Abstract: In order to explore the synergistic toxicity of phthalate acid esters （PAEs）， the bone marrow micronucleus formation， sperm deformity， liver and testis damage were carefully observed and determined on male mice， which were exposed to mixed PAEs chemicals with different levels of dose （40， 400， 4 000 mg·kg-1） and single dibutyl phthalate （DBP） with the same doses （40， 400， 4 000 mg·kg-1）. It was shown that the bone marrow micronucleus formation rate and sperm deformity rate were obviously higher in the mixed group with highdose （4 000 mg·kg-1） PAEs than those in the single DBP treatment. Besides， the damage of liver and testis was also higher in the mixed group with moderatedose （400 mg·kg-1） PAEs than that in the single DBP treatment after 30 d. As mentioned above， the mixed PAEs exhibited more severe toxic effects than single DBP treatment， which suggested that there might be certain synergistic effect among PAEs chemicals.

Key words: PAEs chemicals, male mice, bone marrow micronucleus formation rate, sperm deformity rate, synergistic toxicity