations effort. (USEPA, 2000b) END FOOTNOTE
* How many systems (# and %) have detections >1/2 final HRL in the nationally representative and other finished water occurrence data?
* How many samples (# and %) have detections > final HRL and 1/2 final HRL in the ambient/source water occurrence data?
* How many monitoring sites (# and %) have detections > final HRL and 1/2 final HRL in the ambient/source water occurrence data?
* Are production and use trends for the contaminant increasing or decreasing?
* How many pounds are discharged annually to surface water and/or released to the environment?
* Do the environmental fate and transport parameters indicate that the contaminant would persist and/or be mobile in water?
* Are there other uncertainties or limitations with the data and/or analyses for these additional factors that should be considered?
* Is the contaminant introduced by water treatment processes (e.g., disinfection byproducts)?
If a contaminant is known to occur or substantially likely to occur at a frequency and level of health concern in public water systems based on the factors listed above, then the agency answers "yes" to the second statutory criterion.
(c) Statutory Criterion #3--In the sole judgment of the Administrator, regulation of the contaminant presents a meaningful opportunity for health risk reduction for persons served by public water systems.
* Based on the occurrence information for statutory criterion #2 (and the potential number of systems impacted), what is the national population exposed or served by systems with levels >/=; HRL and 1/2 HRL (provide actual and estimated # and %)?
* What is the nature of the health effect(s) identified in statutory criterion #1 and are there sensitive populations that may be impacted (either qualitative or quantitative /18/)?
FOOTNOTE 18 If appropriate and if available, the agency quantitatively takes into account exposure data applicable to sensitive populations or lifestages when deriving HRLs for regulatory determinations. When data is not available on sensitive populations, the derivation of the RfD typically includes an uncertainty factor to account for the weakness in the database. See section III.C.1. Sensitive populations are also qualitatively considered by providing national prevalence estimates for a particular sensitive population if available. END FOOTNOTE
* For non-carcinogens, are there other sources of exposure that should be considered (i.e., what is the relative source contribution)?
* What is the geographic distribution of occurrence (e.g., local, regional, national)?
* Are there any uncertainties and/or limitations in the health and occurrence information or analyses that should be considered?
* What other factors or other pieces of information should be considered that may have direct bearing on any decision to regulate the contaminant (e.g., treatment, analytical methods, /19/ etc.)?
FOOTNOTE 19 If the agency decides to regulate a contaminant, SDWA requires that
After evaluating these factors, if the Administrator determines that there is a meaningful opportunity to reduce risk by regulating the contaminant in drinking water, then the agency answers "yes" to the third statutory criterion.
If the agency answers "yes" to all three statutory criteria in Phase 3 for a particular contaminant, then the agency makes a "positive" preliminary determination and requests public comment.
If after the public comment period, the agency answers "yes" to all three statutory criteria, the agency then makes a "positive" final determination that regulation is necessary and proceeds to develop an MCLG and NPDWR. The agency has 24 months to publish a proposed MCLG and NPDWR and an additional 18 months to publish a final MCLG and promulgate a final NPDWR. It should be noted that this regulatory determination process is distinct from the more detailed analyses needed to develop a national primary drinking water regulation. Thus, a decision to regulate is the beginning of the agency's regulatory development process, not the end.
If a contaminant has sufficient information and the agency answers "no" to any of the three statutory criteria, based on the available data, then the agency considers making a "negative" determination that an NPDWR is not necessary for that contaminant at that time. The agency may decide to develop a Health Advisory (HA), which provides non-regulatory concentration values for drinking water contaminants at which adverse health effects are not anticipated to occur over specific exposure durations (one-day, ten-days, several years, and a lifetime). HAs serve as informal technical guidance to assist Federal, State, and local officials, and managers of public or community water systems (CWSs) in protecting public health when emergency spills or contamination situations occur.
While a negative determination is considered a final agency action for this round of regulatory determinations, the contaminant is reconsidered for inclusion on the next CCL. If new health or occurrence information becomes available on contaminants with negative regulatory determinations, the agency considers whether the contaminant(s) should be listed on the next CCL and further evaluated in the next regulatory determinations process.
Of the twelve contaminants that proceeded to Phase 3, the agency is not making preliminary regulatory determinations for seven contaminants at this time. The seven contaminants include chlorate and the six nitrosamines (i.e., NDBA, NDMA, NDPA, NDEA, NPYR, and NMEA). As discussed in section V, chlorate and the six nitrosamines are DBPs and the agency plans to consider these contaminants as part of the regulatory review of existing MDBP regulations. DBPs need to be evaluated collectively, because the potential exists that the control of one DBP could affect the concentrations of other DBPs or the necessary treatment. After evaluating the five remaining CCL 3 contaminants in Table 3 (i.e., dimethoate, 1,3-dinitrobenzene, strontium, terbufos, and terbufos sulfone) against the three SDWA criteria and considering the factors listed for each, the agency is making preliminary regulatory determinations for these five CCL 3 contaminants. Table 5 provides a summary of the five contaminants evaluated for Phase 3 and the preliminary regulatory determination outcome. The agency seeks comment on the preliminary determination to regulate one contaminant (i.e., strontium) and to not regulate the remaining four contaminants (i.e., dimethoate, 1,3-dinitrobenzene, terbufos, and terbufos sulfone). Section IV.B of this notice provides a more detailed summary of the information and the rationale used by the agency to reach its preliminary decisions for these five contaminants. GOES
Table 5--Contaminants Evaluated in Phase 3 and the Regulatory Determination Outcome No. RD 3 contaminants Preliminary determination outcome 1 Dimethoate Do not regulate. 2 1,3-Dinitrobenzene Do not regulate. 3 Strontium Regulate. 4 Terbufos Do not regulate. 5 Terbufos Sulfone Do not regulate.
B. Supporting Documentation for
For this action,
* The comprehensive regulatory support document entitled, "Regulatory Determination 3 Support Document" (USEPA, 2014b), summarizes the information and data on the physical and chemical properties, uses and environmental release, environmental fate, potential health effects, occurrence and exposure estimates, the preliminary determinations, and the agency's rationale for these determinations.
* A separate health effects support document for strontium, entitled "Health Effects Support Document for Strontium" (USEPA, 2014c), that addresses exposure from drinking water and other media, toxicokinetics, hazard identification, and dose-response assessment, and provides an overall characterization of the risk from drinking water containing strontium. For the contaminants with negative determinations, the agency refers the reader to the IRIS or OPP assessments for more detailed information regarding health effects (USEPA, 1990a, 1990b, 2003c). These documents serve as the basis for the health information provided in the regulatory support documents.
* A comprehensive technical occurrence support document for UCMR 2 entitled, "Occurrence Data from the Second Unregulated Contaminant Monitoring Rule (UCMR 2)" (USEPA, 2014d). This occurrence support document includes more detailed information about UCMR 2, how
* A comprehensive protocol document, entitled "Protocol for the Regulatory Determination 3" (USEPA, 2014a). This protocol document describes the approach implemented by the agency to evaluate 116 CCL 3 contaminants in a three phase process and select the contaminants for preliminary determinations for RD 3. The protocol underwent expert review and the comments received were addressed by the agency.
C. Analyses Used To Support the Preliminary Regulatory Determinations
Sections III.C.1 and 2 of this action outline the health effects and occurrence/exposure evaluation process
1. Evaluation of Adverse Health Effects
Section 1412(b)(1)(A)(i) of SDWA requires
In evaluating contaminants for regulatory determination, Section 1412 (b)(1)(C) of SDWA also requires the agency to consider among other factors of public health concern, the effect of such contaminants upon subgroups that comprise a meaningful portion of the general population "such as infants, children, pregnant women, the elderly, individuals with a history of serious illness, or other subpopulations" that are identifiable as being at greater risk of adverse health effects compared to the general population. If appropriate and if available, the agency quantitatively takes into account data from sensitive populations and lifestages when deriving HRLs for regulatory determinations.
There are two general approaches to the derivation of an HRL. One approach is used for chemicals that cause cancer and exhibit a linear response to dose and the other applies to non-carcinogens and carcinogens evaluated using a non-linear approach. The derivation of HRLs for carcinogens and non-carcinogens are described below.
a. Derivation of an HRL for Carcinogens
For those contaminants that are considered to be likely or probable human carcinogens by a mutagenic or unknown mode of action (MOA), the agency calculates a toxicity value that defines the relationship between dose and response (i.e., the cancer slope factor or CSF).
(1) MOA: Unknown
In cases where the data on the mode of action are lacking,
Unit Risk ([mu]g/L)1 = CSF x [(DWI x CW)/BW]
Where:
CSF = Cancer Slope Factor (mg/kg/day)-1
DWI = Drinking Water Intake for an adult, assumed to be 2 L/day (90th percentile)
CW = Unit risk concentration in drinking water of 0.001 mg/L (1 [mu]g/L)
BW = Body Weight for an adult, assumed to be 70 kilograms (kg)
The cancer HRL is the concentration of a contaminant in drinking water corresponding to an excess estimated lifetime cancer risk of one-in-a-million (1 x 10-6), calculated as follows:
HRL ([mu]g/L) = Risk Level of 10-6 / Unit Risk ([mu]g/L)-1
As noted above, HRLs are not final determinations about the level of a contaminant in drinking water that must not be exceeded to protect any particular population. Rather, HRLs are risk derived concentrations against which to evaluate the occurrence data during the RD process to determine if contaminants occur at levels of potential public health concern.
(2) MOA: Mutagenic
If the chemical has a mutagenic mode of action, low dose linear extrapolation is used to calculate the CSF as described in the preceding paragraph. The
Age-Adjusted Unit Risk ([mu]g/L)-1 = SIGMA(CSF x ADAF x DWI/BWR x CW x F)
Where:
CSF = Cancer Slope Factor (mg/kg/day)-1
ADAF = The Age Dependent Adjustment Factor for the age group birth to two-years (ADAF = 10), two years to sixteen years (ADAF = 3), and sixteen to seventy years (ADAF = 1)
DWI/BWR = Drinking Water Intake Body Weight Ratio (DWI/BWR) expressed as liters per kg body weight for the age-specific group (90th percentile, consumers only) /20/
FOOTNOTE 20 The drinking water intake values were derived from the data in the
CW = Unit risk concentration in drinking water of 0.001 mg/L (1 [mu]g/L)
F = The fraction of a 70 year lifetime applicable to the age period: 2/70 for birth to two years, 14/70 for two years to sixteen years and 54/70 for sixteen years to seventy years
The cancer HRL is the concentration of a contaminant in drinking water corresponding to an excess estimated lifetime cancer risk of one-in-a-million (1 x 10<-6), calculated as follows:
HRL ([mu]g/L) = Risk Level of 10-6 / Age-Adjusted Unit Risk ([mu]g/L)-1
The six nitrosamines discussed in section V had data available to classify them as known or likely human carcinogens with a mutagenic mode of action. Low-dose linear extrapolations and ADAFs were applied to all four of the CCL 3 nitrosamines: NDMA, NDPA, NDEA and NYPR, as well as the two non-CCL 3 nitrosamines, NMEA and NDBA. The five contaminants for which the agency is making preliminary regulatory determinations (dimethoate, 1,3-dinitrobenzene, strontium, terbufos and terbufos sulfone) are non-carcinogens and were therefore evaluated using the RfD approach (discussed in the following section).
b. Derivation of an HRL for Non-Carcinogens
EPA generally calculates a reference dose (RfD) for those chemicals considered to be non-carcinogenic or not likely to be carcinogenic to humans. An RfD is an estimate of a daily oral exposure to the human population (including sensitive populations or lifestages) that is likely to be without an appreciable risk of deleterious effects during a lifetime. The RfD can be derived from either a no-observed-adverse-effect level (NOAEL), a lowest-observed-adverse-effect level (LOAEL), or the 95% lower confidence bound on a benchmark dose (BMD), known as a BMDL, with uncertainty factors applied to reflect limitations of the data used. In addition, if the critical health endpoint has high quality data associated with exposure for a specific developmental group or period of sensitivity, age-specific drinking water intake to body weight ratio values from the Exposure Factors Handbook (USEPA, 2011e) may be included in deriving an HRL from the RfD.
The agency uses uncertainty factors (UFs) to address uncertainty resulting from incompleteness of the toxicological database (e.g., lacking sensitive population data). The individual UFs (usually applied as integers of one, three, or ten) are multiplied together and used to derive the RfD from experimental data. Individual UFs are intended to account for:
(1) Variation in sensitivity among the members of the human population (i.e., intraspecies variability);
(2) uncertainty in extrapolating animal data to humans (i.e., interspecies variability);
(3) uncertainty in extrapolating from data obtained in a study with less-than-lifetime exposure to lifetime exposure (i.e., extrapolating from subchronic to chronic exposure);
(4) uncertainty in extrapolating from an LOAEL rather than from an NOAEL; and/or(5) uncertainty associated with an incomplete database.
For chlorate, dimethoate, 1,3-dinitrobenzene, strontium, /21/ terbufos, and terbufos sulfone,
FOOTNOTE 21 Because the critical health endpoint had dose-response data associated with exposure during a specific period of sensitivity (i.e., sensitive population),
HRL (mg/L) = [(RfD x BW)/DWI] x RSC
Where:
RfD = Reference Dose (mg/kg-day)
BW = Body Weight for an adult, assumed to be 70 kilograms (kg); for a child, assumed to be 10 kg
DWI = Drinking Water Intake for an adult, assumed to be 2 L/day (90th percentile); for child, assumed to be 1L/day (90th percentile)
RSC = Relative Source Contribution, or the level of exposure believed to result from drinking water when compared to other sources (e.g., food, ambient air). In all cases, a 20% RSC is used for HRL derivation because (1) HRLs are developed prior to a complete exposure assessment and (2) 20% is the most conservative RSC used in the derivation of an MCLG for drinking water.
c. Sources of Data/Information for Health Effects
EPA uses the best available peer-reviewed data and analyses in evaluating adverse health effects. Peer-reviewed health-risk assessments are available for all chemicals considered for regulatory determinations from the agency's Integrated Risk Information System (IRIS) Program, /22/ the agency's
FOOTNOTE 22 IRIS is an electronic
FOOTNOTE 23 The OPP is required under the Federal Insecticide Fungicide and Rodenticide Act (FIFRA) to periodically review the health effects data on all registered pesticides and reregister them for continued use. The results of the reregistration analysis are published in the Reregistration Eligibility Decision (RED) documents. Copies of the REDs are located at the following EPA Web site (http://www.epa.gov/oppsrrd1/reregistration/status.htm). END FOOTNOTE
FOOTNOTE 24 ATSDR establishes oral minimal risk levels for non-neoplastic endpoints for acute (14 days or less), intermediate (15--364 days), and chronic (365 days or more) exposure durations. Minimal risk levels for oral chronic exposure are similar to
FOOTNOTE 25 WHO establishes a "guideline value", a drinking water concentration that uses different default assumptions than
The agency performs a literature search for studies published after the available health assessment is completed to determine if new information suggests a different outcome. The agency collects and evaluates any peer-reviewed publications identified through the literature search for their impact on the RfD and/or cancer assessment. In cases where the recent data indicate that a change to the existing RfD or cancer assessment is needed, the
Table 6--Sources and Dates of EPA Health Risk Assessments Chemical IRIS OPP RED OW Assessment (date) (date) (date) Dimethoate 2007 1,3-Dinitrobenzene 1988 *1 Strontium 1992 2012 Terbufos 2006 Terbufos Sulfone 2006 n2 *1 The agency also reviewed a non-EPA source (ATSDR, 1995) for 1,3-dinitrobenzene to corroborate the IRIS assessment. *2 The OPP RED for the parent compound (terbufos) was used.
As noted in section III.B,
2. Evaluation of Contaminant Occurrence and Exposure
EPA uses data from many sources to evaluate occurrence and exposure from drinking water contaminants. The following comprise the primary sources of finished drinking water occurrence data discussed in this
* the Unregulated Contaminant Monitoring Regulation (UCMR 1 and 2),
* the
* Disinfection Byproducts Information Collection Rule (DBP ICR).
Several of the primary sources of finished water occurrence data are designed to be statistically representative of the nation. These data sources include UCMR 1, UCMR 2, and NIRS. /26/ The DBP ICR is geographically distributed across the country and national in scope but is not intended to be statistically representative of the nation.
FOOTNOTE 26 NIRS is designed to be statistically representative of groundwater systems and does not include surface water systems. END FOOTNOTE
The agency also evaluates supplemental sources of information on occurrence in drinking water, occurrence in ambient and source water, and information on contaminant use and release to augment and compliment these primary sources of drinking water occurrence data. Section III.C.2.a. of this action provides a brief summary of the primary sources of finished water occurrence data, and sections III.C.2.b and II.C.2.c provide brief summary descriptions of some of the supplemental sources of occurrence information and/or data. These descriptions do not cover all the reports that
a. Primary Sources of Finished Drinking Water Occurrence Data
As previously mentioned, the primary national sources of the drinking water occurrence data discussed in this
(1) The Unregulated Contaminant Monitoring Regulation (UCMR 1 and UCMR 2)
The UCMR is currently
The UCMR was designed as a three-tiered approach for monitoring contaminants related to the availability of analytical methods and related analytical laboratory capacity. Assessment Monitoring (AM), the largest sampling tier, typically relies on analytical methods that are in common use in drinking water laboratories.
EPA designed the AM sampling frame to ensure that sample results would support a high level of confidence and a low margin of error (see USEPA, 1999 and 2001b, for UCMR design details). AM is required for all large PWSs, those serving more than 10,000 people (i.e., a census of all large systems) and a national statistically representative sample of 800 small PWSs, those serving 10,000 or fewer people (for a total sample of approximately 4,000 systems). PWSs that purchase 100% of their water were not required to participate.
Each system conducts UCMR assessment monitoring for one year (during the three-year monitoring period). The rules require quarterly monitoring for surface water systems and twice-a-year, six-month interval monitoring for ground water systems. At least one sampling event must occur during a specified vulnerable period. Differing sampling points within the PWS may be specified for each contaminant related to the contaminants source(s).
The objective of the UCMR sampling approach for small systems was to collect contaminant occurrence data from a statistically selected, nationally representative sample of small systems. The small system sample was stratified and population-weighted, and included some other sampling adjustments such as allocating a selection of at least two systems from each State for spatial coverage. The UCMR AM program includes systems from all 50 States, the
UCMR
As noted, in addition to AM, SS monitoring was required for contaminants. For UCMR 1, the SS was conducted at 300 PWSs (120 large and 180 small systems) selected at random from the pool of systems required to conduct AM. Samples from the 300 PWSs from throughout the nation provided approximately 2,300 analyses for each contaminant. While the statistical design of the SS is national in scope, the uncertainty in the results for contaminants that have low occurrence is relatively high. Therefore,
For the UCMR 2 SS,
As previously noted, the details of the occurrence data and the results or findings for each of the contaminants considered for regulatory determination is presented in Section IV.B, the contaminant profiles section, and is described in further detail in the support documents for the RD 3 process (USEPA, 2014a and 2014b). The national design, statistical sampling frame, any new analytical methods, and the data analysis approach for the UCMR program has been peer-reviewed at different stages of development (see, USEPA, 2001b, 2008c, 2014d, for example.)
(2)
EPA conducted the NIRS to provide a statistically representative sample of the national occurrence of 36 selected inorganic compounds (IOCs) and radionuclides in CWSs served by ground water. The sample was stratified by system size and 989 ground water CWSs were selected at random representing 49 States (all except
One limitation of the NIRS is a lack of occurrence data for surface water systems.
(3) Disinfection Byproducts Information Collection Rule (DBP ICR)
The DBP ICR (61 FR 24353,
The DBP ICR provided a census of the largest systems that serve the largest proportion of the population served by PWSs at that time. It has previously been vetted for use in regulatory development, and
b. Supplemental Sources of Finished Drinking and Ambient Water Occurrence Data
The agency evaluates several sources of supplemental information related to contaminant occurrence in finished water and ambient and source waters to augment the primary drinking water occurrence data. Some of these sources were part of other agency information gathering efforts or submitted to the agency in public comment or suggested by stakeholders during previous CCL and Regulatory Determination efforts. These supplemental data are useful to evaluate the likelihood of contaminant occurrence in drinking water and/or to more fully characterize a contaminant's presence in the environment and potentially in source water, and to evaluate any possible trends or spatial patterns that may need further review. The descriptions that follow do not cover all the reports that
(1) Individual States' Data
To support the second Six-Year Review of regulated contaminants (see USEPA, 2009b),
(2)
<p> EPA periodically conducts the CWSS to collect data on the financial and operating characteristics from a nationally representative sample of CWSs. As part of the CWSS, all systems serving more than 500,000 people receive the survey. In the 2000 and 2006 CWSS, these very large systems were asked questions about the occurrence and concentration of unregulated contaminants in their raw and finished water. The 2000 CWSS (USEPA, 2002a, 2002b) requested data from 83 very large CWSs and the 2006 CWSS (USEPA, 2009c, 2009d) requested data from 94 very large CWSs. Not all systems answered every question or provided complete information on the unregulated contaminants. Because reported results are incomplete, they are illustrative, not representative, and are only used as supplemental information.
(3)
Since 1991, the USDA PDP has gathered data on pesticide residues in food. In 2001 the program expanded to include sampling of pesticide residues in treated drinking water, and in 2004 some sampling of raw water was incorporated as well (
(4)
In 1999, USGS and
(5)
The USGS instituted the National Water Quality Assessment (NAWQA) program in 1991 to examine ambient water quality status and trends in
The NAWQA program has been designed in ten-year cycles to enable national coverage that can be used for trends and causal assessments. In the Cycle 1 monitoring period, which was conducted from 1991 through 2001, NAWQA collected data from over 6,400 surface water and 7,000 ground water sampling points. Cycle 2 monitoring covers the period from 2002 through 2012, with various design changes from Cycle 1 (see
EPA, with the cooperation of USGS, performed a summary analysis of all Cycle 1 water monitoring data for the CCL 3 and Regulatory Determination process. The surface water data consisted of stream samples; all surface water data were included in the
For RD 3,
For RD 3,
(6) Storage and Retrieval (STORET) Data System
EPA's STORET database contains raw biological, chemical, and physical data from surface and ground water sampling conducted by Federal, State and local agencies, Indian Tribes, volunteer groups, academics, and others. A wide variety of data relating to water quality from all 50 States as well as multiple territories and jurisdictions of
c. Supplemental Production, Use and Release Data
The agency reviews various sources of information to assess if there are changes or trends in a contaminant's production, use, and release that may affect its presence in the environment and potential occurrence in drinking water. The cancellation of a pesticide or a clear increase in production and use of a contaminant are trends that can inform the regulatory determination process. A more detailed discussion of the supplemental sources of information/data that
(1) Chemical Update System/Inventory Update Rule (CUS IUR)
The IUR regulation requires manufacturers and importers of certain chemical substances, included on the Toxic Substances Control Act (TSCA) Chemical Substance Inventory, to report site and manufacturing information and the amount of chemicals produced or imported in amounts of 25,000 pounds or more at a single site. Additional information on domestic processing and use must be reported for chemicals produced or imported in amounts of 300,000 pounds or more at a single site. Prior to the 2003 TSCA Amendments (i.e., reporting from 2002 or earlier), information was collected for only organic chemicals that were produced or imported in amounts of 10,000 pounds or more, and was limited to more basic manufacturing information such as production volume. Because of changes in reporting rules, contaminants may have reports for some years but not others (USEPA, 2010a).
(2) Toxic Release Inventory (TRI)
EPA established the Toxics Release Inventory (TRI) in 1987 in response to Section 313 of the Emergency Planning and Community Right-to-Know Act (EPCRA). EPCRA Section 313 requires facilities to report to both
Although TRI can provide a general idea of release trends, it has limitations because of the reporting changes over time. Finally,
(3) Pesticide Usage Estimates
For the regulatory determinations process, the agency reviews various sources of information about pesticide usage. SDWA directs
Occasionally,
The National Center for Food and Agricultural Policy (NCFAP), a private non-profit institution, has also produced national pesticide use estimates based on USDA State-level statistics and surveys for commercial agriculture usage patterns and State-level crop acreage. The database contains estimates of pounds applied and acres treated in each State for 220 active (pesticide) ingredients and 87 crops. The majority of the chemicals monitored are herbicides, but the database also follows significant numbers of fungicides and insecticides (NCFAP, 2000).
The USGS produced usage estimates and maps for over 200 pesticides used in
IV. Contaminant-Specific Discussions for the RD 3 Preliminary Regulatory Determinations
A. Summary of the Preliminary Regulatory Determination
Based on
Table 7--Summary of the Health and Occurrence Information and the Preliminary Determinations for the Five Contaminants Considered for Regulatory Determinations 3 No. RD 3 Health Occurrence findings from primary contaminants reference data sources level (HRL) Primary database PWSs with at least 1 detection >/=1/2 HRL 1 Dimethoate 15.4 [mu]g/L UCMR 2 0% (0 of 4138) 2 1,3- 0.7 [mu]g/L UCMR 2 0% (0 of 4137) Dinitrobenzene 3 Strontium 1,500 [mu]g/L NIRS 14.3% (141 of 989) 4 Terbufos 0.35 [mu]g/L UCMR 1 0% (0 of 295) 5 Terbufos Sulfone 0.35 [mu]g/L UCMR 2 0.02% (1 of 4138)
Table 7--Summary of the Health and Occurrence Information and the Preliminary Determinations for the Five Contaminants Considered for Regulatory Determinations 3 No. Occurrence findings from primary data sources Preliminary determination Population served PWSs with at Population served by PWSs with at least 1 by PWSs with at least 1 detection >/=HRL least 1 detection >/=1/2 detection HRL >/=HRL 1 0% (0 of 229M) 0% (0 of 4138) 0% (0 of 229M) Do not regulate. 2 0% (0 of 229M) 0% (0 of 4137) 0% (0 of 229M) Do not regulate. 3 16.6% (246K of 7.0% (69 of 989) 10.7% (158.5K of Regulate. 1.5M) 1.5M) 4 0% (0 of 41M) 0% (0 of 295) 0% (0 of 41M) Do not regulate. 5 0.01% (44.6K of 0.02% (1 of 4138) 0.01% (44.6K of Do not regulate. 229M) 229M)
B. Contaminant Profiles
This section provides further information on the background, health, and occurrence data that the agency uses to evaluate each of the five candidate contaminants considered for regulatory determinations. For each candidate, the agency evaluates the available human and toxicological data, derives a health reference level, and evaluates the potential and/or likely occurrence and exposed population for the contaminant in public water systems. The agency also considers whether information is available on sensitive populations. The agency uses the findings from these evaluations to determine whether the three SDWA statutory criteria are satisfied. The agency also prepares a regulatory support document (USEPA, 2014b) that provides more details on the background, health, and occurrence information/analyses used to evaluate and make preliminary determinations for these five contaminants.
1. Dimethoate
a. Background
Dimethoate is an organophosphate pesticide, commonly used as an insecticide on field crops (e.g., wheat, alfalfa, corn, and cotton), orchard crops, vegetable crops, and in forestry. Synonyms for dimethoate include dimethogen, dimeton, dimevur, and cygon (HSDB, 2009; USEPA, 2007b).
b. Statutory Criterion #1 (Adverse Health Effects)
Dimethoate meets the SDWA statutory criterion #1 for regulatory determinations; it may have an adverse effect on the health of persons. Dimethoate belongs to a group of pesticides called organophosphates, which share a common MOA. Organophosphates affect the proper function of the nervous system by inhibiting cholinesterase (ChE), an important enzyme involved in neurotransmission. Inhibition of ChE in the brain, plasma, and red blood cells is the most sensitive endpoint described in numerous studies with adult and juvenile animals, following oral, dermal, or inhalation exposures of dimethoate or its primary toxic metabolite omethoate (USEPA, 2007b). As discussed in the 2007 OPP assessment, the
The 2007 OPP assessment established a chronic oral RfD for dimethoate of 0.0022 mg/kg/day based on a 2-year feeding study in rats with inhibition of brain ChE as the critical effect (USEPA, 2007b). The RfD was derived using the BMD method and based on the lower 95% confidence limit (BMDL) of 0.22 mg/kg/day, with application of a composite UF of 100 (i.e., intraspecies and interspecies variability).
c. Statutory Criterion #2 (Occurrence at Frequency and Levels of Public Health Concern)
Dimethoate does not meet the SDWA statutory criterion #2 for regulatory determinations; it does not occur with a frequency and at levels of public health concern in public water systems based on
The primary data for dimethoate are recent (2008-2010) nationally-representative drinking water monitoring data, generated through
The State of California reported results from testing more than 20,000 finished drinking water samples from over 2,000 PWSs and dimethoate was detected in two samples from two different PWSs. The detected concentrations (1 [mu]g/L and 2 [mu]g/L) were less than the 1/2 HRL (7.7 [mu]g/L) and the HRL (15.4 [mu]g/L) (see USEPA, 2014b). The USDA PDP monitored for dimethoate in finished water from 2001 to 2009 and had only two detections in 3,555 samples; both detected concentrations were less than the 1/2 HRL and the HRL (
Dimethoate occurrence data for ambient water are consistent with those for finished drinking water. The USGS PMP also monitored for dimethoate in ambient water in 1999 and had no detections greater than the 1/2 HRL (7.7 [mu]g/L) or the HRL (15.4 [mu]g/L) in any of the 317 samples (Blomquist et al., 2001). Ambient water data from a two-phase USGS study conducted between 2002 and 2005 by Hopple et al. (2009) and Kingsbury et al. (2008) reported no detections in the 221 Phase 1 groundwater samples. Only two detections were reported from 146 Phase 1 surface water samples at nine PWSs. The highest concentration detected was 0.009 [mu]g/L, which is less than the 1/2 HRL and the HRL. In Phase 2, there were no detections of dimethoate from 48 raw and finished water groundwater samples (Hopple et al., 2009; Kingsbury et al., 2008). Ambient water data in STORET included no measured results above 0.44 [mu]g/L in 5,299 samples from 798 sites (USEPA, 2012b). Ambient water data reported by the
d. Statutory Criterion #3 (Meaningful Opportunity)
EPA finds that dimethoate does not meet the SDWA statutory criterion #3 for regulatory determinations; regulation of dimethoate does not present a meaningful opportunity health risk reduction for persons served by PWSs based on the estimated exposed population, including sensitive populations. The estimated population exposed to dimethoate at levels of public health concern is 0%; it was not found to occur at levels above the HRL (or the 1/2 HRL) in 4,138 PWSs and 32,013 samples from the UCMR 2 monitoring. In addition, other supplementary sources of finished water and ambient water data indicate that the occurrence of dimethoate in PWSs is likely to be low to non-existent. As a result, the agency finds that an NPDWR for dimethoate does not present a meaningful opportunity for health risk reduction.
EPA also evaluated whether health information is available regarding the potential health effects on children and other sensitive populations. The database for dimethoate includes a 3-generation reproductive study in mice, developmental (teratology) studies in rats and rabbits, and a neurodevelopmental toxicity study (USEPA, 1990a, 2007b). The critical effect of ChE inhibition is a more sensitive endpoint compared to the reproductive and developmental endpoints (USEPA, 2007b); therefore no sensitive populations were identified or characterized. The OPP RED (USEPA, 2007b) presents more detailed information about the potential health effects and sensitive populations for dimethoate.
e. Preliminary Regulatory Determination
The agency is making a preliminary determination to not regulate dimethoate with an NPDWR after evaluating health, occurrence, and other related information against the three SDWA statutory criteria. While data suggests that dimethoate may have an adverse effect on human health, the occurrence data indicate that dimethoate is not occurring or not likely to occur in PWSs with a frequency and at levels of public health concern. Therefore, the agency finds that an NPDWR would not present a meaningful opportunity to reduce health risk for persons served by PWSs. The Regulatory Determinations 3 Support Document (USEPA, 2014d) and the Occurrence Data from the Second Unregulated Contaminant Monitoring Regulation (UCMR 2) (USEPA, 2014a) present additional information and/or analyses supporting the agency's evaluation of dimethoate.
2. 1,3-Dinitrobenzene
a. Background
1,3-Dinitrobenzene is a nitro aromatic compound that is used as an industrial chemical and formed as a by-product in the manufacture of munitions as well as in the production of other substances (HSDB, 2009). There are no known natural sources of 1,3-dinitrobenzene. Annual production and importation of 1,3-dinitrobenzene in
b. Statutory Criterion #1 (Adverse Health Effects)
1,3-dinitrobenzene meets the SDWA statutory criterion #1 for regulatory determinations; it may cause adverse effect on the health of persons. 1,3-dinitrobenzene has demonstrated adverse health effects in many rodent and occupational studies. Occupational studies indicate that methemoglobinemia, hemolytic anemia, and cyanosis are seen in workers who experience an acute reaction to 1,3-dinitrobenzene (Hajjar et al., 1992). The EPA IRIS assessment (USEPA, 1990b) of the carcinogenicity of 1,3-dinitrobenzene currently lists it as Group D (not classifiable as to human carcinogenicity).
The primary adverse biological effects from exposure to 1,3-dinitrobenzene are on red blood cells, spleen, and testes. The RfD for 1,3-dinitrobenzene is 0.0001 mg/kg/day (Cody et al., 1981). The RfD was derived from a NOAEL of 0.4 mg/kg/day in a subchronic oral study in rats where increased spleen weight was identified as the critical effect (Cody et al., 1981). A composite UF of 3,000 (intraspecies variability, interspecies variability, subchronic to chronic duration, and lack of chronic, developmental, and multigenerational reproductive toxicity studies) was applied to the NOAEL to obtain the RfD.
The current
c. Statutory Criterion #2 (Occurrence at Frequency and Levels of Public Health Concern)
1,3-dinitrobenzene does not meet the SDWA statutory criterion #2 for regulatory determinations; it does not occur with a frequency and at levels of public health concern in public water systems based on
The primary data for 1,3-dinitrobenzene are recent (2008-2010) nationally-representative drinking water monitoring data generated through
Findings from the available ambient water data for 1,3-dinitrobenzene are consistent with the results in finished water. Ambient water data in STORET included no measured results above 0.33 [mu]g/L in 143 samples from 70 sites (USEPA, 2012b). It should be noted that some occurrence above the HRL may have gone undetected since reporting levels are not documented.
d. Statutory Criterion #3 (Meaningful Opportunity)
EPA finds that 1,3-dinitrobenzene does not meet the SDWA statutory criterion for regulatory determinations; regulation of 1,3-dinitrobenzene does not present a meaningful opportunity for health risk reduction for persons served by PWSs based on the estimated exposed population, including sensitive populations. The estimated population exposed to 1,3-dinitrobenzene at or above the MRL is 0%; it was not found to occur in finished drinking water at levels > MRL (0.8 [mu]g/L), which is only slightly higher than the HRL (0.7 [mu]g/L), in 32,017 samples and 4,137 PWSs from the UCMR 2 monitoring. As a result, the agency finds that an NPDWR for 1,3-dinitrobenzene does not present a meaningful opportunity for health risk reduction.
EPA also evaluated whether information is available regarding the potential health effects on children and other sensitive populations. Individuals with a genetic predisposition to methemoglobinemia (estimated prevalence in the general population = 1% or 1 per 100) and/or hemosiderosis, neonates, and those co-exposed to other hemolytic agents, could be more sensitive to exposure to 1,3-dinitrobenzene (ATSDR, 1995; Jaffe and Hultquist, 1989). Males having sperm production complications could also have increased sensitivity to 1,3-dinitrobenzene exposure (Hajjar et al., 1992). There is currently no multigenerational animal study available for 1,3-dinitrobenzene, and no data available from studies of 1,3-dinitrobenzene developmental toxicity (Hajjar et al., 1992). However, the RfD incorporated a UF for this database deficiency. The IRIS assessment (USEPA, 1990b) presents more detailed information about the potential health effects and sensitive populations for 1,3-dinitrobenzene.
e. Preliminary Regulatory Determination for 1,3-dinitrobenzene
The agency is making a preliminary determination to not regulate 1,3-dinitrobenzene with an NPDWR after evaluating health, occurrence, and other related information against the three SDWA statutory criteria. While data suggest that 1,3-dinitrobenzene may have an adverse effect on human health, the occurrence data indicate that 1,3-dinitrobenzene is not occurring or not likely to occur in PWSs with a frequency and at levels of public health concern. Therefore, the agency has determined that an NPDWR for 1,3-dinitrobenzene would not present a meaningful opportunity to reduce health risk for persons served by PWSs. The Regulatory Determinations 3 Support Document (USEPA, 2014b) and the Occurrence Data from the Second Unregulated Contaminant Monitoring Regulation (UCMR 2) (USEPA, 2014d) present additional information and analyses supporting the agency's evaluation of 1,3-dinitrobenzene.
3. Strontium
a. Background
Strontium is a naturally occurring element (atomic number 38) and a member of the alkaline earth metals (ANL, 2007). There are several radioactive strontium isotopes formed by nuclear fission of uranium or plutonium. The best known is 90Sr, a legacy from above ground testing of the atomic bomb (half-life 29 years). Since drinking water contamination by radioactive isotopes, including beta particle emitters, is covered under the existing radionuclides rule, this FR notice deals primarily with the stable 88Sr isotope which represents 83% of total environmental strontium (ATSDR, 2004).
Strontium mineral mining ceased in
Historically, the most important commercial use of strontium has been in the faceplate glass of cathode-ray tube televisions to block x-ray emissions (ATSDR, 2004). Conversely, flat panel televisions incorporating LCD or Plasma displays are not capable of emitting x-radiation; therefore, they do not require strontium (
b. Statutory Criterion #1 (Adverse Health Effects)
Strontium meets the SDWA statutory criterion #1 for regulatory determinations; it may have an adverse effect on the health of persons. The primary target of strontium exposure is the bone. The chemical similarity of strontium to calcium allows it to exchange imperfectly for calcium in a variety of biological processes; the most important of these is the substitution of calcium in bone, affecting skeletal development. Due to the MOA for strontium toxicity, strontium uptake into bone is affected by the intake of nutrients related to bone formation, such as calcium, phosphorous, and vitamin D (
A study based on decreased bone calcification rate in male weanling rats (i.e., comparable to the sensitive time period in humans), which administered strontium chloride in drinking water for nine weeks (Marie et al., 1985), was identified by
EPA released an IRIS assessment for strontium in 1992 and developed an RfD of 0.6 mg/kg/day based on the Storey, 1961 study. The IRIS assessment was completed before the 1998 changes to the IRIS program wherein the agency develops and peer reviews a detailed Toxicological Review before posting an IRIS summary. The point of departure for the 1992 IRIS RfD of 0.6 mg/kg/day is a NOAEL of 190 mg Sr/kg-day with a composite UF of 300 (10 for interspecies variability, 3 for intraspecies variability, and 10 for database uncertainties). This would yield an HRL of 3000 [mu]g/L, using the same age-specific exposure adjustment factors described above. If the age-specific exposure adjustment factors were not used, the HRL would be 2000 [mu]g/L based on the OW assessment, or 4000 [mu]g/L based on the IRIS assessment. As noted in section III.C.1.c,
There is inadequate information to assess the carcinogenic potential of strontium due to the lack of adequate studies of chronic duration. The Health Effects Support Document (USEPA, 2014c) for this determination presents more detailed analysis of the health effects of strontium.
c. Statutory Criterion #2 (Occurrence at Frequency and Levels of Public Health Concern?)
Strontium meets the SDWA statutory criterion #2 for regulatory determinations; it does occur with a frequency and at levels of public health concern in public water systems based on
EPA used the
Table 8--Estimates of Population Exposed to Strontium, Observed and Extrapolated From NIRS National Inorganics and Extrapolation of NIRS data to Radionuclides Survey (NIRS) groundwater systems nationwide Threshold Systems Population Systems Population Systems with 99.1% 99.9% 99.1% 99.9% Detectable (980 of 989) (1.481M of (39.7K of (93.0M of Concentrations 1.482M) 40.1K) 93.1M) Systems 14.3% 16.6% 14.3% 16.6% detecting (141 of 989) (246K of 1.5M) (5.7K of (15.4M of strontium 40.1K) 93.1M) above one half the HRL (>750 [micro] g/L) Systems 7.0% 10.7% 7.0% 10.7% detecting (69 of 989) (159K of 1.5M) (2.8K of (10.0M of strontium 40.1K) 93.1M) above the HRL (>1500 [micro] g/L)
As a point of reference to the earlier IRIS assessment, if
Finished water data, analyzed between 1998 and 2005, from
Although there are limited surface water data available for strontium, the available data are consistent and demonstrate high occurrence in surface waters. Ambient water data for strontium are also consistent with high occurrence in finished water, which is expected since it is a naturally occurring element. The NAWQA Quality of Public Supply Wells (Toccalino et al., 2010) study collected water samples from source (untreated) groundwater public supply wells in 41 states. Each well was sampled once from 1993-2007 and 100% of samples (503 of 503) had a strontium detection. Of the detections, 25.1% (126 of 503) were above the 1/2 HRL (750 [mu]g/L) and 12.1% (61 of 503) were above the HRL (1500 [mu]g/L). Additional occurrence information on strontium can be found in the Regulatory Determinations 3 Support Document (USEPA, 2014b).
d. Statutory Criterion #3 (Meaningful Opportunity?)
EPA makes a preliminary finding that strontium meets the SDWA statutory criterion #3 for regulatory determinations; regulation of strontium in drinking water presents a meaningful opportunity for health risk reduction based on the estimated exposed population, potential impacts on sensitive populations and estimated exposure from other sources (e.g., food).
1. National Population Exposed: In the NIRS dataset 989 ground water systems were sampled serving a population of 1.48 million. The NIRS data indicates that the population exposed to strontium at a level greater than the HRL (1500 [mu]g/L) is 158,557 (11%) and the 1/2 HRL (750 [mu]g/L) is 245,870 (17%) (USEPA, 2012b).
Strontium occurs naturally and is abundant in the environment. Its occurrence in water at concentrations >HRL may be a reflection of the geologic and geochemical setting of the source waters for PWSs. The NIRS drinking water data showed that strontium was detected in one or more systems sampled in all 48 continuous states,
2. Exposure from media other than water:
An FDA Total Diet Study by Pennington and Jones (1987) collected 234 individual foods in 1984 from three cities in one region of the country and indicated dietary intakes of 493 [mu]g/day for young children (6 to 11 months), 928 to 1,388 [mu]g/day for 14 to 16 year old adolescents, and 979-1,489 [mu]g/day for adults. The FDA Total Diet Study foods are prepared with distilled water and do not reflect any contributions from the cooking water during preparation of foods that absorb water such as rice and pasta. Thus, the strontium in many foods will be impacted by the strontium levels in the local water supply. Using the mean of the detected water concentrations from the NIRS dataset (603 [mu]g/L), the estimated water intake for young children (90th percentile water intake of 1L/day) is 603 [mu]g/day and 1,206 [mu]g/day for adults (90th percentile water intake of 2L/day). The estimated strontium intakes from air and soil are very low compared with those from food and drinking water. The estimated air exposure for children is 0.1 [mu]g/day and for adults is 0.3 [mu]g/day (Dzubay and Stevens, 1975). The estimated exposure from soil is 24 [mu]g/day for children and 12 [mu]g/day for adults (Shacklette and Boerngen, 1984). No data were identified on consumer products, such as toothpaste that contain strontium as an ingredient or impurity.
3. Sensitive populations: Children are expected to be a sensitive population, since they are actively growing and strontium can substitute for calcium in growing bone. This means that changes in bone structure and homeostasis may have more severe and/or a long-term impact than similar changes in adults. These effects would be expected to have the greatest impact during periods of rapid growth in the developing fetus, during childhood and adolescence, particularly if their calcium intake is insufficient (Abrams et al., 2000; Lee et al., 1996; Matkovic et al., 2005; Storey, 1961). The estimated populations of pregnant women (and thus fetuses) and of children (< 17 years old) are 6 and 75 million, respectively (O'Day et al., 1998). The RfD was based on changes in bone growth in weanling rats (i.e., the sensitive population). As a result, the data do not include the risk during prenatal development and lactation so these factors were considered when selecting the UFs used to derive the RfD. Age-specific exposure factors (USEPA, 2012c) were also used to reflect the sensitive population (birth through 18 years) in derivation of the HRL. Exposures from drinking water at or below the HRL (1500 [mu]g/L) are expected to be protective of the sensitive population, assuming that 80% of exposure comes from other sources such as air, soil and food.
The toxic effects of strontium result from strontium ions substituting for calcium ions, therefore calcium deficiency would be expected to result in increased risk among sensitive populations. In this respect, it is important to note that recent NHANES data indicate that about 50% of females, nine years and older, fail to receive adequate calcium from diet and supplements on a daily basis (IOM, 2010). Groups with higher risks of becoming calcium deficient include: Adolescent girls, postmenopausal women, amenorrheic women, female athletes, vegans, and individuals with lactose intolerance or cow's milk allergies (IOM, 2010; NIH, 2011a).
The major route of elimination of strontium is via the kidneys, therefore individuals with impaired renal function are another sensitive population. This population may potentially have impaired strontium clearance, as has been shown in renal failure patients. There are approximately 20 million people (10%) above the age of 20 with chronic kidney disease (CDC, 2010) and 548,000 people with kidney end-stage renal disease (USRDS, 2010), who may be at an increased risk. People with disorders affecting the normal equilibrium between the breakdown of old bone and the formation of new bone (such as Paget's disease) might also be sensitive to strontium exposure (D'Haese et al., 1999, 2000; Schrooten et al., 1998, 2003; Tothill et al., 1983). According to the
d. Preliminary Regulatory Determination
At this time, the agency is making a preliminary determination to regulate strontium with an NPDWR after evaluating the available health, occurrence, and other related information against the three SDWA statutory criteria. Specifically, it is
It is important to note that the agency included strontium in UCMR 3. As of
4 and 5. Terbufos and Terbufos Sulfone
a. Background
Terbufos is a phosphorodithioate pesticide (i.e., an organophosphate) used as an insecticide-nematicide to control a variety of insect pests, primarily used on corn and sugar beets (USEPA, 2006c). Terbufos sulfone is a degradate of terbufos.
b. Statutory Criterion #1 (Adverse Health Effects?)
Terbufos and its degradate, terbufos sulfone, meet the SDWA statutory criterion #1 for regulatory determinations; they may cause an adverse effect on the health of persons. Terbufos and terbufos sulfone belong to a group of pesticides called organophosphates, which share a common mechanism of toxicity. Organophosphates affect the proper function of the nervous system by inhibiting ChE, an essential enzyme in neurotransmission. There has been no evidence that terbufos is carcinogenic in animal studies (
The 2006 OPP RED assessment (USEPA, 2006c) established an oral RfD for terbufos of 0.00005 mg/kg/day, derived from the NOAEL of 0.005 mg/kg/day for ChE inhibition in the 28-day and 1-year dog studies by Shellenberger (1984) and Shellenberger and Billups (1986). A composite UF of 100 (interspecies and intraspecies variability) was applied to the NOAEL to obtain the RfD.
c. Statutory Criterion #2 (Occurrence at frequency and levels of public health concern?)
Terbufos and terbufos sulfone do not meet the SDWA statutory criterion #2 for regulatory determinations; they do not occur with a frequency and at levels of public health concern in public water systems based on
The primary data for terbufos sulfone are nationally-representative finished water monitoring data generated through
Terbufos and (very limited) terbufos sulfone occurrence data for ambient water from
Ambient water data from a two phase USGS study conducted between 2002 and 2005 by Hopple et al. (2009) and Kingsbury et al. (2008) reported no terbufos detections in the 221 Phase 1 groundwater samples nor the 146 Phase 1 surface water samples. In Phase 2, there were no detections of terbufos from 48 raw and 48 finished groundwater samples. Ambient water data from a USGS study conducted between 1993 and 2007 by Toccalino et al. (2010) reported no terbufos detections in 898 groundwater samples.
Terbufos ambient data reported in
Terbufos ambient data are reported in STORET from 17 States (USEPA, 2012b). No groundwater detections were reported in 699 samples at 441 sites. STORET reported surface water detections in 457 of 5,826 samples (7.84%) at 138 of 625 sites (22.1%). Of the 457 surface water detections, only 23 samples (0.39%) at 14 sites (2.24%) were above the 1/2 HRL and only two samples (0.03%) at two sites (0.32%) were above the HRL.
d. Statutory Criterion #3 (Meaningful Opportunity?)
Terbufos and terbufos sulfone do not meet the SDWA statutory criterion #3 for regulatory determinations; regulation of terbufos and terbufos sulfone do not present a meaningful opportunity for health risk reduction based on the estimated population exposed, including sensitive populations. The estimated population exposed to terbufos at or above the MRL is 0%; the compound was not found to occur in finished water at levels greater than or equal to the MRL (0.4 [mu]g/L), which is slightly higher than the HRL (0.35 [mu]g/L), in 2,301 samples from 295 PWSs in UCMR 1 (USEPA, 2008c). The estimated population exposed to terbufos sulfone at a level of public health concern (based on the HRL for terbufos) is 44,600 (0.02% of the population served by PWSs); there was only one detection greater than the HRL in 4,138 PWSs (1 of 32,012 samples in UCMR 2) (USEPA, 2014d). As a result, the agency finds that an NPDWR does not present a meaningful opportunity for health risk reduction.
EPA also evaluated whether health information is available regarding the potential health effects on children and other sensitive populations. Developmental studies with terbufos in rats and rabbits did not find any developmental effects (USEPA, 2003c). There are no data on reproductive and developmental effects for terbufos sulfone. No sensitive populations were identified or characterized. The OPP RED (USEPA, 2006c) presents more detailed information about the potential health effects and sensitive populations for terbufos and terbufos sulfone.
e. Preliminary Regulatory Determination
The agency is making preliminary determinations to not regulate terbufos and terbufos sulfone with NPDWRs after evaluating health, occurrence, and other related information against the three SDWA statutory criteria. While the data suggests that terbufos and terbufos sulfone may have adverse effects on human health, the occurrence data indicate there is no substantial likelihood that terbufos or terbufos sulfone will occur in PWSs with a frequency and at levels of public health concern. Therefore, the agency finds that NPDWRs for terbufos and terbufos sulfone would not present meaningful opportunities to reduce health risk for persons served by PWSs. The Regulatory Determinations 3 Support Document (USEPA, 2014b) presents additional information and/or analyses supporting the agency's evaluation of terbufos and terbufos sulfone.
V. What is the Status of the Agency's Evaluation of Chlorate and Nitrosamines?
The agency will review the existing MDBP regulations as part of the SY3. Because chlorate and nitrosamines are DBPs that can be introduced or formed in public water systems partly because of disinfection practices, the agency believes it is important to evaluate these unregulated DBPs in the context of the review of the existing DBP regulations. DBPs need to be evaluated collectively, because the potential exists that the chemical disinfection used to control a specific DBP could affect the concentrations of other DBPs. Therefore, the agency is not making a regulatory determination for chlorate and nitrosamines at this time. The agency expects to complete the review of these DBPs by the end of 2015.
A. Chlorate
The following sections provide the background, health and occurrence information/data that the agency has collected to date for chlorate. If the public has any additional health and occurrence information that may be useful as the agency evaluates chlorate in the context of the existing MDBP rules, please provide this information to the docket.
1. Background
The chlorate anion (ClO3-) forms a variety of salts (e.g., sodium chlorate, calcium chlorate, potassium chlorate, and magnesium chlorate) collectively known as chlorates, which are powerful oxidizers. Chlorate compounds (especially sodium chlorate) are used as herbicides and to generate chlorine dioxide (ClO2) as a bleaching agent (USEPA, 2006a). Disinfection practices are the most important source of chlorate in drinking water; this includes formation as a DBP from use of chlorine dioxide and its presence in hypochlorite disinfectants as an impurity (USEPA, 2006a).
Chlorate can be formed during decomposition of hypochlorite (ClO-) solutions, which are used as a disinfectant and/or oxidant in water treatment. Hypochlorite solutions that are more aged are generally less effective and require higher doses to achieve the treatment (disinfection) objectives, which can result in more chlorate to be introduced into the chlorinated water. In addition to being a DBP (along with chlorite) formed from the use of chlorine dioxide as a disinfectant, chlorate ion may also be present as an impurity in the chlorine dioxide (Gates et al., 2009; USEPA, 2006a). Chlorate can also form by the reaction of chlorite with free chlorine applied as a residual disinfectant in the distribution system (Gallagher et al., 1994). In addition, chlorite can be oxidized by a strong oxidant (such as ozone) to produce chlorate in the water (
2. Health Effects Information
Acute ingestion of high levels of sodium chlorate has resulted in acute kidney failure and hemolysis among other effects based on numerous case reports of individuals accidently ingesting high levels of chlorate compounds (USEPA, 2006b; WHO, 2005). A population-based case-control study of chlorate as a DBP at concentrations >200 [mu]g/L identified significantly increased odds ratios for obstructive urinary defects, cleft palate, and spina bifida (Righi et al., 2012). The median chlorate exposure for the study population was 280 [mu]g/L. In a case-control study of the same population in
The animal studies provide clear and consistent evidence that subchronic and chronic exposure to chlorate results in effects on blood and thyroid. Subchronic studies in rats have reported decreased hemoglobin, hematocrit, and red blood cell (RBC) counts (Abdel-Rahman et al., 1984; Barrett, 1987; McCauley et al., 1995) and thyroid colloid depletion, follicular cell hypertrophy and hyperplasia (Hooth et al., 2001).
A chronic study based on increased thyroid gland follicular cell hypertrophy in male rats (NTP, 2005a) was identified as the critical study for establishing an RfD of 0.03 mg/kg/day (USEPA, 2006b). The RfD was derived by using the BMD method and based on the lower 95% confidence limit (BMDL) of 28 mg/L as sodium chlorate (22 mg/L as chlorate), corresponding to 0.9 mg/kg/day (USEPA, 2006b), with a composite UF of 30 for intraspecies (i.e., sensitive populations) and interspecies variability (i.e., thyroid hormone differences between humans and rats).
A cancer risk assessment was not conducted for chlorate because sodium chlorate is classified as not likely to be carcinogenic to humans at doses that do not alter thyroid hormone homeostasis under the USEPA (2005b) Cancer Guidelines. The RfD is protective against acute alterations in thyroid homeostasis and therefore considered to also be protective of tumorigenicity as well as other chronic and subchronic adverse health effects discussed in the literature (Hooth et al., 2001; Khan et al., 2005; NTP, 2005a).
EPA also evaluated whether health information is available regarding sensitive populations. According to the OPP RED, there was no pre- or postnatal sensitivity or susceptibility observed in the submitted developmental studies in rats and rabbits or the 2-generation reproduction study in rats. However, there is a concern for developing offspring because of the effects of inorganic chlorate on thyroid function in rats (USEPA, 2006a). Chlorate is one of a number or inorganic ions that may interfere with iodine uptake by the thyroid, but chlorate is not highly potent in this respect (Van Sande et al., 2003).
Chlorate may also cause hemolysis, thus persons with low red blood cell counts such as those with anemia may be particularly sensitive to sodium chlorate. Data from the 1994
3. Occurrence Data and Information
a. Drinking Water
The 1997-1998 DBP ICR is currently the best available data source for characterizing the national occurrence baseline for chlorate. The DBP ICR, which included monitoring data for 296 water systems serving 100,000 people or more (representing a total population of 130 million), required water systems that use hypochlorite solutions or chlorine dioxide for disinfection to monitor for chlorate (USEPA, 1996). Subsequently, 82 water systems serving approximately 40 million people monitored and reported chlorate occurrence under the DBP ICR (using an MRL of 20 [mu]g/L). Table 9 presents the number and percentage of samples and systems (along with the population served) that measured chlorate at levels exceeding the specified threshold concentrations (i.e., HRL and 1/2 HRL). These samples were associated with 41.5% (34 of 82) of the ICR systems using hypochlorite solutions or chlorine dioxide for disinfection and 11.5% (34 of 296) of all of the ICR systems.
Since the DBP ICR was completed in 1998, these data likely underestimate current (2012) chlorate occurrence among the systems serving 100,000 people or more for the following two reasons: (1) Some of these systems may have changed the disinfectant type from chlorine gas to chlorine dioxide for compliance with the existing Stage 1 or Stage 2 DBP rules; and/or (2) some systems may have switched from chlorine gas to hypochlorite solution due to a security concern (i.e., a concern of safety of transportation and storage for chlorine gas). Disinfection surveys conducted by the AWWA Disinfection Systems Committee in 1998 and 2007 have confirmed that chlorine dioxide and hypochlorite use has increased (AWWA Disinfection Systems Committee, 2008a, 2008b; Connell et al., 2000a, 2000b). GOES
Table 9--Summary of Chlorate Monitoring Results Under the DBP ICR Of DBP ICR PWSs that Of all DBP ICR PWSs, PWSs monitored for chlorate, with at least one detection > samples and PWSs with at threshold and estimated least one detection > population served ** threshold * Chlorate Number Number Number Population threshold (percentage) (percentage) (percentage) served by DBP of DBP ICR of DBP ICR of DBP ICR ICR PWSs with samples with PWSs with at PWSs with at at least one detection > least one least one detection > threshold detection > detection > threshold ** threshold threshold * HRL (210 332 of 1,719 34 of 82 34 of 296 11.8 of 130 [mu]g/L) (19.3%) (41.5%) (11.5%) million (9.1%) 1/2 HRL (105 878 of 1,719 60 of 82 60 of 296 31.7 of 130 [mu]g/L) (51.1%) (73.2%) (20.3%) million (24.4%) * 82 PWSs that used hypochlorite or chlorine dioxide were required to monitor for chlorate during the DBP ICR monitoring period, based on their potential to form chlorate. Number and percentage of samples and PWSs are based on those 82 PWSs that monitored for chlorate. ** The number and percentage of PWSs and population served > threshold is based on all 296 systems.EPA assumes that the 214 systems not required to monitor do not have chlorate concentrations above the thresholds.
Finished water data for chlorate from
It is important to note that the agency included chlorate in the UCMR 3, which is currently in process. UCMR 3 will provide a national dataset of chlorate occurrence in drinking water and will update the occurrence data provided by the DBP ICR.
Ambient water data for chlorate are limited, but chlorate could be present in areas where it is used as an herbicide or discharged from paper plants where it is used as a bleaching agent. Since chlorate is a DBP, higher concentrations are expected in finished water than in ambient water.
b. Exposure from media other than water
There is very little quantitative information available on the occurrence of chlorate in food, air, and soil or other products resulting in residential exposures. Without reliable estimates of intakes, it is not possible to estimate the contribution of drinking water to total exposure. However, based on modeling results, the agency estimated that the chlorate intake from food (as a result of sodium chlorate use as a pesticide) for the overall population is approximately 3 [mu]g/kg-day, with somewhat higher intakes for children under five years old of approximately 5 to 8 [mu]g/kg-day (USEPA, 2006a). Additional food exposure from use of sanitizing solutions in food preparation plants (e.g., equipment and contact surfaces) and processing (e.g., bleaching agent) may also be a source of exposure (21 CFR section 178.1010). Intake for adults from dietary supplements containing chlorate may range from 0.001 to 0.29 [mu]g/kg-day.
B.
The following sections provide the background, health and occurrence information/data that the agency has collected to date for nitrosamines. If you have any additional health and occurrence information that may be useful as the agency evaluates nitrosamines in the context of the regulatory review of existing MDBP rules, please provide this information to the docket.
1. Background
Nitrosamines are a class of nitrogen-containing organic compounds that share a common nitrosamino functional group (HSDB, 2010).
All six nitrosamines may be produced in small quantities for research purposes, but only one (NDEA) is currently produced commercially in
NDMA can be formed as an unintended byproduct of manufacturing processes that involve the use of nitrite or nitrate and amines, including tanneries, fish processing plants, foundries, and pesticide, dye, rubber or tire manufacturing plants (ATSDR, 1989). Nitrosamines have been found in tobacco products, cured meats, ham, bacon, beer, whiskey, fish, cheese, soybean oil, toiletries, household cleaners, pesticides, rubber baby bottle nipples and pacifiers (ATSDR, 1989; Drabik-Markiewicz et al., 2009; Fine et al., 1977; NTP, 2011; Perez et al., 2008; Yurchenko and Moelder, 2007).
NDMA is commonly present in municipal sewage sludge (ATSDR, 1989). NPYR has also been detected in municipal sewage sludge (HSDB, 2010). ATSDR (1989) cites several studies indicating that nitrosamine formation in sewage sludge appears to be the result of biological and chemical transformation of alkylamines in the presence of nitrite. In addition, nitrosamines may form in air, soil, water, sewage, food, animal systems and other media where precursors (e.g., amines and nitrite) are present (HSDB, 2010). NDMA can be produced endogenously in humans from the interaction of nitrates and nitrites with amines in the stomach (Mirvish 1975, 1992; Tricker et al., 1994).
As described in the following occurrence section, nitrosamines in finished water are commonly considered as DBPs because most of the literature indicates that the main source of nitrosamines in finished water is associated with water treatment, particularly from disinfection with chloramines. NDMA is the predominant species of nitrosamines found in finished water; other nitrosamines are detected less frequently. Based on their physical and chemical properties, the nitrosamines appear to be moderately to very mobile in the environment (the exception being NDBA, which is of low mobility). The nitrosamines are subject to a variety of removal mechanisms when present in soil and water, including volatilization (particularly NDMA), photodegradation, and microbial degradation, although the rates and extent of biodegradation are highly variable (HSDB, 2010).
2. Health Effects Information
As the more thoroughly studied nitrosamine compared to the other nitrosamine compounds, NDMA provides epidemiological case-control and other evidence that human nitrosamine exposure is associated with an increased risk of several types of cancer, including cancer of the stomach, esophagus, oral cavity, and pharynx (La Vecchia et al., 1995; Larsson et al., 2006; Loh et al., 2011; Straif et al., 2000). In accordance with the most recent Guidelines for Carcinogen Risk Assessment (USEPA, 2005b),
With a mutagenic MOA, Age Dependent Adjustment Factors (ADAFs) are used to account for the potential increased cancer risk due to early-life exposure for infants and children (USEPA, 2005c). The age-adjusted unit risk is determined by summing up each of the time-weighted unit risks for the three ADAF developmental groups. The age-adjusted unit risks include a ten-fold adjustment for birth to < 2 years, a three-fold adjustment for 2 years to < 16 years, and no additional adjustment for exposures later in life, in conjunction with age-specific drinking water intake values (USEPA. 2012c), and the fraction of a 70-year lifetime applicable to each age period. The main cancer risk values used to derive the HRLs are further explained in section III.C.1 and are also summarized for nitrosamines in Table 10 below.
Table 10--EPA Derived Risk Values and HRLs for the Six Individual Nitrosamines Nitrosamines Studies for Cancer *1 Age- *2 HRL *3 HRL establishing a slope adjusted ([mu]g/L) (ng/L) slope factor factor unit risk (mg/kg/day) ([mu]g/L) 1 1 NDBA Liver and 0.4 3.0 x 105 3 x 102 30 esophageal tumors in rats (Druckrey et al., 1967) NDEA Liver and 30 2.3 x 103 4 x 104 0.4 esophageal tumors in rats (Peto et al., 1991a,b) NDMA Liver tumors in 21 1.6 x 103 6 x 104 0.6 rats (Peto et al., 1991a,b) NDPA Liver and 2 1.5 x 104 7 x 103 7 esophageal tumors in rats (Druckrey et al., 1967) NMEA Liver tumors in 4 3.0 x 104 3 x 103 3 rats (Druckrey et al., 1967) NPYR Liver tumors in 7 5.3 x 104 2 x 103 2 rats (Peto et al., 1984) *1 Based on the recommendations of theU.S EPA's 2005 Supplemental Guidance for Assessing Susceptibility from Early-Life Exposure to Carcinogens, the Unit Risk applicable to exposures beginning in early-life was adjusted with ADAFs and age-specific drinking water intakes resulting in a lifetime value of unit risk for exposure to 1 [mu]g/L of a contaminant. The calculation for Age-Adjusted Unit Risk = SIGMA(CSF x ADAF x DWI/BWR x CW x F). The risk calculations for each individual nitrosamine can be found in the HESDs. *2 The cancer HRL is determined by dividing the population risk level, one-in a million (106), by the age-adjusted unit risk. *3 The nitrosamine HRL values are converted to ng/L units by multiplying the [mu]g/L values by 1000.
As shown in table 10, the available data indicate a range of cancer risk values for the individual nitrosamines. Moreover, when multiple nitrosamines from this group are present in finished water together, their individual cancer risks are additive (Berger et al., 1987).
EPA also evaluated whether health information is available regarding sensitive populations. The fetus, newborns, and infants may be potentially sensitive to the carcinogenic effects of nitrosamines due to the mutagenic MOA and evidence of transplacental carcinogenicity (Althoff et al., 1977; Donovan and Smith, 2008). Studies have found that younger rats were more susceptible to the development of liver tumors compared to rats exposed later in life to nitrosamines (Gray et al., 1991; Peto et al., 1984; Vesselinovitch et al., 1984).
In addition, habitual consumers of alcoholic beverages may be more susceptible to carcinogenic effects of nitrosamines because alcohol increases the metabolism of nitrosamines via a metabolic pathway that leads to the formation of mutagenic DNA adducts. Co-exposure to ethanol has been shown to exacerbate the cancer effects of nitrosamines in animal studies (Anderson et al., 1993; Kamataki et al., 2002;
3. Occurrence Data and Information
The data collected under UCMR 2 (USEPA, 2014d) are currently the best available data for characterizing the national occurrence baselines for the six nitrosamines. Under UCMR 2, PWSs were required to collect a sample at each entry point to the distribution system as well as at the maximum residence time locations within the distribution system associated with each entry point, and to report the disinfectant type in use at these locations at the time that the samples were being taken. The agency was unable to measure at the HRL for some of the nitrosamines. Therefore, Table 11 presents all of the monitoring results for each of the six nitrosamines relative to the MRLs. GOES
Table 11--Summary of UCMR 2 Monitoring Results for Six Nitrosamines Nitrosamines considered under MRL Percentages Percentages Percentages RD 3 (number) of (number) of (number) of samples UCMR 2 PWSs actual UCMR with with at 2 detection least one population detection served with at least one detection* Nitrosamine Group 2 to 7 10.6% 28.6% 46.43% ng/L (1,907 of (343 of (73 of 157 18,053) 1,198) million) NDBA 4 ng/L 0.05% 0.4% 1.07% (9 of (5 of (1.7 of 157 18,043) 1,198) million) NDEA 5 ng/L 0.3% 2.2% 7.14% (46 of (26 of (11.2 of 18,038) 1,198) 157 million) NDMA 2 ng/L 10.2% 27.0% 41.54% (1,841 of (324 of (65.3 of 18,040) 1,198) 157 million) NDPA 7 ng/L 0% 0% 0% (0 of (0 of (0 of 157 18,049) 1,198) million) NMEA 3 ng/L 0.02% 0.3 0.003% (3 of (3 of (0.004 of 18,043) 1,198) 157 million) NPYR 2 ng/L 0.2% 1.8% 4.73% (41 of (21 of (7.4 of 157 18,043) 1,198) million) * The population-served values have been adjusted to include both the population served directly by a system and also the estimated attributable proportion of the population served by other systems that purchase water from the system. These adjustments are described in the UCMR 2 support document.
Finished water data for the nitrosamines from
V. What about the remaining CCL 3 contaminants?
For the remaining CCL 3 contaminants, the agency lacked adequate health and/or occurrence information needed to address the three SDWA statutory criteria to make a regulatory determination. Table 2 and Table 4 of this notice provide information about the data or information gap(s) that prevented the contaminant from moving forward for this regulatory determination effort. The agency continues to conduct research, collect information or find other avenues to fill the data and information gaps identified in Table 2 and 4. One mechanism the agency plans to continue to use to fill occurrence gaps for several of these contaminants is the UCMR.
VI.
EPA intends to carefully evaluate and respond to the public comments received on the five preliminary determinations and issue its final regulatory determinations in 2015. If the agency makes a final determination to regulate any of the contaminants,
VII. References
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Dated:
Administrator.
Appendix: HRL Derivation With Age-Related Exposure Factors GOES
Derivation of the Health Reference Level (HRL) for Strontium Using Age-Specific Exposure Factors Age range DWI/BWR Age-specific Time-weighted (L/kg/day) fractions of a DWI/BWR 19-year exposure (L/kg/day) duration Birth to <1 month 0.235 0.004 0.001 1 to <3 months 0.228 0.009 0.002 3 to <6 months 0.148 0.013 0.002 6 to <12 months 0.112 0.026 0.003 1 to <2 years 0.056 0.053 0.003 2 to <3 years 0.052 0.053 0.003 3 to <6 years 0.043 0.158 0.007 6 to <11 years 0.035 0.263 0.009 11 to <16 years 0.026 0.263 0.007 16 to <18 years 0.023 0.105 0.002 18 to <21 years # 0.026 0.053 0.001 Summation of the Time-Weighted DWI/BWRs = 0.040 L/kg/day * Reference Dose = 0.3 mg/kg/day RSC = 20% *+ HRL = (0.3 mg/kg/day / 0.040 L/kg/day) x .20 = 1.500 mg/L Final child specific HRL: 1500 [mu]g/L * Rounded; # includes 18th year; DWI/BWR = drinking water intake to body weight ratio; HRL= health reference level; RSC = relative source contribution. *+ HRL = (RfD/∑(DWI/BWR x F)) x RSC.
The age-specific data on drinking water intakes in units of L/kg/day from birth through age 3 are from Table 3-19 in the EPA Exposures Factors Handbook (USEPA, 2011e) and from Table 3-38 for ages 3 to < 19 . The exposure duration adjustment was calculated by dividing the age-specific fraction of a 19 year exposure by the total exposure in months or years as appropriate (e.g., birth to < 1 month = (1/12)/19 years = 0.00439; 6 to < 11 years = 5/19 years = 0.26316). The time-weighted DWI/BWR values are the product of the age-specific DWI/BWR multiplied by the age-specific fraction of a 19 year exposure. The time-weighted DWI/BWRs are summed to obtain the normalized value.
[FR Doc. 2014-24582 Filed 10-17-14;
BILLING CODE 6560-50-P
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