For over the past 50 years, cohort mortality studies have been one of the main methods used in epidemiology for evaluating cancer risk in workers occupationally exposed to carcinogens in various industries. They have proven effective and reliable in detecting the carcinogenic effects of agents such as asbestos, benzene, aniline dyes, etc. in the workplace. These studies have also been the main sources of the epidemiologic evidence that these agents are carcinogenic in humans. They have led to regulatory actions that have resulted in the dramatic reduction of such harmful exposures in the workplace, hence succeeded in protecting workers' health. The workplace is much safer now than it was 30-50 years ago because of these studies. However, in spite of the fact that a large number of these studies have been conducted in various occupational and industrial groups, attention has not been paid to workers in chicken slaughtering/processing plants. These workers typically belong to the lowest socioeconomic stratum and are among the lowest paid individuals in industry, with wages around the minimum allowed by law. Apart from the cohorts assembled in this proposed study, to our knowledge this occupational group has not been evaluated for cancer occurrence in cohort studies, even though other studies of weaker designs have suggested they may be at increased risk of developing cancer occupationally. This omission is all the more poignant because these workers are exposed at work to certain viruses that are among the most potent cancer-causing agents known in animals. In this application we propose to study cancer risk in this group of workers. The study will not only investigate whether exposure to infections with these viruses present a cancer hazard to these workers (i.e. cancer as an occupationally-induced infectious disease), it will also provide critical evidence as to whether human exposure to the oncogenic viruses of chickens in general is associated with the development of cancer. Infectious diseases are one of the priority areas identified by the National Institute for Occupation Safety and Health in its Occupational Safety and Health Research program.

R01OH008071

2004-05-01

2008-04-30