Mesothelioma and asbestos exposure

The discovery that exposure to certain types of asbestos is linked to pleural mesothelioma is a result of the pioneering work of Dr. Christopher Wagner, who documented the high incidence of the disease amongst people working at or living near crocidolite (blue) asbestos mines as well as in household members of workers at these mines. Later research by Newhouse and Thompson (1965) also found elevated mesothelioma risks amongst workers (and their household members) at a manufacturing plant using crocidolite. Generally, once diagnosed, cases of mesothelioma are rapidly fatal, but the very long latency of the disease means that symptoms may only begin to appear 20, 30 or even more than 50 years after initial exposures. From the 1940s through to the 1970s, crocidolite and another amphibole, amosite, were used extensively, either alone or in conjunction with chrysotile, in friable insulation applications in the ship-building and construction industries, primarily in North America and Europe. These sprayed-on applications have been discontinued since the 1970s. To a lesser extent, amphiboles were also used in the manufacture of asbestos-cement pipe. In the past, in most of these industries, workers were exposed to extremely high fibre levels. However, what is particularly disturbing is that a number of cases of mesothelioma have been reported in individuals who have had relatively short but intense exposure to amphiboles. The discovery of mesothelioma and its association with certain types of asbestos exposure prompted new research programmes, regulatory attention and increased public awareness of the health risks of asbestos.