Lead acetate
Formula: C4H6O4Pb
Molecular Weight: 330.0
Cas No：301-04-2; 15347-57-6
Hair coloring
EWG gives this a 10 on the toxicity scale as it is a mercury-based preservative. Might be a good idea to adjust toxicity ratings here as this looks pretty dangerous:
https://www.ewg.org/skindeep/ingredient/703511/LEAD_ACETATE/