Elevated concentrations of bromate in Drinking water and groundwater from Kuwait and associated exposure and health risks.

Drinking water is an important source of human exposure to bromate, an ubiquitous environmental contaminant and a suspect human carcinogen. Nevertheless, little is known with regard to bromate exposure from water produced by thermal desalination of seawater. The purpose of this study was to determine the occurrence of bromate in desalinated drinking water and groundwater from Kuwait and estimate associated exposure and health risks to consumers. In this study, 194 tap and ground water samples collected from Kuwait were analyzed for the presence of bromate and bromide (reduced form of bromine). Bromate was found in almost all tap water samples with a mean concentration of 19.6 µg/L, which is higher than the maximum acceptable contaminant level (MCL) of 10 µg/L. The mean concentration of bromide in tap water samples was 46.2 µg/L. In bottled water, lower mean bromate concentration was found (2.89 µg/L) with mean bromide levels at 76.1 µg/L. Saline brackish water had bromate concentration at 9.48 µg/L while bromate was not detected in saline groundwater/well water samples. The mean estimated daily intake (EDI) of bromate by the Kuwaiti population through tap water and commonly consumed bottled water was 21.7 µg/d and 3.21 µg/d, respectively. Among the five age groups, 3 to 5-year-old children had the highest EDI of bromate at 15.4 µg/d. The excess cancer risk due to ingestion of bromate in tap water was estimated to be 3.92 × 10-4, which is approximately one order of magnitude higher than the maximum acceptable level of risk (2× 10-5). This study highlights the significance of desalinated water as a source of bromate exposure.

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 µg kg(-)(1) bw day(-)(1) (36.2%), followed by fruits at 0.026 µg kg(-)(1) bw day(-)(1) (15.3%) and non-leafy vegetables at 0.017 µg kg(-)(1) bw day(-)(1) (10.1%). The urinary perchlorate geometric mean (GM) concentrations ranged from 8.51 to 17.1 µg 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 µg 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 µg kg(-)(1) bw day(-)(1) for the five age groups, with a mean total daily intake of 0.17 µg kg(-)(1) bw day(-)(1) for the general population. The highest estimated dietary mean daily intake of perchlorate (0.67 µg 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).