Antioxidants and cancer. Part VI. Selenium and age-adjusted human cancer mortality.

The possible epidemiologic relationship between selenium occurrence and cancer mortality was studied in cities and states located in areas with different levels of selenium bioavailability. Statistically significant differences were found in age-specific cancer death rates among states with high, medium, and low selenium levels. The death rates for specific types of cancer showed a larger difference in males than in females in the states with high selenium levels. The greater difference between males and females may be related to sex difference or to the fact that males are heavier smokers and are aslo more likely to be exposed to industrial pollution. In the states with high selenium levels, there was significantly lower mortality in both males and females from several types of cancer, particularly the environmental problem indicators, such as gastrointestinal and urogenital types of cancer.