The record
A 1966 J&J internal test of 'historic baby powder' reported 'tremolite in domestic talc, Italian talc and fibrous talc' by microscopic examination, per the test inventory in Table 3 of PMID 33641519 — the earliest dated entry in the J&J testing record documented in the peer-reviewed literature.
Claim scope
That J&J's own 1966 testing detected tremolite in talc samples including historic baby powder, per the peer-reviewed inventory.
What this source does not establish
Does not establish the concentration, the habit (asbestiform vs cleavage fragment), or that the tested 'historic baby powder' was then in commerce.
Limitations
Present as the earliest dated item in the documented testing chronology; concentration language is not available for this test and must not be added.
Source
Pmid — 33641519