A study of cypermethrin insecticide toxicity on the reproductive system of adult male albino rats

Industrial revolution has gifted toxic chemicals such as pesticides which have become major contaminants of our environment and have been found in soil, air, water and even in animal and human tissues. These pesticides make injurious effects and even mortalities, most (about 99%) of which belong to the third world nations. During the last decades the use of pesticides has increased steadily in developing countries in an effort to increase food production and control vector-borne diseases. At present, there are more than 65,000 chemicals that are classified as pesticides. Synthetic pyrethroids comprise a class of universal pesticides, of which their usage is expected to increase. There are two types of these compounds type I and II. Cypermethrin (CYP), the alpha-cyano-3-phenoxybenzyl ester of 2,2-dimethyl-3-(2,2-dichlorovinyl)-cyclopropane-carboxylic acid, is the most widely used type II pyrethroid pesticide.Objectives: The aim of this work was to investigate the toxic effects of CYP on the reproductive system of adult male albino rats.Subjects and methods: One hundred ninety two adult male albino rats were used in this study. They were divided into 4 equal groups: Group I (negative control group): Forty eight rats were left without intervention to measure the basic parameters for 14 weeks. Group II (positive control group): Forty eight rats were divided in to two subgroups: Twenty four rats were orally gavaged with corn oil in a daily dose of 2 ml/kg/day for 8 weeks. The remaining twenty four rats were followed up without corn oil administration for another 6 weeks (follow up period). Group III (group A): Forty eight rats were given CYP by oral gavage in a daily oral dose of 50 mg/kg (1/5 LD50). Group IV (group B): Forty eight rats were given CYP by oral gavage in a daily oral dose of 25 mg/kg (1/10 LD50) then the same schedule was performed as for group III.Results: The results after being statistically analyzed and tabulated revealed the following: Throughout the whole period of the study, the control groups (negative and positive control groups) showed no abnormal findings as regard the all tested parameters with a non significant difference between control groups. In both treated groups (group A and group B), CYP induced toxic effects on the testes which were indicated by significant increases in testicular weight due to obvious edema. The toxic effects included a significant and gradual decrease in the mean values of serum level of testosterone hormone. The effect more prominent and showed significant decrease in group A more than group B meaning that the effect was time and dose dependent. Changes in seminal analysis were observed in the form of a significant reduction in the mean values of sperm count, percent of sperm motility, viability and a significant increase in sperm abnormal forms percent. These effects were time and dose dependent.Conclusion: Cypermethrin administration in a dose of 25 mg/kg/day (1/10 LD50) and 50 mg/kg/day (1/5 LD50) for 8 weeks has resulted in disturbance of the reproductive system of adult male albino rats. It causes endocrine disruption by decreasing the level of testosterone as compared to control group so; it can be linked to male factor infertility. Cypermethrin is a genotoxic chemical. These toxic effects were dose and time dependent. Follow up periods for 6 weeks resulted in partial improvement of the reproductive toxicity.