Occupation and bladder cancer risk in a population-based case-control study in New Hampshire

Objective: To identify occupations with excess bladder cancer risk in New Hampshire, where bladder cancer mortality rates have been elevated for decades. Methods: Lifetime occupational histories were obtained from interviews with 424 cases and 645 controls in a population-based case-control study. Unconditional logistic regression models were used to estimate odds ratios (ORs) and 95% confidence intervals (CI) for each occupation, adjusted for age and smoking. Analyses by duration of employment were carried out and interactions with smoking were examined. Results: Male tractor-trailer truck drivers had an elevated risk for bladder cancer ( OR = 2.4, CI = 1.4 - 4.1), with a significant positive trend in risk with increasing duration of employment (P-trend = 0.0003). Male metal/plastic processing machine operators also had a significant excess ( OR = 4.9, CI = 1.6 - 15.1), attributable mainly to molding/casting machine operators ( OR = 16.6, CI = 2.1 - 131). Elevated risk was also observed for male fabricators, assemblers, and hand workers ( OR = 1.8, CI = 1.0 - 3.4). Women in certain sales occupations ( sales clerks, counter clerks, and cashiers) had a significant excess risk ( OR = 2.2, CI = 1.3 - 3.9) and a significant trend with duration of employment (P-trend = 0.016), as did female health service workers (OR = 4.1, CI = 1.6 - 10.7; P-trend = 0.014). There was a positive interaction between smoking and employment as a health service worker ( p = 0.036). Conclusions: These findings are generally consistent with previous studies. Elevated risks for male molding/casting machine operators, female salesworkers, and female health service workers, especially those with a history of smoking, require further investigation.