Degradation Behavior of Methyl Isothiocyanate in the Aquatic Environment

Methyl isothiocyanate (MITC) is a fumigant used to control nematodes, fungi, and insects in agricultural soils. Most of MITC used for agriculture is released into the environment. To examine the degradation behavior of MITC in an aquatic environment, a biodegradation test using an activated sludge was carried out. This test revealed that MITC is hardly mineralized, but converted to six metabolites, which were determined to be 1,3-dimethylthiourea, 3-methylamino-5-oxa- thia-2,7-diaza-2,6-octadiene, 3-methylamino-4,5-dithia-2,7-diaza-2,6-octadiene, methylamine, elemental sulfur, and carbon disulfide. The first three compounds have never been detected or predicted as products even in soil.