Student Research: Jonathan Hofmann
The nematocide 1,2-dibromo-3-chloropropane (DBCP) was widely used in the United States and abroad during the late 1960's and 1970's. Today DBCP is known to cause sterility in mean and is classified as a possible carcinogen by the International Agency for Research on Cancer. Previous epidemiologic studies have been limited in their ability to detect associations between DBCP exposure and mortality outcomes.
In this retrospective cohort study, we characterized the mortality experience of a previously studied cohort of Costa Rican banana plantation workers that has been expanded and update. The cohort include 40,959 individuals who worked on banana plantations between 1972 and 1979. Work records were linked with the Costa Rican Mortality Registry to determine outcomes through 1999. Observed deaths in the cohort were compared to expected deaths based on national mortality rates in Costa Rica. Standardized Mortality Ratios (SMRs) were calculated for all causes of death combined, and also for the specific causes of death that may be associated with employment on banana plantations and exposure to DBCP.
We observed an all-causes SMR of 0.77 for men (95% CI 0.75-0.80) and 0.90 for women (95% CI 0.80-1.02). The risk of death from injurious events (e.g. accidents, suicide, and homicide) was greater than expected for both men (SMR=1.15; 95% CI 1.08-1.23) and women (SMR=2.11; 95% CI 1.54-2.82). Significantly elevated mortality rates from septicemia were also observed among men (SMR=2.96; 95% CI 1.90-4.40) and women (SMR=7.00; 95% CI 2.57-15.23). Non-significant increases in mortality were observed for testicular cancer, penile cancer, and Hodgkin's disease in mean, and for cervical cancer and lung cancer in women. Incomplete reporting of deaths in the Mortality registry and the lack of precise exposure data have limited our ability to detect associations between exposure to DBCP and mortality outcomes.