Oil spill cleanup related exposures to benzene, toluene, ethylbenzene, xylenes, and n-hexane and incident diabetes mellitus.

BACKGROUND AND

OBJECTIVES

Exposure to benzene, toluene, ethylbenzene, xylenes, and n-hexane (BTEX-H) may contribute to the development of diabetes. Oil spill response and cleanup (OSRC) workers are exposed to BTEX-H but there are few relevant studies. We studied incident diabetes over 10 years of follow-up among OSRC workers.

METHODS

This analysis includes 21,726 participants (82.2 % male, mean age 39.9 years; 66.5 % White race) in the Gulf Long-term Follow-up Study - a prospective cohort of Deepwater Horizon (DWH) oil spill OSRC workers followed from 2011 to 2013 through 2021. Individual estimates of cumulative work-related exposures to specific BTEX-H chemicals and an aggregate sum (total BTEX-H) were derived from a job-exposure matrix that linked exposure group estimates derived from exposure measurements to self-reported DWH work histories. We used Cox models to estimate associations of quartiles of exposure to individual BTEX-H chemicals and total BTEX-H with diabetes incidence. We used quantile-based g-computation, quantifying associations with exposure to the BTEX-H chemicals, treating them as separate components in a mixture. We examined differences in associations by neighborhood disadvantage using the Area Deprivation Index (ADI) and by self-classified race in stratified analyses.

RESULTS

Exposure to the BTEX-H chemicals was associated with diabetes, with elevated hazard ratios for third and fourth quartiles of exposure compared to the first quartile. For example, total BTEX-H, Q3 and Q4 HRs were 1.10 95 %CI (0.91, 1.33) and 1.27 95 %CI (1.05, 1.53), respectively. The HR associated with a three-quartile increase in the BTEX-H mixture was 1.31 95 %CI (1.07, 1.59). Stratified analyses showed little variation by race and suggestions of variation by ADI.

CONCLUSION

Exposures to BTEX-H chemicals were associated with incident diabetes among OSRC workers for the individual BTEX-H chemicals, total BTEX-H, and the BTEX-H mixture. The range of exposures in this study make these findings relevant to other low to moderate exposure settings.