38-6 A survey of microscopy data regarding asbestos contamination in some talc materials: Progress in understanding the nature of a geogenic carcinogen.

Session: Petrology and Geochemistry (Posters)

Presenting Author:

Authors:

Abstract:

The occurrence of asbestos and its association with talc is of importance to talc products. Talc is produced from several locations globally. For 2025, USGS information indicates China and India each produced approximately 1.4 million tons of talc as the global leaders, and the US produced approximately 530,000 tons of talc. Global production is estimated to be 6.9 million tons and global reserves are at least 500 million tons. Thus asbestos contamination in talc is a global issue and a major concern in the area of geohealth. The geologic association of asbestos minerals and talc has long been recognized for several decades. The recognition of the occurrence of asbestos in talc has been complicated and some historical issues with industry testing are discussed. General scientific consensus indicates that heavy liquid separation (HLS) sample preparation methods are most appropriate for detection of asbestos in mixed media and is recommended by the USFDA IWGACP 2021 whitepaper. Asbestos testing in several talc materials is presented from multiple sources. Recent initial STEM-EDS work shows promise for some asbestos and impurity issues in talc. Some common forms of asbestos detected in talc materials include chrysotile, tremolite, and actinolite. Anthophyllite and richterite are also observed. Additional examples of talc fibers are presented which are particles, that if they meet the USFDA IWGACP 2021 whitepaper criteria of greater than 500 nm in length and an aspect ratio of 3:1 should be counted. For the samples observed, the mineralogy of the asbestos in talc materials is consistent with the known geology for the source area of the talc materials. There are several geologic contexts of many talc deposits that promote the occurrence of asbestos minerals in talc ore and derived materials. These include but are not limited to protolith composition, protolith alteration, country rock that has asbestos that is disturbed during the mining process, thermal cooling of the talc ore itself over geologic time, and faulting. Combinations of these processes can occur and given some talc sources are on the order of billion years old, multiple such processes very likely occurred. Results point to the need for expanded and routine HLS based asbestos testing in the talc industry.

Geological Society of America Abstracts with Programs. Vol. 58, No. 1, 2026

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