Ethoprop

Ethoprophos (or ethoprop) is an organophosphate ester with the formula C8H19O2PS2. It is a clear yellow to colourless liquid that has a characteristic mercaptan-like odour. It is used as an insecticide and nematicide and it is an acetylcholinesterase inhibitor. Ethoprophos (or ethoprop) is an organophosphate ester with the formula C8H19O2PS2. It is a clear yellow to colourless liquid that has a characteristic mercaptan-like odour. It is used as an insecticide and nematicide and it is an acetylcholinesterase inhibitor. Ethoprop can be synthesised by reacting phosphoryl chloride with two equivalents of n-propylmercaptan and one equivalent of sodium ethoxide. A second pathway is reacting n-propylmercaptan and sodium ethoxide with phosphorus trichloride to yield ethoxy-bis(propylsulfanyl)phosphane, which can then be oxidized by hydrogen peroxide to yield the product. Ethoprop is used as an insecticide against soil insects like wireworms and as a nematicide. It is used on different crops, ranging from potatoes, bananas, and sugarcane to ornamental plants and tobacco. Most of the ethoprop used in the United States is applied to potatoes. In the period of 1987 to 1996, an estimated total of 691,000 pounds (313,400 kg) of the pesticide were used on field crops and vegetables. When an organism is exposed to ethoprophos either via the oral, dermal or inhalation routes, it primarily inhibits carboxyl ester hydrolases, specifically acetylcholinesterase (AChE). This enzyme is important in degradation of the neurotransmitter acetylcholine (ACh). Inactivation of AChE takes place by phosphorylation of serine hydroxyl group at the active site of AChE. Later, phosphorylation is followed by one of the following scenarios: When AChE is inactivated, ACh accumulates in the nervous system, which then results in overstimulation of muscarinic and nicotinic receptors. Another target of ethoprophos is erythrocyte acetylcholinesterase. The only known location of this enzyme is on the outside of erythrocyte membranes. However, physiological functions of this AChE type are not completely known. In cases of exposure to ethoprophos, symptoms may include vomiting, nausea, diarrhea, miosis, abdominal cramps, dyspnoea, muscular weakness, bronchial hypersecretion, anxiety, confusion and convulsions. In case of ethoprophos poisoning, a combination of atropine and pralidoxime (2-PAM) is the most effective antidote. Additionally, ethoprophos is thought to be likely carcinogenic due to the occurrence of different types of tumors in rats after exposure to the compound. Dietary exposure (the most common route of exposure to ethoprophos) is so low, however, that there is a low risk for the general U.S. population. In mammals, metabolism usually proceeds by removal of one or both of the propyl groups and subsequent conjugation. In rats, metabolism is independent of sex, dose, route of administration, or repeated administration, and no parent compound is detectable in faeces or urine. The main metabolite in humans is EPPA, shown below, which can be used as a biomarker for ethoprophos. The dealkylated metabolites have similar toxic effects to the parent compound.