Widespread occurrence of perchlorate in water, foodstuffs and human urine collected from Kuwait and its contribution to human exposure

Perchlorate is a thyroid hormone-disrupting compound and is reported to occur widely in the environment. Little is known on human exposure to perchlorate in Kuwait. In this study, 218 water samples, 618 commonly consumed foodstuffs and 532 urine samples collected from Kuwait were analysed to assess the exposure of the Kuwaiti population to perchlorate. For the estimation of daily intake of perchlorate, food consumption rates were obtained from the National Nutrition Survey in the State of Kuwait (NNSSK). The results showed that leafy vegetables accounted for a major share of perchlorate exposure among the Kuwaiti population at 0.062 mu g kg(-1) bw day(-1) (36.2%), followed by fruits at 0.026 mu g kg(-1) bw day(-1) (15.3%) and non-leafy vegetables at 0.017 mu g kg(-1) bw day(-1) (10.1%). The urinary perchlorate geometric mean (GM) concentrations ranged from 8.51 to 17.1 mu g l(-1) for the five age groups, which were higher than those reported in other countries. The estimated urinary perchlorate exposure for the Kuwaiti general population was 0.42 mu g kg(-1) bw day(-1), which was higher than that reported for the United States. The dietary intake of perchlorate for the Kuwaiti population ranged from 0.14 to 0.67 mu g kg(-1) bw day(-1) for the five age groups, with a mean total daily intake of 0.17 mu g kg(-1) (b)w day(-1) (f)or the general population. The highest estimated dietary mean daily intake of perchlorate (0.67 mu g kg(-1) bw day- 1) was found for children at 3-5 years. The estimated dietary perchlorate exposure in Kuwait is higher than the recommended mean reference dose (RfD) but lower than that of provisional maximum tolerable daily intake (PMTDI) set by the Joint FAO/WHO Expert Committee on Food Additives (JECFA).