1

Six-Year Review 2 -- Summary of Public Comments

The Safe Drinking Water Act requires EPA to conduct a periodic review of existing National Primary Drinking Water Regulations (NPDWRs) and determine 

which, if any, need to be revised. The purpose of the review, called the Six-Year Review, is to identify those NPDWRs for which current health effects 

assessments, changes in technology, and/or other factors provide a health or technical basis to support a regulatory revision that will improve or strengthen 

public health protection. On March 29, 2010, EPA announced its completion of its second detailed review of 71 NPDWRs, and nominated 4 NPDWRs as

candidates for regulatory revision: acrylamide, epichlorohydrin, tetrachloroethylene, and trichloroethylene (USEPA, 2010; 75 FR 15500)1. 

Within the Federal Register (FR) notice, EPA requested public comment and/or relevant information that would assist the Agency as it moves forward with 

regulatory action to revise these 4 NPDWRs. EPA included 2 tables listing specific requests for comment: 

Table VII-1 -- Items for Which EPA Is Requesting Comment and/or Information for the Four Candidates for Revision; and

Table VII-2 -- Issues for Which EPA Is Requesting Public Input and/or Information.

EPA received 20 public submissions (in the form of letters, e-mails, and/or postings to www.regulations.gov) which addressed the topics listed in these 

tables, as well as other related topics. Below are 3 tables summarizing public comments received; 2 of these correspond directly to the 2 tables listed above, 

and a 3rd table summarizes comments received on other issues (i.e., other comments received that did not relate to the topics listed in the FR notice tables). 

In addition, the 3 tables below include a column titled “Disposition of Comment Issues,” which contains summaries of the status of EPA’s handling of the 

comments. All original public submissions can be found at www.regulations.gov, under Docket ID EPA–HQ–OW–2008–0747.

Table 1: Comment Summary Corresponding to “Table VII-1 -- Items for Which EPA Is Requesting Comment and/or 

Information for the Four Candidates for Revision” (75 FR 15500, p. 15568)2

Issue

Number of 

Commenters 

and Affiliation

General Summary of Comments Disposition of Comment Issues

Any new, relevant peerreviewed data or information 

that would inform the revision 

of the NPDWR for acrylamide

and epichlorohydrin, including 

information pertaining to 

3 industry 

groups

Commenters believe that EPA should better 

understand dosing ranges used in the United States, 

fully assess treatment implications, and allow for 

short-term variances for unusual situations. 

Some commenters were unclear if NSF data regarding 

lower levels of monomer concentrations were due to 

EPA will consider these comments when

the Agency revises the standards for 

epichlorhydrin and acrylamide.

 

1

USEPA. 2010. National Primary Drinking Water Regulations; Announcement of the Results of EPA’s Review of Existing Drinking Water Standards and Request for Public 

Comment and/or Information on Related Issues; Notice. Federal Register. Vol. 75, No. 59, p. 15500, March 29, 2010.

2

Note that commenters may have submitted more than one comment per issue. Each commenter is counted only once, regardless of the number of comments submitted.
2

Issue

Number of 

Commenters 

and Affiliation

General Summary of Comments Disposition of Comment Issues

extent of use of 

polyacrylamide and 

epichlorohydrin-based 

polymers/co-polymers in 

drinking water facilities.

3

more refined manufacturing techniques or the fact 

that some polymer products contain lower levels of 

active polymers. 

Commenters asked that revisions include clarification 

of the reporting requirements that exist in the current 

rule to alleviate confusion many are experiencing 

now. 

Many commenters support lowering levels of 

acrylamide and epichlorohydrin as long as effective 

treatment can be maintained.

Any new, relevant peerreviewed data or information 

that would inform the revision 

of the NPDWR for 

tetrachloroethylene (PCE) and 

trichloroethylene (TCE), 

including information/data 

about the lowest level of 

quantitation (and analytical 

method used) that laboratories 

can reliable and consistently 

achieve.

4

11

commenters: 3 

States; 3 special 

interest groups; 

4 industry 

groups; and 1 

water system

Commenters question whether the PQL can be 

demonstrably achieved by public water systems 

(PWSs).

Additional research should be conducted to ensure 

that laboratories can meet lower detection levels and 

that laboratory capacity will not be impacted. 

Some laboratories would have trouble at lower 

detection levels with EPA Method 524.2 because the 

signal to noise ratio becomes unmanageable. 

A State reviewed health effects data and PQLs for 19 

contaminants. This State review closely agrees with 

EPA’s findings for TCE and PCE. 

Some commenters recommended that EPA review 

source water occurrence data, co-occurrence with 

other volatile organic compounds (VOCs), the 

laboratory quantitation level, and conduct a multilaboratory analysis on the Lowest Concentration 

Minimum Reporting Level (LCMRL). 

Some commenters thought the final rule revisions 

EPA will consider these comments as it 

develops a proposed regulation for a 

group of carcinogenic volatile organic 

compounds (cVOCs) which will include 

PCE and TCE. EPA plans to propose the 

group regulation in 2013.

 

3

Comments submitted on acrylamide and epichlorohydrin applied to both contaminants, so the issues are combined in this comment summary. 

4

Comments submitted on tetrachloroethylene and tetrachloroethylene applied to both contaminants, so the issues are combined in this comment summary.
3

Issue

Number of 

Commenters 

and Affiliation

General Summary of Comments Disposition of Comment Issues

should be made after the revised risk assessments 

have been completed (Some commenters suggest 

that the draft assessments do not support lowering 

maximum contaminant levels (MCLs), citing a National 

Academies of Science (NAS) review of the PCE draft 

assessment.). 

Many commenters believe the costs—including 

Superfund site cleanup costs—outweigh the benefits 

of lowering the MCLs. Many cite a Tetra Tech Cost 

analysis.

Some commenters noted that the health risk 

reduction benefits need to be quantified. 

Some commenters believe EPA should assess 

treatment technologies to determine if treatment, 

rather than analytical feasibility will be the 

determining factor on setting new MCLs. 

Revising TCE and PCE MCLs provides the opportunity 

to examine regulating contaminants as a group and to 

evaluate risk reduction associated with co-occurring 

contaminants. 

Some commenters believe that EPA should evaluate 

source water specific data (rather than system-level), 

since many systems blend water sources to meet 

current MCLs. 

A commenter noted that lower MCLs will result in 

significant impacts to water systems (including 

additional treatment and simultaneous compliance 

issues) and States that assist water systems with 

compliance. 

Additional or new treatment could impact the air 

quality emissions permits.

Some commenters support EPA’s decision to revise 

EPA conducted occurrence and exposure 

analyses at threshold concentrations that 

are below current maximum contaminant 

levels (MCLs) to determine if there is a 

meaningful opportunity to improve the 

level of public health protection by 

reducing MCLs. The document 
4

Issue

Number of 

Commenters 

and Affiliation

General Summary of Comments Disposition of Comment Issues

MCLs for TCE and PCE. 

Some commenters asked for clarification on which 

datasets were used for the PCE and TCE minimum 

reporting level (MRL) analysis. 

Some commenters provided additional references for 

PCE and TCE health effects.

“Development of Estimated Quantitation 

Levels for the Second Six-Year Review of

National Primary Drinking Water 

Regulations”

(http://water.epa.gov/lawsregs/rulesregs/

regulatingcontaminants/sixyearreview/

second_review/index.cfm) describes the 

method EPA used to establish the 

threshold values (including a detailed 

discussion on the MRL analysis) that it

used for the occurrence analyses.
5

Table 2: Comment Summary Corresponding to “Table VII-2 -- Issues for Which EPA Is Requesting Public Input and/or 

Information” (75 FR 15500, p. 15568)5

Issue

Number of 

Commenters 

and Affiliation

General Summary of Comments Disposition of 

Comment Issues

Location for nitrate and nitrite

monitoring

4 commenters: 

3 industry 

groups; and 1

State

Some commenters support continuing existing entry point 

monitoring – allowing systems to modify management strategies 

as system-specific trends warrant. 

States want flexibility to require distribution system monitoring if 

conditions make other monitoring locations more appropriate. 

Some commenters recommended that EPA provide guidance on 

distribution system nitrification. The guidance could describe 

indicators that can identify nitrification in the distribution system, 

as well as measurement and management practices for naturally 

occurring ammonia in source water and distribution systems. 

Monitoring options permitted by 40 CFR §141.23(a)(2) should be 

included in the guidance. One commenter would support 

distribution system monitoring if data supports monitoring from 

this location.

EPA believes current 

regulations allow for 

flexibility in determining 

sampling point locations

for nitrate. Regulations 

codified in 40 CFR 

§141.23(a)(1) and 

§141.23(a)(2) allow 

public water supply 

systems the flexibility to 

monitor at the sampling 

point that best 

represents the source or 

treatment plant.

Monitoring frequency for ground 

water systems with low nitrate

and nitrite concentrations

6 commenters: 

3 industry 

groups; 1 State; 

and 2 water 

systems

Commenters suggested that if the monitoring frequencies were 

to be reduced for ground water systems, the schedule should be 

aligned with the existing standardized monitoring framework, 

while some commenters believe the current monitoring 

frequency should not change. 

Some commenters noted that monitoring schedules are an 

important indicator that utilities and States can use to identify 

unanticipated changes in ground water characteristics due to 

changes in land use management. 

Some commenters would support using some very low trigger 

(detection limit, one half the MCL or some other low percentage 

EPA does not believe

it is appropriate to 

consider revisions to the 

nitrate and nitrite 

standards or monitoring 

protocol at this time 

because

EPA identified nitrate as 

a candidate for a new 

risk assessment. When 

an updated human 

 

5

Note that commenters may have submitted more than one comment per issue. Each commenter is counted only once, regardless of the number of comments submitted.
6

Issue

Number of 

Commenters 

and Affiliation

General Summary of Comments Disposition of 

Comment Issues

of the MCL), so States could allow reduced monitoring without 

reducing public health protection. In States that evaluated the 

potential impact of such a change in monitoring requirements, as 

many as half the water systems could qualify for reduced 

monitoring under revisions states would support. 

Another commenter believes that monitoring should be 

decreased to no less frequently than once every three years if 

very low levels of nitrate and nitrite are detected.

health risk assessment is 

finalized, EPA will

carefully review the 

conclusions and consider 

all relevant information 

to determine if a new 

standard or monitoring 

protocol is needed. EPA 

would also like to note 

that States are offered 

monitoring relief under 

provisions set forth in 

SDWA 1418 Alternative 

Monitoring Guidelines

(AMG), and detailed in 

62 FR 42990. SDWA, 

therefore, provides that 

a state may allow a 

system to implement the 

alternative monitoring 

offered by these 

guidelines, if the state 

has an approved source 

water assessment 

program, and has 

completed a source 

water assessment for 

that system. The AMG

allows biennial 

monitoring waivers for 

nitrate for groundwater 

systems whose nitrate 
7

Issue

Number of 

Commenters 

and Affiliation

General Summary of Comments Disposition of 

Comment Issues

concentrations have not 

exceeded 2 mg/L at any 

time in the past 10 

years. EPA recognizes 

that the AMG requires

states to go through the 

rule adoption and 

primacy revision 

process, and can be 

burdensome; AMG does 

however provide the 

monitoring relief 

requested by states.

Monitoring requirements for noncommunity water systems

(NCWSs)

3 commenters: 

2 industry 

groups; and 1 

State

Some commenters recommended that states have the flexibility 

to establish NCWS monitoring for all contaminants, consistent 

with the relative health risks of each type of water system and the 

population served. 

One commenter noted that non-transient non-community water 

systems should monitor for radionuclides, and states should have 

the flexibility to increase monitoring for transient non-community 

water systems. 

One commenter recommended no change for NCWS monitoring.

EPA has previously taken 

comment on whether 

NCWS should be 

required to monitor for 

the same contaminants 

as community water 

systems (CWS). 

Commenter’s responses 

were not definitive on 

the issue 

(52 FR 25690, p 25694) 

(65 FR 76708, p 76719)

(66 FR 6975, p 7025).

Regarding applicability 

of regulations to noncommunity water 

systems, EPA considers 

the merits of each 

rulemaking on a case-by-
8

Issue

Number of 

Commenters 

and Affiliation

General Summary of Comments Disposition of 

Comment Issues

case basis using a 

consistent set of criteria 

namely the cost/benefit

analysis as required 

under SDWA section 

1412(b)(4). EPA will 

continue to evaluate the 

applicability of new 

regulations to NCWS. 

Further, EPA believes 

States currently have the 

discretion to choose to 

regulate NCWS either 

under a targeted rule or 

otherwise.

Detection limits as triggers to 

determine synthetic organic 

chemical monitoring frequency 

5 commenters: 

1 industry 

group; 1 State; 1 

water system; 

and 2 laboratory 

associations

Laboratories can meet the detection limits for synthetic organic 

chemicals (SOCs). Specifically, benzo(a)pyrene, endrin, and 

methoxychlor detection limits can be met using EPA Method 505. 

One commenter suggested that EPA use MRLs rather than 

method detection limits (MDLs). Meeting MRLs should then be 

used as a requirement for drinking water laboratories to receive 

certification. 

EPA will consider the 

efficacy of using MRLs in 

future rulemaking 

activities.

Health effects data for chromium

health assessment

2 commenters: 

1 industry 

group; and 1 

State

One commenter agrees with concerns that the large doses 

administered in the National Toxicology Program (NTP) led to 

health effects that cannot be extrapolated to low-dose exposures 

in drinking water. The commenter recommends that EPA 

incorporate “The Hamner Institutes for Health Sciences, Research 

Framework for Evaluating the Potential Mode(s) of Action 

Underlying the Carcinogenicity of Hexavalent Chromium 

Following Exposure in Drinking Water” framework into its risk 

assessment for chromium.

One commenter provided a link to the final New Jersey 

EPA began a rigorous 

and comprehensive 

review of chromium-6 

health effects following 

the release of the 

toxicity studies by the 

National Toxicology 

Program in 2008. In 

September 2010, EPA 

released a draft of 
9

Issue

Number of 

Commenters 

and Affiliation

General Summary of Comments Disposition of 

Comment Issues

Department of Environmental Protection (NJDEP) risk 

assessment: http://www.state.nj.us/dep/dsr/chromium/soilcleanup-derivation.pdf. In addition, the State is evaluating the risk 

assessment and deciding whether or not to recommend an MCL 

for hexavalent chromium in drinking water. 

the scientific assessment 

“Toxicological Review of 

Hexavalent Chromium”

for public comment and 

external peer review. 

When this human health

risk assessment is 

finalized, EPA 

will carefully review the 

conclusions and consider 

all relevant information 

to determine if a new 

standard is needed

Health effects data for nitrate and 

nitrite health assessment

4 commenters: 

1 industry 

group; 2 special 

interest groups; 

and 1 State

Commenters believe that EPA should not invest limited resources 

in a further analysis of nitrate because the inhibition of iodine is 

not an adverse affect, it is a precursor effect. EPA should develop 

strategies to increase maternal iodide intake to healthy levels. 

Some commenters believe that the scientific literature does not 

support conclusions reached in the federal register notice, and 

does not warrant a new health assessment for nitrate and nitrite, 

while some commenters believe that a new risk assessment for 

nitrate and nitrite should be completed.

EPA must consider a more comprehensive body of scientific 

literature in examining developmental effects and carcinogenicity 

of nitrate and nitrite. 

EPA is still considering 

the need for a health 

assessment revision for 

nitrate and nitrite along 

with other 

programmatic priorities.

Health effects data for selenium

health assessment

No comments 

received

No comments received. No action. 

Health effects data for 1,2,4-

trichlorobenzene health 

assessment

1 State

One commenter supports EPA conducting a new health effects 

assessment of 1,2,4-trichlorobenzene. The commenter cited 

several studies that would support changing the MCL to 20 μg/L.

EPA’s Office of Ground 

Water and Drinking 

Water identified 1,2,4-

trichlorobenzene as a 

program priority for a 
10

Issue

Number of 

Commenters 

and Affiliation

General Summary of Comments Disposition of 

Comment Issues

revised IRIS risk 

assessment.
11

Table 3: Comment Summary Corresponding to Other Issues Related to the Six-Year Review Federal Register Notice (75 

FR 15500)6

Issue

Number of 

Commenters 

and 

Affiliation

General Summary of Comments Disposition of Comment Issues

General 

comments 

agreeing with 

EPA

3 

commenters: 

2 industry 

groups; and 1 

State

Some commenters support EPA’s efforts to review existing drinking water 

contaminants and the decision to revise standards for some contaminants.

No Action. Thank you for your 

comments.

General 

comments 

disagreeing 

with EPA

2 

commenters: 

1 special 

interest 

group; and 1 

environmental 

group

Commenters believe that EPA has not clearly demonstrated the benefits of 

reducing MCLs for TCE and PCE to justify cost of compliance and impacts to 

Superfund clean-up. 

Commenters also oppose the inclusion of “Category 5” and “Category 9” 

(option to raise MCL) in EPA’s review categorization.

EPA will evaluate the cost and 

benefits of revising the MCLs for 

TCE and PCE as it develops a 

proposed regulation for a group of 

carcinogenic volatile organic 

compounds (cVOC). In evaluating 

costs, Superfund cleanup is not a 

consideration because SDWA 

1412(b)(3)(C)(i)(III) excludes cost 

considerations resulting in 

compliance with other regulations.

The categorization was simply 

intended to organize/present the 

health effects information 

identified during the extensive 

literature review conducted to 

identify peer-reviewed studies that

may potentially affect the MCLGs.

Climate 

change 

impacts

2 industry 

groups

One commenter suggested that EPA conduct long-term studies on the effects 

of climate change on drinking water systems, rather than focusing on 

individual events. 

In 2008, EPA released its “National 

Water Program Strategy: Response 

to Climate Change” which provides 

 

6

Note that commenters may have submitted more than one comment per issue. Each commenter is counted only once, regardless of the number of comments submitted.
12

Issue

Number of 

Commenters 

and 

Affiliation

General Summary of Comments Disposition of Comment Issues

EPA may also want to develop a guidance document to describe potential 

indicators of climate change to be measured. One commenter noted that 

climate change impacts will vary by region. 

an overview of the likely effects of 

climate change on water resources 

and the Nation’s clean water and 

safe drinking water programs. It 

also describes specific actions the 

National Water Program intends to 

take to adapt program 

implementation in light of climate 

change. To view the strategy go to: 

http://water.epa.gov/scitech/climat

echange/upload/20081016_nwpsre

sponse_to_climate_change_revised

.pdf

In addition, the agency released

“The National Water Program 

Strategy: Response to Climate 

Change, 2010-2011 National and 

Regional Highlights of Progress”. 

This report is the third progress 

report of the 2008 strategy, 

highlighting the accomplishments 

of the National Water Program in 

2010 and 2011. 

Other nonMCL issues1 water 

system

EPA is encouraged to address implementation issues in each Six-Year Review. No action. Thank you for your 

comment.

Fluoride

9

commenters: 

6 citizens; 1 

special 

Many commenters believe that the fluoride MCL should be revised, suggest a 

number of toxic endpoints, and that any water fluoridation is unsafe. 

Some commenters pointed out that a prescription is normally needed to 

consume fluoride and public water should not be used as a “drug delivery” 

The Agency released a new risk 

assessment for fluoride on January 

7, 2011. Based on the new 

assessment, EPA began the process 
13

Issue

Number of 

Commenters 

and 

Affiliation

General Summary of Comments Disposition of Comment Issues

interest 

group; 1 

industry 

group; and 1 

environmental 

group

system. 

Commenters felt that EPA has been remiss in not responding to the 2006 

National Research Council report, and that an interim MCL and MCLG should 

be set. 

Commenters submitted numerous references and studies on health effects of 

fluoride. 

One commenter is concerned with the multiple public notification 

requirements which create confusion for PWSs and the public, and suggests 

that EPA develop additional guidance. 

of reviewing the current drinking 

water standards (primary and 

secondary MCLs) for fluoride to 

decide whether revisions are 

appropriate. Comments received 

are being reviewed and considered 

as a part of this review.

Other 

contaminants

4 

commenters: 

1 water 

system; 1 

consultant; 1 

environmental 

group; and 1 

State

One commenter suggested that nitrogen and iodine species of disinfection 

byproducts (DBPs) should be added to the list of regulated DBPs. 

Another commenter believes the MCL and maximum contaminant level goal 

(MCLG) for lindane should be reduced based on new health effects 

information. This change would reduce costs for superfund sites. 

One commenter believes that the health effects of alachlor do not support 

weakening the MCL, and that EPA’s reference dose should be based on health 

effects to vulnerable populations. 

One commenter also asked EPA to require more frequent monitoring for 

atrazine. 

One commenter requests clarification on how EPA defined the threshold for 

sufficient occurrence and exposure in determining whether MCLs should be 

revised, and noted that standards should be revised where PQLs could be 

lowered.

The disinfection byproduct rules 

were not subject to this Six-Year 

Review, but will be evaluated in 

the 3rd Six Year Review.

Although there were data that 

supported a consideration to 

revise the MCLG/MCL for lindane, 

EPA did not believe a revision to 

the NPDWR for lindane is 

appropriate at this time. In 

evaluating costs, Superfund 

cleanup is not a consideration 

because SDWA 1412(b)(3)(C)(i)(III)

excludes cost considerations 

resulting in compliance with other 

regulations.

Although there were new data that 

support consideration of whether 

to revise the MCLG/MCL for 

alachlor, EPA does not believe a 

revision to the NPDWR for alachlor 

is appropriate at this time.
14

Issue

Number of 

Commenters 

and 

Affiliation

General Summary of Comments Disposition of Comment Issues

On October 7, 2009, the Agency 

announced its intent to launch a 

comprehensive new evaluation of 

atrazine to determine its effects on 

humans. At the end of this 

process, the Agency will decide 

whether to revise its current risk 

assessment for atrazine and 

whether new restrictions or 

monitoring requirements are 

necessary to better protect public 

health.

The Agency does not have a 

threshold for occurrence in 

drinking water that triggers a MCL 

revision. There are a number of 

factors considered including, but 

not limited to, the level the 

contaminant is found in drinking 

water, how frequently the 

contaminant is found, the 

geographic distribution, new 

health affects assessments, and 

changes in technology. EPA 

considers all of these factors in 

determining if a revision to a 

NPDWR maintains or strengths 

public health protection. 

Miscellaneous 

comments

1 water 

system

One commenter believes that consumer confidence reports (CCRs) should be 

reviewed as part of the Six-Year Review process. 

The consumer confidence report 

rule is being reviewed under 

Executive Order 13563. In August, 
15

Issue

Number of 

Commenters 

and 

Affiliation

General Summary of Comments Disposition of Comment Issues

2011, EPA released 

“Improving Our Regulations: 

Final Plan for Periodic Retrospective 

Reviews of Existing Regulations”. In 

this plan, EPA defines 35 regulatory 

reviews for our initial review 

period. For more information on 

the plan go to: 

http://www.epa.gov/improvingregu

lations/documents/eparetroreview

plan-aug2011.pdf