Perchlorate, Nitrate, and Iodide Intake through Tap Water

Abstract

Perchlorate is ubiquitous in the environment, leading to human exposure and potential impact on thyroid function. Nitrate can also competitively inhibit iodide uptake at the sodium-iodide symporter and thus reduce thyroid hormone production. This study investigates the intake of perchlorate, nitrate, and iodide attributable to direct and indirect tap water consumption. The National Health and Nutrition Examination Survey collected tap water samples and consumption data from 3262 U.S. residents during the years 2005-2006. The median perchlorate, nitrate, and iodide levels measured in tap water were 1.16, 758, and 4.55 μg/L, respectively. Measured perchlorate levels were below the United States Environmental Protection Agency (U.S. EPA) drinking water equivalent level for perchlorate (24.5 μg/L). Significant correlations were found between iodide and nitrate levels (r = 0.17, p < 0.0001) and perchlorate and nitrate levels (r = 0.25, p < 0.0001). On the basis of 24 h recall, 47% of the study participants reported drinking tap water; 89% reported either direct or indirect consumption of tap water. For the adult population (age ≥ 20 yrs) the median tap water consumption rate was 11.6 mL/kg-day. Using individual tap water consumption data and body weight, we estimated the median perchlorate, nitrate, and iodide dose attributable to tap water as 9.11, 11300, and 43.3 ng/kg-day, respectively, for U.S. adults. This perchlorate exposure dose from tap water is relatively small compared to the total perchlorate exposure dose previously characterized for the U.S. adults (median 64 ng/kg-day) and the U.S. EPA reference dose (700 ng/kg-day).

Safe Drinking Water? Effect of Wastewater Inputs and Source Water Impairment and Implications for Water Reuse

“…Recent studies have found perchlorate in finished water, with median levels up to 1.2 μg/L [95]. Using individual tap water consumption data and body weight, the median perchlorate dose attributable to tap water was 9.1 ng/kg-day.…”

On the stability of perchlorate ions against reductive attacks in electrochemical systems and in the environment

“…One of the main health hazards is connected with the very fact that perchlorate interferes with iodide uptake in the thyroid gland [35,36]. In large doses, it has been linked to anemia and fetal brain damage [30,35].…”

Dietary Factors and the Risk of Thyroid Diseases: A Review

“…[36][37][38] Regarding thyroid function, nitrate can competitively inhibit iodide uptake, 39,40) which may cause a reduction in thyroid hormone production. 41) In an assessment of the Iowa Women's Health Study, high nitrate intake through drinking water consumption and private well use seemed to increase the risk of ovarian cancer in postmenopausal women. 38) Similarly, a study by Ward et al 26) found a significantly increased risk of both thyroid cancer and hypothyroidism in females with high dietary nitrate intake living in the same region, but no significant association was found for nitrate ingestion via drinking water.…”