Occupational exposure to metalworking fluids and risk of breast cancer among female autoworkers.
BACKGROUND
Metalworking fluids (MWF) are used for lubrication during metal manufacturing. Previous studies have observed increased risks of several cancers among MWF-exposed workers. We hypothesized that MWF may be associated with risk of breast cancer because they can contain carcinogenic or endocrine-disrupting chemicals.


METHODS
We conducted a case-control study nested in a cohort of 4,680 female automobile workers employed for at least 3 years between 1/1/41 and 1/1/85, with follow-up through 1994. Cases were identified using the National Death Index (NDI), Michigan cancer registries, and company records. Detailed quantitative MWF exposure data were available for each subject, although data on known breast cancer risk factors were not.


RESULTS
Ninety-nine cases of breast cancer and 626 matched controls were identified. There was a weak positive association between lifetime cumulative exposure to soluble MWF and breast cancer risk, but no evidence of association with either straight or synthetic fluids. When exposure was divided into time-windows, the association was strongest for soluble MWF in the decade preceding diagnosis. Controlling for earlier exposures, there was an odds ratio of 1.18 (95% CI=1.02-1.35) per mg/m3-year of cumulative exposure to soluble MWF in this 10-year period.


CONCLUSIONS
This hypothesis-generating study provides some preliminary evidence for an association between exposure to soluble MWF and increased risk of breast cancer. Additional studies of MWF and breast cancer, with data on known breast cancer risk factors, are warranted.
Thompson
Deborah
D
Center for Family and Community Health, Massachusetts Department of Public Health, Boston, Massachusetts 02108, USA. Deborah.c.Thompson@state.ma.us
Kriebel
David
D
Quinn
Margaret M
MM
Wegman
David H
DH
Eisen
Ellen A
EA
D000328:Adult; D001943:Breast Neoplasms / Q000139:chemically induced*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D016015:Logistic Models; D008153:Lubrication; D008669:Metallurgy; D008875:Middle Aged; D009784:Occupational Diseases / Q000139:chemically induced*; D016273:Occupational Exposure / Q000009:adverse effects*; D016017:Odds Ratio; D013997:Time Factors