Mortality in workers in poultry slaughtering/processing plants: the Missouri poultry cohort study.

BACKGROUND: Subjects who work in poultry slaughtering and processing plants have one of the highest human exposures to viruses that cause cancer in chickens and turkeys. It is not known whether these viruses cause cancer in humans also. Epidemiological studies investigating this issue are scarce. AIMS AND METHODS: Mortality was studied during the period 1969-90 in a cohort of 7700 subjects who worked in poultry slaughtering and processing plants and were members of a local poultry union in the State of Missouri. RESULTS AND CONCLUSIONS: Statistically significant excess risks of non-malignant respiratory diseases, accidents, and symptoms, senility, and ill-defined conditions, and increased but not statistically significant excesses for some cancers were observed in particular race/sex groups. Most of these results were based on small numbers of deaths, and in many cases were evident only in particular subgroups of the cohort. Because of this and the multiple comparisons made, chance could not be ruled out in explaining the findings. Furthermore, the cohort is young, with only 6% deceased at the end of follow up. Further follow up of this cohort is required before a reliable assessment of the potential risk associated with these viruses can be made.

On the need to assess cancer risk in populations environmentally and occupationally exposed to virus and chemical agents in developing countries.

Evidence exists that exposure to poultry oncogenic viruses may produce elevated cancer mortality in human populations, particularly excesses of cancer of lung and excesses of cancer of lymphopoietic tissues. To date, this potential risk is unknown in populations from the developing countries. This paper suggests the need to assess cancer risk in populations of developing countries with reported environmental exposure to chicken meat products and eggs; the need to assess risk of cancer in populations inoculated with vaccines from infected chicken embryos; and the need to assess risk of cancer in occupational populations highly exposed to poultry oncogenic viruses, and with potential concurrent exposure to chemical agents known or suspected to be carcinogens.