Occurrence of perchlorate in indoor dust from the United States and eleven other countries: implications for human exposure.

Perchlorate is a widespread environmental contaminant and potent thyroid hormone disrupting compound. Despite this, very little is known with regard to the occurrence of this compound in indoor dust and the exposure of humans to perchlorate through dust ingestion. In this study, 366 indoor dust samples were collected from 12 countries, the USA, Colombia, Greece, Romania, Japan, Korea, Pakistan, Kuwait, Saudi Arabia, India, Vietnam, and China, during 2010-2014. Dust samples were extracted by 1% (v/v) methylamine in water. Analyte separation was achieved by an ion exchange (AS-21) column and analysis was performed by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The overall concentrations of perchlorate in dust were in the range of 0.02-104μg/g (geometric mean: 0.41μg/g). The indoor dust samples from China contained the highest concentrations (geometric mean: 5.38μg/g). No remarkable differences in perchlorate concentrations in dust were found among various microenvironments (i.e., car, home, office, and laboratory). The estimated median daily intake (EDI) of perchlorate for toddlers through dust ingestion in the USA, Colombia, Greece, Romania, Japan, Korea, Pakistan, Kuwait, Saudi Arabia, India, Vietnam, and China was 1.89, 0.37, 1.71, 0.74, 4.90, 7.20, 0.60, 0.80, 1.55, 0.70, 2.15, and 21.3ng/kgbodyweight (bw)/day, respectively. Although high concentrations of perchlorate were measured in some dust samples, the contribution of dust to total perchlorate intake was <5% of the total perchlorate intake in humans. This is the first multinational survey on the occurrence of perchlorate in indoor dust.