Risk of Mortality From Esophageal Cancer Among US Poultry Workers, 1950-2019

Abstract

Background: While research suggests poultry industry workers have an increased risk of cancer mortality, little is known about their risk of esophageal cancer mortality. We investigated the association between working with poultry and esophageal cancer mortality while concurrently investigating other occupational and nonoccupational risk factors amongst poultry industry workers.

Methods: We conducted a case-cohort analysis from a cohort of unionized workers in the United States (N = 46,816) and conducted follow-up for mortality from 1950 to 2019 with the National Death Index. Cases were those who died of esophageal cancer and a sub-cohort was randomly selected (N = 2666) for further analysis. We interviewed participants and relatives about their work and personal life. We used multivariable Cox proportional hazards regression to estimate the hazard of esophageal cancer mortality due to working with poultry among the full cohort and weighted regression for the sub-cohort and those interviewed. We conducted exploratory analyses to estimate hazard ratios (HR) and 95% confidence intervals (CI) for each interview question, adjusted for confounders, and computed a false discovery rate (FDR).

Results: In the full and sub-cohort, working in a poultry plant was associated with an increased hazard of esophageal cancer mortality (HR = 1.62, 95% CI = 1.05, 2.50; and HR = 1.65, 95% CI = 1.03, 2.65, respectively). Among survey respondents, working in a poultry plant appeared to decrease the risk of esophageal cancer mortality (HR = 0.67; 95% CI = 0.34, 1.35).

Conclusions: Working in poultry plants may increase the risk of death from esophageal cancer, but further research is needed to validate these findings and explore potential mechanisms.

Keywords: esophageal cancer; food industry workers; lifestyle factors; occupational exposure; poultry; poultry slaughtering.

Figure 1

Study populations and data collection timeline. Black bar: All identified unionized members employed from January 1, 1950, to December 31, 1989 (full cohort). Dark gray bar: Follow‐up occurred from enrollment through death or December 31, 2019, to determine vital status. Light gray bar: *CATI‐Computer‐assisted telephone interviews. Wave 1 targeted all members in the sub‐cohort and cases identified as of 2010. Wave 2 targeted only cases. Sub‐cohort included those randomly selected from the full cohort. Cases included those who had died of esophageal cancer.

Figure 2

Study population flowchart. CATI, computer assisted interview; UFCW, United Food and Commercial Workers; Wave 1, 2010−2012, Wave 2, 2019−2021.

Figure 3

Directed acyclic graph (DAG) of the effect of poultry exposure on esophageal cancer mortality.

Figure 4

Hazard ratios and 95% confidence intervals for esophageal cancer mortality associated with working in the poultry industry. Model 1 is adjusted for age, gender, and race. Model 2 is adjusted for age, sex, race, tobacco use, alcohol intoxication, regular exercise, and weekly medication use.

Figure 5

p value plot for the obtained hazard associated with each interview question and esophageal cancer mortality. (A) Adjusted for age, sex, and race. (B) Adjusted for age, sex, race, tobacco use, alcohol intoxication, regular exercise, and weekly medication use.