FDA Analysis of Perchlorate in Food
Having considered the science relating to potential human health effects of perchlorate ingestion, the U.S. Food and Drug Administration (FDA), to date, continues to recommend that consumers not alter their infant's or child's diet.
Nonetheless, public statements from sources outside FDA have erroneously characterized the findings of a recent FDA study on perchlorate in food. In particular, there appears to be confusion about what the study's findings might mean in the context of a perchlorate "reference dose."
Following are a few pertinent facts to help ensure the record is accurate:
- A reference dose (RfD) is the amount of a substance determined by regulatory agencies to be safe for anyone, regardless of age, to consume daily over a lifetime.
- The proposed perchlorate RfD is based on an authoritative analysis by the National Academy of Sciences. The NAS analysis, based on a comprehensive review of the scientific literature, supplemented by public hearings and testimony, determined that perchlorate had no observable health effect at levels as high as 245 parts per billion (ppb); the NAS analysis further stated that any effect at this level was not harmful. In an abundance of caution to ensure a margin of safety for vulnerable subpopulations, including pregnant and nursing mothers and their children, the Academy applied a ten-fold safety factor to suggest a perchlorate RfD of 24.5 ppb. Importantly, this is based exclusively on administered doses of perchlorate used in clinical studies, and is more conservative than if it had considered pre-existing background exposures to perchlorate from food.
- No credible, peer-reviewed studies have been published to date that suggest perchlorate levels below 245 ppb pose a risk of adverse health effects.
- No one in FDA's new dietary analysis was shown to be consuming perchlorate at levels above the reference dose. Statements that anyone, including children, might be exposed to unsafe levels of perchlorate from food are inconsistent with the science and simply incorrect.
- Some have raised the question of whether perchlorate exposure from food and water exceeds safe levels--but the facts indicate otherwise. U.S. EPA recently collected 34,193 water samples from public water systems, of which exactly 160 systems had levels of perchlorate at or above 4 ppb and the average detection was 9.85 ppb. It can therefore be reasonably estimated that combined exposure from food and water remains below the RfD. Even if it did not, however, the fact remains that exposure above 24.5 ppb must be considered in the context of a non-adverse effect (see point #2 above).
- The chief concern about perchlorate exposure is whether it blocks the body's ability to absorb iodine, which it uses to make thyroid hormones. More specifically, the impacts of perchlorate exposure will vary depending on an individual's iodine sufficiency. FDA has found foods which contain perchlorate generally contain higher levels of iodine. Thus there is evidence that foods consumed with the highest perchlorate content are also those with correspondingly high iodine content, but no evidence that toddlers, children or adults are iodine deficient. In fact, the FDA study confirms that sufficient iodine is present in food to meet established health levels.
- To view FDA's latest QSA on perchlorate and food, please log onto www.cfsan.fda.gov/~dms/clo4qa.html