The contributions of water to total levels of chlorate and perchlorate intake were determined using food and water samples from a market basket study from 10 locations in Japan between 2008 and 2009. Foods were categorized into 13 groups and analyzed along with tap water. The average total chlorate intake was 333 (min. 193-max. 486) μg/day for samples cooked with tap water. The contribution of tap water to total chlorate intake was as high as 47%-58%, although total chlorate intake was less than 32% of the tolerable daily intake, 1500 μg/day for body weight of 50 kg. For perchlorate, daily intake from water was 0.7 (0.1-4.4) μg/day, which is not high compared to the average total intake of 14 (2.5-84) μg/day, while the reference dose (RfD) is 35 μg/day and the provisional maximum tolerable daily intake (PMTDI) is 500 μg/day for body weight of 50 kg. The highest intake of perchlorate was 84 μg/day, where concentrations in foods were high, but not in water. The contribution of water to total perchlorate intake ranged from 0.5% to 22%, while the ratio of highest daily intake to RfD was 240% and that to PMTDI was 17%. Eight baby formulas were also tested--total chlorate and perchlorate intakes were 147 (42-332) μg/day and 1.11 (0.05-4.5) μg/day, respectively, for an ingestion volume of 1 L/day if prepared with tap water.

The concentrations of chlorate and perchlorate were examined by ion chromatography-tandem mass spectrometry (IC-MS-MS) in 106 bottled beverages purchased or obtained mainly in the Tokyo area to estimate exposure to these chemicals attributable to bottled beverages. The bottled beverages were classified into 5 categories: water from the water supply (n = 5), natural water (n = 49), bottled water (n = 10), tea (n = 25), and soft drinks (n = 17). Chlorate was detected in 85 bottled beverages (highest concentration, 700 µg/l), including all of the samples of bottled water from the water supply at levels ranging from 25 to 120 µg/l. Perchlorate was detected above the minimum reporting limit (i.e., 0.05 µg/l) from 62 bottled beverages, with the highest concentration of 0.92 µg/l. As the average consumption of bottled beverages calculated from market statistics is approximately 400 ml/day per person, it seems important to take the amounts of chlorate and perchlorate ingested from bottled beverages into consideration for estimation of total intake of these chemicals.

Koji KosakaThe behaviour of pyrene and its decomposition by-products in chlorination and their aryl hydrocarbon receptor (AhR) ligand activities were investigated. In the study on pyrene behaviour in chlorination, the pyrene and chlorine concentrations and the pH range were 0.82-21 mg l 21 , 2.0-2.1 mg l 21 and 3.2-10, respectively. In the pH range of 3.2-5.1, pyrene was decomposed faster in the order of pH 3.2, 3.7 and 5.1. However, when the pH ranged from 5.1 to 10, pyrene was decomposed faster in a pH range of approximately 7.8-8.8. When the effects of the initial pyrene concentration were investigated, a lower pyrene concentration was decomposed faster. Pyrene decomposition in chlorination was inhibited by the presence of 30 mM ethanol, but was enhanced by the presence of 3.0 and 6.0 mgC l 21 humic acid.Pyrene decomposition by-products in chlorination were also characterized (pyrene, 92 mg l 21 ; chlorine, 7.9 mg l 21 ; pH, 7.1). 1-Chloropyrene, 1,6-and 1,8-dichloropyrenes, and pyrene-4,5-dione were identified as pyrene decomposition by-products. 1-Chloropyrene and pyrene-4,5-dione in chlorination were found to be major by-products at pH 3.2, but minor by-products at pH 7.1 (pyrene, 56-67 mg l 21 ; chlorine, 3.9-4.0 mg l 21 ). The yeast assay revealed that pyrene-4,5-dione was an AhR agonist.

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