The relationship between multiple myeloma and occupational exposure to six chlorinated solvents
Laura S Gold et al. 2011
Evidence from a relatively large case-control study (181 cases (71% response) vs. 481 controls (52% response)) suggests that exposures to certain chlorinated solvents may be associated with increased incidence of multiple myeloma; however, the study is limited by relatively low participation (52%) among controls
What this paper adds:
The aetiology of multiple myeloma is poorly understood.
- The purpose of this research was to examine relationships between occupational exposures to chlorinated solvents and multiple myeloma.
This research provides evidence that certain chlorinated solvents, most notably trichloroethylene, are associated with increased incidence of multiple myeloma.
While results were less clear, exposure to 1,1,1-trichloroethane, methylene chloride, perchloroethylene, carbon tetrachloride and chloroform also conferred increased risk of multiple myeloma in our population.
Objectives Few studies have examined whether exposure to chlorinated solvents is associated with multiple myeloma. We evaluated associations between multiple myeloma and occupational exposure to six chlorinated solvents: 1,1,1-trichloroethane, trichloroethylene (TCE), methylene chloride (DCM), perchloroethylene, carbon tetrachloride and chloroform.
Methods In-person interviews obtained occupational histories and information on jobs with likely solvent exposure. We assigned exposure metrics of probability, frequency, intensity and confidence using job-exposure matrices modified by job-specific questionnaire information. We used logistic regression to estimate ORs and 95% CIs for associations between multiple myeloma and ever exposure to each, and any, chlorinated solvent and analysed whether associations varied by duration and cumulative exposure. We also considered all occupations that were given the lowest confidence scores as unexposed and repeated all analyses.
Results Risk of multiple myeloma was elevated for subjects ever exposed to 1,1,1-trichloroethane (OR (95% CI): 1.8 (1.1 to 2.9)). Ever exposure to TCE or DCM also entailed elevated, but not statistically significant, risks of multiple myeloma; these became statistically significant when occupations with low confidence scores were considered unexposed (TCE: 1.7 (1.0 to 2.7); DCM: 2.0 (1.2 to 3.2)). Increasing cumulative exposure to perchloroethylene was also associated with increasing multiple myeloma risk. We observed non-significantly increased multiple myeloma risks with exposure to chloroform; however, few subjects were exposed.
Conclusions Evidence from this relatively large case-control study suggests that exposures to certain chlorinated solvents may be associated with increased incidence of multiple myeloma; however, the study is limited by relatively low participation (52%) among controls.