Objective:To detect the effects of carbaryl exposure on sperm DNA damage,and explore the mechanism of carbaryl induced sperm DNA damage. Methods:A case-control analysis was conducted,including 31 male carbaryl exposure workers (exposure group),36 male administrators in the office in a pesticide factory (internal control group) and 22 male administrators in same area (external control group). The activity of semen SOD,the level of sperm ROS and the sperm apoptosis in three groups were compared. In cytotoxic experiments,GC2-spd cells were cultured with different doses of carbaryl. The cell survival rate,apoptosis rate,the production of ROS and the activity of SOD were measured. Results:The sperm DNA apoptosis and the level of sperm ROS in the exposure group were significantly higher than those in the internal and external control groups (P < 0.05). In addition,a negative correlation between the sperm apoptosis and semen SOD was found (r=-0.53,P < 0.001),while there was a positive correlation between the sperm apoptosis and sperm ROS (r=0.32,P = 0.002). Cytotoxic experiments showed that cell apoptosis rate and production of ROS increased,while the cell survival rate and the activity of SOD decreased at higher dose of carbaryl. Conclusion:Our findings suggested that occupational exposure to carbaryl production can cause the sperm DNA damage by oxidative stress.