A study published this week has investigated the relationship between occupational exposure to metalworking fluids (MWFs) in the steel industry and bladder cancer incidence[i].
The participants in the study were 84 bladder cancer patients and 251 controls, who were all interviewed face-to-face. All the participants worked at steel-producing factories in France. The likely exposure of each worker to metalworking fluids was estimated by experts, based on questionnaires and visits to the factories. The experts also investigated the duration, frequency and total cumulative amount of exposure. The analysis showed that the odds of developing bladder cancer increased with duration of exposure to straight MWFs in the 25 years prior to diagnosis. The finding still held after adjusting the data to take into consideration smoking and exposure to some other chemicals. There was also an increase in risk with exposure to soluble MWFs, but it was not statistically significant. There were no significant associations found with exposure to synthetic MWFs or with exposures more than 25 years before diagnosis. The increase in risk is attributed to the presence of carcinogens, such as polycyclic aromatic hydrocarbons, in the mineral oils present in straight and soluble MWFs. These compounds are also found in diesel exhaust, which the International Agency for Research on Cancer found to have a positive association, with limited evidence, with an increased risk of bladder cancer[ii].
Other studies have investigated metalworking fluids and bladder cancer, with mixed results. For example, a study of female autoworkers found no elevated bladder cancer risk from exposure to MWFs[iii], whereas a large study of automotive workers in the USA found an increased risk of bladder cancer with exposure to straight MWFs[iv]. The authors of the new study suggest that exposure prevention is necessary in sectors where MWFs are used.
[i] Colin, R., Grzebyk, M., Wild, P., Hédelin, G. & Bourgkard, È. Bladder cancer and occupational exposure to metalworking fluid mist: a counter-matched case–control study in French steel-producing factories. Occup Environ Med oemed-2017-104666 (2018). doi:10.1136/oemed-2017-104666 http://oem.bmj.com/content/early/2018/01/25/oemed-2017-104666 (Accessed 30 January 2018)
[ii] IARC: Diesel engine exhaust carcinogenic. International Agency for Research on Cancer, Press Release no 213, 12 June 2012. https://www.iarc.fr/en/media-centre/pr/2012/pdfs/pr213_E.pdf
[iii] Friesen, M. C., Betenia, N., Costello, S. & Eisen, E. A. Metalworking fluid exposure and cancer risk in a retrospective cohort of female autoworkers. Cancer Causes Control 23, 1075–1082 (2012). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3370111/ (Accessed 30 January 2018)
[iv] Friesen, M. C., Costello, S. & Eisen, E. A. Quantitative Exposure to Metalworking Fluids and Bladder Cancer Incidence in a Cohort of Autoworkers. Am J Epidemiol 169, 1471–1478 (2009). https://academic.oup.com/aje/article/169/12/1471/170464 (Accessed 30 January 2018)