NONTOXICITY OF POLAR ABAMECTIN DEGRADATES FROM CITRUS-FRUIT AND THIN-FILM PHOTOLYSIS

After application to crops, abamectin (avermectin B1a plus avermectin B1b) degrades largely to a polar residue of unknown identity. Such polar degradates are also formed after photolysis of abamectin as a thin film on glass for approximately 1 day. To establish the safety of these residues, polar abamectin degradates were isolated from oranges treated with abamectin in the field and after photolysis of thin films on glass. These degradates were tested and found to have no adverse maternal or developmental effects in the CF1 mouse, the laboratory species/strain most sensitive to abamectin toxicity. In addition, the degradates from photolysis of thin films were negative in the microbial mutagenesis assay.