Six-Year Review 3
SEPA
SUMMARY HEALTH EFFECTS ASSESSMENT REPORT
United States
Environmental Protection
Agency
December 2016
Six-Year Review 3 - Health
Effects Assessment for Existing
Chemical and Radionuclide
National Primary Drinking
Water Regulations - Summary
	Report	
This document is intended to support U.S. EPA's third Six-Year Review of existing national primary drinking water regulations.
The data presented in this document reflect literature searches through December 2014 and health risk assessments completed by
December 2015.
Office of Water (4304T) EPA 822-R-16-008 December 2016 www.epa.gov/waterscience

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Six-Year Review 3
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Acknowledgements
This document was prepared in part under U.S. EPA Contract EP-C-10-030, Work Assignments
3-08 and 4-08, and U.S. EPA Contract EP-C-12-023, Work Assignment 3-26.
The U.S. EPA Work Assignment Managers for this project were Octavia Conerly and Santhini
Ramasamy of the Office of Science and Technology in the Office of Water.
Technical input to this document was also provided by the following U.S. EPA staff:
Office of Science and Technology. Office of Water:
Octavia Conerly, M.S.P.H.
Nancy Chiu, Ph.D.
Joyce Donohue, Ph.D. R.D.
Steven Kueberuwa, M.S.
Santhini Ramasamy, Ph.D., DABT, MPH
Melanie Young, M.S., M.P.H.
Office of Radiation and Indoor Air:
Neal Nelson, D.V.M., Ph.D.
Jerome Puskin, Ph.D.
Lowell Ralston, Ph.D.
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LIST OF ABBREVIATIONS/ACRONYMS
ADAF- Age- Dependent Adjustment Factor
ADWR - Aircraft Drinking Water Rule
ATSDR- Agency for Toxic Substances and Disease Registry
BMD10- Benchmark Dose at a 10% response
BMDL- Lower confidence limit on the benchmark dose (mg/kg/day)
BW- Body Weight
CalEPA- California Environmental Protection Agency
CCRIS- Chemical Carcinogenesis Research Information System
CICADS- Concise International Chemical Assessment Documents
CSF- Cancer Slope Factor
DART- Developmental and Reproductive Toxicology
DEHP- Di(2-ethylhexyl) phthalate
DWEL- Drinking Water Equivalent Level
DWI- Drinking Water Intake
ED 10- Effective Dose corresponding to a 10% increase in an adverse effect
FAO- Food and Agriculture Organization of the United Nations
FQPA- Food Quality Protection Act
HSDB- Hazardous Substances Data Bank
IARC- International Agency for Research on Cancer
I-Intake from drinking water
IPCS/EHC- International Programme on Chemical Safety/Environmental Health Criteria
IRIS- Integrated Risk Information System
JECFA- Joint Expert Committee on Food Additives
JMPR- Joint FAO/WHO Meeting on Pesticide Residues
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LED 10- 95% Lower Confidence Limit on the Effective Dose
LOAEL- Lowest Observed Adverse Effect Level (mg/kg/day)
LT1 - Long-Term 1 Enhanced Surface Water Treatment Rule
LT2 - Long-Term 2 Enhanced Surface Water Treatment Rule
MCL- Maximum Contaminant Level
MCLG- Maximum Contaminant Level Goal
MF- Modifying Factor
MO A- Mode of Action
MOE- Margin of Exposure
MRLs- Minimal Risk Levels
NAS- National Academy of Sciences
NCWSs- Non-Community Water Systems
NDWAC- National Drinking Water Advisory Council
NHANES- National Health and Nutrition Examination Survey
NIEHS- National Institute of Environmental Health Sciences
NOAEL- No Observed Adverse Effect Level (mg/kg/day)
NPDWR- National Primary Drinking Water Regulation
NTP- National Toxicology Program
OPP- Office of Pesticide Programs
OPP- U.S. EPA Office of Pesticide Programs
ORIA- U.S. EPA Office of Radiation and Indoor Air
OW- U.S. EPA Office of Water
PHG- Public Health Goal
POD- Point of Departure
PQL- Practical Quantitation Level
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RED- Reregi strati on Eligibility Decisions
RfD- Reference Dose
RSC- Relative Source Contribution
SD- Standard Deviation
SDWA- Safe Drinking Water Act
U.S. EPA- United States Environmental Protection Agency
UF- Uncertainty factor
VOCs- Volatile Organic Compounds
WHO- World Health Organization
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Six-Year Review 3 SUMMARY HEALTH EFFECTS ASSESSMENT REPORT	December 2016
TABLE OF CONTENTS
1.	INTRODUCTION	1
2.	OVERVIEW OF U.S. EPA HEALTH EFFECTS ASSESSMENT METHODS	6
2.1	Non-carcinogens	6
2.2	Carcinogens	9
2.2.1	Classifications	9
2.2.2	Quantification	11
2.3	How U.S. EPA Sets the MCLG and MCL	12
2.3.1	Non-carcinogens	12
2.3.2	Carcinogens	13
2.4	Key Differences in Human Health Assessment Methods Between U.S. EPA and Other
Organizations Discussed in this Document	16
3.	PROCES S FOR EVALUATING CHEMICALS FOR THE SIX-YEAR REVIEW 3	17
3.1	Identification of List A Chemicals (19) For Which The Health Effect Assessment is in Process or
That Are Nominated For Health Assessment	17
3.2	Literature Search Process for the List B Chemicals (42)	17
3.3	Screening Process for List B Chemicals	18
4.	RESULTS	19
4.1	Findings for List A Chemicals with Ongoing EPA Assessments	19
4.2	Findings for List B Chemicals (42)	21
4.2.1	Findings for Consideration of a Change to the MCLG	22
4.2.2	Findings for No Consideration of a Change to the MCLG	25
5.	SUMMARY	26
6.	REFERENCES	28
APPENDIX A -LIST A TOXICITY TABLES FOR SELECTED CHEMICALS INCLUDED IN IRIS
MULTI-YEAR AGENDA	54
APPENDIX B - LIST B TOXICITY TABLES FOR CHEMICALS THAT ARE EVALUATED FOR
POTENTIAL IMPACT ON The MCLG	69
APPENDIX C - HEALTH EFFECTS 01 FLUORIDE	54
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List of Tables
Table 1: List A Chemicals - Health Effects Assessment in Process or Nominated for Health Assessment. 4
Table 2: List B Chemicals - Evaluated for Health Effects to Determine the Potential Impact on the
MCLG	5
Table 3: U.S. EPA Three-Category Approach and Corresponding 1986 Cancer Classification System ... 15
Table 4: List A Chemicals (19) with Ongoing EPA Assessments or Nominated for Assessment	20
Table 5: List B Chemicals with New Data and Potential New MCLG	23
Table 6: Chemicals with No Potential Change to the MCLG	25
Table la. Summary of EPA Assessments: Cadmium CASRN 7440-43-9	55
Table lb. Summary of Assessments by Other Organizations: Cadmium CASRN 7440-43-9	56
Table 2a. Summary of EPA Assessments: 1,2-Dichlorobenzene (o-Dichlorobenzene) CASRN 95-50-1.57
Table 3a. Summary of EPA Assessments: 1,4-Dichlorobenzene (p-Dichlorobenzene) CASRN 106-46-758
Table 3b. Summary of Assessments by Other Organizations: 1,4-Dichlorobenzene (p-Dichlorobenzene)
CASRN 106-46-7	59
Table 4a. Summary of EPA Assessments: Di(2-ethylhexyl) phthalate (DEHP) CASRN 117-81-7	60
Table 4b. Summary of Assessments by Other Organizations: Di(2-ethylhexyl) phthalate (DEHP) CASRN
117-81-7	61
Table 5a. Summary of EPA Assessments: Mercury (Inorganic) CASRN 7439-97-6	62
Table 6a. Summary of EPA Assessments: Nitrate (as N) CASRN 14797-55-8	63
Table 6b. Summary of Assessments by Other Organizations: Nitrate (as N) CASRN 14797-55-8	64
Table 7a. Summary of EPA Assessments: Nitrite (as N) CASRN 14797-65-0	65
Table 7b. Summary of Assessments by Other Organizations: Nitrite (as N) CASRN 14797-65-0	66
Table 8a. Summary of EPA Assessments: Uranium CASRN 7440-61-1	67
Table 8b. Summary of Assessments by Other Organizations: Uranium CASRN 7440-61-1	68
Table la. Summary of EPA Assessments: Alachlor CASRN 15972-60-8	70
Table 2a. Summary of EPA Assessments: Antimony CASRN 7440-36-0	71
Table 3a. Summary of EPA Assessments: Asbestos CASRN 1332-21-4	72
Table 3b. Summary of Assessments by Other Organizations: Asbestos CASRN 1332-21-4 	73
Table 4a. Summary of EPA Assessments: Barium CASRN 7440-39-3	74
Table 5a. Summary of EPA Assessments: Beryllium CASRN 7440-41-7	75
Table 5b. Summary of Assessments by Other Organizations: Beryllium CASRN 7440-41-7	76
Table 6a. Summary of EPA Assessments: Carbofuran CASRN 1563-66-2	77
Table 7a. Summary of EPA Assessments: Chlordane CASRN 12789-03-6 (IRIS), 57-74-9 (lit search) ..78
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Table 8a. Summary of EPA Assessments: Chlorobenzene (Monochlorobenzene)
CASRN 108-90-7	79
Table 8b. Summary of Assessments by Other Organizations: Chlorobenzene (Monochlorobenzene)
CASRN 108-90-7	80
Table 9a. Summary of EPA Assessments: Cyanide CASRN 57-12-5	81
Table 10a. Summary of EPA Assessments: 2,4-Dichlorophenoxyacetic Acid (2,4-D)
CASRN 94-75-7	82
Table 10b. Summary of Assessments by Other Organizations: 2,4-Dichlorophenoxyacetic Acid (2,4-D)
CASRN 94-75-7	83
Table 11a. Summary of EPA Assessments: Dalapon (2,2-Dichloropropionic Acid)
CASRN 75-99-0	84
Table 12a. Summary of EPA Assessments: l,2-Dibromo-3-chloropropane (DBCP)
CASRN 96-12-8	85
Table 12b. Summary of Assessments by Other Organizations: l,2-Dibromo-3-chloropropane (DBCP)
CASRN 96-12-8	86
Table 13a. Summary of EPA Assessments: 1,1-Dichloroethylene CASRN 75-35-4	87
Table 14a. Summary of EPA Assessments: c/s-l,2-dichloroethylene CASRN 156-59-2	88
Table 15a. Summary of EPA Assessments: fra«s-l,2-Dicloroethylene CASRN 156-60-5 	89
Table 16a. Summary of EPA Assessments: Di(2-ethylhexyl) adipate (DEHA) CASRN 103-23-1	90
Table 17a. Summary of EPA Assessments: Dinoseb CASRN 88-85-7	91
Table 18a. Summary of EPA Assessments: Dioxin (2,3,7,8-TCDD) CASRN 1746-01-6	92
Table 18b. Summary of Assessments by Other Organizations: Dioxin (2,3,7,8-TCDD)
CASRN 1746-01-6	93
Table 19a. Summary of EPA Assessments: Diquat CASRN 85-00-7	94
Table 20a. Summary of EPA Assessments: Endothall CASRN 145-73-3 	95
Table 20b. Summary of Assessments by Other Organizations: Endothall CASRN 145-73-3 	96
Table 21a. Summary of EPA Assessments: Endrin CASRN 72-20-8	97
Table 22a. Summary of EPA Assessments: Ethylene dibromide (EDB; 1,2-Dibromoethane)
CASRN 106-93-4	98
Table 22b. Summary of Assessments by Other Organizations: Ethylene dibromide (EDB; 1,2-
Dibromoethane) CASRN 106-93-4 	99
Table 23a. Summary of EPA Assessments: Fluoride CASRN 7782-41-4 	100
Table 24a. Summary of EPA Assessments: Heptachlor CASRN 76-44-8	101
Table 25a. Summary of EPA Assessments: Heptachlor epoxide CASRN 1024-57-3	102
Table 26a. Summary of EPA Assessments: Hexachlorobenzene CASRN 118-74-1	103
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Table 26b. Summary of Assessments by Other Organizations: Hexachlorobenzene
CASRN 118-74-1	104
Table 27a. Summary of EPA Assessments: Hexachlorocyclopentadiene CASRN 77-47-4 	105
Table 27b. Summary of Assessments by Other Organizations: Hexachlorocyclopentadiene
CASRN 77-47-4	106
Table 28a. Summary of EPA Assessments: Lindane (gamma-Hexachlorocyclohexane)
CASRN 58-89-9	 107
Table 28b. Summary of Assessments by Other Organizations: Lindane (gamma-Hexachlorocyclohexane)
CASRN 58-89-9	 108
Table 29a. Summary of EPA Assessments: Methoxychlor CASRN 72-43-5 	109
Table 29b. Summary of Assessments by Other Organizations: Methoxychlor CASRN 72-43-5 	110
Table 30a. Summary of EPA Assessments: Oxamyl CASRN 23135-22-0	Ill
Table 30b. Summary of Assessments by Other Organizations: Oxamyl CASRN 23135-22-0	112
Table 3 la. Summary of EPA Assessments: Pentachlorophenol CASRN 87-86-5	 113
Table 3 lb. Summary of Assessments by Other Organizations: Pentachlorophenol CASRN 87-86-5	 114
Table 32a. Summary of EPA Assessments: Picloram CASRN 1918-02-1	115
Table 33a. Summary of EPA Assessments: Selenium CASRN 7782-49-2	116
Table 33b. Summary of Assessments by Other Organizations: Selenium CASRN 7782-49-2	117
Table 34a. Summary of EPA Assessments: Styrene CASRN 100-42-5	118
Table 34b. Summary of Assessments by Other Organizations: Styrene CASRN 100-42-5	119
Table 35a. Summary of EPA Assessments: Thallium CASRN 7440-28-0 	120
Table 36a. Summary of EPA Assessments: Toluene CASRN 108-88-3	 121
Table 36b. Summary of Assessments by Other Organizations: Toluene CASRN 108-88-3	 122
Table 37a. Summary of EPA Assessments: Toxaphene CASRN 8001-35-2 	 123
Table 37b. Summary of Assessments by Other Organizations: Toxaphene CASRN 8001-35-2	 124
Table 38a. Summary of EPA Assessments: 2,4,5-Trichlorophenoxypropionic Acid (2,4,5-TP; Silvex)
CASRN 93-72-1	125
Table 38b. Summary of Assessments by Other Organizations: 2,4,5-Trichlorophenoxypropionic Acid
(2,4,5-TP; Silvex) CASRN 93-72-1	126
Table 39a. Summary of EPA Assessments: 1,2,4-Trichlorobenzene CASRN 120-82-1	127
Table 39b. Summary of Assessment by Other Organizations: 1,2,4-Trichlorobenzene
CASRN 120-82-1	128
Table 40a. Summary of EPA Assessments: 1,1,1-Trichloroethane CASRN 71-55-6	129
Table 41a. Summary of EPA Assessments: 1,1,2-Trichloroethane CASRN 79-00-5 	 130
Table 42a. Summary of EPA Assessments: Xylenes (Total) CASRN 1330-20-7	 131

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Table 42b. Summary of Assessments by Other Organizations: Xylenes (Total)
CASRN 1330-20-7	 132
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SIX-YEAR REVIEW 3 HEALTH EFFECTS ASSESSMENT:
SUMMARY REPORT
1. INTRODUCTION
The 1996 amendments to the Safe Drinking Water Act (SDWA), Section 1412(b)(9),
require the United States Environmental Protection Agency (U.S. EPA) to review existing
National Primary Drinking Water Regulation (NPDWR) every six years and determine which, if
any, are candidates for revision. The SDWA Amendments also specify that any revision of a
NPDWR will maintain or provide for greater protection of public health. The goal of the cyclical
review is to determine whether it is appropriate to consider changes (i.e., to "revise" or "take no
action") to existing NPDWRs based on changes in health effects and/or analytical or
technological feasibility that have occurred since the regulations were promulgated.
In response to this mandate, U.S. EPA developed a Protocol for the Review of Existing
National Primary Drinking Water Regulations (U.S. EPA, 2002a; 2003e) based on
recommendations of the National Drinking Water Advisory Council (NDWAC, U.S. EPA,
2000a) and input from stakeholders representing a wide variety of interest groups. U.S. EPA has
updated this protocol for the third review effort (U.S. EPA, 2016d). The protocol outlines the
approach to be used to review and identify NPDWRs that may warrant revision. The key
elements that are considered in the review process are health effects, analytical methods,
occurrence and exposure, treatment technology, and other regulatory provisions (e.g., monitoring
and reporting requirements).
The primary purpose of this document is to summarize the results of the review of the
health effects component of the Six-Year Review 3 effort for the chemical and radiological
NPDWRs regulated under the Phase Rules and Radionuclides Rule. Seven NPDWRs fall under
the disinfectants and disinfection byproducts rules (bromate, chloramine [as C12], chlorine [as
C12], chlorine dioxide, chlorite, total trihalomethanes and haloacetic acids). Information on these
contaminants is evaluated in a separate document developed by EPA: Technical Support
Document titled "Technical Support Document for Disinfectants/Disinfection Byproducts
Regulations Under Six-Year Review 3" (USEPA, 2016h).
In addition, turbidity is also not evaluated in this report because it is not a chemical
pollutant and it is covered in a separate document (U.S. EPA, 2016f and 2016g). Finally, five
microbial contaminants/groups are analyzed under Surface Water Treatment Rule (SWTR),
Interim Enhanced SWTR, LT1/LT2 Enhanced SWTR (Cryptosporidium, Giardia lamblia,
Heterotrophic plate count, Legionella, Viruses) separately under 'Technical Support Document
for Microbial Contaminant Regulations Under Six-Year Review 3' (U.S. EPA, 2016f) and under
'Technical Support Document for Long-Term 2 Regulation Under Six-Year Review 3' (U.S.
EPA, 2016g).
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1.1 Background
The Agency completed its first Six-Year Review (referred to here as "Six-Year Review
1") in July 2003 (U.S. EPA, 2002b; 2003a). In the Six-Year Review 1, EPA evaluated the
information available at that time on the key elements of the review process for sixty-eight (68)
chemical contaminants covered under various NPDWRs. The assessment of health effects for
those sixty-eight (68) chemicals was presented in the Six-Year Review, Chemical Contaminants
- Health Effects Technical Support Document (U.S. EPA, 2003f). Five chemicals were identified
as potentially qualifying for revision on the basis of new EPA health assessments independent of
technological feasibility considerations (i.e., analytical and treatment technology) and occurrence
data. These five chemicals were beryllium, 1,1-dichloroethylene, lindane, oxamyl, and picloram.
The Six-Year Review 1 health assessment also identified three chemical contaminants (cyanide,
di(2-ethylhexyl) adipate and thallium) as high priority for reevaluation because of reproductive
and/or developmental information based on the literature search and new assessments available
at that time. Fluoride was also identified as a candidate for reevaluation because of information
on dental, bone and cancer effects. In completing Six-Year Review 1, the Agency determined
that it was not appropriate to revise any of the sixty-eight (68) chemicals NPDWRs considered at
that time (U.S. EPA, 2003a).
The agency completed the health effects review for the second Six-Year Review in
October 2009 (U.S. EPA, 201 Of; 2009c) (referred to here as "Six-Year Review 2"). Under Six-
Year Review 2, the health assessments of seventy-one (71) chemicals were reviewed, including
sixty-six (66) of the sixty-eight (68) chemicals from Six-Year Review 1. Lead and copper were
not included under Six-Year Review 2 because of ongoing efforts initiated in 2006 to revise the
Lead and Copper Rule. However, five chemicals not considered during Six-Year Review 1
(arsenic; uranium; combined radium [226 and 228]; alpha particle emitters; and beta particle and
photon emitters), for which new regulations had been promulgated, were considered during Six-
Year Review 2.
During Six-Year Review 2, new EPA health assessments were identified that could
impact MCLGs for 14 contaminants (alachlor, barium, 2,4-D (2,4-dichlorophenoxyacetic acid),
1,1-dichloroethylene, diquat, endothall, glyphosate, hexachlorocyclopentadiene, lindane, oxamyl
(vydate), picloram, toluene, 1,1,1-trichloroethane, and xylenes (total)). It should be noted that the
identification of chemicals qualifying for revision was independent of other considerations (e.g.,
analytical and treatment technology, occurrence data) that may have influenced the final
selection of contaminants to be revised. EPA also identified five contaminants (chromium,
nitrate, nitrite, selenium, and 1,2,4-trichlorobenzene) for which new literature was available
supporting the potential need for new health effects assessments and two contaminants (atrazine
and simazine) that warranted further evaluation based on availability of new health effects data
(U.S. EPA, 2009c).
Considering analytical methods, technology and other factors along with health
assessments during Six-Year Review 2, EPA identified four NPDWR chemical contaminants as
candidates for revision. The four NPDWRs were: acrylamide, epichlorohydrin,
tetrachloroethylene, and trichloroethylene.
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1.2 Six-Year Review 3
The decision-making process of the Six-Year Review 3 protocol was essentially the same
as that implemented during Six-Year Review 1 and Six-Year Review 2, however a modification
to the protocol was included in this cycle of review. For the Six-Year Review 1 and Six-Year
Review 2, only EPA assessments were evaluated for their potential impact on maximum
contaminant level goal (MCLG) revisions. The non-EPA assessments (e.g., Agency for Toxic
Substances and Disease Registry (ATSDR), California Environmental Protection Agency
(CalEPA), and Health Canada) were reviewed but not included in the consideration of potential
revisions to the MCLG. For the Six-Year Review 3, these non-EPA assessments were taken into
consideration as the basis for potential MCLG revisions, as appropriate. The EPA Integrated
Risk Information System (IRIS) and the Office of Pesticide Programs (OPP) became the
predominant sources for reference dose and cancer slope factors for this update. For a few
contaminants, however, more recent toxicity assessments from federal, state and international
agencies provided the assessments that identified potential revisions to MCLGs.
After identifying and documenting all available toxicity values, EPA selected the toxicity
values for non-carcinogenic and carcinogenic effects that could potentially change an existing
MCLG. A more current toxicological assessment from a source other than EPA was selected
when these assessments introduced new science (e.g., the toxicity value was based on a newer
principal study) or used a more current approach for dose-response quantification. Final
decisions about potential changes to an MCLG take into account information beyond
consideration of toxicity (e.g., occurrence and exposure, treatment technologies, analytical
methods).
Beginning with the National Interim Primary Drinking Water Regulations (U.S. EPA,
1976), MCLGs have been typically derived using an adult body weight of 70 kg and drinking
water intake of 2 L per day. The body weight assumption of 70 kg, was supported by the mean
bodyweight of adults from the NHANES III database (1988-1994) and a 1989 study conducted
by the National Cancer Institute (Section 4.3.1 in U.S.EPA, 2000b). The drinking water intake
rate of 2 L/day was also first selected for use in development of the National Interim Primary
Drinking Water Regulations (U.S. EPA, 1976) considering the data available at the time.
Support to this value is provided by the consumers only community water ingestion rate for
adults surveyed in the U.S. Department of Agriculture's 1994-1996 Continuing Survey of Food
Intake by Individuals (CSFII) analysis (USEPA 2000b, section 4.3.2.1). Updates to the drinking
water intake and body weight parameters are provided in EPA's Exposure Factors Handbook
(U.S. EPA, 201 la) supporting a revision for the 90th percentile consumers only tap water intake
to 2.5 L per day and the mean adult body weight to 80 kg, respectively. This review focuses
primarily on the impact of new toxicity data in evaluating changes to MCLGs, and thus
comparisons have been made using the older body weight and tap-water intake assumptions. The
net effect of adjusting these values would be less than a 9% reduction in the MCLGs. In a few
cases (e.g., carbofuran, oxamyl), where the most recent toxicity values were derived for infants
and children, the potential MCLGs were calculated based on children's body weight and water
intake for the first year of life.
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Under Six-Year Review 3, the initial review identified 12 Chemical Phase Rule
NPDWRs that were being considered as part of ongoing or pending regulatory actions. These 12
NPDWRs included:
•	Eight chemicals (benzene, carbon tetrachloride, 1,2-dichloroethane, dichloromethane,
1,2-dichloropropane, tetrachloroethylene, trichloroethylene, and vinyl chloride) are being
evaluated as part of the Group Regulation of Carcinogenic Volatile Organic Compounds
(cVOCs) (U.S. EPA, 2011b; U.S. EPA, 2014b).
•	Copper and lead are being evaluated in an ongoing effort to revise the Lead-Copper
Rule/NSDWR (U.S. EPA, 199If and 2007a)
•	Acrylamide and epichlorohydrin were identified as candidates for revisions in Six-Year
Review 2 (U.S. EPA, 2010f) and were pending regulatory revision. For the technical
analysis for these two contaminants, see Support Document for Third Six Year Review of
Drinking Water Regulations for Acrylamide and Epichlorohydrin (U.S. EPA, 2016e).
EPA determined that for 19 NPDWRs, a USEPA health effects assessment is currently in
process or planned by the Office of Research and Development program Integrated Risk
Information System (IRIS), the Office of Pesticide Programs (OPP), the Office of Radiation and
Indoor Air (ORIA), the Office of Water (OW), or the National Academy of Sciences (assessment
commissioned by USEPA). Therefore, additional health effects reviews for those chemicals as
part of Six-Year Review 3 were not necessary. The 19 chemicals (List A) are identified in Table
1.
Table 1: List A Chemicals - Health Effects Assessment in Process or Nominated for Health
Assessment
Alpha/photon emitters
Di(2-ethylhexyl) phthalate
(DEHP)
Nitrite
Arsenic, inorganic
1, 2 Dichlorobenzene
Polychlorinated biphenyls
(PCBs)
Atrazine
1,4 Dichlorobenzene
Radium (226, 228)
Benzo(a)pyrene (PAH)
Ethylbenzene
Simazine
Beta/photon emitters
Glyphosate
Uranium
Cadmium
Mercury

Chromium (VI) as part of
total Cr)
Nitrate

EPA's OPP is conducting reviews of atrazine, simazine, and glyphosate in Registration
Review.
EPA's Office of Research and Development is reviewing (or plans to review) inorganic
arsenic, benzo(a)pyrene, chromium (VI), ethylbenzene, cadmium, di(2-ethylhexyl) phthalate
(DEHP), mercury, nitrate, nitrite, 1,2-dichlorobenzene, 1,4-dichlorobenzene, PCBs and uranium
through the IRIS program. Inorganic arsenic, benzo(a)pyrene, chromium, and PCBs are currently
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under review and the remaining chemicals are included in the current IRIS multiyear plan. (U.S.
EPA, 2015). For the purpose of the Six-Year Review 3, these chemicals were considered as
having ongoing assessments and placed on List A.
Following the promulgation of the final radionuclides rule (U.S. EPA, 2000c), additional
information became available on the adverse health effects of ionizing radiation (including alpha
particle emitters; beta particle and photon emitters; and combined radium (226 and 228)), as well
as for the mechanisms that cause cellular and molecular damage. In light of this new
information, EPA's ORIA has begun the process of revising its radiation risk methodology to
incorporate the new data, (U.S. EPA, 2007b, 2007c, 2007d).
The following forty-two (42) chemicals, identified as List B (Table 2) underwent a more
detailed review including the evaluation of effects and risk-based values from government
agencies and publications from the primary literature. This document summarizes the results of
the review of the health effects component of the Six-Year Review 3 effort for the chemicals
identified below.
Table 2: List B Chemicals - Evaluated for Health Effects to Determine the Potential
Impact on the MCLG
Alachlor
Ethylene Dibromide (EDB;1,2-

Dibromoethane)
Antimony*
Fluoride
Asbestos*
Heptachlor
Barium
Heptachlor epoxide
Beryllium*
Hexachl orob enzene
Carbofuran
Hexachl orocy cl opentadi ene
Chlordane
Lindane (gamma-hexachloro-cyclohexane)
Chlorobenzene (Monochlorobenzene)
Methoxychlor
Cyanide, free*
Oxamyl (Vydate)
2,4-D (2,4-Dichlorophenoxy Acetic Acid)
Pentachlorophenol *
Dalapon (2,2-Dichloropropionic Acid)
Pi cl oram
l,2-Dibromo-3-chloropropane (DBCP)
Selenium
1,1 -Dichloroethylene
Styrene*]}
cis-1,2-Dichloroethylene*
Thallium*
trans-l ,2-Dichloroethylene*
Toluene
Di(2-ethylhexyl) adipate (DEHA)*
Toxaphene
Dinoseb
2,4,5-TP (Silvex; 2,4,5

Trichlorophenoxypropionic Acid)
Dioxin*
1,2,4-Tri chlorobenzene
Diquat
1,1,1-Trichl oroethane
Endothall
1,1,2-Trichl oroethane
Endrin
Xylenes (total)
*Not reviewed during Six-Year Review 2 because of ongoing assessments
^Included in IRIS Multi-year agenda (U. S. EPA 2015), but is included in List B based on a Cal-EPA
Assessment
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1.3 Objectives and Report Organization
The first objective of the review was to identify new quantitative and qualitative health
information that could indicate a possible basis for revising the MCLG when supported by
occurrence data and technological feasibility. The second objective of the review was to identify
chemicals that might warrant a new formal Agency health effects assessment or further follow-
up and evaluation based on the availability of significant new health information identified
through the literature searches.
Section 2 provides an overview of U.S. EPA health effects assessment methods, for both
carcinogens and non-carcinogens, that are relevant to the health effects assessments conducted
under this Six-Year Review.
Section 3 describes the overall process implemented to evaluate any new health effects
for chemicals considered in this Six-Year Review.
Section 4 presents the results of the health effects review, including the identification of
those chemicals for which OW identified new health risk assessment that suggested a possible
change to the current MCLG could be considered.
Section 5 provides an overall summary of this document.
2. OVERVIEW OF U.S. EPA HEALTH EFFECTS ASSESSMENT METHODS
2.1 Non-carcinogens
For chemicals exhibiting a threshold for toxic effects, U.S. EPA establishes the MCLG
based on an oral reference dose (RfD). The MCL is the same as the MCLG in cases where it is
technically feasible based on quantitation levels and treatment technology, and can be achieved
at a cost commensurate with the benefits achieved. A change in the RfD could lead to a change
in the MCLG. The RfD is an estimate (with uncertainty spanning perhaps an order of magnitude)
of a daily oral exposure to the human population (including sensitive subgroups) that is likely to
be without an appreciable risk of deleterious non-cancer effects during a lifetime. The RfD is
derived as follows:
RfD (mg/kg/day) = NOAEL or LOAEL or BMDL
UF
where:
NOAEL = no-observed-adverse-effect level (mg/kg/day)
LOAEL = lowest-observed-adverse-effect level (mg/kg/day)
BMDL = lower confidence limit on the benchmark dose (mg/kg/day)
UF = uncertainty factor
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No-Observed-Adverse-Effect Level (NOAEL): The highest exposure level at which there are
no biologically significant increases in the frequency or severity of adverse effect between the
exposed population and its appropriate control; some effects may be produced at this level, but
they are not considered adverse or precursors of adverse effects.
Lowest-Observed-Adverse-Effect Level (LOAEL): The lowest exposure level at which there
are biologically significant increases in frequency or severity of adverse effects between the
exposed population and its appropriate control group.
Benchmark Dose Lower confidence limit (BMDL): Benchmark dose (BMD) modeling can be
performed to identify a dose level that causes a defined level of change in the critical effect in
cases where the study doses have a different level of change than the one that defines an effect as
adverse. Since the BMD modeling and the determination of the BMD and BMDL is dependent
on a predetermined change in response rate of an adverse effect compared to background (or the
benchmark response (BMR)), it is critical to select an appropriate BMR in the BMD modeling
process. For quantal data, an excess risk of 10% generally has been the default BMR because the
10% response is at or near the limit of sensitivity in most cancer and noncancer bioassays. If a
study has greater-than-usual sensitivity, then a lower BMR can be used, although the benchmark
dose at a 10% response (BMDio) and the lower 95% confidence limit on the BMDio (BMDLio)
are usually presented for comparison purposes. For continuous data, if there is a minimal level of
change in the endpoint that is generally considered to be biologically significant, then that
amount of change can be used to define the BMR. In the absence of any other data on the
adverse response level, a change in the mean equal to one control standard deviation (1SD) from
the control mean is generally used (U.S. EPA, 2000d; 2012a).
BMD modeling is an alternative approach for deriving RfDs instead of using a NOAEL or
LOAEL. The BMDL is a dose that is determined by fitting a flexible mathematical model to the
data. The BMD is the central estimate of that dose, and the BMDL is the corresponding lower
limit of a one-sided 95% confidence interval on the BMD. In practice, the BMDL is often used
as an alternative to the NOAEL as a point of departure in recent noncancer risk assessments.
Selecting BMRs involves making judgments about the statistical and biological characteristics of
the dataset (e.g., quantal versus continuous) and about the applications for which the resulting
BMDs/BMDLs will be used.
Uncertainty Factors (UF): The NOAELs, LOAELs or BMDLs selected for deriving the RfD
can be determined from animal or human data. In calculating an RfD, the NOAEL, LOAEL or
BMDL is divided by a composite uncertainty factor (UF). An UF is a product of several
uncertainty factors accounting for variation in sensitivity among members of the human
population, extrapolation from animal data to humans, extrapolation from a LOAEL to a
NOAEL, extrapolation of subchronic data to lifetime, and database deficiencies. Each individual
UF presented below may range between 1 and 10 to account for the uncertainty introduced either
by variability or the absence of information. The specific magnitude of the value is based upon a
combination of scientific evidence and professional judgment (U.S EPA, 2002c).
Some older assessments also used a modifying factor (MF) in the calculation of the overall UF.
Discontinuation of the MF was recommended in 2002 (U.S. EPA, 2002b), and the IRIS glossary
states that the MF was discontinued in 2004. The magnitude of the MF reflected the scientific
uncertainties of the study and database not explicitly treated with standard uncertainty factors
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(e.g., the completeness of the overall database). Current practice is to address those uncertainties
in the database uncertainty factor. A MF was greater than zero and less than or equal to 10, and
the default value for the MF was 1. Based on the EPA guidance for RfD determination, the total
UF may not exceed 3000 (U.S. EPA, 2002c).
The following paragraphs describe the component uncertainty factors, based on current U.S.
EPA guidance for use of uncertainty factors for IRIS and similar programs. In addition to the
considerations suggested below, others may be appropriate depending upon data availability,
applicability, and quality. In particular, additional considerations are used in deriving an RfD for
nutritionally essential elements, taking into account recommended intake.
UFh (human to sensitive human): A factor of 10 is used as the default when data from
human populations are lacking or deficient, as well as when the data are from studies on
average healthy humans. A factor of 3 can be used when the sensitivity of the human
population used in the study is judged to be between that for sensitive and average
healthy humans, such as when some, but not all, significant contributors to sensitivity are
addressed, or when the study population is large enough to capture significant population
variability. Chemical-specific data can also be used to adjust this factor, when adequate
data are available. A factor of 1 is used when the data are from a good-quality
epidemiology study evaluating effects in a sensitive population.
UFa (animal to human): A factor of 10 is used as the default when extrapolating valid
results from experimental animal studies, when results of studies of human exposure are
not available or are inadequate. A factor of 3 can be used when results are obtained from
an animal species that is physiologically similar to humans, such as nonhuman primates,
or when pharmacokinetic modeling approaches are used in extrapolating from the animal
data (U.S. EPA, 1994c). Chemical-specific data can also be used to adjust this factor,
when adequate data are available. A factor of 1 can be used when valid results are
obtained from an animal species that is known to be more sensitive than humans to the
chemical of interest, or when comparative metabolic and/or toxicity data show that the
experimental animal responds to the chemical or agent in a manner that is the same or
very similar to the way that a human responds.
UFt (LOAEL to NOAEL): A factor of 10 is used as the default when deriving an RfD
from a LOAEL instead of a NOAEL. A factor of less than 10 (typically 3) can be used
when there is sufficient evidence to suggest that the LOAEL used is based on an effect of
minimal adversity or in a case where the dose response for the collection of similar
studies demonstrates that the difference between an effect and no effect level is less than
10. A factor of 1 is used when the critical effect level is a study NOAEL or when
benchmark dose modeling (i.e., a BMDL) was used to identify the point of departure. The
BMDL has been used as an alternative to the NOAEL as a point of departure in
noncancer risk assessment.
UFs (subchronic to chronic): A factor of 10 is used as the default when less-than-chronic
results (NOAEL or LOAEL) in humans or experimental animals are used in the absence
of useful long-term human or animal data. A factor of 3 may be used for intermediate
data, such as when some data on chronic exposures are available but the study did not
evaluate some of the parameters shown to be affected in studies of shorter duration. A
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factor of 1 is used when the RfD is derived from a chronic study. A factor of 1 also can
be used when less-than-chronic results are used, if it is known that the subchronic study is
more sensitive than any chronic studies, or that the critical study evaluated the full
duration of relevance for the critical effect (e.g., for certain reproductive or
developmental effects or relevant acute effects such as cholinesterase inhibition).
UFp (completeness of database): This UF is used when deriving a risk value from an
"incomplete" database. The intermediate factor of 3 is often used when there is a single
data gap (e.g., missing a multigenerational reproduction study, or missing a systemic
toxicity study in one species).
The minimum database for a high confidence RfD includes two systemic toxicity studies
of chronic or subchronic duration in different species, a two-generation reproductive
study, and two developmental toxicity studies in different species. For the systemic
toxicity studies, the key consideration is whether a range of endpoints was evaluated;
duration extrapolation, if relevant, is addressed by UFs. The minimum dataset for a low
confidence chronic RfD is a single subchronic study (U.S. EPA, 2002c). Note that U.S.
EPA did not generally use the UFd prior to approximately 1998. The exception was the
where database deficiencies were addressed with the use of a modifying factor, as
discussed above. After 1998, the UFd was adopted by the IRIS program, but the UFd was
not used for regulations by OW until 1997, when some chemicals were assigned database
factors. Therefore, some older RfDs that were developed by U.S. EPA based on
incomplete databases might be 3- to 10-fold lower if current uncertainty factor guidelines
were followed. This is the case for several regulated chemicals that have since been
reevaluated by IRIS or the Office of Pesticide Programs (OPP) resulting in the addition of
a UFd to the Total UF for the same critical effects and point of departure as the one used
for the regulation.
2.2 Carcinogens
U.S. EPA's health effects assessment for carcinogens involves assessing both the weight
of evidence for carcinogenicity and the potency. This section presents U.S. EPA's guidance for
assessing carcinogens as it has evolved from the 1986 guidelines (U.S. EPA, 1986i) through the
final 2005 guidelines (U.S. EPA, 2005a, 2005e).
2.2.1 Classifications
Under the 1986 guidelines, the qualitative assessment began with a separate evaluation of
the animal and human data, identifying the data as sufficient, limited, inadequate, "no data," or
"no evidence of carcinogenicity." The animal and human data were combined with other
available data for an overall weight-of-evidence evaluation, using the following groups:
Group A - Human carcinogen
Group B - Probable human carcinogen
B1 "limited" evidence of carcinogenicity based on epidemiology data, and
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B2 "sufficient" evidence of carcinogenicity from animal data, but
"inadequate" or "no data" in humans
Group C - Possible human carcinogen
Group D - Not classifiable as to human carcinogenicity
Group E - Evidence of non-carcinogenicity for humans
Proposed revisions to the 1986 cancer guidelines were released in 1996 and 1999 (U.S.
EPA, 1996, 1999) as interim guidelines and both revisions were applied to official final U.S.
EPA assessments. Other interim cancer guidelines were published but not used in official final
U.S. EPA assessments. These revised versions of the guidelines, like the current guidelines
(finalized in 2005) described below, emphasized the use of descriptors coupled with a narrative
based on the entire weight of evidence (rather than a cancer classification), and emphasized
mode of action (MO A). However, the 1996 and 1999 versions used somewhat different sets of
descriptors and different definitions of the data supporting each descriptor than the 2005
guidelines. Under the proposed 1996 guidelines, there were just three broad categories of
descriptors: known/likely, cannot be determined, and not likely. Under the draft 1999 guidelines
there were five categories of descriptors: carcinogenic to humans; likely to be carcinogenic to
humans; suggestive evidence of carcinogenicity, but not sufficient to assess human carcinogenic
potential; data are inadequate for an assessment of human carcinogenic potential; and not likely
to be carcinogenic to humans. The 1996 proposed and 1999 draft guidelines were also generally
consistent with the 2005 approach to quantitation (see Section 2.2.2), although they differed in
some minor details with respect to the modeling and the terminology used to identify the point of
departure (ED vs BMD).
Under the 2005 guidelines, a descriptive weight of evidence judgment is made, based on
all available animal, human, and mechanistic data, as to the likelihood that an agent is a human
carcinogen and the conditions under which the carcinogenic effects may be expressed. Under the
2005 guidelines, descriptive terms for carcinogenicity replaced the terms used in the 1999 draft
guidelines, which themselves replaced the 1986 alphanumeric cancer group designations as
described above. A cancer narrative is also included under the 2005 guidelines to provide a more
complete description of the weight of evidence and conditions of carcinogenicity. The suggested
descriptive terms under the 2005 guidelines are as follows:
Carcinogenic to humans
Likely to be carcinogenic to humans
Suggestive evidence of carcinogenic potential
Inadequate information to assess carcinogenic potential
Not likely to be carcinogenic to humans
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Compound descriptors are possible if a chemical has different carcinogenic responses
with different routes of exposure, dose, or MOA1. MOA information enters into both the
qualitative and quantitative portions of the assessment. The MOA determines such issues as the
human relevance of the observed tumors and any route-specific differences (e.g., carcinogenic in
the respiratory tract via the inhalation route, but not carcinogenic via the oral route). MOA must
be considered separately for every target organ. Because of these considerations, one cannot
directly translate the cancer classifications and risk values under the 1986 guidelines to narrative
statements and risks under the 2005 guidelines. A full consideration of the weight of evidence,
including consideration of any available MOA data, would be needed for an assessment under
the 2005 guidelines.
The cancer classifications in this screening-level health review for Six-Year Review 3
chemicals are based only on the Agency's most recent available formal risk assessments. Note
that U.S. EPA cancer assessments conducted between 1996 (following publication of the
proposed guidelines) and 2001, when the Agency published a Federal Register notice (60 FR
59594) authorizing use of the 1999 draft guidelines on an interim basis, often presented two sets
of cancer classifications - one following the 1986 guidelines, and one following the
classification system of the then-most current official version of the pre 2005 guidelines. OPP
assessments conducted during that time period only used the 1986 guidelines.
2.2.2 Quantification
The quantitative aspect of cancer assessment also changed between the 1986 and 2005
guidelines. Under the 1986 guidelines, the cancer risk was calculated by fitting a model to the
tumor data, and then calculating a 95% upper confidence limit on one of the coefficients in the
model. The Linear Multistage Model was the one used most frequently; a few chemicals were
quantified based on other risk models. The resulting number was the ql * (also known as the
slope factor), producing an upper bound on the risk. In addition, in the 1986 guidelines, human
equivalent doses were estimated from animal data using a scaling factor of body weight to the
2/3 power.
Under the 2005 guidelines, a two-step process is used for the quantitation step. First, a
model is used to fit a dose-response curve based on the doses and associated tumors from the
cancer bioassay. The model is used to identify the point of departure (POD), i.e. the dose that is
used for extrapolation to the low-dose region based on the BMD associated with a significant
increase in tumor incidence above the control. According to the 2005 guidelines, the POD is the
lowest dose that is adequately supported by the data. The ED 10 (the dose corresponding to a
10% increase in tumors), and the LED 10 (the 95% lower confidence limit on that dose) are also
reported, and are often used as the POD. Some of the more recent assessments use the
BMD/BMDL terminology rather than the ED/LED terminology. In the 1996 guidelines and in all
later versions, the default for calculating human equivalent dose for oral exposure uses a scaling
factor of body weight to the 3/4 power.
1 Mode of action is defined as a sequence of key events and processes, starting with interaction of an agent with a
cell, proceeding through operational and anatomical changes, and resulting in cancer formation. It is contrasted with
"mechanism of action," which implies a more detailed understanding and description of events.
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In the second step of the low-dose extrapolation, one extrapolates from the POD to the
low-dose region of interest for environmental exposures. The approach for extrapolation depends
on the MO A for carcinogenesis. If the chemical causes cancer through a mutagenic change to
DNA, or if the MOA for causing cancer is not known, this extrapolation is conducted by drawing
a line from the POD to the origin (zero dose, zero tumors, corrected for the background
response). The slope of the line gives the unit risk (risk per unit dose, or risk per [mg/kg/day]). If
there was a positive tumor response at all bioassay doses, the calculated slope is often very
similar to that calculated using the ql* approach. In addition, under the supplemental guidance
(U.S. EPA, 2005e), affirmative determination of a mutagenic MOA (as opposed to defaulting to
a mutagenic MOA based on insufficient data or limited data indicating potential mutagenicity)
determines if ADAFs are applied in the quantification of risk to account for additional sensitivity
of children.
If the chemical is shown to cause cancer via a MOA that is not linear at low doses, and
the agent does not demonstrate mutagenic or other activity consistent with linearity at low doses,
a nonlinear extrapolation is conducted. In earlier versions of the cancer guidelines (U.S. EPA,
1996, 1999) the point of departure was compared to the exposure of interest, resulting in a
margin of exposure (MOE). However, these earlier guidelines did not define the acceptable
MOE value. The 2005 guidelines state that "where tumors arise through a nonlinear MOA, an
oral reference dose or inhalation reference concentration, or both, should be developed in
accordance with U.S. EPA's established practice of developing such values, taking into
consideration the factors summarized in the characterization of the POD." In these cases, an
RfD-like value is calculated based on the key event2 for carcinogenesis or the tumor response.
2.3 How U.S. EPA Sets the MCLG and MCL
Because the identification of contaminants for possible revision based on health effects is
dependent on whether or not the MCLG could change, a brief explanation of the derivation of
the MCLG is warranted. The MCLG is the maximum level of a contaminant in drinking water at
which no known or anticipated adverse health effects occur, allowing for an adequate margin of
safety. As the name implies, an MCLG is a health goal; it is not an enforceable standard. The
MCL is the maximum permissible level of a contaminant in water that is delivered to any user of
a public water system, and it is an enforceable standard. The MCL is set as close as feasible to
the MCLG, taking cost onto consideration and technical factors such as the minimal reporting
level of the analytical method and treatment technology limitations.
As discussed in the next two sections, there are different approaches used to establish
MCLGs for carcinogens and non-carcinogens.
2.3.1 Non-carcinogens
For non-carcinogens, the MCLG is derived from the RfD, which was discussed in
Section 2.1. From the RfD, a Drinking Water Equivalent Level (DWEL) can be determined. A
DWEL is a drinking water lifetime exposure level, assuming 100% exposure from that medium,
2 The key event is defined as an empirically observed precursor step that is itself a necessary element of the mode of
action or is a biologically based marker for such an element.
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at which adverse, non-carcinogenic health effects would not be expected to occur. The DWEL is
derived as follows:
DWEL (mg/L) = RfD x BW
DWI
where:
BW = Body Weight (70 kg for adults, 10 kg for children3)
DWI = Drinking water intake (2 L/day for adults, 1 L/day for children3).
The MCLG is then derived by considering other known or potential sources of exposure,
using the relative source contribution (RSC) factor.
MCLG (mg/L) = DWEL x RSC
The RSC from drinking water is based on actual exposure data, or, if data are not
available, a value of 20% is assumed for effects based on lifetime exposure. This allows 80% of
the total exposure to come from sources other than drinking water, such as exposure from food,
inhalation, or dermal contact. For the few MCLGs based on adverse effects related to exposure
in children, an RSC of 100% was usually applied because the source of exposure for the critical
study was drinking water. In assessments completed after the EPA (2000b) RSC decision tree
was published in the Human Health Ambient Water Quality Criteria Methodology, a maximum
RSC value of 80% allows for potential unidentified sources even when data from other sources
are available.
2.3.2 Carcinogens
For drinking water contaminants regulated prior to the 1996 SDWA, OW followed a
three-category regulatory cancer classification system (Categories I, II, or III). These categories
specify decisions as to degree of concern for an agent's carcinogenic potential as a contaminant
of drinking water, and define to some extent the approach to risk management that is taken for
establishing MCLGs.
U.S. EPA also used the six alphanumeric categories (A, Bl, B2, C, D, and E) of the 1986
cancer guidelines (U.S. EPA, 1986i) in establishing MCLGs. The six-group classification system
is often equated to the three-category system in the NPDWR Federal Register announcements.
Table 1 describes the three categories and, with few exceptions (e.g., beryllium), their usual
equivalent alphanumeric classification. If a chemical was a known or probable human
carcinogen by the oral route (Category I, generally Group A or B), the MCLG was generally set
at zero because it is assumed, in the absence of other data, that there is no known threshold for
carcinogenicity. If a chemical is in Group C (Category II), the MCLG was derived using the RfD
3 The 70 kg body weight and consumers only drinking water intake (90th percentile) of 2L/day were used for most
currently regulated chemicals. The comparable values in the EPA (201 la) Exposure Factors Handbook are 80 Kg
and 2.5 L/day. The values for children (a one year infant) have also changed. For children, the normalized drinking
water intakes per unit body weight over the first year of life is 0.15L/Kg based on the 90th percentile of drinking
water consumption and the mean body weight for age groups, birth to <1 month, 1 to <3 months, 3 to <6 months, 6
to <12 months rather than the 0.1 ratio used for earlier assessments.
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approach, as described in the next section, along with an additional risk management safety
factor of 1 tolO. If a chemical is placed into Group D or E (Category III), the MCLG was derived
using the RfD approach as described in the next section. The methodology used under this
approach for establishing MCLGs for chemicals with varying degrees of evidence of
carcinogenicity is summarized in Table 3.
A generally similar approach applies to chemicals with cancer assessments developed
under more recent U.S. EPA guidelines. The MCLG is generally set at zero for chemicals with a
descriptor of carcinogenic to humans or likely to be carcinogenic to humans. For a descriptor of
suggestive evidence of carcinogenic potential, the RfD approach is used.
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Table 3: U.S. EPA Three-Category Approach and Corresponding 1986 Cancer
Classification System
Three-category approach for
Corresponding five-group classification
establishing MCLGs
system of 1986 cancer guidelines
MCI.G generally set al zero
Category I:
Generally Group A or B:
Known or probable human
A: Human carcinogen
carcinogens: Strong evidence of
Sufficient evidence from epidemiological studies
carcinogenicity
to support a causal association.

B: Probable human carcinogen
Sufficient human or animal evidence of
B1: Limited evidence of carcinogenicity from
carcinogenicity.
epidemiological studies.

B2. Inadequate evidence or no data from

epidemiological studies; sufficient evidence from

animal studies.
MCI.G based on (lie Kl'l) with an additional safely factor of up lo 10 lo account Im-
possible carcinogenicity, or is based
on excess cancer risk range of 10° lo 10 ''
Category II:
Generally Group C:
Limited evidence of carcinogenicity
Possible human carcinogen
Some limited but insufficient evidence of
Limited evidence of carcinogenicity in animals in
carcinogenicity from animal data.
the absence of human data.
MCI.G established
using the Kl'l) approach
Category III:
Group D or Group E:
Inadequate or no evidence of
D: Not classifiable as to human carcinogenicity
carcinogenicity in animals
Inadequate human and animal evidence of

carcinogenicity, or no data available.

E: Evidence of non-carcinogenicity for

humans

No evidence of carcinogenicity in two different

animal species, or in both epidemiological and

animal studies.
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2.4 Key Differences in Human Health Assessment Methods Between U.S. EPA and Other
Organizations Discussed in this Document
As part of the evaluation of the List B chemicals, assessments by several other regulatory
bodies or authoritative organizations were reviewed. Notable among these are the ATSDR,
CalEPA, the World Health Organization (WHO), Health Canada, and NAS. To provide context
to that review, key differences between the human health assessment methods of these other
organizations and those of U.S. EPA are summarized here.
ATSDR establishes oral minimal risk levels (MRLs) for non-cancer endpoints for acute
(1-14 days), intermediate (15-364 days), and chronic (365 days or more) exposure durations.
MRLs for oral chronic exposure are derived using approaches similar to U.S. EPA's RfDs.
However, ATSDR and EPA use different approaches when the database is limited to subchronic
studies and no adequate chronic study is available. In such cases, U.S. EPA derives a chronic
RfD from a subchronic study, incorporating an additional uncertainty factor to account for use of
a subchronic study. ATSDR derives an intermediate duration MRL and it generally does not
derive a chronic oral MRL by incorporating an additional uncertainty factor to account for using
a less-than-lifetime study. For cancer effects, ATSDR cites the cancer classification of National
Toxicology Program (NTP), EPA and International Agency for Research on Cancer (IARC) in
the toxicological profiles. ATSDR does not perform quantitative cancer risk assessments or
assign formal cancer classifications or descriptors, although an overall summary of the data
pertaining to carcinogenic potential is provided.
Cal EPA establishes a public health goal (PHG), which is a water concentration that is the
State's equivalent to the MCLG. The PHG can be based on either cancer or noncancer endpoints.
When the PHG is based on cancer endpoints, Cal EPA estimates a cancer potency factor and
then uses the potency factor to estimate the daily water intake that is equivalent to a 10"6 cancer
risk, utilizing lifestage adjusted drinking water intake and drinking water equivalent exposures
that include exposures from inhalation and dermal routes from bathing and showering. When the
PHG is based on noncancer endpoints, the reference value, called Acceptable Daily Intake, may
utilize a point of departure derived using EPA's BMD modeling. A total uncertainty factor of
3000 may be utilized, with intrahuman variability of up to 3 Ox compared to 1 Ox by U.S. EPA.
The PHG for noncancer effects sometimes also includes a drinking water intake rate adjusted to
lifestages and inhalation and dermal route exposures from bathing and showering. Cal EPA uses
a default RSC of 20%, similar to the approach of U.S. EPA, but uses other data-derived values
more frequently than does U.S. EPA.
WHO establishes a "guideline value," a drinking water concentration that is developed in
a process analogous to that for the MCLG. However, WHO uses different default assumptions
for estimating water concentration, including a 60 kg adult body weight, along with the
traditional daily water consumption of 2 L/day and the default RSC of 20%. The guideline value
can also address infant and child water consumption differences and changes to RSC as allowed
by the data. WHO develops one guideline value that is based either on cancer or noncancer
endpoints. For genotoxic carcinogens a value may be based on a concentration calculated to
correspond to a cancer risk, usually 10"5. WHO also states that member states can make
adjustments by a factor of 10 above and below that 10"5guideline value.
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Health Canada concludes that for substances with no threshold (i.e., mutagens and
genotoxic carcinogens), it is assumed that there is some probability of harm to human health at
any level of exposure. Health-based values for carcinogens are generally established on the basis
of an estimation of lifetime cancer risk that would be considered "essentially negligible," which
Health Canada has defined in the context of drinking water guidelines as a range from one new
cancer above background per 100,000 people to one new cancer above background per
1,000,000 people (i.e., 10"5 to 10"6) over a lifetime of 70 years. For non-carcinogens, an approach
similar to U.S. EPA's RfD methodology is used (U.S. EPA, 2002c). For calculating water
concentrations, default values of 70 kg body weight, 1.5 L water intake per day, and a RSC of
either 20% or a value based on actual exposure data are used. In the case of volatile compounds
(both carcinogenic and non-carcinogenic), Health Canada employs a multi-route exposure
approach to estimate the relative contribution of the inhalation and dermal exposures during
showering and bathing. Using this approach, litre-equivalent contributions are estimated for both
the inhalation and dermal routes of exposure which are then added to the daily oral water intake
to reflect an overall daily intake from all potential routes of exposure for drinking water.
3. PROCESS FOR EVALUATING CHEMICALS FOR THE SIX-YEAR REVIEW 3
3.1	Identification of List A Chemicals (19) For Which The Health Effect Assessment is in
Process or That Are Nominated For Health Assessment
These 19 List A chemicals in Table 1 have an ongoing U.S. EPA health assessment in
process or have been nominated for a health assessment (as of 12/2015). The review of the List
A chemicals/radionuclides was limited to evaluation of available non-cancer and cancer
assessments from the following sources: EPA OW, IRIS, ORIA, and OPP Reregi strati on
Eligibility Decisions (RED), to determine if there were new data that should be considered
during the Six-Year Review 3. In addition, qualitative and quantitative descriptions of the toxic
and cancer effects from U.S. EPA documents for which external review versions are available
were also reviewed, with the understanding that these external-peer-review-ready assessments
are subject to further changes. No additional literature search was conducted for these chemicals.
For eight List A chemicals (cadmium, 1,2-dichlorobenzene, 1,4-dichlorobenzene, nitrate,
nitrite, mercury, DEHP and uranium), an initial literature search was initially conducted and a
preliminary evaluation of the literature was completed. Subsequent to these literature searches
the 2015 IRIS Multi-Year Agenda announced the intention to conduct updated assessments for
the 8 chemicals (U.S. EPA, 2015). These chemicals were consequently considered as having
ongoing assessments and placed on List A.
3.2	Literature Search Process for the List B Chemicals (42)
In the case of the List B chemicals a more comprehensive evaluation was performed,
including evaluation of effects and risk-based values from published health effects or risk
assessments, and evaluation of the primary literature. The cutoff date for the initial search of the
primary literature and EPA and other health agencies assessments was December 2014. Because
some of the health assessments identified in the initial search were draft, an updated search of
EPA and other agency health was performed with a cutoff date of December 2015.
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EPA and other health agency authoritative reviews/assessments undertaken by IRIS,
OPP, ATSDR, the National Toxicology Program (NTP), National Institute of Environmental
Health Sciences (NIEHS), CalEPA, WHO, Concise International Chemical Assessment
Documents (CICADS), International Programme on Chemical Safety/Environmental Health
Criteria (IPCS/EHC), IARC, Health Canada, Joint Expert Committee on Food Additives
(JECFA), and Joint Food and Agriculture Organization of the United Nations (FAO)AVHO
Meeting on Pesticide Residues (JMPR) were included in the searches.
Literature searches were conducted to identify publications from the primary literature to
supplement the information in the authoritative reviews. The following databases were searched:
TOXLINE, MEDLINE®, Developmental and Reproductive Toxicology (DART®), Chemical
Carcinogenesis Research Information System (CCRIS), and Hazardous Substances Data Bank
(HSDB). The dates covered by the literature search were determined on an individual chemical
basis, to ensure that the literature was adequately captured, but to avoid unnecessary duplication
of work done in the authoritative reviews. In general, searches covered posting dates from 2008
(one year before the Six-Year Review 2 was finalized) through December 2014. However, if
there was a recent IRIS, OPP, OW, or ATSDR document, the searches began 2 years before
publication date of the latest toxicity assessment from IRIS/OPP/OW and 3 years before the
publication date of any ATSDR Toxicological Profile. Several chemicals which had an
assessment underway during Six-Year Review 2 and were on List A, are on List B for Six-Year
Review 3. These chemicals (listed in page 4 with asterisk), did not have supplemental searching
during Six-Year Review 3 to cover the gap in search dates during the Six-Year Review 1 to Six-
Year Review 2 interval.
The searches and screening of the literature were intended to capture the health effects
data related to (1) systemic toxicity and carcinogenicity (including MO A and genotoxicity
studies) and for (2) reproductive and developmental toxicity. The search terms were very broad,
based on the chemical name, synonyms, and CAS number. Studies with a possible impact on the
assessment (i.e., new health outcomes, different NOAEL or LOAEL, mode of action
information, etc.) were retrieved and reviewed; other studies of interest were noted based on the
information presented in the abstract. After identifying new literature and more currently
available assessments, EPA identified toxicity values for non-carcinogenic and carcinogenic
effects that could change an existing MCLG. A more current toxicological assessment from a
source other than EPA was selected when these assessments introduced new science (e.g., the
toxicity value was based on a newer principal study) or used a more current methodological
approaches (e.g., BMDL). During the Six-Year Review 3 Review, the recent non-EPA
assessments were selected for four contaminants (e.g., methoxychlor, selenium, styrene and
1,2,4-trichlorobenzene).
3.3 Screening Process for List B Chemicals
For the 42 List B chemicals which are not the subject of an ongoing assessment by U.S.
EPA, a more comprehensive evaluation was done, including evaluation of effects and risk-based
values from risk assessment sources, and evaluation of the primary literature. Literature searches
on these chemicals were conducted as discussed above in Section 3.2. Newly identified studies
that appeared relevant to the assessment of noncancer, cancer, or reproductive/developmental
effects were obtained and screened for the possible impact of new data on current assessments.
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U.S. EPA OW Drinking Water Criteria Documents serve as the basis for current
regulations (with the exception of arsenic, and radionuclides). Toxicity values from more current
assessments completed by the following U.S. EPA Offices or other organizations were evaluated
to determine if there was new information that could change the existing MCL/MCLG:
•	U.S. EPA Integrated Risk Information System (IRIS)
•	U.S. EPA Office of Pesticide Programs (OPP)
•	U.S. EPA Office of Radiation and Indoor Air (ORIA)
•	Agency for Toxic Substances and Disease Registry (ATSDR)
•	California EPA Public Health Goals (CalEPA)
•	World Health Organization (WHO)
o Drinking Water Guidelines (WHO)
o WHO's Concise International Assessment Documents (CICADs)
o International Programme on Chemical Safety - Environmental Health Criteria
Documents (IPCS, EHC)
•	Food and Agriculture Organization of the United Nations (FAO)/WHO
o Joint Meeting on Pesticide Residues (JMPR)
o Joint Expert Committee on Food Additives (JECFA)
•	Health Canada
•	National Academy of Sciences (NAS)
•	International Agency for Research on Cancer (IARC)
•	National Institute of Environmental Health Sciences (NIEHS) Report on Carcinogens
(RoC)
o National Toxicology Program (NTP)
Based on the availability of new data identified in the literature search and information
from existing assessments, recommendations were made regarding the potential for U.S. EPA
OW to update its MCLG based on the health effects data alone.
4. RESULTS
4.1 Findings for List A Chemicals with Ongoing EPA Assessments
As of December 31, 2015, 19 List A chemicals were the subject of ongoing EPA
assessments and therefore, the Agency is not recommending any changes to the MCLGs for
them at this time. The IRIS Program provides tracking information for of the chemicals for
which assessments are either underway or to be initiated. Information on the status of these
assessments can be found at the IRIS website at https://cfpub.epa.gov/ncea/iris2/atoz.cfm. Table
4 below provides the status of the 19 List A chemicals which have ongoing or planned EPA
assessments.
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Six-Year Review 3 SUMMARY HEALTH EFFECTS ASSESSMENT REPORT	December 2016
Table 4: List A Chemicals (19) with Ongoing EPA Assessments or Nominated for
Assessment
Chemical
MCLG
(mg/L)
Status
Alpha/photon emitters
0 pCi/L
EPA/ORIA is conducting a review of alpha
photon emitters
Arsenic, inorganic
0
The EPA IRIS Program is assessing
inorganic arsenic. The assessment status
can be found at:
(https ://cfbub .epa. go v/n cc a/i ri s 2/ch e m i cal L
andins ,cfm?substance nmbr=278&forceAs
scssmcntTab=true)
Atrazine
0.003
EPA is assessing atrazine and simazine
under the pesticide registration review
process.
Benzo(a)pyrene
0
The EPA IRIS Program is assessing
benzo(a)pyrene. The assessment status can
be found at:
(https ://cfbub .epa. go v/n cc a/i ri s 2/ch e m i cal L
andins ,cfm?substance nmbr= 13 6&forceAs


sessmentTab=true)
Beta/photon emitters
0
millirems
per year
EPA is conducting a review of alpha and
beta photo emitters.
Cadmium*
0.005
Cadmium is included in the EPA IRIS
Multi-Year Agenda. (U.S. EPA, 2015).
Chromium (VI) as part of
0.1
The EPA IRIS Program is assessing
total Cr)

chromium VI. The assessment status can be

found at:
(https ://cfpub .epa. go v/n cc a/i ri s 2/ch e m i cal L
andins ,cfm?substance nmbr= 144&forceAs


scssmcntTab=truc)
Di(2-ethylhexyl) phthalate
(DEHP)*
0
Di(2-ethylhexyl) phthalate is included in the
EPA IRIS Multi-Year Agenda (U.S. EPA,
2015)
Ethylbenzene
0.7
The EPA IRIS Program is assessing
ethylbenzene. The assessment status can be
found at:
(https://cfpub.cpa. sov/ncea/iris2/chemicalL
andins ,cfm?substance nmbr=51 &forceAss
essmentT ab=truc)
Glyphosate
0.7
EPA is assessing glyphosate under the
pesticide registration review process
Mercury*
0.002
Mercury is included in the EPA IRIS Multi-
Year Agenda (U.S. EPA, 2015).
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Chemical
MCLG
(mg/L)
Status
Nitrate (N)*
10
Nitrate is included in the EPA IRIS Multi-
Year Agenda (U.S. EPA, 2015)
Nitrite (N)*
1
Nitrite is included in the EPA IRIS Multi-
Year Agenda (U.S. EPA, 2015).
o-Dichlorobenzene (1,2-
Dichlorobenzene) *
0.6
1,2-Dichlorobenzene is included in the EPA
IRIS Multi-Year Agenda (U.S. EPA, 2015).
p-Dichlorobenzene (1,4-
Dichlorobenzene) *
0.075
1,4-Dichlorobenzene is included in the EPA
IRIS Multi-Year Agenda (U.S. EPA, 2015).
PCBs
0
The EPA IRIS Program is assessing PCBs.
The assessment status can be found at:
(https://cipub.epa. aov/ncea/iris2/chemicalL
andine.cfm'.'substance nmbr=294&forceAs
scssmcntTab=truc)
Radium (226, 228)
0 pCi/L
EPA/ORIA is conducting a review of
radium.
* Nominated in the IRIS Multi-Year Agenda (U.S.EPA, 2015)
4.2 Findings for List B Chemicals (42)
Based on the approach described in Sections 3.2 and 3.3 for List B chemicals, U.S. EPA
evaluated the remaining 42 contaminants to determine if there were more recent RfDs and/or
cancer risk assessments or any peer reviewed literature available that might support a change to
the MCLG.
The tables presented in the Appendix B at the end of this document provide new
assessment information on these List B chemicals. Two types of tables are available: one
summarizing EPA assessments and the other summarizing assessments from other organizations.
• For each chemical, a table was constructed that presents a "Summary of the EPA
Assessments" providing the basis for the current National Primary Drinking Water
Regulations, including RfDs and cancer groups on which the MCLGs are based, and
assessments by IRIS, OPP and/or OW (for fluoride only) that postdate the date for the
regulation. The information in these tables provides the basis for the RfDs, including
the critical effect, citation for the principal study, point of departure (whether it is a
NOAEL, LOAEL, or BMDL), and breakdown of uncertainty factors. For OPP
assessments, the Food Quality Protection Act (FQPA)4 factor is also provided, when
relevant. In addition, for cancer assessments, the year of the guidelines followed is
presented, since the approach varied with the year of the guidelines. For a number of
the chemicals evaluated between 1996 and 2001, the individual assessments provided
the assessments under both the 1986 and 1996 guidelines. In such cases, only the
4 The FQPA mandated consideration of an additional uncertainty factor to ensure protection of children for pesticide
safety evaluations.
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assessment under the 1996 guidelines is provided in the tables in the IRIS and OPP
columns. All supporting U.S. EPA documents are listed in the reference section.
• Assessments by other organizations and completed within the scope of this review
(August 2008 - December 2015) are also presented in the appendix. Where possible,
non-cancer PODs initially expressed as water concentrations were converted to a
reference dose as mg/kg/day, so that all values could be directly comparable. The
citation to WHO refers to their Drinking Water Guidelines, and if another
organization within WHO (JECFA, JMPR, CICAD, EHC) has a different value than
WHO, it is noted.
If a new assessment is available and has been selected as the basis for a potential change
in the MCLG, the information has been bolded in the table and the basis of the calculation for the
potential new MCLG is provided in a footnote.
Although the date of "verification" is well-documented for the IRIS assessments,
numerous additional revisions to the IRIS summary may be documented in the "Revision
History" for each chemical, and the "last revised" date can be several years after the verification
date, particularly for chemicals verified prior to 1996. The dates presented in Tables la through
42b for IRIS assessments refer to the verification date, as subsequent revision dates usually
reflect minor editorial changes to the IRIS file. Risk assessments conducted by IRIS can be
found at http://cfpub.epa.uov/ncea/iris/inde\.cfm?fuseaction=iris.shovvSubstanceList and those
by OPP can be found at http://iaspub.epa.gov/apex/pesticides/f?p=chemicalsearch: 1.
Additional information on the quantitative portion of the cancer assessments is presented
in these tables for the List B chemicals that have quantitative cancer slope factor assessments.
The table shows both the quantitative assessment, the methods used for modeling the data and
the process for extrapolating from the animal data to humans.
4.2.1 Findings for Consideration of a Change to the MCLG
Of the 42 List B chemicals evaluated, EPA found new information supporting potential
changes to the MCLGs for 22 chemicals; for 18 chemicals this information was from EPA
assessments. For four chemicals (methoxychlor, selenium, styrene, and 1,2,4-trichlorobenzene),
an assessment by ATSDR, Health Canada, or CalEPA was selected as the source document
suggesting that a change to the MCLGs could be considered. The information has been bolded in
the table and the basis of the calculation for the possible new MCLG is provided in a footnote.
Table 5 below provides the potential new MCLGs for the 22 chemicals along with the original
MCLG, whether the MCLG could change, and the assessment that is the basis for the potential
change. Because the MCLG for a carcinogen with a linear mode of action is zero, new data for
cancer is only considered for chemicals that are not currently regulated as carcinogens, or for
carcinogens that have new data and are now considered to have a threshold for carcinogenicity.
For twelve (12) of the 22 chemicals there is potential for the MCLG to decrease.
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Table 5: List B Chemicals with New Data and Potential New MCLG
Chemical
Original
MCLG
New
Noncancer
Dataa/Possible
Impact on
MCLG
New Cancer
Dataa/Possible
Impact on
MCLG
Potential New
MCLGb, Relevant
New Assessment
Alachlorc
0 mg/L
Yes/Yes
No/No
0.04 mg/L,
EPA OPP 2006a
Bariumc
2 mg/L
Yes/Yes
No/No
6 mg/L, EPA IRIS
2005b
Beryllium0
0.004
mg/L
Yes/Yes
No/No
0.01 mg/L,
EPA IRIS 1998c
Carbofurand
0.04
mg/L
Yes/Yes
No/No
0.0006 mg/L,
EPA OPP 2008a
Cyanide
0.2 mg/L
Yes/Yes
No/No
0.004 mg/L,
EPA IRIS 2010c
1,1 -Dichloroethylenec
0.007
mg/L
Yes/Yes
No/No
0.4 mg/L,
EPA IRIS 2002d
cis-1,2-
Dichloroethylene
0.07
mg/L
Yes/Yes
No/No
0.01 mg/L,
EPA IRIS 2010b
2,4
Dichlorophenoxy-
acetic Acid
0.07
mg/L
Yes/Yes
Yes/No
2 mg/L,
EPA OPP 2013
Diquatc
0.02
mg/L
Yes/Yes
No/No
0.04 mg/L,
EPA OPP TRED
2002e
EndothaF
0.1 mg/L
Yes/Yes
No/No
0.05 mg/L,
EPA OPP 2005d
Fluoride
4.0 mg/L
Yes/Yes
No/No
0.9-1.2 mg/L
EPA 2010a
Hexachlorocyclo-
pentadienec
0.05
mg/L
Yes/Yes
No/No
0.04 mg/L,
EPA IRIS 2001a
Lindane
0.0002
mg/L
Yes/Yes
No/No
0.03 mg/L,
EPA OPP 2002f
Methoxychlor
0.04
mg/L
Yes /Yes
No/No
0.0001 mg/L,
CalEPA 2010a
Oxamyld
0.2 mg/L
Yes/Yes
No/No
0.01 mg/L (children),
EPA OPP 2010e
Picloramc
0.5 mg/L
Yes/Yes
No/No
1 mg/L,
EPA OPP 1995b
Selenium
0.05
mg/L
Yes/Yes
No/No
0.04 mg/L,
Health Canada 2014a
Styrene
0.1 mg/L
Yes/Yes
Yes/Yes
0 mg/L,
CalEPA 2010c
Toluene0
1 mg/L
Yes/Yes
No/No
0.6 mg/L,
EPA IRIS 2005c
1,1,1-
Trichloroethane0
0.2 mg/L
Yes/Yes
No/No
14 mg/L,
EPA IRIS 2007f
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Chemical
Original
MCLG
New
Noncancer
Dataa/Possible
Impact on
MCLG
New Cancer
Dataa/Possible
Impact on
MCLG
Potential New
MCLGb, Relevant
New Assessment
1,2,4-
T richlorobenzene
0.07
mg/L
Yes/Yes
Yes/No
0.7 mg/L,
ATSDR 2010c
Xylenes0
10 mg/L
Yes/Yes
No/No
1 mg/L,
EPA IRIS 2003d
aThis column addresses whether there are new data from an updated EPA or non-EPA assessment since the latest
OW assessment that was used to support the NPDWR.
b The potential new MCLG numeric values (in mg/L) are based strictly on the health evaluation (not occurrence data
or other risk management considerations) using the RSC values currently applied to each NPDWRs except where
specifically noted.
°A potential new MCLG was evaluated during the previous Six-Year review cycles.
d Updated exposure factors for children were used to estimate the potential MCLG for carbofuran and oxamyl. The
potential new MCLGs were based on 10 kg body weight and 1L water consumption. An alternate MCLG for
children from birth to less than 12 months was also calculated based on normalized drinking water intakes per unit
body weight of 0.15L/Kg. This was determined based on the 90th percentile of drinking water consumption and the
mean body weight for age groups, birth to <1 month, 1 to <3 months, 3 to <6 months, 6 to <12 months.
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For ten of the chemicals on Table 5, the information identified in the most recent health
based risk assessment demonstrates that the current MCLG is health protective because the new
information suggests a potentially higher value. For the remaining 12, the most recent risk
assessments identify a potentially lower MCLG assuming that there would be no change in the
RSC utilized in the derivation of the original MCLG. For two of those cases,
hexachlorocyclopentadiene and selenium, the difference between the current MCLG of 0.05
mg/L and a potential revised MCLG of 0.04 mg/L would not improve the level of public health
protection given the UF applied in the derivation of the original and revised RfDs. In both cases
the critical study has not changed, the RfD differs because of changes in risk assessment
methodologies.
In the remaining cases (carbofuran, cyanide, cis dichloroethylene, endothal, fluoride,
methoxychlor, oxamyl, styrene, toluene and xylene), the data on health effects suggests a
potential to improve public health protection through a revision to the MCLG. However, as
explained above occurrence at public drinking water systems and analytical method Minimum
Reporting Levels (MRLs) must be considered when making the final determination as to whether
there is a meaningful opportunity to improve public heath through revisions to the current rule.
Additional information on fluoride health effects is provided in Appendix C.
4.2.2 Findings for No Consideration of a Change to the MCLG
No potential change to the MCLG is indicated for the remaining 20 List B chemicals
listed in Table 6 below. For these 20 chemicals, there was no new assessment supporting an
update to the MCLGs, and the literature search did not find new data that would likely affect the
MCLG.
Table 6: Chemicals with No Potential Change to the MCLG
Chemical
Original
MCLG
(mg/L)
New
Noncancer
Data/Possible
Impact on
MCLG
New Cancer
Data/Possible
Impact on
MCLG
New Data
Source
Antimony
0.006
No/No
No/No
NA
Asbestos
7 million
fibers/L
Yes/No
Yes/No
EPA IRIS 2014a
Chlordane
0
No/No
No/No
NA
Chlorobenzene
0.1
No/No
No/No
NA
Dalapon
0.2
No/No
No/No
NA
l,2-dibromo-3-
0
No/No
No/No
NA
chloroporpane
(DBCP)




trans-1,2-
0.1
Yes/No
No/No
EPA IRIS 2010b
Dichloroethylene




Di(2-ethylhexyl)
0.4
No/No
No/No
NA
adipate (DEHA)




Dinoseb
0.007
No/No
No/No
NA
Dioxin
0
Yes/No
No/No
EPA IRIS 2012b
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Endrin
0.002
No/No
No/No
NA
Ethylene dibromide
0
No/No
No/No
NA
Heptachlor
0
No/No
No/No
NA
Heptachlor epoxide
0
No/No
No/No
NA
Hexachlorobenzene
0
No/No
Yes/No
EPA OPP 2008b
Pentachlorophenol
0
Yes/No
Yes/No
EPA IRIS 2010
Thallium
0.0005
Yes/No
No/No
EPA IRIS 2009a
Toxaphene
0
No/No
No/No
NA
2,4,5-TP (Silvex)
0.05
No/No
No/No
NA
1,1,2-T richloroethane
0.003
No/No
No/No
NA
A new U.S. EPA assessment, including a new RfD, was available for pentachlorophenol
and dioxin which are carcinogens. Because the MCLG is zero for carcinogens (categories A, Bl,
or B2 under the 1986 guidelines; "carcinogenic to humans" or "likely to be carcinogenic to
humans" under the 2005 guidelines), changes to the RfD will not affect the MCLG. Therefore,
no change to the MCLG is suggested for these particular chemicals. For trans-1,2-
dichloroethylenethe the update to the original IRIS assessment did not result in a change in the
RfD that was used for MCLG derivation. For thallium, the IRIS update recommended by Six-
Year Review 1 was unable derive an RfD because of technical deficiencies in the reporting of the
original critical study and lack of better data from any of the more recent publications. The
thallium MCL is based on the analytical method PQL and therefore remains protective.
5. SUMMARY
The 1996 amendments to the Safe Drinking Water Act (SDWA) require the United States
Environmental Protection Agency (EPA) to review every six years existing NPDWRs and
determine which, if any, are candidates for revision. Under the Six-Year Review 3, the Office of
Water of U.S. EPA has completed a review of 76 water contaminants currently regulated under
the SDWA. EPA identified 12 NPDWRs ongoing, or pending regulatory actions deferred them
from a detailed health effects review at this time. Of the remaining contaminants, 19 List A
chemicals are the subject of ongoing U.S. EPA assessments or are nominated for health
assessment, thus the revision to these MCLGs is not appropriate at this time.
This assessment focused therefore on the evaluation of the 42 List B chemicals to
determine whether new information is available that could affect the MCLGs and perhaps the
MCLs. Assessments prepared by a wide range of authoritative bodies, and the published
literature was searched for new data on general toxicity, reproductive/developmental toxicity,
and carcinogenicity.
Based on this assessment, U.S. EPA identified 22 List B chemicals that had changes to
their EPA OPP or IRIS health assessments or had relevant new assessments by Health Canada,
CalEPA, or ATSDR that could potentially change the MCLGs. For the remaining 20 List B
chemicals, the Agency concluded that based on the analysis of the current information, no
change to the MCLG is indicated at this time. For twelve (12) of the 22 chemicals (in bold
below) there is potential for the MCLG to decrease. The 22 chemicals are listed below:
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Alachlor	Hexachlorocyclopentadiene
Barium	Lindane
Beryllium	Methoxychlor
Carbofuran	Oxamyl (vydate)
Cyanide, free	Picloram
2,4-D (2,4-Dichlorophenoxy Acetic Acid) Selenium
1,1-Dichloroethylene	Styrene
cis- 1,2-Dichloroethylene	Toluene
Diquat	1,2,4-Trichlorobenzene
Endothall	1,1,1-Trichloroethane
Fluoride	Xylenes
Note the chemicals above were identified based on health effects only and independent of
other considerations (e.g., analytical and occurrence data) that may influence the final selection
of contaminants recommended for revision. For additional information on other considerations in
determining if a revision is appropriate at this time, see the following support documents:
•	Analytical Feasibility Support Document for the Third Six-Year Review of
National Primary Drinking Water Regulations: Chemical Phase Rules and
Radionuclides Rules (U.S. EPA, 2016a),
•	Development of Estimated Quantitation Levels for the Third Six-Year Review of
National Primary Drinking Water Regulations (Chemical Phase Rules) (U.S.
EPA, 2016b),
•	Occurrence Analysis for Potential Source Waters for the Third Six-Year Review
of National Primary Drinking Water Regulations (U.S. EPA, 2016c), and
•	The Analysis of Regulated Contaminant Occurrence Data from Public Water
Systems in Support of the Third Six-Year Review of National Primary Drinking
Water Regulations: Chemical Phase Rules and Radionuclides Rules (U. S. EPA,
2016i).
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United States Environmental Protection Agency (U.S. EPA). 1986a. 1,1,2-Trichloroethane
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United States Environmental Protection Agency (U.S. EPA). 1986g. Fluorine (soluble fluoride
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date February 26, 1985. U.S. Environmental Protection Agency, Office of Research and
Development, Washington, DC.
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United States Environmental Protection Agency (U.S. EPA). 1986i. Guidelines for Carcinogen
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United States Environmental Protection Agency (U.S. EPA). 19861. Nitrite (CASRN 14797-65-
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22-0). Integrated Risk Information System. Oral RfD Assessment, verification date December 9,
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Trichlorophenoxy)propionic acid (2,4,5-TP) (CASRN 93-72-1). Integrated Risk Information
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Protection Agency, Office of Research and Development, Washington, DC.
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21-4). Integrated Risk Information System. Carcinogenicity assessment, verification date
December 2, 1987. U.S. Environmental Protection Agency, Office of Research and
Development, Washington, DC.
http://cfpub.epa.gov/ncea/iris/iris docum ent s/docum ent s/sub st/03 71 summary.pdf
United States Environmental Protection Agency (U.S. EPA). 1987c. Carbofuran (CASRN 1563-
66-2). Integrated Risk Information System. Oral RfD Assessment, verification date March 18,
1987.	U.S. Environmental Protection Agency, Office of Research and Development,
Washington, DC.
http://cfpub.epa.gov/ncea/iris/iris documents/documents/subst/0218 summary.pdf
United States Environmental Protection Agency (U.S. EPA). 1987d. Di(2-ethylhexyl)phthalate
(CASRN 117-81-7). Integrated Risk Information System. Carcinogenicity assessment,
verification date October 7, 1987. U.S. Environmental Protection Agency, Office of Research
and Development, Washington, DC.
http://cfpub.epa.gov/ncea/iris/iris documents/documents/subst/OO 14 summary.pdf
United States Environmental Protection Agency (U.S. EPA). 1987e. Picloram (CASRN 1918-02-
1).	Integrated Risk Information System. Oral RfD assessment, verification date April 15, 1987.
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U.S. Environmental Protection Agency, Office of Research and Development, Washington, DC.
http://cfpub.epa.gov/ncea/iris/iris documents/documents/subst/0256 sumtnarv.pdf
United States Environmental Protection Agency (U.S. EPA). 1987f. Heptachlor (CASRN 76-44-
8). Integrated Risk Information System. Oral RfD assessment, verification date April 16, 1987
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Agency, Office of Research and Development, Washington, DC.
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United States Environmental Protection Agency (U.S. EPA). 1987h. Methoxychlor (CASRN 72-
43-5). Integrated Risk Information System. Carcinogenicity assessment, verification date
October 7, 1987. U.S. Environmental Protection Agency, Office of Research and Development,
Washington, DC.
http://cfpub.epa.gov/ncea/iris/iris docum ent s/docum ent s/ sub st/0369 summarv.pdf
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United States Environmental Protection Agency (U.S. EPA). 1987j. Peer Review Workshop on
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35-2). Integrated Risk Information System. Carcinogenicity assessment, verification date March
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Washington, DC.
http://cfpub.epa.gov/ncea/iris/iris docum ent s/docum ent s/ sub st/0346 summarv.pdf
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May 26, 1988. U.S. Environmental Protection Agency, Office of Research and Development,
Washington, DC.
http://cfpub.epa.gov/ncea/iris/iris documents/documents/subst/0198 summarv.pdf
United States Environmental Protection Agency (U.S. EPA). 1988b. 1,2,4-Trichlrobenzene
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verification date October 19, 1988. U.S. Environmental Protection Agency, Office of Research
and Development, Washington, DC.
https://cfpub.epa.gov/ncea/iris/iris documents/documents/subst/01 19 summarv.pdf
United States Environmental Protection Agency (U.S. EPA). 1988c. 2-(2,4,5-
Trichlorophenoxy)propionic acid (2,4,5-TP) (CASRN 93-72-1). Integrated Risk Information
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System. Oral RfD Assessment, verification date January 21, 1988. U.S. Environmental
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http://cfpub.epa.gov/ncea/iris/iris documents/documents/subst/0323 summarv.pdf
United States Environmental Protection Agency (U.S. EPA). 1988d. Cadmium (CASRN 7440-
43-9). Integrated Risk Information System. Oral RfD Assessment, verification date May 25,
1988. U.S. Environmental Protection Agency, Office of Research and Development,
Washington, DC.
http://cfpub.epa.gov/ncea/iris/iris documents/documents/subst/0141 summarv.pdf
United States Environmental Protection Agency (U.S. EPA). 1988e. Dalapon (CASRN 75-99-0).
Integrated Risk Information System. Oral RfD Assessment, verification date June 22, 1988. U.S.
Environmental Protection Agency, Office of Research and Development, Washington, DC.
http://cfpub.epa.gov/ncea/iris/iris documents/documents/subst/0146 summarv.pdf
United States Environmental Protection Agency (U.S. EPA). 1988f. Drinking Water Criteria
Document for 2,3,7,8-Tetrachl orodibenzo-/>di oxi n, Final draft. Office of Drinking Water:
Washington, DC. PB90-215294.
United States Environmental Protection Agency (U.S. EPA). 1988g. Endrin (CASRN 72-20-8).
Integrated Risk Information System. Oral RfD assessment, verification date April 20, 1988 and
carcinogenicity assessment, verification date October 19, 1988. U.S. Environmental Protection
Agency, Office of Research and Development, Washington, DC.
http://cfpub.epa.gov/ncea/iris/iris docum ents/docum ent s/ sub st/03 63 summarv.pdf
United States Environmental Protection Agency (U.S. EPA). 1988h. Hexachlorobenzene
(CASRN 118-74-1). Integrated Risk Information System. Oral RfD Assessment, verification
date May 26, 1988. U.S. Environmental Protection Agency, Office of Research and
Development, Washington, DC.
http://cfpub.epa.gov/ncea/iris/iris docum ents/docum ent s/ sub st/03 74 summarv.pdf
United States Environmental Protection Agency (U.S. EPA). 1988i. Mercuric Chloride (HgCh)
(CASRN 7487-94-7). Integrated Risk Information System. Oral RfD Assessment, verification
date November 16, 1988. U.S. Environmental Protection Agency, Office of Research and
Development, Washington, DC.
http://cfpub.epa.gov/ncea/iris/iris documents/documents/subst/0692 summarv.pdf
United States Environmental Protection Agency (U.S. EPA). 1989a. 1,2-Dichlorobenzene
(CASRN 95-50-1). Integrated Risk Information System. Oral RfD assessment, verification date
February 16, 1989 and carcinogenicity assessment, verification date December 6, 1989. U.S.
Environmental Protection Agency, Office of Research and Development, Washington, DC.
http://cfpub.epa.gov/ncea/iris/iris documents/documents/subst/0408 summarv.pdf
United States Environmental Protection Agency (U.S. EPA). 1989b. Chlorobenzene (CASRN
108-90-7). Integrated Risk Information System. Oral RfD assessment, verification date January
19, 1989. U.S. Environmental Protection Agency, Office of Research and Development,
Washington, DC.
http://cfpub.epa.gov/ncea/iris/iris docum ents/docum ent s/ sub st/0399 summarv.pdf
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United States Environmental Protection Agency (U.S. EPA). 1989c. Dinoseb (CASRN 88-85-7).
Integrated Risk Information System. Carcinogenicity assessment, verification date May 3, 1989.
U.S. Environmental Protection Agency, Office of Research and Development, Washington, DC.
http://cfpub.epa.gov/ncea/iris/iris documents/documents/subst/0047 summary.pdf
United States Environmental Protection Agency (U.S. EPA). 1989d. Hexachlorobenzene
(CASRN 118-74-1). Integrated Risk Information System. Carcinogenicity assessment,
verification date March 1, 1989. U.S. Environmental Protection Agency, Office of Research and
Development, Washington, DC.
http://cfpub.epa.gov/ncea/iris/iris docum ent s/docum ent s/ sub st/03 74 summary.pdf
United States Environmental Protection Agency (U.S. EPA). 1989e. Uranium, Soluble Salts (no
CASRN). Integrated Risk Information System. Oral RfD Assessment, verification date January
19, 1989. U.S. Environmental Protection Agency, Office of Research and Development,
Washington, DC.
http://cfpub.epa.gov/ncea/iris/iris documents/documents/subst/0421 summary.pdf
United States Environmental Protection Agency (U.S. EPA). 1990a. Chlorobenzene (CASRN
108-90-7). Integrated Risk Information System. Carcinogenicity assessment, verification date
April 4, 1990. U.S. Environmental Protection Agency, Office of Research and Development,
Washington, DC.
http://cfpub.epa.gov/ncea/iris/iris docum ent s/docum ent s/ sub st/0399 summary.pdf
United States Environmental Protection Agency (U.S. EPA). 1990b. Methoxychlor (CASRN 72-
43-5). Integrated Risk Information System. Oral RfD assessment, verification date June 21,
1990. U.S. Environmental Protection Agency, Office of Research and Development,
Washington, DC.
http://cfpub.epa.gov/ncea/iris/iris docum ent s/docum ent s/ sub st/0369 summary.pdf
United States Environmental Protection Agency (U.S. EPA). 1990c. Nitrate (CASRN 14797-55-
8). Integrated Risk Information System. RfD assessment, verification date August 22, 1990. U.S.
Environmental Protection Agency, Office of Research and Development, Washington, DC.
http://cfpub.epa.gov/ncea/iris/iris docum ent s/docum ent s/ sub st/0076 summary.pdf
United States Environmental Protection Agency (U.S. EPA). 1990d. Selenium (CASRN 7782-
49-2). Integrated Risk Information System. Carcinogenicity Assessment, verification date March
7, 1990. U.S. Environmental Protection Agency, Office of Research and Development,
Washington, DC.
http://cfpub.epa.gov/ncea/iris/iris docum ents/docum ent s/ sub st/0472 summary.pdf
United States Environmental Protection Agency (U.S. EPA). 1991a. 1,2,4-Trichlorobenzene
(CASRN 120-82-1). Integrated Risk Information System. Oral RfD assessment, verification date
December 12, 1991. U.S. Environmental Protection Agency, Office of Research and
Development, Washington, DC.
http://cfpub.epa.gov/ncea/iris/iris documents/documents/subst/01 19 summary.pdf
United States Environmental Protection Agency (U.S. EPA). 1991b. Alachlor (CASRN 15972-
60-8). Integrated Risk Information System. Oral RfD assessment, verification date March 27,
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1991. U.S. Environmental Protection Agency, Office of Research and Development,
Washington, DC.
http://cfpub.epa.gov/ncea/iris/iris documents/documents/subst/0129 sumtnarv.pdf
United States Environmental Protection Agency (U.S. EPA). 1991c. Di(2-ethylhexyl)adipate
(CASRN 103-23-1). Integrated Risk Information System. Oral RfD assessment, verification date
July 16, 1991 and carcinogenicity assessment, verification date April 4, 1991. U.S.
Environmental Protection Agency, Office of Research and Development, Washington, DC.
http://cfpub.epa.gov/ncea/iris/iris documents/documents/subst/0420 summary.pdf
United States Environmental Protection Agency (U.S. EPA). 199Id. Drinking Water Criteria
Document for Phthalic Acid Esters (PAES). Final draft. Office of Drinking Water: Washington,
DC. PB92- 173442.
United States Environmental Protection Agency (U.S. EPA). 1991e. National Primary Drinking
Water Regulations: Monitoring for Volatile Organic Chemicals; MCLGs and MCLs for
Aldicarb, Aldicarb Sulfoxide, Aldicarb Sulfone, Pentachlorophenol, and Barium. Final Rule.
Federal Register 56(126): 30266.
United States Environmental Protection Agency (U.S. EPA). 199If. National Primary Drinking
Water Regulations: Special Regulations, Including Monitoring Regulations and Prohibition on
Lead Use, Prohibition on Use of Lead Pipes, Solder and Flux. Federal Register 40(141).
Available at: http://www.ecfr.gov/cgi-bin/text
idx?c=ecfr&sid=dd3925a2e804f53ebe02802elade5979&rgn=div8&view=text&node=40:23.0.1.
1.3.5.16.4&idno=40
United States Environmental Protection Agency (U.S. EPA). 1991g. National Primary Drinking
Water Regulations: Synthetic Organic Chemicals and Inorganic Chemicals; Monitoring for
Unregulated Contaminants; National Primary Drinking Water Regulations Implementation;
National Secondary Drinking Water Regulations. Final Rule. Federal Register 56(20): 3526-
3597.
United States Environmental Protection Agency (U.S. EPA). 1991h. Selenium (CASRN 7782-
49-2). Integrated Risk Information System. Oral RfD Assessment, verification date March 27,
1991. U.S. Environmental Protection Agency, Office of Research and Development,
Washington, DC.
http://cfpub.epa.gov/ncea/iris/iris docum ent s/docum ent s/ sub st/0472 summary.pdf
United States Environmental Protection Agency (U.S. EPA). 1992a. Drinking Water Criteria
Document for Endrin. Final draft. Office of Drinking Water: Washington, D.C. ECAO-CIN-423.
United States Environmental Protection Agency (U.S. EPA). 1992b. National Primary Drinking
Water Regulations: Synthetic Organic Chemicals and Inorganic Chemicals; National Primary
Drinking Water Regulation Implementation. Final rule. Federal Register 57(138): 31776-31849.
United States Environmental Protection Agency (U.S. EPA). 1992c. Reregi strati on Eligibility
Document Heptachlor, List A, Case 0175. Office of Pesticide Programs: Washington, DC.
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http://www3.epa.gov/pesticides/chem search/reg actions/reregistration/red PC-044801 1-Mar-
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United States Environmental Protection Agency (U.S. EPA). 1994a. Mercuric Chloride (HgCh)
(CASRN 7487-94-7). Integrated Risk Information System. Carcinogenicity Assessment,
verification date March 3, 1994. U.S. Environmental Protection Agency, Office of Research and
Development, Washington, DC.
http://cfpub.epa.gov/ncea/iris/iris documents/documents/subst/0692 summarv.pdf
United States Environmental Protection Agency (U.S. EPA). 1994b Mercury, Elemental
(CASRN 7439-97-6). Integrated Risk Information System. Carcinogenicity Assessment,
verification date March 3, 1994. U.S. Environmental Protection Agency, Office of Research and
Development, Washington, DC.
http://cfpub.epa.gov/ncea/iris/iris documents/documents/subst/0370 summarv.pdf
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Inhalation Reference Concentrations and Application of Inhalation Dosimetry. Environmental
Criteria and Assessment Office, Office of Health and Environmental Assessment, Office of
Research and Development: Research Triangle Park, NC. EPA/600/8-90/066F. Available at:
http://ofmpub.epa.gov/eims/eimscomm.getfile7p download id=473048
United States Environmental Protection Agency (U.S. EPA). 1994d. Methylmercury (MeHg)
(CASRN 22967-92-6). Integrated Risk Information System. Carcinogenicity Assessment,
verification date March 3, 1994. U.S. Environmental Protection Agency, Office of Research and
Development, Washington, DC.
http://cfpub.epa.gov/ncea/iris/iris docum ent s/docum ent s/ sub st/0073 summarv.pdf
United States Environmental Protection Agency (U.S. EPA). 1995a. Reregi strati on Eligibility
Decision (RED) for Diquat Dibromide. Office of Prevention, Pesticides and Toxic Substances:
Washington, DC. http://archive.epa.gov/pesticides/reregistration/web/pdf/0288.pdf
United States Environmental Protection Agency (U.S. EPA). 1995b. Reregi strati on Eligibility
Decision (RED) for Picloram. Office of Prevention, Pesticides and Toxic Substances:
Washington, DC. EPA738-R95-019.
http://archive.epa.gov/pesticides/reregistration/web/pdf/0096.pdf
United States Environmental Protection Agency (U.S. EPA). 1996. Proposed Guidelines for
Carcinogen Risk Assessment. Federal Register 61(79): 17960-18011. EPA/600/P-92/003C.
http://nepis.epa.gov/E\e/ZvPDF.cgi/3000261 D.PDF?Dockev=3000261 D.PDF
United States Environmental Protection Agency (U.S. EPA). 1997. Chlordane (Technical)
(CASRN 12789-03-6). Integrated Risk Information System. Oral RfD assessment, consensus
date November 3, 1997 and carcinogenicity assessment, consensus date November 3, 1997. U.S.
Environmental Protection Agency, Office of Research and Development, Washington, DC.
http://cfpub.epa.gov/ncea/iris/iris documents/documents/subst/0142 summarv.pdf
United States Environmental Protection Agency (U.S. EPA). 1998a. Barium and Compounds
(CASRN 7440-39-3). Integrated Risk Information System. Carcinogenicity assessment,
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December 2016
consensus date February 18, 1998. U.S. Environmental Protection Agency, Office of Research
and Development, Washington, DC.
http://cfpub.epa.gov/ncea/iris/iris documents/documents/subst/OO 10 sumtnarv.pdf
United States Environmental Protection Agency (U.S. EPA). 1998b. Integrated Risk Information
System (IRIS): Toxicological Review of Barium Compounds in Support of Summary. National
Center for Environmental Assessment, Office of Research and Development: Washington, DC.
http://cfpub.epa.gov/ncea/iris/iris documents/documents/toxrevievvs/OO 1 Otr.pdf
United States Environmental Protection Agency (U.S. EPA). 1998c. Integrated Risk Information
System (IRIS): Toxicological Review of Beryllium and Compounds in Support of Summary
Information. Noncancer Assessment. National Center for Environmental Assessment, Office of
Research and Development, Washington, DC.
http://cfpub.epa.gov/ncea/iris/iris documents/documents/toxreviews/OO 12tr.pdf
United States Environmental Protection Agency (U.S. EPA). 1998d. Reregi strati on Eligibility
Decision (RED) for Alachlor. Office of Prevention, Pesticides and Toxic Substances,
Washington DC. EPA 738-R-98-020.
http://archive.epa.gov/pesticides/reregistration/web/pdf/0063.pdf
United States Environmental Protection Agency (U.S. EPA). 1999. Guidelines for Carcinogen
Risk Assessment. Review Draft. NCEA-F-0644. U.S. Environmental Protection Agency,
Washington, DC. http://ofmpub.epa.gov/eims/eimscomm.getfile7p download id=437005
United States Environmental Protection Agency (U.S. EPA). 2000a. Recommended guidance for
review of existing national primary drinking water regulations, The National Drinking Water
Advisory Council (NDWAC) Recommendations. November 2000. Available on the internet at:
https://www.regulations.gov/document?D=EPA-HQ-OW-2002-0012-0021
United States Environmental Protection Agency (U.S. EPA). 2000b. Methodology for Deriving
Ambient Water Quality Criteria for the Protection of Human Health. Final draft. Office of Water:
Washington, DC. https://nepis.epa. gov/Exe/ZvPUR.L.cgi?Dockev=20003 D2R.txt
United States Environmental Protection Agency (U.S. EPA). 2000c. National Primary Drinking
Water Regulations: Radionuclides. Final Rule. Federal Register 65(236): 76708.
United States Environmental Protection Agency (U.S. EPA). 2000d. Benchmark Dose Technical
Guidance Document. External review draft. Risk Assessment Forum, U.S. Environmental
Protection Agency: Washington, DC. Available at:
https://cfpub.epa.gov/ncea/risk/recordisplav.cfm?deid=20871
United States Environmental Protection Agency (U.S. EPA). 2001a. Hexachlorocyclopentadiene
(CASRN 77-47-4). Integrated Risk Information System. Oral RfD assessment, consensus date
June 19, 2001 and carcinogenicity assessment, consensus date June 19, 2001. U.S.
Environmental Protection Agency, Office of Research and Development, Washington, DC.
http://cfpub.epa.gov/ncea/iris/iris documents/documents/subst/0059 sunnnary.pdf
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Six-Year Review 3
SUMMARY HEALTH EFFECTS ASSESSMENT REPORT
December 2016
United States Environmental Protection Agency (U.S. EPA). 2001b. Implementation of the
Determinations of a Common Mechanism of Toxicity for N-methyl Carbamate Pesticides and for
Certain Chloroacetanilide Pesticides. Office of Pesticide Programs: Washington, DC.
http://www.regi ' , - '¦ umentDeta	r ,
United States Environmental Protection Agency (U.S. EPA). 2002a. Protocol for the Review of
Existing National Primary Drinking Water Regulations. Draft. Office of Drinking Water:
Washington, DC. 815-D-02-004. Available at:
http://nepis.epa.gov/Exe/ZyPDF.cgi/20001 WPC.PDF?Dockey=20001 WPC.PDF
United States Environmental Protection Agency (U.S. EPA). 2002b. National Primary Drinking
Water Regulations: Announcement of the Results of EPA's Review of Existing Drinking Water
Standards and Request for Public Comment. Federal Register 67(74): 19029-19090.
https://www.gpo.gov/fdsvs/pkg/FR-2002-04-17/html/Q2-9154.htm
U.S. Environmental Protection Agency U.S. EPA, 2002c. A review of the reference dose and
reference concentration process. Risk Assessment Forum, Washington, DC. EPA/630/P-
02/002F. https://vvvvvv.epa.gov/sites/production/files/2014-12/documents/rfd-final.pdf
United States Environmental Protection Agency (U.S. EPA). 2002d. Integrated Risk Information
System (IRIS): Toxicological Review of 1,1-Dichloroethylene in Support of Summary
Information. National Center for Environmental Assessment, Office of Research and
Development: Washington, DC.
http://cfpub.epa.gov/ncea/iris/iris documents/documents/toxreviews/0039tr.pdf
United States Environmental Protection Agency (U.S. EPA). 2002e. Diquat Dibromide HED
Risk Assessment for Tolerance Reassessment Eligibility Document (TRED.) PC Code No:
032201; DP Barcode: D281890; Submission Barcode: S611057.
http://vvvvvv. regulations, gov/#! docuinentDetail;D=EPA-HO-OPP-2009-0920-00Q7
United States Environmental Protection Agency (U.S. EPA). 2002f. Reregi strati on Eligibility
Decision (RED) for Lindane. Office of Prevention, Pesticides and Toxic Substances:
Washington, DC. http://vvvvvv.regulations.gov/#!docuinentDetail;D=EPA-HQ-OPP-2002-02Q2-
0027
United States Environmental Protection Agency (U.S. EPA). 2003a. Announcement of
Completion of EPA's Review of Existing Drinking Water Standards. Federal Register 68(138):
42908. Available at: _https://www.epa.gov/dwsixyearreview/six-year-review-l-drinking-water-
standards#frn
United States Environmental Protection Agency (U.S. EPA). 2003d. Integrated Risk Information
System (IRIS): Toxicological Review of Xylenes in Support of Summary Information. National
Center for Environmental Assessment, Office of Research and Development: Washington, DC.
http://cfpub.epa.gov/ncea/iris/iris documents/documents/toxreviews/0270tr.pdf
United States Environmental Protection Agency (U.S. EPA). 2003e. Protocol for the Review of
Existing National Primary Drinking Water Regulations. Final. Office of Water: Washington, DC.
Available at: http://vvvvvv.epa.gov/sites/production/files/2014-12/documents/815r03002.pdf
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December 2016
United States Environmental Protection Agency (U.S. EPA). 2003f. Six-Year Review: Chemical
Contaminants; Health Effects Technical Support Document. Final. Office of Water: Washington,
DC. EPA 822-R-03-008.
United States Environmental Protection Agency (U.S. EPA). 2004. Integrated Risk Information
System (IRIS): Toxicological Review of 1,2-Dibromoethane in Support of Summary
Information. National Center for Environmental Assessment, Office of Research and
Development: Washington, DC.
http://cfpub.epa.gov/ncea/iris/iris documents/documents/toxrevievvs/0361 tr.pdf
United States Environmental Protection Agency (U.S. EPA). 2005a. Guidelines for Carcinogen
Risk Assessment. Risk Assessment Forum, U.S. Environmental Protection Agency: Washington,
DC. EPA/630/P-03/001B. http://www3.epa.gov/airtoxics/cancer guidelines final 3-25-05.pdf
United States Environmental Protection Agency (U.S. EPA). 2005b. Integrated Risk Information
System (IRIS): Toxicological Review of Barium and Compounds. Noncancer Assessment.
National Center for Environmental Assessment, Office of Research and Development:
Washington, DC.
http://cfpub.epa.gov/ncea/iris/iris docuinents/docuinents/toxreviews/OO 1 Otr.pdf
United States Environmental Protection Agency (U.S. EPA). 2005c. Integrated Risk Information
System (IRIS): Toxicological Review of Toluene in Support of Summary Information. National
Center for Environmental Assessment, Office of Research and Development: Washington, DC.
http://cfpub.epa.gov/ncea/iris/iris docuinents/docuinents/toxreviews/O1 18tr.pdf
United States Environmental Protection Agency (U.S. EPA). 2005d. Reregi strati on Eligibility
Decision for Endothall. EPA 738-R-05-008, Case #: 2245. Office of Prevention, Pesticides, and
Toxic Substances: Washington, DC.
http://archive.epa.gov/pesticides/reregistration/vveb/pdf/endothall red.pdf
United States Environmental Protection Agency (U.S. EPA). 2005e. Supplemental Guidance for
Assessing Susceptibility from Early-life Exposure to Carcinogens. Risk Assessment Forum, U.S.
Environmental Protection Agency: Washington, DC. EPA/630/R-03/003F. Available at:
https://www3.epa.gov/airtoxics/childrens supplement final.pdf
United States Environmental Protection Agency (U.S. EPA). 2006a. Acetochlor/Alachlor:
Cumulative Risk Assessment for the Chloroacetanilides. Office of Prevention, Pesticides and
Toxic Substances: Washington, DC.
United States Environmental Protection Agency (U.S. EPA). 2006b. Report of the Food Quality
Protection Act (FQPA) Tolerance Reassessment and Risk Management Decision (TRED) for
Sodium Cyanide. Office of Pesticide Programs: Washington, DC.
https://www.regulations.gOv/#! documentDetail;D=EPA-HQ-OPP-2006-0352-0004
United States Environmental Protection Agency (U.S. EPA). 2007a. National Primary Drinking
Water Regulations for Lead and Copper: Short-Term Regulatory Revisions and Clarifications.
Federal Register 72(57782): 57782-57820. Available at:
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Six-Year Review 3 SUMMARY HEALTH EFFECTS ASSESSMENT REPORT	December 2016
https://www.federalregister.gov/articles/2007/10/10/E7-19432/national-primarv-drinking-water-
regulations-for-lead-and-copper-short-term-regulatory-revisions-and
United States Environmental Protection Agency (U.S. EPA). 2007b. Gross Alpha Health Review
Summary, in Support of the Six Year II Review. Office of Radiation and Indoor Air:
Washington, DC.
United States Environmental Protection Agency (U.S. EPA). 2007c. Beta/Photon Health Review
Summary, in Support of the Six Year II Review. Office of Radiation and Indoor Air:
Washington, DC.
United States Environmental Protection Agency (U.S. EPA). 2007d. Radium Health Review
Summary, in Support of the Six Year II Review. Office of Radiation and Indoor Air:
Washington, DC.
United States Environmental Protection Agency (U.S. EPA). 2007e.
ACETOCHLOR/ALACHLOR: Revised Cumulative Risk Assessment for the Chloroacetanilides
to Support the Proposed New Uses on Alachlor and Acetochlor. PP#8F05000 and 8F5025
(Alachlor), PP#6F4791, 1F6263 and 5F6918 (Acetochlor). PC Codes: 121601 & 090501. DP
Barcode D336214. http://www.regulations.gov/#!documentDetail;D=EPA-HQ-OPP-2009-0002-
0008
United States Environmental Protection Agency (U.S. EPA). 2007f. Integrated Risk Information
System (IRIS): Toxicological Review of 1,1,1-Trichloroethane. National Center for
Environmental Assessment, Office of Research and Development: Washington, DC.
http://cfpub.epa.gov/ncea/iris/iris documents/documents/toxreviews/O197tr.pdf
United States Environmental Protection Agency (U.S. EPA). 2008a. HED Revised Risk
Assessment for the Notice of Intent to Cancel (NOIC). PC 090601. DP# 347038.
http://www.regulations.gov/#!documentDetail;D=EPA-HQ-QPP-2007-1088-0034
United States Environmental Protection Agency (U.S. EPA). 2008b. Reregi strati on Eligibility
Decision for Pentachlorophenol. Office of Prevention, Pesticides and Toxic Substances:
Washington, DC.
http://www3.epa.gov/pesticides/chem search/reg actions/reregistration/red PC-063001 25-Sep-
08.pdf
United States Environmental Protection Agency (U.S. EPA). 2008c. Revised Registration
Eligibility Decision for para-dichlorobenzene. Office of Prevention, Pesticides and Toxic
Substances: Washington, DC. http://archive.epa.gov/pesticides/reregistration/vveb/pdf/para-
di chl orob enzene-red-revi sed.pdf
United States Environmental Protection Agency (U.S. EPA). 2009a. Integrated Risk Information
System (IRIS): Toxicological Review of Thallium and Compounds in Support of Summary
Information. National Center for Environmental Assessment, Office of Research and
Development: Washington, DC.
http://cfpub.epa.gov/ncea/iris/iris documents/documents/toxrevievvs/1012tr.pdf
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December 2016
United States Environmental Protection Agency (U.S. EPA). 2009b. Provisional Peer-Reviewed
Toxicity Values for 1,2,4-Trichlorobenzene (CASRN 120-82-1). U.S. Environmental Protection
Agency, Office of Research and Development, Cincinnati, OH.
http://hhpprtv.ornl.gov/issue papers/Trichlorobenzene 124.pdf
United States Environmental Protection Agency (U.S. EPA). 2009c. Six-Year Review 2 Health
Effects Assessment: Summary Report. Office of Water: Washington, DC. Available at:
http://www.epa.gov/sites/production/files/2014-12/documents/822r090Q6.pdf
United States Environmental Protection Agency (U.S. EPA). 2010a. Fluoride: Dose-Response
Analysis for Non-Cancer Effects. Health and Ecological Criteria Division, Office of Water:
Washington, DC. Available at: http://nepis.epa.gov/Exe/ZyPURL.cgi?Dockev=P100N4S8.txt
United States Environmental Protection Agency (U.S. EPA). 2010b. Integrated Risk Information
System (IRIS): Toxicological Review of cis-1,2-Dichloroethylene and trans-1,2-
Dichloroethylene: in Support of Summary Information on the Integrated Risk Information
System (IRIS). National Center for Environmental Assessment, Office of Research and
Development: Washington, DC.
http://cfpub.epa.gov/ncea/iris/iris documents/documents/toxrevievvs/0418tr.pdf
United States Environmental Protection Agency (U.S. EPA). 2010c. Integrated Risk Information
System (IRIS): Toxicological Review of Hydrogen Cyanide and Cyanide Salts in Support of
Summary Information. National Center for Environmental Assessment, Office of Research and
Development: Washington, DC.
http://cfpub.epa.gov/ncea/iris/iris documents/documents/toxreviews/0060tr.pdf
United States Environmental Protection Agency (U.S. EPA). 2010d. Integrated Risk Information
System (IRIS): Toxicological Review of Pentachlorophenol in Support of Summary Information.
National Center for Environmental Assessment, Office of Research and Development:
Washington, DC.
http://cfpub.epa.gov/ncea/iris/iris documents/documents/toxreviews/0086tr.pdf
United States Environmental Protection Agency (U.S. EPA). 2010e. Memorandum: Updated
toxicity endpoints for oxamyl. Office of Chemical Safety and Pollution Prevention, Washington,
DC. http://www.regulations.gov/#!documentDetail;D=EPA-HQ-QPP-2010-0028-0011
United States Environmental Protection Agency (U.S. EPA). 201 Of. National Primary Drinking
Water Regulations; Announcement of the Results of EPA's Review of Existing Drinking Water
Standards and Request for Public Comment and/or Information on Related Issues; Notice.
Federal Register Volume 75, Number 59. Available at: https://www.gpo.gov/fdsys/pkg/FR-2010-
03-29/html/2010-6624.htm
United States Environmental Protection Agency (U.S. EPA). 201 la. Exposure Factors
Handbook: 2011 Edition. EPA/600/R-090/052F, Office of Research and Development,
Washington, DC. Available at: http://cfpub.epa.gov/ncea/risk/recordisplay.cfm?deid=236252
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December 2016
United States Environmental Protection Agency (U.S. EPA). 201 lb. National Primary Drinking
Water Regulations: Group Regulation of Carcinogenic Volatile Organic Compounds (VOCs). 40
CFR 141 40 CFR 142. Available at: https://vosemite.epa.gov/opei/rulegate.nsf/bvRIN/2040-
AF29
United States Environmental Protection Agency (U.S. EPA). 2012a. Benchmark Dose Technical
Guidance Document. Risk Assessment Forum, U.S. Environmental Protection Agency:
Washington, DC. Available at: http://wvvvv2.epa.gov/sites/production/files/2015-
01 /documents/benchmark dose guidance.pdf
United States Environmental Protection Agency (U.S. EPA). 2012b. 2,3,7,8-Tetrachlorodibenzo-
p-dioxin (TCDD) (CASRN 1746-01-6). Integrated Risk Information System (IRIS). Oral RfD
assessment, verification date February 17, 2012, Office of Research and Development:
Washington, DC. Available at: https://cfpub.epa.gov/ncea/iris/iris documents/documents/subst
/1024 sumrnary.pdf
United States Environmental Protection Agency (U.S. EPA). 2013. Human Health Risk
Assessment for a Proposed Use of 2,4-D Choline on Herbicide-Tolerant Corn and Soybean.
Office of Chemical Safety and Pollution Prevention.
http://www.regulations.gov/#!docuinentDetail;D=EPA-HO-OPP-2014-0195-0007
United States Environmental Protection Agency (U.S. EPA). 2014a. Integrated Risk Information
System (IRIS). Toxicological Review of Libby Amphibole Asbestos in Support of Summary
Information. National Center for Environmental Assessment, Office of Research and
Development: Washington, DC. December 2014.
http://cfpub.epa.gov/ncea/iris/iris documents/documents/toxrevievvs/1026tr.pdf
United States Environmental Protection Agency (U.S. EPA). 2014b. National Drinking Water
Advisory Council Meeting Summary, November 6-7, 2014.
http://www.epa.gov/sites/production/files/2015-10/documents/lndwacmeetingsumll62014.pdf
United States Environmental Protection Agency (U.S. EPA). 2015. IRIS Agenda.
https://vvvvvv.epa.gov/iris/iris-agenda
United States Environmental Protection Agency (U.S. EPA). 2016a. Analytical Feasibility
Support Document for the Third Six-Year Review of National Primary Drinking Water
Regulations: Chemical Phase Rules and Radionuclides Rules.
United States Environmental Protection Agency (U.S. EPA). 2016b. Development of Estimated
Quantitation Levels for the Third Six-Year Review of National Primary Drinking Water
Regulations (Chemical Phase Rules).
United States Environmental Protection Agency (U.S. EPA). 2016c. Occurrence Analysis for
Potential Source Waters for the Third Six-Year Review of National Primary Drinking Water
Regulations.
United States Environmental Protection Agency (U.S. EPA). 2016d. Protocol for Six-Year
Review 3 of National Primary Drinking Water Regulations.
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United States Environmental Protection Agency (U.S. EPA). 2016e. Support Document for
Third Six Year Review of Drinking Water Regulations for Acrylamide and Epichlorohydrin.
United States Environmental Protection Agency (U.S. EPA). 2016f. Technical Support
Document for Microbial Contaminant Regulations Under Six-Year Review 3.
United States Environmental Protection Agency (U.S. EPA). 2016g. Technical Support
Document for Long-Term 2 Regulation Under Six-Year Review 3.
United States Environmental Protection Agency (U.S. EPA). 2016h. Technical Support
Document for Disinfectants/Disinfection Byproducts Regulations Under Six-Year Review 3.
United States Environmental Protection Agency (U.S. EPA). 2016i. The Analysis of Regulated
Contaminant Occurrence Data from Public Water Systems in Support of the Third Six-Year
Review of National Primary Drinking Water Regulations: Chemical Phase Rules and
Radionuclides Rules.
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contaminated water. Am. J. Public Health. 41(8 Pt 1): 986-996.
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December 2016
World Health Organization (WHO). 201 lc. Selenium in Drinking-water: Background Document
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Washington D.C. 20460.
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APPENDIX A -LIST A TOXICITY TABLES FOR SELECTED CHEMICALS
INCLUDED IN IRIS MULTI-YEAR AGENDA
For eight List A chemicals (cadmium, 1,2-dichlorobenzene, 1,4-dichlorobenzene, nitrate,
nitrite, mercury, DEHP and uranium), an initial literature search was conducted and a
preliminary evaluation of the literature was completed. Subsequent to these literature searches
the IRIS Multi-Year Agenda was published (U.S. EPA, 2015). The IRIS Program maintains an
agenda of chemicals for which assessments are either underway or to be initiated. The IRIS
Program recently published the IRIS Multi-Year Agenda that lists a total of 37 chemicals (U.S.
EPA, 2015). In this plan the chemicals on the IRIS 2012 agenda were re-prioritized to determine
which assessments should be initiated in the next few years. In addition, some chemicals that
were not part of the 2012 agenda were identified and included in this re-prioritization. The top
priority chemical assessments are those with the highest potential public health impacts and/or
exposure and would be useful in anticipated EPA decision-making.
Tables la through 8b in this appendix provide toxicity information on the 8 List A
chemicals that are included in the IRIS agenda (U.S. EPA, 2015). EPA reviewed available health
assessments from 2008 (one year before the Six-Year Review 2 was finalized) through
December 2015. EPA also conducted literature search from 2008 (one year before the Six-Year
Review 2 was finalized) to December 2014.
Tables with numbers ending with letter "a" provide summary of EPA Assessments.
Tables with numbers ending with letter "b" provide summary of relevant non-EPA Assessments.
For each chemical table numbers ending with letter "a" provides the basis for the current
National Primary Drinking Water Regulations, including RfDs and cancer groups on which the
MCLGs are based, and assessments by IRIS, and OPP that postdate the date for the regulation
(through December 2015). These tables provide information on RfDs, including the critical
effect, citation for the principal study, point of departure (whether it is a NOAEL, LOAEL, or
BMDL), and breakdown of uncertainty factors from EPA assessments. In addition, for cancer
assessments, the year of the guidelines followed is presented, since the approach varied with the
year of the guidelines. For a number of the chemicals evaluated between 1996 and 2001, the
assessment document provided the assessments under both the 1986 and 1996 guidelines. In such
cases, only the assessment under the 1996 guidelines is provided in the tables in the IRIS and
OPP columns. Additional information on the quantitative portion of the cancer assessments is
presented in these tables for chemicals for which quantitative assessments are available. The
table shows both the quantitative assessment and the methods used for modeling the data and for
extrapolation from the animal data.
Assessments by other organizations which were completed within the scope of this
review (August 2008- December 2015) for List A nominated chemicals for health assessment are
presented in tables with numbers ending with letter "b". The citation to WHO refers to their
Drinking Water Guidelines, and if another organization within WHO (JECFA, JMPR, CICAD,
EHC) has a different value than WHO, it is noted.
All the U.S. EPA documents and references for the non-EPA assessments are listed in the
reference section.
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Six-Year Review 3	SUMMARY HEALTH EFFECTS ASSESSMENT REPORT	December 2016
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~j ~ = "ir
||
f ^ — =
° ~ ^ 2
'j 0 j. ¦*»
= > ^ 0 5
w - £ -
u- =
0 —¦ 2
*" ¦ 'j ~
— — -/ ¦ -
!p §. O —
2 UJ
Q •— ^
G p 3
~ -
2 0 0^2
||
^ ^ § S uj i
*j ' 1 0
= > ^ 0 3
w - £ -
( adiuiiim
(IWIU)
		
i)i)()5
0 0005 ()0()5
ii.o\i:i.) ludii.
lol.) esiimaled
l.() \l !l. 111 liiiniaii
siud> keual
d\ sliiucliou l i'ilvru
el al . Il>"4
1). \ol
classifiable as in
human
caiciiHiueuieil> b\
llie oral mule of
C\pnslllV ( l'JS(i|
mi idol Mies)
O.IS
:5".,
Winer"-11 D005 < I'JXXdi
0005(\O\i:i.) loilolh
Smuilieaui proteinuria
|\u«d 0 001 d'WSd) ool
<\0\i:i.) lodolh
Smiiilieaui pioieiuuria
1 l>X5e
151. Probable
human
caieiuoueu. \o
(|iiauiiiali\e
assessment for I he
oral route ( I'M.i
uuidel 1 lies.
I'JSi.hi


7	This departure from the default RSC of 20% was based on evidence of greater bioavailability from water in comparison with food (54 FR 22062).
8	Since the fraction of ingested Cd that is absorbed appears to vary with the source (e.g., food vs. drinking water), different % absorption was used for food and
water in the toxicokinetic model used to extrapolate from concentration in the kidney to intake in food or water; i.e. 2.5% absorption of cadmium from food and
5% absorption of the total cadmium dose from water. The model also assumes that 0.01% of the total body burden of cadmium is excreted per day.
9	Based on the revised "Group Bl" cancer classification, under the EPA 1986i cancer classification system, the MCLG for cadmium could be potentially revised
to zero, however, the Agency believes that an updated assessment is needed based on the most current 2005a U.S. EPA cancer classification guidelines.
55

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Six-Year Review 3	SUMMARY HEALTH EFFECTS ASSESSMENT REPORT	December 2016
Table lb. Summary of Assessments by Other Organizations: Cadmium CASRN 7440-43-9
( homiciil
ATSDK
( iill.PA
WHO
Includes Jl.< 1 A.
JMPK.Cl( Al). I.IK
lloiillh ( iin;i(lii
N AS
(j win
IARC
(jesir)
MI.IIS
(> Oil r)
U, u
— - S —
— —' — —
—	5 :¦> ? := ^
cd. OJj CL b O UJ
—	-~ _ ^ . --
^ ~ - -r
CJj C3 IS) r j
S - Q. P U-
~ —
~Sij
¦=£ Tr
CD
— 'J
**.
¦= -
s
'J - •_
¦> r:
SCO
¦" s.
~.
Q 5
H 5 c-
V w =0 yj
x> 4 JS °
~z. — ~
H
2
—
5 =
= l— o
. ¦ - f. ** ¦
O C/l
~
- O C. —
~ X) — ^
5 o 5 C 'i.
a da " "
w -
S
o r: ¦_
-> r:
c c o
¦" ~.
( adiiiiiini
(1 ()0()| (dll'milC \lkl.)
-
-
0 nil ' II1U 1.
~
-
~
--
(iiiuip 1.
Knmx ii u»

(:oi:i Dimiir,


piin isuHial




( aiciiinucmc
he a liiiniaii

mu kii da\ (I (1)1. i


lulenihle weekK




lo humans
caiciiinueii

I I"ol" ' 11 llli-H)


nilakc (2o| hi.




i:ui:e)
i:ol4)




WHO)






Note: ATSDR assessment for cadmium only provided quantification of noncancer effects, and there is a need for a cancer dose response assessment. From the
primary literature review EPA found several studies reporting both cancer and noncancer effects (e.g., neurodevelopmental outcomes, cardiovascular effects),
and at the minimum these studies need to be further evaluated (Ciesielski et al. 2012, Larsson et al., 2015a, Larsson et al., 2015b, Nawrot et al., 2015; Tellez-
Plaza et al., 2012, Akesson et al 2014).
10	UCDLio is the 95% lower confidence limit on the estimated internal cadmium dose (urinary cadmium expressed as ug/g creatinine) corresponding to the
probability of 10% excess risk of low molecular weight proteinuria.
11	Using the MRL of 0.00011 mg/kg/day and assuming 70 kg body weight, 2 L/day water consumption, and a 25% RSC, an MCLG of 0.001 mg/kg/day is
derived.
56

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Six-Year Review 3	SUMMARY HEALTH EFFECTS ASSESSMENT REPORT	December 2016
Table 2a. Summary of EPA Assessments: 1,2-Dichlorobenzene (o-Dichlorobenzene) CASRN 95-50-1
Chomiciil
(l)iilc of
rciiiilalioni
I .S. I.PA/OW National Prima r\ Drinking Wsilcr
Kouiihilion (\PI)\\ R)
l .S. I-'.PA IRIS
I .S. I.l»A OPP
w
CJ
'	
/. —
7 O
ed
_ ^
=P -n-.
= _
w --
~ = 3 '=¦
1 H J
cc n. o O
o ^
s  tV;
KS(
lis 11
cX) • — ^ O
=o E -a o
c ^ S. p u
-s O 'J — _
'— — n; y
0£ U.
_
2 o s
B % % g y g. -a
(/} ^ — O
c/) — — £2 —
-f; t— H. " - "
J - r y = - =
0 b ^ ^ ^
'J -j 0 " ^
= > - J
0 — " <5
|| ^ f |
CX) > O
Z, d Z
- 5 -5 33
—	— — S.J
—	— X ™
r: — ¦ ¦
0 0 -
c- — ~ ~
o£ u_
_
2 0 'j s
Ssl 5 y EL •a
y. — — — — —
 ^ — S — C .£
— vJj C/5 f/5
^o|i|u1
= > - j
0 — - <5
i.:-
l)ldlllil\>hCMA.'IIC
ui-Diclilnrnheii/eiie)
(IWlm
()(.
()(.
(I o<> S5 "
<\<>\i:i.) looo
( loll. 10 \. |0|)l
\n liv;ilniciil-
relaled ad\ ci'sc
effects nolctl.
renal luhiilar
rcuciicralinn
Milled hill nol
iiilerpreled as
dose-relaled
Ml' IW5
1). \m classiliable
as u< human
carciiinueiiicilv
(l'JS(n uuidelilies>
3
:o"„
OO'H iWJai
s5 -(\o\i:i.)
loom ion. io \.
|0|)). \n
ireaimenl-relaled
ad\erse eHeels
nuled. renal
luhiilar
reueneralinn
timed hm ikX5
1). Nut elassi liable
as ik human
carciimuciiicih
i I'JXi.i uuidelilies.
IWJai


57

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Six-Year Review 3	SUMMARY HEALTH EFFECTS ASSESSMENT REPORT	December 2016
Table 3a. Summary of EPA Assessments: 1,4-Dichlorobenzene (p-Dichlorobenzene) CASRN 106-46-7
( Ih-iii ic;il
(Diilo of
rciiiilalioni
I .S. I.PA/OW National Priniiin Drinking \\;ilcr
Kouiiliilion (\PI>\\ K)
I .S. I-'.PA IRIS
I .S. I-'.PA OPP
U
/. —
j. z
Id
- ^
-n-.
= _
1 E- _ 1
^ _J 0 2
- '¦> z Z
^ = 0 ^
a i; T3 "
S " s . J
^ a~= fc
" y UJ
^ t_ S
Q ° £
2 0 0 ^ f
lll'lf ll
^ *3 ^ 5 m i
'¦> * '1 0 j-
= > ^ 0 5
w - £ —
0
¦/".
JI
UJ
>
lis 2
#11 i
CD - T3
— — — —£
~ Tl 'C- 'j
* 'j 'J -
C >,Q £
""
2 0 0 5
ji ~ ~ = "ir
|1
^ *3 ^ 5 m i
0 b ^ £ 1:
= > ^ 0 3
w - £ —
l|S 11
CX) O
Z, d C
i - =-2
1 0 0 ^ c
'2 ~ ~ = "ir
^llt |!
^ ^3 § 5 m i
'¦> * j 0 j-
= > ^ 0 ^
w - £ -
1.4-
Didiloiohcii/eiie
(p-Didiloiohcii/eiici
lI'K'il
()0_5
no"
u 1 150
(adjiisied Id"
niiz ku da\)
(\<>\i:i.)
IDDDIIDM.
ID \. |()S)
Renal conical
dcucncralioii
111 male nils
Handle I'JXO.
VIP. I'JX"
( . 1'ossihlc liiiniaii
carcinogen ( I'JSih
UllldcllllCs) I'lOlll
ral siud\
l\>leiic\ 2 Id per
iiiu ku da>.
Drinkinu waler
coiicciiiralioii al
Id risklc\cl.
1 S ID
111- 1.  1
\ol
linali/ed

D 1)25 (2nnXc)
25 (\() \i:i.i
1 Mill loll.
1 d \ 1 increased
1 in or wcmlil 111
males and
increased
alkaline
pliosphaiase
and li\cr
wemlil.
iniialioii 10 (il
iracl 111tannics
1 lamimloii and
1 hake. I'W5
\oi l.ikcK in he
( arciiioucmc 10
111111 kiiis helow
doses dial do 1101
pei'lnrh normal li\er
lionieosiasis (2D(i5a
uiiidelmesi (2nnxa
12 Six Year Review 2 Report also provides the following data from a mouse study: Potency: 6E-3 per mg/kg-day; Drinking water concentration at 10-5 risk level:
5.8E-2 mg/L.
58

-------
Six-Year Review 3	SUMMARY HEALTH EFFECTS ASSESSMENT REPORT	December 2016
Table 3b. Summary of Assessments by Other Organizations: 1,4-Dichlorobenzene (p-Dichlorobenzene) CASRN 106-46-7
( homiciil
ATSDR
( ;ih:p \
who
Incliitics .ll ( I- A.
JMPK.CICAI). I.IK
Health ( iiiiiidii
\AS
(jwir)
IARC
(jwir)
MI.IIS
Ije.ir)
-j 5 C-
a!. =0 yi
^ op ^
<=£ -v-
CJj C3
— 'J
**.
G ~
S
O - ¦_
-> r:
5 G o
¦" y.
Q 5
H 5 ^
.a w =o ==
x> " ^ °
^ .«*.
C3
"5 — ~
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2
5 5 i
= o
. ¦ - y. -
O t/)
~
- o o >
: £ '= SP ^ ^
^ 2 £T s "£• ^ -C-
" - i- i-
z d ^ " - i'- -
" .5 ^
o ^
s
o - ¦_
-> r:
5 G o
—
~
1.4-
Didilnmlvii/ciic
-------
Six-Year Review 3	SUMMARY HEALTH EFFECTS ASSESSMENT REPORT	December 2016
Table 4a. Summary of EPA Assessments: Di(2-ethylhexyl) phthalate (DEHP) CASRN 117-81-7
( Ik-iii ic;il
(l);ik' ill"
ivuiiliilidii)
I .S. I.PA/OW Niiiioiiiil Priniiin Drinking \\ ;ilcr
Rciiuliilion (\PI)\\ K)
I .S. I-'. PA IRIS
I .S. IP A OPP
CJ
'	
/. —
7 w
iz
- ^
=P -h.
= _
CJ 2
o|
-3 E s
cc n. o O
S <3 y *=
w Z. UJ
Q •= u_ 17-
S. ^ ^
2 y '¦> s
'¦= "2 = 5 6.S
s — — — — —
(/) ^ — — C —
¦f; t— E. " o
J - r i 3 - =
o b 9 Si s ^
y o -J "
- > - J
0 ~ " <2
r S-
-J *
UJ
>
cX) • — ^ O
S-o u
— — 	c ¦
c3 a. p uj
o o - _
'— — n; '
_
2 y o
S2'i 5 y EL •a
y. — — — — —
C/5 — — — S2 —
-H — i- ~
¦t - /J3- =
o b S ^
y o o "
= > - J
w ~ -
|| fefl
CJ) .= >5 > O
z* d -z
«^ = -§ O
C3 Q. p hj
/-V O O - —
Cr — ~
cC u.
—
2 o o s
S ^ 5 y S. ^
^ ^ ^
C/) Zr, ~ — — S2 —
-H ¦— =. £ - ~ o
J - r ^ 3 - =
o b 9" £ ^ ^
'J -j 'j " —
= > - J
0 ^ " <2
l)i(2-clh\ llicw h
phihalalc 11)1 !l ll'i
(iwldi
0
		
ll'HI.1
mi: |«>
 and
I.OML)
Increase in
relaliNC Incr
wcmhis
( arpciiicrcl
al . I')5'
152. hohahlc hiinian
carcmoucii (l'JS(n
UllldcllllCs)
I'oiencv ii o 14 per
nm ku da>.
Dmikiim ualcr
coiicciiiralion al l<>
risk lc\cl ' In
nm 1. i I5\\'i2 ^
l.iiicari/cd
ninliisiauc model
0 "
II (12 ( l'JS(ic)
l'Ml.()\i:i.)
1	
( lull.Ill \.
|u|. S lor less
llian chronic
siiids and
l.()\i:i.i
Increase in
i'clali\e li\er
wemhis
Carpeiiierel
al .
152. probable
human carciiiouen
i	I'JXih unidelilies.
I'Wdi I'oiencv
ii	(i 14 per
nm k» da>.
Driiikmu waler
coiiceiiiralion al In
risk lex el ' In
nm 1. iI3W)2 ^
l.iiiean/ed
mnliisiaue model


Nolo, lor du ""-elliN I how I) phihalale, IP \ identified now assessnieiiis on cancer classifications ( \ ( (i 111. 2010, I \ U ( "Mi I T, \ 11 I IS "'n 14. I CI!. 200Xj. 1'iiriher,
the Six-Year Review 3 literature search identified a new study (Lin et al., 2011) that reported impaired glucose homeostasis at 1.25 mg/kg/day upon in utero and
postnatal exposures.
60
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Six-Year Review 3	SUMMARY HEALTH EFFECTS ASSESSMENT REPORT	December 2016
Table 4b. Summary of Assessments by Other Organizations: Di(2-ethylhexyl) phthalate (DEHP) CASRN 117-81-7
( homiciil
ATSDK
CsilKPA
WHO
Includes .ll ( I-A.
JMPU. ('I('AI).
i: ik
llciillh ( iiiiiithi
NAS
ij win
IARC
Ijwir)
MI.IIS
ij win
-j ^ -n-
aZ =o ^
s ^ "
^ op ^
CJj C3
— 'J
-¦».
= ~
•— 	
O - ¦_
¦> '*> r:
= G o
¦" s.
E 5 ri
i-5C
u ~ =0 yj
^ .«*.
g s w
— ~
E—
.o
5 ^ i
S °
. • - ' y. «" ¦
O C/} N"-'
~
— "j Z>
5 x) ^ ^
•= a. = o
x- o -j w
.= da " -
^ ^
o ^
o - ¦_
-> r:
5 c o
¦" ~.
1 )i< 2-
elh\ IIie\> I)
phihalale
<1)1: i ii'i








(iiiuip 215.
lJnssihl\
eaivinoueiiie
In hiiniaiis
(2DI2I)
keasnnahh
anliapaled Ik
he a human
eaivmnueii
(2014)
61
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Six-Year Review 3
SUMMARY HEALTH EFFECTS ASSESSMENT REPORT
Table 5a. Summary of EPA Assessments: Mercury (Inorganic) CASRN 7439-97-6
December 2016
( hi'iniial
(l)iilo of
ri'iiiilalioni
I .S. I.PA/OW National Prima r\ Drinking Wsiicr
Regulation (\PI)\\ R)
1 .S. 1 PA IRIS
I .S. IP A OPP
CJ
'	
/. —
7 C
ed
_ ^
=P -h.
= —
CJ 2
- -d '"5 |
1	H
s <3 2 *=
w _ -O UJ
2	LU l/l'
^ ^
2 o o
S % •= 5 y EL
(/) Z ^ — O
c/) — — C —
¦f; t— H. " i5 T< o
J - r i ¦=¦ - =
o
J. -j 'J " —
- > - J
O ~ " <2
l)\\ 1 !l. mm I. > tV;
RS(
Is fell
cX) • — ^ O
=o 5 -a y
^ ^ ^ CX
0 S a. 8 uj
^ -j j - _
'— — n;
_
.2 o
~2 = 5 5 ±~3
(/} — 2 Z ^ -?* O
(/} —
-H 7 o
•J - r * 3 - =
O = -3 £ ^ ¦-
J. -j 'j " ±
- > - J
0 ~ " <2
|| fefl
CJj > O
S d -Z
«^ = -§ O
— — — ' ¦ ->
—
r: — -j ¦ ¦
-• -j -> —
c- — ~
VC u_
2 o '¦> t.
sl'i 5 y a.-®
y. — — — — —
 - J
0 ~ <2
Mercurv
( IlKH'UaillC)
(IWIUI
o (Hi:
		
o ooo i loooiNni
specified) Mercuric
chloride-induced
;iuloi iiimiiiic
dnmcruloucphrnis
I'W-j. Druel cl al .
ll>"X; 1 jci ikiikImi el
al . I'JSI . \iulres
l'JS4

n.nl
:n"„
	)(H ( I'JSSn
n ?|" (l.o\i:i.i
|000(|0\.||. nil..
InSi Mercuric
eliloi'ide-iiiiliieeil
aiiloiiiiiiiiiiie
dnnierukiiiephriiis
IWj. Druel el al .
1TS: IJeniaiiiliii el
al.. I'JSI. X ml res.
I'JS4
Mercuric chloride
( . I'ussihle hiimaii
carciiinueii h\
I'JSih miiilelnics.
1  Inicrciirv ( .
I'ussihle hiimaii
carcinogen h\
11>S(h miidclnics.
1 
-------
Six-Year Review 3
SUMMARY HEALTH EFFECTS ASSESSMENT REPORT
Table 6a. Summary of EPA Assessments: Nitrate (as N) CASRN 14797-55-8
December 2016
( homiciil
(l);ili- of
rciiiilalioni
I .S. I.PA/OW National Prim an Drinking \\ siier
Regulation (\PI)\\ R)
I .S. I.PA IRIS
I .S. IP A OPP
CJ
/. —
7 C
Id
_ ^
= _
w /-
- -± '-= ¦£
IIP
G •= u. -S-
& £ => ^
2 o
Ssl 5 y §L •a
y. — — ~
 - J
0 — " <5
-J *
UJ
>
flMl
cd • — ^ O
E T3 o
^ ^ ^ ex
^ c3 S. 8 uj
<¦* -j o - _
'—
cC u.
_
2 o ¦-> s
B % % g y EL -a
C/5 — — C —
7* t— H. " i£! T< o
J - r ~ 3 - =
O = -3 ± * -
y o o "
= > - J
0 — " <5
|| fell
cij> O
Z, d -Z
«^ = -§ O
— x ™
r: — -j ¦ ¦
-• -j -> —
c- — ~ v.
0£ U.
_
S o 'J o
S ."2 -i 5 y Q. -a
;/> — s z ^ ~ o
wo <— S — C .£
C3 B ^ f/)
^o|^|ui
= > - J
0 ^ " <2
\ilialc (as \ i
(l^lu)
III
ID
1 .(> iiilialc-iiiiinucii
1 (> ( Id IIIU I.I
<\o\i:i.i 1
MellieiiKiulnhiiieinia
mi iiilaiils ISiisdiel
al . ll>5o. W allnii.
1 1

III
1 (> iniraie-
inimucii
(IWOCI l.(.
I ID 111- I.I
i\()\i:i.i 1
MclhciiHidnhi
iicniia in
iiilaiils I'mscli
el al . l^5o;
Wallmi. 1 lJ5 1



14 Nitrate assessment is based on the concentration in the drinking water for an exposed human population.
63
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Six-Year Review 3	SUMMARY HEALTH EFFECTS ASSESSMENT REPORT	December 2016
Table 6b. Summary of Assessments by Other Organizations: Nitrate (as N) CASRN 14797-55-8
( homiciil
ATSDR
( ;ih:p \
\\ll()|;
Includes .IIXTA.
.IMPK.CICAI).
I.IK
lloiillh ( iiiiiidii
\AS
(jcsir)
1 ARC
(jwir)
MI.IIS
Ije.ir)
_ ¦= =
0£ CD ~
2 ^
^ op ^
CJj C3
— 'J
-¦».
2^
	
O - ¦_
-> r:
5 G o
¦" /.
•W /
n 5
i-5C
w cfi =3
-C -i —
^ _S.
— ~
E—
.5
5 5 i
= — -j
. ¦ - y. -
O (/i
~
-	-j c. —
-	^ ^ ^
= E. = .- 5
^ ;j -j w
^ da " -
" " ?
O w
O
'J ~ -
¦> r:
= G o
¦" s.
Nilrale (as \ i



5o mu 1.
(2<)I lh.
wmo)

Niliale. 45.
et|in\ alciil lo
lo niu 1.
MAC inliale-
inimucii
(:un)




15	WHO refers to Drinking Water Guidelines, unless otherwise specified. If another organization within WHO (JECFA, JMPR, CICAD, EHC) has a different
value than WHO, it is included as a separate line. If another organization reports the same value as the WHO, it is indicated by footnote.
16	Guideline value is presented as mg/L only.
17	The noncancer value is presented as mg/L only. The value is derived by dividing the NOAEL which is a concentration in drinking water for humans by the
uncertainty factor.
64
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Six-Year Review 3
SUMMARY HEALTH EFFECTS ASSESSMENT REPORT
Table 7 a. Summary of EPA Assessments: Nitrite (as N) CASRN 14797-65-0
December 2016
( lK-mk';il
(l)iilo of
rciiiilalion)
I .S. I.PA/OW National Prim an Drinking \\ siicr
Rciiiilalion (NPDW R)
I .S. I-'. PA IRIS
I .S. IP A OPP
CJ
'	
/. —
7 C
Id
_ ^
-R-
= _
1 S J
n. o ^
^ ° ^5 —
>;
5	 uj
Q •= u_ 17-
6	£ => ^
2 o '¦>
5s-= 5 § EL "S
(/) — s Z ^ — O
C/) ;^r —
1 = ' i- /
J o 5 V 3 - =
o
J -j " —
= > - J
w ~ -
3 '/
_ -
UJ
>
ll = 13
5 -o o
— — •— s ¦ J
s S. p u
O J - _
'— ^ — J
cC u.
2 o
sll 5 § EL'S
y. — — — — —
c/) — — £2 —
-H — =. ~
J - r y =¦¦ - =
-J = 73 £ ^
'j. -j 'j " ~
- > - j
0 ~ <2
|| fell
CD.= ^
Z, d C
= -§ y
— _____ ¦_ S.J
N™, U- c
C3 O. p MJ
~ 'J O - —
— — y.
0£ U_
_
.2 o 'j o
r 1 i [j i
c/j S ~ £2 —
¦7: t— H. " - 7 o
J - r i =¦ - =
-J = -3 ± ^ -
J. -j 'J " ±
- > - J
w - -
Nil rile (as \ i
(IWIU)
1
1
ii. |(> inline- niiRiucn
\ilialc RID nf l .(>
Miliak'-iniinuen 1
(\1l loi
MelheiiKiukihinemia
mi inlanls Unsdiel
al. \\allmi.
1 1

1
() 1 iiiiriic-mlRiucii
(I'JXi.h 1 (lo niu 1.
iiilialc-iiilinucii)
(\()\i:i.i 1 (\1l-"
10)
MclliciiRiukihiiicmia
mi iiiraiils Wallmi.
1 «>51



18 Extrapolated from nitrate RfD of 1.6 mg/kg-day, assuming 10% of nitrate converted to nitrite. Assumes a 4 kg child ingesting 0.64 L/day.
1910 mg/L converted to 1.0 mg/kg-day assuming 10 kg child ingesting 1 L/day.
65
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Six-Year Review 3	SUMMARY HEALTH EFFECTS ASSESSMENT REPORT	December 2016
Table 7b. Summary of Assessments by Other Organizations: Nitrite (as N) CASRN 14797-65-0
Chomiciil
ATSDR

\\ IK)2"
Includes .11 CI-A.
JMPR. CICAI).
I.IK
lloiillh ( iiiiiidii
NAS
(\c;ir)
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(> oil r)
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(\c;ir)
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20	WHO refers to Drinking Water Guidelines, unless otherwise specified. If another organization within WHO (JECFA, JMPR, CICAD, EHC) has a different
value than WHO, it is included as a separate line. If another organization reports the same value as the WHO, it is indicated by footnote.
21	Guideline value is presented as mg/L only.
22	The noncancer value is presented as mg/L only. The value is derived by dividing the NOAEL which is a concentration in drinking water for humans by the
uncertainty factor.
66
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Six-Year Review 3
SUMMARY HEALTH EFFECTS ASSESSMENT REPORT
Table 8a. Summary of EPA Assessments: Uranium CASRN 7440-61-1
December 2016
Clii'miciil
(Diilo of
ri'liulalioin
I .S. I'.PA/OW National Prima r\ Drinkinii \\ alor
Rciiuhilion (\PI)\\ K)
1 .S. I PX IRIS
I .S. IP A OPP
O
CJ
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It
- /
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= _
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^ = 3 '=¦
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p
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2 o o
S % ¦= 5 y EL "2
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is) — s Z ^ ~ O
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|| fell
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—
r: — ^ • •
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0
0 (P,
(I'casihilils
and cusi-
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mu ku da>
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(loll. ^ \. M.i
(ii ii i ii n hi i ii
i.o\i:i.i
Renal ln\icil>
(lilmaii el al .
1 'WX
\. Kik<\\ ii liiiniaii
cai'ciiRiuen. No
t|ii;inlil;ili\ e
assessmeiil (ll>X<>i
mndeliiiesi
:<>
uu 1.
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		 I'JS'Vl
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		ii mii. iu\.
1 us> Initial hnd\
uemlil loss,
moderate
iieplirnli>\icil>
Mas nil id and
Undue. I'M'J



23	EPA ORIA is the principal health assessor for radionuclides. The 2000 radionuclides rule was a collaboration between EPA OW and ORIA. See 40 CFR 141.
24	The Office of Water Criteria Document (U.S. EPA, 199If) has derived risk specific concentration for a cancer risk of 1 x 10 4 for lifetime consumption of
various isotopes of uranium using the RADRISK program. For example, for combined U234 and U238 a concentration of 120 pCi/L is associated with a 1 x 10~4
cancer risk.
25	The IRIS RfD for natural uranium has been withdrawn. The Uranium entry in the Table is for Uranium, soluble salts.
67
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Six-Year Review 3	SUMMARY HEALTH EFFECTS ASSESSMENT REPORT	December 2016
Table 8b. Summary of Assessments by Other Organizations: Uranium CASRN 7440-61-1
( homiciil
ATSDK
( iill l'A
who
Includes Jl.( I-A.
JMI'U. ('I('AI). I.IK
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Note: For uranium, a number of peer reviewed studies were identified since Six-Year Review 2. The new data on the noncancer health effects of soluble uranium
from oral exposure include bone effects and kidney damage is considered in the NPDWR.
68
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Six-Year Review 3 SUMMARY HEALTH EFFECTS ASSESSMENT REPORT
Health Effects Assessment
December 2016
APPENDIX B - LIST B TOXICITY TABLES FOR CHEMICALS THAT ARE
EVALUATED FOR POTENTIAL IMPACT ON THE MCLG
Tables la through 42b in this appendix provide key information on the 42 List B
chemicals evaluated in this assessment. EPA reviewed available health assessments from 2008
(one year before the Six Year Review 2 was finalized) through December 2015. EPA also
conducted literature search from 2008 (one year before the Six Year Review 2 was finalized) to
December 2014. Tables with numbers ending with letter "a" provide summary of EPA
Assessments. Tables with numbers ending with letter "b" provide summary of relevant non-EPA
Assessments. For each chemical table numbers ending with letter "a" provides the basis for the
current National Primary Drinking Water Regulations, including RfDs and cancer groups on
which the MCLGs are based, and assessments by IRIS, EPA OPP and/or OW (fluoride only) that
postdate the date for the regulation. These tables are numbered la through 42b and provide the
basis for the RfDs, including the critical effect, citation for the principal study, point of departure
(whether it is a NOAEL, LOAEL, or BMDL), and breakdown of uncertainty factors. For EPA
OPP assessments, the Food Quality Protection Act (FQPA)26 factor is also provided, when
relevant. In addition, for cancer assessments, the year of the guidelines followed is presented,
since the approach varied with the year of the guidelines. For a number of the chemicals
evaluated between 1996 and 2001, the assessment document provided the assessments under
both the 1986 and 1996 guidelines. In such cases, only the assessment under the 1996 guidelines
is provided in the tables in the IRIS and OPP columns. All supporting U.S. EPA documents are
listed in the reference section. Additional information on the quantitative portion of the cancer
assessments is presented in these tables for chemicals for which quantitative assessments are
available. The table shows both the quantitative assessment and the methods used for modeling
the data and for extrapolation from the animal data. If an IRIS or EPA OPP or OW assessment is
the Relevant New Assessment on which to base a potential change to the MCLG, the information
has been bolded in the table and the basis of the calculation for the potential new MCLG is
provided in a footnote.
Assessments by other organizations which were completed within the scope of this
review (August 2008- December 2015) for List B chemicals are also presented in tables with
numbers ending with letter "b". Where possible, non-cancer PODs initially expressed as water
concentrations were converted to the reference value in dose as mg/kg/day, so that all values
could be directly comparable at a glance. The citation to WHO refers to their Drinking Water
Guidelines, and if another organization within WHO (JECFA, JMPR, CICAD, EHC) has a
different value than WHO, it is noted.
26 The FQPA mandated consideration of an additional uncertainty factor to ensure protection of children for
pesticide safety evaluations.
69
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Six-Year Review 3
SUMMARY HEALTH EFFECTS ASSESSMENT REPORT
December 2016
Table la. Summary of EPA Assessments: Alachlor CASRN 15972-60-8
( Ik-iii ic;il
(Diilc ol'
ivuiiliilioiii
I .S. I.PA/OW Niiiioiiiil Prim an Drinking
\\;i(er Roiiiihilion (\PI)\\ K)
1 .S. I-'.PA IRIS
I .S. IP A OPP
CJ
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/. —
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Id
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= _
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| S 5r
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^ ° ^5 —
2 <3 a !=
w Z. •£> UJ
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o b ^ •£. ^ ^
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flfell
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(/) _ — — C —
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O = -3 ^ ^ ¦-
'j. -j 'j " ~
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0
o oo:
(I'HI.)
DDI I
mu k» da>
(\<)\i:i.'i ido
( lull. |() \)
1 leniosiderosis
. he mo l uie
anemia
\a\lorel al .
IW4
132. hohahle
huniaii carcinogen
(I'JXiii uiiidolilies)
() '5
MU 1.
0	1)1 ( IWlh) I
mu ku da>
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henioh lie
anemia
Moiisanio. ll>X4

0.005 (200(i;i.
2007C) / 0.5
iii^/k^/(l:i>
(NOAII.!/
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I0A)/
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iisscssmcnl/
n;is;il in mors
l.ikck in he a
hiinian eareiiioueii
al liiuh doses, noi
likel\ In he a
human carcinogen
al low doses
(2oo5a unidelilies.
:Od(,;|) 0 005
nm ku da>
Nonlinear \l() \
33	The current MCL is based on a PQL of 0.002 mg/L, neither analytical nor treatment feasibility would be a limiting factor for a possible higher level of 0.04
mg/L for the MCLG.
34	The data indicate that alachlor's tumorigenicity is operating by a nonlinear mode of action. OPP (U.S. EPA, 1998d, 2001b, 2006a) concluded that alachlor
causes nasal turbinate tumors via the generation of a reactive metabolite that leads to cytotoxicity and regenerative proliferation in the nasal epithelium; sustained
cytotoxicity and proliferation is needed to lead to neoplasia. Based on this MOA assessment a non-linear dose response assessment is appropriate. Therefore,
using the POD of 0.5 mg/kg/day identified by OPP for this endpoint and the UF of 100 (10H, 10A) would result in a health reference value of 0.005 mg/kg/day.
Assuming 70 kg body weight, 2 L/day water consumption, and a 20% RSC, a MCLG derived from this value is 0.035 mg/L (rounded to 0.04 mg/L). If
determined appropriate to revise the new potential increased MCLG would be based on the nonlinear cancer assessment.
70
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Six-Year Review 3
SUMMARY HEALTH EFFECTS ASSESSMENT REPORT
Table 2a. Summary of EPA Assessments: Antimony CASRN 7440-36-0
December 2016
( Ik-iii ic;il
(l);ik' ill"
rciiiilalinni
l .S. I.PA/OW National Prim an Drinking \\ ;ilcr
Kciiiiliilion (NPI)\\K)
I .S. I-'. PA IRIS
I .S. IP A OPP
U
CJ
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7 C
ed
- ^
=P -n-.
= _
w ^
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9 •== u_ ^
& £ ^ ^
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i 5. : 7 7 : =
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C= a. 3 u3
= 2.* ¦£ 7
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2 o 'j o
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7 1 i i i i-1
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CJ) .= >5 > O
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< i'w:hi
()()()(,
0 ()()(.
(PHI.)
		 n 4 -
-------
Six-Year Review 3
SUMMARY HEALTH EFFECTS ASSESSMENT REPORT
Table 3a. Summary of EPA Assessments: Asbestos CASRN 1332-21-4
December 2016
( homiciil
(l)iilo of
ivuiiliilioni
I .S. r.PA/OW Niiiioiiiil Priniiin Drinking \\ ;i(er
RiliiihKion (NPDW K)
I .S. I-'. PA IRIS
I .S. IP A ()l»l»
CJ
'	
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7 C
Id
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= _
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| S
CD Q. O ^
^ ° ^5 —
^ a
s <3 a 8=
w Z. uj
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<*¦ S. ^ ^
2 o
'¦= "2 = 5 5 £."2
— — — — —
C/5 — — — C —
-H — =. '¦ - ~ o
J - r i 3- =
o b 9 •£. ^ ^
J. o o " .=:
- > - J
C ~ " <2
fc.
j c
UJ
>
|| si!
cd • — ^ O
S d C _
=o E ~o o
— _ —
0 c3 a. 8 uj
^ -J o - _
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2S ~
2 O
S :s •= 5 y g. -a
(/) — 2 — ^ 'f O
c/j — — £2 —
¦j" L. = W - "i? o
J - r ^ 3 - =
o b ^ ^
J. -j 'J " —
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|| fefl
CJj ^ > O
— — — ' ¦ ->
— — X "
r: — -j ¦ ¦
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c- — ~
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2 o '¦> t.
Si! 5 y E. ^
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\shes|ns
(IWlm
~ million
lihers 1.
~ milium
lihers 1.

\ol a\ ailahle \ la
inuesimii. \. Knowii
hiiniaii carciimueii
( I'JSih miuleliiies) \ ki
iiihalalkin Kneiics
14 In per'fiber 1..
Drnikiim \\;ilcr
eniiceiiiralkm al Id
risk le\el "I In
liherl. (15 \Vi2 ^
l.iiieari/eil miiliisiaue
n mile 1

	i:ol4ai
\ci: \ ikisi
\nl a\ailahle \ la iimesium : A.
kimu ii hiiniaii eareiimuen \ la
inhalation i I'JSih mmleliiies.
IWhi
l.ihh\ amphihule ashesins is
eareiimueine In liiiinaiis \ la
iiilialaimn (2ul4a. \( l!.\ IKISi


35	An oral RfD was not derived because inhalation is the primary route of concern and oral data for Libby Amphibole asbestos is lacking (U.S. EPA, 2014a).
36	The IRIS reassessment of the noncancer health risks resulting from exposure to asbestos (from Libby Montana) identified during the first six-year review (U.S.
EPA, 2002b) was still in progress as an external review draft submitted to the Science Advisory Board (SAB) in 2012.EPA/IRIS (2014a) is cited in the table.
37	The External Review Draft of the IRIS Toxicological Review for a mixture of amphibole fibers identified in the Rainy Creek complex and present in ore from
the vermiculite mine near Libby, MT could not assess oral carcinogenicity (U.S. EPA, 2014a); however, Libby Amphibole asbestos is considered carcinogenic to
humans by the inhalation route of exposure by 2005a EPA cancer guidelines.
38	Oral carcinogenicity could not be assessed in the IRIS external review draft for a mixture of amphibole fibers (U.S. EPA, 2014a); however, Libby Amphibole
asbestos is considered carcinogenic to humans by the inhalation route of exposure by 2005a EPA cancer guidelines.
72
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Six-Year Review 3
SUMMARY HEALTH EFFECTS ASSESSMENT REPORT
Table 3b. Summary of Assessments by Other Organizations: Asbestos CASRN 1332-21-4
December 2016
( homiciil
ATSDR
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q; a «
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\ll I'nrms nf
aslvsins
ichiAsniile.
andilnlilc.
anmsiic.
liciiinlilc.
auiiinlilc and
aiillmplis II He i
(llHlip 1.
('araimueiiii;
In liiiniaiis
i:oi:ci
Knnw ii In he
a liiiniaii
caiviiinucii
i:u|4i
73
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Six-Year Review 3
SUMMARY HEALTH EFFECTS ASSESSMENT REPORT
Table 4a. Summary of EPA Assessments: Barium CASRN 7440-39-3
December 2016
( hemiciil
(l)iilo of
ivuuliilioii)
I .S. I.PA/OW Niiiioiiiil Priniiin Drinking \\ ;i(er
Rciiiiliilion (\PI)\\ K)
l .S. I-'. PA IRIS
I .S. IP A OPP
U
CJ
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Id
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t°ls
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C/5 Zr, ~ — — £ —
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J - r y. - =
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w - -
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I'ma. hi


39 Based on the 2005b IRIS RfD the MCLG could increase. The RfD is 0.2 mg/kg-day and assuming 70 kg body weight, 2 liters water intake per day, a DWEL
of 7 mg/L can be derived. This value is three times the current value. An RSC of 80% was determined using the Exposure Decision Tree approach described in
the Methodology for Deriving Ambient Water Quality Criteria for the Protection of Human Health (U.S. EPA, 2000b). The dietary component of the RSC
estimate was based on data from the United Kingdom Total Diet Study and not on data from the United States. Dietary data for the United States are not
available. The diet in the United Kingdom is relatively consistent with that in the United States and qualifies for use in the RSC analysis. Using and 80% RSC,
the potential new MCLG would be 6 mg/L.
74
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Six-Year Review 3
SUMMARY HEALTH EFFECTS ASSESSMENT REPORT
Table 5a. Summary of EPA Assessments: Beryllium CASRN 7440-41-7
December 2016
( hcmiciil
(Diilo of
ivuiiliilioni
I .S. I.PA/OW Niiiioiiiil Priniiin Drinking \\ siicr
Rciiiikilion (NI'DW K)
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iiiriiimniiilon
lesions ol siii;ill
ink-slinc/
Mor»iiivi(l20 ol
ill.. I')^.
( arciikiueinc
poleiilial ol
iimesled he i \ 11111111
eaniKii he
delermmed (ll>l><>
uiiidelines. I'WXci


40 The MCLG could increase based on the 1998c IRIS. The RfD is 0.002 mg/kg-day and assuming 70 kg body weight and 2 liters water intake per day, the
DWEL would be 0.05 mg/L. Using a 20% RSC, the potential new MCLG would be 0.01 mg/L.
75
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Six-Year Review 3	SUMMARY HEALTH EFFECTS ASSESSMENT REPORT	December 2016
Table 5b. Summary of Assessments by Other Organizations: Beryllium CASRN 7440-41-7
( hcmiciil
A 1 SDK
(iiir.PA
who
Includes JI'.CI-'A.
.IMPK. ('I('AI). I.IK
Health ( anada
\AS
(\e;ir)
IAUC
(j car)
/. —
= =
^ c
/ -
Qi p,
2 ^
^ op ^
CJj
~ 	
¦_
CJj C3
= ~
S
— 3
o r: ¦_
-> '¦> 71
= ¦-= 'j
•" i.
w (/)
f 2 =;¦
H 5 ~
.a ^ ~
¦e 2 ^
c 2 5p^
~z. — ~
H
2
Ms
5 °
r~ ' ^ .
O t/i
G
~ o 5
E S - ^
•E a. c r o
/ y 'j w
o ^
~
o r: ¦_
-> r:
= ¦-= o
•" y
•W /,
l!ei'\ Ilium








(iiiuip 1.
( ai'ciiinueiiic In
humans (2(i|2d)
kiinu ii Ui he a
human eaiemnueii
i:ol4i
76
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Six-Year Review 3
SUMMARY HEALTH EFFECTS ASSESSMENT REPORT
Table 6a. Summary of EPA Assessments: Carbofuran CASRN 1563-66-2
December 2016
Clii'miciil
(Diilo of
iviiuhKioin
I .S. I.PA/OW National Priman Drinkinii Walcr
Kouiiliilion (\PI)\\ K)
l .S. I-'.PA IRIS
I .S. IP A OPP
U
CJ
/. —
7 C
Id
_ ^
=P -n-.
= _
CJ 2
^ 3 '=¦
lip
= —
G •= u_
c£ ^ t;
2 o '¦> s
'¦= "2 = 5 5 £."5
— — — —
C/5
^ ^ ^ 775 — —
.'J ^ r >3- =
2 in — 2
= > - J
C ~ " <2
3
>cj
3 '/
_ -
UJ
>
c.
|| fell
cd • — ^ O
c, d -z _
E -a o
¦— •— s • J
- C 2 c: <-
w r: a. o uj
= 'i.e. ¦£ 7
~ - ¦—
_
2 o o
Sl-s 5 § EL ^
c/j Z ^ — O
c/) — — £2 —
-H ¦— =. £ - ~ o
J - r y =¦-- =
O = ¦= ± * -
'J. O o " ^
= > - J
w ~ -
lis = 3
d Z
= -§ a
— — — ' .
c: a. p m
~ o o - —
— -r y.
ai. d_
.2 o 'j o
"2 = 5 5 ~c-~5
4 5. 5 7 7 H ¦=
.'J - r >3- =
2 n — 2
= > - J
w - -
Carhol'uraii
0 04
o 1)4
0	005 o 5
(\()\i:i.) loo
(|0||. |0\)
\ccl> IcIihIiiicmc
rase inhibition
and testicular
dcuciicralioii
1	\1( Corp .
I'«.
1!. 1 idciicc of
iioiicaiviiioucmcih
( I'JXl.l illlidol 1IICM
o I "5
:o"„
	5 (
o 5 (\<>\i:i.)
100(1011.
lo\i RISC and
plasma
cholniesierase
inhibition. and
testicular and
uterine effects
lAKCorp .
I')S1

		3(200X;|)
4I/0.0J
(liMI)l.ln)/ 100
(ION. IIIA)
lii'iiin
acclvlcholiiK'sl
erase
inhibition in
PNDI Inialc
pups/ KMC
Corp.. 2005
\ol likcl\ Id he a
hiiniaii carciiiDuen
(2oo5a uiiideliiies.
:00(,;|)
41 OPP's value for carbofuran is an acute RfD for cholinesterase inhibition, which OPP has determined is protective of chronic exposures; the potential new
MCLG is 0.0006 mg/L assuming a RfD of 0.0003 mg/kg-day assuming lOkg/lL (children) and an RSC of 20%. OPP has also derived an aPAD of 0.00006
mg/kg-day based on this RfD to protect infants and children from neurotoxic effects (FQPA 5x). A chronic RfD was not derived because of the rapid recovery of
AChE activity and an acute exposure based RfD that is considered protective for chronic exposure. An alternate potential MCLG of 0.0004 mg/L can be derived
for children from birth to less than 12 months at the 90th percentile of 0.15 L/kg (U.S. EPA, 201 la Exposure Factor Handbook, based on Table 3-19) as follows:
0.0003 mg/kg/day x 0.2 x 10kg/1.5L = 0.0004 mg/L.
77
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Six-Year Review 3	SUMMARY HEALTH EFFECTS ASSESSMENT REPORT	December 2016
Table 7 a. Summary of EPA Assessments: Chlordane CASRN 12789-03-6 (IRIS), 57-74-9 (lit search)
( Ik-iii ic;il
(Dale ill"
rciiiilalinni
I .S. I-.I'A/OW National Prima rx Drinking
WiiliT Rciiiilalion (\PI)\\ K)
I .S. IP A IRIS
I .S. I-'.PA OPP
CJ
C—
/. —
7 C
ed
_ ^
-n-.
= _
-	-d ±
-3 = s .-
=X3 n. O ^
^ ° ^5 —
S  - J
0 ~ " <2
_ -
UJ
>
|| fell
cX) • — ^ O
—	z ¦- ^ -
=0?" 5 -O o
—		 — 	i ¦
C3 Q. P UJ
¦> zr _
'— — n; J
CC U.
_
2 y
5s-= 5 y Q.•a
c/j — s Z ^ — O
C/) Zr, ~ — — C —
-H ¦— =. - ~ ^
J - r * - =
o b 9" £ ^ ^
J -j 'j " —
= > - J
w - -
|| ^ f |
CJj ^
= -§ O
C3 CI. p nj
/-v o 'J — —
— y.
U-
—
2 o o s
5s-= 5 y Q. •a
y. — — — — —
c/j _ — — S2 —
<— B. % — 7. o
J - r ^ 3 - =
o = ^ ^ -
'j -j ~j " ~
= > - j
0 ^ " <2
( lilnrdane
(lwi»i
0
u.oo:
I.)
		)05
0 045
d .() \l l .i
loom loll.
IDA. |0|.)
I.ixer
necrosis mi
male rals
Yniicmiira el
al . I')S?
1 >2. I'ruhahle liiinian
carcnm-cn (1 *JS(ii
mndcliiicsi
I'uleiicx 1 ' per
iiiu ku dax.
Driiikinu xxaler
cimcciiiralimi al lo
risk lex el 2 ~ lo
in-1. (UWi: ^
l.iiicari/cd
miiliisiaue model

o 0005 il'Wi
o I5(\()\i:i.i
^oodoll. |o\.
'I)i 1 .ix er
necrosis mi
mice
Khasaxx inali
and (iiiiiseh.
IWI. IRIX
ITV \( I
vr~
l.ikelx in he a
carcninucii hx all
rniiies nf exposure
i I'Hi uuidelilies.
I'W) I'mencx o.^5
per iiiu ku dax.
Drmkiiiu waler
cuiiceuiralinu al lo
risk lex el 1 lo
in-1. (i:\\ )^ 4
l.iiiean/ed
innllisiaue mndel


78
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Six-Year Review 3
SUMMARY HEALTH EFFECTS ASSESSMENT REPORT
December 2016
Table 8a. Summary of EPA Assessments: Chlorobenzene (Monochlorobenzene)
CASRN 108-90-7
( lu'inical
(l)iilo of rouiihilifin >
I .S. I.PA/OW Niiii(in;il Prima r\ Drinking
\\;ilcr Rciiiilalion iNPDWK)
I .S. I-'.PA IRIS
I .S. IP A OPP
CJ
'	
/. —
•e a
iz
- ?
=P -n-.
= _
; = 3 =
|b ; =
=6 a. o O
^ O ^
"... - 7= y
S o a 8=
w Z. uj
G ¦ Ll. ^
<*¦ i£ ^ ^
2 o -j Z
'¦= "2 = 5 * ~5
I — — — — — ^
.i ^ = S 2 73
o i: 9" £ ^ ^
J. -j 'j " ±
- > - J
0 w " <2
JI
- •/.
-J X
UJ
>
S.
11 = = 1
11«
s— ~
- 7Z -J _
^ '-I 'J — _
'— — ~Z. 1
cC U.
_
2 o ¦-> |
<= !2 -H O § 8. "S
y. — — — — — ^
1' ^ ? Z 7 3
i - J V 3 - =
o = 9 ^ ^ -
J. -j 'j "
- > - J
O w " <2
_ c.
12 = 13
c£.= 75 > ^
— •_ S.J
j!ll»
2 -= -2
_
2 o -j 5
'¦= "2 3 5 i. ~5
(/) 2 j; J J „ O
^ i z 7
" ° S a #tsj s
J. o - 2
= > - J
0 ~ " <2
(liliimbeii/eiie
(\li<>~.
Knapp el al..
l<>~
1). \m classifiable
as in human
caicmouciiicih
(1 *JS(n uiiidelilies.
iimn


79
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Six-Year Review 3	SUMMARY HEALTH EFFECTS ASSESSMENT REPORT	December 2016
Table 8b. Summary of Assessments by Other Organizations: Chlorobenzene (Monochlorobenzene) CASRN 108-90-7
( homiciil
(l.isl A or li)
ATSDR
CsilKPA
WHO
Includes Jl.( I- A.
JMPK. ('I('AI). I.IK
Ik'iihh (iiiiiidii
\AS
IAKC
(jean
Ml. IIS
(jear)
-¦»
CJj _
^ s
o
" **.
5
CD
¦y
CJj C3
= ~
s
~
' J - ¦_
-> '¦> 71
s s °
' /.
**.
B. ^
w Cfi -3
¦2 2 ^
C- C3 Cp """""
"s — ~
E—
3
% 5 =
s u o
. • - y. «" ¦
O c/} s—^
o
~ o 5
™ ^
•E a. s r o
* p o U >,
^ d ^ ^ "
O w
•— ~
'J T. ¦_
-> r:
= o
•" y. ^ •
W /,
( lilni'iiheii/eiie

0 (P
(2iil4i








42 The public health goal derived by CalEPA is based on noncancer effects. The RfD-equivalent shown was calculated based on the NOAEL and UF provided by
CalEPA for noncancer effects.
80
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Six-Year Review 3	SUMMARY HEALTH EFFECTS ASSESSMENT REPORT	December 2016
Table 9a. Summary of EPA Assessments: Cyanide CASRN 57-12-5
( homiciil
(l);Ko of
ivuiiliilioni
I .S. I.PA/OW Niiiioiiiil Priniiin Drinking \\ ;ilcr
Rciiuliilion (\PI)\\ K)
1 .S. I-'.PA IRIS
I .S. I.PA OPP
CJ
•	
/. —
7 C
Id
- ^
=P -n-.
= _
; = 3 =
1 H J
a. o O
^ ° ^5 —
is y
s <3 ^ *=
w _ X) Uj
Q u_ 17-
S. ^ ^
2 o ¦-> o
S2 = 5 y EL•a
c/j — ^ ^ ^ — o
(/) —
-H ¦— E. £ - ~ o
J - r * 3- =
o b ^ ^
J. -j 'j "
= > £ -j
0 ~ " <2
l)\\ 1 !l. mm I. > tV;
kS(
Is si!
CD • — ^ O
sr2 o 2 s: ^
E-o o
C5 ftpU
o o - _
'— ^ — J
cC u.
_
2 o 'j o
7 ~i s 5 i 8.
: 7 i ii
.'J - 5 'y 3 -
= > - j
0 ^
ll = 11
CD.= -73 > ^
= ¦§ 0
c: a. p m
~ 0 -J - —
o£ u_
_
2 0 '-> z.
5s-= 5 y 8.•a
y. — — — — —
c/j _ — — S2 —
7" t— pL $ - 7 0
.J - r y 3- =
0 = ¦= c * -
y 0 0 " ^
= > - j
0 ^ " <2
(\aiiidc (l'W2hi
u:
o:
002 1 o s
(\<>\i:i.) loo
( loll. 10 \)
(\ 11" 5 for
apparent tolerance
\ la fund compared
In water)
\hscncc of
clinical and
hisiolomcal
cffccls Howard
and 1 lan/al 1^55
1). \oi classifiable
as u< hiiinan
carciiioucincil>
(1 lJX)/
3	Kill.
I0A. I0S. 31))/
(locioiiso ciiudii
opi(li(l> mis
n eight/ N I P.
I«)«)3
Inadequate
information lo
assess I lie
carciiioueiiic
poleniial (2005;,
uiiidelines.
2o|oCi
0004 (2001 ,h)
04(I.O\i:i.i
loodoll. I0S1
( limcal smns
mcliidiim
nausea.
\oniinnu.
headaches.
di//iness
flic classification of
I lie carcmoueiiic
poleniial could 1101 he
delernimed due lo 1 lie
absence of accepiahle
cancer sindics 111 mis
and mice (2oo5;i
unideliiies. 2oi)(ihi
43 Using the RfD of 0.00063 mg/kg/day and assuming 70 kg body weight, 2 L/day water consumption, and a 20% RSC, a potential new MCLG derived from this
value is 0.0044 mg/L (rounded to 0.004 mg/L).
81
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Six-Year Review 3	SUMMARY HEALTH EFFECTS ASSESSMENT REPORT	December 2016
Table 10a. Summary of EPA Assessments: 2,4-Dichlorophenoxyacetic Acid (2,4-D)
CASRN 94-75-7
( homiciil
(l)iilo of
iviiiiliKinn)
I .S. I.PA/OW Niiiioiiiil Priniiin Drinking
Wilier Kouiiliilion (\ Pl)\\ K)
l .S. I-'.PA IRIS
I .S. IP A OPP
CJ
/. —'
7 C
iz
- ^
=P -n-.
= _
- 'o 1
w) n. o O
^ O ^
3 o a 8=
¦— UJ
s. ^ ^
2 o ¦-> Z
'-= "2 = 5 * ~5
y. — — — _ — ^
i n z 7 ^
i - r V 3 - =
¦j - — i. ^ ~
J. -j o " ^
= > - J
O ~ " <2
.1
- ¦/
-J *
UJ
>
11 = = 1
11 8
— — ¦ - ~ *—
- 7Z 'J —
^ -j -j —
C- Q ^ ts\
CC Ll.
.2 o ¦-> 3
"2 = 5 5 £. -3
y. — — — — — ^
n z 7 ^
i - r y 3 - =
O = ^ i ^ -
'J -j 'J " —
- > - J
O ~ " <2
_ s
|"S = H
CX) ^
=-8|
— s , J
^ § lp-
2 - ¦= - 1
2 o -j 5
£ -H o 5 EL "S
y. — — — — — ^
^ H z 7 ^
i - r V 3 _ =
-j : i ^ :
J. -j 'j " —
- > - J
O ~ " <2
2.4-1) (2.4-
l)ichli\i:i.)
loo
( loll.
10 \)
1lemalnln
UIC.
"."2 hepalic
and renal
ln\icil>
Seima el
al. I')S1

0.21 (20I3)44/2I
(NOAII) 100
(Kill. I0A)/
kidne\ (o\ici(\
1). \m classifiable
as In hiiniaii
carciiinucincil>
( I'JXih miidelnies)
44 The MCLG could increase based on the RfD from 2013 OPP. The RfD is 21 mg/kg/day, assuming 70 kg body weight and 2 liters water intake per day, and a
20% RSC, the potential new MCLG would be 2 mg/L.: 0.21 mg/kg-day x 0.2 x 70kg/2L = 1.47 mg/L, which is rounded to 2 mg/L.
82
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Six-Year Review 3	SUMMARY HEALTH EFFECTS ASSESSMENT REPORT	December 2016
Table 10b. Summary of Assessments by Other Organizations: 2,4-Dichlorophenoxyacetic Acid (2,4-D) CASRN 94-75-7
Chcmiciil
ATSDR
CsilKPA
WHO
Includes JIXTA.
JMPU. ('I('AI). I.IK
llc'iihh Ciiiiiidii
\ AS
ij win
IARC
ij win
MIIIS
ijwin
~ -I.
CI) w
CJj C3
— 'J
-¦».
s
'J 71 ¦_
-> r:
5 G o
¦" s.
Si w Cfi ~
x> " ^ °
"5 — ~
E—
5 0 i
= u o
(7l >>
~
-	o o
-	X) ^ ^
.= a. c 5
x- o o w
^ da " "
O w
	
o - ¦_
-> r:
5 G o
¦" ~.
W /
2.4-1) (2.4-
Didilni'iiphcikiw
acelic \cidi

I1.IH15
(2«l(l^;i l
Due In lack ol'cniicliisi\ c
lindiiius mi I lie
epidemiologic;!! dala. and
llic lack nl'e\ idence in
animal studies lor
caiciiioueiiicil>.
caiciiK)ueiiicil> is iml
used as ilie eiidpniiil lor
1 llC I'IKi (2()()'J;|)







45 The public health goal derived by CalEPA is based on noncancer effects. The RfD-equivalent shown was calculated based on the NOAEL and UF provided by
CalEPA for noncancer effects.
83
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Six-Year Review 3	SUMMARY HEALTH EFFECTS ASSESSMENT REPORT	December 2016
Table 11a. Summary of EPA Assessments: Dalapon (2,2-Dichloropropionic Acid)
CASRN 75-99-0
('lii'iii ic;il
(l);ilc of
ivuiiliilioni
1 .S. I PA/OW National Prim an Drinking \\ alcr
Rciiiilanon (NI'DW R)
1 .S. I-'. PA IRIS
I .S. IP A OPP
CJ
'	
/. —
7 C
ic
- ^
=P -n-.
= _
- 'd 'J. |
| S j;=
=6 n. o O
O ^
-... - -4 y
S o a 8=
¦— 'S- ^
G •— Lu 1/t'
<*¦ (£ ^ ^
.2 o Z
'¦= "5 = 5 8. "3
y. — — — ^ — ^
¦77 -1 E. '¦ - ~ O
J - r ^ 3 - =
o i: 9" £ ^ ^
J. -j 'j " —
- > - J
w ~ -
JI
- ¦/-.
-J 0£
LU
>
!l ^ o |
ii«
—		 •_ s ¦ J
—	¦ - — '—
- 7Z -J _
~ O O - _
'— — ~Z- 1
CC Lu
_
: o -j Z
'¦= "5 = 5 £. ~5
y. — — — — — ^
H z 7 ^
y - r v 3 _ =
O = -3 i ^ -
J -j "J " ^
= > - J
w - -
_ c.
12 = 11
CD.= 73 > ^
=-§£
— _ — S.J
"• -j ~ ^ —
-¦ — ~ f
_
2 o -j 5
= "2 = 5 5 * "3
(/i - ^ j J « O
i H z
i - r V 3 _ =
O = -3 ^ ^ -
^ ;j 'J " ^
= > - J
w - -
Dalapnn (2.2-
Diclilnmprnpkiiiic
\cid)( l'W2h)
(1 2
0.2
mil S
(\o\i:i.i
loo (loll.
10 \. 1|)|
Increased
kid ne>
uciulil
l'a\ nier el al .
1 <><.()
1). \nl classiliable
as in human
carciiinueiiicilv
(1 lJS(n uuideliliesi
0 <>
20".,
o.oi (I'WSei
X 45
(\o\i:i.) loo
(loll. 10 V
11)) Increased
kidne> In hi»d\
weiulil ralin
l'a\ nier el al..
1 •><.()



84
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Six-Year Review 3	SUMMARY HEALTH EFFECTS ASSESSMENT REPORT	December 2016
Table 12a. Summary of EPA Assessments: l,2-Dibromo-3-chloropropane (DBCP)
CASRN 96-12-8
('lii'iii ic;il
(Dale of
rciiulalioni
1 .S. I PA/OW National Prim an Drinking \\ alcr
Regulation (NI'DW R)
I .S. I-'.PA IRIS
I .S. IP A OPP
a
CJ
'	
/ —
7. C
Id
- ?
=P -n-.
= _
- 'd '1 |
-5 = s
=6 S. O o
o ^ ^
5	O a 8=
w _ -O UJ
G ¦ Lu ^
6	£ => ^
.2 o 5
5 :s •= 5 5 8. "S
y. — — — ^ — ^
J ^ = S 2
^ £
O = -3 i ^ -
'J. -j 'J " —
- > - J
0 w " <2
JI
- ¦/
-J *
UJ
>
!l ^ o |
ii«
—		 •— s ¦ J
—	•_ .. 73
r: C_ *j __
^ '¦> ~ _
'— -*• — ~z. J
C£ U-
—
2 o 'j 5
¦¦= "2 = 5 o £. -3
y. — — — — — ^
H z 7 ^
i - 5 v 3 _ =
O = -3 i -
J. -j 'J " ±
- > - J
w - -
_ s
12 = 13
CD.= 73 > ^
s-S b
— ¦_ S.J
= 1 I p b
_
2 o 5
E 32 -H 5 S 8. "3
i/i - 2 ^ J „ o
i H z
" ° S a s
O b <£ ^ ^
'A o o * 2
= > - J
0 w " <5
l.2-Dihi\>nin-'-
dilnmpiiipaiic
(DliCI'i (iwlui
0
0 odd:
(KM..

152. Probable hiiiiian
carciimucii (ll>N<>i
uuideliiies)
I'ulcncv: 1 4 per
iim ku da>.
Driiikiim \\;ilcr
cuiieeiiiralimi al Id
riskle\el () 00025
in- 1. (I3\V)2 ^
l.ineari/ed
iiiuliisiaue model





85
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Six-Year Review 3	SUMMARY HEALTH EFFECTS ASSESSMENT REPORT	December 2016
Table 12b. Summary of Assessments by Other Organizations: l,2-Dibromo-3-chloropropane (DBCP) CASRN 96-12-8
( homiciil
ATSDR
( ;ih:p\
WHO
Includes J IK T'A.
JMPU. CICAI). I.IK
lkal(h Canada
N AS
(jwir)
IARC
(j win
MI.IIS
(> win
o£ =0 p.
^ cp ^
CJj C3
= o
**.
= -
O
*—
'J rz H
J r:
5 G o
¦" s.
CjO
£ ^
i-5C
w cfi ~
X> " JS °
g 2 EP w
"5 — ~
E—
.o
5 0 i
= o
y «" ¦
w y. —
~
-	o c. —
—	X) ~
•= a. = o
x- o -j w
^ da " "
^ ^
o ^
	
o - ¦_
-> r:
S G o
¦" ~.
•W /
1.2-Dihrnmn-'-
dikimpi'upaiic
(DliCI'i









keasnnahls
aiiliapaloJ In
he a hiiiiiaii
caivmnucii
(2014)
86
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Six-Year Review 3
SUMMARY HEALTH EFFECTS ASSESSMENT REPORT
Table 13a. Summary of EPA Assessments: 1,1-Dichloroethylene CASRN 75-35-4
December 2016
( homiciil
(Diilo of
rciiiilalioni
I .S. I.PA/OW National Priman Drill kill" Walcr
Rciiiilalion (\PI)\\ K)
I .S. IP A IRIS
I .S. I.PA OPP
CJ
'	
~ —
7 C
Id
- ^
=P -n-.
= _
cj 2
?
's r. O
^ <- •¦=
_ — - H
'-± = W
52 oi
=o b -a y.
S. "C3
£ Uj
— '— s.
G ° ^
2 o o z
1 "o ~ = -z:
^|it |2
" *3 -5" 5 uj i
M -Pj 7 '5
= . J '¦ ~
7Z y- = o —
— '¦ ¦—
w / —
CJ
s.
—
UJ
>
c.
= —
o -' o
r r= 2 1
Tl = £ ~
5 a. o
Ifo ^ £
CD t— p UJ
s-e^
G •§ 3
2 O O i j
.1 ~ — = -r
||lt ||
^ *3 -5" 5 uj i
n s- - 'J £
— '• ¦—
—
= —
o — 2
¦ 'j —
	 — w/ ¦
E ~ w
3-f EL o -
Jail
y Uj
G '5 3
^ _
1 o O i r
li — ~ =
^ *3 -5" § uj i
- J j s —
T. S~ ~ 'J
— -/¦
w / —
l.l-
l)idikn\>clh\ Icnc
ilWii
		
o (Ill-
O.Ol III
 (falls
channel Quasi
el al . I'iSi
( . Possible human
caicuio-jcn (1 liS(>i
uuidclincsi
o '5
2o"., (also a
factorof In lor
class ( .
possible
carcuioucui
0.05 (2002(1)""'/
4.(. (BMl)l.m)/
100 (ION.
1 OA)/1 ,i\ or
lo\ici(\ (l';il(\
change)/ Quasi
ol ill.. I'>S3
'Simucsii\c
c\ idcucc" of
carciuoucincil> hm
llOl sufficient
c\ idcucc In assess
human carcuioucuic
potential under dial!
I'WJ (.iiidelines
(I S i:i>\. :i)()2d)


46 Using the RfD of 0.05 mg/kg/day and assuming 70 kg body weight, 2 L/day water consumption, and a 20% RSC, a potential new MCLG derived from this
value would be 0.35 mg/L (rounded to 0.4 mg/L).
87
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Six-Year Review 3
SUMMARY HEALTH EFFECTS ASSESSMENT REPORT
Table 14a. Summary of EPA Assessments: cis- 1,2-dichloroethylene CASRN 156-59-2
December 2016
( hemiciil
(l)iilo of
ivuuliilioii)
I .S. I.PA/OW Niiiioiiiil Priniiin Drinking \\ ;ilcr
Rciiuliilion (\PI)\\ K)
I .S. I-'.PA IRIS
I .S. I-'.PA OPP
U
CJ
'	
/. —
"7
Id
=P -R-
= _
w /-
- -d £
flic
t°ls
= u
G •= D_
o£ <£ 3
S o '-> o
y. — — — — —
C/5 Zr, ~ — — £ —
7" t— = $ - 7. o
J - r * 3 - =
o b ^ •£. ^ ^
A -j ±
- > - J
w - -
l)\VI!l. mm 1. i tV;
use
11 = ll
cX) • — ^ O
S-o u
— — 	c ¦
£ S. p uj
'¦> ¦> =¦ _
'— J
2S ~
2 o ¦-> o
S2'i 5 y Q. •a
*• — — — — —
C/5 — — — iZ JZ
-H — ~ 7j
¦t - /J3- =
o b S ^
y o o "
= > - J
w ~ -
|| fefl
CJ) .= >5 > ^
z* d -z
«^ = -§ O
C3 Q. p hj
/-V O O - —
Cr —
c£ u.
—
2 o o s
S ^ 5 y EL •a
 - J
0 w " <2
c7.s-1.2-
Didilnmclhv lone
(IWIU)
mi"
()()-
uoi
(\o\i:i.i
^O	loll.
II) V |0|„
'1)1
decreases in
hematocrit
\lc( aiiles el
al. iwo'

o ^5
:o"„
0.002
(20I0I))4"/ 5.1
(liMI)l.ln)/
		(Kill.
I0A. I0S.3I))/
InciViiscd
ivl;ili\c
kidiK'.v neigh I
in in;ilos/
Mc(';iuk'\ el
ill.. I«)90.'l«)«)5
Inadequate
iiil'ormalkiii in
assess ihe
carcninueiiic
potential <2oo5a
uuideliiies. 20lohi


47 The potential new MCLG could decrease based on the RfD from 2010b IRIS. The RfD is 0.002 mg/kg-d and assuming 70 kg body weight and 2 liters water
intake per day, the DWEL would be 0.0595 mg/L. Using an RSC of 20% the potential new MCLG would be 0.01 mg/L.
88
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Six-Year Review 3
SUMMARY HEALTH EFFECTS ASSESSMENT REPORT
Table 15a. Summary of EPA Assessments: fra«s-l,2-Dichloroethylene CASRN 156-60-5
December 2016
( hemiciil
(l)iilo of
ivuuliilioii)
I .S. I.PA/OW National Prima r\ Drinking
Wsilcr Rciiiilalion (\PI)\\ K)
l .S. I.PA IRIS
I .S. IP A OPP
C
CJ
C—
/. —
7 C
Id
=P
= _
CJ 2
/
z = ~- '=¦
| S ;
so n. o O
o T3 'i
is a
s  UJ
6 | ii. ^
S. ^ ^
2 o '-> z.
'¦= "2 = 5 5 ±~3
y. — — — — —
C/5 — — — £ —
¦7; <— 5. « — * o
J - r 1. 3 - =
o b ^ ^ ^
'J. -j 'j " ±
- > - J
w - -
>cj
_ -
UJ
>
cJ) • — ^ O
=0 5 ~o o
— _ —
° S a. p uj
~ -J o - _
Q c/i
0£ U>
S o
S % ¦= 5 y EL "3
(/} Z ^ — o
c/j — — C —
-H — E. — ~ ^
¦t r i. 3 - =
o b ^ ^ ^
J. -j 'j " ±
- > - J
0 — " <5
||S°|
OX) ^
=¦§ o
c: a. p m
^ -J o - —
— -r i
_
± -j o
S2I 5 y S. •a
Z ^ — O
1/5 ^r» -= ?r — ^ —
^ ^ C/5 f/5
^ I
2 ^ — 2
= > - j
w - -
trans-1.2-
l)idikn\>clh\ lone
ilwlm
I) 1
I) 1
no: i~<\<).\i:i.)
1	(ION. 10 \.
1 oS> Males
increases in serum
alkaline
phusphalase.
females decrease
in rclali\c ih\ inns
weiulil IJaruesel
al . I'«5
1). \oi classiliable
as in human
carciuoucuicin
(1 lJX ¦ (.5
(I:\idi. ) 			
( |0||. |(l \. |()S.
"I)i Decrease mi I lie
number of aniibods
forumm cells
( \l '( s) auaiusi
sheep red blood
cells (skiH i mi
male mice Shoppel
al . I'«5
luadei|iiale
iiirormaliou lo
assess ilie
carcinogenic
poleuiial (:oo5a
uiudelilies. :olobi


48 IRIS completed an assessment in 2010; however, the new RfD does not result in a change to the MCLG.
89
-------
Six-Year Review 3
SUMMARY HEALTH EFFECTS ASSESSMENT REPORT
December 2016
Table 16a. Summary of EPA Assessments: Di(2-ethylhexyl) adipate (DEHA) CASRN 103-23-1
( lu'inical
(Diilool'
roiiulalion)
I .S. I-'.PA/OW National Priman Drinking \\ ;iier
Re»iil;i(i»n (\PI)\\R)
I .S. I-'.PA IRIS
I .S. I-'.PA OPP
CJj
 o
^ '3 o § EL
rr _1 E_ ' —
¦> ~ ~ 'j — • —
•w' 	
iS,
CJj r ,
?
3 S
"V*
P " ° _Q ^
fy*1 ^
~ f —
± o ¦> s
O y o "P
*7* H. $ £ * o
¦> ~ ~ 'j — • =
	
Q ^ Q .1 >-
~ /. —
' 7 E 5 - — "o
•ft <— H. $ — * o
o o cr o fTi ^
	
1 )i< 2-
ellix IIie\> I)
adipale
il)i:il \i
(l'W2h)
04
1)4
()(¦ l"()
(\o\i:i.i ^00
( 11)11. Ida.
and 1)
en n ih ii ied) IJodv
and lixer uemlil
eliaimes in
paivnis. red need
ossiliealion and
slmlilK dilaled
iiieleis mi
leliises. reduced
ofl'spinm wemlil
uain. loial liller
wemlil. and liller
si/e ICI.
I'JXXa.h
(Kissihle hiiniaii
carcinogen (1 vxi
uuitlelilies. I'Wle)
I'oiencv" 1 2 lo
per inu ku da\:
Drinkiiiu waler
coiicciiiralion al lo
risk lex el ' lo
mu 1. (I5\V)2 "
l.iiicari/cd
milllisiaue model


90
-------
Six-Year Review 3
SUMMARY HEALTH EFFECTS ASSESSMENT REPORT
Table 17a. Summary of EPA Assessments: Dinoseb CASRN 88-85-7
December 2016
( homiciil
(D.ilc ol'
ivuiiliilioni
(l.isl A or B)
I .S. I.PA/OW National Prim an Drinkinii \\ akr
Riliulalion (\PI)\\ K)
I .S. I-'. PA IRIS
I .S. I-'. PA OPP
U
CJ
'	
/. —
7 w
It
_ ^
=P -n-.
= _
w --
- o £
file
fSlg
G •= u_
& £ => ^
2 o -j z.
'¦= "2 = 5 i. ~3
— — — — —
tS) JZ
7" t— H. " - 7 o
¦t r i ¦=¦ - =
O = -3 i. ^ -
'J. -j 'J " ±
- > - J
0 ~ " <2
DWI !l. mm l.i A:
kSC
cX) • — ^ O
S-o [j
— — ¦_ 	^ ¦_
c3 a. p uj
'¦> ¦> =¦ _
'— J
~
_
2 o ¦-> o
S2'i 5 y Q. •a
y. — — — — —
C/5 — — — S2 —
-H — i- ~
¦t - /J3- =
o b S ^
y o o "
= > - J
w ~ -
|| fefl
CJ) .= >5 > O
z* d -z
£ ^ *¦" ^
C3 Q. p hj
/-V 'J 'J •— —
Cr — ~
cC u.
—
2 o o s
S ^ •= 5 y S.
t/i s ^ ^
c/i — — S2 —
-H ¦— E. *¦ - ~ o
J - r 3 - =
o b 9" £ ^ ^
'J -j 'j " —
= > - J
0 ^ " <2
Diiinseh (l'W2h)
		
()()()-
oool I
 perplasia and
li\ puspcrmalo-
ucncsis.
lesiicular
dcuciicralimi
1 la/lclmi. I'J .
IJmun. I'JSI
1). \m classifiable
as i« Iiiiman
caiviiinueiiii.il>
i I'JXih »iiidolilies)
(1.(14
:o"„
0	001 (l'JS(.d)
1	(i.o\i:i.i
11)1)1)1 loll.
10 \. lol.l
Decreased pup
uemlil durum
laclalinu
pcrmd
1 )ecreased
parenlal
wemlii uain
l)mx Chemical
(unipam.
I'JXI
I). Nm classiliable
as ik human
carciiinueiiicilv
(l'JS(n uuidelilies.
IWVI


91
-------
Six-Year Review 3
SUMMARY HEALTH EFFECTS ASSESSMENT REPORT
Table 18a. Summary of EPA Assessments: Dioxin (2,3,7,8-TCDD) CASRN 1746-01-6
December 2016
( homiciil
(l);ili- ol'
roiiiilalioni
I .S. i:i» \/()\\ National Prima r\ Drinking Wiilcr
Rciiiilalion (NI'DW K)
I .S. I-'. PA IRIS
I .S. IP A OPP
~5p
CJ
'	
/ —
I
Id
_ ^
op -ft.
= —
w --
- 'd '-= £
n. o ^
- 7= :¦>
s 'o a £
w Z. •£> uj
9 •= u. 'w
£ => ^
2 o s
Ss = 5 y Q.•a
(/) — S Z ^ ®
(/) — — £ —
-H — =. '¦ - ~ o
J - r * 3 - =
o b ^
J. -j 'j " —
- > - J
w - -
3 S-
_ -
UJ
>
tl = ll
CD • — ^ O
= -a y
— _ —
0 S. p uj
^ -j 0 - _
'— — n; y
0£ Ll.
_
2 0
¦= "2 = 5 y ~c-~5
y. — — — — —
C/3 Zr, ~ — — £ —
¦7; <— 5. $ " 7 0
¦t r ^ -3 - =
i. ^ ~
j. -j 'j " ±
- > - j
0 ~ " <2
|| ^ f |
CX) ^
= ¦§ 0
— — — s.J
c: a. p m
^ -J 0 -
Qi D_
_
2 0 'j s
5S-= S y n. -a
Z ^ — O
S —
™ ^ /. / — ™
.'J ^ jy 5- =
-J- L "J
0 ~ " <2
K 1)1)
(1 )k>\lll I
( l')SSI")
0
^ |o"
(KM.)
1 ID 1 ID
 el
al . I
152. I'rnhahle
hiinian carciiinueii
(l')S(ii unidelilies>
l\>lenc> l5(>.ooo
per nm ku da>.
Drinknm waler
cuiiceiiiralimi al Id
risk lex el" 2 Id
iiiu 1. (I5\V)2 ^
l.iiiean/ed
ninliisiaue model
'5 ID"
" ID (2D|2h)
2 ID" ;or,ii.
1 d |. 1 decreased
sperm cniini and
iiKiiiliix 111 men
exposed In K 1)1)
ashuvs Mncarelli
el al . 2dds
Increased 1 SI 1 111
neonates
Haccarelli el al .
2D0X



92
-------
Six-Year Review 3
SUMMARY HEALTH EFFECTS ASSESSMENT REPORT
December 2016
Table 18b. Summary of Assessments by Other Organizations: Dioxin (2,3,7,8-TCDD)
CASRN 1746-01-6
( homiciil
ATSDK
( ;ih:p \
WHO
Includes .ll ( I- A.
JMPU. ('I('AI).
I.IK
llciillh ('iiiiiidii
Y\S
(\c;ir)
IAUC
(\c;ir)
/. —
= z
^ c
/ -
ai. =o «
S ^ "
op ^
5
CJj
~ —
CJj C3
'J ~ ¦_
-> '¦> 71
5 S °
M ' w-*
w isi
~
»•».
£ 5 s-
E- 5 ~
.2 ~ =0 v=
'¦> -*¦ J
^ -£. **•
g 5 zP w
~z. — ~
H
2
5 5 i
E
O C/}
~
— os —
™ ^
•E a. c ^ o
/ > O w
W -
s
s—
o - ¦_
-> r:
E ¦-=
•" ~. ^ •
w (/}
v'.s-

4 " lo
l.ikeh In he
~
~
—
—
—
(unup 1.
Know ii in
ix Di)


cai'ciiinueuic





(aiciiinueuic
he a human
(l)in\uii

< 2o loci >
lo humans





lo humans
eaieiunueii
( I'JXXI")


i:o|odi





i:oi:hi
<:o|4i
49 The public health goal derived by CalEPA is based on cancer potency. The RfD-equivalent shown was calculated based on the NOAEL and UF provided by
CalEPA for noncancer effects.
93
-------
Six-Year Review 3
SUMMARY HEALTH EFFECTS ASSESSMENT REPORT
Table 19a. Summary of EPA Assessments: Diquat CASRN 85-00-7
December 2016
( Ik-iii ic;il
(l);Mc ill"
rciiiilalinni
I .S. I PA/OW National Priniiin Drinking \\ ;ilcr
Roiiiilalion (NPDW K)
I .S. I-'.I'A IRIS
I .S. I-'.PA ()l»l»
U
CJ
'	
/. —
7 C
Id
_ ^
=P -w-
= _
- o £
-3 = S
on a. o °
^ a T3 ^
= O ^ £
w Z, -£> uj
G •= u_
* S. ^ ^
2 o '-> o
y. — — — — —
C/5 Zr, ~ C — C —
7" <— pL  - 7. o
J - r * 3- =
o b ^ ^
J -j 'j " ^
= > - J
w - -
l)\\ l!l. mm 1. i tV;
RSC
f |S||
cd • — ^ O
E -a o
^ ^ ^ c;
^ c5 S. p uj
<¦* -j o - _
*— ^ — J
CC Ll.
2 o ¦-> o
£ :§ •= 5 y EL •a
c/j Z ^ -?* O
 ;^r — — ~ c —
-7; t_ =L " — 7. 0
¦t r ^ 3 - =
0 b 9- <2 ^ ^
y 0 0 ¦' ±
- > - J
w - -
|| S11
CD > O
«^ = -§ 0
— ___ •_ S.J
r: a. p m
^ 0 0 -
c — ~ '¦
0£ U.
_
2 0 ¦¦> c
S :S -2 5 y E.-a
y. — — — — —
 ^ S — S2
^ ^ c/j
.'J ^ f'/5- =
2 in — 2
= > - J
O ^ <2
l)it|ii;il ( l'W2h)
no:
o u:
o oo: o::
<\o\i:i.i
|U()( |()||.
IDA)
Calaracls
Cullev. 1
1). \m classifiable
as u< human
carciiinueiiicilv
(1h mndeliiies)
on—
:i)"„
ooo::
i i'JS(.ci ii
(\o\i:i.i loo
( loll. |0 \)
Mimnial lens
upacilv and
calaracls
(Chc\ mil
Chemical.
11>X5

0.005 (l'W5ii.
2002c)-5"/ 0.5
(NOAI'.I.)/ 100
(ION.
I0A )/ciiliii'iicls
in Icniiilcs.
ricereused
adrenal and
cpi(li(l> mis
n eights in
niiilcs/
Hopkins. 1 *>*>()
1!. 1 ideuce nl'
iKiiicai'ciiKiueuicil>
i I'JSiii miideliues.
|w5hi
50 The MCLG could increase based on the RfD from OPP 1995a and 2002e. The RfD is 0.005 mg/kg-d and assuming 70 kg body weight and 2 liters water intake
per day, the DWEL would be 0.175 mg/L. Using an RSC of 20% the potential new MCLG would be 0.04 mg/L.
94
-------
Six-Year Review 3
SUMMARY HEALTH EFFECTS ASSESSMENT REPORT
Table 20a. Summary of EPA Assessments: Endothall CASRN 145-73-3
December 2016
( hcmiciil
(l)iilc of
rc'liiiliUion)
(l.isl A or li)
I .S. I'.PA/OW Niiiioiiiil Priniiin Drinking
Wsilcr Riiiiihuion (\PI)\\ K)
l .S. I-'.PA IRIS
I .S. I-'.PA OPP
U
CJ
'	
/ —
/ w
iz
- /
2P -n-.
= _
CJ 2
/
>1 o|
flic
t°ls
-fiui
G •= u_ ^
al £ ^ ^
2 o z.
Sl-= 5 y E. V,
c/) — s Z ^ O
C/5 ~ — — C —
-H — =. ' - ~ o
- ^ y 3— =
— i. ^ ~
-j 'j " ±
- > - j
w - -
>cj
_ -
UJ
>
si
#•5 a
=0^- d T3 o
— 	 •_ s ¦ J
c S S. p u
^ ¦> =¦ _
'— — "ZT J
cC tu
_
2 o ¦->
Ssl 5 y EL •a
y. — — — — —
C/5 _ — — S2 —
-H ¦— =. £ - ~ o
J - r y 3 - =
o b S2 a ^
y o o "
= > - J
w - -
|| fefl
CD .= >5 > ^
«^ = -§ O
c: Q. p m
-j -> -
IX
S y '->
S ^ 5 y EL "2
c/) — — S2 —
-K — =. £ - ~ o
J - r ^ 3 - =
o b 9" •£. 2 ^
y o 'j " —
= > - j
0 ^ " <2
1 Jidnihall (l'W2hi
0 1
U I
u <>: :
(\o\i:i.)
1 Mill Kill.
in \i
1 lie ivased
nruau ucmhl
and nruaii-in-
hud\ uemhls
I'm' sinniach
and small
uiiesiiue
Keller. I'Ko
1). \nl elassiliable
as iii human
carciuimcuicil>
(1 'JXiii uiiideliiiesi
II."
:
(\Oi:i.i luii
( Kill, in \>
Increased
ahsnluie and
relume uemhls
nrsinniach and
small uiiesiiue
Keller. I'Ko

(MMC
(2005(1511/2
(I.OAI.I.)/
		ION.
I0A. 31.)/
Pr(»lircr;ili\c
lesions of (lie
5i;islrie
epil helium/
Trul (er.
I nlikcK In he
carcinnuenic In
humans (I'J'J'J
uuidelilies. 2no5di
51 Using the RfD of 0.007 mg/kg/day and assuming 70 kg body weight, 2 L/day water consumption, and a 20% RSC, a potential new MCLG derived from this
value is 0.049 mg/L (rounded to 0.05 mg/L).
95
-------
Six-Year Review 3	SUMMARY HEALTH EFFECTS ASSESSMENT REPORT	December 2016
Table 20b. Summary of Assessments by Other Organizations: Endothall CASRN 145-73-3
( hcmiciil
ATSDK
( maw
WHO
Includes .ll(l\.
JMPK.CICAI).
i: ik
llciillh ( iiiiiithi
N AS
(jwir)
IARC
(\e;ir)
MI.IIS
(jwiri
-j 5 -n-
ai. =o
CI) w
CJj C3
— 'J
**.
s
'j - ¦-
¦> 71
S G o
C J w
n 5
i-5C
.2 ~ =o ?=
^ .«*.
"s — ~
E—
5 ^ i
= o
. • - j.
O 00 s—'
~
-	o s —
—	X) ~
•= a. = ^ 0
~ O O w
.5 . ^ - "
¦" " ?
o
o r: H
-> r:
5 c o
¦" s.
CjO
1 indolhall

<1.1125
(2*1141








52 The public health goal derived by CalEPA is based on noncancer effects. The RfD-equivalent shown was calculated based on the NOAEL and UF provided by
CalEPA for noncancer effects.
96
-------
Six-Year Review 3
SUMMARY HEALTH EFFECTS ASSESSMENT REPORT
Table 21a. Summary of EPA Assessments: Endrin CASRN 72-20-8
December 2016
( homiciil
(l);ili- of
rciiulalioni
I .S. I.PA/OW National Prim an Drinking \\ alor
Kciiiilalion (\PI)\\ K)
I .S. I PX IRIS
I .S. IPX OPP
CJ
/. —
I S_^
Id
_ ^
-N-.
= _
w --
- -± '-= £
file
tSlg
G •= u.
S. ^ ^
2 y ¦->
S S -2 5 y EL ^
y. — — — — —
c/j _ — — £2 —
-H — ~ 0
.j - r y s- =
O = -3 ^ ^ -
J. -j 'J " ±
- > - J
w - -
>CJ
3 S-
_ -
UJ
>
flMl
CD • — ^ O
S S". «
S-o u
— — •— s ¦ J
a. p uj
0 0 - _
'— — n; '¦
0£ U>
_
2 y -j z.
S :S •= 5 y EL •a
y. — — — — —
C/) ;^r ~ — — C —
-K ~ ^
J - r ^ 3 - =
0 b 9" £ ^ ^
y 0 *-> " ^
= > ^ -j
0 ~ " <2
|| ^ 11
CX) ^
Z, d Z
= -§ u
— — •— '¦ ->
w C3 O. p rjJ
/-V O O - —
C- — '¦
oC U-
—
2 0 0 0
sl'i 5 y EL •a
y — — — — —
C/5 ~ — — S2 —
7- t_ =L S/> — T< 0
J - r i. =¦ - =
0 b 9" £ * ^
y 0 0 " ^
= > £ J
0 ^ " <2
1 iiiclriii (
o uo:
o on:
O 00(1 i 00:5
(\<>\i:i.i 100
(loll. IDA) Mild
liisinpaiMnuic
chaimcs 1111 in or.
nccasumal
cum iiIskhis
Yelsicul Chemical
( nipnialinii. I'M
1). \m classifiable
as u< liiiniaii
caiviiinuenii.il>
(11>S(h mndcliiicsi
0 00';
:o"„
			 11 wssu)
nn:5(\o\i:i.i
inn i loll, in \i
Mild
hisiopalholnmc
chaimcs 111 li\cr.
occasional
chii\ iilsiHiis
Yelsicul Chemical
( HipHialiHii. I'M
1). \m classifiable
as ik liiiniaii
carciiinueiiicilv
( I'JXih miidcliiics.
I'JXXm


97
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Six-Year Review 3	SUMMARY HEALTH EFFECTS ASSESSMENT REPORT	December 2016
Table 22a. Summary of EPA Assessments: Ethylene dibromide (EDB; 1,2-Dibromoethane)
CASRN 106-93-4
( homiciil
(l);ili- ol'
iviiiilalinn i
I .S. I-.I'A/OW National Prima r\ Drinking
\\;Kcr Riiiiilalion (\PI)\\U)
I .S. I-'. PA IRIS
1 .S. IP A OPP
"cp
CJ
'	
/. —
7 C
Id
- ^
-n-.
= _
CJ 2
Z =¦
|s ; =
m a. o
O ^
>;
5	o a i=
¦— ^
G ¦ Lu 'Trt
6	£ ^ ^
.2 o ¦-> Z
'¦= "5 = 5 8. "3
y. — — — ^ — ^
H z 7 ^
i - r y. -3 - =
¦J ¦- -2 £ ?. ¦-
'J -j 'J " —
- > - J
w - -
3
- ¦/
_ -
UJ
>
Il = ll
11 a
~ C3
_ 77 O 1_
<¦* -j 'j — _
'— — ~Z. '
0i Ll.
2 o ¦-> 3
'¦= "5 = 5 8. "3
y. — — — — — ^
h. ~± Z 5
i - J V 3 - =
¦J =. => Z Z ¦-
'J. -j "J " ^
= > - J
O w " <2
_ s
12 = 13
CD.= 73 > ^
— ¦_ S.J
2 - " - 2
2 o ¦-> 5
5 ^ 5 5 EL
y. — — — — — ^
H Z 7 ^
^ - r v 3 _ =
-J = -3 i ^
^ o o ' 2
= > - J
0 ~ " <2
1 !ili\ leiie Dihromide
.
Driiikiuu ualer
coiiceiiiraliou al In
risk le\el 2 In
nm 1. ilJWi' 4
I.I! 1 > 1 o Willi linear
eMiapolaliou. slope
factors calculaled
from niuliiple iiinior
siies and suninied
iisiuu sialislicall>
appropriale model.


53 The current NPDWR assessment is not consistent with the 2004 IRIS assessment. The PQL is slightly greater than the 1 x 10~6 risk concentration of 2 x 10~3
mg/L.
98
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Six-Year Review 3	SUMMARY HEALTH EFFECTS ASSESSMENT REPORT	December 2016
Table 22b. Summary of Assessments by Other Organizations: Ethylene dibromide (EDB; 1,2-Dibromoethane) CASRN 106-93-
4
( homiciil
ATSDK
< iiir.PA
WHO
Includes .MKT"A.
JMPU. ('I('AI). I IK
Ik-allli Canada
N AS
(\e;ir)
w Z
11
S. —
= =
^ £
/ -
.
ai. =o p.
2 ^
op w
5
OQ
s 	
CJj C3
**.
= ~
2^
— ~
O - ¦_
-> '¦> 71
= O
•" I
•w /,
E— 5 ^
ii W =0 5=
o o ^ 9
r 3 ~
~z, — ~
H
.5
5 5 =
E "J
s. .
O (/> N—^
w
— O C. —
™ X) v-v
= c. = ^3
~ > O W
» d ^ ^ -
^ ^ o ?
O ^
s
~
o - ¦_
-> r:
= '-= °
•" y. ^ •
' /.
1 !ih\ lone dihmmitlc
-------
Six-Year Review 3	SUMMARY HEALTH EFFECTS ASSESSMENT REPORT	December 2016
Table 23a. Summary of EPA Assessments: Fluoride CASRN 7782-41-4
('homic;il
(l);ili- of
ivuuliilion)
I .S. I-'.PA/OW Niilioiiiil Priniiin Drinkinii \\ ;Ker
Roiiukilinn (\PI)\\ K)
I .S. I-'.PA IRIS
I .S. I-'.PA ()\\
~5p
CJ
'	
/. —
7 w
Ic
_ ^
=P -n-.
= _
w --
- o ¦£
| H J
^ O ^3 ^
IS 8
S <3 a 8=
w Z. uj
G •= D_ -S-
^
2 o '¦> o
5s-= 5 y EL•a
(/) Z ^ — O
(/} Zr, ~ — — 12 —
C3 ^ ^ (/> 7/> — —
¦t~- r > i- =
2 5 <3 — 2
= > - J
C w " <2
3
_ -
UJ
>
11 = 13
cd • — ^ O
z, d c ^
5 -o o
0 c3 a. p uj
^ '-> ¦> ir _
'— y
cC u.
2 y ¦-> c.
S ^ ¦=. 5 § EL "2
y. — — — — —
c/) ;^r — — £2 —
t; <— " s * "
J - r i. =¦ - =
o b ^ J2 ^ ^
y -j 'j "
- > - J
0 — <5
|| fell
CD.= ^
Z, d Z
= ¦§ o
— — •— ' ¦ ->
—
r: — ¦ ¦
-j o -
VC U.
_
2 y ¦-> s
sll 5 y a. •a
c/j — s — ^ O
c/j ^ ~ — — £2 —
-?¦ <— 5. « - 7 o
J - r ^ 3 - =
¦j - — i. ^ ~
'j -j ^ ±
- > - j
0 ~ " <2
Fluoride
i l'JS(.k)
4o
4o
\nkll) 2o iim da>
(I.O\i:i.iC 5111
cnppliuu skeletal
fluorosis Shapiro
I'Kv kiuip l'JS4.
who i«js4

1 00" ii
O 0(i
l'JS(.»
oo(,(\o\i:i.i
	
ohjeeliouahle denial
IlllOIOSIs
Undue 1 *J5<>

DOS (2010)
o o" iniake
from diiiikiiiu
ualer oo|
iniake lie in
food i III
Se\ ere denial
IlllOI'OSIS III
eliildreu
Dean llU2
\le( lure
\1>V-

54	EPA published a secondary maximum contaminant level (SMCL) for fluoride of 2.0 mg/L to protect against dental fluorosis (an adverse cosmetic effect)
(NPDWR for fluoride, April 2, 1986 (51FR: 11397)).
55	The IRIS Substance Assessment Tracking system website (https://cfpub.epa. gov/ncea/iris2/atoz.cfm) should be consulted for the most current information on
the status of this assessment.
100
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Six-Year Review 3
SUMMARY HEALTH EFFECTS ASSESSMENT REPORT
Table 24a. Summary of EPA Assessments: Heptachlor CASRN 76-44-8
December 2016

I .S. I.PA/OW National Prima r\ Drinking Wali'i1
Regulation (\PI)\\ R)
1 .S.
I'.PA IRIS
I .S. IP A OPP
ClK-miciil
(Diilo of
iviiuhKioin
CD
S*
/. —
s_ O
o
— z'
CJj •%.
1
CJ 2
s*
"3 = ? .=
^ n 2 ^
|§!|
e—v ~ —
ry* O 1—S [j__
7 /. —
^ O ¦> S
^ ^ O 5 EL
•r: <— =L $ — * o
o 0 cr o r t i ^
qrv
•w' 	
iS
CJj r ,
3 S
<>/
s
« 1 "g 1 §
^ >, H 2 £
P " ° _Q ^
fy' N*~"' N*~^ [jLa
I ^ o I
•T- t— 5L " " 7 O
-> - ~ 'J — ¦ ¦ ~
W 	
@ " q i
7 / . —
± O ¦> S
^ ^ O 5 CL
C- H. $ — * o
¦> - ~ y — _ _ —
.= 51 " " i.
•w' 	
1 lepiachlor
0
o 0004
() 0005 0 15
132. hohahlc hiimaii
—
0 0005 ( I'JST)
IP. Probable human
0.0005 1l'W2ci
152. Probable hiimaii
(I'^lm

tl'ni.i
(\o\i:i.i 'oo
carcinogen (1 'Mm

o 15 i\o \i:i.i
carcinogen 11 'JSiii
o 15 (\<> \i:i.i
carciiiouen 11 lJS(ii



(loll, lo \. ^))
•nuclei nies)

'00 ( lol l. lo \.
uniclehlies.
'00 ( |o| 1. |o \.
uniclelilies. Iiw2ci



Increased 1 in cr In
Poiencv 4.5 per

'I)i Increased
Poiencv 4 5 per
'I)) l.i\er




hods weiulil ralio in
iiiu ku da\.

li\ er iii hods
nm ku das. Drmkiim
lesions and




males Wuhcriip el
1 )rnikiim waler

weiulil ralio in
\xaler concern ralion
increased




al . I<>55
coiiceiiiralion al lo
risk le\el" S lo
inii 1. ii:\V)2 '
l.iiieari/ed
miillisiaue model

males Yelsicol
Chemical. 1^55
al In risk lc\el
S lo
nm 1. (IJ\V)2 ^
l.nieari/ed milliisiaue
model
relalne li\cr
weiulil
Wilhernp el al .
1^55

101
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Six-Year Review 3
SUMMARY HEALTH EFFECTS ASSESSMENT REPORT
Table 25a. Summary of EPA Assessments: Heptachlor epoxide CASRN 1024-57-3
December 2016

I .S. I.PA/OW National Prim an Drinking
Wain- Kouulalioii (\PI)\\R)
1 .S.
l-'.PA IRIS
I .S
IP A OPP

( hemiciil
(l)iilo of
rciiiilalioni
CJj
/. 	
Z
— -w'
— 7
CJj
•\
CJ 2
EL S ^
|ep
s ~ ~~
O —\
~ f —
± o ¦> s
^ ^ *3 o 5 EL
•ri ™ o
-> ~ 'j — • • —
»!4T
O w' -
CJj . .
3 y
s
«•! -§ I §
g3^ |||
2 o 7 j: ~
~ /. —
. ± o ¦> z>
^ 3 $ ^ O
¦> ~ ~ 'J • —
111^1"
Q 3 o is >•
r /. , —
.2 o P o
^ o § EL
'¦> 3" 'j E ^
111^"1
"o
1 lepiachlur
0
o 0002
I) ()()()() 11
152. Probable human
—
0 0000| 1
132. Probable hiinian
0 0000 Ii
152. I'rohahle limn;
111
1 IpoMilc ( I'J'Hu)

(I'ni.i
o 0125
carciiinucii (1 *JS(ii

( 1 l^S(i j)
carcmoucii (1 *JS(ii
(l'W2c)
carciiioucn (1 lJS(ii




ii.o \i:i.i
miidchiicsi

0.0125 (I.I:i.i
uniilelines. I'Wm
o o 125
unideliiies. l'W2ci




||)()() (|o| I.
I'ulciicx Ki 1 per

1000 ( |o| I.
Pi)leiic\. l> 1 per
(I.I 1.) looo





lo \. lol.i
iim ku da\:

lo \. |0|.)
iiiu k» da\.
(loll, lo V





Increase in
Driiikniu waler

Increase in
1 )rinkinu waler
lol.)





h\eMn-hnd\
ciiiiceiiiialKin al lo

1 in er-m-hnd\
coiiceniralion al lo
Increase in





uciulil ralm
risklc\cl 4 lo

weiulil ratio
risk lex el 4 lo
1 ix er-u»-hi»d\





1 )im
nm 1. (I3\V)2 ^

l)mx ( heniical
nm 1. (li\\ i2 ^
wemlil ralm





Chemical
l.iiicari/cd

( onipam.
l.ineari/eil
1 )o\\





( onipanv.
niuliisiaue model

1 1>5N
ninliisiaue model
(heniical





1 1>5X




( onipam.
1 M5X


102
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Six-Year Review 3
SUMMARY HEALTH EFFECTS ASSESSMENT REPORT
December 2016
Table 26a. Summary of EPA Assessments: Hexachlorobenzene CASRN 118-74-1
( homiciil
(l);ilc of
rciiiilalion i
I .S. IIP.VOW National Prima r\ Drinking
Wilier Rciiiilalion (\PI)W K)
I .S. I-'. PA IRIS
I .S. I P X OPP
CD
W
S*
/. —
— >w'
— ^
CJj
1
— *.J ~ 2;
EL S
^ Q Tj
/—s ~ ~~
fy*1 O —\
| ^ o 5
*f! ' SL ^ o
-> - ~ 'j — _ _ —
.yrM
CJj , ,
? V
3 S
s
t|||!
P " ° _Q ^
7 /. —
± O ¦> S
^ o 5 EL "§
•ft <— =L — * o
-> - ~ • —
iii^r
	
j| \ 5
g 3
~ f —
72 o § EL
~ H- $ — * o
-> ^ ZT y — _ _ —
= 51"" 1
o N-"' "
1 IcViellloi'ohcil/CllC
(l'W2h)
0
0 00 1
(POl.)
0	000S 0 OS
(\o-\i:i.) loo
(|0||. |0\)
1	lepnlic
ceninlobiihr
basophilic
dllOlllOUCIiesls
\niokl el ;il .
I^S5
152. I'rohahle Iiiimaii
carcinogen (1 lJX per
iiiu ku da\.
1 )rnikiim ualer
coiieeiiiralioii al In
risk le\el. 2 Id
iiiu 1. iliWi: ^
l.iiicari/ed
miiliisiaue model

(1 000S ( I'JXXll)
0	us i\o \i:i.i
loo i mil.
Id\i llepalic
ceiiirilohular
basophilic
chroiiiouciiesis
\riKd i
Slope I'aelor 1 (> per
iiiu ku da\. 1 )rnikiim
ualer coiieeiiiralioii
al ID risk le\el
2 Id muLdiased
on 1!ri11rk. el al.
I'M.) ii:\Vi2 ^
1 .nieari/ed milliisiaue
model

132. I'rohable human
eareiiiouen (1 'J'Jc.
uuitlelilies. 2D0Shi
slope laelor 1 d2 per
iiiu ku-d.
Iiepaloeelliilar
eareniomas in nils
oralis exposed
(I5W)' 4 IIOl
specified
103
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Six-Year Review 3
SUMMARY HEALTH EFFECTS ASSESSMENT REPORT
December 2016
Table 26b. Summary of Assessments by Other Organizations: Hexachlorobenzene
CASRN 118-74-1
( Ih-iii iciil
A 1 SDR
( ;ih:p \
WHO
IiicIikU-s JIX I-A.
.IMPU. CICAI). I.IK
lloiillh (  '*> r:
= G o
¦" s.
H 5 ^
ii ~ =0 ==
x> " ^ °
— ~
E—
o
5 S i
s ^ °
. ¦ - j. ** ¦
O C/l
~
- o c —
•= a. = r" 3
X- o -J >_/
. a - -
" " ?
w -
( ancer
da^silicalion
(>can
1 le\achk)i'i)heii/ene

()()()()()-
(2i»l5i







kcasniiahk aiilicipalal
In he a human
caiviiinueii <2<) 14)
56 The chronic MRL is based on the same critical study, Arnold et al, 1985 that was used by EPA; however different endpoint (peribiliary lymphocytosis and
fibrosis of the liver) was used compared to EPA assessments (Hepatic centrilobular basophilic chromogenesis)
104
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Six-Year Review 3
SUMMARY HEALTH EFFECTS ASSESSMENT REPORT
Table 27a. Summary of EPA Assessments: Hexachlorocyclopentadiene CASRN 77-47-4
December 2016
( homiciil
(Diilc of
ivuuliilion)
I .S. I.PA/OW Niiiioiiiil Priniiin Drinking Wsiicr
Kevinl -i —
S <3 a 8=
w _ X) Uj
G •§ u. 'w
qL ^ ^
2 o 'j s
'¦= "2 = 5 y £."?
y. — — — — —
tS) JZ
¦f; t— H. " — 7. Ti
J - r * 3 - =
O = -3 ± ^ -
y o -J " ^
- s- - '¦>
C ~ " <2
l)\\ l!l. mm I.) cV:
kS(
Is fell
cX) • — ^
c* O " £ —
50^- = -o ti
° C3 S. p UJ
O w- ^
c£ U-
—
2 y ¦->
S ^ 5 y EL •a
/¦ —— •— —
(S) — — S2 —
7" t— H. " - 7 o
J - r ^ 3 - =
o b 9" J2 ^ ^
J -j 'j " ^
= > - J
0 ~ " <2
|| fell
CX) .— > O
^ O 2 £ ---
= ¦§ u
c; 2- p m
^ 'j 'j -
C — s.
u.
—
2 o o s
Ssl 5 y n. •a
y. — — — — —
C/5 — — S2 —
-H •— =. £ - ~ 7j
J r ^ 3 - =
O = -3 i ^ -
y j j 'j " ^
= > - j
w - -
1 Icvicllloi'ocsclo
-pcuiadicnc
< l'w:h)
o 05
o.()5
o.oo- " 14 cull
\<>\i:i.) lono
( loll. |0 \. IDS)
local
iiillammaliou of
I he I'o rcsioniach
and sioniach
lesions Ski. 1 MX 1
1). \oi classifiable
as io human
carcuiouciiicil>
(1 MNiii mudcliucsi
D.'
:o"„
O.OIKi <200l;i)"/
(ISMDl.i..)/
1	Kill. IDA.
3S.3I))/
Chronic
irriCilion of
forcsloniiich
(forcsloniiich
lesions)/ Ahdo
el ill.. 1«>S4
\ol likcl> lo he a
hniuaii carcuioucii
\ la inhalalioii ionic.
I'olcuiial lor
cai'ciiioucuicil> In
llic oral mule is
indeterminate hascd
on a lack of data
(liw<. uuidcl iiics i
i:oo|;n


57 Using the RfD of 0.006 mg/kg/day and assuming 70 kg body weight, 2 L/day water consumption, and a 20% RSC, a potential new MCLG derived from this
value is 0.042 mg/L (rounded to 0.04 mg/L).
105
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Six-Year Review 3
SUMMARY HEALTH EFFECTS ASSESSMENT REPORT
December 2016
Table 27b. Summary of Assessments by Other Organizations: Hexachlorocyclopentadiene
CASRN 77-47-4
( homiciil
ATSDR
( ;ih:p\
WHO
Includes .11(1 A.
JMPK.CICAI). I.IK
Ik-iilih ( iiiiiidii
N AS
(\ c;ir)
1 ARC
(jwir)
MI.IIS
(jwir)
£p o
— **.
—
"cij
CJj C3
— 'J
**.
s
	
o - ¦_
-> r:
= G o
¦" s.
on
1-5^
ii w =0 ==
~ »-*.
"s — ~
H
2
5 5 i
S °
O C/l
~
- o o
5 x> -5 SP ^
•= a. = ^ 0
^ :-> -j >_<
¦ a - "
O w
•_ ~
o - ¦_
-> r:
5 G o
¦" ~.
1 lc\adilni\ic>dn|X'iiiadiciic

0 0011
(2014) ¦








58 The public health goal derived by CalEPA was calculated based on the NOAEL from Abdo, et al. 1984 for noncancer effects. The CalEPA assessment is more
current than the IRIS assessment and uses an updated benchmark modeling approach to derive a different POD. However, CalEPA applied policies that differ
from those of the EPA Office of Water so the 2001a IRIS RfD is preferred.
106
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Six-Year Review 3	SUMMARY HEALTH EFFECTS ASSESSMENT REPORT	December 2016
Table 28a. Summary of EPA Assessments: Lindane (gamma-Hexachlorocyclohexane)
CASRN 58-89-9

I .S. I.PA/OW Niilioiiiil Prim;in Drinking Wsiicr

I .S. I-'.PA IRIS
1 .S. IP A OPP



Kouuliilion (\PI)\\ R)

( homiciil
(Dnk'of iv^iiliilioni
CJ
'	
/. —
o
ed
- ^
-n-.
= _
CJ 2
'3 r. o
^ <- •¦=
_ — - 12
^ = w
5 a o ^
=o i -a y.
S. "S3 tz
y uj
— '— S.
G ° ^
2 £ ^ = 3
'2 ~ ~ = -r
^|if|2
" *3 -5" 5 w 1
M ^ 7 '3
r: ^ = o J
— ^
£
CJ
¦/".
UJ
>
s
lis i!
-1. = ^ w
—	2 - c -
—		 —	^ _
^ c5 a. jj uj
<¦* 'j — _
Q c/i
0£ ^ U.
_
.2 o ¦-> = 2
•= ^ a. -a
^ ^
— = ^ * o
:j - - o - =
o — -a £ ^
^ O 'J <¦ °
w - £ c_-
~5c .= 75 > CJ
p 8 §"J§
_
3 o o '± 2
7J lit.!
on 5j) ^ 2 .2
tJ '3 1 I I
u i: -o ; a.
^ o 'J <¦ ~
-	. / S —
-	x- = o 7
-	" £
Lindane mamma-
o ooo:
				
D.DDD" D.V,
( . I'ussihle hiinian
DDI
D DDI) i
—
0.004"7
Simuesih e
1 Icviclikii'ncsckihcviiic)


(\o\i:i.i
caicinnucii (1 *JS(n

( l'JS(.h) D V,

(2002m5"/ 0.4"7
c\ idence ol'
(IWI.U)


looo (loll.
Ill V IDS)
uiiidelines)
l\ilcnc> 1 ' per

(\o\i:i.i
iDDDllDll.

iNOAI'.l.)/ 100
(1011. I0A)/
cai'ciiKiueiiicil>.
hm urn snfliciciii in



I .in CI' and
nm ku das.
:d"„
ID \. IDS)

l-'QPA: 3
assess human



kid lies
Driiikiiiu ualcr

l.i\ei and

llopiiloolc
carciiinucinc



lii\icil\ k('( .
cniicciiiialinii al Id

kidnes

Inpcrlropln.
pnlenlial (



I'lSl
risklc\cl ' Id
iiiu 1. (ISWi: ^
l.iiicaii/cd
ninliisiaue model
\lsn
I'aclni'
111" |D
lur
class
(
ln\icil>
/.nccon (nip.
IWl

inciviisod li\or
nciglil.
inciviisod
pl;ilck-ls/ Aimcs
l9S«)si.h. I9«)j
mi idol i lies. 2dd2I'i
59 Using the RfD of 0.0047 mg/kg/day and assuming 70 kg body weight, 2 L/day water consumption, and a 20% RSC, a potential new MCLG derived from this
value is 0.033 mg/L (rounded to 0.03 mg/L).
107
-------
Six-Year Review 3	SUMMARY HEALTH EFFECTS ASSESSMENT REPORT	December 2016
Table 28b. Summary of Assessments by Other Organizations: Lindane (gamma-Hexachlorocyclohexane) CASRN 58-89-9
( homiciil
ATSDR
("si ii-: pa
WHO
Includes .ll ( I-A.
.IMPK.CICAI). I.IK
Health
Canada
\AS
Ijc.ir)
IAKC
(j o;i r)
Ml. IIS
(\e;ir)
•*».
OJj _
^ s
2P o
— **.
—
5
CD
/ 	
¦_
CJj
S <•>
**.
= ~
*— ~
'J T. ¦_
-> '¦> 71
5 S °
•" y. ^ •
w C/5
~.
n 5
E- ^ ~
ii W =0
¦s .2 ^ 2.
g 2 =P w
"5 — -
H
2
Mi
= i— o
'  •
O c/)
W
— 'J z, —
EE „o —
•E a. s ^ o
~ > O w
?
w -
o
o r:
— •	
•" /*.
W /.
1.Midline mamma-
11 c\ac 11 In i'i v> c In 1 ic.\a i ic)









kcasniiahK
aiiliapalcd In he a
human caraimucii
(:o|4)
108
-------
Six-Year Review 3
SUMMARY HEALTH EFFECTS ASSESSMENT REPORT
Table 29a. Summary of EPA Assessments: Methoxychlor CASRN 72-43-5
December 2016
( hemiciil
(l)iilo of
ivuuliilioii)
I .S. I.PA/OW National Prim an Drinking \\ siicr
Rctiiilalion (\PI)\\ K)
I .S. I-'. PA IRIS
I .S. IP A OPP
U
CJ
'	
/. —
7 w
Id
=P -n-.
= _
w /-
- £
flic
t°ls
= u
G •= D_
o£ <£ 3 jx
S y '-> o
Sli 5 y 2. V,
c/} — ^ s ^ o
C/5 Zr, ~ — — C —
7" <— pL " - 7. o
J - r * 3 - =
o b ^ •£. ^ ^
y o o " ±
- > - J
w - -
l)\\ 1 !l. mm I. > tV;
kSC
llsil
dj • — ^ O
s d -z _
=0^- Sb [j
— — •— s ¦ J
c s a p u
o j - _
'— — n;
_
2 y ¦-> o
£2= 5 y EL •a
y. — — — — —
C/5 — — — S2 —
-H — i- ~
¦t - /J3- =
o b S ^
y j j 'j " ^
= > - j
w - -
|| fefl
CJ) .= >5 > ^
z* d -z
«^ = -§ O
C3 Q. p hj
/-V O O - —
Cr —
c£ u.
—
2 o o s
S ^ 5 y £L •a
c/) — — S2 —
-K — =. £ - ~ o
J - r ^ 3 - =
o b 9" £ ^ ^
y o o " ^
= > - j
0 ^ " <2
Mclhuwdilur
(iwim
0 04
oo4
0	005 5.o|
(\<)\i:i.)
1	000 ( loll.
10 V lo|)i
1 Ai_Vssl\ e
kiss nl' lllkl's.
decreased
hnd\ uemhl
1 I'llllcr. l'JX
(1 'JS(n uuidcliliesi
o I "5
:o"„
0	oo5
(iwohi 5 01
<\o\i:i.i
	1		loll.
lo \. lol))
1 ACCsslN c kiss
ill' llllei's
kmcaid
1 illk'ipi'lses.
I'JS(.
1). \m classi liable
as in hiiiiiaii
carciiinueiiicilv
( I'JXih mndcliiics.
IWIn


109
-------
Six-Year Review 3	SUMMARY HEALTH EFFECTS ASSESSMENT REPORT	December 2016
Table 29b. Summary of Assessments by Other Organizations: Methoxychlor CASRN 72-43-5
( homiciil
ATSDR
( iill l'A
who
Includes .ll ( I-A.
.IMPU. ('I('AI). I.IK
lloiillh ( iiiiiidii
NAS
(joiiri
IAUC
(jciiri
y: —
= =
^ C
/ -
$P o
2 ^
50^^
« = ^ H -
f>£ | J m 1
1 t l|IS
— — -5 ~~
( aiicer
cla^Mficalii'ii
(> can
E— 5 ^
^ ~
g 5 2P w
~z, — ~
H
.0
5 0 i
S J— O
. • - y. «" ¦
O C/5 s—^
~
— 'J z. —
EE ~
.= H. s r 3
~ V O w
.5 d a " -
^ ^
S
— .
O - ¦_
r:
s s 0
¦" s. C,'
~
Mcllkiwdllni'

0.00002
(201 Oil
/0.02
(IO\ll)/l	
(III.\.Hill.
lOl.i/inciViiscd
proslnilo iind
somiiiiil \esicle
weights in
mico/.lii(l> el
ill. !«)«)•)
( iircino^onicil>
si 11 dies iiiv
in;i(k'(|u;i(o In
prcscnl
sliindiinls
(201 Oil)







60	The public health goal derived by CalEPA is based on noncancer effects. The RfD-equivalent shown was calculated based on the LOAEL and UF provided by
CalEPA for noncancer effects.
61	Using the RfD of 0.00002 mg/kg/day and assuming 70 kg body weight, 2 L/day water consumption, and a 20% RSC, a potential new MCLG derived from this
value is 0.00014 mg/L (rounded to 0.0001 mg/L).
110
-------
Six-Year Review 3
SUMMARY HEALTH EFFECTS ASSESSMENT REPORT
Table 30a. Summary of EPA Assessments: Oxamyl CASRN 23135-22-0
December 2016
( homiciil
(l);ili- of
rciiiihilioni
I .S. IM'A/OW \;i(ion;il Priniiin Drinking \\ ;i(cr
Rciiiiliilinn (NPDW R)
l .S. I-'. PA IRIS
I .S. IP A OPP
CJ
•	
/. —
7 C
Id
_ ^
= _
CJ 2
>1 o|
1	S J
n. o ^
>;
^ ^ £ UJ
2	Lu ^
& £ => ^
2 y
S ."S •§ 5 y Q. •a
(/) — 2 Z ^ — O
c/) JZ
¦7; t— H. " - "
J - r y 3 - =
O = -3 ± z ¦-
j -j ~
= > - j
w - -
>cj
_ -
UJ
>
=
i'5 2 § y
5-o o
— _ •_ ~ ¦j
0 c3 S. p uj
^ ¦> =¦ _
'— — n; J
Qi. U.
i 0 s
S ."2 -i 5 y O. •a
— — — —
c/j — S2 —
-H •— =. £ - ~ 0
,J - ; y 5- =
0 b ^ ^ ^
j -j " —
= > - j
O — S
llSfl
CD > O
Z, d Z
= ¦§ y
r: Q. p m
~ 0 0 - —
— -r j
2 0 ¦-> s
5 y §.¦§
4 y. 5 7 7 = 7
1	c f V 3 - =
2	5 <3 — 2
= > - j
0 w " <2
(Kaiml <\ ulalei
(l'w:h)
o:
u.:
DO25 : 5
(\<>\i:i.)
luo (loll.
I()\)
decreased
hnd\ uemhl
uain
keinieds.
I'«(.
1!. 1 idence nl'
iK)iicaiviiK)ueiiicil>
(1 *JS(n mi idol i lies)
0
:u"„
0.0:5
i I'jsi.mi : 5
i\oi:i.i 100
1 loll. |0 \|
decreased
hnd\ wemlil
nam and lood
coiisiinipiioii
1! 1 du l\mi de
\eiiK)iiis and
( umpaiis.
IT2

<20l0e)/lU»(.y
(ISM 1)1.1..)/ 10
(lOlh/AccM
ch(iliiK'sk'i;iso
inhibition in
hiiniiin rod
hl(Mi(l cells
1!. 1 idence nl'
iKiiicaiviiKiueiiicil>
( I'^Si.i miidelmes.
:o|oei
62 The RfD for oxamyl is an acute RfD of 0.0069 mg/kg/day based on acetylcholinesterase (AChE) inhibition in human red blood cells. A chronic RfD was not
derived because of the rapid recovery of AChE activity and an acute exposure based RfD that is considered protective for chronic exposure. The potential new
MCLG of 0.1 mg/L is derived based on a 10 kg body weight and 1.0 L drinking water consumption and an RSC of 20% as follows: 0.0069 mg/kg/day x 0.2 x
lOkg/lL = 0.0138 mg/L. An alternate potential new MCLG of 0.009 mg/L can be derived for children from birth to less than 12 months at the 90th percentile of
0.15 L/kg (U.S. EPA, 201 la Exposure Factor Handbook, based on Table 3-19) as follows: 0.0069 mg/kg/day x 0.2 x 10kg/1.5L = 0.009 mg/L.
Ill
-------
Six-Year Review 3
SUMMARY HEALTH EFFECTS ASSESSMENT REPORT
Table 30b. Summary of Assessments by Other Organizations: Oxamyl CASRN 23135-22-0
December 2016
( homiciil
ATSDK
( ;ih:p \
who
Includes JIX I-A.
JMPK.CICAI). I.IK
lloiillh ( iiiiiidii
\AS
(\c;ir)
IAUC
C \ Oil 1")
y, —
= =
^ £
/ -
~ -i.
^ op ^
CJj
s —
CJj C3
£ o
= ~
S
~
o r: ¦_
¦> '¦> 71
SCO
' w
W C/5
£5 s-
H 5 ^
M ~ ~
^ -£. **•
H 3 ~
~z, — ~
H
5 ^ =
S °
'(/I
O C/5 S—^
G
~ o 5
™ ^
•E a. s o
x p o O >.
U ^
•_ 3
o r: ¦_
-> r:
5 S °
•" y. ^ •
w C/5
()\am> 1 (\ ulalci

().()()(,
(2oo%)
63
( lassi licalinn urn
sialal. hui indicates
n\am\ 1 is mil a
miiiaucii or
caiciimucii <2
-------
Six-Year Review 3
SUMMARY HEALTH EFFECTS ASSESSMENT REPORT
December 2016
Table 31a. Summary of EPA Assessments: Pentachlorophenol CASRN 87-86-5


I .S. I-'.PA/OW \;ilion;il Prim;ir\ Drinking

I .S. I-'. PA IRIS
I .S. IP A OPP


Wilier Ketiiihilion (NPDWK)

( hcmk'iil
(Diilo of
ivuuliilion i
CJj
/. —•
c. ^
— '
— 7
CJj •%.
i
CJ 2
s*
EL Ji ^
|ejl
— — ~
~ f —
o o ¦> o
7 E 5 - — "o
•r: H. $ — ^ o
o o cr o rT1 s
W 	
CJj r ,
3 S
I3! y § §
P " ° _Q ^
"""'
1 £ o 5
*7* d. H. ^ — * o
o ^ . UJ ^
= 5 1"" 1
•w' "™" 	
I3-! y §5
ill
G " Q £ ^
— S. —
± 'J. J s
^ o § EL "q
*7* H. ^ — * o
¦> - ~ 'J — • • —
m"Y
•w' 	
IViiladiloropheiiol
0
0 (K)|
nil! !
13:. I'rohahle
1 1
0 005(:o|od)
l.ikels Id he
o oo5 (:o()Shi
IS:. I'rohahle hiiniaii
( I'Wlei

(POL.
(\o\i:i.i
hiiniaii caivmoueii

15(i.o\i:i.)
caiviiiouenic lo
i 5(i.o\i:i.i
carciiioueii < 1 'Mm


;in;il\lic;il
loo ( loll.
111>S(h uuideliiieM

!()() (loll. IDA.
hiiniaiis i:oo5a
"!00 ( |0| |. |0 \.
uuideliiies; :ooShi


lc;isihiln\»
1 () \i
I'oleiics (i i: per

M.i
uuideliiies. :o|od)
M.)
l\)leiics o o" per



pmmeiilalioii
iiiu ku das.

1 lepau>u>\icil>
l\>leiic> ' o 4 per
1 lepaloloNicils
nm ku das. 1 )rnikiim



dI" kid ne\ s
Driiikinu ualer

\1eder. 1 wi>
iiiu ku das.
\1ecler. 1 l>lH,
waler coiiceiiiralioii



Sdiuel/ el
coiiceiiiralioii al In


Driiiknm ualer

al lo risk le\el



al. ITS
risklesel ' I"
mu 1. (IJWi: !
I.iiieai'i/.ed
muliisiaue model


coiiceiilialion al lo
risklesel l> lo
mu 1. 115\\ )! 4
Mullisiaue model
wnh linear
eMrapolalion I'rom
die I'OI) il.i:i)|oi

5 lo iiiu 1.
(li\\ )" 4 l.ineari/ed
miillisiaue model
58 An IRIS assessment (U.S. EPA, 2010d) for pentachlorophenol states that under the 2005a Guidelines PCP is "likely to be carcinogenic to humans." A
multistage model using linear extrapolation from the point of departure (based on increased incidence of hepatocellular and adrenal gland tumors in male mice)
was performed to derive an oral slope factor of 4 x 101 (mg/kg-day)"1 for PCP. The recommended slope factor should not be used with exposures greater than
0.25 mg/kg-day (the point of departure for the site with the greatest response for tPCP-exposed male mice), because above this point the slope factor may not
approximate the observed dose-response relationship adequately.
113
-------
Six-Year Review 3	SUMMARY HEALTH EFFECTS ASSESSMENT REPORT	December 2016
Table 31b. Summary of Assessments by Other Organizations: Pentachlorophenol CASRN 87-86-5
( homiciil
ATSDK
(iiir.PA
WHO
Includes J IK T'A.
.IMPR.CICAI). I.IK
1 k;il111 ( iiiiiidii
N AS
(jc;ir)
1 ARC
(\e;ir)
y: —
= =
/ -
-¦».
OJj
o
— **.
_
5
CJj
s —
CJj C3
= ~
•— ~
' J - ¦_
-> '¦> 71
5 S °
•" y. C.'
W /
B. ^ £'
H ^ ~
.2 ~ =o r,
¦2 J2 2.
g 2 2Pw
"E — ~
E—
o
Mi
s <— O
. • - s. «" ¦
O C/5 s—'
~
— -j z, —
^ O
• E O. = - 3
x p o O >.
^ d a - -
¦" " ?
o ^
~
o r: ¦_
-> r:
jC 9
•" y. C.'
w C/5
IVnliidiloi'ophenol
~
(tool
h'o\ en carciiinucii
-
~
~
"
~
~
kcasoiiahk



mi rude in Mi id ics






aniicipalcd lo



u uli some






lv a hiiniaii



epidemiological






caiviiioucii



c\ idcucc (Juu'Vi






<:ul4i
59 The public health goal derived by CalEPA is based on carcinogenic effects. The RfD-equivalent shown was calculated based on the NOAEL and UF provided
by CalEPA for noncancer effects.
114
-------
Six-Year Review 3
SUMMARY HEALTH EFFECTS ASSESSMENT REPORT
Table 32a. Summary of EPA Assessments: Picloram CASRN 1918-02-1
December 2016
( hemiciil
(l)iilo of
ivuuliilioii)
I .S. I.PA/OW Niiiioiiiil Priniiin Drinking \\ ;ilcr
Rciiuliilion (\PI)\\ K)
I .S. I-'. PA IRIS
I .S. IP A OPP
U
CJ
'	
/. —
7 w
Id
=P -n-.
= _
w /-
- £
flic
t°lg
G •= u_
C£ £ 3 ^
2 o s
y. — — — — —
C/5 ~
7" <— ^ T? o
J - r i =¦ - =
o b 9" £ ^ ^
J. -j 'j " ±
- > - "J
w - -
l)\\ l!l. mm 1.) A:
kS(
cX) • — ^ O
=o E -o o
ci a. 8 uj
<¦* -j o - _
'— — "ZT '
_
2 o ¦-> o
S2'i 5 y Q. •a
y. — — — — —
C/5 — — — S2 —
-H — i- ~
¦t - /J3- =
o b S ^
y o o "
= > - J
w ~ -
11 = 11
CJ) .= >5 > ^
z* d -z
«^ = -§ O
c: O. p m
o o -
— — y.
Qi U_
_
-j o
S ^ 5 y EL ^
y. — — — — —
 - J
0 w " <2
hclnrani (l'W2h)
(i 5
(1 5
no- "
<\o\i:i.i
I<>() ( |()| |.
Ill \)
Increased
rclali\c and
ahsnluic 1 in cr
wciuhls l)n\\
( hcmical
(umpam.
I'JX:
1). \m classifiable
as in human
cai"ciiKiucuicil>
11 'Win uuidcliucs)
: 45
:o"„
0	u" ( I'lS'ci
"(\oi:i.i loo
1	loll. |0 \)
Increased
i'clali\c and
ahsnlulc 1 in cr
wcmhls l)n\\
( hcmical
( umpam.
I'JS:

0.2
(NOi:i i/ ioo
(ION. I0A)/
Ch.ingi's in
ccnlrilohiiliir
lu'|);Uoo (os/
l.iindn ol
ill., im
ii :\ idcucc i>r
IKHICai'CIIKiUCIIICIl>
( I'JXih uuidclilies.
|w5hi
60 Using the RfD of 0.2 mg/kg/day and assuming 70 kg body weight, 2 L/day water consumption, and a 20% RSC, a potential new MCLG derived from this
value is 1.4 mg/L (rounded to 1 mg/L).
115
-------
Six-Year Review 3
SUMMARY HEALTH EFFECTS ASSESSMENT REPORT
Table 33a. Summary of EPA Assessments: Selenium CASRN 7782-49-2
December 2016
( homiciil
(of
rotiulalioni
I .S. I.PA/OW National Priman Drinking \\ ;ilcr
Rctiulalion (\PI)\\ K)
1 .S. I-'.PA IRIS
I .S. IP A OPP
CJ
'	
/. —
7 C
Id
- ^
=P -n-.
= _
CJ 2
/
'o ,T o
a-!iu-=
_ — - 12
5 5 o ^
m i: -o "
¦=£ s. tz
G ° ^
2 o o '± z
'1 ~ ~ = -if
||
" *3 -5" 5 uj i
= . j. s- ~
7Z ^ = 'J —
— '¦ ¦—
w — —
CJ
¦/".
UJ
>
s.
= —
o — c
r r= 2 1
£ 1 £ 5
5 a. o o
|?n s=
ZD <— p UJ
a -
e "i S
- -
2 o o 5 T
.'1 ~ ~ = -r
^l|lf |2
" *3 -5" 5 uj i
M ^ f '3
= . y. J-.
— = 'J —
— ^
W / 	
= —
O — -
= = 2 =
£• c > U
^ EL S —
tnll
y Uj
G 3 ^
~ -
2 £ o '± l
l||f |2
" *3 -5" 5 uj 5
= . ~ ' TT
r: ~- = o ^
— ^ —
w / —
Selenium (I'wlln
0(15
0(i5
Nunc ' : 15(11.
1.. accnuiiliim fur
special Mains as
essenlial elemeiili
\1 miiiiiini dielarv
inlake nf selenium
mi area u illi
clirniiic selennsis
nf iiiu da>. fur
a "ii ku adnll "S'anii
el al . I')S1

50".,
0.005 (1 wlln
o 0 15
(\()\i:i.i ^
('III Cluneal
seleimsis
Yaim el al .
I'WJ
1). \m classi liable
( I'JXih uiiidelilies.
IWOd)


116
-------
Six-Year Review 3	SUMMARY HEALTH EFFECTS ASSESSMENT REPORT	December 2016
Table 33b. Summary of Assessments by Other Organizations: Selenium CASRN 7782-49-2
( Ik-iii ic;il
ATSDR
( iill l'A
WHO
Incliuk-s JI.CIA.
JMPU. CICAI). i:il(
1 k;il111 ( iiiiiidii
N AS
(\c;ir)
IAKC
(\c;ir)
/. —
= =
^ C
y -
-¦».
CJj
•-
£P o
~ .
—I w
J
"3
op
e
Caiieer
elasMliealiiiii (\ ear)
a 5
ii w =0
¦S £ ^ "
~z, — ~
H
2
Hi
S °
. • - s. ¦
O C/5 s"-'
~
— _j o ^ o
- o s ~ ^
EE x> "p o £2 c2
—
**.
S-r
o 2
a |
/.
j.
~
Selenium
~
(1.1)1)5
\nl assneialed
0 4 iiiu d
Does urn appear
0.05 (2014;i0.4 m»/clsij
-
~
~
-


(2<) |oh)
wuh increases m
upper
In he
(I pper1 .imil):0.2 ((k-liiull







liumaii eaueer
Inlerahle
carciunueuic
;illoc;ilion lor drinking







niles Mas lm\e
iniake
(2o| le. WHO)
\\;i(en:l.5 l./d;i\/ Chronic







eaueer prniecli\ e
(201 le.

sclcnosis/







properties
wmo)

IOM 2	







(:o|()h)







61 Utilizing the IOM (2000) Tolerable Upper Intake Level (UL) of 0.4 mg/day for adults with critical effect of clinical selenosis the MCLG could decrease. The
potential new MCLG would be 0.04 mg/L using 0.4 mg/day or 0.2 mg/L assuming 2L daily water consumption and a 20% RSC.
117
-------
Six-Year Review 3
SUMMARY HEALTH EFFECTS ASSESSMENT REPORT
Table 34a. Summary of EPA Assessments: Styrene CASRN 100-42-5
December 2016
( hemiciil
(l)iilo of
ivuuliilioii)
I .S. I.PA/OW National Prim an Drinkinii \\ akr
Rctiiilalion (\PI)\\ K)
I .S. I-'. PA IRIS
I .S. IP A OPP
U
CJ
'	
/. —
7 w
Id
=P -n-.
= _
w /-
- £
flic
t°lg
G •= u_
C£ £ 3 ^
2 o s
y. — — — — —
C/5 Zr, ~ — — C —
7" <— = $ - 7. o
J - r ^ 3 - =
o b ^ ^ ^
J -j 'j " ^
= > - J
w - -
l)\\ l!l. mm 1. i tV;
use
11 = ll
cX) • — ^ O
M0- 5 T3 o
c5 n. p dj
<¦* -j -> - _
'— — n;
0£ U.
_
2 o 'j s
S :s •= 5 5 g. -a
;/> — s z ^ — o
C/5 — — — S2 —
-K ~ Ti
J - r ^ = - =
¦j - — i- ~
'J. -j 'j " .2
= > - J
0 ~ " <2
|| fefl
CJ) .= >5 > ^
z* d -z
— —
c: O. p m
o -> —
— — y.
Qi U.
_
S o 'J o
S :§ •= 5 y S. "S
y. — — — — —
 ^ ~ s — iX
^ ^ (/) f/}
:j f" v 3 - =
2 ^ — 2
= > - J
0 ~ " <2
Sivreiie (I'^lm
0 1
U I
0	: 200
(\o\i:i.i
	1	loll.
10 \. |()S)
Reduced red
hku»d cells.
mum deposiis
mi li\crOuasi
el al . I1)-1)
( . possible liiimaii
carcuinueii (I'JXiii
uiiideliiiesi
l\>leiic>. ' Id per
nm kii da>.
Driiikinu waler
cuiiceiiiralimi al Id
risk lc\el 1 Id
in- 1. < I5\V)2 ^
l.nieari/ed
niiiliisiaue mudcl
7
2o"„
0.2 (I'JXxl)
2do(\o\i:i.)
IDOOIIOII.
lo \. I OS i
Reduced
heiiK
-------
Six-Year Review 3
SUMMARY HEALTH EFFECTS ASSESSMENT REPORT
Table 34b. Summary of Assessments by Other Organizations: Styrene CASRN 100-42-5
December 2016
( homiciil
ATSDK
( iill l'A
WHO
Includes .MKT"A.
JMPK. ('I('AI). i:ik
llciillh ( iiiiiidii
N AS
l\c;ir)
IAUC
l\c;ir)
MI.IIS
l\c;ir)
o£ =0 yi
sp ^
33
¦=£ "D
CD
— 'J
**.
= -
z.
'J - z.
-> r:
5 G o
¦" s.
.
I-5C
.2 w =o ?=
x> 4 PS °
— ~
E—
.o
5 ^ i
s <— O
7 «"¦
w / "
~
- -J z. —
B ^ ~ ^
= 5. = .- 5
^ > -j w
.5 . a - -
¦" " ?
s
o - ¦_
-> r:
S C o
¦" s.
•w /
Si\ ivno
\n
IUMP
Sufficient c\ idcncc
—
~
—
—
kcasonahk
--
keasonahK

iiilcmicdialc
mii/k*i/cl
lliiil s(\ivnc c;iiincn




aiilicipaled

aiilicipaled

ni" chronic
(2010c)"-
Ciincor in iininiiils




In he a

Id he a

oral \1kl.

iind limited




liiiniaii

human

C()|();||

o\ idcncc in




eaiviiioueii

eaiviiioueii



linniiins (211111c)''1




i:u|4i

i:ol4i
62	The public health goal derived by CalEPA is based on cancer potency. The RfD-equivalent shown was calculated based on the NOAEL and UF provided by
CalEPA for noncancer effects.
63	The potential new MCLG could be 0 mg/L based on a possible human carcinogen.
119
-------
Six-Year Review 3
SUMMARY HEALTH EFFECTS ASSESSMENT REPORT
Table 35a. Summary of EPA Assessments: Thallium CASRN 7440-28-0
December 2016
( homiciil
(l)iilo of
rciiulalion)
I .S. I'.PA/OW National Prima r\ Drinking Wali'i1
Rciiiilalion (\PI)\\ K)
l .S. I.PA IRIS
I .S. IP A OPP
1
O
CJ
•—
/ —
7 C
Id
=P -n-.
= —
w --
- o £
1' 1 M
~£b a. o ^
s <3 *=
^ ~ x> uj
Q u_
2 o s
y. — — — — —
(/}
-H — =. ~ o
.J - r ^ 3 - =
O = -3 ^ ^ r
^ O *J " ^
= > - J
0 ~ " <2
3 V
_ -
UJ
>
c.
ti^f
cd • — ^ O
S -J ? _
S-o o
— — •— s ¦ J
^ C3 S. p UJ
o o - _
'— — n;
q£ U.
_
2 o ¦-> s
S ^ -S 5 y EL ^
C/5 — — S2 —
7* <— H. « - T< o
J - r ~ 3 - =
O = -3 ^ ^ -
y o o "
= > - J
0 — " <5
|| fefl
cX)> O
Z, d Z
= -§ O
C3 Q. p rn
/-V O O -
'— Cr — ~
C£ U-
—
2 o o s
S ."S •= 5 y E. •a
(/) — s ^ — O
(/} — — S2 —
-H — =. '¦ - ~ o
J - r ^ 3 - =
o b ^ ^ ^
y o ^
= > - j
0 — " <5
Thallium
(|w:h)
00005
odd:
(I'HI.)
ooooo- o :5
(\o\i:i.)
'1100 ( loll.
10 \. |0S. '1)1
\n licaliiieiil
rclaled elTecls
Sinl/ el al.
I'M.
1). \m classifiable
as ik Iiiimaii
caiviiinuenii.il>
( I'JXm miidelnies)
o oo:
:o"„
\l) kl'l)
dcri\ cd due in
piun qiialil> of
dala (2oo<);i)
Inadeqiiale
iiifniiiialkiii in
assess cai'ciiinucinc
pnlenlial <2oo5a
uuidelilies. 2ooiJ;n


120
-------
Six-Year Review 3
SUMMARY HEALTH EFFECTS ASSESSMENT REPORT
Table 36a. Summary of EPA Assessments: Toluene CASRN 108-88-3
December 2016
( homiciil
(l);Ko of
ivuiiliilioni
I .S. I.PA/OW Niiiioiiiil Priniiin Drinking \\;iii*r
Ki'Uiiliilion (\PI)\\ K)
I .S. I.PA IRIS
I .S. IP A OPP
U
'	
/. —
7 C
Id
_ ^
=p -n-.
= _
>| o 1
| S J ~
co n. o O
'¦> -i —
S <3 & *=
w Z. uj
G •= u_
Qi (£ 3 ^
2 o '-> z.
52 = 5 y EL'g
y. — — — — —
C/) — — C —
-H — E. ~ o
J - r ^ 3 - =
o b £ a -g
J -j 'j " ±
- > - J
w - -
3
_ -
UJ
>
fl fell
cX) • — ^ O
=0 5 T3 y
^ ^ ^ cz
0 S S. 8 uj
<¦* o o - _
'— — n; J
~
_
2 o
y. — — — — —
IS) — — — 12 —
-H ¦— ' ~ o
J - r ^ 3 - =
o b £ 2 -g
J -j 'J " —
= > - J
J - -
|| fefl
CJj > O
S d -Z
= ¦§ O
— _ •_ S.J
~ r-. — :j ~
-• -J -> —
e£ u_
_
s O ¦¦> o
!=!•= 5 y E. ^
y. — — — — — —
— T — — —
7"3 IT / / —» —
.'J ^ jys- =
2 ^ — 2
= > - J
0 ^ <2
Toluene (I'^lm
1
1
().:
(\o\i:i.i louu
(loll, lu.v
|uS) Increased
kiduev uciulil
\'IP. Vwii
1). \oi classifiable
as i« human
cai'ciiKiucuicil>
( I'JXih uuidelines)
"
0.0X (2005c)'-4/
23X (15 M1) 1.)/
		(Kill. 1 OA.
I0S.3I))/
liicic'iisod ki(lnc\
n eights/ N I P.
I9«)0
Dala arc iiiadcqualc
In assess
carciiKiuciiic
poicuiial i2o()5;i
uiiidclincs. 2oii5ci


64 Using the RfD of 0.08 mg/kg/day and assuming 70 kg body weight, 2 L/day water consumption, and a 20% RSC, a potential new MCLG derived from this
value is 0.56 mg/L (rounded to 0.6 mg/L).
121
-------
Six-Year Review 3	SUMMARY HEALTH EFFECTS ASSESSMENT REPORT	December 2016
Table 36b. Summary of Assessments by Other Organizations: Toluene CASRN 108-88-3
( lu'iniciil
ATSDR
( ;ili:p \
WHO
Includes JIXTA.
JMPU. ('I('AI). I.IK
Health Canada
N AS
(jc;ir)
IARC
(jciir)
/. —
= =
-J C
/" -
.
OJj _
2P o
— **.
—
5
CJj
/¦ .	
¦_
CD C3
~.
= ~
o
*— ~
'j - ¦_
-> r:
= o
•" ~
•W /,
B. ^
.2 w so «
¦e 2 ^
"5 — ~
E—
2
5 5 =
E
w
~
— o t) —
E X) —
•E asp §
~ y 'j w
^ d a "
2 r:
E ¦-=
•" y. ^ •
•W /
Toluene
--
--
--
-
-
0i)(1(:()l4h)
\nl classifiable due In
-
-
-







iiisul'liciciil animal and hiiniaii










caiviiinueiiii.il> dala <2<)l4bi



122
-------
Six-Year Review 3
SUMMARY HEALTH EFFECTS ASSESSMENT REPORT
Table 37a. Summary of EPA Assessments: Toxaphene CASRN 8001-35-2
December 2016
( homiciil
(l);Ko of
rciiiilalioni
I .S. I.PA/OW National Primar\ Drinking Walor
Rciiiilalion (\PI)\\ R)
I .S. I-'.PA IRIS
I .S. IP A OPP
CJ
'	
~ —
7 w
Id
- ^
-n-.
= _
w ^
- -d '-= £
1	H J
n. o ^
U ^3 ^
2	<3 & 8=
w Z. •£> uj
G u.
<*¦ c£ ^ ^
.2 o ¦->
S 1 •= 5 y n.
y. — — — — —
c/j JZ
¦f; t— H. " — 7.
¦t r ^ 3 - =
o b ^ •£. ^ ^
J. O 'J " ^
= > - J
0 ^ " <2
_ -
UJ
>
11 = Is
cd • -- ^ O
S -J ? _
=0 5 T3 y
— _ —
° C3 S. p UJ
^ o o - _
'— — n; J
cC U.
_
2 o o o
ill 5 y g. -a
;/> — s z ^ o
W —
¦f; t— H. " — o
J - r ^ 3- =
o h ^ ^ ^
J. -j 'J " ±
- > - J
0 w " <2
||S°|
OX) ^
=¦§ o
c: a. p m
^ -J -J - —
— -r v.
Qi U.
3
S i ° ^
'¦= "2 = 5 5 S."3
y. — — — — —
^ ^r, — S — S2
" LI /. / — «
.'J ^ r is- =
2 ^ — 2
= > - J
0 — " <5
Tuvipheiie < I'^lm
0
		
(KM.)
oi)i)()4 o.^i.
(\o\i:i.i loo
(loll. |o \. 10
\1l ' I'm'
iieurndeN elup
menial and
ininiMiK
1 1 per mu ku da>.
Drmkiim ualer
cuiiceiiiralinn al lo
risk le\el ' \ lo
in-1. (iswi: ^
l.iiiean/ed ninliisiaue
model


152. Pmhahle liiiiiian
eaiviiKiuen (I'JXc.i
mi idol IIICV. I'Wk)


123
-------
Six-Year Review 3	SUMMARY HEALTH EFFECTS ASSESSMENT REPORT	December 2016
Table 37b. Summary of Assessments by Other Organizations: Toxaphene CASRN 8001-35-2
( homiciil
ATSDR
( iill l'A
who
Includes .ll ( I-A.
.IMPU. ('I('AI). I.IK
1 k;il111 Canada
NAS
(\e;ir)
IARC
(\c;ir)
/. —
= =
^ c
/ -
Ss
= i-
CC
V1
CD
£ o
= ~
S
'J ~ ¦_
-> '¦> 71
= O
•" I
•w /,
f 2
E— 5 ~
M ~ ~
x> ° ^
i- C3 Cp
"s — ~
E—
2
M =
E °
O C/5 N—''
~
— O C. —
E 3 " ^
•E a. s r o
~ V w
^ d a - -
^ ^
w -
~
o r: ¦_
-> r:
=
•" y. ^
' /
1 nvipliciic
		
~
~
-
--
~
~
~
~
keasniiahK

inlennedmle








aiiliapaled M he a

(:o|oh)








human caivninucii










<:<>I4)
124
-------
Six-Year Review 3	SUMMARY HEALTH EFFECTS ASSESSMENT REPORT	December 2016
Table 38a. Summary of EPA Assessments: 2,4,5-Trichlorophenoxypropionic Acid (2,4,5-TP; Silvex) CASRN 93-72-1
( hemiciil
(l)iilo of
ivuuliilioii)
I .S. HP.VOW National Prim an Drinking
Wilier Rouiihilion (\PI)W K)
I .S. I-'.PA IRIS
I .S. I-'.PA OPP
U
CJ
'	
/ —
/ w
iz
- /
2P -n-.
= _
CJ 2
- -± o £
ills
tsis
s <— p £
G •= u.
2 u '-> s
7 "i s 5 5 §L ~=
: 7 j = f
— =. ~. — /
J - r * 3 - =
O = -3 £ ^ -
'j. -j 'j " ~
- > - j
J - -
>cj
3 '/¦
-j *
UJ
>
S.
ll = 13
cX) •— ^ O
5" e -a y
° S a. p uJ
o j - _
'— — n;
0£ U.
_
2 o ¦-> o
S :S % 5 y E. •a
y. — — — — —
in —
-H — =. '¦ - ~ o
J ' r y 3 - =
o b 9" •£. ^ ^
'A m'j 'J " -i
- > - "J
w - -
|| fefl
CD.= ^
Z, d C
«^ = -§ O
—	— ¦ J
—	x ™
r: — *j ¦ ¦
/-v O 'J — —
c — ~.
c£ u.
—
2 o o o
7 "i = 5 i i-l
^ ^5 7 9 H "=
— =L ~. - ~
.J - r i 3 - =
O = -3 i. * ¦-
j. -j 'j " ~
- > - j
w - -
2.4.5-1 P (SiKcn.
2.4.5-
Tridikii\>pliciHi\\
pmpioiiic \cidi
(IWIU)
0 05
0 05
0	oos o "5
<\o\i:i.i loo
(loll. IDA)
1	iNnpailkilnu-
ical chaimcs in
llic li\ or
MiiMisom. llK><>
i). \m
classifiable as in
human
carciiinuciiicilv
i l'JS(ii uindcliiicsi
0 ^
2o"„
o oos (I'JSSci
0	"5 i N( ) \l :i .1
		mil. io.\)
1	lisinpallinlnmcal
clianucs mi llie
li\ci" Miillisnii.
llK><>. (iclniim
and l.clsn. I'J"S
1). \m dassi liable
( I'JXlH HI lllld II ICS.
IWai


125
-------
Six-Year Review 3	SUMMARY HEALTH EFFECTS ASSESSMENT REPORT	December 2016
Table 38b. Summary of Assessments by Other Organizations: 2,4,5-Trichlorophenoxypropionic Acid (2,4,5-TP; Silvex)
CASRN 93-72-1
( homiciil
ATSDR
< ;ih:p \
WHO
Includes JIX 1 A.
.IMPK. ('I('AI). I.IK
Ik-allli Canada
NAS
(jwiri
IARC
(\ car)
MI.IIS
(j win
_ ¦= C
ai. =o
2 ^
^ op ^
CJj C3
— 'J
-¦».
= -
'J rz H
J '¦> rz
E ^ £'
H 5 S
J2 ~ =o ~
x> 4 ^ °
~
"5 — ~
H
2
5 5 i
= o
7 ¦
O t/)
~
- o o
E x) - ^
•= a. = -r- 5
X- O O w
da " "
o ^
o
o r: C
-> r:
£ C o
¦" 7
•w /
:.4.5-'ri'(Sii\cv.
2.4.5-
1 ndiliwplieii-
n\\ pmpiDiiic
Acid)

(l.()()() 1
(2nl4i
Prini;inl\ iicuali\c
animal caraiinueinalv.
and mi\ed cpidcminlnus
iiisull'iaeiil hasis in
sei\e as basis I'm-1*11 (¦
(2014)







126
-------
Six-Year Review 3
SUMMARY HEALTH EFFECTS ASSESSMENT REPORT
Table 39a. Summary of EPA Assessments: 1,2,4-Trichlorobenzene CASRN 120-82-1
December 2016
( homiciil
(l);Ko of
ivuiiliilioni
I .S. I.IW/OW Niiiioiiiil Prim;ir\ Drinking
Wsilcr RciiuhKion (\PI)\\ K)
l .S. I.PA IRIS
I .S. IP A OPP
w
CJ
'	
/. —
7 C
Id
_ ?
=P -n-.
= _
w ^
/
-	o I
tip
s <— P ci
-	Z i w
G-Su.'S
S. ^ ^
S y o
Si! 5 y EL-a
y. — — — — —
(/} — — C —
-H ¦— E. ' - ~ o
J - r y 3 - =
o b 9" £ ^ ^
y o o " _i
- J- L -J
0 ^ <2
r S-
-J *
UJ
>
fl = 1s
cX) • — ^
z, d -z ^
= •§ y
^ ^ ^ c;
0 S S. 8 uj
<¦* o - _
Q t/i
c£ u.
_
2 y ¦->
sll 5 y EL •a
c/j — ^ ^ — o
(/) —
-H ¦— E. ' - ~ o
•J - r * 3 - =
O = -3 ^ ^ -
y ;j 'j " ^
= > - j
0 ~ " <2
Is fell
CX) > O
^ O B £ ---
= ¦§ o
—	— •— S.J
—	x "
r: — ¦ ¦
-j o -
c- — ~ '
_
± -J s
5s-= 5 y EL "2
;/> — s Z ^ o
^ ^r» -= 5? — ^ —
™ LI /. / —» «
i ^ =
^ in — 2
= > - j
0 ~ " <2
1.2.4-
Tnchloi'iiheii/.eue
(|w:hi
0 0"
()()-
O.ol 14 S
<\o\i:i.i
IDOOIIOII.
|U\. |()S)
1 lie ivasal
adrenal
weiuhls.
\aeunli/alinii
of/una
laseieulala in
llie en lie \
knhmsnii el
al . I'JSI
1). Nnl elassiliable
as in human
eai'eiiKiueuieil>
(l'JS(ii uiudelilies>
() '5
:o"„
0 ()| ( |'N|;||
i4.s(\o\i:i.i
ID	loll.
II) V ins I)|
Increased
adrenal
weiuhls.
\ aeiKili/alinu nl'
/una laseieulala
in I he en lie \
knhiusnu el al .
I'JXI
\nl elassiliable as in
hiiiuau
eareiiKiueiiieil>
(I'JSShi


65 U.S. EPA (2009b) has concluded that 1,2,4-trichlorobenzene is "Likely to be carcinogenic to humans" (2005a guidelines)/ Slope factor 0.029 per mg/kg-
d/POD 3.5 mg/kg-day (BMDLiohed)/ increased hepatocellular carcinoma/0.1/ BMDLiohed
127
-------
Six-Year Review 3	SUMMARY HEALTH EFFECTS ASSESSMENT REPORT	December 2016
Table 39b. Summary of Assessment by Other Organizations: 1,2,4-Trichlorobenzene
CASRN 120-82-1
( homkiil
ATSDR
( iill l'A
WHO
Includes Jl-XTW.
JWK.CICAI). I'.IK
llciillh ( iiiiiithi
N AS
<\e;ir)
IAUC
(\c;ir)
MI.IIS
(jwiri
""" /
<— r, LU S
5 f 3 3 .2
0X3 S ^ 'n ^
o a 2
CL s ~ O
-	^ 5 i J
—	o ~
—
J
"3
cp
e
•j
	 ^
y. —
i. —
— o
'j c-
•—
o
0
£¦
rz — i
D P S? o
r- C >,
w CD ^
.c =
il
_o
O
E—
2
•	
j. —
C3 o
Cj
s—
o
o
0
^ o o
™ ^
'3 y Z C 'i.
a -i* - "
" " .0. ^
o
•j
•	 ^
~ —
I. TZ
rz :j
¦j £¦
o
•J
0
1.2.4-
0.1 (2010c)''-/13.33
~
—
-
~
~
—
~
~
~
Tl'ldllni'lilVll/CllC
(ISMDl.i..)/ 100 (I0A.










lOlli/hcpiilocclliiliir










h\|)or(ni|)h\ in m;ik*










nils/ Mooiv ;il ill. I'm









66 Using the MRL of 0.1 mg/kg/day and assuming 70 kg body weight, 2 L/day water consumption, and a 20% RSC, a potential new MCLG derived from this
value is 0.7 mg/L.
128
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Six-Year Review 3
SUMMARY HEALTH EFFECTS ASSESSMENT REPORT
Table 40a. Summary of EPA Assessments: 1,1,1-Trichloroethane CASRN 71-55-6
December 2016
( lu'iniciil
(l)iilc of
ivuiiliilioni
I .S. I-.PA/OW Niiiioiiiil Priniiin Drinking
Wilier Kouuliilion (\PI)\\ K)
l .S. I-'. PA IRIS
I .S. IP A OPP
CJ
•	
/. —
7 C
Id
_ ^
=P -n-.
= _
w X-
- o I
1 s ? ~
n. o O
^ ° ^5 —
1§ 8
s <3 y *=
^-O LU
9 •= u_ -S-
2 o -j c.
7 "i S 5 5 i-1
1 Mi s 1
— =L -/¦ - ~
J - r 1. 3- =
o b ^ ^
'J. -j 'j " ±
- > - J
C ~ " <2
3 '/¦
-J o£
LU
>
fl^l
cX) •— ^ O
E T3 o
^ ^ ^ cz
— 73 '—
r: O. p UJ
-j j - _
'— — "ZT y
q£ U>
_
2 o s
53 = 5 y E.•a
;/> — s z ^ — o
(/} —
7" <— =L « - T< o
J - r > 3 - =
o b £ a ^
J. -j 'j " —
- > - J
0 ~ <2
ll = 11
CD .= >5 > O
^ O 2 £ ---
«^ = -§ O
— — •— S.J
c: Q. p m
~ O O - —
— -r y.
0£ U.
_
2 o c
;/> z ^ — o
^ zu, r: r? — ^ —
^ ^ (/}
y f" > 3 - =
= > - J
w - -
l.l.l-
1 ndilninelliaiie
(l'JS5hi
u:
u:
IIH'O v* 1
(i.o\i:i.i 		
( Kill. ID V IUI.I
1 lisinlnmcal
changes mi 1 in or
\1c\iill el al .
1T5
1). \m classifiable
as In hiiniaii
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MCLG derived from this value is 14 mg/L.
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Table 41a. Summary of EPA Assessments: 1,1,2-Trichloroethane CASRN 79-00-5
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Table 42a. Summary of EPA Assessments: Xylenes (Total) CASRN 1330-20-7
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Table 42b. Summary of Assessments by Other Organizations: Xylenes (Total)
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APPENDIX C - HEALTH EFFECTS OF FLUORIDE
As a result of the first Six-Year Review of the fluoride NPDWR (67 FR 19030 (U.S. EPA, 2002)
(preliminary); 68 FR 42908 (U.S. EPA, 2003) (final)), EPA requested that the National Research
Council (NRC) of the National Academies of Science (NAS) conduct a review of the health and
exposure data on orally ingested fluoride. In 2006, the NRC published the results of its review in
a report entitled, Fluoride in Drinking Water: A Scientific Review of EPA's Standards. Based on
its review, NRC concluded that severe dental fluorosis is an adverse health effect when it causes
both a thinning and pitting of the enamel, a situation that compromises the function of the
enamel in protecting the tooth from decay and infection. In addition, the committee examined the
scientific data on the impact of fluoride on the strength and structure of bone and the majority
concluded that the MCLG "is not likely to be protective against bone fractures." The NRC
recommended that EPA develop a dose-response assessment for severe dental fluorosis as the
crtitical effect and update an assessment of fluoride exposure from all sources.
During the Six-Year Review 2, the Agency was in the process of developing a dose-response
assessment of the non-cancer impacts of fluoride on severe dental fluorosis and the skeletal
system. In addition, EPA was updating its evaluation of the relative source contribution (RSC) of
drinking water to total fluoride exposure considering the contributions from dental products,
foods, pesticide residues, and other sources such as ambient air and medications. These
assessments were not completed at the time of the Six-Year Review 2; thus, no action was taken
under the Six-Year Review 2 (75 FR 15500, U.S. EPA, 2010c).
In 2010, EPA published fluoride health assessments (U.S. EPA, 2010a; 2010b). In the "Dose
Response Analysis for Non-Cancer Effects" report (U.S. EPA, 2010a), EPA derived a total
reference dose (RfD) of 0.08 milligrams per kilograms per day (mg/kg/day) based on studies of
dental fluorosis among children in the 6 months to 14 year age group (U.S. EPA, 2010a). The
RfD is an estimate of the fluoride dose that will protect against the critical health endpoint -
severe dental fluorosis - as well as clinical stage II skeletal fluorosis and skeletal fractures while
allowing for a fluoride exposure adequate to protect against tooth decay for children and adults.
Confidence in the RfD is considered to be medium because of the challenges of converting
concentration-response data from the Dean (1942) study to dose estimates for the RfD derivation
(U.S. EPA, 2010a). The RfD includes a 0.07 mg/kg/day dose for fluoride in water and 0.01
mg/kg/day for fluoride in food at the time the data on severe dental fluorosis were collected. The
0.07 mg/kg/day dose for fluoride in water was based on a benchmark dose 95 percent lower
bound (BMDL) of 1.87 mg/L that is associated with a 0.5 percent incidence of severe dental
fluorosis in the study by Dean (1942).
In the "Exposure and Relative Source Contribution Analysis" report (U.S. EPA, 2010b), EPA
revised its relative source contribution (RSC) estimates, which range from 40% to 70% across
different age cohorts (U.S. EPA, 2010b). The higher RSC values are associated with infants fed
with powdered formula or concentrate reconstituted with residential tap water {10%) and with
adults (60%>). These RSC values are lower than the RSC of 100%> used to derive the original
MCLG because of the increase in daily exposure to fluoride in other sources such as commercial
beverages, solid foods, fluoride-containing dental products, pesticide residues, and other sources
such as ambient air.
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EPA used the BMDL of 1.87 mg/L as the Drinking Water Equivalent Level for fluoride. The EPA's
(2010b) RSC estimates were derived using the national mean fluoride concentration in public water
supplies at the time of that assessment (0.87 mg/L). Most community water systems (CWSs) that provide
fluoridation of their drinking water have already lowered their fluoridation level to a single level of 0.7
mg/L from a previous range of 0.7 to 1.2 mg/L to accommodate the updated PHS recommendation (U. S.
Department of Health and Human Services, 2015). The U.S. Food and Drug Administration (FDA) also
issued a letter to bottled water manufacturers recommending that they not add fluoride to bottled water in
excess of the revised PHS recommendations (FDA, 2015). In addition, the FDA stated it intends to revise
the quality standard regulation for fluoride added to bottled water to be consistent with the updated PHS
recommendation. Therefore, EPA anticipates that a significant portion of the population's exposure to
fluoride in drinking water, as well as some commercial beverages that use fluoridated water from CWSs
and certain bottled water, has already been or will be reduced. This information will likely be useful in re-
evaluating the RSC. The Six-Year Review 3 monitoring data for fluoride do not reflect the full impact of
the change in the PHS fluoridation level. Therefore, EPA currently cannot use the Six-Year Review 3
monitoring data to project a MCLG based on the RfD at this time. In addition to the tooth and bone
effects, the NRC also evaluated the impact of fluoride on reproduction and development,
neurotoxicity and behavior, the endocrine system, genotoxicity, cancer and other effects. The
NRC (2006) concluded that the available data were inadequate to determine if a risk for effects
on these endpoints exists at an MCLG of 4.0 mg/L and made recommendations for additional
research. After considering the genotoxicity data, cancer studies in humans and animals, and
studies of mode of action in cell systems, the NRC determined that the evidence on the potential
of fluoride to initiate or promote cancers, particularly of the bone, is tentative and mixed. NRC
recommended that EPA await the results and publication of an in-process hospital-based, case-
control study of osteosarcoma and fluoride exposure from the Harvard School of Dental
Medicine before determining if an Agency update of the cancer risk assessment for fluoride is
necessary. One paper from this study (Bassin et al., 2006) was published after the NRC report
but the data were included in the NRC report based on the author's dissertation. Bassin et al.
(2006) showed an age-related relationship between osteosarcoma in young male subjects (< 20
years) and estimated fluoride exposures from drinking water. The NRC classified the study as
having "multiple limitations in design, analysis and presentation of findings." A subsequent
study from the same project (Kim et al., 2011) found there were no significant differences
between the fluoride levels in bone from 142 individuals with osteosarcoma and 52 controls with
cancers at other sites. Two hundred tumor-adjacent bone samples and 57 iliac crest bone samples
were analyzed for their fluoride content. Both conditional and unconditional logistic regressions
were used to analyze the data and determine the odds ratio for a correlation between the bone
fluoride levels and the risk for osteosarcoma. The odds ratio adjusted for age, gender, and a
history of broken bones was 1.33 (CI 0.56-3.15).
Based upon the recommendations of the NRC, EPA has evaluated dental fluorosis as a critical
endpoint of concern for this Six-Year Review (U.S. EPA, 2010a; 2010b). EPA also reviewed
recent publications on the impact of fluoride on reproduction and development, neurotoxicity
and behavior, the endocrine system and cancer as they become available. EPA noted limitations
in some of these studies such as lack of details and confounding factors. Overall, the new data
were not sufficient to alter the NRC conclusion that severe dental fluorosis is the critical health
effects endpoint for the MCLG. While EPA has evaluated the available health effects and
exposure information related to fluoride, the Agency also recognizes that new studies on fluoride
are currently being performed. One example is a National Toxicology Program (NTP) systematic
review of animal studies that examined the impact of fluoride on learning and memory (NTP,
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2016). For more information about fluoride developmental neurotoxicity, visit the National
Toxicology Program website at https://ntp.niehs.nih.gov/pubhealth/hat/noms/fluoride/neuro-
index.html.
Examples of other relevant new studies published after the U.S. EPA (2010a; 2010b) and
NRC (2006) publications are provided below.
•	Blakely et al. (2014) conducted a study to examine whether there was a relationship between
drinking water fluoride and an increased risk of primary bone cancer (osteosarcoma or Ewing
sarcoma). Geographical information system methodologies were used to assign the drinking
water fluoride levels to the cancer cases. The cases were limited to individuals ages birth to
49 years. The findings of Blakely et al. (2014) study provided no evidence that levels of
fluoride (0 to 1.268 mg/L) in drinking water, including systems that fluoridated, lead to
greater risk of either osteosarcoma or Ewing sarcoma. Ewing sarcoma is a tumor that usually
begins in bone or the soft tissue surrounding the bone of children, often during periods of
rapid bone growth.
•	A meta-analysis (Choi et al., 2012) focused on studies conducted in rural China (with
drinking water fluoride concentrations up to 11.5 mg/L) and found an association between
high fluoride exposures and lower IQ scores. The author noted the low quality of the studies
included in the meta-analysis and the inability to rule out other explanations. Another study
by Choi et al. (2015) found that 51 children with moderate or severe dental fluorosis scored
significantly lower in total and backward digit span tests (a test used to assess short-term
memory and working memory) than those with no or questionable fluorosis; 60% of those
tested had moderate or severe dental fluorosis. The authors reported that the levels of other
contaminants that might have neurological impact were low in the area (lead and arsenic
specified), but did not mention the iodine status for the children or the drinking water levels
for manganese. The tests focused on nonverbal measures of learning and memory because
most of the available neurophysiological tests were not in Chinese. Six measures of learning
and memory as represented in 14 subtests were selected. Only one (digit span) displayed a
significant difference between those with normal/questionable fluorosis (n=8) and those with
moderate/severe fluorosis (n=26). The digit span test is described as requiring the child to
repeat a strings of digits forward and backward. Those with moderate/severe dental fluorosis
had significantly lower scores (p<0.05) in the backward and total digit span scores than those
with normal/questionable fluorosis. Although the findings of Choi et al. (2015) are
noteworthy, a limitation of the study is its statistical weight because of the small size of the
study population (n=51), and because of the fact that significance was achieved for only two
components of the 14 subtests administered.
•	Broadbent et al. (2015) conducted a study in New Zealand and reported no association
between high fluoride exposures and lower I.Q. scores in children.
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•	Peckham et al. (2015) reported a higher prevalence of hypothyroidism among primary care
practices located in fluoridated70 versus non-fluoridated areas in England. However, exposure
to fluoridated water was based on the location of the physician's practice, not on the patient's
residence and no attempt was made to control for other confounding factors, such as iodine
sufficiency. Iodine deficiency is common in England (Grimes, 2015).
•	Malin et al. (2015) found a higher prevalence of reported attention deficit hyperactivity
disorder (ADHD) in states with higher percentages of persons receiving fluoridated water.
Exposure to fluoridated water was measured at the state level and based on the CDC census
which includes both naturally fluoridated systems and systems that supplement the natural
fluoride with a certified additive to achieve the fluoride level established by the state for
fluoridation. In addition, the study did not control for other possible factors that may affect
ADHD, such as prenatal exposures to alcohol or tobacco, premature delivery, low birth
weight, and exposure to other environmental factors such as lead.
•	The National Toxicology Program (NTP) conducted a systematic review of animal studies
that examined the impact of fluoride on learning and memory (NTP, 2015; 2016). From
among 4656 studies identified via database searches there were 68 studies in mice and rats
that examined exposures from drinking water or diet; 48 of those studies examined effects on
learning and memory and 16 of those assessed exposures during development. The dose
range tested was 0.12 to 40 mg/kg/day, all greater than the 0.08 mg/kg/day RfD for severe
dental fluorosis in humans identified in the EPA assessment (U.S. EPA, 2010a). NTP (2015;
2016) concluded that there was low to moderate confidence suggestive of effects on learning
and memory with the moderate finding applicable to animals exposed as adults and the low
finding applicable to the developmental studies.
•	A study by Garcia-Perez et al. (2013) strengthens the link between severe dental fluorosis and
carries. The study was conducted in two low socioeconomic communities in Mexico using
457 children (ages 8 -12 years). The mean decayed missing and filled teeth (D3MFT) and the
dental fluorosis score as determined by the Thylstrup-Fejerskov Index (TFI) was highly
significant (P<0.0001) when children (369) with scores< 4 were compared to children with
scores >4 (88). Fluoride exposures were from both the drinking water and salt fluoridation.
Under the TFI procedure scores >4 are those that require pitting of the tooth enamel (U.S.
EPA, 2010a).
References
Bassin, E.B., Wypij D., Davis R.B., Mittleman M.A. 2006. "Age-specific Fluoride Exposure in
Drinking Water and Osteosarcoma." Cancer Causes and Control 17: 421-8.
Blakey, K, Feltbower R, Parslow R, James P, Gomez, Pozo B, Stiller C et al. 2014. Is fluoride a
risk factor for bone cancer? Small area analysis of osteosarcoma and Ewing sarcoma diagnosed
70 EPA's fluoride standard controls for naturally occurring fluoride in drinking water sources. Health data related to
fluoridation is included to provide a comprehensive evaluation of potential health effects associated with fluoride
exposure.
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among 0-49-year-olds in Great Britain, 1980-2005. International Journal of Epidemiology 43:
224-234.
Broadbent, Jonathan M., W. Murray Thomson, Sandhya Ramrakha, Terrie E. Moffitt, Jiaxu
Zeng, Lyndie A. Foster Page, and Richie Poulton. 2015. Community Water Fluoridation and
Intelligence: Prospective Study in New Zealand. American Journal of Public Health 105.1
(2015): 72-76.
Choi, Anna L., Guifan Sun, Ying Zhang, and Philippe Grandjean. 2012. Developmental Fluoride
Neurotoxicity: A Systematic Review and Meta-Analysis. Environmental Health Perspectives
120(10): 1362-368.
Choi, Anna L., Ying Zhang, Guifan Sun, David C. Bellinger, Kanglin Wang, Xiao Jing Yang, Jin
Shu Li, Quanmei Zheng, Yuanli Fu, and Philippe Grandjean. 2015. Association of Lifetime
Exposure to Fluoride and Cognitive Functions in Chinese Children: A Pilot Study.
Neurotoxicology and Teratology 47 (2015): 96-101.
Dean, H.T. 1942. The investigation of physiological effects by the epidemiology method. In:
Fluoride and Dental Health. Publ. Amer. Assoc Advanc. Sci., no. 19, pp. 23-31.
Garcia-Perez, A. Irigoyen-Camacho, M.E., and A. Borges-Yanez. 2013. Fluorosis and dental
carries in schoolchildren residing in areas with different water fluoride concentrations and
receiving fluoridated salt. Carries Research: 47:299-308.
Grimes, D.R. 2015. Commentary on are fluoride levels in drinking water associated with
hypothyroidism prevalence in England? A large observational study of GP practice data and
fluoride levels in drinking water. J Epidemiol Community Health: 69(7): 616.
Kim, F. M., C. Hayes, P. L. Williams, G. M. Whitford, K. J. Joshipura, R. N. Hoover, C. W.
Douglass, M. C. Gebhardt, M. T. Scarborough, S. Gitelis, J. J. Eckardt, J. R. Neff, M. J. Joyce,
M. Malawer, M. Mcguire, and H. C. Anderson. 2011. An Assessment of Bone Fluoride and
Osteosarcoma. Journal of Dental Research 90.10: 1171-176.
Malin, Ashley J., and Christine Till. 2015. Exposure to Fluoridated Water and Attention Deficit
Hyperactivity Disorder Prevalence among Children and Adolescents in the United States: An
Ecological Association. Environmental Health 14:17.
National Research Council. 2006. Fluoride in drinking-water: A Scientific Review of EPA's
Standards. The National Academies Press, Washington D.C.
NTP (National Toxicology Program). 2015. Proposed NTP Evaluation on Fluoride Exposure and
Potential for Developmental Neurobehavioral Effects. Available online at:
https://ntp.niehs.nih.gov/ntp/about ntp/bsc/2015/december/meetinumaterial/fluoride 508.pdf.
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NTP. 2016. Systematic Review of the Effects of Fluoride on Learning and Memory in Animal
Studies. Available online at http s: //ntp .niehs.nih. gov/ntp / oh at/pub s/ntp rr/01 fluoride 5 08. pdf.
Peckham, S., D. Lowery, and S. Spencer. 2015. Are Fluoride Levels in Drinking Water
Associated with Hypothyroidism Prevalence in England? A Large Observational Study of GP
Practice Data and Fluoride Levels in Drinking Water. Journal of Epidemiology and Community
Health 69.7: 619-24.
U.S. EPA. 2002. National Primary Drinking Water Regulations: Long Term 1 Enhanced Surface
Water Treatment Rule. Final Rule. 67 FR 1812. January 14, 2002.
U.S. EPA. 2003. National Primary Drinking Water Regulations; Announcement of the Results of
EPA's Review of Existing Drinking Water Standards and Request for Public Comment and/or
Information on Related Issues. 68 FR 42908. July 18, 2003.
U.S. EPA. 2010a. Fluoride: Dose Response Analysis for Non-Cancer Effects. EPA 820-
R-10-019. December 2010.
U.S. EPA. 2010b. Fluoride: Exposure and Relative Source Contribution Analysis. EPA 820-
R-10-015. December 2010.
U.S. EPA. 2010c. National Primary Drinking Water Regulations; Announcement of the Results
of EPA's Review of Existing Drinking Water Standards and Request for Public Comment and/or
Information on Related Issues. 75 FR 15500. March 29, 2010.
U.S. Food and Drug Administration (FDA). 2015. Letter to Manufacturers, Distributors, or
Importers of Bottled Water with an Update on Fluoride Added to Bottled Water. Available
online at:
http://www.fda.gov/food/guidanceregulation/guidancedocumentsregulatorvinformation/bottledw
atercarbonatedsoftdrinks/ucm444373.htm.
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