Study of Cypermethrin Cytogenesis effects on Human Lymphocytes Using In-Vitro Techniques

The Cytogenetic effects of Cypermethrin a synthetic pyrithroid insecticide was investigated on human lymphocytes cultured in-vitro. Utilizing the trypan blue dye exclusion technique assay the LC50 of cypermethrin was found to be 36 uM. Based on LC50 value, cypermethrin was found to be low toxic to lymphocyte culture. Cypermethrin showed an increase in the frequency of chromosomal aberrations and found to be significant. Karyotype analysis revealed more satellite associations and chromosomal breaks in cypermethrin treated samples. Low-doses of the pesticide also induced singlestrand breaks in the DNA as assessed by comet assay. The pesticide caused increase in the comet tail length with increase in pesticide concentration, implicating genotoxicity in somatic cells. It is concluded that In vitro assays could give important information of the mechanism of toxicity at low dosages and impact on genetic material of human origin. @JASEM Pyrethriods are synthetic analogues of pyrethrins, the active substances in the flowers of Chrysanthemum, Cineraria folium. Pyrethroids can be classified into two large groups. Type I pyrethroids do not contain a cyano group in their molecules and include allethrin, tetramethrin, permethrin, and phenothrin. Type II pyrethroids contain a cyano group at the _ carbon position and include newer compounds, such as deltamethrin, cyphenothrin, cypermethrin, and fenvalerate. The two types of pyrethroids cause somewhat different symptoms of mammalian poisoning. Poisoning with type I pyrethroids is characterized by hyper excitation, ataxia, convulsions, and eventual paralysis; poisoning with type II pyrethroids, by hypersensitivity, choreoathetosis, tremors, and paralysis. Despite differences in the symptoms, both types of pyrethroids have the same major target site; the sodium channel of nerve membrane, i.e., the channel directly responsible for generating action potentials (Biologic basis of Neuro toxicity., 1992). Cypermethrin has become one of the most important insecticides in wide scale use. It has wide uses in cotton, cereals, vegetables and fruit, for food storage, in public health and in animal husbandry. Cypermethrin, an analogue of pyrethrins is classified by the World Health Organization (WHO) as moderately hazardous (class II). It interacts with the sodium channels in nerve cells through which sodium enters the cell in order to transmit a nerve signal. These channels can remain open for up to seconds compared to the normal period of a few milliseconds, after a signal has been transmitted (Clark et al., 1989). Cypermethrin also interferes with other receptors in the nervous system. The effect is that of long lasting trains of repetitive impulses in sense organ (Abbassy et al., 1983). Since cypermethrin is highly toxic to fish and bees, humans are indirectly affected as humans consume fish in their food and also honey which is made by the bees. Thus humans can be exposed to cypermethrin toxicity directly through spraying or contact methods or indirectly through consuming the pesticide-contaminated products like fish and honey. Hence there is a need for evaluating the toxicity at low doses, which can be studied easily using in vitro methods. The aim of the present investigation is to evaluate the cyto and genotoxicity of cypermethrin at low doses. The In vitro model system has been used instead of the animal model studies. The oral LD50 for cypermethrin in rats is 250 mg/kg (in corn oil) or 4,123 mg/kg (in water) (Meister., 1992). There is little human evidence that pyrethrins or pyrethroids cause health problems due to exposures. However, several animal studies have given us reasons for concern, specially the widespread use of these