Only preliminary (pilot study) toxicity data are currently available for the food flavoring 2,3-pentanedione (PD). However, it is possible to compare the pilot study data for PD to similar data for diacetyl and derive an estimate of the relative toxicities of PD and diacetyl in mice. PD data were taken from a study described by Morgan et al.  (Toxicologist 114(1):316) and compared to a diacetyl pilot study, Morgan et al  (Tox. Sci. 103(1):169-180. In the PD study, rats and mice (6/dose group) were exposed to 0, 50, 100, or 200 ppm for 2 weeks + 2days. In the diacetyl study, male C57Bl/6 mice (5/dose group) were exposed to 0, 25, 50, or 100 ppm for either 6 or 12 weeks. The pathology produced by both chemicals was very similar, affecting nasal tissue most severely but also the trachea, larynx, and bronchi. Benchmark dose analysis compared the BMD50s for nasal suppurative exudate in male mice, and for bronchial inflammation in male mice for diacetyl and female mice for PD. Comparing the PD data to the 6-week diacetyl data for the nasal suppurative exudate endpoint, PD appears to be 73% (95% CI 30-177%) as potent as diacetyl. Comparing the PD data to the 6-week diacetyl data for the bronchial inflammation endpoint, PD appears to be 53% (95% CI 18-158%) as potent as diacetyl. Comparisons to the combined 6 + 12-week diacetyl data yield toxicity ratios of 67% (95% CI 32-141%) for the nasal endpoint, and 58% (95% CI 22-153%) for the bronchial endpoint. Although the central estimates suggest that PD may be somewhat less potent than diacetyl for the endpoints in question, given the wide confidence limits equipotency of PD and diacetyl cannot be ruled out based on the current data.
The Toxicologist. Society of Toxicology 51st Annual Meeting and ToxExpo, San Francisco, California, March 11-15, 2012