Publisher Summary The use of pesticides in homes, schools, food, and water provides ample opportunity for human exposure. Organophosphates (OPs) are the most common pesticides in current use. In addition to the neurotoxicity of organochlorines, they have been shown to have effects on the endocrine system. Semen quality has been shown to be impaired by exposure to alachlor and atrazine, and the feminization of male frogs has been detected. Decreased acetylcholinesterase (AChE) activity is not the sole mechanism of OP neurotoxicity; the correlation between cholinesterase and pseudocholinesterase activities and neuronal damage is not strong. In addition to their action on AChE, OPs have been found to affect adenyl cyclase. Pyrethroids are synthetic molecules that chemically resemble the natural pesticide secreted by chrysanthemums. Although generally regarded as safe, pyrethroids are not innocuous; they both activate and inactivate gates of sodium channels, thereby resulting in prolonged opening, with membrane depolarization, repetitive discharges leading to excess nervous system stimulation, and hyperexcitatory symptoms.