Unusual sex ratio of births to carbon setter fathers.

In the years of 1980-1990, there were 139 birth records filed in Washington State on which father's occupation was designated as "carbon setter," a job title specific to aluminum reduction plants of the prebake type. Fifty-three (53) of these records specified sex of the birth as male, while 86 records specified sex of the infant as female. This gives a sex ratio of 0.381, which is a significant departure from the usual sex ratio at birth (proportion male = 0.512). Surveillance of sex ratio by paternal occupation is a simple method of monitoring for genotoxicity.