Manufacturing Industry Cancer Risk in Japan: A Multicenter Hospital-Based Case Control Study

Background It is well known that specific occupations can cause harm in developing malignant neoplasms. Chemical exposure is particularly high in the manufacturing industry and workers in this sector may face a higher occupational risk for cancer. We aimed to estimate inequalities in the risk of cancers related to occupational chemical exposure in various manufacturing categories. Methods Using nationwide clinical inpatient data (1984-2017) in Japan, we undertook a multicenter, case-control study with regard to risks of developing cancers among various manufacturing industry categories. Using the food manufacturing industry as the reference group, odds ratios and 95% confidence intervals for each industry were estimated by conditional logistic regression, adjusted for sex, age, admission period, and the admitting hospital. Medical record summaries accounting for 89% of industrial categories with high odds ratios were collected to confirm diagnoses made on the basis of histology. We estimated industrial hazards based on the Pollutant Release and Transfer Register. Results A reduced risk for some of common cancers was observed among lumber and wood products industries. Leather tanning, leather products and fur tended to show a higher risk: 2.36 (95% CI 1.15-4.83) for pancreatic cancer, 2.85 (95% CI 1.26-6.47) for liver cancer and 2.00 (95% CI 1.01-3.99) for lung cancer. For the electronics category, observations of high risk ranged from 2.09 (95%CI 1.18-3.70) for ureter cancer, to 2.49 (95% CI 1.79-3.55) for kidney cancer. Conclusions This study revealed industry risk inequalities in manufacturing categories were present with regard to the risk of common cancers in Japan.