Perchlorate Exposure and Dose Estimates in Infants

Abstract

Perchlorate is a naturally occurring inorganic anion used as a component of solid rocket fuel, explosives, and pyrotechnics. Sufficiently high perchlorate intakes can modify thyroid function by competitively inhibiting iodide uptake in adults; however little is known about perchlorate exposure and health effects in infants. Food intake models predict that infants have higher perchlorate exposure doses than adults. For this reason, we measured perchlorate and related anions (nitrate, thiocyanate, and iodide) in 206 urine samples from 92 infants ages 1–377 days and calculated perchlorate intake dose for this population of infants. The median estimated exposure dose for this population of infants was 0.160 μg/kg/day. Of the 205 individual dose estimates, 9% exceeded the reference dose of 0.7 μg/kg/day; 6% of infants providing multiple samples had multiple perchlorate dose estimates above the reference dose. Estimated exposure dose differed by feeding method: breast-fed infants had a higher perchlorate exposure dose (geometric mean 0.220 μg/kg/day) than infants consuming cow milk-based formula (geometric mean 0.103 μg/kg/day, p<0.0001) or soy-based formula (geometric mean 0.027 μg/kg/day, p<0.0001), consistent with dose estimates based on dietary intake data. The ability of perchlorate to block adequate iodide uptake by the thyroid may have been reduced by the iodine-sufficient status of the infants studied (median urinary iodide 125 μg/L). Further research is needed to see whether these perchlorate intake doses lead to any health effects.

Placental transfer of and infantile exposure to perchlorate

“…2). Furthermore, our DOSE M values were an order of magnitude greater than those reported in the U.S. (Leung et al, 2012;Valentin-Blasini et al, 2011), however, our results on the influence of dietary habits on perchlorate exposure by infants are similar to that found in the U.S. . Although the majority of studied infants in this study had exposure dose of perchlorate exceeding RfD, the estimations of DOSE U and DOSE M has certain uncertainty by using spot urine and breast milk samples, respectively.…”

“…1), but were much lower than those in maternal (mean: 13.2 ± 1.70 ng mL À1 ) and cord serum (19.9 ± 5.00 ng mL À1 ) samples obtained in a city of Chile (Lumen et al, 2013). However, it should (Asami et al, 2013;Blount et al, 2009;Borjan et al, 2011;Dasgupta et al, 2008;Her et al, 2010;Kirk et al, 2007;Kirk et al, 2005;Kirk et al, 2012;Lee et al, 2012;Leung et al, 2012;Leung et al, 2009;Lumen et al, 2013;Pearce et al, 2007;Wang et al, 2011;Valentin-Blasini et al, 2011). In this study, breast milk and infants' urine were recruited in Nanchang; cord blood samples were obtained in Tianjin; infant formula samples from ten manufacturers representing >80% of the Chinese market were purchased from retail stores.…”

“…1. To our knowledge, nearly all previously studies on perchlorate in the breast milk, infant formula and urine of infants were from the U.S. (Borjan et al, 2011;Dasgupta et al, 2008;Kirk et al, 2007Kirk et al, , 2012Kirk et al, , 2005Leung et al, 2012;Leung et al, 2009;Pearce et al, 2007;Valentin-Blasini et al, 2011), but several studies reported perchlorate concentrations in infant formula from Canada (Wang et al, 2011), Korea (Her et al, 2010;Lee et al, 2012) and Japan (Asami et al, 2013). The urinary concentrations of perchlorate that were detected among all infants from Nanchang, China were up to 20 (range: 2e20) fold higher than those of American infants (Fig.…”

Environmental Perchlorate and Thiocyanate Exposures and Infant Serum Thyroid Function

“…Infants and children have the highest estimated intakes of perchlorate by body weight (33), with urinary perchlorate levels < 0.05-25.8 lg/L in 92 U.S. infants in a recent study (34). In the NHANES data from 2001-2002, perchlorate was detected in all 2820 spot urine samples (median urine perchlorate concentration 3.6 lg/L) (11) and was a significant negative predictor of total T4 and a positive predictor of TSH values in women, primarily those with urine iodine concentrations < 100 lg/L (35).…”

Iodine Deficiency, Pollutant Chemicals, and the Thyroid: New Information on an Old Problem

“…Although such transport might be expected to lead to increased concentrations of nitrate, thiocyanate, and perchlorate in human milk, only perchlorate exposure and excretion have been found to be significantly higher in breastfed infants under normal circumstances. 13,14 Thiocyanate and nitrate are wellknown and commonly encountered chemicals. Exposure to thiocyanate comes from cruciferous vegetables and tobacco smoke (including secondhand smoke), and exposure to nitrate comes from drinking water and some leafy and root vegetables.…”