We have reported that many chrysanthemum- and lettuce-growers have dermatitis caused by juice of the leaves of these plants and that this dermatitis is caused by an allergic mechanism. In arecent questionnaire on the cause of this dermatitis, half the farmers answerd that it was due to agricultural chemicals. Therefore, we tested the farmers by skin patch tests with several widely used chemicals. In the tests, daconil gave the strongest reaction, results being positive in 60% of the farmers. Daconil was very irritative and phototoxic, the percentage of positive reactions in the patch test with 800 times diluted daconil solution of the concentration commonly used being about 30% after 48 hours and about 60% at 48 hours after peeling off the patch.
The parcentage of positive reactions in the skin patch test with several fractions of chrysanthemums on chrysanthemum-growers were significantly higher than non-farm-workers. Similary, tests with allergen extracted from lettuce showed a significantly higher percentage incidence in lettuce -growers than in other subjects. The patch test with 4000 times diluted daconil solution showed ahigher incidence in farmers than in other subjects. Therefore, 4000 times diluted daconil solution seems to cause allergic contact dermatitis in farmers, and as farmers reported, dermatitis seems to be caused by allergy to farm products, and the irritability, phototoxicity and allergenicity of TPN (Daconil).