To follow up earlier findings of increased colorectal cancer and polyp risk among a group of Texas polypropylene manufacturing workers, a second company-sponsored colorectal cancer screening program was conducted. Ninety-four (64%) of the 147 male workers negative for polyps in the first screening were rescreened. Age- and examiner-adjusted incidence rate ratios (IRRs) were modestly elevated for polypropylene manufacturing workers compared with patients screened at the same clinic for total (IRR = 1.31; 90% confidence interval [CI] = 0.84 to 2.03) and adenomatous (IRR = 1.80; 90% CI = 0.68 to 4.78) polyps. However, risk of adenomas among the highest exposed group (early term process/mechanical workers: IRR = 1.77; 90% CI = 0.51 to 6.18) was similar to risk in the least-exposed group (engineer/chemist/administrative workers: IRR = 2.02; 90% CI = 0.56 to 7.31). The modest, nonsignificant excesses and the similarity in risk across job categories does not suggest an occupationally related risk, although small numbers and potential biases preclude making definitive conclusions.
(C)1994 The American College of Occupational and Environmental Medicine