AbstractBackgroundDicyclohexylcarbodiimide (DCC) is known to cause occupational allergic contact dermatitis in biotechnology laboratory workers.ObjectivesThis study aimed to assess the prevalence of DCC sensitization among workers of one biosynthesis laboratory and to determine the optimal DCC concentration for patch testing.Materials and methods23 laboratory workers frequently exposed to DCC of whom 21 suffered from dermatitis and 11 controls were enrolled into the study. All participants underwent skin patch testing with different concentrations of DCC and other substances used in the work environment. Statistical analysis was conducted to compare results between active and control groups.ResultsOf the 23 workers tested, 56.5% showed positive reactions to DCC. All of them had dermatitis. Morpholine also elicited positive reactions in 26.1% of workers who were all sensitized to DCC. Dimethylformamide and chloroform yielded negative results.ConclusionDicyclohexylcarbodiimide was a major cause of contact dermatitis in the active group indicating an outbreak of contact allergy to DCC in the company necessitating preventive measures. Both DCC 0.1% ac. and DCC 0.05% pet. should both be used for patch testing.