Animal experiments on the allergenicity of d-limonene--the citrus solvent

With the increasing use of d-limonene as a substitute for chlorinated hydrocarbons, chlorofluorocarbons (CFC) and other organic solvents, a demand has arisen for more knowledge of the health effects of this substance. The aim of the present study was to investigate the allergenic effect of d-limonene on skin. The sensitizing potential of d-limonene and the influence of air exposure on its allergenicity were studied in guineapigs. d-Limonene of high purity gave no significant allergic reactions, while d-limonene exposed to air for 2 months sensitized the animals. Gas chromatographic analyses indicated that the content of limonene oxide in limonene increased with prolonged air exposure. It is concluded that allergenic compounds are formed from d-limonene upon prolonged air exposure. Products containing d-limonene should therefore be kept in cold storage in closed vessels. Manual handling should be avoided, or gloves worn, in order to reduce the risk of sensitization.