Fate of 3, 5-Xylyl Methylcarbamate Insecticide (XMC) in a Model Ecosystem

抄録

The fate of 3, 5-xylyl methylcarbamate insecticide (MXC) in a model ecosystem was investigated using three types of tracers : 3, 5-dimethyl-¹⁴C-, carbonyl-¹⁴C-, and N-methyl-¹⁴C-labeled XMC. XMC was rapidly degraded in water, although the peak of radioactivity in aquarium water of 3, 5-dimethyl-¹⁴C-XMC was comparatively higher than those of carbonyl-¹⁴C- and N-methyl-¹⁴C-XMC. More than 90% of the radioactivity remained in the aqueous phase when aquarium water was extracted with chloroform. Most of the radioactivity in algae, snails, and fish was not extracted with 66.7% aqueous acetonitrile. The amount of radioactivity extracted with 66.7% aqueous acetonitrile was slightly greater for 3, 5-dimethyl-¹⁴C-XMC than for carbonyl-¹⁴C- and N-methyl-¹⁴C-XMC. Most of the radioacitivity in solvent extracts of water existed as the parent compound, and that of organisms was found mainly in the lower portion of the TLC plate. From the concentration of intact XMC in water and organisms, ecological magnification (EM) was calculated. EM of XMC was comparatively small comparaed with those of organochlorine insecticides. There was little possibility of ecological magnification of residual XMC in higher animals due to food chain.