Disulfoton is an

organophosphate In organic chemistry, organophosphates (also known as phosphate esters, or OPEs) are a class of organophosphorus compounds with the general structure , a central phosphate molecule with alkyl or aromatic substituents. They can be considered ...

acetylcholinesterase inhibitor Acetylcholinesterase inhibitors (AChEIs) also often called cholinesterase inhibitors, inhibit the enzyme acetylcholinesterase from breaking down the neurotransmitter acetylcholine into choline and acetate, thereby increasing both the level an ...

used as an

insecticide Insecticides are pesticides used to kill insects. They include ovicides and larvicides used against insect eggs and larvae, respectively. The major use of insecticides is in agriculture, but they are also used in home and garden settings, i ...

. It is manufactured under the name Di-Syston by

Bayer CropScience Bayer AG (English: , commonly pronounced ; ) is a German multinational pharmaceutical and biotechnology company and is one of the largest pharmaceutical companies and biomedical companies in the world. Headquartered in Leverkusen, Bayer's a ...

. Disulfoton in its pure form is a colorless oil but the technical product used in vegetable fields is dark and yellowish with a

sulfur Sulfur ( American spelling and the preferred IUPAC name) or sulphur ( Commonwealth spelling) is a chemical element; it has symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms ...

odor. Disulfoton is processed as a liquid into carrier granules. These granules are mixed with fertilizer and clay to be made into a spike, designed to be driven into the ground. The

pesticide Pesticides are substances that are used to control pests. They include herbicides, insecticides, nematicides, fungicides, and many others (see table). The most common of these are herbicides, which account for approximately 50% of all p ...

is absorbed over time by the roots and translocated to all parts of the plant. The pesticide acts as a

cholinesterase inhibitor Cholinesterase inhibitors (ChEIs), also known as anti-cholinesterase, are chemicals that prevent the breakdown of the neurotransmitter acetylcholine or butyrylcholine by cholinesterase. This increases the amount of the acetylcholine or butyryl ...

and gives long lasting control. The use of the substance has been restricted by the US government. Bayer, the manufacturer, exited the US market December 31, 2009.

Synthesis

Disulfoton is synthesized by sulfide formation of 2-ethylthioethanol + O,O-diethyl hydrogen phosphorodithioate with beta-chloroethyl thioethyl

ether In organic chemistry, ethers are a class of compounds that contain an ether group, a single oxygen atom bonded to two separate carbon atoms, each part of an organyl group (e.g., alkyl or aryl). They have the general formula , where R and R� ...

Metabolites

Oxidation of Disulfoton happens rapidly and metabolizes disulfoton into

sulfone In organic chemistry, a sulfone is a organosulfur compound containing a sulfonyl () functional group attached to two carbon atoms. The central hexavalent sulfur atom is double-bonded to each of two oxygen atoms and has a single bond to each of ...

s and

sulfoxide In organic chemistry, a sulfoxide, also called a sulphoxide, is an organosulfur compound containing a sulfinyl () functional group attached to two carbon atoms. It is a polar functional group. Sulfoxides are oxidized derivatives of sulfides. E ...

s, oxidation to oxygen analogs and/or

hydrolysis Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution reaction, substitution, elimination reaction, elimination, and solvation reactions in which water ...

to produce a corresponding phosphorothionate or phosphate. Microsomal enzymes are being inhibited during the metabolism.

Mechanism of action

Organophosphorus Organophosphorus chemistry is the scientific study of the synthesis and properties of organophosphorus compounds, which are organic compounds containing phosphorus. They are used primarily in pest control as an alternative to chlorinated hydrocarb ...

pesticides like Disulfoton inhibit esterase enzyme activity like choline esterase. These types of pesticides can also directly interact with the biochemical receptors of

acetylcholine Acetylcholine (ACh) is an organic compound that functions in the brain and body of many types of animals (including humans) as a neurotransmitter. Its name is derived from its chemical structure: it is an ester of acetic acid and choline. Par ...

. Organophosphates in general poisons mammals and insects by phosphorylating the acetylcholinesterase enzyme at nerve endings resulting in loss of function of the enzyme. This allows the accumulation of the neurotransmitter acetylcholine in

cholinergic Cholinergic agents are compounds which mimic the action of acetylcholine and/or butyrylcholine. In general, the word " choline" describes the various quaternary ammonium salts containing the ''N'',''N'',''N''-trimethylethanolammonium cation ...

neuroeffector junctions, skeletal myoneural junctions, and

autonomic ganglia An autonomic ganglion is a cluster of neuron, nerve cell Cell body, bodies (a ganglion) in the autonomic nervous system. The two types are the sympathetic ganglion and the parasympathetic ganglion. References

Autonomic ganglia, Auto ...

. This refers to the type of receptors of acetylcholine, the

muscarinic A muscarinic acetylcholine receptor agonist, also simply known as a muscarinic agonist or as a muscarinic agent, is an agent that activates the activity of the muscarinic acetylcholine receptor. The muscarinic receptor has different subtypes, lab ...

and nicotinic effects respectively. Thus organophosphates also impairs nerve impulse transmission. Disulfoton can be absorbed via ingestion, inhalation or penetration of the skin as it can be rapidly absorbed via

mucous membrane A mucous membrane or mucosa is a membrane that lines various cavities in the body of an organism and covers the surface of internal organs. It consists of one or more layers of epithelial cells overlying a layer of loose connective tissue. It ...

s. When disulfoton is absorbed, it will be distributed via the blood circulation and undergo hydrolytic degradation. This mainly happens in the liver or kidneys but in other tissues as well. Disulfoton is excreted in different

metabolite In biochemistry, a metabolite is an intermediate or end product of metabolism. The term is usually used for small molecules. Metabolites have various functions, including fuel, structure, signaling, stimulatory and inhibitory effects on enzymes, c ...

s via the urine.

Toxicity

Disulfoton is classified as a super toxic substance. The estimated oral

lethal dose In toxicology, the lethal dose (LD) is an indication of the lethal toxicity of a given substance or type of radiation. Because resistance varies from one individual to another, the "lethal dose" represents a dose (usually recorded as dose per kilog ...

in humans is less than 5 mg/kg, which is analog to seven drops for a 70 kg person. Not only oral intake, but also skin contact and inhalation are fatal because of acute toxicity. Disulfoton is also very toxic to aquatic life and forms an acute hazard with long lasting effects.

Symptoms

Signs of disulfoton toxicity includes headaches,

cyanosis Cyanosis is the change of Tissue (biology), tissue color to a bluish-purple hue, as a result of decrease in the amount of oxygen bound to the hemoglobin in the red blood cells of the capillary bed. Cyanosis is apparent usually in the Tissue (bi ...

, weakness, fatigue, nausea, vomiting, abdominal cramps, diarrhea, blurred vision, mental confusion, loss of muscle coordination and sialorrhea. Death can occur when respiratory arrest ensues from failure of the respiratory muscles. Other symptoms found in a patient with an unknown quantity of disulfoton were intra-alveolar bleeding, blood in the bronchus, edema of the lungs and swelling of the glomerulus.

Treatment

The treatment of the granular form of disulfoton poisoning should be with repetitive or prolonged gastric and intestinal lavage (washing out of the body cavity). Also charcoal and a continuous intravenous infusion of

pralidoxime Pralidoxime (2-pyridine aldoxime methyl chloride) or 2-PAM, usually as the chloride or iodide salts, belongs to a family of compounds called oximes that bind to organophosphate-inactivated acetylcholinesterase. It is used to treat organophosph ...

iodide An iodide ion is I−. Compounds with iodine in formal oxidation state −1 are called iodides. In everyday life, iodide is most commonly encountered as a component of iodized salt, which many governments mandate. Worldwide, iodine deficiency ...

in addition to atropine sulfate.

References

External links

Agency for Toxic Substances and Disease Registry The Agency for Toxic Substances and Disease Registry (ATSDR) is a federal public health agency within the U.S. Department of Health and Human Services (HHS). The agency focuses on minimizing human health risks associated with exposure to hazar ...

Disulfoton
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National Institute for Occupational Safety and Health The National Institute for Occupational Safety and Health (NIOSH, ) is the List of United States federal agencies, United States federal agency responsible for conducting research and making recommendations for the prevention of work-related occ ...

DisulfotonPubchemPubchem HSDB
{{Acetylcholine metabolism and transport modulators Acetylcholinesterase inhibitors Organophosphate insecticides Phosphorodithioates Ethyl esters