Data Sources for the 

Contaminant 

Candidate List 4
Office of Water (4607M) 

EPA 815-R-15-004

January 2015
EPA-OGWDW Data Sources for the 

Contaminant Candidate List 4

EPA 815-R-15-004 

Contents

1.0 Introduction ............................................................................................................................. 1

2.0 Summary of the Process for Evaluating Chemical Data Sources ....................................... 3

3.0 Chemical Data Sources Evaluated for CCL 4 ...................................................................... 4

4.0 Microbial Data Sources Evaluated for CCL 4 ..................................................................... 5

5.0 References ................................................................................................................................ 6

6.0 Appendices ............................................................................................................................ A1

Appendix 1 CCL 4 Data Source Descriptions ........................................................................ A1

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Acronyms and Abbreviations

μ microgram, one 

μg/L micrograms per liter

ATSDR Agency for Toxic Substances and Disease Registry

AWWA American Water Works Association 

CASRN Chemical Abstract Services Registry Number

CDC Centers for Disease Control and Prevention 

CCL Contaminant Candidate List 

CCL 1 EPA’s First Contaminant Candidate List

CCL 2 EPA’s Second Contaminant Candidate List 

CCL 3 EPA’s Third Contaminant Candidate List 

CCL 4 EPA’s Fourth Contaminant Candidate List

CSTE Council of State and Territorial Epidemiologists

CUS/IUR Chemical Update System/Inventory Update Rule

CWSs Community Water Systems

DRI Dietary Reference Intake

EPA United States Environmental Protection Agency 

FDA United States Food and Drug Administration

FR Federal Register

g gram

HHBPs Human Health Benchmark for Pesticides

GAMA California State Water Resources Control Board’s Groundwater Ambient 

Monitoring Assessment 

IARC International Agency for Research on Cancer 

IOM Institute of Medicine

IRIS Integrated Risk Information System 

kg kilogram

L liter

LOAEL Lowest Observed Adverse Effect Level

MCL Maximum Contaminant Level 

MCLG Maximum Contaminant Level Goal

MCM Manual of Clinical Microbiology 

mg/kg milligrams per kilogram body weight 

mg/kg/day milligrams per kilogram body weight per day

mg/L milligrams per liter

MMWR Morbidity and Mortality Weekly Report 

MRL Minimum Risk Level 

NAWQA National Water Quality Assessment

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NCOD National Contaminant Occurrence Database

NDWAC National Drinking Water Advisory Council 

NOAEL No Observed Adverse Effect Level

NREC National Reconnaissance of Emerging Contaminants 

NTP National Toxicology Program 

OEHHA Office of Environmental Health Hazard Assessment 

OPP Office of Pesticide Programs

OSRTI Office of Superfund Remediation and Technology Innovation 

PCCL Preliminary Candidate Contaminant List

PDP Pesticide Data Program

PPCPs Pharmaceuticals and Personal Care Products

PPRTVs Provisional Peer Reviewed Toxicity Values

PWS Public Water System

RDAs Recommended Dietary Allowances

RED Reregistration Eligibility Document

RfC reference concentration

RfD reference dose

RoC Report on Carcinogens 

SDWA Safe Drinking Water Act

STORET EPA's Storage and Retrieval System

SWRCB State Water Resources Control Board

TRI Toxics Release Inventory

ULs Upper Intake Levels

US United States of America

USDA United States Department of Agriculture

USGS United States Geological Survey

WBDO Waterborne Disease Outbreak 

WHO World Health Organization

yr Year

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1.0 Introduction

Section 1412(b)(1) of the Safe Drinking Water Act (SDWA), as amended in 1996, requires EPA 

to publish the Contaminant Candidate List (CCL) every five years. The SDWA specifies that the 

list must include contaminants that are not subject to any proposed or promulgated National 

Primary Drinking Water Regulations (NPDWRs), are known or anticipated to occur in public 

water systems (PWSs) and may require regulation under the SDWA. EPA uses this list of 

unregulated contaminants to help the agency identify priority contaminants for regulatory 

decision making and to prioritize research and data collection efforts. SDWA also requires the 

agency to consult with the scientific community, including the Science Advisory Board and 

provide notice and opportunity for public comment prior to the publication of the Final CCL. In 

addition, SDWA directs the agency to consider the health effects and occurrence information for 

unregulated contaminants to identify those contaminants that present the greatest public health 

concern related to exposure from drinking water. 

EPA published the third CCL (CCL 3), which listed 116 contaminants on October 8, 2009 (74 

FR 51850 (USEPA, 2009a)). In developing the CCL 3, EPA implemented a multi-step process to

select contaminants, which included the following key steps: 

(1) The identification of a broad universe of potential drinking water contaminants (CCL 3 

Universe); 

(2) Screening the CCL 3 Universe to a Preliminary CCL (PCCL) using screening criteria 

based on the potential to occur in PWSs and the potential for public health concern; and

(3) Evaluation of the PCCL contaminants based on a more detailed review of the occurrence 

and health effects data using a scoring and classification system to identify a final list of 

116 CCL 3 contaminants; and 

(4) Incorporating public input and expert review in the CCL 3 process. 

Steps 1, 2 and 3 in the process are described in detail in the CCL 3 support documents: 

• Final CCL 3 Chemicals: Identifying the Universe (USEPA, 2009b);

• Final CCL 3 Chemicals: Screening to a PCCL (USEPA, 2009c);

• Final Contaminant Candidate List 3 Chemicals: Classification of the PCCL to the CCL

(USEPA, 2009d);

• Final CCL 3 Microbes: Identifying the Universe (USEPA, 2009e);

• Final CCL 3 Microbes: Screening to the PCCL (USEPA, 2009f); and

• Final CCL 3 Microbes: PCCL to CCL Process (USEPA, 2009g).

These documents can be found on the EPA web site at: http://www2.epa.gov/ccl/contaminantcandidate-list-3-ccl-3 or at http://www.regulations.gov (docket ID: EPA-HQ-OW-2007-1189). 

After a Final CCL is published, SDWA section 1412(b)(1)(B)(ii) as amended in 1996, requires 

EPA at five year intervals to make determinations of whether to regulate or not to regulate no 

fewer than five contaminants from the CCL in a process called regulatory determinations. This 

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is a separate process from the listing of contaminants on the CCL. The 1996 SDWA 

Amendments specify three criteria to determine whether a contaminant may require regulation: 

• the contaminant may have an adverse effect on the health of persons;

• the contaminant is known to occur or there is a substantial likelihood that the contaminant

will occur in PWSs with a frequency and at levels of public health concern; and

• in the sole judgment of the Administrator, regulation of such contaminant presents a

meaningful opportunity for health risk reduction for persons served by PWSs.

If EPA determines that these three statutory criteria are met and makes a final determination to 

regulate a contaminant, the agency has 24 months to publish a proposed Maximum Contaminant 

Level Goal1 (MCLG) and NPDWR2. After the proposal, the agency has 18 months to publish 

and promulgate a final MCLG and NPDWR (SDWA section 1412(b)(1)(E))3. 

On February 11, 2011, as a separate action, the agency issued a positive regulatory determination 

for perchlorate, a chemical listed in CCL 1, CCL 2 and CCL 3 (76 FR 7762 (USEPA, 2011)). 

Recently, EPA has published preliminary regulatory determinations for five unregulated 

contaminants on the CCL 3 (79 FR 62716 (USEPA, 2014)). The five contaminants include: 

dimethoate; 1,3-dinitrobenzene; strontium; terbufos and terbufos sulfone. The agency is making

preliminary determinations to regulate one contaminant (strontium) and to not regulate four 

contaminants (dimethoate; 1,3-dinitrobenzene; terbufos; and terbufos sulfone). Therefore, the 

agency is removing perchlorate and these five contaminants from the Draft Fourth CCL (CCL 4), 

pending the result of the final regulatory determinations for CCL 3. 

EPA conducted an abbreviated evaluation and selection process for the CCL 4. This abbreviated 

CCL 4 process includes a three pronged approach: (1) carrying forward CCL 3 contaminants 

(minus those with regulatory determinations), (2) seeking and evaluating nominations from the 

public for additional contaminants to consider and (3) evaluating any new data for those 

contaminants with previous negative regulatory determinations from CCL 1 or CCL 2 for 

potential inclusion on the CCL 4. 

As part of the process to develop the CCL 4, EPA published a Federal Register notice (77 FR

27057 (USEPA, 2012)) requesting that the public submit nominations for chemical and 

microbial contaminants to be considered for inclusion in the CCL 4. EPA also requested 

supporting information that has been made available since the development of the CCL 3 or 

existing information that was not considered in the development of the CCL 3, which shows that 

the nominated contaminant may have an adverse health effect on people and occurs or is likely to 

occur in public water systems. EPA reviewed the nominations and supporting information 

provided by nominators to determine if any new data were provided that had not been previously 

1 The MCLG is the "maximum level of a contaminant in drinking water at which no known or anticipated adverse 

effect on the health of persons would occur, and which allows an adequate margin of safety. Maximum contaminant 

level goals are non-enforceable health goals." (40 C.F.R. 141.2; 42 U.S.C. 300g-1) 2 An NPDWR is a legally enforceable standard that applies to public water systems. An NPDWR sets a legal limit 

(called a maximum contaminant level or MCL) or specifies a certain treatment technique (TT) for public water 

systems for a specific contaminant or group of contaminants. The MCL is the highest level of a contaminant that is 

allowed in drinking water and is set as close to the MCLG as feasible using the best available treatment technology 

and analytical methods and taking cost into consideration. 3

 The statute authorizes a nine month extension of this promulgation date. 

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evaluated for CCL 3. The agency also collected additional data for the nominated contaminants, 

when it was available, from both CCL 3 data sources that had been updated and from new data 

sources that were not available at the time of CCL 3. A complete list of references provided by

nominators can be found in the support document Summary of Nominations for the Fourth CCL

(USEPA, 2015). 

The purpose of this document is to provide a description of the data sources that EPA collected 

updated or new information for CCL 4 and to briefly summarize the process, which was 

developed under CCL 3, used to evaluate the new data sources. 

2.0 Summary of the Process for Evaluating Chemical Data Sources

As previously described, EPA collected additional data for the nominated contaminants and 

contaminants with previous negative regulatory determinations (from Regulatory Determinations 

1 & 2), when it was available, from both CCL 3 data sources that had been updated and from 

new data sources that were not available at the time of CCL 3. EPA used the same process 

developed under CCL 3 for evaluating new data sources for potential inclusion in the CCL 4 

process. The process is summarized in this section, and a more detailed description of this 

process can be found in the CCL 3 supporting document: Final CCL 3 Chemicals: Identifying 

the Universe (USEPA, 2009b). 

EPA used four assessment factors (relevance, completeness, redundancy and retrievability) to

evaluate and identify data sources that would be used to make up the CCL 3 Chemical Universe. 

These assessment factors ensure that the data sources are: relevant to the CCL process, complete 

in basic documentation, not redundant with other data sources and are formatted for automated 

retrieval. These factors were based upon the National Drinking Water Advisory Council's

(NDWAC) recommendation that data sources should: 

1. Have data and information about actual or potential occurrence of contaminants in

drinking water or source water and/or about health effects;

2. Focus on readily available data (e.g., those that could be automatically retrieved); and

3. Meet EPA’s minimum guidelines for documentation and quality.

The relevance assessment factor addresses the NDWAC and National Research Council

principles for the CCL 3 Universe and evaluates whether a data source contains information on 

demonstrated or potential occurrence of contaminants in the environment and/or demonstrated or 

potential human health effects. The completeness assessment evaluates whether the data source 

provides complete, minimum documentation and quality requirements. NDWAC recommended 

that each source should include: 1) the name of a person to contact about the data source (or 

contact information); 2) a description of the data elements; 3) information on how the data were 

obtained; and 4) meaningfulness and relevance of the data. The “meaningfulness and relevance” 

NDWAC recommendation is addressed by the relevance assessment factor, so it is not included 

in the completeness assessment. Also, data sources that provide documentation of peer review 

are considered to satisfy the completeness criteria. The redundancy assessment factor evaluates 

whether data sources contain information that is identical to (i.e., duplicate information) other, 

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more comprehensive data sources. An example of a redundant source would be data contained in 

a state or regional data source that were copied from a more comprehensive or representative 

national data source. Therefore, to be considered redundant, a data source must contain data 

identical with respect to the identity of the original data gatherer, time, place, method, outcome 

and data manipulation or modification. The retrievability assessment factor is an evaluation of 

whether the data in a source are formatted for automated retrieval. For example, if data are stored 

in a tabular format, they may be extracted and formatted using software tools and imported 

directly into a database for further use.

Each data source was accessed online (or as provided by the source proprietor) and reviewed. 

Basic information about the data source, its purpose and the data elements it contained was 

compiled and documented. Every source was evaluated using all four assessment factors. For a 

complete list and description of the 40 primary data sources and 64 supplemental data sources 

used for CCL 3, please refer to Final CCL 3 Chemicals: Identifying the Universe (USEPA, 

2009b). 

3.0 Chemical Data Sources Evaluated for CCL 4

This section lists both the chemical data sources that were used for CCL 3 and were updated for 

CCL 4 and the new data sources evaluated for CCL 4 that were not available at the time of CCL 

3. EPA evaluated each of the new data sources for CCL 4 according to the four assessment

factors that are described in Section 2. A more detailed description of each of these data sources

including an explanation of whether the new data sources met each of the four assessment factors 

can be found in Appendix 1. 

Occurrence data was collected from updated CCL 3 data sources including: 

• 2006 production data collected in the Chemical Update System (CUS) under the

Inventory Update Rule (IUR),

• 2010 data from the Toxics Release Inventory (TRI),

• 2003-2009 data from the U.S. Department of Agriculture’s (USDA) Pesticide Data

Program (PDP), and

• EPA’s Storage and Retrieval (STORET) data as of January 2013.

Additional occurrence data for the nominated contaminants were collected from data sources that 

are new since the CCL 3 including: 

• USGS studies that focused on contaminant occurrence in source waters for public water

systems (Hopple et al., 2009, and Kingsbury et al., 2008) and water quality in publicsupply wells (Toccalino et al., 2010);

• Individual State public water supply data provided to EPA during the second Six-Year

Review of regulated contaminants (for the time period covering 1998-2005) from States

including: CA, FL, IL, NC, OH, Region 9 Tribes, SD, TX and WI;

• Data from the California State Water Resources Control Board’s Groundwater Ambient

Monitoring Assessment (GAMA) program; and

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• New data from a literature review of published studies on pharmaceuticals, personal care

products and other contaminants.

In addition to health effects data provided by the nominators, EPA searched for health effects 

data for the nominated contaminants from data sources used in CCL 3 that may have been 

updated including: 

• EPA’s Integrated Risk Information System (IRIS) program,

• EPA’s Office of Pesticide Programs (OPP),

• Agency for Toxic Substances and Disease Registry (ATSDR),

• California EPA (Office of Environmental Health Hazard Assessment),

• Institute of Medicine (IOM),

• National Toxicology Program (NTP), and

• World Health Organization (WHO).

EPA also considered new or updated health effects information contained in the agency’s Office 

of Superfund Remediation and Technology Innovation (OSRTI) Provisional Peer Reviewed 

Toxicity Values (PPRTVs). 

4.0 Microbial Data Sources Evaluated for CCL 4

This section outlines the data sources and approaches used to develop the microbial CCL from 

the Universe through the final CCL. Because of the inherent differences between microbes and 

chemicals and differences in the availability of tabulated data containing the data elements 

required for screening evaluations, it was necessary to rely upon text-based resources for 

processing microbes.

The Microbial CCL 3 Universe was defined as all known human pathogens and the compilation 

of Taylor et al. (2001) served as a practical starting point. This list includes 1,415 bacteria, 

viruses, protozoa, helminths and fungi known to be pathogenic for humans based upon literature 

review. This list was supplemented by adding six fungi isolated from drinking water distribution 

systems that did not appear on the Taylor list and with 2 nominations from the scientific 

community (from CCL 3). Since the publication of CCL 3, there have been no updates to Taylor 

et al. (2001), so the CCL 3 Universe is being carried forward to the Draft CCL 4. 

During CCL 3, text-based resource materials, such as The Manual of Clinical Microbiology 

(MCM), 9th Edition, were used to inform the screening and scoring process. The MCM 10th 

edition was published in 2011 (MCM, 2011). The MCM is a two-volume peer reviewed 

reference that is written by an international team of subject experts. EPA reviewed the latest 

edition of the MCM for changes that would affect the outcome of the nominated microbes in 

CCL 4. No new data were found that would result in a different outcome for any of the 

nominated microbes. 

For CCL 3, web searches were also conducted to identify authoritative online databases which 

could be used to document screening decisions (e.g., Universe to PCCL). While it is possible that 

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these sources may contain updated information regarding nomenclature or classification, new 

data detailing a fundamental change in characteristics were not found for use in CCL 4. Thus, the 

criteria used for exclusion of microbes during CCL 3 remain valid. For more information on the 

screening criteria developed under CCL 3 and used for CCL 4, please see Final Contaminant 

Candidate List 3 Microbes: Screening to the PCCL (USEPA, 2009f). 

The MCM (2011) was one of the main sources of information used to inform the scoring of the 

PCCL microbes (both for CCL3 and CCL4). EPA also conducted a literature search covering the 

time period between CCL 3 and CCL 4 (2007-2012). The literature search focused on health 

effects and occurrence of the nominated microbial contaminants in water. No new data were 

found as a result of the literature search that would support a change to the CCL 3 scores, thus 

the scores remain the same for CCL 4. For more information on the scoring protocols developed 

under CCL 3 and used for CCL 4, please see Final Contaminant Candidate List 3 Microbes: 

PCCL to CCL Process (USEPA, 2009g). 

For Waterborne Disease Outbreaks (WBDOs), the primary source for scoring data was the 

Center for Disease Control (CDC) Morbidity and Mortality Weekly Reports (MMWR). CDC, 

EPA and the Council of State and Territorial Epidemiologists (CSTE) maintain a collaborative 

surveillance system for collecting and periodically reporting data related to occurrences and 

causes of WBDOs. These reports from the CDC are published periodically in the MMWR. For 

the CCL 3, EPA used CDC’s MMWR summaries from 1998-2004 as the source for the WBDO 

scoring protocol. The same process was used for CCL 4, however the data were updated through 

2008 (CDC, 2008; CDC, 2011). 

5.0 References

CDC. 2008. Surveillance for Waterborne Disease and Outbreaks Associated with Drinking 

Water and Water not Intended for Drinking — United States, 2005-2006. MMWR 57 (SS-9); 1-

72 (Table 4, p. 45; Table 5 p. 46). 

CDC. 2011. Surveillance for Waterborne Disease and Outbreaks Associated with Drinking 

Water - United States, 2007-2008. MMWR 60 (SS-12); 1-80 (Table 4, p. 45; Table 5 p. 46). 

Murray, P. R., E. J. Baron, J. H. Jorgensen, M. A. Pfaller, and R. H Yolken (ed.) The Manual of 

Clinical Microbiology, 10th edition, American Society for Microbiology, Washington, DC Vol. 

2; pp. 3129. 

Taylor, L. H., S. M. Latham, and M. E. Woolhouse. 2001. Risk factors for human disease 

emergence Philosophical Transactions of the Royal Society of London B. Vol. 356, pp. 983-989 

USEPA. 2009a. Drinking Water Contaminant Candidate List 3—Final Notice. Federal Register. 

Vol. 74. No 194. p.51850, October 18, 2009. 

USEPA, 2009b. Final Contaminant Candidate List 3 Chemicals: Identifying the Universe. EPA. 

815-R-09-006. August 2009. 

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USEPA, 2009c. Final Contaminant Candidate List 3 Chemicals: Screening to a PCCL. EPA 815-

R-09-007. August 2009. 

USEPA, 2009d. Final Contaminant Candidate List 3 Chemicals: Classification of PCCL to the 

CCL. EPA 815-R-09-008. August 2009. 

USEPA, 2009e. Final Contaminant Candidate List 3 Microbes: Identifying the Universe. EPA 

815-R-09-008. August 2009. 

USEPA, 2009f. Final Contaminant Candidate List 3 Microbes: Screening to the PCCL. EPA 

815-R-09-008. August 2009. 

USEPA, 2009g. Final Contaminant Candidate List 3 Microbes: PCCL to CCL Process. EPA 

815-R-09-009. August 2009. 

USEPA, 2012. Request for Nominations of Drinking Water Contaminants for the Fourth 

Contaminant Candidate List. Federal Register Vol. 77. No 89. p. 27057, May 8, 2012. 

USEPA. 2014. Announcement of Preliminary Regulatory Determination for Contaminants on 

the Third Drinking Water Contaminant Candidate List. Federal Register. Vol. 79, No. 202, p. 

62716, October 20, 2014. 

USEPA, 2015. Summary of Nominations for the Fourth Contaminant Candidate List. EPA 

815 R-15-001. January, 2015.

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6.0 Appendices

Appendix 1. CCL 4 Data Source Descriptions

Appendix 1 lists the data sources evaluated for CCL 4 including both CCL 3 data sources that 

had been updated and new data sources that were not available at the time of CCL 3. This 

appendix provides a brief description of each dasta source, gives the proprietor information, 

contact information, type of data elements contained in the data source, provides an explanation 

of whether each data source meets the four assessment factors and provides a source URL, if 

applicable.

Data Sources for Chemical Contaminants

Data Source Name 12th Report on Carcinogens - NTP

Data Source Description The Report on Carcinogens (RoC) is a congressionally-mandated 

document that is prepared by the National Toxicology Program (NTP) for 

the Secretary of the U.S. Department of Health and Human Services. 

The RoC is updated periodically, and the 12th RoC (released in 2011) 

contains profiles for 240 substances, including 54 substances that are 

known to be human carcinogens and 186 substances that are 

reasonably anticipated to be human carcinogens. The substance profiles 

contain data regarding carcinogenicity, genotoxicity, mechanisms of 

action in people and/or in animals, the potential for human exposure to 

these substances, federal regulations to limit exposures, 

physical/chemical properties, use and production. (Description adapted 

from website.)

Proprietor National Toxicology Program, National Institute of Environmental Health 

Sciences

Contact Information Dr. Ruth M. Lunn 

Director, Report on Carcinogens Center

National Toxicology Program 

Mailing Address: MD K2-14, P.O. Box 12233

Research Triangle Park, NC 27709

Courier Address: 530 Davis Drive, Room 2006

Morrisville, NC 27560 T

Phone: (919) 316-4637

Fax: (919) 541-0144 

Email: lunn@niehs.nih.gov

Type of Data Elements Name, CASRN, International Agency for Research on Cancer (IARC) 

cancer class, toxicological study data, molecular weight, specific gravity, 

vapor pressure, vapor density, Melting Point, Boiling Point, log Kow, 

dissociation constant, use, production, critical effect, exposure potential, 

releases, occupational exposure limits 

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Relevance Explanation This source is considered relevant for the CCL Universe because it 

contains data elements from toxicological studies.

Completeness Explanation It meets considerations because it is peer reviewed.

Redundancy Explanation This source is not redundant.

Retrievability Explanation This source does not meet retrievability criteria because the data are not 

formatted for automated retrieval.

Source URL http://ntp.niehs.nih.gov/?objectid=03C9AF75-E1BF-FF40-

DBA9EC0928DF8B15

Data Source Name Agency for Toxics Substances and Disease Registry Minimal 

Risk Levels (MRLs)

Data Source Description The ATSDR Minimal Risk Levels (MRLs) were developed as an initial 

response to Congressional mandate. Following discussions with 

scientists within the Department of Health and Human Services (HHS) 

and the EPA, ATSDR chose to adopt a practice similar to that of the 

EPA's Reference Dose (RfD) and Reference Concentration (RfC) used 

for deriving substance-specific health guidance levels for non-neoplastic 

endpoints. An MRL is an estimate of the daily human exposure to a 

hazardous substance that is likely to be without appreciable risk of 

adverse noncancer health effects over a specified duration of exposure. 

These substance-specific estimates, which are intended to serve as 

screening levels, are used by ATSDR health assessors and other 

responders to identify contaminants and potential health effects that may 

be of concern at hazardous waste sites. It is important to note that MRLs 

are not intended to define clean-up or action levels for ATSDR or other 

Agencies. 

During the development of toxicological profiles, MRLs are derived when 

ATSDR determines that reliable and sufficient data exist to identify the 

target organ(s) effected or the most sensitive health effect(s) for a 

specific duration for a given route of exposure to the substance. MRLs 

are based on noncancer health effects only and are not based on a 

consideration of cancer effects. Inhalation MRLs are exposure 

concentrations expressed in units of parts per million (ppm) for gases 

and volatiles or milligrams per cubic meter (mg/m3) for particles. Oral 

MRLs are expressed as daily human doses in units of milligrams per 

kilogram per day (mg/kg/day). Radiation MRLs are expressed as 

external exposures in units of millisieverts.

ATSDR uses the no-observed-adverse-effect-level/uncertainty factor 

(NOAEL/UF) approach to derive MRLs for hazardous substances. They 

are set below levels that, based on current information, might cause 

adverse health effects in the people most sensitive to such substanceinduced effects. MRLs are derived for acute (1-14 days), intermediate 

(>14-364 days), and chronic (365 days and longer) exposure durations, 

and for the oral and inhalation routes of exposure. Currently MRLs for 

the dermal route of exposure are not derived because ATSDR has not 

yet identified a method suitable for this route of exposure. MRLs are 

generally based on the most sensitive substance-induced end point 

considered to be of relevance to humans. ATSDR does not use serious 

health effects (such as irreparable damage to the liver or kidneys, or birth 

defects) as a basis for establishing MRLs. Exposure to a level above the 

MRL does not mean that adverse health effects will occur.

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Proposed MRLs undergo a rigorous review process. They are reviewed 

by the Health Effects/MRL Workgroup within the Division of Toxicology; 

an expert panel of external peer reviewers; the agency wide MRL 

Workgroup, with participation from other federal agencies, including 

EPA; and are submitted for public comment through the toxicological 

profile public comment period. Each MRL is subject to change as new 

information becomes available concurrently with updating the 

toxicological profile of the substance. MRLs in the most recent 

toxicological profiles supersede previously published levels. As of the 

date last accessed for CCL update, 120 inhalation MRLs, 189 oral MRLs 

and 6 external radiation MRLs have been derived. (Description adapted 

from website.)

Proprietor Agency for Toxic Substances and Disease Registry

Contact Information Dr. Selene Chou

Division of Toxicology

Agency for Toxic Substances and Disease Registry

1600 Clifton Road, Mailstop E29

Atlanta, Georgia 30333Telephone: 404-498-0705 

E-Mail: cjc3@cdc.gov

Type of Data Elements Name, CASRN, MRL (chronic, intermediate, acute)

Relevance Explanation This source is considered relevant for the CCL Universe because it 

contains data elements (MRL) derived from toxicological studies.

Completeness Explanation It meets considerations because it is peer reviewed.

Redundancy Explanation These data are also represented in the ATSDR Toxicological Profiles; 

however, these data are tabular while the Profiles are monographic.

Retrievability Explanation This source meets retrievability criteria because it is in tabular format.

Source URL http://www.atsdr.cdc.gov/mrls/index.html

Data Source Name Background document for development of WHO Guidelines 

for Drinking-water Quality

Data Source Description The fourth edition of the World Health Organization’s Guidelines for 

Drinking-water Quality are intended to support the development and 

implementation of risk management strategies that will ensure the safety 

of drinking-water supplies through the control of hazardous constituents 

of water. WHO has been issuing drinking water guidelines for over 50 

years.

WHO informs the public through the establishment of health-based 

targets, catchment-to-consumer water safety plans and independent 

surveillance. The first WHO document dealing specifically with public 

drinking-water quality was published in 1958 as International Standards 

for Drinking-water and was revised in 1963 and in 1971. In 1984–1985, 

the first edition of the WHO Guidelines for Drinking-water Quality 

(GDWQ) was published in three volumes. Second editions of these 

volumes were published in 1993, 1996 and 1997. Addenda to Volumes 1 

and 2 of the second edition were published in 1998 addressing selected 

chemicals. An addendum on microbiological aspects reviewing selected 

microorganisms was published in 2002. The third edition of the GDWQ 

was published in 2004, the first addendum to the third edition was 

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published in 2006 and the second addendum to the third edition was 

published in 2008. The fourth edition was published in 2011.

The GDWQ are subject to a rolling revision process. Through this 

process, microbial, chemical and radiological aspects of drinking-water 

are subject to periodic review and documentation related to aspects of 

protection and control of public drinking water quality is accordingly 

prepared and updated. (Description adapted from website and document 

introduction.)

Proprietor World Health Organization

Contact Information World Health Organization

Avenue Appia 20

1211 Geneva 27

Switzerland

Telephone: + 41 22 791 21 11

Facsimile (fax): + 41 22 791 31 11

Type of Data Elements Name, CASRN, chemical properties, concentration data, guideline value, 

Tolerable Daily Intake, NOAEL

Relevance Explanation This source is considered relevant for the CCL Universe because it 

contains data elements from toxicological studies.

Completeness Explanation It meets considerations because it is peer reviewed.

Redundancy Explanation This source is not redundant.

Retrievability Explanation This source does not meet retrievability criteria because the data are not 

formatted for automated retrieval.

Source URL http://www.who.int/water_sanitation_health/dwq/guidelines/en/

Data Source Name California EPA Office of Environmental Health Hazard 

Assessment (OEHHA)

Data Source Description The Toxicity Criteria Database from California EPA OEHHA contains 

information on over 260 chemicals. The database reports information 

that includes the following: cancer potency information (oral/inhalation 

slope factors), chronic and acute Reference Exposure Levels (RELs), 

California Public Health Goals (CPHG), California Proposition 65 No 

Significant Risk Levels (NSRLs) and Maximum Allowable Daily Levels 

(MADLs).The “Technical Support Document for Describing Available 

Cancer Potency Factors (TSD)” contains cancer unit risks and potency 

factors for 121 of the 201 carcinogenic substances or groups of 

substances for which emissions must be quantified in the Air Toxics Hot 

Spots program. The purpose of this document is to provide a summary of 

the data supporting the carcinogenic potential of the substance or group 

of substances and to provide the calculation procedure used to derive 

the estimated unit risk and cancer potency factors. For the complete 

document, go to: http://www.oehha.ca.gov/air/cancer_guide/TSD2.html 

to download. No new data was identified for use in CCL 4. (Description 

adapted from website.)

Proprietor California Office of Environmental Health Hazard Assessment

Contact Information Office of Environmental Health Hazard Assessment

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California Environmental Protection Agency

1515 Clay Street, 16th Floor

Oakland, California 94612

(510) 622-3200

Type of Data Elements Critical effect, CAMCL, CAPHG, cancer risk, cancer groups, MADL, 

NSRL, REL, slope factor, unit risk

Relevance Explanation This source is considered relevant for the CCL Universe because it 

contains data elements derived from toxicological studies.

Completeness Explanation It meets considerations because it is peer reviewed.

Redundancy Explanation This source is not redundant.

Retrievability Explanation This source meets retrievability criteria because it is in tabular format

Source URL http://www.oehha.ca.gov/risk/ChemicalDB/index.asp

Data Source Name Chemical Update System (CUS)/Inventory Update Reporting 

(IUR) rule

Data Source Description The Chemical Update System (CUS) database contains confidential data 

reported by industry (approximately 1,200 companies) as a partial 

update of the Toxic Substances Control Act (TSCA) Inventory. Data 

reported under the Inventory Update Reporting (IUR) rule were stored in 

the CUS database. Under the IUR, manufacturers and importers were 

required to report company information (e.g., plant site name, address

and Data Universal Numbering System (DUNS) number) and chemical 

information (e.g., CAS registry number, Premanufactures Number 

(PMN)/Bonafide/Test Marketing Exemption Application (TMEA) or 

Confidential Chemicals Identification (CCID) System Assession Number 

and production volume) for chemicals they manufactured or imported in 

excess of 25,000 pounds (up from 10,000 pounds in 2002) in the 

previous fiscal year. U.S. Environmental Protection Agency (EPA) 

released the 2006 IUR rule (currently called the Chemical Data 

Reporting (CDR) rule) information on more than 6,200 chemicals in 

commerce. EPA had previously compiled the 1998 and 2002 IUR data 

for CCL 3. EPA downloaded the 2006 IUR data in August, 2010 for use 

in CCL 4. The CUS database contains comprehensive use and exposure 

information on the most widely used chemicals in the United States. 

(Description adapted from website.)

Proprietor EPA

Contact Information E-mail: TSCA Hotline (tsca-hotline@epamail.epa.gov) 

TSCA Hotline Phone: 202-554-1404 

IUR/CDR Helpline Phone: 202-564-3012

Type of Data Elements Production Volume

Relevance Explanation This source is considered relevant for the CCL Universe because it 

contains information on production volume, which may indicate potential 

occurrence.

Completeness Explanation It meets considerations because it meets all NDWAC minimum data 

requirements.

Redundancy Explanation This source is not redundant.

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Retrievability Explanation This source meets retrievability criteria because it is in tabular format.

Source URL http://www.epa.gov/cdr/

Data Source Name Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, 

Boron, Chromium, Copper, Iodine, Iron, Manganese, 

Molybdenum, Nickel, Silicon, Vanadium, and Zinc - Institute 

of Medicine

Data Source Description This volume is from a series issued by the National Academy of 

Sciences on dietary reference intakes (DRIs). This series provides 

recommended intakes, such as Recommended Dietary Allowances 

(RDAs) and Tolerable Upper Intake Levels (ULs), for maintaining 

nutritionally adequate diets for individuals in the United States and 

Canada based on factors such as age and gender. In addition, the ULs 

will help a consumer know how much is "too much" of a nutrient. 

Recommendations have been made for the following: vitamins A and K, 

iron, iodine, chromium, copper, manganese, molybdenum, zinc and other 

potentially beneficial trace elements such as boron to determine the 

roles, if any, they play in health. (Description adapted from website.)

Proprietor National Academy of Sciences – Institute of Medicine

Contact Information Geraldine Kennedo

Administrative Assistant, Food and Nutrition Board

Phone: 202-334-1732 

Fax: 202-334-2316

E-mail:gkennedo@nas.edu

Keck Center

W700

500 Fifth St. NW

Washington, DC 20001

Type of Data Elements Name, DRIs, RDAs, ULs.

Relevance Explanation This source is considered relevant for the CCL Universe because it 

contains data elements from toxicological studies.

Completeness Explanation It meets considerations because it is peer reviewed.

Redundancy Explanation This source is not redundant.

Retrievability Explanation This source does not meet retrievability criteria because the data are not 

formatted for automated retrieval. However, this source was only used 

for the UL for manganese, thus retrievability was not an issue.

Source URL http://www.iom.edu/Reports/2001/Dietary-Reference-Intakes-for-VitaminA-Vitamin-K-Arsenic-Boron-Chromium-Copper-Iodine-Iron-ManganeseMolybdenum-Nickel-Silicon-Vanadium-and-Zinc.aspx

Data Source Name EPA Office of Water Literature Search for Supplemental Water 

Occurrence Data for Pharmaceuticals, Personal Care 

Products and Other Contaminants

Data Source Description As part of its ongoing assessment of pharmaceuticals in the 

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environment, and particularly in water, the USEPA Office of Water’s, 

Office of Science and Technology has been conducting a search and 

review of peer-reviewed, published journal literature for studies dealing 

with the occurrence of pharmaceuticals and personal care products 

(PPCPs) in the environment. The literature review included 171 papers 

that were published between 2001 through 2010. For CCL 4, EPA 

reviewed the literature found in the search to identify papers that present 

supplemental occurrence data for ambient water or drinking water that 

were not previously considered under CCL 3. Many of the studies were 

highly localized in scope, so were only evaluated as supplemental data if 

other more comprehensive studies were not available. Many of the 

studies involved waste waters and media other than water and these 

were not used for CCL 4. The Office of Ground Water and Drinking 

Water, to supplement the journal literature, reviewed 14 studies 

published by the USGS since CCL 3 (since late 2008) on PPCPs and 

other contaminants for possible additional supplemental data 

(http://toxics.usgs.gov/). 

Proprietor U.S. EPA

Contact Information Octavia Conerly 

USEPA – Office of Science and Technology

Email: conerly.octavia@epa.gov

Meredith Russell

USEPA- Office of Ground Water and Drinking Water

Email: russell.meredith@epa.gov

Type of Data Elements Measured contaminant concentrations from water samples, number of 

samples and/or sites with samples, number of detections, type of sites 

and samples, etc.

Relevance Explanation This source is considered relevant for the CCL Universe because it 

contains data elements for supplemental contaminant occurrence in 

water, which may indicate potential occurrence in drinking water.

Completeness Explanation It meets considerations because the studies were peer-reviewed. 

Redundancy Explanation This source is not redundant though some, but not all, data may overlap 

among papers by the same authors. This source may also overlap with 

prior published USGS reports and the NAWQA and NREC data, 

collected for CCL 3. 

Retrievability Explanation Data not retrievable. This source contains tabulated occurrence data that 

can be copied and formatted. 

Source URL Not applicable

Data Source Name Groundwater Ambient Monitoring and Assessment (GAMA) 

Program

Data Source Description The GAMA Program is California's comprehensive groundwater quality 

monitoring program conducted cooperatively with USGS. The GAMA 

data used in this analysis are from water samples from public drinking 

water supply wells (i.e., untreated “source water”). Major groundwater 

supply basins are a specific focus of the GAMA program. The main goals 

of the program are to improve statewide groundwater monitoring and to 

increase the availability of groundwater quality information to the public. 

GAMA collects data by testing the untreated or raw water in different 

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types of wells for naturally-occurring and man-made chemicals. In 2000 

the State Water Resources Control Board (SWRCB) created the ambient 

monitoring program to better understand California’s groundwater quality 

issues. The GAMA Program was later expanded, resulting in a plan to 

monitor and assess groundwater quality in basins that account for over 

95% of the state’s groundwater use. GAMA Program projects have 

analyzed thousands of water samples for hundreds of chemicals – many 

of the chemicals at ultra-low detection limits requiring state-of-the-art 

facilities and methods. GAMA compiles these test results with existing 

groundwater quality data from several agencies into a publicly-accessible 

internet database, GeoTracker GAMA. There are four active GAMA 

projects: Priority Basin Project, Domestic Well Project, Special Studies 

Project, and GeoTracker GAMA.

Proprietor California State Water Resources Control Board (SWRCB)/U.S. 

Geological Survey (USGS)

Contact Information John Borkovich

jborkovich@waterboards.ca.gov

GAMA Program Manager

916-341-5779

Type of Data Elements Drinking water (source water) occurrence concentrations

Relevance Explanation This source is considered relevant for the CCL Universe because it 

contains measurements of contaminants in water, demonstrating 

occurrence.

Completeness Explanation This source meets completeness considerations because it meets all 

NDWAC minimum data requirements.

Redundancy Explanation This source is not redundant.

Retrievability Explanation This source contains tabulated occurrence data that can be downloaded 

and analyzed.

Source URL http://www.waterboards.ca.gov/gama/

Data Source Name Hopple, et al., 2009. Anthropogenic Organic Compounds in 

Source Water of Selected Community Water Systems that 

Use Groundwater, 2002–05 - USGS

Data Source Description As part of the NAWQA program, Hopple et al. (2009) conducted studies 

to analyze 258 anthropogenic organic compounds in groundwater used 

as source waters for community water systems (CWSs). Most of the 258 

compounds analyzed are unregulated in drinking water. In Phase 1 of 

the sampling, source water samples were collected between October 

2002 and July 2005 from 221 wells that withdraw from 12 aquifers across 

the U.S. In Phase 2 of the sampling, USGS collected source and finished 

water samples from 94 wells at selected CWSs between June 2004 and 

September 2005. These samples were analyzed for a smaller subset of 

compounds, which occurred most frequently, or were found at relatively 

high concentrations in Phase 1 of the sampling. 

Reference: Hopple, J.A., Delzer, G.C., and Kingsbury, J.A., 2009, 

Anthropogenic organic compounds in source water of selected 

community water systems that use groundwater, 2002–05: U.S. 

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Geological Survey Scientific Investigations Report 2009–5200, 74 p.

Proprietor United States Geological Survey (USGS)

Contact Information Director, USGS South Dakota Water Science Center

1608 Mt. View Rd.

Rapid City, SD 57702

Phone: (605) 394–3200 

Web: http://sd.water.usgs.gov

Email: dc_sd@usgs.gov

Type of Data Elements Measured contaminant concentrations from water samples, number of 

samples/sites with samples, number of detections, etc.

Relevance Explanation This source is considered relevant for the CCL Universe because it 

contains data elements for contaminant occurrence in source water 

obtained from ground water resources.

Completeness Explanation It meets all considerations because it is peer reviewed.

Redundancy Explanation This source is not redundant though some, but not all, data may overlap 

with Toccalino et al. and with the NAWQA database analyzed separately 

for CCL 3.

Retrievability Explanation This source contains tabulated occurrence data that can be copied and 

formatted.

Source URL http://pubs.usgs.gov/sir/2009/5200/

Data Source Name Integrated Risk Information System (IRIS)

Data Source Description EPA’s IRIS Program is a human health assessment program that 

evaluates quantitative and qualitative risk information on effects that may 

result from exposure to chemical substances found in the environment. 

Through the IRIS Program, EPA provides the highest quality sciencebased human health assessments to support the agency’s regulatory 

activities. The IRIS database contains information for more than 550 

chemical substances that can be used to support the first two steps 

(hazard identification and dose-response evaluation) of the risk 

assessment process. When supported by available data, IRIS provides 

toxicity values and qualitative information for chronic cancer and 

noncancer health effects, including: 

• Noncancer effects: Oral reference doses and inhalation reference

concentrations (RfDs and RfCs, respectively) for effects known or 

assumed to be produced through a nonlinear (possibly threshold) 

mode of action. In most instances, RfDs and RfCs are developed for 

the noncarcinogenic effects of substances.

• Cancer effects: Descriptors that characterize the weight of evidence

for human carcinogenicity, oral slope factors, and oral and inhalation

unit risks for carcinogenic effects. Where a nonlinear mode of action

is established, RfD and RfC values may be used.

Government and private entities use IRIS by combining IRIS toxicity 

values with specific exposure information to help characterize public 

health risks of chemical substances and thereby support risk 

management decisions designed to protect public health.

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Proprietor EPA Office of Research and Development; ORD, National Center for 

Environmental Assessment

Contact Information U.S. EPA Risk Information Hotline at telephone 1-301-345-2870, or fax 

to 1-301-345-2876, or

by email to Hotline.IRIS@epamail.epa.gov

Type of Data Elements Name, Synonyms, CASRN, RfC, RfD, SF(i,o), UR(i,o), NO(A)EL, 

LO(A)EL, Benchmark Concentration/ Dose (BMC/D), Benchmark Dose 

Limit (BMDL), Critical effect

Relevance Explanation This source is considered relevant for the CCL Universe because it 

contains data elements from toxicological studies.

Completeness Explanation It meets all considerations because it is peer reviewed.

Redundancy Explanation For CCL 4, IRIS is available electronically and retrievable. During CCL 3, 

the toxicological data for IRIS were available in tabular format from ITER 

(data source #110) and RAIS-Health Effects (data source #178) (see 

USEPA, 2009b. Final Contaminant Candidate List 3 Chemicals: 

Identifying the Universe.) Hence, there is some overlap and redundancy 

but each also provides additional information not available elsewhere.)

Retrievability Explanation For CCL 4, IRIS is available electronically and retrievable. During CCL 3 

this source contained monographs that were not formatted for automated 

retrieval. However, the toxicological data from this source have been 

compiled for electronic retrieval in ITER and were obtained from there for 

CCL 3. IRIS monographs were used to confirm the IRIS/ITER data.

Source URL http://www.epa.gov/iris/index.html

Data Source Name Kingsbury, et al., 2008. Anthropogenic Organic Compounds 

in Source Water of Nine Community Water Systems that 

Withdraw from Streams, 2002–05 - USGS

Data Source Description As part of the NAWQA program, Kingsbury et al. (2008) conducted 

studies to analyze 258 anthropogenic organic compounds in surface 

waters used as source waters for nine CWSs. In Phase 1 of the studies, 

source water samples were collected between 2002 and 2004 from nine 

CWSs served by streams across the U.S. In Phase 2 of the studies, 

USGS collected source and finished water samples at eight of the nine 

CWSs between 2004 and 2005. 

Reference: Kingsbury, J.A., Delzer, G.C., and Hopple, J.A., 2008, 

Anthropogenic organic compounds in source water of nine community 

water systems that withdraw from streams, 2002–05: U.S. Geological 

Survey Scientific Investigations Report 2008–5208, 66 p.

Proprietor United States Geological Survey (USGS)

Contact Information Director, USGS South Dakota Water Science Center

1608 Mt. View Rd.

Rapid City, SD 57702

Phone: (605) 394–3200 

Web: http://sd.water.usgs.gov Email: dc_sd@usgs.gov

Type of Data Elements Water occurrence data elements, measured concentrations, number of 

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sites, number of detections, etc.

Relevance Explanation This source is considered relevant for the CCL Universe because it 

contains data elements for contaminant occurrence in source water 

obtained from surface water resources.

Completeness Explanation It meets all considerations because it is peer reviewed.

Redundancy Explanation This source is not redundant (though some, but not all, data may overlap 

with the NAWQA database analyzed separately for CCL 3).

Retrievability Explanation This source contains tabulated occurrence data that can be copied and 

formatted.

Source URL http://pubs.usgs.gov/sir/2008/5208/

Data Source Name Office of Pesticide Programs (OPP) Health Effects Data

Data Source Description EPA’s Office of Pesticide Programs publishes health effects data in a 

variety of sources, including Reregistration Eligibility Decision (RED) 

Documents and Health Assessments. "When EPA completes the review 

and risk management decision for a pesticide that is subject to 

reregistration (i.e., one initially registered before November 1984), EPA 

generally issues a RED document. The RED summarizes the risk 

assessment conclusions and outlines any risk reduction measures 

necessary for the pesticide to continue to be registered in the U.S."

There are REDs for over 176 pesticides currently. Two other types of 

documents – the Interim RED and Tolerance RED may also be issued. 

The IRED is issued when a pesticide is undergoing reregistration, 

requires a reregistration eligibility decision, and also needs a cumulative 

assessment. A TRED may be issued if no changes in the tolerances for a 

pesticide are required as a result of EPA's review. 

EPA has also developed human health benchmarks (HHBPs) for 

approximately 363 pesticides to enable states, tribes, water systems, the 

public and other stakeholders to better determine whether the detection 

of a pesticide in drinking water or source waters for drinking water may 

indicate a potential health risk. The HHBP table includes pesticide active 

ingredients for which Health Advisories or enforceable National Primary 

Drinking Water Regulations (e.g., maximum contaminant levels) have not 

been developed. For pesticides with HHBPs, EPA checked the source 

document used to develop the HHBP to determine if there were any new 

or updated health effects data for CCL 4. These source documents can 

be found by clicking on the pesticide name at the following 

link: http://www.epa.gov/pesticides/hhbp

(Description adapted from website.)

Proprietor EPA Office of Pesticide Programs

Contact Information US Environmental Protection Agency

Office of Pesticide Programs 

Washington, DC 20460

Telephone 703-308-8000

Type of Data Elements Name, Synonyms, Drinking Water Level of Concern (DWLOC), 

Population Adjusted Dose (PAD), Reference Dose (RfD), Safety Factors, 

Lethal Concentration (LCx), Lethal Dose (LDx), Lowest Observed 

Adverse Effect Level LO(A)EL, Margin of Exposure (MOE), No Observed 

Adverse Effect Level (NO(A)EL), highest dose tested (HDT) 

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Relevance Explanation This source is considered relevant for the CCL Universe because it 

contains data elements from toxicological studies

Completeness Explanation It meets considerations because it is peer reviewed.

Redundancy Explanation This source is not redundant.

Retrievability Explanation This source does not meet retrievability criteria because the data are not 

formatted for automated retrieval.

Source URL http://iaspub.epa.gov/apex/pesticides/f?p=chemicalsearch:1

Data Source Name Office of Solid Waste and Emergency Response (OSWER) 

Provisional Peer-Reviewed Toxicity Values for Superfund 

(PPRTV)

Data Source Description The Provisional Peer-Reviewed Toxicity Values (PPRTVs) currently 

represent the second tier of human health toxicity values for the EPA 

Superfund and Resource Conservation and Recovery Act (RCRA) 

hazardous waste programs. A PPRTV is a toxicity value derived for use 

in the Superfund Program when such value is not available in EPA's 

Integrated Risk Information System (IRIS). PPRTVs are derived after a 

review of the relevant scientific literature using the methods, sources of 

data and guidance for value derivation used by the EPA IRIS Program. 

All provisional peer-reviewed toxicity values receive internal review by 

EPA scientists and external peer review by independent scientific 

experts. PPRTVs differ from IRIS values in that PPRTVs do not undergo 

a multi-program internal agency review, inter-agency review, or public 

comment. Additionally, IRIS values are generally intended to be used in 

all EPA programs, while PPRTVs are developed specifically for the 

Superfund Program.

The development of PPRTVs enables OSWER to make informed cleanup decisions regarding the screening of chemicals of concern, conduct 

human health risk assessments and evaluate alternative clean-up 

actions at federal and state Superfund sites, which can lead to 

improvements in human and ecological health in the vicinity of Superfund 

sites, as well as improved economic conditions and quality of life for 

nearby communities. PPRTVs are also used by EPA’s regions when 

making site specific clean-up decisions.

PPRTVs are prepared on an ongoing basis for those substances found 

at clean-up sites and for which no IRIS value is available. The purpose of 

PPRTV documents are to provide hazard and dose-response 

assessments pertaining to chronic and subchronic exposures to 

substances of concern, present the major conclusions reached in the 

hazard identification and derivation of the PPRTVs and characterize the 

overall confidence in these conclusions and toxicity values. PPRTV 

assessments are updated approximately on a 5-year cycle for new data 

or methodologies that might impact the toxicity values or characterization 

of potential for adverse human health effects and are revised as 

appropriate. (Description adapted from website.)

Proprietor U.S. EPA Office of Solid Waste and Emergency Response (OSWER) / 

Office of Superfund Remediation and Technology Innovation (OSRTI) & 

U.S. EPA Office of Research and Development (ORD)/ National Center 

for Environmental Assessment (NCEA)

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Contact Information Annette Gatchett

ORD/ NCEA

Gatchett.Annette@epa.gov

Michele Burgess 

OSWER/ OSRTI

Burgess.Michele@epa.gov

Type of Data Elements Name, Synonyms, CASRN, RfC, RfD, LOAEL, Critical effect, Cancer 

classification

Relevance Explanation This source is considered relevant for the CCL Universe because it 

contains data elements from toxicological studies.

Completeness Explanation This source meets all completeness considerations because it is peer 

reviewed.

Redundancy Explanation This source is not redundant.

Retrievability Explanation Data are retrievable by EPA but require special processing and analysis 

for CCL use. 

Source URL http://hhpprtv.ornl.gov/index.html

Data Source Name Pesticide Data Program

Data Source Description The USDA Pesticide Data Program (PDP) has developed a national 

pesticide residue database. PDP was initiated in 1991 to collect data on 

pesticide residues in food with sampling conducted on a statistically 

defensible representation of pesticide residuals in the United States food 

supply. Sampling and testing are conducted on fruits and vegetables, 

select grains, milk and (as of 2001) drinking water. The PDP drinking 

water sampling program was initiated at community water systems 

(CWSs) in New York and California in 2001. Since then, the drinking 

water sampling program has expanded, though the States where 

sampling occurs may differ from year to year. At one time or another, 

CWSs in 27 states and Washington, D.C. contributed raw and/or finished 

water data to the program. The sampling frame is designed to provide 

coverage in regions of interest for at least two years, to reflect the 

seasonal and climatic variability during growing seasons. PDP works 

with EPA and the American Water Works Association (AWWA) to identify 

specific water treatment facilities to be monitored. EPA reviews the PDP 

data on the occurrence of select contaminants in untreated and treated 

water. The CWSs selected for sampling tend to be small- and mediumsized systems (primarily CWSs serving less than 50,000 persons), 

systems served by surface water, and systems located in regions of 

heavy agriculture. The number of sites and samples has varied during 

different sampling periods. Sampling of untreated water in addition to 

treated water began in 2004. EPA had previously compiled the 2001 and 

2002 PDP data for CCL 3. EPA compiled the 2003 through 2009 PDP 

data used in CCL 4 in December, 2011. (Description adapted from 

website.)

Proprietor USDA

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Contact Information PDP Staff: 

Agricultural Marketing Service 

Science & Technology, Monitoring Programs Office

8609 Sudley Road, Suite 206

Manassas, VA 20110 

Director: Martha Lamont 

Phone: (703) 330-2300 ext. 17 

Fax: (703) 369-0678

Deputy Director: Diana Haynes

Phone: (703) 330-2300 ext. 34 

Fax: (703) 369-0678

E-mail: amsmpo.data@ams.usda.gov

Type of Data Elements Total Samples Analyzed, Samples with Residues Detected, Percent of 

Samples with Detections, Pesticides Detected, Residues Detected, Total 

Residue Detections, % of Samples with Detects, Minimum Value 

Detected (ppm), Maximum Value Detected (ppm), Number of Detections 

of Pesticides in Drinking Water, Pesticides Detected Above Limit of 

Quantification in Drinking Water

Relevance Explanation This source is considered relevant for the CCL Universe because it 

contains measurements of pesticide residues in water, demonstrating 

occurrence.

Completeness Explanation It meets considerations because it meets all NDWAC minimum data 

requirements (i.e., contact information for an administrator of the data 

source, a list of data elements in the data source, and an explanation of 

how the data were generated).

Redundancy Explanation This source is not redundant.

Retrievability Explanation This source meets retrievability criteria because it is in tabular format.

Source URL http://www.ams.usda.gov/science/pdp/index.htm

Data Source Name State Drinking Water Data Sets

Data Source Description For EPA’s Second Six-Year Review of drinking water regulations, EPA 

requested (through an ICR) that primacy agencies submit drinking water 

compliance occurrence data to EPA that was collected during 1998-

2005. Eight states (CA, FL, IL, NC, OH, SD, TX, and WI) and the Region 

9 tribes also submitted PWS occurrence data for unregulated 

contaminants in addition to the data for regulated contaminants. EPA 

was able to supplement these data on unregulated contaminants by 

downloading additional publicly available monitoring data from State 

Web sites (specifically, from Florida and Wisconsin). The result was a 

collection of unregulated contaminant monitoring data from nine states 

(eight states and one tribal entity; this support document uses the term 

“state” for SDWA primacy entities for convenience) The nine data sets 

vary in the range of monitoring dates (in some cases extending beyond 

the 1998-2005 period of interest for Six-Year Review), the number of 

contaminants monitored, the number of systems reporting monitoring, 

and the number of samples taken. The data sets vary widely in the 

number of PWSs sampled in each State relative to the total number of 

PWSs in that State. Hence, these data are used only to augment and 

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complement any national drinking water data and to assess any unique 

occurrence that may suggest a need for further review.

Proprietor EPA OGWDW; The Cadmus Group, Inc.

Contact Information Erin Mateo

The Cadmus Group

100 5th Ave Suite 100

Waltham, MA 02451

Phone: 617-673-7000

Type of Data Elements Drinking water occurrence concentrations, number of PWSs with 

samples, etc.

Relevance Explanation This source is considered relevant for the CCL Universe because it 

contains measurements of contaminants in water, demonstrating 

occurrence. Most data are available for regulated contaminants. Some 

data are available for unregulated contaminants.

Completeness Explanation It meets considerations because it meets all NDWAC minimum data 

requirements.

Redundancy Explanation This source is partially redundant, since data for contaminants that are 

regulated in drinking water are available as part of the National 

Contaminant Occurrence Database (NCOD) - Six Year. 

Retrievability Explanation Data are retrievable by EPA but require special processing and analysis 

for CCL use. 

Source URL Internet source not available 

Data Source Name STORET - STORage and RETrieval

Data Source Description STORET is a water quality, biological, and physical property data 

warehouse, containing information collected from over 60 organizations 

including States, tribes, watershed groups, other Federal Agencies, 

volunteer groups and universities. The extent of national coverage and 

data completeness varies from parameter to parameter. Many (though 

not all) sample results are accompanied by information on sample 

location (e.g., latitude, longitude, state, county, Hydrologic Unit Code and 

a brief site identification), sample date, the medium sampled (e.g., water, 

sediment, fish tissue) and the name of the organization that sponsored 

the monitoring. In addition, there can be information on why the data 

were gathered; sampling and analytical methods used; the laboratory 

used to analyze the samples; the quality control checks used when 

sampling, handling the samples, and analyzing the data; and the 

personnel responsible for the data. All data supplied to EPA since 

January 1, 1999 have been placed in the STORET Data Warehouse. 

Data supplied to EPA before 1999 are stored in the Legacy STORET 

Data Center. EPA downloaded STORET data for use in CCL 4 in 

January, 2013. (Description adapted from website.)

Proprietor EPA

Contact Information STORET User Assistance: 1-800-424-9067 or STORET@epa.gov

Type of Data Elements Water occurrence data elements, measured concentrations, number of 

sites, number of detections, etc.

Relevance Explanation This source is considered relevant for the CCL Universe because it 

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contains measurements of contaminants in water, demonstrating 

occurrence.

Redundancy Explanation This source is not redundant.

Retrievability Explanation Data are retrievable by EPA but require special processing and analysis 

for CCL use. 

Source URL http://www.epa.gov/storet/

Data Source Name Toccalino, et al., 2010. Quality of Source Water from PublicSupply Wells in the United States, 1993–2007 - USGS

Data Source Description As part of USGS’s National Water Quality Assessment (NAWQA) 

program, water samples were collected from source (untreated) ground 

water from 932 public water system wells located in parts of 40 NAWQA 

Study Units in 41 states. Each well was sampled once between 1993 

and 2007. Water samples were analyzed for up to 215 regulated and 

unregulated contaminants and several water-quality properties (e.g., 

hardness). The public wells sampled in this study represented 629 

unique PWSs, representing 0.5% of the approximately 140,000 ground 

water-supplied PWSs, but nearly 25% of the population served by 

ground water supplied PWSs in the United States. 

Reference: Toccalino, P.L., Norman, J.E., and Hitt, K.J., 2010, Quality of 

source water from public-supply wells in the United States, 1993–2007: 

U.S. Geological Survey Scientific Investigations Report 2010-5024, 206 

p.

Proprietor United States Geological Survey (USGS)

Contact Information Chief, National Water-Quality Assessment Program

U.S. Geological Survey

413 National Center

12201 Sunrise Valley Drive 

Reston, Virginia 20192

http://water.usgs.gov/nawqa/studies/public_wells/

Type of Data Elements Measured contaminant concentrations from water samples, number of 

samples/sites/PWSs with samples, number of detections, etc.

Relevance Explanation This source is considered relevant for the CCL Universe because it 

contains data elements for contaminant occurrence in source water 

obtained from public-supply wells.

Completeness Explanation It meets all considerations because it is peer reviewed.

Redundancy Explanation This source is not redundant though some, but not all, data may overlap 

with Hopple et al. and with the NAWQA database analyzed separately 

for CCL 3. 

Retrievability Explanation This source contains tabulated occurrence data that can be copied and 

formatted.

Source URL http://pubs.usgs.gov/sir/2010/5024/

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Data Source Name The Toxics Release Inventory (TRI)

Data Source Description TRI contains information from almost 20,000 U.S. companies and 

government facilities that report their air, land and water releases of 

industrial chemicals and other waste management activities. TRI also 

contains some information about source reduction efforts. This 

database’s information on releases to water is a valuable source of 

potential occurrence data for screening drinking water contaminants for 

the CCL. It includes many categories of air, land, and water release data 

for the years 1988 through 2010. As of 2010, the TRI toxic chemical list 

contains 498 individually listed chemicals. EPA downloaded the 2010 

TRI data (used in CCL 4) in March 2012. Facilities may also revise or 

withdraw submittals that they have made under TRI. This may explain 

why data for a given chemical and year (i.e., pounds released and 

number of states where a chemical was released) were sometimes 

observed during the compilation of CCL 3 to change over time after initial 

release of the data to the public (Description adapted from website.)

Proprietor EPA

Contact Information (800) 424-9346 - select option 3

(703) 412-9810 - Wash. DC metro area

(800) 553-7672 – TDD

Email: tri.us@epa.gov

Type of Data Elements Pounds per year of chemical releases to air, land and water

Relevance Explanation This source is considered relevant for the CCL Universe because it 

contains information on chemical releases, which may indicate potential 

occurrence.

Completeness Explanation It meets considerations because it is peer reviewed.

Redundancy Explanation This source is not redundant.

Retrievability Explanation This source meets retrievability criteria because it is in tabular format.

Source URL http://www.epa.gov/triexplorer/

Data Sources for Microbial Contaminants

Data Source Name Center for Disease Control and Prevention’s Morbidity and 

Mortality Weekly Reports (MMWR)

Data Source Description Since 1971, CDC, EPA and the Council of State and Territorial 

Epidemiologists (CSTE) have maintained a collaborative surveillance 

system for collecting and periodically reporting data related to 

occurrences and causes of Water Borne Disease Outbreaks (WBDOs). 

These reports from the CDC are published periodically in the MMWR. 

For CCL 3 EPA used CDC’s MMWR summaries as the source for the 

WBDO scoring protocol. The summaries include data on outbreaks 

associated with drinking water, recreational water, water not intended for 

drinking (excluding recreational water) and water use of unknown intent. 

Public health agencies are responsible for investigating outbreaks and 

reporting them voluntarily to CDC using a standard form. Only data on 

outbreaks associated with drinking water, water not intended for drinking 

(excluding recreational water) and water use of unknown intent are 

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summarized in this report. CDC and EPA acknowledge that the WBDOs 

reported in the surveillance system represent only a portion of the 

burden of illness associated with drinking water exposure. The 

surveillance information does not include endemic waterborne disease 

risks. (Description adapted from website.)

Proprietor CDC

Contact Information Division of Foodborne, Waterborne, and Environmental Diseases, 

National Center for Emerging and Zoonotic Infectious Diseases, 

CDC, 1600 Clifton Road, N.E., MS C-9, 

Atlanta, GA 30333. 

Telephone: 404-639-1700; 

E-mail: healthywater@cdc.gov

Type of Data Elements Waterborne outbreak data

Relevance Explanation This source is considered relevant for the CCL process because it 

contains information on drinking water outbreaks caused by microbial 

contaminants which is a major component of the scoring process.

Completeness Explanation It meets considerations because it is peer reviewed.

Redundancy Explanation This source is not redundant.

Retrievability Explanation This source meets retrievability criteria because it is in tabular format.

Source URL http://www.cdc.gov/mmwr/indss_2011.html

Data Source Name EPA Literature Search for Supplemental Data for Microbial 

Contaminants

Data Source Description As part of its ongoing assessment of microbes in drinking water, EPA 

conducted a literature review of peer-reviewed, published journal 

literature for health effects and occurrence data for nominated microbes 

from 2007 through 2012. EPA reviewed all relevant research reports 

found to identify papers that might present data for the nominated

microbes that might help inform CCL 4. EPA also reviewed studies 

submitted and referenced by nominators.

Proprietor U.S. EPA

Contact Information Cesar Cordero

Email: cordero.cesar@epa.gov

Type of Data Elements Health effects, drinking water occurrence data elements

Relevance Explanation This source is considered relevant for the CCL process because it 

contains information on health effects and occurrence in water.

Completeness Explanation It meets considerations because the studies were peer-reviewed. 

Redundancy Explanation This source is not redundant (though some, but not all, data may overlap 

among papers by the same authors).

Retrievability Explanation Data not retrievable. This source contains written and tabulated data that 

can be copied and formatted. 

Source URL Not applicable

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Data Source Name Manual of Clinical Microbiology (MCM), 10th Edition

Data Source Description The 10th edition of the MCM is the result of collaborative efforts of 22 

editors and more than 267 authors from around the world, all 

experienced researchers and practitioners in medical and diagnostic 

microbiology. The manual has been brought fully up to date, resulting in 

149 chapters containing the latest research findings, infectious agents, 

methods, practices and safety guidelines. Now entering its fifth decade 

the Manual strives to continue to be the leading, most authoritative 

reference for the “real-world” practice of clinical microbiology. This 

publication builds on the content of past editions. The process requires 

about 3 years of careful planning, design, writing and review of chapters 

before the final phases of copyediting, composition, printing and binding. 

(Description adapted from website.)

Proprietor ASM Press, Washington, DC

Contact Information James Versalovic

Microbiology Laboratories

Texas Children’s Hospital

Houston, Texas

Type of Data Elements Production Volume

Relevance Explanation This source is considered relevant for the CCL Universe because it 

contains health effects and occurrence information on microbial 

pathogens.

Completeness Explanation It meets considerations because it is peer reviewed.

Redundancy Explanation This source is not redundant.

Retrievability Explanation This source is not automatically retrievable. It is a book available for 

purchase.

Source URL http://mcm10.asmpress.org/

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