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Summary of Comments and Discussion

U.S. Environmental Protection Agency

Preliminary Regulatory Determinations for the Third Contaminant Candidate List

STAKEHOLDER MEETING

Washington Plaza Hotel

10 Thomas Circle NW

Washington, DC 20005

June 16, 2011

Welcome and Opening Remarks 

Pamela Barr, U.S. EPA

 Every five years, EPA is required to make decisions on at least five contaminants on the 

Contaminant Candidate List (CCL). The next set of determinations is due in final form in 

the summer of 2013. EPA has made no decisions at this point, and some information is 

still being collected and updated.

 EPA welcomes comments from stakeholders during this process.

George Hallberg, Cadmus (Facilitator)

 The meeting objectives are as follows:

o Provide an overview of the Safe Drinking Water Act (SDWA) regulatory

processes with a specific focus on the regulatory determinations for unregulated 

contaminants listed on the Contaminant Candidate List.

o Discuss the approach and data sources being used to evaluate potential 

contaminants for Regulatory Determinations 3.

o Share and discuss health effects and occurrence information for specific 

contaminants being evaluated for Regulatory Determinations 3.

o Solicit input/feedback from stakeholders on contaminants and information under 

consideration.

 After each presentation, stakeholders are invited to ask questions or provide comments. 

EPA is particularly interested in information regarding additional sources of data. 
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Overview of the Various SDWA Regulatory Processes, the Contaminant (CCL) and 

Regulatory Determinations Process

Wynne Miller, U.S. EPA

 This presentation covered the following topics:

o An overview of SDWA regulatory processes.

o An overview of SDWA statutory criteria for Regulatory Determinations and 

potential outcomes.

o The history and timeline for previous CCL and Regulatory Determination efforts. 

Overview of Approach to Evaluate Potential Contaminants for Regulatory Determinations

Zeno Bain, U.S. EPA

 This presentation covered the following topics:

o The approach used to screen and identify potential contaminants for Regulatory

Determinations.

o The approach and information considered in evaluating contaminants against the 

three SDWA statutory criteria for proceeding with a drinking water regulation.

o A list of potential contaminants being evaluated for Regulatory Determinations 3.

o An introduction to the Drinking Water Strategy.

 A participant made recommendations related to stakeholder access and involvement. This 

meeting was advertised in a Federal Register (FR) notice two weeks in advance and 

potential participants were given five business days to pre-register. The participant 

recommended that EPA allow for written comments to be submitted after the meeting, 

when participants and others have had an opportunity to review the materials in more 

detail. The participant also suggested that EPA provide notice of stakeholder 

opportunities farther in advance and perhaps hold more frequent meetings to increase 

stakeholder access. EPA explained that this meeting was planned so it would be 

convenient for attendees of the American Water Works Association’s 130th Annual 

Conference & Exposition (ACE), which was held in Washington, D.C. on June 11 to 16, 

2011. EPA will try to allow more time for registration in the future. In addition, EPA

noted that potential meeting participants should not hesitate to contact EPA even after a 

registration deadline has passed. The deadline was established to get a tentative 

headcount, so an appropriate meeting facility could be reserved. EPA would encourage 

all to attend the meetings as long as space allows.

 A participant asked if EPA will make meeting materials available in PDF format. EPA 

does plan to make the presentations available on the Agency website.
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Contaminants Being Evaluated for Regulatory Determinations 3 (Part 1)

Zeno Bain, U.S. EPA

 This presentation provided background, health effects, and occurrence information for the 

following contaminants:

o Nitrosamines (considered as a group):

 N-nitrosodimethylamine (NDMA). 

 N-nitrosodiethylamine (NDEA).

 N-nitrosodi-n-propylamine (NDPA). 

 N-nitrosopyrrolidine (NPYR). 

 N-nitrosodiphenylamine (NDPhA).

o Chlorate.

 A participant asked if EPA plans to revisit the cancer slope factors for all carcinogens 

based on the 2005 guidelines. EPA will follow the 2005 guidelines for all mutagenic 

carcinogens and revise the cancer slope factors accordingly. EPA explained that fetuses, 

infants and children are especially sensitive to the nitrosamine compounds, so it is 

important to apply the Age Dependent Adjustment Factor (ADAF). In addition, early

exposure may lead to increased risk of cancer later in life, and additive risk should also 

be taken into consideration.

 EPA clarified that the infant formula powder data (presented on slide 29) only represents 

the concentration in dry powder. Because NDMA levels in formula have decreased to 

below detection limits, the primary source of exposure to infants drinking formula would 

be the water used to reconstitute the formula.

 A participant asked about the advantages of regulating contaminants as a group. EPA 

explained that it may be more efficient to regulate contaminants as a group; EPA can 

develop one regulation instead of several individual regulations. Regulating contaminants 

as a group may also be more efficient for public water systems, because they can plan 

treatment strategies based on the group of contaminants rather than adjusting their 

practices several times in response to several individual regulations. Also, the group 

approach may address additive risk, as well as potentially providing public health 

protection from other related contaminants.

 A participant asked how EPA plans to address situations where the Minimum Reporting 

Level (MRL) is greater than the Health Reference Level (HRL). EPA noted that there is 

ongoing research in this area; however, at this time EPA must work with the approved 

analytical methods. If EPA did decide to regulate nitrosamines, for example, the Agency

would need to consider constraints on analytical feasibility posed by the MRL when 

establishing the Maximum Contaminant Level (MCL). There are a number of regulated 

compounds where the MCL has been limited by analytical feasibility. EPA would also 

need to perform extrapolations to estimate the occurrence of the contaminants at the 

lower value.

 A participant asked if EPA is anticipating a move to advanced treatment methods that 

forgo chloramines in order to reduce nitrosamine formation. EPA responded that this 

issue must be investigated in more detail. However, EPA’s data set does include some 
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systems using chlorine with higher nitrosamine occurrence levels. EPA added that one 

option might be to control organic matter prior to chloramination.

 A participant asked for more information on the Maximum Contaminant Level Goal 

(MCLG) for carcinogens. EPA explained that, prior to the 2005 regulations, all 

carcinogens received a MCLG of zero. However, future Regulatory Determinations may

look at this more closely. If there is a demonstrated mode of action with a quantitative 

precursor effect, then the reference dose, not cancer, would be the controlling effect. EPA 

mentioned chloroform as one example of this situation.

 A participant suggested that, if regulations constrain chloramine use, cost may be a less 

important factor than operational difficulties. Depending on the MCL chosen, operational 

difficulties could preclude the use of chloramines entirely. Constraining the use of 

chloramines could lead to increased issues with other DBPs and impact how water 

systems treat for disinfection. EPA acknowledged that this is an ongoing area of 

discussion and study. 

 A participant described a model that is under development for perchlorate and chlorate. 

Under the worst-case scenario for perchlorate, months of storage time could occur before 

levels of concern are exceeded. However, for chlorate, the model indicates that as little as 

two or three days of storage time could lead to levels higher than the WHO benchmark. 

The participant added that EPA may have to choose which contaminants and issues will 

drive decision making because there may be some risk tradeoffs.

 A participant asked about the sources of occurrence data for contaminants on the CCL, 

and particularly why the CWSS was noted as an occurrence data source. EPA clarified 

that Community Water System Survey (CWSS) data include some occurrence data from 

large systems, as well as data on treatment methods and general trends. The participant 

recommended that EPA provide more specific information on data sources. Other 

participants noted that EPA prepares detailed support documents for the Regulatory

Determination process that provide this type of information. EPA agreed that data 

sources will be described in detail in the support documents.

 EPA clarified that all seven nitrosamines discussed in the presentations, including the two 

included in the second cycle of the Unregulated Contaminant Monitoring Rule (UCMR2)

but not in the CCL3, could be included in the group.

Contaminants Being Evaluated for Regulatory Determinations 3 (Part 2)

Melissa Simic, U.S. EPA

 This presentation provided background, health effects, and occurrence information for the 

following contaminants:

o Molybdenum.

o Strontium. 

o Vanadium.

 A participant asked about the essential nutrient levels for molybdenum. For adults, 

including pregnant women, the amount is 45-50 micrograms per day (per the Institute of 

Medicine, 2001). Essential nutrient levels for infants are based on amounts in maternal 

milk and can also be found in the Institute of Medicine document. EPA added that this is 
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still under investigation as new data become available; if EPA were to develop a new 

reference dose and HRL, they would likely be higher than they are currently.

 A participant asked about the relative contributions of natural and industrial sources for 

IOCs in areas with levels near the HRL. EPA has looked at this issue, and it can’t be 

easily resolved in a broad sense (though in local areas it can sometimes be sorted out). 

However, for naturally-occurring elements like strontium, there is a natural contribution 

to almost all water samples. EPA added that, under SDWA, the source of the contaminant 

does not matter. Instead, EPA only considers whether a contaminant occurs in drinking 

water at frequencies and levels of concern.

 A participant asked if EPA will develop its own risk assessment for vanadium. EPA 

responded that the Integrated Risk Information System (IRIS) currently does not have a 

risk assessment for soluble vanadium salts. However, additional data are becoming 

available from new human-based studies. EPA has also updated its literature search and 

has compiled a new database that is more comprehensive than the Agency for Toxic 

Substances and Disease Registry (ATSDR) toxicological profile. Vanadium may receive 

a revised Office of Water risk assessment value, based on the new data.

 A participant asked about the process of updating risk assessments. EPA reminded all of 

the participants that no decisions or determinations have been made at this time. In 

addition, any new risk assessments prepared for these contaminants is subject to peer 

review. Some occurrence data (such as final data from UCMR2), are not yet available. 

EPA has performed a new literature search for the contaminants with outdated risk 

assessments. EPA has identified new studies and is working on updating risk 

assessments, but (per the process discussed in the introductory presentation) this is an 

ongoing effort. 

Contaminants Being Evaluated for Regulatory Determinations 3 (Part 3)

Zeno Bain, U.S. EPA

 This presentation provided background, health effects, and occurrence information for the 

following contaminants:

o 1,1,1,2-Tetrachloroethane.

o 1,2,3-Trichloropropane.

o 1,3-Dinitrobenzene.

o 1,4-Dioxane.

o Methyl Tertiary Butyl Ether (MTBE).

o Nitrobenzene.

o PFOS and PFOA.

o RDX.

 A participant noted the importance of considering PFOS and PFOA separately, based on 

their individual chemical properties. The participant noted that industry has been 

partnering with EPA on a stewardship program that aims to phase out PFOA emissions 

and product content over the next several years. The participant also suggested that 

occurrence data for PFOA is not robust or representative enough for a Regulatory

Determination at this time. 
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 EPA clarified that when there are no detects above the HRL, detects above half the HRL 

are presented in the slides. If there are no detects above half the HRL, EPA presents the 

total number of detects.

 A participant noted that three chemicals discussed in this presentation had zero, two, or 

three detects in the UCMR1 and UCMR2 data, and that this would seem to indicate a 

negative Regulatory Determination. The participant added that obtaining additional 

representative data is not an issue when UCMR results are available. 

Contaminants Being Evaluated for Regulatory Determinations 3 (Part 4)

Guy Cole, U.S. EPA

 This presentation provided background, health effects, and occurrence information for the 

following contaminants:

o Dimethoate.

o Disulfoton.

o Diuron.

o Molinate.

o Terbufos and Terbufos Sulfone.

 A participant asked about the PBT Profiler. EPA explained that the model places halflives (and other predicted properties) into bins or categories, which results in some 

repetition of reported half-life values.

Contaminants Being Evaluated for Regulatory Determinations 3 (Part 5)

Ali Arvanaghi, U.S. EPA

 This presentation provided background, health effects, and occurrence information for the 

following contaminants:

o Acetochlor and its ESA and OA degradates.

o Alachlor ESA and OA degradates (alachor is currently regulated).

o Metolachlor and its ESA and OA degradates.

 EPA provided some additional information about the Pesticide Data Program (PDP). PDP 

is a U.S. Department of Agriculture (USDA) program that is best known for monitoring 

pesticide residue on foods. However, it also includes some finished water data.

 A participant asked if the studies of contaminant degradates considered the occurrence of 

the parent compound. EPA noted that while data on parent compounds were available in 

some reports, the published reports did not always present information on their cooccurrence. EPA did not have the “raw” data from these studies and could only note what 

was stated in the reports. Some older U.S. Geological Survey (USGS) papers have 

observed that degradates are more widely detected than the parent compounds, because 

the parent has degraded.

 A participant expressed support for a positive Regulatory Determination on this set of 

contaminants. Some states have listed waters as “impaired” because they contain these 

contaminants. The participant added that industry has been working with EPA to collect 
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data and derive reference doses. Another participant noted that there have been limited 

detections for these contaminants, suggesting that they should not be regulated.

 A participant asked whether EPA might consider pesticides as a group or as subgroups. 

EPA recapped the four grouping criteria with regard to their applicability to pesticides. 

First, there are no common analytical methods for the broader groups of “pesticides,”

though there are potential opportunities for research in this area. Second, only the more 

advanced or expensive treatment options are common to the group. Third, occurrence 

data are limited, especially regarding co-occurrence. Finally, only small subgroups have 

common health endpoints. EPA has not ruled out considering these or other contaminants 

as groups, but it appears unlikely that EPA will be able to formulate a broad pesticide 

group. 

Additional Questions

 A participant asked why the hormones included in the CCL3 were not selected for further 

consideration. EPA responded that occurrence data were too limited. However, several 

hormones are proposed for UCMR3, which should provide more comprehensive data.

 A participant asked under what conditions EPA considers early life stages to be sensitive 

subpopulations. EPA explained that, as more studies are conducted and more data 

become available, early life stages will likely be considered sensitive subpopulations for 

more contaminants. For example, recent strontium studies have indicated that neonates 

and adults respond differently across a range of doses. EPA will also be considering early 

life stages when it applies the Age Dependant Adjustment Factor. In addition, the 1996 

SDWA amendments require EPA to consider sensitive sub-populations when developing 

or revising regulations. Because of this, EPA takes sensitive sub-populations into account 

during the Six-Year Review process as well.

 A participant asked if EPA is considering a different review schedule for the nitrosamines 

and other grouped contaminants. EPA responded that no decisions have been made at this 

time, but the nitrosamines will be considered as a possible group during the Regulatory

Determination process. At this point, only the carcinogenic volatile organic contaminants 

(VOCs) have been slated for review for regulation as a group.

Next Steps and Closing Remarks

Pamela Barr, U.S. EPA

 EPA asked participants to submit additional information by e-mail to Zeno Bain at 

bain.zeno@epa.gov. 

 EPA will develop draft determinations by the summer of 2012 in order to meet the final 

deadline of summer 2013. EPA does not anticipate that it will be able to hold any more 

public meetings, but there will be a public comment period for the draft determinations 

and EPA will consider these comments as it develops the final determinations.