Omethoate

213.19

213.19

214-197-8

28U28EWE79

DTXSID4037580

Colorless liquid|Colorless to yellowish oily liquid

2930909063

99.74000

-0.74

Colorless liquid. Mercaptan-like odor.

1.32 g/cm³

-28 °C

150-152 °C @ Press: 0.1-0.2 Torr

100 °C

1.474

Readily soluble in water.

0-6°C

2.48X10-5 mm Hg at 20 deg C

Oral-rat LD50: 30 mg/kg; Abdominal cavity-mouse LD50: 24 mg/kg

Open flame is flammable; heat releases toxic phosphorus oxide, nitrogen oxide, sulfur oxide gas

Mercaptan-like odor

Henry's Law constant = 4.56X10-14 atm-cu m/mol at 25 °C (est)

134.62 Ų [M+H]+ [CCS Type: TW]|135.08 Ų [M+H]+

Hydroxyl radical reaction rate constant = 2.60X10-11 cu cm/molec-sec at 25 °C (est)

Non-corrosive

II

6.1(a)

3018

21-25-50

1/2-23-36/37-45-61

TF8050000

T+;N,N,T+,T

The warehouse is ventilated, low temperature and dry; stored and transported separately from food materials

Hydrolyzed in alkaline media; relatively slowly hydrolyzed in acidic media.

P264-P273-P280-P301 + P310-P312

H300-H311-H400

SRP: The most favorable course of action is to use an alternative chemical product with less inherent propensity for occupational exposure or environmental contamination. Recycle any unused portion of the material for its approved use or return it to the manufacturer or supplier. Ultimate disposal of the chemical must consider: the material's impact on air quality; potential migration in soil or water; effects on animal, aquatic, and plant life; and conformance with environmental and public health regulations.|All organic pesticides, whether of botanical or synthetic origin, can be destroyed by incineration. /Organic pesticides/|Manufacturers or formulators of very large amounts of pesticides may find it advantageous to build incinerators adequate to destroy all organic pesticides and equipped with scrubbers to remove acid wastes. /Organic pesticides/

... Incompatible with alkaline materials.

FAO/WHO; Pesticide Residues in Food: 1996 Evaluations Part II Toxicological- Dimethoate (1996). Available from: http://www.inchem.org/documents/jmpr/jmpmono/v96pr05.htm as of March 5, 2007. Dimethoate was evaluated for toxicological effects by the Joint Meeting in 1963, 1965, 1967, 1984, and 1987and 1996. Omethoate is the oxygen analogue of dimethoate. It was used previously as a pesticide in its own right. Information was available to indicate that omethoate will no longer be used in this fashion; however, since use of dimethoate on agricultural crops can lead to residues of omethoate in treated produce, it is important to consider the toxicity of omethoate when evaluating potential use of dimethoate.|USEPA/Office of Pesticide Programs; Interim Reregistration Eligibility Decision for Dimethoate p.73. EPA-HQ-OPP-2005-0084 (July 2006) This report describes omethoate(O,O-dimethyl S-(Nmethylcarbamoylmethyl) phosphorothioate) as the major toxic degradate of dimethoate and notes that omethoate is registered as an active ingredient internationally, but not in the United States.[Available from, as of February 15, 2007. http://www.epa.gov/pesticides/reregistration/status.htm]

|Danger|H301: Toxic if swallowed [Danger Acute toxicity, oral]|P264, P270, P273, P280, P301+P310, P302+P352, P312, P321, P322, P330, P363, P391, P405, and P501|H300 (92.68%): Fatal if swallowed [Danger Acute toxicity, oral]|P264, P270, P273, P280, P301+P310, P302+P352, P312, P321, P322, P330, P361, P363, P391, P405, and P501|Aggregated GHS information provided by 41 companies from 2 notifications to the ECHA C&L Inventory. Each notification may be associated with multiple companies.

Respiratory protection (supplied-air respirator with full facepiece or self-contained breathing apparatus) should be available where these compounds are manufactured or used and should be worn in case of emergency and overexposure. /Phosphorus compounds/|Workers handling and applying organophosphate pesticides (opp) must ... Be given personal protective equipment comprising overalls made of a tight fabric or polyvinyl chloride, gloves, and rubber boots. They must wear a respirator with an activated-carbon gas filter cartridge affording protection for a determined number of working hours. The eyes should be protected by goggles. The signalmen for aerial dusting operations should be equipped with a hat and cape made of polyvinyl chloride or a fabric impregnated with a water repellent. /Pesticides, organophosphorus/|Personnel protection ... Wear appropriate chemical protective gloves, boots and goggles. ... Wear positive pressure self-contained breathing apparatus when fighting fires involving this material. /Organophosphorus pesticides, liquid, flammable, toxic/|Personnel protection: ... Wear positive pressure self-contained breathing apparatus. ... Wear appropriate chemical protective clothing. /Organophosphorus pesticides, liquid and solid, NOS/

If material on fire or involved in fire: Do not extinguish fire unless flow can be stopped or safely confined. Use water in flooding quantities as fog. Solid streams of water may be ineffective. Cool all affected containers with flooding quantities of water. Apply water from as far a distance as possible. Use "alcohol" foam, carbon dioxide or dry chemical. /Organophosphorus pesticides, liquid, NOS/|If material on fire or involved in fire: Use water in flooding quantities as fog. Extinguish fire using agent suitable for type of surrounding fire. (Material itself does not burn or burns with difficulty.) Use "alcohol" foam, carbon dioxide or dry chemical. /Organophosphorus pesticides, solid, NOS/

Environmental considerations- land spill: Dig a pit, pond, lagoon, holding area to contain liquid or solid material. /SRP: If time permits, pits, ponds, lagoons, soak holes, or holding areas should be sealed with an impermeable flexible membrane liner./ Dike surface flow using soil, sand bags, foamed polyurethane, or foamed concrete. Absorb bulk liquid with fly ash, cement powder, or commercial sorbents. /Organophosphorus pesticides, liquid and solid, NOS/|Environmental considerations- water spill: Use natural barriers or oil spill control booms to limit spill travel. Remove trapped material with suction hoses. /Organophosphorus pesticides, liquid and solid, NOS/|Environmental considerations- air spill: Apply water spray or mist to knock down vapors. /Organophosphorus pesticides, liquid and solid, NOS/

SRP: The scientific literature for the use of contact lenses in industry is conflicting. The benefit or detrimental effects of wearing contact lenses depend not only upon the substance, but also on factors including the form of the substance, characteristics and duration of the exposure, the uses of other eye protection equipment, and the hygiene of the lenses. However, there may be individual substances whose irritating or corrosive properties are such that the wearing of contact lenses would be harmful to the eye. In those specific cases, contact lenses should not be worn. In any event, the usual eye protection equipment should be worn even when contact lenses are in place.|In some situations where personnel may become accidently contaminated ... it is necessary to provide shower bath in addition to the usual washing facilities. Special arrangements for cleaning clothing & overalls may be necessary ... /Pesticides/|Special aircraft should preferably be used for spraying or dusting toxic organophosphorus pesticides. ... aerial spraying or dusting gives rise to clouds which spread over larger surfaces than clouds produced by ground application. Aerial spraying should therefore be carried out on windless days only. Residential areas, water supply sources, etc must be avoided. ... When aircraft approaches, signalmen /guiding the aircraft/ should leave the windward side. ... The local population should be informed about the site & time of aerial pesticide treatment. Access of unauthorized persons & especially children to the area to be treated must be ... forbidden. Warning signs should be placed at the limits of the area. Ground spraying must be carried out with compressed-air spraying equipment towed by tractors with closed cabs. /Organophosphorus pesticides/|Small packages of pesticides are preferable for individual application in order to limit the quantities to be weighed & metered. A special vessel with long stirring rod for dilution & suspension of the poison must be available in order to reduce manual handling to a minimum. The strict observance of hygiene rules--no smoking & no food intake during work. Thorough washing with soap after work, changing protective clothing before going home--is of utmost importance. /Organophosphorus pesticides/|For more Preventive Measures (Complete) data for OMETHOATE (14 total), please visit the HSDB record page.

/GUIDE 131: FLAMMABLE LIQUIDS-TOXIC/ Health: TOXIC; may be fatal if inhaled, ingested or absorbed through skin. Inhalation or contact with some of these materials will irritate or burn skin and eyes. Fire will produce irritating, corrosive and/or toxic gases. Vapors may cause dizziness or suffocation. Runoff from fire control or dilution water may cause pollution. /Organophosphorus pesticide, liquid, flammable, poisonous; Organophosphorus pesticide, liquid, flammable, toxic; Organophosphorus pesticide, liquid, poisonous, flammable; Organophosphorus pesticide, liquid, toxic, flammable/|/GUIDE 131: FLAMMABLE LIQUIDS-TOXIC/ Fire or Explosion: HIGHLY FLAMMABLE: Will be easily ignited by heat, sparks or flames. Vapors may form explosive mixtures with air. Vapors may travel to source of ignition and flash back. Most vapors are heavier than air. They will spread along ground and collect in low or confined areas (sewers, basements, tanks). Vapor explosion and poison hazard indoors, outdoors or in sewers. Those substances designated with a "P" may polymerize explosively when heated or involved in a fire. Runoff to sewer may create fire or explosion hazard. Containers may explode when heated. Many liquids are lighter than water. /Organophosphorus pesticide, liquid, flammable, poisonous; Organophosphorus pesticide, liquid, flammable, toxic; Organophosphorus pesticide, liquid, poisonous, flammable; Organophosphorus pesticide, liquid, toxic, flammable/|/GUIDE 131: FLAMMABLE LIQUIDS-TOXIC/ Public Safety: CALL Emergency Response Telephone Number ... . As an immediate precautionary measure, isolate spill or leak area for at least 50 meters (150 feet) in all directions. Keep unauthorized personnel away. Stay upwind. Keep out of low areas. Ventilate closed spaces before entering. /Organophosphorus pesticide, liquid, flammable, poisonous; Organophosphorus pesticide, liquid, flammable, toxic; Organophosphorus pesticide, liquid, poisonous, flammable; Organophosphorus pesticide, liquid, toxic, flammable/|/GUIDE 131: FLAMMABLE LIQUIDS-TOXIC/ Protective Clothing: Wear positive pressure self-contained breathing apparatus (SCBA). Wear chemical protective clothing that is specifically recommended by the manufacturer. It may provide little or no thermal protection. Structural firefighters' protective clothing provides limited protection in fire situations ONLY; it is not effective in spill situations where direct contact with the substance is possible. /Organophosphorus pesticide, liquid, flammable, poisonous; Organophosphorus pesticide, liquid, flammable, toxic; Organophosphorus pesticide, liquid, poisonous, flammable; Organophosphorus pesticide, liquid, toxic, flammable/|For more DOT Emergency Guidelines (Complete) data for OMETHOATE (16 total), please visit the HSDB record page.

No person may /transport,/ offer or accept a hazardous material for transportation in commerce unless that person is registered in conformance ... and the hazardous material is properly classed, described, packaged, marked, labeled, and in condition for shipment as required or authorized by ... /the hazardous materials regulations (49 CFR 171-177)./|The International Air Transport Association (IATA) Dangerous Goods Regulations are published by the IATA Dangerous Goods Board pursuant to IATA Resolutions 618 and 619 and constitute a manual of industry carrier regulations to be followed by all IATA Member airlines when transporting hazardous materials.|The International Maritime Dangerous Goods Code lays down basic principles for transporting hazardous chemicals. Detailed recommendations for individual substances and a number of recommendations for good practice are included in the classes dealing with such substances. A general index of technical names has also been compiled. This index should always be consulted when attempting to locate the appropriate procedures to be used when shipping any substance or article.

SEDIMENT: Sediment concentrations of omethoate were reported as 0.11-1.42 ng/g in the Wuchuan River region of China(1).|SOIL: Soil concentrations of omethoate were reported as 0.15-1.59 ng/g in the Wuchuan River region of China(1).

most toxic

Anticholinesterase (organophosphorus) insecticides antagonize polarizing muscle relaxants. Phenothiazines /and thioxanthenes/: ... May enhance toxic effects of organophosphorus insecticides. /Insecticides, organophosphorus/|In long term therapy, adrenocorticoids antagonize the antiglaucoma effects of anticholinesterases (incr ocular pressure). ... Anticholinergics antagonize the miotic (antiglaucoma) & other muscarinic effects of anticholinesterases on the autonomic & central nervous systems. Tricyclic antidepressants (anticholinergic effects) antagonize the antiglaucoma (miotic) effects of anticholinesterases in glaucoma. ... Antihistamines with anticholinergic effects antagonize the miotic (antiglaucoma) & CNS effects of anticholinesterases. Anticholinesterases potentiate tranquilizing & behavioral changes induced by antihistamines. The actions of anticholinesterase agents on autonomic effector cells, & to some extent those on CNS, are antagonized by atropine, an antidote of choice. Barbiturates are potentiated by anticholinesterases. ... Dexpanthenol potentiates the effects of anticholinesterases. Fluorophosphate insecticides potentiate the effects of other anticholinesterases. /Anticholinesterases/|...To examine the therapeutic effect of combined use of obidoxime and atropine with artificial ventilation on respiratory muscle paralysis caused by omethoate poisoning... rats were exposed to 2 times the dose of LD50 omethoate and treated with atropine (10 mg/kg) to counteract cholinergic symptoms. When the rats' respiratory frequency became slower and /breathing labored/, trachea intubation and artificial ventilation was carried out. The rats in group A were continuously treated with atropine. The dose of obidoxime for Group B, C and D were 8, 15, 20 mg/kg respectively, given at the same time as artificial ventilation and 1, 2, 3 hours later. The doses of atropine was reduced to 1/3 - 2/3 of the first dose so as to maintain the rats atropinized. If the rat survival was beyond 60 minutes after withdrawal of artificial ventilation, the combined treatment was considered successful. The function of isolated phrenic diaphragm of the rats was observed with MS-302 physiological and pharmacological analysis instrument. None of the rats in Group A was successful after withdrawal from artificial ventilation and the function of phrenic diaphragm appeared poor; whereas >80% of the rats in B, C, D Group were successful after withdrawal from artificial ventilation in 3 hr and the function of phrenic diaphragm remained well. The survival rate in B, C and D groups were higher after withdrawal from artificial ventilation than that in Group A(P<0.01). The function of phrenic diaphragm in Group B, C and D were gradually decreased after ACh was added into the container. /The authors concluded that/ combined use of suitable dose of obidoxime and atropine with artificial ventilation for respiratory muscle paralysis caused by omethoate poisoning could promote the recovery of diaphragm function and reduce the death rate in poisoned rats.|Barbiturates are potentiated by anticholinesterases. Although barbiturates may be used cautiously in treating convulsions, extreme care is essential in handling poisonings due to anticholinesterases, particularly organophosphorus pesticides. Echothiophate, a cholinesterase inhibitor used as miotic, potentiates other such inhibitors ... Used for other purposes (additive effects) or possibly synergistic. Those exposed to organophosphate insecticides must take strict precautions. ... Organophosphorus insecticides: additive anticholinesterase effects. Hazardous. Patients on anticholinesterases (even topical, such as eye drops) should avoid areas where organophosphorus insecticides ...recently ...used. /Anticholinesterase/

LD50 Rat oral 25 mg/kg|LD50 Rabbit oral 50 mg/kg|LD50 Cat oral 50 mg/kg|LD50 Guinea pig oral 100 mg/kg|For more Non-Human Toxicity Values (Complete) data for OMETHOATE (10 total), please visit the HSDB record page.

/AQUATIC SPECIES/ The acute toxicities of two organophosphorodithioate (dimethoate and disulfoton) and two organophosphorothioate (omethoate and demeton-S-methyl) insecticides were evaluated individually and in binary combination with the herbicide atrazine using fourth-instar larvae of the aquatic midge, Chironomus tentans. Atrazine alone up to 1,000 ug/L did not show significant toxicity to the midges in a 48-hr bioassay. However, atrazine concentrations as low as 1 ug/L in combination with dimethoate at EC25 (concentration to affect 25% of tested midges), 100 ug/L in combination with disulfoton (EC25), and 10 ug/L in combination with demeton-S-methyl (EC25) significantly enhanced the toxicity of each organophosphate insecticide. In contrast, atrazine concentrations of 10 ug/L and above in combination with omethoate (EC25) significantly decreased the toxicity of the insecticide. Biochemical analysis indicated that increased toxicity of dimethoate, disulfoton, and demeton-S-methyl in binary combination with atrazine correlated to the increased inhibition of acetylcholinesterase. Furthermore, cytochrome P450-dependent O-deethylation activity in the midges exposed to atrazine at 1,000 ug/L was 1.5-fold higher than that in the control midges. Thus, atrazine appeared to induce cytochrome P450 monooxygenases in the midges. Elevated cytochrome P450 monooxygenase activity may increase the toxicities of dimethoate, disulfoton, and demeton-S-methyl by enhancing the oxidative activation of dimethoate into omethoate, and disulfoton and demeton-S-methyl into their sulfoxide analogs with increased anticholinesterase activity. In contrast, atrazine reduced the toxicity of omethoate possibly by enhancing the oxidative metabolic detoxification since omethoate does not require oxidative activation.|/OTHER TERRESTRIAL SPECIES/ The actions on the honeybees of the insecticide-acaricides azinphos-methyl and omethoate, the insecticide diazinon, were investigated by ingestion and indirect contact in laboratory tests. The results of the trials revealed that the organophosphates azinphos-methyl, omethoate, and diazinon were highly toxic by ingestion and contact. Due to their high toxicity even at doses many times lower than those suggested for crop treatments, the organophosphorus compounds azinphos-methyl, omethoate, diazinon, and the heterocyclic dicarbonitrile dithianon appeared very dangerous to foraging and pollinating honeybees.

Young persons under 18 yr, expectant or nursing mothers, /alcoholics/, or persons for whom work with toxic chemicals is contraindicated on account of their state of health /are at elevated risk from the toxic effects of organophosphorus pesticides. Those individuals with/ organic diseases of the CNS, mental disorders & epilepsy, pronounced endocrine & vegetative disorders, pulmonary tuberculosis, bronchial asthma, chronic respiratory diseases, cardiovascular diseases and circulatory disorders, gastrointestinal diseases (peptic ulcer), gastroenterocolitis, diseases of the liver & kidneys, eye diseases (chronic conjunctivitis and keratitis) /are at elevated risk from exposure/. /Organophosphorus pesticides/|Those individuals who are exposed to organophosphorus pesticides with pre-existing/ organic diseases of the central nervous system, mental disorders & epilepsy, pronounced endocrine & vegetative disorders, pulmonary tuberculosis, bronchial asthma, chronic respiratory diseases, cardiovascular diseases & circulatory disorders, gastrointestinal diseases (peptic ulcer), gastroenterocolitis, diseases of liver & kidneys, eye diseases (chronic conjunctivitis & keratitis) /are at elevated risk from exposure/. The blood cholinesterase activity must be determined before work starts. In the event of prolonged work periods, this activity should be determined at intervals of 3-4 days. Persons exhibiting a fall in cholinesterase activity of 25% or more must be transferred to other work where they are not exposed to organophosphorus pesticides until this activity is completely restored. Persons with initial signs of indisposition should cease work with pesticides. /Organophosphorus pesticides/

Omethoate's former US production may have resulted in its release to the environment through various waste streams; it's use as a insecticide(1) will result in its direct release to the environment(SRC). Omethoate is registered as an active ingredient internationally, but not in the United States(2). Omethoate may also be released to the environment during the production and use of dimethoate as it is a metabolite of dimethoate(1).

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 9.4(SRC), determined from a log Kow of -0.74(2) and a regression-derived equation(3), indicates that omethoate is expected to have very high mobility in soil(SRC). Volatilization of omethoate from moist soil surfaces is not expected to be an important fate process(SRC) given an estimated Henry's Law constant of 4.6X10-14 atm-cu m/mole(SRC), using a fragment constant estimation method(4). Omethoate is not expected to volatilize from dry soil surfaces(SRC) based upon a vapor pressure of 2.48X10-5 mm Hg(2). Biodegradation in soil may be an important fate process in soil based on rapid rates for analogous dimethoate(SRC); dimethoate exhibited 77% degradation in clay loam soil in 2 wks compared to 18 and 20% degradation in the same soil that had been autoclaved or irradiated(5).|AQUATIC FATE: Based on a classification scheme(1), an estimated Koc value of 9.4(SRC), determined from a log Kow of -0.74(2) and a regression-derived equation(3), indicates that omethoate is not expected to adsorb to suspended solids and sediment(SRC). Volatilization from water surfaces is not expected(3) based upon an estimated Henry's Law constant of 4.6X10-14 atm-cu m/mole(SRC), developed using a fragment constant estimation method(4). Omethoate undergoes 50% decomposition in 26 days by hydrolysis in water at 24 °C and pH 7(5). According to a classification scheme(6), an estimated BCF of 3(SRC), from its log Kow(2) and a regression-derived equation(7), suggests the potential for bioconcentration in aquatic organisms is low(SRC). By analogy to dimethoate, which exhibited half-lives of 171, 173 and 219 days for river water, filtered river water and sea water, respectively(8), biodegradation of omethoate in water may be an important environmental fate process(SRC).|ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), omethoate, which has a vapor pressure of 2.48X10-5 mm Hg at 20 °C(2), will exist in both the vapor and particulate phases in the ambient atmosphere. Vapor-phase omethoate is degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals(SRC); the half-life for this reaction in air is estimated to be 15 hours(SRC), calculated from its rate constant of 2.6X10-11 cu cm/molecule-sec at 25 °C(SRC) that was derived using a structure estimation method(3). Particulate-phase omethoate may be removed from the air by wet or dry deposition(SRC).

The rate constant for the vapor-phase reaction of omethoate with photochemically-produced hydroxyl radicals has been estimated as 2.6X10-11 cu cm/molecule-sec at 25 °C(SRC) using a structure estimation method(1). This corresponds to an atmospheric half-life of about 15 hours at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm(1). Omethoate is hydrolyzed more rapidly in alkaline media than acidic media - DT50 (estimated): 102 days (pH 4), 17 days (pH 7), 28 hours (pH 9) 22 °C(2). Omethoate undergoes 50% decomposition in 26 days by hydrolysis in water at 24 °C and pH 7(3). Omethoate is rapidly taken up by plants(2). Demethylation and hydrolysis of P-S bonds are the main metabolic steps(2). Main metabolites are 3-hydroxy-3-(2-methylamino-2-oxo-ethyl)thioproprionic acid and its oxidation products(2).

An estimated BCF of 3 was calculated in fish for omethoate(SRC), using a log Kow of -0.74(1) and a regression-derived equation(2). According to a classification scheme(3), this BCF suggests the potential for bioconcentration in aquatic organisms is low(SRC).

The Koc of omethoate is estimated as 9.4(SRC), using a log Kow of -0.74(1) and a regression-derived equation(2). According to a classification scheme(3), this estimated Koc value suggests that omethoate is expected to have very high mobility in soil(SRC). Aged leaching studies revealed that metabolites have only a low leaching potential(1).

The Henry's Law constant for omethoate is estimated as 4.6X10-14 atm-cu m/mole(SRC) using a fragment constant estimation method(1). This Henry's Law constant indicates that omethoate is expected to be essentially nonvolatile from water surfaces(2). Omethoate is not expected to volatilize from dry soil surfaces(SRC) based upon a vapor pressure of 2.48X10-5 mm Hg(3).

SURFACE WATER: River water sample concentrations were reported as 9.68-35.54 ng/L from the Wuchuan River in China(1).

The Food and Drug Administration's (FDA) Los Angeles District Laboratory analyzed 6,391 domestic agricultural commodities during surveillance sampling for the period 10/81 to 9/86(1). The percentage of domestic commodities with omethoate concentrations in the 0.05, 0.1, 0.5, 1.0, and 2.0 ppm ranges were 3.7, 1.2, 1.4, 0.06, and 0.03%, respectively(1). The Food and Drug Administration's (FDA) Los Angeles District Laboratory analyzed 12,044 imported agricultural commodities during surveillance sampling for the period 10/81 to 9/86(1). The percentage of imported commodities with omethoate concentrations in the 0.05, 0.1, 0.5, 1.0, 2.0, and >2.0 ppm ranges were 1.6, 0.9, 1.2, 0.1, 0.06 and 0.04%, respectively(1). Omethoate was not detected in canned peaches from the 1999 season or fresh peaches form 8/2000 in 210 samples from Imathia and Pella, Greece(2). In a 1995 monitoring program in Egypt omethoate was not detected in cauliflower, carrot, courgette, cucumber, eggplant, cantaloupe, guava, mango, orange, or strawberry(3). Omethoate was found in cabbage, green beans, green peas, lettuce, tomato, apple grape and peach in the same 1995 monitoring program(3). In a 1996 monitoring program in Egypt omethoate was not detected in cabbage, melokhia, lettuce, watercress, artichoke, board bean, cauliflower, cantaloupe, cucumber, okra, onion, pepper, squash, tomato, carrot, sweet potato, taro, apple, apricot, mango, orange, pear, plum, pomegranate or strawberry(4). Omethoate was found in grape leaf, spinach, eggplant, green bean, green pea and peach in the same 1996 monitoring program(4). Omethoate was not detected in grapefruit, lemon, mandarin/clementine, orange, apple, pear, apricot, cherries, peach, nectarine, plum, grape, strawberry, blackberry, boysenberry, elderberry, raspberry, rowanberry, bilberry, red current, black current, gooseberry, banana, fig, pomegranate, beetroot, carrot, celeriac, horseradish, parsnip, parsley root, radish, garlic, onion, spring onion, tomato, pepper, eggplant, cucumber, melon, watermelon, squash, sweet corn, broccoli, cauliflower, brussels sprout, white cabbage, red cabbage, spring cabbage, oxheart cabbage, Chinese cabbage, kale, lettuce, spinach, chive, dill, marjoram, oregano, parsley, rosemary, thyme, bean, pea, celery, leek, rhubarb, mushroom, sunflower seed, or potato in the 1995-1996 Danish national pesticide monitoring program(5).

Many of the organophosphorus insecticides are excreted in the milk ... . /Organophosphorus insecticides/

Occupational exposure to omethoate may have occured through inhalation and dermal contact with this compound at US workplaces where omethoate was produced or used. Monitoring data indicate that the general population may be exposed to omethoate via ingestion of food and contaminated drinking water. (SRC)

Most organophosphate compounds are ... absorbed from skin, conjunctiva, gastrointestinal tract, & lung. /Organophosphate compounds/|The rate of dermal absorption /of organophosphorus pesticides/ may be ... influenced by the solvent used. /Organophosphorus pesticides/|... The organophosphorus insecticides are, in contrast to the chlorinated insecticides, rapidly metabolized & excreted and are not appreciably stored in body tissues. /Organophosphorus insecticides/|Many of the organophosphorus insecticides are excreted in the milk ... . /Organophosphorus insecticides/|For more Absorption, Distribution and Excretion (Complete) data for OMETHOATE (10 total), please visit the HSDB record page.

Plasma & tissue esterases are responsible for hydrolysis /of organophosphorus compounds/ to the corresponding phosphoric & phosphonic acids. However, oxidative enzymes are also involved in the metabolism of some organophosphorus compounds. /Anticholinesterase agents/|The organophosphorus anticholinesterase agents are hydrolyzed in the body by a group of enzymes known as A-esterases or paraoxonases. These enzymes are found in the plasma and liver & hydrolyze a large number of organophosphorus compounds ... by cleaving the phosphoester, anhydride, P-F, P-CN bonds. /Anticholinesterase agents/|These chemicals are detoxified by cytochrome p450 mediated monooxygenases in the liver, but some metabolites are more toxic than parent cmpd ... Metabolites usually are detected from 12 to 48 hr postexposure. /Organophosphate cmpd/|Urine was collected from two male rats 12, 24, and 48 hr after an oral dose of 50 mg/kg bw radiolabelled omethoate. The cumulative percentages of administered radiolabel excreted over the indicated times were 16, 19, and 30%. The metabolites found in a 24-hr composite urine sample by ion-exchange chromatography were: O,O-dimethylphosphoric acid (34%), unknown A (52%), O,O-dimethylphosphorothioic acid (9.5%), and unknown B (4.5%). ...In the /study on on pulmonary excretion/..., the predominant form of excreted radiolabel was unchanged parent compound (26-62%), with N-methyl-2-(methylsulfinyl)acetamide accounting for 16-36% and an O-demethylated omethoate for 4-9%. Pretreatment of animals for 14 days with unlabelled omethoate followed by a single labelled dose resulted in no significant difference from the results obtained after a single administration.|Dealkylation of omethoate was proposed to be a significant detoxification mechanism on the basis of information from assays in fly heads. Oxidative metabolism of omethoate results in the de-N-methyl derivative, which is as toxic as the parent compound although less active as a cholinesterase inhibitor. Kinetic studies indicated that the reaction between acetylcholinesterase and omethoate was irreversible and bimolecular. Omethoate was 75-100 times more potent than dimethoate in inhibiting rat brain acetylcholinesterase activity.|Omethoate is a known human metabolite of Dimethoate.

Organophosphorus derivatives act by combining with and inactivating the enzyme acetylcholinesterase (AChE). ... The inactivation of cholinesterase by cholinesterase inhibitor pesticides allows the accumulation of large amounts of acetylcholine, with resultant widespread effects that may be ... separated into 4 categories: (1) Potentiation of postganglionic parasympathetic activity. ... (2) Persistent depolarization of skeletal muscle ... (3) Initial stimulation following depression of cells of central nervous system ... (4) Variable ganglionic stimulation or blockade ... /Cholinesterase inhibitor pesticides/|The main feature of the toxic mechanism of organophosphorus pesticides is inhibition of the esterase enzyme activity, in particular of cholinesterase, which plays an important physiological part. Organophosphorus pesticides can also indirectly interact with the biochemical receptors of acetylcholine. /Organophosphorus pesticides/|Systemic insecticide and acaricide with contact and stomach action. Cholinesterase inhibitor.|Organophosphates poison insects and humans primarily by phosphorylation of the acetylcholinesterase enzyme at nerve endings. /Organophosphate Cholinesterase-inhibiting pesticides/|For more Mechanism of Action (Complete) data for OMETHOATE (6 total), please visit the HSDB record page.

A comatose patient who is diaphoretic, has pinpoint pupils and the odor of an insecticide on clothing or breath, and is noted to have muscle fasciculations represents the classic presentation of organophosphate poisoning. ... Specific steps in management include the following. 1. Decontamination. ... 2 Airway. Establish an airway if necessary. ... 3. Respiratory Status. Respiratory distress, in fact, is commonly found in these patients from multiple causes. ... 4. Cardiac Monitoring. ... 5. Cholinesterase Level. ... 6. Pralidoxime. Pralidoxime is the treatment of choice for organophosphate poisoning and should be used for nearly all patients with clinically significant orgnophosphate poisoning,particularly whose patients with muscular fasciculations and weakness. ... 7. Atropine. Atropine is the physiologic antidote for organophosphate poisoning. A trial dose of atropine should be instituted on clinical ground when one suspects organophosphate intoxication. /Organophosphate poisoning/|Atropine ... may be useful without reaching complete atropinization (dilated pupils, dry or red skin, confusion, tachycardia, fever ileus). ... Pralidoxime is usually unnecessary and may reduce the effectiveness of atropine, although it may reduce fasciculations. Patients may require 6-8 hours of atropine treatment. Significant poisoning may require at least 24 hours of observation after the last atropine dose. /Organophosphate poisoning/|Atropine, possibly in conjunction with ... /pralidoxime/, Toxogonin, or other cholinesterase reactivators.|/SRP:/ Basic treatment: Establish a patent airway (oropharyngeal or nasopharyngeal airway, if needed). Suction if necessary. Aggressive airway control may be needed. Watch for signs of respiratory insufficiency and assist ventilations if necessary. Administer oxygen by nonrebreather mask at 10 to 15 L/min. Monitor for pulmonary edema and treat if necessary ... . Monitor for shock and treat if necessary ... . Anticipate seizures and treat if necessary ... . For eye contamination, flush eyes immediately with water. Irrigate each eye continuously with 0.9% saline (NS) during transport ... . Do not use emetics. For ingestion, rinse mouth and administer 5 ml/kg up to 200 ml of water for dilution if the patient can swallow, has a strong gag reflex, and does not drool. Administer activated charcoal ... . /Organophosphates and related compounds/|/SRP:/ Advanced treatment: Consider orotracheal or nasotracheal intubation for airway control in the patient who is unconscious, has severe pulmonary edema, or is in severe respiratory distress. Positive-pressure ventilation techniques with a bag valve mask device may be beneficial. Monitor cardiac rhythm and treat arrhythmias if necessary ... . Start IV administration of D5W /SRP: "To keep open", minimal flow rate/. Use 0.9% saline (NS) or lactated Ringer's (LR) if signs of hypovolemia are present. For hypotension with signs of hypovolemia, administer fluid cautiously and consider vasopressors if patient is hypotensive with a normal fluid volume. Watch for signs of fluid overload ... . Administer atropine. Correct hypoxia before giving atropine ... . Administer pralidoxime chloride (2 PAM). USE UNDER DIRECT PHYSICIAN ORDERS ONLY ... . Treat seizures with adequate atropinization and correction of hypoxia. In rare cases diazepam or lorazepam may be necessary ... . Watch for signs of fluid overload ... . Use proparacaine hydrochloride to assist eye irrigation ... . /Organophosphates and related compounds/

/SIGNS AND SYMPTOMS/ The symptoms of chronic poisoning due to organophosphorus pesticides include headache, weakness, feeling of heaviness in head, decline of memory, quick onset of fatigue, disturbed sleep, loss of appetite, and loss of orientation. Psychic disorders, nystagmus, trembling of the hands and other nervous system disorders can be observed in certain cases. Sometimes neuritis, paresis and paralysis develop. /Organophosphorus pesticides/|/SIGNS AND SYMPTOMS/ Organophosphorus compounds can produce dermal irritation but most are weak sensitizers. /Organophosphate compounds/|/SIGNS AND SYMPTOMS/ Toxic effects may include anorexia, abdominal cramps, nausea, vomiting, diarrhea, incontinence, eye changes, weakness, dyspnea, bronchospasm, lacrimation, increased salivation and sweating, bradycardia, hypotension or hypertension due to asphyxia, cyanosis, and muscular twitching of the eyelids, tongue, face, and neck, possibly progressing to convulsions. Central nervous system symptoms include restlessness, anxiety, dizziness, drowsiness, tremor, ataxia, depression, confusion, and coma. Death may occur from depression of the respiratory or cardiovascular system. Neuropathy appears to be a rare problem with the organophosphorus insecticides now in use. /Organophosphorus insecticides/|/CASE REPORTS/ A woman at 34 to 35 wk gestation presented in acute respiratory distress with cyanosis and tachypnea and bilateral rhonchi and crepitation. Her heart rate was 78 beats per minute and her blood pressure 120/80 mm Hg, with a fetal heart rate of 140 beats per minute. The mother was salivating markedly and her pupils were reduced to "pinpoint size." An uncorrected metabolic acidosis was diagnosed. Serum and erythrocyte acetylcholinesterase determinations were near zero. Cholinesterase inhibitor poisoning was felt to be the likely cause of disorders. Administration of atropine ...lead to unacceptable fetal tachycardia. The woman had shown increased cooperativeness and secretion control until the atropine had to be stopped. A cesarean section was performed for delivery of a hypotonic infant with a 1 minute Apgar score of 3. The baby was mechanically ventilated for 2 days and required atropine therapy... for 8 days. The mother required 8 days of mechanical ventilation and 11 days of atropine therapy. In this case, the infant appeared relatively less poisoned than the mother by a presumed organophosphate exposure. /Organophosphate poisoning/|For more Human Toxicity Excerpts (Complete) data for OMETHOATE (10 total), please visit the HSDB record page.

dimethoxon

Aerosol dispenser; emulsifiable concentrate; soluble concentrate; ultra-low volume liquid|Mixtures: (omethoate+) tetradifon; dicofol + tetradifon; cyfluthrin|...Technical omethoate has the following composition: Omethoate min 94.5%, O-desmethyl-omethoate max 2.0%, Dimethyl phosphite max 2.0%, Solvents max 2.0%.

The WHO Recommended Classification of Pesticides by Hazard identifies Omethoate (technical grade) as Class IB: highly hazardous; Main Use: insecticide.|Not registered for use in U.S.|P-O analogue of dimethoate

Residues determined by reverse phase high performance liquid chromatography|FDA; Pesticide Analytical Manual Vol 1, Sec 232.41 (1989) Determination of omethoate by gas liquid chromatography method with electron conductivity detector. Method is applicable to nonfatty foods. Recovery is not recovered.|A TLC method is reported for the sepn of dimethoate, dimethoate (oxygen analog), dioxathion, disulfoton, fonofos, fonofos (oxygen analog), and oxydemetonmethyl. The method involves the concurrent use of 2 Eastman silica gel plates with fluorescent indicator and 2 solvent systems. One plate is developed in solvent system containing 2,2,4-trimethylpentane: methylcyclohexane: isoamyl alcohol: paraffin oil: acetone (4:2:2:3:1) and the other in solvent system contg n-heptane: xylene: benzene: toluene: cyclohexane: methylcyclohexane (1:1:1:1:1:1). The pesticides are located by spraying with ammoniacal silver nitrate in acetone followed by exposure to long-wave UV light after drying at 100 °C for 2-3 min. A method is also reported for the TLC sepn of diazinon, dimethoate, dimethoate (oxygen analog), dioxathion, fonofos (oxygen analog), and oxydemetonmethyl from each other on fluorescent silica gel plates using solvent system containing 2,2,4-trimethylpentane: methylcyclohexane: isoamyl alcohol: paraffin oil: acetone (4:2:2:3:1).|Method: AOAC 985.22; Procedure: gas chromatography; Analyte: omethoate; Matrix: lettuce, strawberries, and tomatoes; Detection Limit: not provided.

Agrochemicals -> Acaricides, Insecticides|Transformation products, Acaricides, Insecticides|Environmental transformation -> Pesticide transformation products (metabolite, successor)

Omethoate is a known environmental transformation product of dimethoate.|Omethoate is a known environmental transformation product of Dimethoate.