The record
FDA proposed requiring TEM in tandem with PLM because, in FDA's words, many chrysotile and asbestiform amphibole particles in talc are not detectable by PLM at all, and PLM-only analysis may produce false negatives.
Claim scope
Answers the page's central question — whether 'no asbestos detected' means 'no asbestos present' — in the agency's own voice: it depends entirely on the method. FDA states the PLM-in-tandem requirement 'is consistent with established scientific opinions recognizing the limitations of PLM in the realm of analysis for asbestos in talc ... which may result in false negative test results,' and that 'a PLM method alone does not provide sufficient sensitivity.' FDA notes SEM/EDS 'can only be regarded as a complementary technique but not as a substitute for TEM/EDS/SAED.'
What this source does not establish
Does not quantify a false-negative rate for PLM. Does not establish that any specific past PLM-negative result was wrong.
Limitations
FDA's own FY2019 data table independently corroborates this: seven of the nine TEM-positive samples were PLM-negative. The FY2019 table's own footnote states 'PLM is not confirmatory of a negative finding. TEM is needed for confirmation.'
Source
Federal Register — 89 FR 105490 (Dec. 27, 2024), FR Doc. 2024-30544