• Elongate Mineral Particles

Lambert et al1 report on the relationship between exposure to elongate mineral particles (EMPs) and the incidence of mesothelioma among Minnesota iron ore miners. In a previous study, mesothelioma mortality was found to be increased among workers employed in the Minnesota mining industry.2 Based on 30 observed deaths, a standardised mortality ratio (SMR) of 2.77 with a 95% CI of 1.87 to 3.96 was found among the 31 067 workers most likely engaged in taconite mining and refining, as opposed to haematite mining. Taconite, but not haematite, mining and processing is known to entail exposure to non-asbestiform amphibole and non-amphibole EMPs (predominantly).

These results appear to be in contrast to the view that non-asbestiform EMPs are associated with little or no carcinogenic risk.3 However, the results were in agreement with the observation of an increased incidence of mesothelioma in Northeastern Minnesota, which is what initially prompted the mortality study of iron miners.4 The mortality study, however, as its …