Phenylurea herbicides induce cytogenetic effects in Chinese hamster cell lines

The intensive use of herbicides over the last few decades has caused a general increase of environmental pollution. It is thus very important to evaluate the possible genotoxic properties of these chemical compounds as well as identifying their mode of action. Phenylurea herbicides are selective agents widely used for the control of infestant plants. Of these herbicides, which are widely used in agriculture, we analysed four of the less intensively studied molecules. More precisely, we investigated the genotoxic effects of fenuron, chlorotoluron, diuron, and difenoxuron by analyses of chromosomal aberrations (CAs) and sister chromatid exchange (SCE) in exposed mammalian cells. We used the Chinese hamster ovary (CHO) and epithelial liver (CHEL) cell lines, endowed with the absence or the presence, respectively, of an enzymatic system to activate pro-mutagenic compounds. Our results show that all herbicides tested induce, at high concentrations, an increasing number of CAs in non-metabolising CHO cells. Instead, in the exposed CHEL cell line, the four herbicides induced CAs also at the lowest dose-level. In the CHEL cells, a statistically significant increase of SCE was also observed. The phenylurea herbicides showed direct genotoxic activity, but the cytogenetic effects were greatly enhanced after metabolic conversion. These data, together with other information on phenylurea herbicides, are of great interest from the environmental point of view, and for human health. In fact, intensive use of herbicides contaminates soil, surface water, groundwater and agricultural products, and thus should be taken in particular consideration not only for those initiatives to specifically protect exposed workers, but also to safeguard the health of consumers of agricultural products.