Perchlorate in Water Supplies: Sources, Exposures, and Health Effects

Abstract

Perchlorate exposure occurs from ingestion of natural or manmade perchlorate in food or water. Perchlorate is used in a variety of industrial products including missile fuel, fireworks, and fertilizers, and industrial contamination of drinking water supplies has occurred in a number of areas. Perchlorate blocks iodide uptake into the thyroid, and decreases the production of thyroid hormone, a critical hormone for metabolism, neurodevelopment, and other physiologic functions. Occupational and clinical dosing studies have not identified clear adverse effects, but may be limited by small sample sizes, short study durations, and the inclusion of mostly healthy adults. Expanding evidence suggests that young children, pregnant women, fetuses, and people co-exposed to similarly acting agents may be especially susceptible to perchlorate. Given the ubiquitous nature of perchlorate exposure, and the importance of thyroid hormone for brain development, studying the impact of perchlorate on human health could have far-reaching public health implications.

Incidence of Congenital Hypothyroidism Over 37 Years in Ireland

“…1 Similar increases have been observed in Western Australia (from 0.17 cases per 1000 births between 1981 and 1987 to 0.35 cases per 1000 births between 1988 and 1998) 2 and Italy (from 0.33 cases per 1000 births between 1987 and 1998 to 0.51 cases per 1000 births between 1999 and 2008). 10 Potential explanations for this observation include changes in population ethnic composition, 3 environmental changes (such as perchlorate exposure), 11 iodine deficiency, 12 and changes in clinical practice 13 and awareness that lead to better detection. Many screening programs' cutoff levels have changed over time, which may partially explain the increased case ascertainment rate.…”

“…Although changes in screening cutoffs and treatment practices over time are considered to be the main contributing factors to the previously described increasing incidence of CHT worldwide, other potential causes for the reported increase have been suggested. These include changes in population ethnic composition, 3 environmental changes, such as perchlorate exposure, 11 and iodine deficiency. 12 Unlike other European countries, Ireland does not have a salt iodization program and may consequently have a relatively high prevalence of iodine insufficiency.…”

Trends of perchlorate in Antarctic snow: Implications for atmospheric production and preservation in snow

“…Extensive human exposure to environmental perchlorate poses a significant health risk [Steinmaus, 2016]. Extensive human exposure to environmental perchlorate poses a significant health risk [Steinmaus, 2016].…”

“…Perchlorate (ClO 4 À ) has been found to be widespread in the environment. Extensive human exposure to environmental perchlorate poses a significant health risk [Steinmaus, 2016]. According to Jackson et al [2015], perchlorate is present in trace amounts on all continents, which strongly suggests that it is produced naturally.…”

Adverse Outcome Pathway on inhibition of Na+/I- symporter (NIS) leads to learning and memory impairment

“…There is strong evidence that decreased Thyroxine (T4) synthesis in the thyroid gland results in decreased T4 concentration in serum ( (Dong et al, 2017;Calil-Silveira et al, 2016;Tang et While T4 and T3 administration restored both serum and tissue levels of TH in gestating hypothyroid Infusion of dams with T4 after E18 did not prevent alterations of somatosensory cortex and hippocampus al., Liu et al, 2012;Pearce et al, 2012). Recovery experiments (cessation an exposure to NIS or TPO inhibitors) demonstrate recovery of serum T4 concentrations (Dong et al, 2017;Calil-Silveira et al, 2016;Tang et al, 2013;Liu et al, 2012;Pearce et al, 2012;Steinmaus, 2016aSteinmaus, , 2016b. T4 or T3 treatment during critical developmental windows, was shown to restore (or reduce) structural alterations in brain Auso et al, 2004;.…”