Abstract:

OBJECTIVE: To study the combined acute toxicity of different concentrations of melamine and cyanuric acid (M+C) in KM mice，and calculate the corresponding median lethal dose (LD50). METHODS：240 SPF Kunming mice were randomly divided into 20 groups，each group 12 mice，male and female in half. Three proportions of melamine and cyanuric acid (1∶1，2∶1 and 1∶2) were infused with the spray by single oral injection into mice，and Karber has used to explore the combined acute toxicity of M+C mixture. Six dose groups were treated in each proportion，for 109，173，274，435，689 and 1 092 mg/kg，respectively，and orally capacity was 0.02 mL/g. The same volume of corn oil was as the solvent control group and the blank control group at the same time. The growing states，deaths，body-weight and kidney viscera coefficient of mice were all observed for 14 days after administration， and median lethal dose was calculated. The mice were cervical dislocation to death in 15 days，and body-weight and kidney-weight of mice were checked. RESULTS：The median lethal dose of M+C (1∶1) in male mice was 274 mg/kg，and in female mice 401 mg/kg. The median lethal dose of M+C(2∶1) in male mice was 401 mg/kg，and in female mice 546 mg/kg. The median lethal dose of M+C (1∶2) in male mice was 344 mg/kg，and in female mice 589 mg/kg. The lethal dose of M+C mixture was 1 092 mg/kg，and the non-fatal dose was 173 mg/kg. Kidney damage was observed in experimental animals，which was swelled and some spot was seen. CONCLUSION：More toxicity was found with the mixture of M+C in 1∶1 ratio，and more in male mice than female mice. M+C mixture could induce renal toxicity. The combined toxicity of melamine and cyanuric acid was more than either alone.

Key words: melamine, cyanuric acid, nephrotoxicity, combined toxicity