Confirmation of the amount/duration leads to carcinogenesis by chronic arsenic exposure and the avoidable possibility of carcinogenesis by exposure mitigation

Research Project

Project/Area Number	17H04655
Research Category	Grant-in-Aid for Scientific Research (B)
Allocation Type	Single-year Grants
Section	海外学術
Research Field	Hygiene and public health
Research Institution	Asahikawa Medical College
Principal Investigator	Yoshida Takahiko 旭川医科大学, 医学部, 教授 (90200998)
Co-Investigator(Kenkyū-buntansha)	山内博聖マリアンナ医科大学, 医学部, 教授 (90081661)
Project Period (FY)	2017-04-01 – 2022-03-31
Project Status	Completed (Fiscal Year 2022)
Budget Amount *help	¥17,680,000 (Direct Cost: ¥13,600,000、Indirect Cost: ¥4,080,000) Fiscal Year 2021: ¥2,470,000 (Direct Cost: ¥1,900,000、Indirect Cost: ¥570,000) Fiscal Year 2020: ¥3,640,000 (Direct Cost: ¥2,800,000、Indirect Cost: ¥840,000) Fiscal Year 2019: ¥3,770,000 (Direct Cost: ¥2,900,000、Indirect Cost: ¥870,000) Fiscal Year 2018: ¥3,770,000 (Direct Cost: ¥2,900,000、Indirect Cost: ¥870,000) Fiscal Year 2017: ¥4,030,000 (Direct Cost: ¥3,100,000、Indirect Cost: ¥930,000)
Keywords	砒素 / 飲料水 / 慢性砒素中毒 / 皮膚悪性腫瘍 / ボーエン病 / 発癌 / 予防 / フィールド調査 / 中国内モンゴル自治区 / ヒ素 / 皮膚症状 / 皮膚癌 / 慢性曝露 / 曝露軽減 / 慢性ヒ素中毒 / 曝露 / 改善 / 砒素中毒 / 悪性腫瘍 / Bowen病 / 量反応関係 / 発癌閾値 / 慢性中毒 / 影響因子 / 発癌予測 / 慢性影響
Outline of Final Research Achievements	Since the 1980s, we have investigated the effects of reducing arsenic exposure among the residents in the chronic arsenic poisoning field caused by drinking groundwater contaminated with naturally occurring inorganic arsenic in the Inner Mongolia, China. Since the field survey was suspended from 2020 due to the COVID19 epidemic and could not be resumed by the end of research period, so we analyzed 5 Bowen's disease patients obtained by 2019. The cases with the history of arsenic exposure as at least 6 years and the total arsenic exposure was at least 1.31 year-ppm, the duration from the start of arsenic exposure to onset was 12-18 years in the shortest case and 25-31 years in the longest case. There was no significant numerical correlation between high-concentration exposure duration or total arsenic exposure and the onset of malignancy. Although urinary 8OHdG was decreased by exposure reduction, carcinogenesis was not suppressed.
Academic Significance and Societal Importance of the Research Achievements	本研究は新型コロナ感染症流行によりフィールド調査が継続出来ない困難に遭遇し、少数の皮膚悪性腫瘍症例での検討にとどまったが、砒素曝露歴、総砒素曝露量が一定程度超えると、砒素曝露開始から12-31年で皮膚癌発症に至る事、発症に性差が無い事、砒素曝露軽減によっても発癌抑制は見られないことが分かった。本研究の成果により、砒素曝露による皮膚癌の発症を予防するには、他の慢性砒素中毒症状が明確化する前に、飲料水の検査を行い砒素曝露そのものを避ける必要性が分かった。新しい飲料水の供用に先立って水質検査する重要性が再認識され、発展途上国等の住民の健康保持のため安全な水の確保の重要性を啓発すべきことがわかった。