Abstract: 【ABSTRACT】 BACKGROUND＆AIM: To study the mutagenicity and cumulative toxicity of terbutryn. MATERIALS AND METHODS: Strains TA97,TA98,TA100 and TA102 with or without S9 were used for Ames test (at doses of 0.5,1.0,2.0 and 5.0 mg/plate).Also used micronucleus assay of polychromatic erythrocytes (at doses of 400,800 and 1 600 mg/kg) and spermatogonia chromosome aberration test on mice (at doses of 200,400 and 800 mg/kg). RESULTS: Ames test showed that terbutryn group didn't cause double increase of revertants with or without S9 addition in any of the bacterial strain. Four doses, 0.5,1.0,2.0 and 5.0 mg/plate showed no dose-response relationship .No significant difference was found in the micronucleus test and the chromosome aberration test between negative control group and test groups. There was significant difference between those groups and positive control group. Seven days later half of the mice died of cumulative toxicity test. Its cumulation coefficient is 1.4. CONCLUSION: Terbutryn had no mutagenic effect according to these tests but showed significant cumulative toxicity.

Key words: terbutryn, Ames test, micronucleus assay, cumulative toxicity