Anthophyllite Asbestos: The Role of Fiber Width in Mesothelioma Induction Part 1: Epidemiological Studies of Finnish Anthophyllite Asbestos

Abstract

Anthophyllite asbestos only occurs in a few parts of the world in sufficient quantities to be mined. The largest deposits of anthophyllite asbestos occur in Finland where it was mined for more than 75 years and very extensively used and distributed, anciently, for more than six millennia. Anthophyllite is one of the five minerals known collectively as amphibole asbestos. Studies of the effect of these five mineral fibre types when inhaled have shown that fibre width is an important determinant of mesothelioma induction. Only the "thinner" fibres or those with fiber diameter dimensional profiles predominantly less than 0.25 -0.30 µm, are clearly mesotheliogenic. The "thicker" ones or those whose predominant widths are greater than these diameters do not appear to show an observable attendant risk of mesothelioma. Observations based on studies of at least, two "thick" forms of amphibole asbestos support these hypotheses. The one is Bolivian crocidolite; the other Finnish anthophyllite. The Finnish anthophyllite industry presents an important opportunity to study the robustness of the theory that fibre width is key to mesothelioma genesis as vast numbers of people in all sectors of the Finnish industry and their families have historically incurred massive fiber exposures sufficient to cause a gross excess of asbestosis. Nonetheless, in spite of these long term, high dose exposures clear evidence for a mesothelioma risk due to anthophyllite asbestos is still lacking.

Anthophyllite Asbestos: The Role of Fiber Width in Mesothelioma Induction Part 2: Further Epidemiological Studies of Occupational, Domestic and Environmental Exposure to Finnish Anthophyllite Asbestos

“…This is strongly supported by epidemiological observations of workers exposed to Finnish anthophyllite (e.g. Ilgren & Hoskins, 2018, Part 1 of this series) and demographic studies of large populations residentially exposed to Bolivian crocidolite (e.g. Ilgren et al, 2012a,b and2015).…”

“…This is important to the epidemiology for at least four reasons. Firstly, it enabled the Paakkila anthophyllite and various other minerals to be transported by boat to Kuopio or Joensuu and then, in some instances onwards more readily by train; because people from other parts of Finland and, indeed, wider Europe could enter Karelia; because, many thousands of years ago, it gave the stone age population access to the lake shores from which they could gather the anthophyllite asbestos to blend with the clay to make ceramic ware (see "The Ancient Finnish Anthophyllite Asbestos Ceramic 'Combware' Industry" in Ilgren & Hoskins, (2018)), and because Kuopio and Joensuu then became centers for ship and train manufacture and transport which periodically necessitated the use of commercial amphibole asbestos. Today, there is a "Russian" and a "Finnish" Karelia.…”

Anthophyllite Asbestos: The Role of Fiber Width in Mesothelioma Induction. Part 3: Studies of American and Japanese Anthophyllite Asbestos – Additional Supportive Evidence

“…The anthophyllite industry in the United States may be one of the first mining operations of the mineral in the New World, pre-dating "modern" Finnish mining and milling operations (Ilgren & Hoskins, 2018a) by nearly 75 years (McCallie, 1910). It was certainly the oldest asbestos industry in the United States (Bangs, 1946;Avery et al, 1958).…”

“…The soft nature of the weathered largely superficial naturally occurring deposits of anthophyllite asbestos which was preferentially mined, facilitated airborne release. Indeed, hundreds of naturally occurring deposits of anthophyllite asbestos are found across America but zones of endemic pleural plaques such as those seen in Finland (Ilgren & Hoskins, 2018a) have not been reported. Since pleural plaques are readily detectable radiologically and are sufficiently characteristic to be distinguished from other nonspecific pleural lesions, if they were present in significant numbers, they would have been reported.…”