The epidemiologist's responsibilities to research subjects in the occupational setting.

Workers require special consideration as subjects of epidemiology studies because of the direct connection of the results of studies to their personal health and livelihood. This article explores some of the issues regarding informed consent, and communications of study results. Surveillance data requires a long term commitment to employees to protect the commitment of initial informed consent statements. The consent process is viewed as an ongoing communication process between investigators and employees.

Assessment of colorectal cancer screening outcomes among workers involved in polypropylene manufacture.

To follow up on a previous finding of an elevated colorectal cancer incidence rate among Exxon employees on a unit devoted to the manufacture of polypropylene (the polyolefin unit [POU]), a company-sponsored screening program was offered to all former and present POU workers. Overall participation was 52.5%, with lower participation among older workers and workers who had retired or were no longer employed by the company. Evaluation of polyp prevalence rates for POU workers v rates for non-Exxon employees screened at the same clinic showed a general pattern of elevated rates for POU employees, especially for mechanical and process workers. This pattern was most marked for polyps at least 0.5 cm in diameter, but findings were less clear for adenomatous polyps. The effect of factors that might bias evaluation of colorectal polyp prevalence rates (eg, selection bias, observation bias, genetic susceptibility) is discussed, but none of these factors seemed a likely explanation for the findings observed in this study.

Reasons for participation and nonparticipation in a colorectal cancer screening program for a cohort of high risk polypropylene workers.

Little is known about reasons for participation in occupational colorectal cancer screening programs using flexible sigmoidoscopy and barium enema. To assess this issue, telephone interviews were conducted with a sample of participants and nonparticipants in such a program. This study was a follow-up of a previous assessment of factors that affected screening participation among a cohort found to have elevated rates of colorectal cancer. The major finding of this survey was that the absence of symptoms was the major reason for nonparticipation, although both participants and nonparticipants expressed the view that early detection was important and that colorectal cancer could be cured if treated at an early stage. Based on the results of this study and of other surveys, educational messages to workers explaining the asymptomatic development of colorectal cancer should be tried as a way of increasing participation.