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Six-Year Review 2 of Drinking Water Standards

Six-Year Review & Other Related Links

In March 2010, the Agency announced the review results for the Agency’s second Six-Year Review (called Six-Year Review 2).  After performing a detailed review of 71 National Primary Drinking Water Regulations (NPDWRs), the Agency believes that 67 NPDWRs remain appropriate (i.e., do not need to be revised) and four NPDWRs are candidates for regulatory revision.  These four NPDWRs include acrylamide, epichlorohydrin, tetrachloroethylene, and trichloroethylene.  In addition to the 71 NPDWRs reviewed in detail for the Six-Year Review 2, 14 other NPDWRs were included in the review but did not need a detailed review because of recent or ongoing regulatory actions (i.e., DBPs, lead and copper, and microbials).

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Announcement of the Completion of EPA's Second Review of Existing Drinking Water Standards

Summary of Six-Year Review 2 Results

The following table provides a summary of the Six-Year Review 2 results for each of the 71 NPDWRs that were reviewed in detail as part of the Six-Year Review 2 effort.

Summary of Six-Year Review 2 Results
Summary of Review outcomes Contaminants
Recent or Ongoing Action (14 NPDWRs) Bromate
Chloramines
Chlorine
Chlorine dioxide
Chlorite
Coliform
Copper
Cryptosporidium
Giardia lamblia
HAA5
Lead
Legionella
TTHMs
Viruses
Not Appropriate for Revision at this Time Health effects assessment in process or potential nominee for an assessment (32 NPDWRs) Alpha particles (or emitters)1
Antimony
Arsenic
Asbestos
Benzo(a)pyrene1
Beryllium
Beta particles and photon emitters1
Cadmium
Carbon tetrachloride1
Chromium
Cyanide
1,2-Dichlorobenzene
1,4-Dichlorobenzene
1,2-Dichloroethane1
cis-1,2-Dichloroethylene
trans-1,2-Dichloroethylene
Dichloromethane1
Di(2-ethylhexyl)adipate1
Di(2-ethylhexyl)phthalate1
Ethylbenzene
Fluoride
Nitrate
Nitrite
Pentachlorophenol1
Polychlorinated biphenyls (PCBs)1
Radiums1
Selenium
Styrene
2,3,7,8-TCDD (dioxin)1
Thallium
1,2,4-Trichlorobenzene
Uranium
NPDWR remains appropriate after data/information review(8 NPDWRs) Dalapon
Dinoseb
Endrin
Ethylene Dibromide (EDB)
Mercury (inorganic)
Methoxychlor
Monochlorobenzene (chlorobenzene)
2,4,5-Trichorophenoxy-propionic acid (2,4,5-TP)
New information, but no revision recommended because: Low priority
(24 NPDWRs)
Alachlor
Barium
Benzene
Chlordane
1,2-Dibromo-3-chloropropane (DBCP)
1,1-Dichloroethylene
1,2-Dichloropropane
2,4-Dichlorophenoxyacetic acid (2,4-D)
Diquat
Endothall
Glyphosate
Heptachlor
Heptachlor epoxide
Hexachlorobenzene
Hexachlorocyclopentadiene
Lindane
Oxamyl
Picloram
Toluene
Toxaphene
1,1,1-Trichloroethane
1,1,2-Trichloroethane
Xylenes
Vinyl chloride

Emerging information or data gaps
(3 NPDWRs)

Atrazine
Carbofuran
Simazine
Candidate for Revision Based on new information (4 NPDWRs) Acrylamide2
Epichlorohydrin
Tetrachloroethylene (PCE)2
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.

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