Several other groups in North America have been studied to determine the effects of asbestos exposure.
Railroad machinists
Railroad machinists were exposed to significant amounts of mostly chrysotile asbestos, especially during the application and removal of asbestos insulation on the boilers of steam locomotives. The last steam engine repairs took place in the late 1950s. In 1988 Mancuso published a study investigating the risk of mesothelioma among railroad machinists. His cohort was railroad machinists employed by a company before 1935, and stillalive in 1945. He analysed the data for 181 people hired from 1920 to 1929. By 1986, 156 were identified as dead. There were 41 cancer deaths, 14 with mesothelioma.
The relative risk was mesothelioma in every 13 machinists hired. Similarly, in 1986 Schenker completed a case-control analysis of mesothelioma among United States railroad employees. The United States Railroad Retirement Board notified investigators of all deaths among male railroad workers occurring in 1981–82. They reported 15 059 deaths during the study year. Twenty cases of mesothelioma were identified. More cases occurred among the workers in asbestos exposed job categories. The latency period was 30 years or more.
Jewelery industry
In the jewelery industry, asbestos has been used to make soldering forms. There have been case reports of mesothelioma among jewelery workers. However, Dubrow and Gute reported no cases of mesothelioma among 3141 Rhode Island jewelery workers who died during the decade 1968–78. This may have been a premature conclusion, since asbestos was not used in this industry in any significant amount until the 1940s. A cluster of 5 silversmiths with mesothelioma has also been observed in a Native American pueblo of 2000, where asbestos had been routinely used in the production of silver jewelery. After years of dispute, many of the investigators have come to some agreement: that amphiboles and particularly crocidolite are probably more carcinogenic than serpentines, but at high enough exposure levels, all the fiber types can cause mesothelioma.