Organophosphorus Compounds: Organic compounds that contain phosphorus as an integral part of the molecule. Included under this heading is broad array of synthetic compounds that are used as PESTICIDES and DRUGS.Organophosphate Poisoning: Poisoning due to exposure to ORGANOPHOSPHORUS COMPOUNDS, such as ORGANOPHOSPHATES; ORGANOTHIOPHOSPHATES; and ORGANOTHIOPHOSPHONATES.Organothiophosphorus Compounds: Compounds containing carbon-phosphorus bonds in which the phosphorus component is also bonded to one or more sulfur atoms. Many of these compounds function as CHOLINERGIC AGENTS and as INSECTICIDES.Parathion: A highly toxic cholinesterase inhibitor that is used as an acaricide and as an insecticide.Malathion: A wide spectrum aliphatic organophosphate insecticide widely used for both domestic and commercial agricultural purposes.Pralidoxime Compounds: Various salts of a quaternary ammonium oxime that reconstitute inactivated acetylcholinesterase, especially at the neuromuscular junction, and may cause neuromuscular blockade. They are used as antidotes to organophosphorus poisoning as chlorides, iodides, methanesulfonates (mesylates), or other salts.Dichlorvos: An organophosphorus insecticide that inhibits ACETYLCHOLINESTERASE.Chemical Warfare Agents: Chemicals that are used to cause the disturbance, disease, or death of humans during WARFARE.Cholinesterase Inhibitors: Drugs that inhibit cholinesterases. The neurotransmitter ACETYLCHOLINE is rapidly hydrolyzed, and thereby inactivated, by cholinesterases. When cholinesterases are inhibited, the action of endogenously released acetylcholine at cholinergic synapses is potentiated. Cholinesterase inhibitors are widely used clinically for their potentiation of cholinergic inputs to the gastrointestinal tract and urinary bladder, the eye, and skeletal muscles; they are also used for their effects on the heart and the central nervous system.Paraoxon: An organophosphate cholinesterase inhibitor that is used as a pesticide.Insecticides: Pesticides designed to control insects that are harmful to man. The insects may be directly harmful, as those acting as disease vectors, or indirectly harmful, as destroyers of crops, food products, or textile fabrics.Soman: An organophosphorus compound that inhibits cholinesterase. It causes seizures and has been used as a chemical warfare agent.Cholinesterase Reactivators: Drugs used to reverse the inactivation of cholinesterase caused by organophosphates or sulfonates. They are an important component of therapy in agricultural, industrial, and military poisonings by organophosphates and sulfonates.Sarin: An organophosphorus ester compound that produces potent and irreversible inhibition of cholinesterase. It is toxic to the nervous system and is a chemical warfare agent.Trichlorfon: An organochlorophosphate cholinesterase inhibitor that is used as an insecticide for the control of flies and roaches. It is also used in anthelmintic compositions for animals. (From Merck, 11th ed)Tritolyl Phosphates: A mixture of isomeric tritolyl phosphates. Used in the sterilization of certain surgical instruments and in many industrial processes.Isoflurophate: A di-isopropyl-fluorophosphate which is an irreversible cholinesterase inhibitor used to investigate the NERVOUS SYSTEM.CholinesterasesAntidotes: Agents counteracting or neutralizing the action of POISONS.Acetylcholinesterase: An enzyme that catalyzes the hydrolysis of ACETYLCHOLINE to CHOLINE and acetate. In the CNS, this enzyme plays a role in the function of peripheral neuromuscular junctions. EC 18.104.22.168.Butyrylcholinesterase: An aspect of cholinesterase (EC 22.214.171.124).Chlorpyrifos: An organothiophosphate cholinesterase inhibitor that is used as an insecticide and as an acaricide.Phosphoric Triester Hydrolases: A class of enzymes that catalyze the hydrolysis of one of the three ester bonds in a phosphotriester-containing compound.Organophosphates: Carbon-containing phosphoric acid derivatives. Included under this heading are compounds that have CARBON atoms bound to one or more OXYGEN atoms of the P(=O)(O)3 structure. Note that several specific classes of endogenous phosphorus-containing compounds such as NUCLEOTIDES; PHOSPHOLIPIDS; and PHOSPHOPROTEINS are listed elsewhere.Houseflies: Flies of the species Musca domestica (family MUSCIDAE), which infest human habitations throughout the world and often act as carriers of pathogenic organisms.EsterasesPhosphoric Acids: Inorganic derivatives of phosphoric acid (H3PO4). Note that organic derivatives of phosphoric acids are listed under ORGANOPHOSPHATES.Leptophos: An organothiophosphate insecticide.Phenylphosphonothioic Acid, 2-Ethyl 2-(4-Nitrophenyl) Ester: An organothiophosphorus cholinesterase inhibitor that is used as an insecticide and as a acaricide.Decontamination: The removal of contaminating material, such as radioactive materials, biological materials, or CHEMICAL WARFARE AGENTS, from a person or object.Carbamates: Derivatives of carbamic acid, H2NC(=O)OH. Included under this heading are N-substituted and O-substituted carbamic acids. In general carbamate esters are referred to as urethanes, and polymers that include repeating units of carbamate are referred to as POLYURETHANES. Note however that polyurethanes are derived from the polymerization of ISOCYANATES and the singular term URETHANE refers to the ethyl ester of carbamic acid.Oximes: Compounds that contain the radical R2C=N.OH derived from condensation of ALDEHYDES or KETONES with HYDROXYLAMINE. Members of this group are CHOLINESTERASE REACTIVATORS.Pesticides: Chemicals used to destroy pests of any sort. The concept includes fungicides (FUNGICIDES, INDUSTRIAL); INSECTICIDES; RODENTICIDES; etc.Dimethoate: An organothiophosphorus cholinesterase inhibitor that is used as a systemic and contact insecticide.Methyl Parathion: The methyl homolog of parathion. An effective, but highly toxic, organothiophosphate insecticide and cholinesterase inhibitor.Organothiophosphates: Carbon-containing thiophosphoric acid derivatives. Included under this heading are compounds that have carbon bound to either SULFUR atom, or the OXYGEN atom of the SPO3 core structure.Diazinon: A cholinesterase inhibitor that is used as an organothiophosphorus insecticide.Insecticide Resistance: The development by insects of resistance to insecticides.Carboxylic Ester Hydrolases: Enzymes which catalyze the hydrolysis of carboxylic acid esters with the formation of an alcohol and a carboxylic acid anion.Chlorfenvinphos: An organophosphorus cholinesterase inhibitor that is used as an insecticide and an acaricide.Pesticide Residues: Pesticides or their breakdown products remaining in the environment following their normal use or accidental contamination.Aryldialkylphosphatase: An enzyme which catalyzes the hydrolysis of an aryl-dialkyl phosphate to form dialkyl phosphate and an aryl alcohol. It can hydrolyze a broad spectrum of organophosphate substrates and a number of aromatic carboxylic acid esters. It may also mediate an enzymatic protection of LOW DENSITY LIPOPROTEINS against oxidative modification and the consequent series of events leading to ATHEROMA formation. The enzyme was previously regarded to be identical with Arylesterase (EC 126.96.36.199).Chemistry: A basic science concerned with the composition, structure, and properties of matter; and the reactions that occur between substances and the associated energy exchange.Chemical Phenomena: The composition, conformation, and properties of atoms and molecules, and their reaction and interaction processes.Fenthion: Potent cholinesterase inhibitor used as an insecticide and acaricide.Poisoning: A condition or physical state produced by the ingestion, injection, inhalation of or exposure to a deleterious agent.Trimedoxime: Cholinesterase reactivator used as an antidote in alkyl phosphate poisoning.Sri LankaAzinphosmethyl: An organothiophosphorus cholinesterase inhibitor. It has been used as an acaricide and as an insecticide.Fenitrothion: An organothiophosphate cholinesterase inhibitor that is used as an insecticide.Carboxylesterase: Carboxylesterase is a serine-dependent esterase with wide substrate specificity. The enzyme is involved in the detoxification of XENOBIOTICS and the activation of ester and of amide PRODRUGS.Neurotoxicity Syndromes: Neurologic disorders caused by exposure to toxic substances through ingestion, injection, cutaneous application, or other method. This includes conditions caused by biologic, chemical, and pharmaceutical agents.Obidoxime Chloride: Cholinesterase reactivator occurring in two interchangeable isomeric forms, syn and anti.Lethal Dose 50: The dose amount of poisonous or toxic substance or dose of ionizing radiation required to kill 50% of the tested population.Agriculture: The science, art or practice of cultivating soil, producing crops, and raising livestock.Phosmet: An organothiophosphorus insecticide that has been used to control pig mange.Coumaphos: A organothiophosphorus cholinesterase inhibitor that is used as an anthelmintic, insecticide, and as a nematocide.Acetylthiocholine: An agent used as a substrate in assays for cholinesterases, especially to discriminate among enzyme types.Atropine: An alkaloid, originally from Atropa belladonna, but found in other plants, mainly SOLANACEAE. Hyoscyamine is the 3(S)-endo isomer of atropine.Health Food: A non-medical term defined by the lay public as a food that has little or no preservatives, which has not undergone major processing, enrichment or refinement and which may be grown without pesticides. (from Segen, The Dictionary of Modern Medicine, 1992)Environmental Monitoring: The monitoring of the level of toxins, chemical pollutants, microbial contaminants, or other harmful substances in the environment (soil, air, and water), workplace, or in the bodies of people and animals present in that environment.Environmental Exposure: The exposure to potentially harmful chemical, physical, or biological agents in the environment or to environmental factors that may include ionizing radiation, pathogenic organisms, or toxic chemicals.Carbaryl: A carbamate insecticide and parasiticide. It is a potent anticholinesterase agent belonging to the carbamate group of reversible cholinesterase inhibitors. It has a particularly low toxicity from dermal absorption and is used for control of head lice in some countries.Metaraminol: A sympathomimetic agent that acts predominantly at alpha-1 adrenergic receptors. It has been used primarily as a vasoconstrictor in the treatment of HYPOTENSION.Gastric Lavage: Medical procedure involving the emptying of contents in the stomach through the use of a tube inserted through the nose or mouth. It is performed to remove poisons or relieve pressure due to intestinal blockages or during surgery.Nerium: A plant genus of the family APOCYNACEAE. It is a very poisonous plant that contains cardioactive agents.Molecular Structure: The location of the atoms, groups or ions relative to one another in a molecule, as well as the number, type and location of covalent bonds.Chemical Terrorism: The use of chemical agents in TERRORISM. This includes the malevolent use of nerve agents, blood agents, blister agents, and choking agents (NOXAE).Dealkylation: The removing of alkyl groups from a compound. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 5th ed)Monoacylglycerol Lipases: An enzyme that catalyzes the hydrolysis of glycerol monoesters of long-chain fatty acids EC 188.8.131.52.Gas Chromatography-Mass Spectrometry: A microanalytical technique combining mass spectrometry and gas chromatography for the qualitative as well as quantitative determinations of compounds.Biodegradation, Environmental: Elimination of ENVIRONMENTAL POLLUTANTS; PESTICIDES and other waste using living organisms, usually involving intervention of environmental or sanitation engineers.EstersCresolsNitrophenolsSolid Phase Microextraction: A solventless sample preparation method, invented in 1989, that uses a fused silica fiber which is coated with a stationary phase. It is used for sample cleanup before using other analytical methods.Liquid Phase Microextraction: Miniaturized methods of liquid-liquid extraction.Enzymes, Immobilized: Enzymes which are immobilized on or in a variety of water-soluble or water-insoluble matrices with little or no loss of their catalytic activity. Since they can be reused continuously, immobilized enzymes have found wide application in the industrial, medical and research fields.Hydrolysis: The process of cleaving a chemical compound by the addition of a molecule of water.Culex: A genus of mosquitoes (CULICIDAE) commonly found in tropical regions. Species of this genus are vectors for ST. LOUIS ENCEPHALITIS as well as many other diseases of man and domestic and wild animals.Suicide, Attempted: The unsuccessful attempt to kill oneself.Chromatography, Gas: Fractionation of a vaporized sample as a consequence of partition between a mobile gaseous phase and a stationary phase held in a column. Two types are gas-solid chromatography, where the fixed phase is a solid, and gas-liquid, in which the stationary phase is a nonvolatile liquid supported on an inert solid matrix.Kinetics: The rate dynamics in chemical or physical systems.Charcoal: An amorphous form of carbon prepared from the incomplete combustion of animal or vegetable matter, e.g., wood. The activated form of charcoal is used in the treatment of poisoning. (Grant & Hackh's Chemical Dictionary, 5th ed)Structure-Activity Relationship: The relationship between the chemical structure of a compound and its biological or pharmacological activity. Compounds are often classed together because they have structural characteristics in common including shape, size, stereochemical arrangement, and distribution of functional groups.Dose-Response Relationship, Drug: The relationship between the dose of an administered drug and the response of the organism to the drug.Brain: The part of CENTRAL NERVOUS SYSTEM that is contained within the skull (CRANIUM). Arising from the NEURAL TUBE, the embryonic brain is comprised of three major parts including PROSENCEPHALON (the forebrain); MESENCEPHALON (the midbrain); and RHOMBENCEPHALON (the hindbrain). The developed brain consists of CEREBRUM; CEREBELLUM; and other structures in the BRAIN STEM.Agricultural Workers' Diseases: Diseases in persons engaged in cultivating and tilling soil, growing plants, harvesting crops, raising livestock, or otherwise engaged in husbandry and farming. The diseases are not restricted to farmers in the sense of those who perform conventional farm chores: the heading applies also to those engaged in the individual activities named above, as in those only gathering harvest or in those only dusting crops.Nervous System Diseases: Diseases of the central and peripheral nervous system. This includes disorders of the brain, spinal cord, cranial nerves, peripheral nerves, nerve roots, autonomic nervous system, neuromuscular junction, and muscle.Biotin: A water-soluble, enzyme co-factor present in minute amounts in every living cell. It occurs mainly bound to proteins or polypeptides and is abundant in liver, kidney, pancreas, yeast, and milk.Insects: The class Insecta, in the phylum ARTHROPODA, whose members are characterized by division into three parts: head, thorax, and abdomen. They are the dominant group of animals on earth; several hundred thousand different kinds having been described. Three orders, HEMIPTERA; DIPTERA; and SIPHONAPTERA; are of medical interest in that they cause disease in humans and animals. (From Borror et al., An Introduction to the Study of Insects, 4th ed, p1)Muscarinic Antagonists: Drugs that bind to but do not activate MUSCARINIC RECEPTORS, thereby blocking the actions of endogenous ACETYLCHOLINE or exogenous agonists. Muscarinic antagonists have widespread effects including actions on the iris and ciliary muscle of the eye, the heart and blood vessels, secretions of the respiratory tract, GI system, and salivary glands, GI motility, urinary bladder tone, and the central nervous system.Solid Phase Extraction: An extraction method that separates analytes using a solid phase and a liquid phase. It is used for preparative sample cleanup before analysis by CHROMATOGRAPHY and other analytical methods.Sulfur Compounds: Inorganic or organic compounds that contain sulfur as an integral part of the molecule.Chromatography, High Pressure Liquid: Liquid chromatographic techniques which feature high inlet pressures, high sensitivity, and high speed.Volatile Organic Compounds: Organic compounds that have a relatively high VAPOR PRESSURE at room temperature.Food Contamination: The presence in food of harmful, unpalatable, or otherwise objectionable foreign substances, e.g. chemicals, microorganisms or diluents, before, during, or after processing or storage.Occupational Exposure: The exposure to potentially harmful chemical, physical, or biological agents that occurs as a result of one's occupation.