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New Research on Perchlorate and Food

As the public, regulators and the media consider the findings of the new study by Sanchez, et al., "Perchlorate exposure from food crops produced in the lower Colorado River region," some key facts about the study must be understood so the findings are not mischaracterized.

First, the authors state the findings are based on a hypothetical analysis. Second, the authors emphasize that excedance of the perchlroate reference dose (RfD) suggested by the National Academy of Sciences, if it occurs, is rare.  Third, many of the foods examined are also high in iodine, which the authors suggest could decrease the effect of perchlorate, but the effect of iodine was not considered in their analysis. 

In addition, a few key excerpts taken directly from the study must be considered:

• "... our estimates of exposure agree closely with those exploratory data reported by the FDA (FDA, 207; Murray et al., 2008) for similar population groupings."  Importantly, the FDA, following the completion of its own research, indicated no change in diet was necessary.  See FDA's most recent Q&A on perchlorate, updated 1-8-09 at http://www.cfsan.fda.gov/~dms/clo4qa.html#alterdiet ) .
• "Consumption of milk, vegetables and fruit is encouraged by the USDA (USDA 2005) as part of a healthy and nutritionally balanced diet and avoiding milk, fresh fruits and vegetables due to trace levels of perchlorate is not advised."
• Researchers ran their exposure assessments assuming 0, 6 and 14 parts per billion (ppb) perchlorate in drinking water.  Regarding the 6 and 14 ppb amounts, researchers wrote: "These two sensitivity analyses should be viewed with caution because very few individuals drink water that contains perchlorate at these concentrations.  Thus exposure estimates derived in these sensitivity analyses are expected to result in unrepresentative (conservative) exposure estimates."
• "Current data indicate that perchlorate in drinking water seldom exceeds 4 ppb in drinking water in the United States, and thus few individuals would likely be exposed to perchlorate doses exceeding the RfD, whether consuming produce within or outside the Lower Colorado River region."

An additional consideration is the question of whether excedance of the RfD, if it occurs, constitutes a health risk.  The perchlorate RfD is based upon a ten-fold safety factor that was applied to a dose of perchlorate that had no measurable effect, according to the NAS.   In short, the NAS found that perchlorate levels as high as 245 parts per billion had no measurable effect, but in an abundance of caution, set the RfD at one-tenth this amount.   

Finally, a study by Amitai, et al., provides further evidence that the NAS reference dose is conservative and health protective to the most sensitive individuals in the population.  This study,  conducted in Israel in 2007, looked at the effect among newborns whose mothers lived in areas with perchlorate in the drinking water.  Mothers in the highest exposure group (340 ppb) showed no difference in thyroid hormone compared to the control group or compared to mothers in the midrange exposure group who consume between 42 and 94 ppb in water. 

To review the full study, click here.

For more on this topic, visit www.perchlorateinformationbureau.org. 

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The Perchlorate Information Bureau is supported by Aerojet, American Pacific Corporation, and Lockheed Martin. These companies have worked cooperatively with the U.S. Environmental Protection Agency to increase scientific and medical understanding of perchlorate's risk to human health.