The relationship between multiple myeloma and occupational exposure to six chlorinated solvents.
OBJECTIVE
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.
Gold
Laura S
LS
Program in Epidemiology, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA. goldl@u.washington.edu
Stewart
Patricia A
PA
Milliken
Kevin
K
Purdue
Mark
M
Severson
Richard
R
Seixas
Noah
N
Blair
Aaron
A
Hartge
Patricia
P
Davis
Scott
S
De Roos
Anneclaire J
AJ
D000328:Adult; D000368:Aged; D004812:Epidemiologic Methods; D005260:Female; D006801:Humans; D006843:Hydrocarbons, Chlorinated / Q000032:analysis / Q000633:toxicity*; D008297:Male; D008824:Michigan / Q000453:epidemiology; D008875:Middle Aged; D009101:Multiple Myeloma / Q000139:chemically induced* / Q000453:epidemiology; D009784:Occupational Diseases / Q000139:chemically induced* / Q000453:epidemiology; D016273:Occupational Exposure / Q000009:adverse effects* / Q000032:analysis; D012997:Solvents / Q000032:analysis / Q000633:toxicity*; D014241:Trichloroethylene / Q000032:analysis / Q000633:toxicity; D014861:Washington / Q000453:epidemiology
D006843:Hydrocarbons, Chlorinated; D012997:Solvents; D014241:Trichloroethylene