Perchlorate in Indoor Dust and Human Urine in China: Contribution of Indoor Dust to Total Daily Intake

Perchlorate is used in fireworks and China is the largest fireworks producer and consumer in the world. Information regarding human exposure to perchlorate is scarce in China, and exposure via indoor dust ingestion (EDIindoor dust) has rarely been evaluated. In this study, perchlorate was found in indoor dust (detection rate: 100%, median: 47.4 mu g/g), human urine (99%, 26.2 ng/mL), drinking water (100%, 3.99 ng/mL), and dairy milk (100%, 12.3 ng/mL) collected from cities that have fireworks manufacturing areas (Yueyang and Nanchang) and in cities that do not have fireworks manufacturing industries (Tianjin, Shijiazhuang, Yuxi and Guilin) in China. In comparison with perchlorate levels reported for other countries, perchlorate levels in urine samples from fireworks sites and nonfireworks sites in China were higher. Median indoor dust perchlorate concentrations were positively correlated (r = 0.964, p < 0.001) with outdoor dust perchlorate levels reported previously. The total daily intake (EDItoal) of perchlorate, estimated based on urinary levels, ranged from 0.090 to 27.72 mu g/kg body weight (bw)/day for all studied participants; the percentage of donors who had EDItotal exceeding the reference dose (RfD) recommended by the United States Environmental Protection Agency (US EPA) was 79%, 48%, and 25% for toddlers (median: 1.829 mu g/kg bw/day), adults (0.669 mu g/kg bw/day), and children (median: 0.373 mu g/kg bw/day), respectively. Toddlers (0.258 mu g/kg bw/day) had the highest median EDIindoor dust, which was 2 to 5 times greater than the EDIindoor dust calculated for other age groups (the range of median values: 0.044 to 0.127 mu g/kg bw/day). Contribution of indoor dust to EDItotal was 26%, 28%, and 7% for toddlers, children, and adults, respectively. Indoor dust contributed higher percentage to EDItotal than that by dairy milk (0.55%).