A Case-Cohort Study to Investigate the Excess of Liver Cancer Observed in Workers in Poultry Slaughtering & Processing Plants

Abstract

This is a case-cohort study to examine whether the excess of liver cancer deaths observed in workers in poultry plants could be explained by oncogenic viruses and chemical carcinogenic exposures within the plants. A detailed telephone questionnaire was administered, and responses were analyzed by logistic regression. Odds ratios for several indicators of high exposure to oncogenic viruses or chemical carcinogens in poultry plants and related industries were elevated, but not statistically significant, except the odds ratio for direct contact with the blood of meat in kitchens, eating places, etc. Established risk factors were replicated, and new ones identified.

The study was unable to unequivocally assess risks due to oncogenic viruses or chemical carcinogenic exposures in poultry plants, mainly because observed elevated risks did not achieve statistical significance. The same also applies to some non-occupational factors. Noteworthy risk factors identified include the increased risks for eating cabbage, mussels, blood sausage, meringue, playing football, and decreased risks for history of frequent intake of soft drinks, gelatin-based meals, vitamins, frequent use of microwave oven to cook, and history of childhood diseases, and nonspecific symptoms. The significance of these findings is unknown, and they will need to be replicated in studies with adequate statistical power.

Acknowledgments

Our sincere thanks go to United Food and Commercial Workers (UFCW) International Union and all the participating UFCW local unions for their exemplary and continuing support over the years, without which this study would not have been possible. We also thank participating state cancer registries all over the country that kindly provided histologic data. Our gratitude goes to all the subjects that granted an interview for the study and diligently provided the unprecedented detailed information requested in the questionnaire. A large part of the success of the study is in no small measure due to their generosity. Finally, we are indebted to our research assistants for their dedication and excellent performance, in collecting the valuable questionnaire information.

Disclosure Statement

No potential conflict of interest was reported by the authors.

Human Subjects Research

The protocol for this case-cohort study was approved by the Human Subjects Committee (Institutional Review Board) of the University of North Texas Health Science Center.

Additional information

Funding

The study was funded by a grant (R01 OH 009572) from the National Institute for Occupational Safety and Health, U.S.A.