Occupational exposure to organic solvents and risk of bladder cancer

BACKGROUND: Bladder cancer has been linked to several occupations that involve the use of solvents, including those used in the dry-cleaning industry. OBJECTIVES: We evaluated exposure to solvents and risk of bladder cancer in 1182 incident cases and 1408 controls from a population-based study. METHODS: Exposure to solvents was quantitatively assessed using a job-exposure matrix (CANJEM). Exposure to benzene, toluene and xylene often co-occur. Therefore, we created two additional sets of metrics for combined benzene, toluene and xylene (BTX) exposure: (1) CANJEM-based BTX metrics and (2) hybrid BTX metrics, integrating CANJEM with lifetime occupational histories and exposure-oriented modules capturing respondent-specific tasks and chemicals. Adjusted odds ratios (ORs) and 95% confidence intervals (95% CI) were estimated using logistic regression. RESULTS: Bladder cancer risks were increased among those ever exposed to benzene (OR = 1.63, 95% CI: 1.14–2.32), toluene (OR = 1.60, 95% CI: 1.06–2.43), and xylene (OR = 1.67, 95% CI: 1.13–2.48). A statistically significant exposure-response relationship for cumulative BTX exposure was observed, stronger using the hybrid BTX metrics (OR_Q1vsUnexposed = 1.26, 95% CI: 0.83–1.90; OR_Q2vsUnexposed = 1.52, 95% CI: 1.00–2.31; OR_Q3vsUnexposed = 1.88, 95% CI: 1.24–2.85; OR_Q4vsUnexposed = 2.23, 95% CI: 1.35–3.69) (p-trend = 0.001) than using CANJEM-based metrics (p-trend = 0.02). IMPACT: Evidence on specific organic solvents and bladder cancer remains limited. Increasing exposure to BTX as a group showed a significant exposure-response with bladder cancer. Further evaluation of BTX and other solvents, particularly concurrent exposures, is needed.

Shuai Xie, Melissa C. Friesen, Dalsu Baris, Molly Schwenn, Nathaniel Rothman, Alison Johnson, Margaret R. Karagas, Debra T. Silverman, Stella Koutros