Brain and Central Nervous System Cancer and Benign Brain Tumors Among Chemical Plant Workers in Texas

Abstract

In the early 1980's, a clustering of brain and central nervous system cancers was observed among workers at a Texas City, Texas chemical plant. A series of studies with follow-up from 1941 to 1983 failed to identify an occupational cause. We added women and newly hired workers to these studies and expanded the follow-up from 1940 to 2001 using a retrospective cohort mortality design. The SMR for brain and central nervous system cancers was slightly less than ex- pected (SMR=0.93, 95% CI 0.60-1.38) whereas the SMR for benign brain tumors was slightly greater than expected (SMR=1.50, 95% CI 0.72-2.76) during the entire observation period. SMRs were close to expected levels when examin- ing sex, wage type, year of hire, years of latency, and duration of employment for these causes. We observed high rates of brain and central nervous system cancers from 1970 to 1984 but lower rates in the other periods. We conclude that the ex- cess cancer and tumor mortality reported in the earlier studies may be a random cluster and unrelated to workplace expo- sures.