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

Abstract

Estimates of perchlorate intake by the US population can be derived from either urinary excretion data or through simulation of dietary intake. Estimates from surveys of urinary excretion (NHANES) are subject to substantial uncertainty owing to the small numbers of subjects for which data are currently available. In addition, current excretion estimates are derived from ''spot'' urine samples and include a component of short-term (intra-day) variability that may give biased estimates of the variability in average daily intakes. Previous dietary estimates have generally not included any contribution from drinking water, owing to a lack of data related to perchlorate concentrations in water supplies. In this paper, we derive simulation (Monte Carlo) estimates of dietary perchlorate intake distributions for reproductive-age women, which include explicit contributions from drinking water, and compare them to estimates based on urinary excretion. Perchlorate concentrations in water were estimated based on measurements from the US Environmental Protection Agency's UCMR1 database, and from other regional studies of perchlorate contamination. We find that including the drinking water contributions in the dietary simulations yields increases in the population's geometric mean perchlorate intake of 3-8 percent, with a conservative maximum of about 24 percent, compared to intakes estimated based on food intake alone. The intake distributions estimated from dietary and water consumption were found to be very similar to estimates based on creatinine-adjusted perchlorate excretion data from the NHANES, except for having lower population variability. When the dietary simulation data were adjusted to include a contribution from short-term variability similar to that in the ''spot'' urine samples, the variability in the NHANES and diet-derived estimates were found to be very similar. Our analyses indicate that a reasonable upper-bound estimate for the 95th percentile perchlorate intake among women of reproductive age in the US is on the order of 1.5 Â 10 À4 mg/kg/day.

Perchlorate, Nitrate, and Iodide Intake through Tap Water

“…Similarly, Huber et al estimated total perchlorate dose and the percentage of dose attributable to tap water and found that 14% of the median perchlorate dose for both adults and women of reproductive age resulted from tap water intake (23). Our findings are also consistent with Mendez et al's study which used Monte Carlo simulations to estimate the perchlorate dose, found that tap water consumption to be a minor contributor to total perchlorate dose (49,50). Finally, our estimates of perchlorate intake attributable to total tap water consumption were an order of magnitude lower than perchlorate intake dose attributable to diet (51).…”

Thyroid antagonists and thyroid indicators in U.S. pregnant women in the Vanguard Study of the National Children's Study

“…Huber et al (2011) used National Health and Nutrition Examination Survey (NHANES) data and estimated that approximately 80% of urinary perchlorate was derived from dietary sources. Others also have shown diet as the primary perchlorate exposure source for U.S. residents, based on tap water perchlorate concentrations (Mendez et al, 2010), dietary analysis (Murray, et al 2008), and analysis of tap water and exposure data from NHANES (Blount et al, 2010; Lau et al, 2013; Yang et al, 2012). …”

Urinary perchlorate as a measure of dietary and drinking water exposure in a representative sample of the United States population 2001–2008

“…8,33,34 Murray et al 21 estimated dietary perchlorate intake by multiplying perchlorate levels in food by age-appropriate food consumption rates; the estimated mean intake was below the RfD for all age groups, from infants to adults. 20 Another study reached the same conclusion by modeling aggregate perchlorate exposure based on food and tap water perchlorate levels. 20 Recently, Huber et al 35 estimated total perchlorate dose attributable to tap water based on merging data from National Health and Nutrition Examination Survey (NHANES) and UCMR1; they found that among participants exposed to perchlorate from food and tap water, 23.7% of median perchlorate intake was attributable to tap water consumption.…”

“…20 Another study reached the same conclusion by modeling aggregate perchlorate exposure based on food and tap water perchlorate levels. 20 Recently, Huber et al 35 estimated total perchlorate dose attributable to tap water based on merging data from National Health and Nutrition Examination Survey (NHANES) and UCMR1; they found that among participants exposed to perchlorate from food and tap water, 23.7% of median perchlorate intake was attributable to tap water consumption. 35 Our study adds to this literature by characterizing the relative importance of perchlorate exposure from food and tap water for the US population based on dietary questionnaire data and urinary perchlorate levels from NHANES 2001 to 2008.…”

“…13 The presence of perchlorate in the environment leads to contamination in certain types of foods. 11,[14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] The Food and Drug Administration (FDA) Total Diet Study in 2005-2006 found perchlorate in numerous food groups: dairy products, fruits, and vegetables were identified as the primary sources of perchlorate exposure. 21 Other studies have also found perchlorate in fruits and vegetables 11,16,17,19,[22][23][24][25]27,31 and dairy products.…”