United States
Environmental Protection
Agency
Fact Sheet: Announcement of
Completion of EPA's Second Review of
Existing Drinking Water Standards
The Safe Drinking Water Act (SDWA) requires EPA to review each National Primary Drinking
Water Regulation (NPDWR) at least once every six years and revise them, if appropriate. 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 maintain or strengthen public health protection.
Questions and Answers
1. What is the Environmental Protection Agency (EPA) announcing?
In March 2010, the Agency announced the completion of its second review of existing
NPDWRs (i.e., the Six-Year Review 2). After performing a detailed review of 71 existing
NPDWRs, the Agency determined that 67 NPDWRs remain appropriate (i.e., do not need to be
revised) and 4 NPDWRs are candidates for regulatory revision. These four NPDWRs include
acrylamide, epichlorohydrin, tetrachloroethylene, and trichloroethylene. In addition to the 71
NPDWRs, this review includes 14 other NPDWRs that did not need a detailed review because of
recent or ongoing regulatory actions.
2. Why did EPA review these NPDWRs?
The 1996 SDWA Amendments require EPA to periodically review existing NPDWRs and, if
appropriate, revise them. This requirement is contained in Section 1412(b)(9) of SDWA, which
reads:
The Administrator shall, not less often than every 6 years, review and revise, as appropriate,
each national primary drinking water regulation promulgated under this title. Any revision
of a national primary drinking water regulation shall be promulgated in accordance with
this section, except that each revision shall maintain, or provide for greater, protection of
the health of persons.
3. What NPDWRs are covered by this action?
The Six-Year Review process only applies to existing national primary drinking water regulations
(i.e., currently regulated contaminants). Unregulated contaminants, such as those listed on the
Contaminant Candidate List (CCL) are not covered by the Six-Year Review. The current 2003-
2009 review specifically focused on a detailed review of 71 NPDWRs promulgated prior to 2005.
The Agency included 14 other NPDWRs (e.g., lead, copper, disinfection byproducts, and the
microbiological NPDWRs) in the review. However, these regulations did not need a detailed
assessment because they are the subject of recent or ongoing rulemaking activity.
Office of Water (4607M) 815-F-09-002 March 2010
www.epa.gov/safewater
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4. How did EPA review the NPDWRs?
The primary goal of the Six-Year Review is to identify, prioritize and target candidates for
regulatory revision that are most likely to result in a meaningful opportunity for health risk
reduction and/or cost savings to public water systems and their customers while maintaining or
providing for greater levels of public health protection. To address this goal and as part of the
first Six-Year Review (i.e., Six-Year Review 1), EPA developed a protocol to perform the review
based on extensive inputs that included consultations with the National Drinking Water Advisory
Council (NDWAC) and the Science Advisory Board. For Six-Year Review 2, EPA applied the
same protocol with some refinements to improve the tracking of a contaminant through the
decision process.
The protocol focuses on several key elements that are intended to identify NPDWRs for which
there is a health or technological basis for revising the NPDWR. The review relied upon an
evaluation of relevant, new information for the following key technical elements: health effects,
analytical methods improvements, treatment technology effectiveness, occurrence and exposure
analyses, and other potential regulatory changes. Figure 1 provides a general overview of the
protocol used to evaluate the NPDWRs and categorize the results (i.e., revise/take no action).
Figure 1. Six-Year Review Protocol Overview and Major Categories of Revise/Take No Action Outcomes.
NPDWRs Under Review
1
NPDWR reviewed in re
*
Health effects as
in process o
i
cent or ongoing action?
.No
sessment (HEA)
• planned? *
No
New information to suggest possible changes (i.e.,
other regulatory revisions)?
Uncertain - emerging
1 Yes
intormation T
regulator
i
;nt to support
y revision?
Yes | Regulatory action ongoing |
or recently completed
Yes J _ ]
No J . \^
No Data gaps/emerging
information
v J
Yes
Meaningful opportunity for health risk reduction for
persons served by PWS and/or cost savings while
maintaining/improving public health protection?
No Low priority - No meaningful
opportunity
V
~^Y
Outc
No a
_L at thi
^\
\
ome:
ction
s time
/
Yes
•Contaminants with an HEA in process that have an MCL based on practical quantitation
limit and are greaterthan MCLG are passed to the next question to evaluate potential to
revise the MCL. If EPA found that there were no changes in technology (i.e., analytical
feasibility or TT) or if changes were possible but there was no meaningful opportunity to
revise the MCL or TT, these contaminants remained in the ongoing health effects category.
Office of Water (4607M)
www.epa.gov/safewater
815-F-09-002 March 2010
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5. What are the overall review results for Six-Year Review 2?
Based on its review, EPA believes that four NPDWRs are candidates for regulatory revision. These
four NPDWRs are acrylamide, epichlorohydrin, tetrachloroethylene, and trichloroethylene. EPA
believes the remaining 67 NPDWRs are not appropriate for revision due to one or more of the
following reasons:
• A health effects assessment is in process or the Agency is considering whether to initiate
an assessment;
• The NPDWR remains appropriate after review of new, relevant data/information;
• New, relevant information is available that indicate a potential change in the NPDWR
but no revision is recommended because it would result in a negligible gain in public
health protection and/or cost savings; or
• Information gap(s) and/or emerging information were identified.
Table 1 lists EPA's review results for each of the 71 NPDWRs that were a part of this detailed
review along with the principal rationale for the review outcomes. Table 1 also includes a list of the
14 NPDWRs that have been or are being reviewed/revised by recent or ongoing regulatory actions..
6. Will EPA consider reviewing any NPDWRs before the next review cycle?
If the result of any ongoing health risk assessment or the resolution of data gaps/research needs
indicate that significant or compelling new information becomes available that will change the basis
for an NPDWR, the Agency may decide to accelerate the review schedule for a particular NPDWR.
7. What are the next steps?
EPA will consider the public comments and/or any new, relevant, peer-reviewed data submitted for
the four NPDWRs listed as candidates for revision as the Agency proceeds with the regulatory
revisions for these regulations. The announcement that the Agency intends to revise an NPDWR
(pursuant to SDWA section 1412(b)(9)) is not a regulatory decision. Instead, it initiates a
regulatory process that will involve more detailed analyses of health effects, analytical and
treatment feasibility, occurrence, benefits, costs, and other regulatory matters relevant to deciding
whether an NPDWR should be revised. The Six-Year Review results do not obligate the Agency to
revise an NPDWR in the event that EPA determines during the regulatory process that revisions are
no longer appropriate and discontinues further efforts to revise an NPDWR. Similarly, the fact that
an NPDWR has not been selected for revision means only that EPA believes that regulatory
changes to a particular NPDWR are not appropriate at this time for the reasons listed in the answer
to question 5.
8. Where can I find more information about this notice and the Six-Year Review?
For information on the Six-Year Review, please visit the EPA internet website,
www.epa.gov/safewater/review.html. For general information on drinking water, please visit the
EPA Safewater website at www.epa.gov/safewater or contact the Safe Drinking Water Hotline at 1-
Office of Water (4607M) 815-F-09-002 March 2010
www.epa.gov/safewater
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800-426-4791. Local or international calls can reach the Hotline at 703-412-3330. The Safe
Drinking Water Hotline is open Monday through Friday, excluding legal holidays, from 10:00 a.m.
to 4:00 p.m. Eastern time.
Office of Water (4607M) 815-F-09-002 March 2010
www.epa.gov/safewater
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Table 1. Summary of Six- Year Review 2 Results
Recent or Concurrent Action
(14 NPDWRs)
Not Appropriate
for Revision at
this Time
Candidate
for Revision
Health effects assessment in
process or potential nominee for an
assessment
(32 NPDWRs)
NPDWR remains appropriate after
data/information review
(8 NPDWRs)
New
information,
but no
revision
recom-
mended
because:
Low priority
(24 NPDWRs)
Emerging information
or data gaps
(3 NPDWRs)
Based on new information
(4 NPDWRs)
Bromate Cryptosporidium
Chloramines Giardia lamblia
Chlorine HAAS
Chlorine dioxide Lead
Chlorite Legionella
Coliform TTHMs
Copper Viruses
Alpha particles (or emitters)1 Dichloromethane1
Anti mony Di (2-ethyl hexyl)adipate1
Arsenic Di(2-ethylhexyl)phthalate1
Asbestos Ethylbenzene
Benzo(a)pyrene1 Fluoride
Beryllium Nitrate
Beta particles and photon emitters1 Nitrite
Cadmium Pentachlorophenol1
Carbon tetrachloride1 Polychlorinated biphenyls (PCBs)1
Chromium Radiums1
Cyanide Selenium
1,2-Dichlorobenzene Styrene
1,4-Dichlorobenzene 2,3,7,8-TCDD (dioxin)1
1,2-Dichloroethane1 Thallium
cis-1 ,2-Dichloroethylene 1 ,2,4-Trichlorobenzene
trans-1 ,2-Dichloroethylene Uranium
n. , Methoxychlor Monochlorobenzene
|fdoseb (chlorobenzene)
Ethylene Dibromide (EDB) ^Trichorophenoxy-propionic acid
Mercury (inorganic) ' ' ' '
Alarhlor Heptachlor
™'°r Heptachlor epoxide
° Hexachlorobenzene
Benzene , , , , , ...
„,, , Hexach orocyc opentadiene
Chlordane ... y K
. „ _... „ , , Lmdane
1,2-Dibromo-3-chloropropane _ .
(DBCP) °X?myl
A A r^- (.1 ti. i Picloram
1,1-Dichloroethylene T .
1,2-Dichloropropane TcSene
2,4-Dichlorophenoxyacetic acid (2,4- ^™ome[,ane
J. . 1,1,2-Trichloroethane
EnSall XV'enes
Qyphol VinVlchloride
Atrazine 0.
„ , , Simazme
Carbofuran
Acrylamide2 Tetrachloroethylene (PCE)2
Epichlorohydrin Trichloroethylene (TCE)2
1 . For these compounds, there is no potential to change the MCL based on changes in analytical feasibility or there may be a
potential change to the MCL based on analytical feasibility but any such change is unlikely to provide a meaningful opportunity to
improve public health protection. Therefore, EPA chose to leave these in the ongoing health assessment category.
2. Note that a health assessment is in process but new analytical feasibility and TT information may justify a revision
Office of Water (4607M)
www.epa.gov/safewater
815-F-09-002 March 2010
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