Objective   To confirm the suitable dosage of sulfur mustard(SM)in SD rats for screening the preventive and therapeutic drugs.

  Methods   SD Rats were used as the animal model, and four groups were established normal control group and three SM groups of different dosages, which were 3, 3.5 and 4 mg/kg(body weight)respectively.Diarrhoea rate and death rate, changes of body weight, general examination and clinical biochemistry of blood, cytological examination of bone marrow in week were observed to evaluate the toxic effetcs induced by different dosages of SM.

  Results   General status: There were no animals died in all groups, but the higher the dosage of SM, the higher the diarrhoea rate was, and the percentages were 0%, 20% and 75% respectively.Changes of animals body weight showed inverse proportion to the dosage of SM.General examination of blood: The higher the dosage of SM, the more significantly the difference contrasted to the normal control group, and especially the descent of leukocytes and lymphocytes were the most signficantly.Clinical biochemistry of blood: There was no significant difference between all groups.Cytological examination of bone marrow: All groups showed that proliferation of the marrow cells were active or very active, but the cytological classification were still obviously different.The lymphocytic ratio showed significantly decreasing tendency as the increasing of dosage of SM.However, the erythrocytic ratio showed increasing tendency, while the granulocytic ratio was not obviously changed.

  Conclusion   The dosage of 1mg/kg(body weight) of SM was the most suitable dosage for screening the preventive and therapeutic drugs in SD rat.