Objectives To investigate the association between occupational exposure to aromatic hydrocarbon solvents and risk of multiple myeloma (MM) in a large, consortium-based study.
Methods We pooled data on 2854 cases and 10 743 controls from nine studies participating in the InterLymph consortium. Occupational exposures to benzene, toluene and xylene were assigned by a job–exposure matrix, coupled with ‘correction’ of exposure probability by self-reported or expert-assessed exposure from the individual studies. Cumulative intensity was calculated as the job-specific exposure intensity multiplied by job duration, summed across jobs. Associations were estimated using logistic regression, with inclusion of covariates for study matching factors and other potential confounders. We repeated our main analysis using random-effects meta-analysis to evaluate heterogeneity of effect.
Results Benzene, toluene and xylene were each associated with MM. For the three solvents, the highest quartile of high-probability cumulative intensity exposure (vs unexposed) was associated with 42% to 63% increased risks of MM. Associations with toluene and xylene exposures were fairly consistent and robust to sensitivity analyses. The estimated effect for benzene was moderately heterogeneous between the studies. Each solvent’s association with MM was stronger for exposure occurring within 20 years of diagnosis than with exposure lagged by more than 20 years.
Conclusions Our study adds important evidence for a role of aromatic hydrocarbon solvents in causation of MM. The difficulty in disentangling individual compounds in this group and a lack of data on potential carcinogenicity of toluene and xylene, in widespread current use, underscore a need for further epidemiological evaluation.
- public health
- retrospective exposure assessment
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Contributors AJDR, PC, JS, EBB and BMB conceived of and designed the study. AJDR, PC and LHS carried out the study protocol through data acquisition, data organisation and data analysis. All authors contributed to data interpretation, drafting the manuscript and revising the work for important intellectual content.
Funding This study was funded by the National Institute of Environmental Health Sciences (5R21ES021592).
Competing interests None declared.
Patient consent Not required.
Ethics approval Drexel University IRB.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement Data from this pooled study that comprised multiple case–control studies conducted by individual institutions may be shared only with permission of the individual institutions, which hold the original study data.