Carcinogenic risk assessment of arsenic poisoning in Bangladesh and ingestion of organo-arsenic in Japan.

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The purpose of this study was to examine the association between current arsenic level of well water and urinary arsenic concentration to examine the effectiveness of Bangladeshi mitigation programs. A community-based cross-sectional study was conducted in the Pabna district of Bangladesh between May and July 2005. We included 174 married couples and collected their drinking water from 138 wells. Of 326 subjects, 304 cases exceeded urinary arsenic level of 40μg/1.5L/day. Of all wells, 23.1% wells had arsenic level >50 μg/L. Multiple-adjusted odds ratio of urinary arsenic level >40μg/1.5L/day were 8.90 (95% CI : 3.31-23.93) for arsenic level of well water of 11-50 μg/L and 53.07 (11.91-236.46) for that of 51.332 μg/L as compared with that of 【less than or equal】10 μg/L. These results suggest that arsenic level of well water of 11.50 μg/L that Bangladesh government regarded as safe were not safe.We performed speciation analysis of urinary arsenic for 210 Japanese male subjects without occupational exposure using HPLC-ICP-MS. The median values of urinary arsenics were as follows : sodium arsenite (AsIII),3.5 ; sodium arsenate (AsV), 0.1 ; monomethylarsonic acid (MMA), 3.1 ; dimethylarsinic acid (DMA), 42.6 ; arsenobetaine (AsBe), 61.3 ; arsenocholine, trimethylarsine oxide, and unidentified arsenics (others), 5.2 ; and total arsenic (total As), 141.3 μgAs/1. It appears that the high levels of DMA and AsBe observed in Japan may be due in part to seafood intake.To clarify the risks of Hijiki ingestion, a 42-year-old male volunteer ingested 825 μg of iAs compounds contained in eight servings of commercial Hijiki food, after refraining from eating seafood for 3 months. The total amounts of AsV, AsIII, MMA and DMA excreted in urine over 50 h were 11.2, 31.8, 40.9 and 104.0 μg, respectively. Long-term ingestion of Hijiki might thus have the potential to cause arsenic poisoning.