EPA Takes Comments Again on Perchlorate

The U.S. Environmental Protection Agency is asking for comments again on whether it should regulate perchlorate according to amended section 1412 of the Safe Drinking Water Act.

To regulate a contaminant in drinking water, EPA must determine it meets three criteria. Last year, the agency announced that perchlorate did not meet the second and third criteria. This triggered a cascade of 32,975 comment letters, 96 percent of which were mass-mailed opposing letters, EPA said in Wednesday's announcement of a new comment period, which will end Sept. 18.

These are the criteria:

  • The contaminant may have an adverse effect on human health,
  • the contaminant is known to occur or there is a substantial likelihood that the contaminant will occur in public water systems with a frequency and at levels of public health concern, and
  • regulation of such contaminant presents a meaningful opportunity for health risk reduction for persons served by public water systems.

To date, EPA has made final regulatory determinations for 20 contaminants but none of these meets all three criteria.

The agency said it was left with 1,163 comment letters that would be considered "unique," with 30 of them providing detailed comments and six of those supporting the preliminary determination.

"These additional comments are sought in an effort to ensure consideration of all the potential options for evaluating whether there is a meaningful opportunity for human health risk reduction of perchlorate through a national primary drinking water rule," EPA's release states.

The relevant comments questioned EPA's use of its Physiologically-Based Pharmacokinetic (PBPK) model to estimate the iodide uptake inhibition for these sensitive life stages -- the pregnant woman and fetus, the lactating woman and neonate, and the young child -- consuming food and drinking water containing perchlorate. Based on comments received, the agency said it is re-evaluating how best to incorporate the PBPK modeling analysis into its evaluation of perchlorate, if at all.

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