THE CLASTOGENIC POTENTIAL OF TRIAZINE HERBICIDE COMBINATIONS FOUND INPOTABLE WATER-SUPPLIES

Pesticide contamination of drinking water supplies has increased over the past decade. A major concern is how exposure to combinations of lo w levels of pesticides, especially herbicides, could affect public hea lth. Flow cytometric analysis was performed to determine the clascogen ic potential of herbicide interaction on Chinese hamster ovary (CHO) c ells. The cells were exposed to atrazine, simazine, cyanazine, and all possible combinations of these chemicals for 48 hr. Two concentration s were used for each sample: the U.S. EPA maximum contamination level (MCL) and the highest contamination level found in Illinois water supp lies. Nuclei were isolated from the cells and analyzed by flow cytomet ry. The effects of clastogenicity were measured by the coefficient of variation (CV) of the G1 peak of whole cells and the change in CV of t he largest chromosome in the flow karyotype. At both levels tested, at razine caused chromosomal damage to the CHO cells. Simazine was observ ed to induce whole-cell clastogenicity but not flow karyotype damage. Cyanazine did not induce any measurable chromosomal damage in either a nalysis. Each of the herbicides, although all three were triazines, ha d different effects with respect to chromosome damage as measured by f low cytometry. CHO cells treated with a combination of atrazine and si mazine, or atrazine and cyanazine, were observed to have whole-cell an d flow karyotype damage. This damage was, however, equal to or less se vere than the damage caused by either atrazine or simazine alone. No s ynergy was observed. When all three herbicides were combined, three of the four possible combinations gave no observable clastogenic respons e.