Abstract:In order to evaluate the safety of the organic silicon adjuvant Breakthru S240 on Daphnia magna, this study investigated the acute toxicity, chronic toxicity and embryo toxicity, according to the commendatory standard test method namely experimental guideline for environmental safety evaluation of chemical pesticide. The 48h-LC50 value of the organic silicon adjuvant to D. magna was 1.218 mg/L, which belongs to the medium toxicity. The 21day chronic toxicity test showed that, the organic silicon adjuvant could significantly affect the breeding, length and sex differentiation, and the efficiency was more evident with the increase of concentration. The impact was not obvious for the growth and of F1(1st) after F0 being exposed to the organic silicon adjuvant. But it still showed significant differences for reproduction of F1(3rd) compared with the control group. It maybe have relationship with the exposed time. In addition, the organic silicon adjuvant had potential hazard to the development of embryo of D. magna and the inhibition rate reached to 68.50%.