PROPORTIONAL MORTALITY ANALYSIS OF WASTE-WATER TREATMENT SYSTEM WORKERS BY BIRTHPLACE WITH COMMENTS ON AMYOTROPHIC-LATERAL-SCLEROSIS

There is concern that wastewater treatment system workers are at risk for cancers and diseases affecting the neurological and digestive syst ems. However, these diseases have also been linked to early exposures. A proportional mortality study was conducted on a large cohort of was tewater treatment system workers who were divided into two groups, mig rants and nonmigrants, by place of birth as reported on their death ce rtificates. The migrant worker group was significantly higher than the US white male population for cancer of the stomach, leukemia, and all lymphopoietic cancers. Migrant workers also had an elevated ratio for all diseases of the nervous system and sense organs. No cases of amyo trophic lateral sclerosis were found The American-born workers had an elevated rate of death for arteriosclerotic heart disease compared wit h the US white male population. We suggest that place of birth may pre sent a confounding factor when evaluating exposures in employee groups .