US Food and Drug Administration's Total Diet Study: Dietary intake of perchlorate and iodine

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 (mg/kg bw/day), compared with the US Environmental Protection Agency (EPA) reference dose (RfD) of 0.7 mg/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 ¼ 0) and upper bound (ND ¼ LOD) range of average intakes from 138 to 353 mg/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).

Drinking water contribution to aggregate perchlorate intake of reproductive-age women in the United States estimated by dietary intake simulation and analysis of urinary excretion data

“…Consistent with findings from previous studies or perchlorate concentrations in foods (Jackson et al, 2005;Sanchez et al, 2005a;Sanchez et al, 2005b;Murray et al, 2008;Sanchez et al, 2008), results from our dietary simulations suggest that drinking water contamination accounts for a relatively small proportion of total population intake for reproductive-age women in the United States. As shown in Table 5, addition of reasonable assumed drinking water perchlorate distributions increases the central tendency (mean and median) estimates of national perchlorate intakes for reproductive-age women by between approximately 3 and 24%.…”

“…The former estimates are very close to our mean and 90th percentile intake estimates of 6.3 Â 10 À5 and 1.2 Â 10 À4 mg/kg/day for dietary consumption, including dairy products. Murray et al (2008) derived point estimates of national perchlorate intake by reproductive-age women and other groups based on data from the most recent (2005)(2006) Total Dietary Survey perchlorate concentration data and consumption amounts from the 1996-1998 CSFII. They estimated ''lower-bound'' and ''upper-bound'' mean perchlorate intakes for women aged between 25 to 45 years to be 9 Â 10 À5 and 1.1 Â 10 À4 mg/kg/day.…”

Influence of iodide ingestion on nitrate metabolism and blood pressure following short-term dietary nitrate supplementation in healthy normotensive adults

“…The recommended adequate daily intake (ADI) for I -is 150 μg for adult males and females, and 200 μg during pregnancy and lactation [53]. These doses could readily be achieved through a diet rich in seafood and dairy products [34], but the I -dose administered in this study (450 μg·day -1 ) exceeded the upper range of average daily I -in the USA where iodised salt is mandated [54]. However, despite administering a large I -dose in this study (i.e., an I -dose that is not likely to be achieved by most individuals through the diet), the increase in plasma [NO 2 -] and the lowering of blood pressure after NO 3 -supplementation were not different with or without co-ingestion of I -.…”

Iodine Status in Pregnant Women in the National Children's Study and in U.S. Women (15–44 Years), National Health and Nutrition Examination Survey 2005–2010

“…Dairy, grain, seafood, and to a lesser degree, iodized salt are the major sources of iodine in the United States (5). However, there is a wide variation in iodine content in foods and iodine content is rarely included in nutritional labeling (5).…”