Mustard gas exposure and mortality among retired workers at a poisonous gas factory in Japan: a 57-year follow-up cohort study

• Published in: Occupational and environmental medicine (London, England) Vol. 74; no. 5; pp. 321 - 327
• Main Authors: Mukaida, Kenichi, Hattori, Noboru, Iwamoto, Hiroshi, Onari, Yojiro, Nishimura, Yoshifumi, Kondoh, Keiichi, Akita, Tomoyuki, Tanaka, Junko, Kohno, Nobuoki
• Format: Journal Article
• Language: English
• Published: England BMJ Publishing Group Ltd 01.05.2017; BMJ Publishing Group LTD
• Subjects: Biological & chemical weapons; Bronchitis; Bronchitis, Chronic - chemically induced; Bronchitis, Chronic - mortality; Cancer; Carcinogens; Cause of Death; Chemical Warfare Agents - adverse effects; Cohort Studies; Death; Death Certificates; Emphysema; Emphysema - chemically induced; Emphysema - mortality; Exposure; Factories; Female; Females; Follow-Up Studies; Gases; Hospitals; Humans; Industrial plants; Industry; Japan - epidemiology; Lung cancer; Male; Males; Medical records; Mortality; Mustard gas; Mustard Gas - adverse effects; Neoplasms - chemically induced; Neoplasms - mortality; Occupational Diseases - chemically induced; Occupational Diseases - mortality; Occupational Exposure - adverse effects; Proportional Hazards Models; Respiratory diseases; Respiratory tract; Retirement; Workers; Workplace; World War I; Japan; INW, Japan, Honshu, Hiroshima Prefect; INW, Japan
• ISSN: 1351-0711; 1470-7926
• DOI: 10.1136/oemed-2015-103437

ObjectivesMustard gas (MG) has been the most widely used chemical warfare agent in the past century. However, few but conflicting data exist on the effects of MG exposure on long-term mortality. We investigated MG-related mortality in retired workers at a poisonous gas factory.MethodsWe assessed mortality rates among 2392 male and 1226 female workers, whose vital status could be determined through 31 December 2009, at a poisonous gas factory operating from 1929 to 1945 in Okuno-jima, Japan. The analysis employed standardised mortality ratios (SMRs) calculated using national and prefectural references and a Cox proportional hazard regression model. Applying the Kaplan-Meier method, we compared cumulative death rates in the study cohort stratified by an ‘Okuno-jima MG Index’ which represented the product of HRs derived for job category and length of service.ResultsAmong male workers, we found significant excesses in mortality from upper respiratory tract cancer (SMR 3.06), liver cancer (1.67), lung cancer (2.01) and chronic bronchitis/emphysema (4.84) compared with the national population, as well as stomach cancer (1.20) versus the Hiroshima Prefecture population. When stratified into 3 subgroups by the Okuno-jima MG Index, those with a higher Okuno-jima MG Index had significantly higher cumulative rates of death from respiratory cancer and chronic bronchitis/emphysema.ConclusionsMG exposure significantly increases the long-term risk of death from respiratory cancer and chronic bronchitis/emphysema. The Okuno-jima MG Index may be a useful indicator for estimating cumulative MG exposure.