Exposure to perchlorate via drinking water from eight major water basins in China and its health risks across different age groups.

Perchlorate is widely used in various industrial fields and has been widely detected in aquatic environments because of its high solubility and stability. Considering the endocrine-disrupting properties of perchlorate, the possibility of perchlorate exposure to humans through drinking water has become a public health concern. To examine whether perchlorate pollution in source water causes a risk to populations of different age groups exposed to residues in drinking water, the spatial distribution of perchlorate levels in source water and drinking water from eight major water basins in China in 2019 was quantified with ion chromatography. The average daily potential dose (ADD) of perchlorate from drinking water intake was estimated for different age groups in the Chinese population. The health risks were quantified by dividing the ADD by the reference dose corresponding to 50% inhibition of iodide uptake. The results revealed that source water contamination was the main factor in population exposure to perchlorate via drinking water. A significant difference in perchlorate contamination was observed, ranging from 5.03 µg/L to 1.80 mg/L, and high perchlorate contamination levels were detected in industrial areas with a high concentration of firework production. In contrast to previously inferred possible sources of perchlorate, i.e., emissions from the production of rockets and missiles, firework production was identified as the dominant source of perchlorate exposure via drinking water in this study. This investigation was conducted five years ago; however, the identification of sampling locations with a health risk quotient above 1 provides quantitative evidence that exposure to perchlorate in drinking water poses a risk to residents in areas affected by source pollution, and the results are helpful for identifying priority risk control areas.