A multicenter cohort study in workers exposed to indium compounds: 16-year follow-up

2022 Fiscal Year Final Research Report

• Project/Area Number: 19H03906
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 58030:Hygiene and public health-related: excluding laboratory approach
• Research Institution: Keio University
• Principal Investigator: NAKANO Makiko 慶應義塾大学, 医学部(信濃町), 講師 (70384906)
• Co-Investigator(Kenkyū-buntansha): 田中 昭代 九州大学, 医学研究院, 講師 (10136484)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: インジウム / コホート研究 / 肺がん / 腎がん / KL-6 / 間質性肺炎

Outline of Final Research Achievements

Indium lung diseases of interstitial pneumonia and emphysema in the indium-exposed workers are new occupational lung disease established in Japan in 2007. This study started in 2003 and conducted a follow-up survey of 305 cohort members to observe chronic effects on the lungs. As a result, two workers with cancer (one lung cancer, two renal cancers) were confirmed by chest HRCT. The worker with lung cancer was diagnosed of a renal cancer on subsequent examination. On the other hands, of the other worker diagnosed of renal cancer, In-S had been at the lower limit of quantification (In-S <0.1 μg/L), and the level of indium in surgically resected kidney was also at the lower limit of quantification (<1 ng/g). Based on these findings, this case is unrelated to indium exposure. The possibility of indium-related cancer is unclear. Further follow-up is necessary.

Free Research Field

衛生学、産業疫学

Academic Significance and Societal Importance of the Research Achievements

2021年の特殊健康診断実施状況から、インジウム曝露者は国内に10943名いる（労働衛生のしおり 令和3年度）。海外では、2017年、国際がん研究機関（IARC）は、インジウム・スズ酸化化合物（ITO）をGroup 2B（ヒトに発がん性を有する可能性がある）とし、2018年に米国産業衛生専門官会議（ACGIH）は、ITOの作業環境濃度をこれまでの0.1mg/m3から0.1ng/m3とし曝露の低減を提案している。本研究成果は今後の衛生管理対策に有用で社会的意義がある。インジウムおよびインジウム化合物の人における発がん性の確認は、労働者の健康管理に寄与する点に創造性がある。