A German research paper described four case of the asbestos cancer mesothelioma in brake mechanics. The cancer had been caused by asbestos dust, a component of brake (and clutch) linings. In 2014, the asbestos industry was still disputing this link.
R Paur and others. Pleural mesothelioma after asbestos dust exposure in brake repair work in automobile repair workshops: case observation, Praxis und Klinik der Pneumologie, volume 39, number 10, pages 362-366, 1985.