The relationship between multiple myeloma and occupational exposure to six chlorinated solvents

Abstract

Objectives-Few studies have examined whether exposure to chlorinated solvents is associated with increased risk of multiple myeloma (MM). Using occupational exposure information, we evaluated associations between the risk of MM and exposure to six chlorinated solvents: 1,1,1-trichloroethane (TCA), trichloroethylene (TCE), methylene chloride (DCM), perchloroethylene (PCE), carbon tetrachloride, and chloroform.Methods-MM cases were identified through cancer registries and controls were identified in the general population. In-person interviews obtained lifetime occupational histories and additional information on jobs with likely solvent exposure. We reviewed each job and 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 odds ratios (ORs) and 95% confidence intervals (CIs) for associations between MM and having ever been exposed to each, and any, chlorinated solvent and also analyzed 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 MM was significantly elevated for subjects ever exposed to TCA (OR (95% CI): 1.8 (1.1-2.9)). Ever-exposure to TCE or DCM also entailed elevated, but not statistically significant, risks of MM; these became statistically significant when occupations that had low confidence scores were considered unexposed (TCE: 1.7 (1.0-2.7); DCM: 2.0 (1.2-3.2)). Increasing duration and cumulative exposure to TCE were associated with significantly increasing risk of MM when jobs given low confidence were considered unexposed. Increasing cumulative exposure to PCE was also associated with increasing MM risk. We observed non-significantly increased MM risks with exposure to chloroform; however, few subjects were exposed.Corresponding author: Laura Gold, 1100 Fairview Ave. N., PO Box 19024, Seattle, WA USA 98109, Phone: (206) Fax: (206) Conclusions-Evidence from this relatively large case-control study suggests that exposures to certain chlorinated solvents may be associated with increased incidence of MM; however, the study is limited by relatively low participation (52%) among controls.

Occupational trichloroethylene exposure and risk of lymphatic and haematopoietic cancers: a meta-analysis

“…The most recent review, evaluating findings from seven epidemiological studies, found no association between TCE exposure and MM risk 21. Similar null results were found in our MM review, now including results from six additional studies not previously evaluated 31 32 36 39 52 58. Our study also found similar results to those of two previous reviews that reported no association between TCE exposure and risk of leukaemia,10 21 but with the inclusion of findings from five additional cohorts 31 36 39 50 52.…”

Comparison of two expert-based assessments of diesel exhaust exposure in a case–control study: programmable decision rules versus expert review of individual jobs

“…The lack of agreement may reflect differences in how the confidence definitions were applied, despite using a common definition, or differences due to information found after the decision rules were developed. The confidence metric is potentially valuable in sensitivity analyses of exposure–response associations,31 32 although the probability metric has also been used for this purpose 15. Our finding that different exposure assessment approaches result in such different confidence metrics suggests that we may need to consider other approaches to more consistently capture uncertainty in exposure decisions.…”

Cancer Mortality Among Aircraft Manufacturing Workers

“…[15][16][17][18][19][20][21][22] Results suggestive of an association between TCE exposure and cancer have derived almost exclusively from recently conducted community-based casecontrol studies. [23][24][25] Employment histories in community studies are self-reported and are quite diverse and heterogeneous in terms of jobs, industry, and geographic location. Exposure assessments in such studies are based on expert opinion and job-exposure matrices, methods that have yet to be validated 24,26 ; this lack of validation raises serious questions about the validity and accuracy of findings from these studies, which are increasingly being used to identify and confirm purported occupational causes of cancer.…”

“…The association was observed in only one of the two study cities, and risk estimates were statistically significant only after a post hoc sensitivity analysis. In a community-based NHL and TCE exposure study, 24 which utilized the same exposure assessment approach and the controls from the multiple myeloma study, 23 increased RRs for NHL were reported among those with the highest levels of TCE exposure, but no dose-or duration-response relationships were observed. The authors, perhaps for the first time, have acknowledged that the occupational exposure assessment methodology used in communitybased case-control studies has never been validated.…”