[CPEO-MEF] Brief analysis of EPA's new perchlorate guidance

[Lenny Siegel <lsiegel@cpeo.org>]

On Thursday, January 26, U.S. EPA issued a guidance setting the 
"preliminary remediation goal" for perchlorate in water at 24.5 parts 
per billion. (See http://epa.gov/newsroom/perchlorate.pdf.) This is NOT 
a promulgated drinking water standard, also known as a Maximum 
Contaminant Level (MCL). Rather, this number replaces the 4 to 18 parts 
per billion in EPA's previous Interim Guidance.

Unlike the MCL, which is supposed to take contributions from other 
sources into account, the preliminary remediation goal is supposed to be 
used in the remedial investigation/feasibility stage under CERCLA 
(Superfund Law) cleanups. The guidance explains, "For example, the RI 
[Remedial Investigation] may indicate that individuals at a site may be 
exposed to perchlorate through multiple pathways. In such cases, 
contribution from non-water sources should be considered based on 
site-specific data until further national guidance on relative source 
contribution is developed."

The Guidance asserts that it will protect vulnerable populations. For 
example, it states,  "In addition, the Agency's practice of using the 
RfD [Reference Dose] to calculate a DWEL [Drinking Water Equivalent 
Level] for perchlorate using a 70 kg body weight and a water consumption 
value of 2 L/day is further supported in this instance by the fact that 
the standard weight and consumption values also represent weight and 
consumption values relevant for protecting the most sensitive population."

That doesn't make sense to me. It my understanding that some of those 
sensitive populations, newborns and young children, drink much more 
water for their body weight than 70 kg adults.

Given the recent political history of perchlorate science, EPA's 24.5 
number is not surprising. It represents a victory for the Defense 
Department and other polluters that have lobbied and sponsored research 
designed to weaken EPA's proposed standard, which at one point was as 
low as one part per billion.

The new cleanup goal won't influence requirements for drinking water 
treatment, because it is not a drinking water standard. It won't bring 
existing remedial action to a halt, because most sites with major 
perchlorate cleanup programs have hot spot concentrations in the 
hundreds or even thousands of parts per billion. But it may wipe other 
perchlorate contamination sites - such as military ranges - off the map, 
because many of those have maximum reported concentrations under 24.5 
parts per billion. Only in states that establish more protective goals, 
as California and Massachusetts have proposed, will such sites be 
investigated and remediated.

Lenny Siegel

--
Lenny Siegel
Director, Center for Public Environmental Oversight
c/o PSC, 278-A Hope St., Mountain View, CA 94041
Voice: 650/961-8918 or 650/969-1545
Fax: 650/961-8918
http://www.cpeo.org

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