Pesticides Mechanisms of Action in Living Organisms

Abstract

Pollution is a phenomenon, which leads to ecological disequilibrium (alteration of biotic and abiotic) and may produce dangerous waste. Epidemiological studies, evaluate the relationship between the pollutants impacts over individual or collective risk and environmental factors. The rational use of pesticides in conjunction with other technologies may be justifiable in integrated pest management, the balance between benefits and effects being very complex. Pesticides are considered persistent pollutants, and may be classified according to chemical structure in the following main classes: organophosphates, carbamates, organochlorines, triazines, and pyrethroids. In this paper we present the mechanisms of action of the main pesticide classes in living organisms and especially in the human body. Organophosphate pesticides act on acetylcholinesterase, leading to development of cholinergic toxicity, because they decrease its enzymatic activity. The carbamate or phosphate pesticides inhibition of acetylcholinesterase, disrupts the equilibrium between acetylcholine synthesis and release on one hand and its hydrolysis on the other, and leads to its accumulation at synaptic level, with prolonged activation of cholinergic receptors. Organochlorine pesticides are highly lipophilic, and this property enhances their stability in living organisms and in the environment. They are largely stored in adipose tissue, a process called bioaccumulation, and this characteristic leads to the development of high toxicities in mammals. Triazines in high concentrations have been linked to increased cancer risk and incidence of birth defects. The pyrethroid insecticides acting on the sodium channels in the nerve membrane (neurotoxic), have high selectivity for insects, and do not have carcinogenic, mutagenic and teratogenic effects. Living organisms and humans are concurrently exposed to pesticides from more than one source, via the environment and food, and these may have a combined (synergistic or antagonistic) action, which can cause higher or lower toxic effects, in comparison with the situation of a single pesticide. © Springer Science+Business Media Dordrecht 2013.