Because OP pesticides degrade quickly when exposed to air and light, they have been considered relatively safe to consumers. However, OP residues may linger on fruits and vegetables. Certain OP pesticides have been banned for use on some crops, For example, methyl parathion is banned from use on some crops and permitted on others. It can also occur through deliberate poisoning using nerve agents such as sarin and tabun. Examples
Insecticides including malathion, parathion, diazinon, fenthion, dichlorvos, chlorpyrifos, ethion, trichlorfon
Nerve agents including soman, sarin, tabun, VX
Herbicides including tribufos [DEF], merphos are tricresyl phosphate–containing industrial chemicals.Exposure to any of the above-listed organophosphates may occur through inhalation, skin absorption, and ingestion, most commonly of food that has been treated with an OP herbicide or insecticide. Exposure to these chemicals can occur at public buildings, schools, residential areas, and in agricultural areas. Chlorpyrifos and Malathion have been linked to reproductive effects, neurotoxicity, kidney/liver damage, and birth defects. Dichlorvos has also been linked to reproductive effects, neurotoxicity, and kidney/liver damage. It is also recognized to be a possible carcinogen. Pathophysiology
The health effects associated with organophosphate poisoning are a result of excess acetylcholine (ACh) present at different nerves and receptors in the body because acetylcholinesterase is blocked. Accumulation of ACh at motor nerves causes overstimulation of nicotinic expression at the neuromuscular junction. When there is an accumulation of ACh at autonomic ganglia synapses this causes overstimulation of muscarinic expression in the parasympathetic nervous system.
For those males exposed to OP pesticides, poor semen and sperm quality have been seen, including reduced seminal volume and percentage motility, as well as a decrease in sperm count per ejaculate. In females menstrual cycle disturbances, longer pregnancies, spontaneous abortions, stillbirths, and some developmental effects in offspring have been linked to OP pesticide exposure. Prenatal exposure has been linked to impaired fetal growth and development. The effects of OP exposure on infants and children are at this time currently being researched to come to a conclusive finding. Evidence of OP exposure in pregnant mothers are linked to several health effects in the fetus. Some of these effects include delayed mental development, Pervasive developmental disorder (PDD), morphological abnormalities in the cerebral surface. Neurotoxic effects
Neurotoxic effects have also been linked to poisoning with OP pesticides causing four neurotoxic effects in humans: cholinergic syndrome, intermediate syndrome, organophosphate-induced delayed polyneuropathy (OPIDP), and chronic organophosphate-induced neuropsychiatric disorder (COPIND). These syndromes result after acute and chronic exposure to OP pesticides. Cholinergic syndrome occurs in acute poisonings with OP pesticides and is directly related to levels of AChE activity. Symptoms include miosis, sweating, lacrimation, gastrointestinal symptoms, respiratory difficulties, shortness of breath, slowed heart rate, cyanosis, vomiting, diarrhea, trouble sleeping, as well as other symptoms. Along with these central effects can be seen and finally seizures, convulsions, coma, respiratory failure. If the person survives the first day of poisoning, personality changes can occur, in addition to aggressive behavior, psychotic episodes, memory and attention disturbances, and other delayed effects.