A recent study by Schier, et al., “Perchlorate exposure from infant formula and comparisons with the perchlorate reference dose,” has raised a question over whether, in certain scenarios, infants being fed with some brands of formula might exceed the perchlorate Reference Dose (RfD) suggested by the National Academy of Sciences.
This question underscores two important points. First is the importance of ensuring that all of the best available science, rather than individual studies, is used in making regulatory decisions. Second, and equally fundamental, is the question of whether excedance of the RfD, if it occurs, constitutes a health risk. Indeed, the authors of the Schier study themselves state:
- “The potential health risks associated with exceeding the perchlorate RfD in infants is currently unknown.”
- “… the lack of any overt, large scale effect (of exceeding the perchlorate RfD) as evidenced by the aforementioned studies (Crump et al., Tellez, et al., Kirk, et. al., Pearce et al.) is reassuring.”
- “Although the perchlorate RfD may be exceeded in some specific situations, the clinical relevance of this is unclear.”
- “Further work is needed to clarify both the complex interrelationships among the thyroid, perchlorate, and iodide as well as any potential public health risk with exceeding the
perchlorate RfD.”
What makes these excerpts especially relevant is the fact that 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., conducted in Israel in 2007, looked at the effect among newborns whose mothers lived in areas where perchlorate levels in drinking water were as low as 3 parts per
billion (ppb) and as high as 340 parts per billion. The study found no differences in key hormone levels among any of the newborns, providing evidence that the NAS reference dose is conservative and health protective to the most sensitive individuals in the population.
The CDC has also provided a fact sheet on its study, available at: http://www.cdc.gov/nceh/features/perchlorate_factsheet.htm.
For more on this topic, visit www.perchlorateinformationbureau.org.