An in vitro study of cytotoxicity of organophosphate insecticides (Imidacloprid, Profenofos, Dichlorvos) and natural products (Neem oil and Dashparni ark) on human peripheral lymphocytes by MTT and Trypan blue assay

Abstract

It is a well-known fact that the human population of India is increasing very fast. Everybody needs food to survive. Agricultural products must be boosted by adding adequate fertilisers and using appropriate insecticides. Organophosphates are one of the most frequently used insecticides. Their overuse leads to soil contamination by agricultural runoff. The insecticides may enter drinking water as well. Since organophosphates are acetylcholinesterase inhibitors, they can be dangerous for human health if abnormal amounts are present in drinking water or are consumed as residues on fruits and vegetables. Hence, a toxicity study by MTT and Trypan Blue Assay of three common insecticides (Imidacloprid, Profenofos, Dichlorvos) and two natural products (Dashparnik ark and Neem oil) on lymphocytes was taken up. The insecticides were used at concentrations of 1mM, 4mM, 8mM and 12mM. It was found that at 4 hours of incubation at 1mM Imidacloprid showed the greatest drop in viability followed by Dichlorvos and the least harm was caused by Profenofos. The drop was consistent and dose dependent in the case of Profenofos, whereas at a higher concentration the viability generally increased. For 18 hours of incubation, the same trend was observed, but the decrease and increase were more pronounced. In the case of Profenofos and Dichlorvos the viability percent rises above that of the control. It was probably due to the defense mechanism involving the P450 detoxification pathway of the cells, which is activated if they are exposed to a higher concentration of the damaging factors. This is also supported by other workers mentioned in the discussion section of this paper. The damage to the cells, as evident in the fall in viability, was of lesser magnitude when organic insecticides were used. In the case of Neem nano-drop emulsion, a significant fall in viability was noted only at 2mg/ml. However, it is not sprayed as a nano-emulsion because it is not particularly harmful. The fourth insecticide that was taken up for study was Dashparni Ark. In this case, at 5µl/ml of distilled water (obtained by dilution) very little damage was evident, but at higher concentration it boosted the viability. Apparently, the extract of leaves fermented in cow urine and cow dung was less damaging than that of other insecticides. Thus, organic insecticides are safer to use because they are ecofriendly and do not harm non-target organisms. This is written on the basis of MTT assay results.