SELENIUM IN FORAGE CROPS AND CANCER MORTALITY IN UNITED-STATES COUNTIES

The potential protective effect of selenium status on the risk of developing cancer has been examined in animal and epidermiologic studies. This ecological study investigated the association between U.S. county forage selenium status and site- and sex-specific county cancer mortality rates (1950-1969) using weighted least squares regression. Consistent, significant (p < .01) inverse associations were observed for cancers of the lung, rectum, bladder, esophagus, and cervix in a model limited to rural counties and for cancers of the lung, breast, rectum, bladder, esophagus, and corpus uteri in a model of all counties. No consistent significant positive associations were observed in the rural county models. This remarkable degree of consistency for the inverse associations strengths the likelihood of a causal relationship between low selenium status and an increased risk of cancer mortality.