^aCenter for Food Safety and Applied Nutrition, US Food and Drug Administration, College Park, Maryland, USA

Correspondence: Dr. Clarence William Murray, Center for Food Safety and Applied Nutrition, US Food and Drug Administration, 5100 Paint Branch Parkway, HFS-301, College Park, MD 20740-3835, USA. Tel.: +1 301 436 1944; Fax: +1 301 436 2632; E-mail: Clarence.Murray@fda.hhs.gov

Received 7 September 2007; Accepted 5 November 2007; Published online 2 January 2008.

Abstract

The US Food and Drug Administration (FDA) has conducted the Total Diet Study (TDS) since 1961, which designed to monitor the US food supply for chemical contaminants, nutritional elements, and toxic elements. Recently, perchlorate was analyzed in TDS samples. Perchlorate is used as an oxidizing agent in rocket propellant, is found in other items (e.g., explosives, road flares, fireworks, and car airbags), occurs naturally in some fertilizers, and may be generated under certain climatic conditions. It has been detected in surface and groundwater and in food. Perchlorate at high (e.g., pharmacological) doses can interfere with iodide uptake into the thyroid gland, disrupting its function. The National Academy of Sciences (NAS) has identified that "the fetuses of pregnant women who might have hypothyroidism or iodide deficiency as the most sensitive population." This study reports on intake estimates of perchlorate and iodine, a precursor to iodide, using the analytical results from the TDS. Estimated average perchlorate and iodine daily intakes as well as the contribution of specific food groups to total intakes were estimated for 14 age/sex subgroups of the US population. The estimated smallest lower bound to the largest upper bound average perchlorate intakes by the 14 age/sex groups range from 0.08 to 0.39 micrograms per kilogram body weight per day (g/kg bw/day), compared with the US Environmental Protection Agency (EPA) reference dose (RfD) of 0.7 g/kg bw/day. Infants and children demonstrated the highest estimated intakes of perchlorate on a body weight basis. The estimated average iodine intakes by the 14 age/sex groups reveal a lower bound (ND=0) and upper bound (ND=LOD) range of average intakes from 138 to 353 g/person/day. Estimated iodine intakes by infants 6–11 months exceed their adequate intake (AI), and intakes by children and adult age/sex groups exceed their relevant estimated average requirement (EAR).