Derivation of a chronic reference concentration for decalin

Abstract

Decalin is found naturally in crude oil and as a product of combustion. It is used commercially as a solvent due to its ability to solubilize oils and fats. Despite its widespread occurrence in consumer products and the environment that lead to inhalation exposures, an inhalation toxicity value is not currently available for decalin. To derive a reference concentration (RfC) for decalin, inhalation toxicity studies were reviewed using a weight-of-evidence approach. A 2-year mouse inhalation study was chosen as the critical study for the derivation of the chronic RfC. Benchmark dose modeling was utilized to derive a point of departure for hepatic necrosis, syncytial alteration, eosinophilic focus, and erythrophagocytosis. A BMDL10 of 44mg/m3 was modeled for the most sensitive adverse effect, syncytial alteration. A chronic RfC for decalin of 0.08mg/m3 was calculated by conversion of the BMDL10 to a human equivalent continuous inhalation dose of 7.9mg/m3 and application of a total uncertainty factor of 100. Future research is needed to better characterize the toxicity associated with the chronic inhalation of decalin and refine the development of toxicity values.