Notice of Retraction: Mutagenic Action of Milbemycin oxime

The objective of this study was to determine mutagenicity of milbemycin oxime by Ames, micronucleus and sperm malformation tests. In the Ames assay, four genotypic variants of the Salmonella strains (TA97, TA98, TA100 and TA102) carrying mutations in several genes were used. Milbemycin oxime was incubated with them in five different doses both in the presence and absence of metabolic activation (S9) and the result was assessed based on the number of revertant colonies. Concurrently, appropriate positive controls were used so as to validate the test. The average number of revertant colonies per plate treated with milbemycin oxime was less than double as compared to that of the negative control. In the micronucleus assay, Kunming mice were orally treated with 1/5, 1/10, 1/20 of the mice oral LD50, twice (24 h interval), respectively. At 6 h after the second time, all mice were killed and taken out of femur bones, then washed out the bone marrow to make smears on clean slides. 1000 PCE were scored by oil immersion lens. The numbers of micro-nucleated PCE were counted, the micronuclear rates were calculated. The obtained results indicated that milbemycin oxime could not induce the increase of micronuclear rates of PCE in bone marrow. In sperm malformation test, the effect of milbemycin oxime on sperm parameters was investigated following oral doses of 1/5, 1/10, 1/20 LD50 every 5 days for 35 days to male kunming mice. The treated groups showed no significant changes both in sperm abnormality and in a dose-dependent manner.