Exposure of the US Population to Nitrate, Thiocyanate, Perchlorate, and Iodine Based on NHANES 2005-2014.

Perchlorate, thiocyanate, nitrate, and iodide all have the same action of iodide uptake inhibition. Urinary samples were available for the US population through the National Health and Nutrition Examination Survey (NHANES) database for these compounds and were evaluated for the 2005 through 2014 time period. We were interested in whether exposures to the US population had changed since the mid-2000s. Given that these exposures were largely naturally derived and exposure was from food, we hypothesized that the levels of nitrate, thiocyanate, and perchlorate remained relatively stable over this time period. Additionally, we evaluated mean perchlorate equivalent concentrations (PEC) of all three goitrogens together. There was a significant decrease in urinary perchlorate from 2005 to 2014 (p < 0.01). Thiocyanate and iodide also decreased significantly (p < 0.01), but not nitrate (p = 0.35). PEC decreased since 2005 with contribution from perchlorate at less than 1%, while nitrate increased in contribution.