Herbicides in Argentina. Comparative evaluation of the genotoxic and cytotoxic effects on mammalian cells exerted by auxinic members

SOLONESKI, S.; LARRAMENDY, M L

Herbicides and Environment

INTECH

Lugar: Vienna, Austria, European Union; Año: 2011; p. 515 - 530

Worldwide, living species are unavoidably exposed to pesticides which represent a serious concern at both ecological and public health levels due to their toxicity. Furthermore, agrochemicals are ubiquitous on the planet since anthropic activities are continuously introducing extensive amounts of these substances into the environment. In epidemiological and in experimental genotoxic and cytotoxic studies, the existence of an increasing interest in biomonitoring markers to achieve both a measurement and an estimation of biologically active/passive exposure to genotoxic pollutants, is nowadays a real fact. Despite of the beneficial effects committed to the agricultural and household use of agrochemicals, many of them may represent potential hazards due to the contamination of food, water, and air, which can result in severe health problems not only for humans but also for ecosystems. The use of pesticides banned in industrialized countries, in particular, highly toxic pesticides as classified by the World Health Organization, the Environmental Protection Agency, and the International Agency on Research on Cancer, obsolete stockpiles and improper storage techniques may provide unique risks in the developing world, where 25% of the global pesticide production is consumed. In emerging countries, where there is insufficient regulation, lack of surveillance systems, less enforcement, lack of training, inadequate or reduced access to information systems, poorly maintained or nonexistent personal protective equipment, and larger agriculturally based populations, the incidences are expected, then, to be higher. The impact of increased deregulation of agrochemicals in the region threatens to increase the incidence of pesticide poisoning, which has already been termed a serious public health problem throughout Latin America by the World Health Organization. Because of the social, economic and cultural conditions under which they are used, pesticides acutely poison hundreds of thousands each year, including many children. In the majority of Latin American countries, poisoning registries are so inadequate that most acute poisoning cases never get recorded. Meanwhile, health effects of chronic or long-term pesticide exposures such as cancer or birth defects are not available, omissions that serve to hide the epidemic proportion of pesticide-related illness in the region. In Argentina, e.g., available official data revealed that 79% of the intoxications due to pesticides are related with the use of herbicides followed by insecticides and fungicides, values that correlate with the evolution of the phytosanitary market demonstrating that herbicides accounted for the largest portion of total use (69%), followed by insecticides (13%), and fungicides (11%) (www.casafe.org). In agriculture, pesticides are generally not used as a single active ingredient but as part of a complex commercial formulation. In addition to the active component, the formulated products contain different excipients, some of which have been reported to induce damage in mammalian cells, among others. Hence, risk assessment must also consider additional toxic effects caused by the excipient/s. Thus, both the workers as well as non target organisms are exposed to the simultaneous action of the active ingredient and a variety of other chemical/s contained in the formulated product. In the present report we evaluate comparatively the genotoxic and cytotoxic effects exerted on mammalian cells in vitro by two auxinic pure herbicides and their technical commercial formulations commonly used in Argentina. We selected the 2,4-D and 2,4-D DMA® (60.2% 2,4-D, Delente Laboratories SRL, Buenos Aires, Argentina) and Dicamba and Banvel® (57.7% Dicamba, Syngenta Agro S.A., Buenos Aires, Argentina), since although belonging to different groups of herbicides, i.e., phenoxy and benzoic families, respectively, they share a common mechanism of action. Evaluation was performed using end-points for genotoxicity [Sister chromatid exchanges frequency and Comet Assay] and cytotoxicity [Mitotic index, Cell viability, Proliferative rate index, and 3(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and Neutral Red assays]. Overall, the results clearly demonstrated that the damage induced by the commercial formulations of both herbicides is in general greater than that produced by the pure pesticides, suggesting the presence of deleterious components in the excipients with a toxic additive effect over the pure agrochemicals. Finally, the results remark that a complete knowledge of the toxic effect/s of the active ingredient is not enough in biomonitoring studies as well as that herbicide/s toxic effect/s should be evaluated according to the commercial formulation available in market. Furthermore, the deleterious effect/s of the excipient/s present within the commercial formulation should not be either discarded nor underestimated.