The record
At the same hearing, a testifying geologist stated that asbestos and talc formation are linked by common geologic processes and that asbestos in cosmetic talc is a health hazard even at levels the industry J4-1 method labels non-detect.
Claim scope
A geological basis for expecting co-occurrence, in the record: 'although we often refer to asbestos as a contaminant in talc, as though it were an introduced foreign substance, asbestos can occur as a relic component of the natural talc-forming geologic processes, and its presence should be anticipated.' He also testified 'it is improbable for geologic processes to produce 100 percent pure talc in mineable volumes.'
What this source does not establish
Witness testimony, not a congressional finding. Does NOT establish that all talc deposits contain asbestos — the same witness testified that 'metasomatism of carbonate protolith at a specific temperature could produce asbestos-free talc.' That qualifier must travel with the claim; omitting it would misrepresent the testimony.
Limitations
Metcalf also flagged the cleavage-fragment question as contested: 'amphiboles occur in both fibrous and nonfibrous morphologies that leads to this issue of cleavage fragments.'
Source
Gov Report — CHRG-116hhrg38735 (Dec. 10, 2019), testimony of Dr. Rod Metcalf, University of Nevada-Las Vegas