Industrial-grade talc exposure and the risk of mesothelioma

Abstract

Industrial-grade talc deposits are complex mixtures of mineral particles and may vary substantially in composition across small geographical areas. Typical industrial-grade talc includes amphibole cleavage fragments, platy talc, serpentine minerals, talc in fibrous form, and a minor presence of transitional fibers. Industrial-grade talc was erroneously determined to be an asbestos-containing material due to an unintended consequence of Occupational Health and Safety Administration’s (OSHA’s) method for measuring airborne asbestos mandated in 1972. This error was repeated, most notably, by the National Institute for Occupational Safety and Health (NIOSH) in, 1980 for talc mined in northern New York State (NYS) by RT Vanderbilt Company (RTV). Subsequent exposure studies of northern NYS talc conducted through the, 1980s and one study published after, 2000 relied on the conclusion that talc was an asbestos-containing material to infer a causal relationship between talc and mesothelioma. The present review included (1) publications concerning talc’s cancer-causing potential issued by organizations concerned with occupational and public health; (2) talc exposure studies and animal and cellular studies of RTV talc; (3) mesothelioma rates in northern NYS; and (4) mesothelioma mortality among RTV mining employees. The review indicated that failure to correctly identify the mineral characteristics of talc resulted in misleading reports concerning the carcinogenic potential of talc. However, the collective data from animal and cellular studies, mesothelioma rates in northern NYS, exposure studies, and a mortality analysis of RTV mining employees do not support a causal relationship between RTV talc and mesothelioma. This conclusion is applicable to all mineral components in RTV talc and to other industrial-grade talcs and mineral aggregates with the same components.

Keywords::

• Asbestiform–nonasbestiform
• NYS talc mining
• OSHA asbestos regulation talc minerals
• talc risk assessment

Acknowledgements

I thank John Kelse, Director, Occupational Health and Corporate Industrial Hygienist at RT Vanderbilt, for his assistance in obtaining information about RT Vanderbilt products, the mineralogy of New York State talc, and data concerning the ages and tenures of RT Vanderbilt’s mining and milling workforce at its Gouverneur mine in St. Lawrence County, NY. In addition, I thank Roger McClellan, Editor of Critical Reviews in Toxicology, and three anonymous referees for their comments, questions, and suggestions, which I used to improve the article.

Declaration of interest

The preparation of this report was funded in part by the RT Vanderbilt Company, Inc. I have served as a consultant to RT Vanderbilt concerning talc exposure and mesothelioma risk and I have been designated as an expert witness by RT Vanderbilt in lawsuits involving mesothelioma.

Notes

*amended from 0% and 0.005% in the original article published online ahead of print at www.informahealthcare.com/txc.