Ocular irritation from product of pesticide degradation among workers in a seed warehouse

Four workers at a seed supply warehouse in Chiba Prefecture, Japan, complained of ocular irritation on the job. Pesticide-coated seeds were stored in the warehouse but no significant amount of pesticide was detected in the air inside the warehouse. To identify the cause of the ocular irritation and to determine an appropriate solution to the problem, the authors used thermal desorption gas chromatography-mass spectrometry to analyze the profiles of volatile organic compounds (VOCs) in the air of the two warehouses at the site—warehouse A, where the four workers experienced ocular irritation, and warehouse B, where no workers experienced ocular irritation. Comparing the profiles of VOCs in these warehouses indicated that n-butyl isocyanate, a hydrolyzed product of the fungicide benomyl, was the cause of the workers’ ocular irritation. n-Butyl isocyanate is known to be a contact irritant and if the benomyl-coated seeds were not properly dried before storage in the warehouse n-butyl isocyanate would have been produced. The results of the study suggest that more attention should be paid both to the pesticide itself and to the products of pesticide degradation. In this study, n-butyl isocyanate was identified as a product of pesticide degradation and a causative chemical affecting occupational health.