EWG Calls on EPA to Set Lower Limit on Perchlorate in Water

Environmental Working Group commends the EPA for taking action to protect Americans from perchlorate, the endocrine-disrupting compound that has long been an important public health issue.

EWG strongly objected to the EPA’s 2008 preliminary determination that regulating perchlorate in drinking water would not meaningfully reduce the risks to health, and we are gratified that the agency reversed this erroneous position.

We remain disappointed, however, that the EPA has not revised the current reference dose (RfD) for perchlorate, given that the agency’s own Children’s Health Protection Advisory Committee deemed the RfD inadequate and that a large 2006 study by the Centers for Disease Control and Prevention found anti-thyroid effects at lower exposure levels.

We are encouraged that the EPA has used life stage-specific exposure factors in the development of its Maximum Contaminant Level Goals (MCLG), but these Goals cannot be considered truly health protective as long as they are based on a flawed reference dose. We urge the agency to keep this in mind as it moves to set a final drinking water standard for perchlorate.

It goes without saying that the EPA should use bottle-fed infants (rather than pregnant women or breast-fed infants) as the basis for deriving the standard, inasmuch as the agency’s calculations indicate that this is the most highly exposed sensitive sub-population. According to EPA’s May 2012 white paper, combining the flawed reference dose with life stage-specific exposure factors for bottle-fed infants would put the MCLG at 2 parts per billion. A corrected reference dose would result in an even lower goal.

EWG also urges the EPA to revamp its laboratory method for measuring perchlorate, which currently cannot detect concentrations as low as 2 ppb. We know that a lower Minimum Reporting Level is achievable because Massachusetts adopted a 1 ppb level for perchlorate in 2006, and the technology can only have improved over the last six years.

Similarly, we know that drinking water standards in the low parts-per-billion range are also technically and economically feasible because Massachusetts and California have already set drinking water standards of 2 ppb and 6 ppb, respectively. While the extent of perchlorate contamination in Massachusetts is relatively low, California has one of most widespread problems in the nation and recently proposed a revised Public Health Goal of 1 ppb for perchlorate. If this is finalized, the state is expected to lower its drinking water standard.

It has now been two decades since the EPA issued its first provisional reference dose for perchlorate. EWG urges the agency to act quickly to set a truly health-protective drinking water standard lower than 1 ppb for this widespread toxin, and certainly no higher than the 2 ppb MCLG that EPA is currently proposing.

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