CYTOTOXICITY AND DNA STRAND BREAKS INDUCED BY BENZENE AND ITS METABOLITES IN CHINESE-HAMSTER OVARY CELLS

The cytotoxicity of benzene (BZ) and its major metabolites phenol (PHE ), hydroquinone (HQ), catechol (CAT), 1,4-benzoquinone (BQ), 1,2,4-ben zenetriol (BT), trans,trans-muconic acid (ttMA) and S-phenyl-mercaptur ic acid (S-PMA) was assessed by exposing Chinese Hamster Ovary (CHO) c ells to these compounds, Benzene was the least toxic (LD(50) = 20 mM), while BQ showed the highest potency (LD(50) = 10 mu M), followed by H Q (LD(50) = 40 mu M). It was found that the trend of cytotoxicity was: BQ > HQ much greater than CAT > ttMA > BT > S-PMA much greater than P HE > BZ, 1,4-Benzoquinone and HQ also demonstrated considerable abilit y to induce DNA strand breaks in CHO cells, which was assayed using th e fluorimetric analysis of DNA unwinding, The other metabolites were u nable to cause DNA strand breaks, When HQ was administered in combinat ion with other metabolites, no synergism was observed in the induction of DNA strand breaks, From these results, it can be seen that BQ and HQ are the most bioreactive species among the benzene metabolites when tested on CHO cells, Differences between the results obtained in our study and other studies were discussed.