NESTED CASE-CONTROL STUDY OF TUMORS OF THE HEMATOPOIETIC AND LYMPHATIC SYSTEMS AMONG WORKERS IN THE MEAT INDUSTRY

Workers in the meat industry are exposed to viruses that cause leukemi a and lymphoma in cattle and chickens, and also to carcinogenic chemic al agents. This case-control study, nested in a cohort of members of a meatcutters' union in Baltimore, Maryland, investigated whether occup ational exposures are associated with death from tumors of the hemopoi etic and lymphatic systems. Cases of these tumors represent all deaths which occurred in the cohort between 1949 and 1980. Excess risks of t umors of the hemopoietic and lymphatic systems were observed throughou t the meat industry, except in meatpacking plants. Slaughtering activi ties involving heavy exposure to oncogenic viruses were strongly assoc iated with these tumors, especially with lymphomas. Thus, elevated ris ks were observed for butchers who killed animals (odds ratio (OR) = 5. 3, 95% confidence interval (CI) 1.0-27.0); workers in chicken-slaughte ring plants (OR = 3.3, 95% CI 0.8-13.1); and workers in cattle/sheep/p ig abattoirs (OR = 2.8, 95% CI 0.8-9.5). Among supermarket workers, wr apping meat (mainly a female activity) was associated with increased r isk of tumors of the hemopoietic and lymphatic systems (OR = 3.8, 95% CI 1.0-14.3), with the odds of both lymphomas and tumors of the myeloi d stem cell being elevated. On the other hand, meatcutting in supermar kets (almost exclusively a male activity) was associated with multiple myeloma; the odds ratio for men was 18.0 (95% CI 1.6-207.51, with no myeloma cases being recorded in women. These associations persisted af ter limited control for exposures outside the industry that have also been observed to be associated with excess risk, such as exposure to p esticides, working/living on pig farms, and exposure to X-rays. The fi ndings provide evidence that workers in the meat industry may be at el evated risk of tumors of the hemopoietic and lymphatic systems. Furthe r studies with larger sample sizes are needed to identify more conclus ively which exposures play an etiologic role in the occurrence of the different histologic types of these tumors.