Chromosomal damage induced by herbicide contamination at concentrations observed in public water supplies

Herbicide contamination of natural resources, specifically groundwater, has drawn considerable public attention in recent years. Although deleterious effects of herbicides at large dosages have been well documented, information is lacking about the possible effects of herbicide levels that are found in public water supplies. Chromosomal damage is examined by flow cytometry on Chinese hamster ovary (CHO) cells that are exposed to three herbicides (atrazine, simazine, and bentazon) at concentrations deemed safe by the U.S. Environmental Protection Agency (USEPA) for drinking water. A known clastogen (ara-C) is also included as a reference for comparing the magnitude of chromosomal damage caused by herbicides. Chromosomal damage was assessed by measuring the coefficient of variation (CV) and percent chromosomes present in the larger chromosome distribution peaks. Exposure to atrazine (6-chloro- N-ethyl-N'-(1-methylethyl)-1,3,5-triazine-2,4-diamine) increased the CV of the largest chromosome distribution peak at concentrations considered safe by the USEPA. Chromosomes exposed to both simazine (6-chloro-N,N'-diethyl- 1,3,5-triazine-2,4-diamine) and bentazon (3-(1-methylethyl)-(1H)-2,1,3- benzothiadiazin-4(3H)-one 2,2-dioxide) did not exhibit chromosomal damage. Further analyses carried out on atrazine concentrations about equal to levels found in public water supplies revealed the potential of atrazine to induce chromosome breakages in CHO cells. Atrazine concentrations that were manyfold greater than the contamination limits exhibited a true clastogenic nature like ara-C. The results provide evidence for further investigations as to the potential health risk of consuming water contaminated with atrazine.