Sensitizing potential of acetaldehyde and formaldehyde using a modified cumulative contact enhancement test (CCET)

The contact allergenic activity of acetaldehyde was investigated with a mod ified cumulative contact enhancement test (CCET) method in guinea pigs. Pos sible cross-reactivity between acetaldehyde and formaldehyde was also studi ed. In contrast to the original CCET protocol, we used sham-treated control s and the chemicals were tested with closed epicutaneous application at Ist challenge. The suitability of the method was verified with formaldehyde an d the results were comparable with those previously found with the guinea p ig maximization test (GPMT). For the Ist time, acetaldehyde was shown to be a contact allergen in predictive tests. No cross-reactivity was observed b etween acetaldehyde and formaldehyde. Acetaldehyde seems to be a rare sensi tizer in man. However, its allergenic activity should be considered, since it might be present as an impurity in ethoxylated surfactants. As the CCET protocol involves topical induction and challenge, we regard the modified v ersion as well suited to evaluation of the contact allergenic potential of chemicals.