**1. Introduction**

Over decades, consumption of pesticides has slightly increased year by year; over 4 million tons of pesticides were used worldwide in 2017. Asia (52.8%) followed by USA (30.2%) and Europe (13.8%) were the highest amount of pesticide used obtain the most excessive amount of pesticide used continents. Insecticides, a subgroup of pesticides, constitute nearly 100ooo tons per year [1]; and, carbamates, chlorinated hydrocarbons, organophosphates and pyrethroids are most commonly used insecticides. Although these chemicals increase crop yields and provide economic benefits by reducing pest-borne diseases, their harmful effects on human health and environment still have the attention; and, considering these effects less toxic alternatives continue to be developed. Pesticide exposure alone or in mixture via environmental contamination could have important acute and chronic adverse effects on living organisms. Pesticide usage in agriculture is increasing every passing day and becoming a confusing issue due to the use of new chemical compounds that come into the market.

Chronic or delayed insecticide exposure exerts its toxicity on several systems such as nervous, immune, respiratory and reproductive. Reproductive toxicity of insecticides may affect either men or women; reduced fertility, spontaneous abortion, birth defects and developmental retardation have been linked to insecticide toxicity [2, 3]. For livestock industry, decreasing reproductive functions is rising problem; and, common problems can be listed as infertility, sub-fecundity, ovarian cycle failures, decreased pregnancy rates, altered germ cell quality, reduced sperm motility as well as structural damage of testes or ovaries [4]. Furthermore, insecticides have important impacts on HPG axis and that qualifies them as endocrine disrupters. Endocrine-disrupting insecticides alter hormone synthesis or impair hormonal metabolic pathway by acting as hormonal receptor agonist or antagonists [5].

This chapter describes the reproductive system toxicity of commonly used insecticides based on each male and female; furthermore, it focuses on endocrine disruption.
