Guinea pigs were sensitized intracutaneously for 7 days (0.1 ml of 1% aldehyde solution/day) with nine aldehydes (p-anisaldehyde, benzaldehyde, citral, ethylvanillin, furfural, n-octanal, l-perillaldehyde, piperonal and vanillin) which are used as the food flavoring agents. Three weeks later, each aldehyde was injected by different concentrations (0.25-1.0%). Skin reactions were observed 24 hr after the injection of the aldehydes. All aldehydes tested exhibited a positive skin reaction, indicating that these aldehydes are capable of inducing an allergic reaction
