Background: Cadmium, a ubiquitous environmental pollutant, is classified as a carcinogenic substance. Several laboratory and epidemiologic studies of workers and subjects in polluted areas have suggested a positive association between cadmium exposure and risk of several cancers. However, data from general populations are sparse. We prospectively examined the association between cadmium exposure and incidence of cancer in a Japanese population with a relatively high dietary intake of cadmium.
Methods: We conducted a population-based prospective study in 90,383 Japanese men and women 45–74 years of age. Participants responded to a validated questionnaire that included 138 food items. We estimated dietary cadmium intake from 6 food groups, based on the questionnaire data. During 9 years of follow-up, 5849 cancer cases were identified. Hazard ratios (HRs) and 95% confidence intervals (CIs) for cancer were calculated by Cox proportional hazards modeling.
Results: There was no evidence of an association of cadmium consumption and total cancer, with HRs in the highest versus lowest cadmium intake group of 0.94 (95% CI = 0.82 to 1.08; test for trend, P = 0.46) for men and 0.96 (0.81 to 1.15; 0.60) for women. No site-specific cancers were associated with cadmium intake in men or women.
Conclusion: We found no associations of cancer with cadmium, at least at the exposure levels observed in a general population in Japan.
From the aEpidemiology and Prevention Division, Research Center for Cancer Prevention and Screening, National Cancer Center, Tokyo, Japan; and bResearch Center for Occupational Poisoning, Kansai Rosai Hospital, Japan Labour Health and Welfare Organization, Hyogo, Japan.
Submitted 25 July 2011; accepted 4 November 2011; posted online 13 March 2012.
Supported by Management Expenses Grants from the Government to the National Cancer Center, Grants-in-Aid for Cancer Research, for the 3rd Term Comprehensive 10-year Strategy for Cancer Control, for Research on Risk of Chemical Substances from the Ministry of Health, Labour and Welfare of Japan, and for Young Scientists (B) from the Ministry of Education, Culture, Sports, Science and Technology. The authors reported no other financial interests related to this research.
Correspondence: Norie Sawada, Epidemiology and Prevention Division, Research Center for Cancer Prevention and Screening, National Cancer Center, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045, Japan. E-mail: firstname.lastname@example.org.