IN DEFENSE OF THE TERM “NATURALLY-OCCURRING ASBESTOS”

Asbestos is a commercial and regulatory term applied to six fibrous (asbestiform) minerals: the serpentine mineral chrysotile, and the fibrous varieties of five amphibole minerals, tremolite, actinolite riebeckite, cummingtonite-grunerite, and anthophyllite. Although initial recognition of the negative effects of asbestos inhalation came from heavy occupational exposures, years of research has clearly demonstrated that low levels of exposure can also produce negative health outcomes. In recent decades, research also has shown that exposure to fibrous amphiboles outside the regulatory definition (e.g. winchite at Libby, Montana) and fibrous zeolite minerals (e.g. erionite in Cappadocia, Turkey) represents a health risk equal to or greater than exposure to regulated asbestos minerals.

In recent years there has been increased awareness of the potential health risks of non-occupational and environmental exposures to asbestos and asbestos-like minerals that are present as natural components in rocks, sediments, and soils. The term “naturally occurring asbestos” has been used to describe such asbestos occurrences (including non-regulated fibrous minerals with known toxicity). Some researchers have taken issue with the term naturally occurring asbestos, arguing that all asbestos minerals are natural. Here we argue for the validity of the term naturally-occurring asbestos (NOA) because “naturally” is an adverb modifying “occurring” not an adjective modifying “asbestos” (hyphen added for clarity). Here, we introduce a new term, “commercially-modified asbestos” (CMA) to contrast with NOA and to describe asbestos minerals that have been mined, processed, refined and manufactured into products. The distinction between NOA and CMA is important when considering the life cycle of asbestos fiber populations (size and morphology), in assessing toxicity (related in part to morphology), in understanding potential differences in human exposure pathways, in developing appropriate monitoring strategies and risk assessment models, and in improving diagnostic protocols (e.g. patient histories).