Contact dermatitis due to rubber boots worn by Japanese farmers, with special attention to 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline (ETMDQ) sensitivity

An investigation was conducted as follows in 9 farmers with contact allergy due to rubber boots: (i) patch tests with 19 rubber additives; (ii) chemical analysis of additives in 6 pairs of rubber boots; (iii) use tests on a hypoallergenic trial product in 5 patients. The following results were obtained: (i) in the patch tests, all 9 patients showed positive reactions to 1 or more of the nitrogen(N)-containing antioxidants (IPPD, DMBPPD, ETMDQ); (ii) ETMDQ was detected in 1 pair of rubber boots, and IPPD and DMBPPD in another pair; (iii) no patient using hypoallergenic boots during rice-planting had recurrent dermatitis. N-containing antioxidants, such as IPPD, DMBPPD and ETMDQ, were thus considered as the main causative agents and the trial product was found useful for managing contact dermatitis. Contact allergy due to ETMDQ in rubber is reported here for the 1st time.