Perlite toxicology and epidemiology – a review

Abstract

Perlite is a generic name for an amorphous volcanic alumina–silicate rock that expands by a factor of 4–20 when rapidly heated to 1400–1800 °F (760–980 °C). Both the ore and the expanded product have extensive and widespread commercial applications. Limited data on the toxicology of perlite in animal studies indicate that the LD50 (oral ingestion) is more than 10 g/kg and, from a chronic inhalation study in guinea pigs and rats, that the NOAEL for the inhalation pathway is 226 mg/m3. Health surveillance studies of workers in US perlite mines and expansion plants (including some workers exposed to levels greater than prevailing occupational exposure limits (OELs) conducted over 20 years indicate that the respiratory health of workers is not adversely affected. Studies in Turkish mines and expanding plants had generally similar results, but are more difficult to interpret because of high smoking rates in these populations. A recent mortality study of permanent residents of the island of Milos (Greece) exposed to various mining dusts (including perlite) resulted in non-significant increases in standard mortality ratios for pneumonia and chronic obstructive pulmonary disease (COPD), whereas a companion morbidity study revealed elevated odds ratios for allergic rhinitis, pneumonia, and COPD when compared to another industrial area of Greece. Residents were exposed to other mining dusts and other possible causes or contributing factors and no ambient monitoring data were presented so it is not possible to use this study for risk calculations of perlite-exposed populations. Perlite is regulated as a “nuisance dust” in most countries.

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).…”

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.…”

Infrared detection of ore variability that influences the environmental risks during perlite mining and processing

“…Moreover, Cooper and Sargent (1986) indicated that perlite dust does not pose a significant health risk for workers. However, more recent studies, such as those conducted by Maisanaba et al (2015); Maxim et al (2014); Sampatakakis et al (2013), suggest that excess of exposure to perlite dust without the necessary protective equipment might result in adverse health effects. In addition, they indicate that the potential impact of the other minerals that are present in the perlite ore should not be underestimated.…”

“…Authorities such as the USEPA (1995) and USPC (2012) describe the fine particles generated during mineral processing and the content of metals in the ore as potential environmental risks and therefore are considered as cost penalties, which must be below certain thresholds. The fine particles are generally treated as nuisance dust; what is more, evidence provided by Elmes (1987) and Maxim et al (2014) suggests that in large amounts, these particles represent a factor of air pollution and a potential health risk for workers. Regarding the chemical purity, even though perlite is deemed to be an inert material, it has been mentioned before that the chemical composition of the ore can still be altered by the particular geological features of the deposit, which might result in an enrichment of elements that ultimately contaminate the ore.…”