The National Toxicology Program (NTP) of the U.S. Department of Health and Human Services has published a draft technical report finding that ultraviolet ray-absorbing ingredient 2-hydroxy-4-methoxybenzophenone (HMB; benzophenone-3; CAS 131-57-7) has “equivocal evidence of carcinogenic activity” in rats. This level of evidence is the third level within five categories and is defined as representing “a marginal increase of neoplasms that may be chemical related.”
Two-year studies were completed in both mice and rats, exposing them to concentrations between 0 and 50,000 parts per million. It was found that exposure to benzophenone-3 in rats led to an increase of non-neoplastic lesions of the testis and pancreas in males and of the uterus and adrenal cortex in females. Increases in lesions were also observed in the bone marrow, spleen, and kidney of both sexes in mice.
Benzophenone-3 is often used in sunscreens as well as in synthetic resins and polymers. It is listed within the FACET inventory of food contact chemicals. The NTP will hold an expert panel meeting to complete a peer review of the draft report on December 12, 2019. Oral comments from the public during the meeting are welcome, and registration is open to join via webinar.
A draft technical report was also published by the NTP on perfluorooctanoic acid (PFOA; CAS 335-67-1) and will be reviewed during the same meeting.
NTP (2019). “NTP Technical Report on the Toxicology and Carcinogenesis Studies of 2-Hydroxy-4-methoxybenzophenone (CAS No. 131-57-7) Administered in Feed to Sprague Dawley (Hsd:Sprague Dawley®SD®) Ratsand B6C3F1/N Mice.” (pdf)
Emma Davies (October 16, 2019). “US NTP finds ‘equivocal evidence’ for oxybenzone carcinogenicity.” Chemical Watch