Perchlorate

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Summary

TBD.

News Timeline

  • EPA to limit rocket fuel chemical in tap water, Associated press, February 2, 2011.
    • Response from Perchlorate Information Bureau. Response to EPA Decision on Regulating Perchlorate, PRNewswire, February 2, 2011. "According to EPA guidelines, for a federal standard to be warranted on any compound, three criteria must be met:
      • The compound must cause an adverse effect on human health. PIB response: This requirement is not met. To date, no research has shown an adverse effect in humans exposed to perchlorate, and the National Academy of Sciences has concluded that at exposure levels below 245 parts per billion (ppb), there is no effect on the body.
      • The compound must be present in drinking water systems at a frequency and level of public health concern. PIB Response: This requirement is not met. U.S. EPA's own research found that where perchlorate was detected in public drinking water systems, 99 percent of those samples had levels below 6.4 ppb; roughly 40 times lower than the exposure level NAS says has no effect.
      • Regulating the compound must result in a meaningful reduction in risk to public health. PIB Response: This requirement is not met. An actual risk to public health from perchlorate has yet to be scientifically established. A case in point is the 2010 EPA Office of Inspector General report which, among other conclusions, stated, "EPA's perchlorate Reference Dose (RfD) is conservative and protective of public health, and further reducing the perchlorate exposure below the RfD does not effectively lower risk."
  • Statement from the Perchlorate Information Bureau (PIB): California's Proposed Revision to Perchlorate Public Health Goal is Unnecessary, PRNewswire, January 10, 2011.
    • Summary. "The best available science overwhelmingly points to the conclusion that California's current perchlorate public health goal (PHG) of 6 parts per billion in drinking water is exceptionally conservative and highly protective of public health. California's proposed decision to lower the PHG to 1 part per billion would jeopardize water supplies and increase costs for water consumers statewide without any corresponding public health benefit."
    • Existing safe exposure level. "In 2005, a special panel of the National Academy of Sciences (NAS) took the unusual step of suggesting a reference dose (RfD) for perchlorate. The RfD is essentially the daily amount of exposure to a compound that can be considered safe for a lifetime. Standard EPA practice is to determine what level of exposure causes an adverse effect and then apply safety factors to that number to calculate the RfD. As a precaution — no adverse effect level has been identified — NAS took the unprecedented step of starting with a non-adverse effect. NAS further applied a safety factor of ten to this non-adverse effect level to suggest a perchlorate RfD of 24.5 parts per billion.
    • RfD has wide margin of safety built-in. "It's important to understand that exposure to levels above 24.5 ppb, if it occurs, does not suggest a health risk. According to the NAS, you have to have ten times the reference dose to even have a measurable effect, and NAS emphasizes that this first effect is non-adverse. Therefore, any exposure above the reference dose, if it occurs, must be considered in the context of either a non adverse effect, or no effect at all."
  • California Health officials take new aim at perchlorate, Riverside Press-Enterprise, January 9, 2011.
  • California adopts perchlorate standard, American Water Works Association, September 22, 2007.

Studies and Reports

  • Tarone R et al., The epidemiology of environmental perchlorate exposure and thyroid function: a comprehensive review, J Occup Environ Med. 2010 Jun;52(6):653-60.
    • Conclusion. "There is no epidemiologic evidence that environmental or occupational exposure to perchlorate adversely affects thyroid function in the United States. Even if all perchlorate could be removed from the environment, >99% of the inhibition of iodide uptake in the thyroid resulting from exposure to environmental goitrogens would remain."
  • Buffler P et al., Thyroid function and perchlorate in drinking water: an evaluation among California newborns, 1998, Environ Health Perspect. 2006 May;114(5):798-804..
    • Abstract. "Perchlorate (ClO4-) has been detected in groundwater sources in numerous communities in California and other parts of the United States, raising concerns about potential impacts on health. For California communities where ClO4- was tested in 1997 and 1998, we evaluated the prevalence of primary congenital hypothyroidism (PCH) and high thyroid-stimulating hormone (TSH) levels among the 342,257 California newborns screened in 1998. We compared thyroid function results among newborns from 24 communities with average ClO4- concentrations in drinking water>5 microg/L (n=50,326) to newborns from 287 communities with average concentrations<or=5 microg/L (n=291,931). ClO4- concentrations obtained from the California Drinking Water Program provided source-specific data for estimating weighted average concentrations in community water. Fifteen cases of PCH from communities with average concentration>5 microg/L were observed, with 20.4 expected [adjusted prevalence odds ratio (POR)=0.71; 95% confidence interval (CI), 0.40-1.19]. Although only 36% of all California newborns were screened before 24 hr of age in 1998, nearly 80% of newborns with high TSH were screened before 24 hr of age. Because of the physiologic postnatal surge of TSH, the results for newborns screened before 24 hr were uninformative for assessing an environmental impact. For newborns screened>or=24 hr, the adjusted POR for high TSH was 0.73 (95% CI, 0.40-1.23). All adjusted odds ratios (ORs) were controlled for sex, ethnicity, birth weight, and multiple birth status. Using an assessment of ClO4- in drinking water based on available data, we did not observe an association between estimated average ClO4- concentrations>5 microg/L in drinking water supplies and the prevalence of clinically diagnosed PCH or high TSH concentrations."

Additional Resources

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