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A case-control study of occupational exposure to metalworking fluids and bladder cancer risk among men
  1. Joanne S Colt1,
  2. Melissa C Friesen1,
  3. Patricia A Stewart1,2,
  4. Park Donguk3,
  5. Alison Johnson4,
  6. Molly Schwenn5,
  7. Margaret R Karagas6,
  8. Karla Armenti7,
  9. Richard Waddell6,
  10. Castine Verrill5,
  11. Mary H Ward1,
  12. Laura E Beane Freeman1,
  13. Lee E Moore1,
  14. Stella Koutros1,
  15. Dalsu Baris1,
  16. Debra T Silverman1
  1. 1Department of Health and Human Services, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
  2. 2Stewart Exposure Assessments, LLC, Arlington, Virginia, USA
  3. 3Korea National Open University, Seoul, Korea
  4. 4Vermont Cancer Registry, Burlington, Vermont, USA
  5. 5Maine Cancer Registry, Augusta, Maine, USA
  6. 6Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
  7. 7New Hampshire Department of Health and Human Services, Concord, New Hampshire, USA
  1. Correspondence to Joanne S Colt, Occupational and Environmental Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, 9609 Medical Center Drive, Room 6E140, Bethesda, MD 20892, USA; coltj{at}


Objectives Metalworking has been associated with an excess risk of bladder cancer in over 20 studies. Metalworking fluids (MWFs) are suspected as the responsible exposure, but epidemiological data are limited. We investigated this association among men in the New England Bladder Cancer Study using state-of-the-art, quantitative exposure assessment methods.

Methods Cases (n=895) and population controls (n=1031) provided occupational histories during personal interviews. For selected jobs, exposure-oriented modules were administered to collect information on use of three MWF types: (1) straight (mineral oil, additives), (2) soluble (mineral oil, water, additives) and (3) synthetic (water, organics, additives) or semisynthetic (hybrid of soluble and synthetic). We computed ORs and 95% CIs relating bladder cancer risk to a variety of exposure metrics, adjusting for smoking and other factors. Non-metalworkers who had held jobs with possible exposure to mineral oil were analysed separately.

Results Bladder cancer risk was elevated among men who reported using straight MWFs (OR=1.7, 95% CI 1.1 to 2.8); risk increased monotonically with increasing cumulative exposure (p=0.041). Use of soluble MWFs was associated with a 50% increased risk (95% CI 0.96 to 2.5). ORs were non-significantly elevated for synthetic/semisynthetic MWFs based on a small number of exposed men. Non-metalworkers holding jobs with possible exposure to mineral oil had a 40% increased risk (95% CI 1.1 to 1.8).

Conclusions Exposure to straight MWFs was associated with a significantly increased bladder cancer risk, as was employment in non-metalworking jobs with possible exposure to mineral oil. These findings strengthen prior evidence for mineral oil as a bladder carcinogen.

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