A biological approach to characterizing exposure to metalworking fluids and risk of prostate cancer (United States).
OBJECTIVE
Prostate cancer is hormone-related and chemicals that interfere with hormones may contribute to carcinogenesis. In a cohort of autoworkers we characterized exposure to metalworking fluids (MWF) into age windows with homogenous biological risk for prostate cancer, and examined exposure-response relationships using semi-parametric modeling.


METHODS
Incident cases (n=872) were identified via Michigan cancer registry from 1985 through 2000. Controls were selected using incidence-density sampling, 5:1 ratio. Using a hormonal-based model, exposure was accumulated in three windows: (1) late puberty, (2) adulthood, and (3) middle age. We used penalized splines to model risk as a smooth function of exposure, and controlled for race and calendar year of diagnosis in a Cox model.


RESULTS
Risk of prostate cancer linearly increased with exposure to straight MWF in the first window, with a relative risk of 2.4 per 10 mg/m(3)-years. Autoworkers exposed to MWF at a young age also had an increased risk associated with MWF exposure incurred later in life. For soluble MWF there was a slightly increased risk in the third window.


CONCLUSIONS
Exposure characterization based on a hormonal model identified heightened risk with early age of exposure to straight MWF. Results also support a long latency period for exposure related prostate cancer.
Agalliu
Ilir
I
Department of Work Environment, University of Massachusetts, Lowell, MA, USA.
Eisen
Ellen A
EA
Kriebel
David
D
Quinn
Margaret M
MM
Wegman
David H
DH
D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D001336:Automobiles; D016022:Case-Control Studies; D016001:Confidence Intervals; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D007219:Industrial Oils / Q000009:adverse effects*; D016015:Logistic Models; D008297:Male; D008669:Metallurgy; D008875:Middle Aged; D009784:Occupational Diseases / Q000453:epidemiology / Q000209:etiology*; D016273:Occupational Exposure / Q000009:adverse effects*; D016016:Proportional Hazards Models; D011471:Prostatic Neoplasms / Q000453:epidemiology* / Q000209:etiology* / Q000473:pathology; D012016:Reference Values; D012042:Registries; D012189:Retrospective Studies; D012307:Risk Factors; D013997:Time Factors