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2 fa ey UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
PANY JAE WASHINGTON, D.C. 20460
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"Al pore?
JAN 11 2001
MEMORANDUM

SUBJECT: Guidance for Public Water Systems on Enhanced Monitoring for Chromiums6 "

(Hexavalent Chromium) in Drinking Water

FROM: Peter S. Silva x |
Assistant Administrator

TO: State Drinking Water Agencies
PWS Owners and Managers
Drinking Water Program Managers, Region I-X

EPA appreciates and acknowledges your continued efforts to ensure that all Americans
have safe drinking water. Chromium is one of over 90 regulated drinking water contaminants
that we have worked together to address. However, recent studies indicate the potential for
greater human health risks from chromium-6 (the more toxic form of chromium) than was
previously thought. We are peer reviewing our assessment of the new health data, and will
evaluate the final assessment in accordance with the Safe Drinking Water Act to determine if
new standards need to be set.

Given this emerging public health information, EPA is providing this guidance to all
public water systems to see how a system could enhance chromium monitoring through
additional sampling and analysis specifically for chromium-6. The Agency strongly encourages
water systems to consider the recommendations provided on our website (http:
//water.epa.gov/drink/info/chromium/index.cfm) and to determine how your system might
enhance drinking water monitoring for chromium-6.

National primary drinking water regulations set the maximum contaminant level (MCL)
of 0.1 mg/L for total chromium, which includes chromium-6, and requires community and non-
transient non-community water systems to test for chromium at the entry point to the distribution
system, The chromium standard was established in 1991 based on the best available science.
EPA regularly re-evaluates drinking water standards; a rigorous and comprehensive review of
chromium-6 health effects began following the release of the toxicity studies by the National
Toxicology Program in 2008. In September, 2010, EPA released a drafi of the scientific
assessment (Toxicological Review of Hexavalent Chromium
http://cfpub.epa.gov/ncea/iris_dratis/recordisplay.cfm?deid=221433) for public comment and
external peer review. When this human health assessment is finalized in 2011, EPA will
carefully review the conclusions and consider all relevant information to determine if a new
standard needs to be set.

Internet Address (URL) + http:/www.epa.gov
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In the interim period, EPA is providing guidance to water systems on how they may
monitor for chromium-6 in addition to the monitoring they are required to perform for total
chromium. EPA believes that the enhanced monitoring will enable public water systems to:
better inform their consumers about the levels of chromium-6 in their drinking water, evaluate
the degree to which other forms of chromium are transformed into chromium-6 in their drinking
water and assess the degree to which existing treatment affects the levels of chromium-6 in
drinking water. We appreciate your support and look forward to working with you through an
increased dialogue between EPA, states, public water systems and the public on issues related to
chromium-6.