A Review of the Toxicology and Epidemiology of Wollastonite

Abstract

Wollastonite is a naturally occurring calcium silicate (CaSiO(3)) that is produced in both powder and fibrous forms. It is a valuable industrial mineral used in plastics, ceramics, metallurgical applications, paint, and friction products. For some applications wollastonite serves as an asbestos replacement. To varying degrees, wollastonite grades contain respirable particles/fibers, some of which have lengths and diameters that might be biologically active if deposited and retained in the lung. In this review we provide background information on wollastonite properties, markets, production and use, regulatory classification, and occupational exposure limits. We also summarize the available studies on the toxicology and epidemiology of wollastonite. We conclude that there is inadequate evidence for the carcinogenicity of wollastonite in animals and, based on strong evidence that wollastonite is not biopersistent, believe that a well-designed animal inhalation bioassay would have a negative result. The epidemiological evidence for wollastonite is limited, but does not suggest that workers are at significant risk of an increased incidence of pulmonary fibrosis, lung cancer, or mesothelioma. Morbidity studies have demonstrated a nonspecific increase in bronchitis and reduced lung function. It is prudent, however, to continue product stewardship efforts by wollastonite producers to control workplace exposures and to monitor scientific developments.

Are pleural plaques an appropriate endpoint for risk analyses?

“…The calculated standard mortality ratios for all neoplasms and cancer of the lung and bronchus for both men and women were less than unity, which fails to indicate that wollastonite is carcinogenic. Wollastonite toxicity has been the subject of review articles (Maxim & McConnell, 2005;Maxim et al, 2014) that indicate that this fiber is unlikely to be carcinogenic. Studies have suggested that exposure to mineral wool may be associated with the development of pleural plaques (Sandén & Järvholm, 1986;Järvholm et al, 1995).…”

Effects of wollastonite on the properties of medium-density fiberboard (MDF) made from wood fibers and camel-thorn

“…It has minimal effects on humans or wildlife, although long term exposure studies have not yet been performed (Huuskonen et al 1983, Maxim & McConnell 2005, Maxim et al 2014a. Wollastonite has a high thermal conductivity coefficient that could accelerate the transfer of heat from hot-press plates and facilitate resin curing in the center of the mat (Taghiyari et al 2013b(Taghiyari et al , 2014b.…”

Effects of the Improvement in Thermal Conductivity Coefficient by Nano-Wollastonite on Physical and Mechanical Properties in Medium-Density Fiberboard (MDF)

“…As far as the environmental aspects and health issues are concerned, wollastonite is known to be a non-toxic mineral that is not hazardous to humans or wildlife, unlike other mineral insoluble dusts like perlite that was reported to entail risks (Maxim et al 2014a). In fact, a review of the available epidemiological studies on wollastonite provides no evidence to suggest that wollastonite presents a health hazard; earlier studies on workers exposed to wollastonite dust indicated a need for further study of the health hazards to be carried out to come to a final conclusion (Huuskonen et al 1983;Maxim and McConnell 2005). However, a recent study on epidemiology and toxicity of wollastonite summed up that no pleural plaques or interstitial lung disease or decrements in lung function were observed among both never smokers as well as former smokers occupationally exposed to wollastonite (Maxim et al 2014b).…”