Predicting Perchlorate Exposure in Milk from Concentrations in Dairy Feed

Abstract

Perchlorate has been detected in U.S. milk samples from many different states. Applying data from a recently reported 9-week experiment in which 16 Holstein dairy cows were administered perchlorate allowed us to derive an equation for the dose-response relationship between perchlorate concentrations in feed/drinking water and its appearance in milk. Examination of background concentrations of perchlorate in the total mixed ration (TMR) fed in addition to the variable dose supplied to treated cows as a ruminal infusate revealed that cows receive significant and variable exposure to perchlorate from the TMR. Weekly examination of the TMR disclosed that a change in ingredients midway through the experiment caused a significant (78%) change in TMR perchlorate concentration. Analyses of the ingredients comprising the TMR revealed that 41.9% of the perchlorate came from corn silage, 22.9% came from alfalfa hay and 11.7% was supplied by sudan grass. Finally, USDA Food and Nutrition Survey data on fluid milk consumption were used to predict potential human exposure from milk that contained concentrations of perchlorate observed in our previous dosing study. The study suggests that reducing perchlorate concentration in dairy feed may reduce perchlorate concentrations in milk as well as the potential to reduce human exposure to perchlorate in milk.

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

“…18,21,43,44 Perchlorate can bioaccumulate in milk because perchlorate absorbed from consumption of forage crops is actively transported during lactation by the sodium-iodide symporter present in the mammary gland. 17,26,30,[45][46][47] The adolescent and adult food models also show that consumption of vegetables and fruits were significant sources of perchlorate, which is consistent with earlier studies. 21,22,44 In addition, the contribution of dark-green leafy vegetables, which was significant in the adult food model, is well-supported by other studies.…”

“…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.…”

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

“…This contamination can arise from natural sources (Rajagopalan et al, 2006;Rao et al, 2007), diffuse releases from fertilizer use (Dasgupta et al, 2006;Rice et al, 2007), and localized contamination from explosives and fireworks (MDEP, 2006). Jackson et al (2004) found groundwater perchlorate concentrations greater than 0.5 mg/l in 46% of wells in west Texas and New Mexico.…”

“…Rajagopalan et al (2006), sampling in the same area, reported groundwater perchlorate concentrations between 0.1 mg/l and 4 mg/l in 35% of wells. Data from Massachusetts (MDEP, 2006) and Maryland (Rice et al, 2007), as well as infrequent detections in the UMCR1 data for many states at locations distant from known perchlorate releases, likewise suggest that low-level perchlorate contamination may be common, if not ubiquitous, in drinking water.…”

Determination of perchlorate in infant formula by isotope dilution ion chromatography/tandem mass spectrometry

“…Dairy products have been associated with human exposure to perchlorate (Rice et al 2007), and infants, in particular, can be exposed to perchlorate through bovine milk, human breast-milk (Gindberg et al 2007; Rice et al 2007), and infant formula (Schier et al 2010). Kirk et al (2003, 2005) reported the presence of perchlorate in all 47 dairy milk samples collected from 11 states and in 35 of 36 human milk samples collected from 18 states in United States.…”