The aim of this work was to assess the damage of DNA in human blood cell and sperm in vitro under the influence of furan. These cells were administered 0-600 mu M of furan at 37 and 32 degrees C for 30 and 60 min, respectively. A significant increase in tail DNA%, tail length and moment indicating DNA damage was observed at increasing doses when compared to the controls. The treatment with 300 and 600 mu M of furan showed a maximum increase of 86.74 +/- 2.43 and 93.29 +/- 8.68 compared to the control tail DNA% in lymphocytes. However, only 600 mu M of furan showed a maximum increase of 94.71 +/- 6.24 compared to the control tail DNA% in sperm. The results suggested that furan caused DNA damage in lymphocytes at increasing doses, but appeared to have not the same effect on human sperm at the low doses. Genotoxic activity had an impact on the risk assessment of furan formed on the food for human cells. Therefore, it would be important to further investigate these properties of furan as the food mutagen.