Methomyl

162.21000

162.21

240-815-0

0177

2811|2757

DTXSID1022267

White crystalline solid

2930909052

75.99000

1.42970

1.3 g/cm³

78-79 °C

144ºC

1.508

H2O: soluble . 5.8 g/100 mL

0-6ºC

5e-05 mm Hg at 77 °F (EPA, 1998)|5.4X10-6 mm Hg @ 25 °C|Vapor pressure at 25 °C: negligible|0.00005 mmHg at 77°F|(77°F): 0.00005 mmHg

Slightly sulfurous

141.89 Ų [M+Na]+

Water soluble.

Carbamates

METHOMYL is a carbamate ester. Carbamates are chemically similar to, but more reactive than amides. Like amides they form polymers such as polyurethane resins. Carbamates are incompatible with strong acids and bases, and especially incompatible with strong reducing agents such as hydrides. Flammable gaseous hydrogen is produced by the combination of active metals or nitrides with carbamates. Strongly oxidizing acids, peroxides, and hydroperoxides are incompatible with carbamates.

Noncombustible Solid, but may be dissolved in flammable liquids.

AQ SOLN NONCORROSIVE

II

6.1(a)

UN 2757

R28; R50/53

S1/2-S22-S36/37-S60-S61

AK2975000

T+; N

Stable. Incompatible with strong bases, strong oxidizing agents.

P273-P301 + P310 + P330-P391-P501

H300-H410

Generators of waste (equal to or greater than 100 kg/mo) containing this contaminant, EPA hazardous waste number P066, must conform with USEPA regulations in storage, transportation, treatment and disposal of waste.|Landfill: The aqueous soln is noncorrosive. It is stable as a solid, in aqueous soln under normal conditions but is subject to decomposition in moist soil.|Hydrolysis: Alkaline hydrolysis leads to complete degradation. Carbonate, methylamine, and 5-methyl-n-hydroxylthioacetamidate are nontoxic. Recommendable methods: Incineration, landfill. Peer-review: Dissolve methomyl in water and spray into a furnace with effluent gas scrubbing. (Peer-review conclusions of an IRPTC expert consultation (May 1985))|Potential candidate for disposal by rotary kiln incineration with a temperature range of 820-1600 °C and a residence time of seconds for liquids and gases, and hours for solids. Also a potential candidate for fluidized bed incineration with a temperature range of 450-980 °C, with a residence time of seconds for liquids and gases, and longer for solids.

Strong bases.

USEPA/Office of Pesticide Programs; Reregistration Eligibility Decision Document - Methomyl EPA 738-R-98-021. The RED summarizes the risk assessment conclusions and outlines any risk reduction measures necessary for the pesticide to continue to be registered in the U.S.[Available from, as of April 30, 2003: http://www.epa.gov/pesticides/reregistration/status.htm]|WHO; Environ Health Criteria 178: Methomyl (1996). The criteria monographs are intended to provide critical reviews on the effect on human health and the environment of chemicals and of combinations of chemicals and physical and biological agents.

When heated to decomposition, it emits very toxic fumes of nitrogen oxides and sulfur oxides. Do not subject liquid formulations to temperatures below 32F. (EPA, 1998)|Combustible under specific conditions. Liquid formulations containing organic solvents may be flammable. Gives off irritating or toxic fumes (or gases) in a fire.

|Danger|H300: Fatal if swallowed [Danger Acute toxicity, oral]|P264, P270, P273, P301+P310, P321, P330, P391, P405, and P501|H300 (100%): Fatal if swallowed [Danger Acute toxicity, oral]|Aggregated GHS information provided by 290 companies from 8 notifications to the ECHA C&L Inventory. Each notification may be associated with multiple companies.|H301: Toxic if swallowed [Danger Acute toxicity, oral]|P260, P264, P270, P271, P280, P284, P301+P310, P302+P352, P304+P340, P307+P311, P310, P312, P314, P320, P321, P322, P330, P363, P403+P233, P405, and P501

(Non-Specific -- Carbamate Pesticide, Solid) Wear self-contained breathing apparatus. (Non-Specific -- Carbamate Pesticide, Solid) Use agent suitable for type of surrounding fire. Use water in flooding quantities as a fog. Use alcohol foam, carbon dioxide, or dry chemical. (EPA, 1998)|Use water spray, foam, powder, carbon dioxide.

Excerpt from ERG Guide 154 [Substances - Toxic and/or Corrosive (Non-Combustible)]: As an immediate precautionary measure, isolate spill or leak area in all directions for at least 50 meters (150 feet) for liquids and at least 25 meters (75 feet) for solids. SPILL: Increase, in the downwind direction, as necessary, the isolation distance shown above. FIRE: If tank, rail car or tank truck is involved in a fire, ISOLATE for 800 meters (1/2 mile) in all directions; also, consider initial evacuation for 800 meters (1/2 mile) in all directions. (ERG, 2016)

Caution : Flammable. Avoid sources of extreme heat or ignition including sparks or fire. Methomyl will liberate toxic nitrogen and sulfur oxide fumes when heated to decomposition. (Non-Specific -- Carbamate Pesticide, Solid) Keep unnecessary people away; isolate hazard areas and deny entry. Stay upwind and keep out of low areas. Do not touch spilled material, or handle broken packages without protective equipment. Do not breathe dust, vapors, or the fumes from burning material. (EPA, 1998)

Skin: Wear appropriate personal protective clothing to prevent skin contact. Eyes: Wear appropriate eye protection to prevent eye contact. Wash skin: The worker should immediately wash the skin when it becomes contaminated. Remove: Work clothing that becomes wet or significantly contaminated should be removed and replaced. Change: Workers whose clothing may have become contaminated should change into uncontaminated clothing before leaving the work premise. Provide: Facilities for quickly drenching the body should be provided within the immediate work area for emergency use where there is a possibility of exposure. [Note: It is intended that these facilities provide a sufficient quantity or flow of water to quickly remove the substance from any body areas likely to be exposed. The actual determination of what constitutes an adequate quick drench facility depends on the specific circumstances. In certain instances, a deluge shower should be readily available, whereas in others, the availability of water from a sink or hose could be considered adequate.] (NIOSH, 2016)|Wear protective clothing, goggles, and a mask or respirator suitable for protection against methomyl vapors or dusts.|Wear appropriate personal protective clothing to prevent skin contact.|Wear appropriate eye protection to prevent eye contact.|Facilities for quickly drenching the body should be provided within the immediate work area for emergency use where there is a possibility of exposure. [Note: It is intended that these facilities provide a sufficient quantity or flow of water to quickly remove the substance from any body areas likely to be exposed. The actual determination of what constitutes an adequate quick drench facility depends on the specific circumstances. In certain instances, a deluge shower should be readily available, whereas in others, the availability of water from a sink or hose could be considered adequate.]|(See protection codes)

Liquid formulations flammable.

A system for removing pesticides from the wash water produced by pesticide applicators as they clean their equipment has been developed. The first step is the flocculation/coagulation and sedimentation of the pesticide-contaminated wash water. The supernatant from the first step is then passed through activated carbon columns. /Pesticides/

Smoking, eating and drinking before washing should be absolutely prohibited when any pesticide of moderate or higher toxicity is being handled or used. /Pesticides/|The worker should immediately wash the skin when it becomes contaminated.|Work clothing that becomes wet or significantly contaminated should be removed and replaced.|Workers whose clothing may have become contaminated should change into uncontaminated clothing before leaving the work premises.|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.

/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. /Carbamate pesticide, liquid, flammable, poisonous; Carbamate pesticide, liquid, flammable, toxic; Carbamate pesticide, liquid, poisonous, flammable; Carbamate 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. /Carbamate pesticide, liquid, flammable, poisonous; Carbamate pesticide, liquid, flammable, toxic; Carbamate pesticide, liquid, poisonous, flammable; Carbamate 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. /Carbamate pesticide, liquid, flammable, poisonous; Carbamate pesticide, liquid, flammable, toxic; Carbamate pesticide, liquid, poisonous, flammable; Carbamate 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. /Carbamate pesticide, liquid, flammable, poisonous; Carbamate pesticide, liquid, flammable, toxic; Carbamate pesticide, liquid, poisonous, flammable; Carbamate pesticide, liquid, toxic, flammable/|For more DOT Emergency Guidelines (Complete) data for METHOMYL (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.

/Methomyl/ is a pulmonary irritant ... .

Vacated 1989 OSHA PEL TWA 2.5 mg/cu m is still enforced in some states.

Recommended Exposure Limit: 10 Hr Time-Weighted Avg: 2.5 mg/cu m.

Personal protection: particulate filter respirator adapted to the airborne concentration of the substance. Do NOT let this chemical enter the environment. Sweep spilled substance into covered sealable containers. If appropriate, moisten first to prevent dusting. Carefully collect remainder. Then store and dispose of according to local regulations.

Store in an area without drain or sewer access. Dry. Keep in a well-ventilated room. Separated from strong bases and food and feedstuffs.

A harmful contamination of the air will not or will only very slowly be reached on evaporation of this substance at 20 °C; on spraying or dispersing, however, much faster.

The substance is irritating to the eyes. The substance may cause effects on the nervous system. This may result in convulsions and respiratory depression. Cholinesterase inhibition. Exposure far above the OEL could cause death.

The substance may have effects on the blood. This may result in anaemia.

NO open flames.

PREVENT DISPERSION OF DUST! STRICT HYGIENE! AVOID EXPOSURE OF ADOLESCENTS AND CHILDREN!

Use local exhaust or breathing protection.

Protective gloves.

Wear safety goggles or eye protection in combination with breathing protection.

P066; An acute hazardous waste when a discarded commercial chemical product or manufacturing chemical intermediate or an off-specification commercial chemical product or a manufacturing chemical intermediate.

Persons in charge of vessels or facilities are required to notify the National Response Center (NRC) immediately, when there is a release of this designated hazardous substance, in an amount equal to or greater than its reportable quantity of 100 lb or 45.4 kg. The toll free number of the NRC is (800) 424-8802; In the Washington D.C. metropolitan area (202) 426-2675. The rule for determining when notification is required is stated in 40 CFR 302.4 (section IV. D.3.b).|Releases of CERCLA hazardous substances are subject to the release reporting requirement of CERCLA section 103, codified at 40 CFR part 302, in addition to the requirements of 40 CFR part 355. Methomyl is an extremely hazardous substance (EHS) subject to reporting requirements when stored in amounts in excess of its threshold planning quantity (TPQ) of 500 or 10,000 lbs. Extremely hazardous substances that are solids are subject to either of two threshold planning quantities ... The lower quantity applies only if the solid exists in powdered form and has a particle size less than 100 microns; or is handled in solution or in molten form; or meets the criteria for a National Fire Protection Association (NFPA) rating of 2, 3 or 4 for reactivity. If the solid does not meet any of these criteria, it is subject to the upper ... threshold planning quantity ... .

P066; As stipulated in 40 CFR 261.33, when methomyl, as a commercial chemical product or manufacturing chemical intermediate or an off-specification commercial chemical product or a manufacturing chemical intermediate, becomes a waste, it must be managed according to federal and/or state hazardous waste regulations. Also defined as a hazardous waste is any container or inner liner used to hold this waste or any residue, contaminated soil, water, or other debris resulting from the cleanup of a spill, into water or on dry land, of this waste. Generators of small quantities of this waste may qualify for partial exclusion from hazardous waste regulations (40 CFR 261.5(e)).

SOURCE DOMINATED: Methomyl was detected in the aerosol phase in a greenhouse 24 hours after spraying at concns of 1-7 ppb(1).

... The effects of common agricultural carbamate insecticides, aldicarb and methomyl, and a triazine herbicide, metribuzin, on hormone levels in Sprague-Dawley rats /were examined/. Fifty-four female rats were sampled at 2 and 6 wk during a 6-wk exposure to individual chemicals or to combinations of them. ... Rats treated with the herbicide (metribuzin) were hyperthyroid. The interactions of all three chemicals also significantly increased thyroxine levels. ... These experiments /were reported/ for 16 wk using 54 male rats; the results were very similar. Metribuzin alone significantly increased thyroxine throughout the second study (at 7, 13, and 16 wk). Somatotropin levels were significantly altered after 13 wk of exposure. The same concentrations and mixtures of these three pesticides have now been shown to be implicated in learning impairment and other neurological functions, immune parameter changes, and endocrine changes. These findings support the concept of the interconnectedness of the nervous, endocrine, and immune systems and raise the likelihood of impacts on all three systems if one is shown to be affected. ...|Combined effects of pesticides & ozone pollutants on pinto bean seedlings were examined. The insecticides diazinon & methomyl were applied to pinto bean seedlings at the recommended concns of 1 oz/3 gal water & 0.5 lb/100 gal water respectively. Both insecticides interacted with ozone applied at rates of 30 /part per hundred/ to produce /noteworthy/ alterations in foliar injury for the bean seedlings.|Compounds with synergistic effects (assessed as either excess mortality or greater inhibition of blood cholinesterase activity) included carbaryl, ronnel, methyl parathion, & mevinphos. Dimethoate was antagonistic; a mixture with methomyl inhibited cholinesterase 53% less than predicted. Compounds producing only additive effects included endosulfan & diflubenzuron. In mice, pretreatment with butylated hydroxyanisole (BHA) for 4 days reduced the LD50 of methomyl by a factor of 2.2-3.2.|Oximes may form a toxic complex with the carbamate & may diminish atropine effectiveness, & in many cases, are not necessary to revert the intoxication.

LD50 Rat (male) oral 17 mg active ingredient/kg|LD50 Rat (female) oral 24 mg active ingredient/kg|LD50 Rabbit (male) percutaneous >5000 mg ai/kg|LD50 Rat sc 9 mg/kg|For more Non-Human Toxicity Values (Complete) data for METHOMYL (11 total), please visit the HSDB record page.

/BIRDS and MAMMALS/ Methomyl (S-methyl-N-((methylcarbamoyl)oxy) thioacetimidate) toxicity was studied in horses using iv dosages from 0.01 to 3.0 mg/kg. Doses of 1-3 mg methomyl/kg produced increased GI motility and respirations, facial fasiculations, salivation, lacrimation and convulsions. The only effect at 0.5 mg/kg was increased GI sounds in 1/4 horses. This extensively used crop insecticide had been associated with episodes of morbidity and mortality and led to speculation that it was extremely potent to the horse. This was not supported by these clinical studies.|/BIRDS and MAMMALS/ SIGNS OF INTOXICATION /IN MALLARDS FROM ACUTE ORAL EXPOSURE/: HIGH CARRIAGE, ATAXIA, DROWSINESS, TACHYPNEA, DYSPNEA, SALIVATION, TENESMUS, DIARRHEA, TREMORS, TETANY, OR WING-BEAT CONVULSIONS.|/BIRDS and MAMMALS/ 30-DAY EMLD /EMPIRICAL MINIMUM LETHAL DOSAGE/ FOR 17- TO 22-WK-OLD MALLARDS... IS 7.5 MG/KG/DAY FOR BOTH SEXES. THE RESULTING CUMULATIVE TOXICITY INDEX IS 15.9/7.5 = 2.1, INDICATING LITTLE OR NO CUMULATIVE TOXIC ACTION. /SAMPLE PURITY 90%/|/AQUATIC SPECIES/ /Data from acute toxicity studies on fathead minnows exposed to LC50 concn of 99% pure methomyl for 96 hr showed that/ affected fish lost schooling behavior, were hyperactive & swam near the tank surface. They were also overreactive to external stimuli, had incr resp, were darkly colored & lost equilibrium prior to death.|For more Ecotoxicity Excerpts (Complete) data for METHOMYL (8 total), please visit the HSDB record page.

Methomyl's production may result in its release to the environment through various waste streams; it's use as an insecticide(1) will result in its direct release to the environment(SRC).

ONE DOES NOT EXPECT TO FIND RESIDUES OF ... METHOMYL IN SOIL BEYOND GROWING SEASON DURING WHICH IT WAS APPLIED. VERY LITTLE DATA ON BEHAVIOR OF ALDICARB & METHOMYL IN WATER ARE AVAILABLE. IN STUDY OF POND & LAKE WATER, HALF-LIFE OF 5 DAYS & 6 DAYS WERE DETERMINED FOR ALDICARB & METHOMYL, RESPECTIVELY.|IN SOIL, LABELED METHOMYL WAS DEGRADED TO (14)CO2 & OTHER MATERIALS, SOME OF WHICH WERE REINCORPORATED INTO NORMAL COMPONENTS OF SOIL ORG MATTER.|TERRESTRIAL FATE: Methomyl effectively controlled fall armyworm larvae in stands of Coastal Bermuda grass. Residues of methomyl declined rapidly with time after application, and by 7 days about 7% of the initial deposit remained regardless of the rate of application. Methomyl loss during dehydration in a natural gas dryer was approx 54%. The pelletizing process caused an additional loss of approx 14%. Thus, the total loss of methomyl during processing of green hay to pellets amounted to approx 68%. Losses of residues during air curing of hay in the field amounted to approx 37%.|TERRESTRIAL FATE: Based on a classification scheme(1), a Koc value of 160(2), indicates that methomyl is expected to have moderate mobility in soil(SRC). Volatilization of methomyl from moist soil surfaces is not expected to be an important fate process(SRC) given an estimated Henry's Law constant of 1.9X10-11 atm-cu m/mole(SRC), derived from its vapor pressure, 5.4X10-6 mm Hg(3), and water solubility, 58,000 mg/l(4). Methomyl is not expected to volatilize from dry soil surfaces(SRC) based upon its vapor pressure(3). Methomyl degrades readily in soils, with half-lives of 3-14 days reported in 3 different greenhouse soils(5) and 5-6 weeks in tobacco growing soils(6).|For more Environmental Fate (Complete) data for METHOMYL (6 total), please visit the HSDB record page.

The rate constant for the vapor-phase reaction of methomyl with photochemically-produced hydroxyl radicals has been estimated as 6.6X10-12 cu cm/molecule-sec at 25 °C(SRC) using a structure estimation method(1). This corresponds to an atmospheric half-life of about 58 hours at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm(1). Methomyl exhibited hydrolysis half-lives of 56, 54, 38, and 20 weeks at pH's of 4.5, 6.0, 7.0, and 8.0, respectively, in sterile water-ethanol (99:1) at 25 °C(2). A rate constant of 8.9X10-5 1/hr has been determined for the hydrolysis of methomyl in pure water at 25 °C (pH=7), which translates to a half-life of 262 days(3). The photodegradative half-life for a thin film of methomyl exposed to laboratory lamps of environmentally important wavelengths was 48.41 hours(4). In acetonitrile solution, methomyl strongly absorbs UV light between 295 and 305 nm indicating a potential for direct photolysis in vapor and aqueous phase(4).

An estimated BCF of 3 was calculated for methomyl(SRC), using a log Kow of 0.6(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 measured Koc of methomyl was reported as 160(1). According to a classification scheme(2), this Koc value suggests that methomyl is expected to have moderate mobility in soil. Under field conditions and using laboratory studies, only slight movement of methomyl has been observed in soil(3,4).

The Henry's Law constant for methomyl is estimated as 1.9X10-11 atm-cu m/mole(SRC) derived from its vapor pressure, 5.4X10-6 mm Hg(1), and water solubility, 58,000 mg/l(2). This Henry's Law constant indicates that methomyl is expected to be essentially nonvolatile from water surfaces(3). Methomyl's estimated Henry's Law constant indicates that volatilization from moist soil surfaces is not expected to be an important environmental fate process(SRC). Methomyl is not expected to volatilize from dry soil surfaces(SRC) based upon its vapor pressure(1).

Methomyl was detected in 4 groundwater wells in Spain at concns of not detected to 300 ng/l(1). Methomyl was identified, not quantified, in groundwater near golf courses(2). Methomyl was detected at a max concn of 0.14 ug/l in an urban stream in Las Vegas, NV(3). Methomyl was detected in 2 of 446 surface water samples, and 25 of 1,023 groundwater samples in the US, at max concns of 2 and 10 ug/l, respectively(4).

Methomyl was detected in 15 of 319 food samples analyzed between 1980 and 1983 at the following concn: cabbage, 0.02-0.41 ppm; cantaloupe, 0.02 ppm; cucumbers, 0.04 ppm; grapes, 0.01-0.04 ppm; lettuce, 0.12 ppm; romaine, 0.02 ppm; squash, 0.06 ppm; potatoes, below 0.01 ppm(1). One market basket from USA FDA's Total Diet Program for 1983 contained 0.07 ppm methomyl in boiled collards and 0.067 ppm methomyl in raw strawberries(1). Methomyl was found in 126 of 19,851 domestic and imported food and feed commodities obtained in Los Angeles, CA, 1982-86, at a concn of 0.05-2.0 ppm (4 samples at a concn >2 ppm)(2). Methomyl was identified, not quantified, in 121 of 6,391 domestic commodities and 5 of 12,044 imported commodities(3).

THERE HAVE BEEN REPORTS OF OCCUPATIONAL EXPOSURE POISONINGS ... FROM METHOMYL WHEN ... INHALED BY WORKERS IN FORMULATING PLANTS. IT IS DIFFICULT ... TO EVALUATE SUCH POISONINGS, SINCE WORKERS ... ARE OCCUPATIONALLY EXPOSED ... TO ... ORGANOPHOSPHORUS INSECTICIDES AS WELL. ... NO CONTROLLED STUDIES.|Occupational exposure to methomyl may occur through inhalation of dust and dermal contact with this compound at workplaces where methomyl is produced or used. Monitoring data indicate that the general population may be exposed to methomyl via ingestion of food products containing methomyl. (SRC)|The concn of methomyl detected in the ambient air of a storage room of a commercial pest control building was 13.7 ng/cu m over a 3 hr monitoring period(1); conversion of this concn to a 40-hr work week is 0.180 ug/cu m which is far below the TLV-TWA value of 2500 ug/cu m(1).|Concn detected in the gas phase were in the range of less than 1-7 ppb. Methomyl was present in the aerosol phase in the greenhouse air for 24 hr after spraying.

A lethal dose is approx 12-15 mg/kg.

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. (See all compounds classified as Cholinesterase Inhibitors.)|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. (See all compounds classified as Insecticides.)

EXPIRED AIR COLLECTED FOLLOWING ADMIN OF /LABELLED/ METHOMYL TO RATS CONTAINED LABELED CO2 & ACETONITRILE.|... The course of therapy & symptoms for a patient who had attempted suicide by ingesting about 2.25 g of methomyl /was reported/. At 6 hr postingestion, methomyl was present in the blood at 1.61 ppm & in the urine at 10.91 ppm; at 15 hr, levels were 0.04 ppm in the blood & 0.25 ppm in the urine; & at 22 hr, methomyl was not detectable in the samples.|Near complete (95-98%) absorption of a single 5 mg/kg oral dose of 14 carbon-labeled methomyl occurred in female CD or male rats. Male rats fed 14 carbon-labeled methomyl eliminated almost all of the labeled material in 24 hr. 10% or less of the original radiolabel was found in the whole body & organs one day after treatment. Urine (25%), respiratory carbon dioxide (25%), & acetonitrile (50%) accounted for most of the recovered radioactivity. No parent methomyl appeared in the urine.|One hour after the dermal applications of (14)C-methomyl to mice ..., 2.9% of the dose was present in blood, 5% in liver and 56% in the remaining carcass. After 8 h the distribution was 6.1% in blood, 3.3% in liver, 3.8% in the gastrointestinal tract and smaller amounts (< 1%) in other individual tissues. The remaining carcass contained 15% of the original dose ... .|For more Absorption, Distribution and Excretion (Complete) data for METHOMYL (8 total), please visit the HSDB record page.

(14)C-METHOMYL ... WAS BIOTRANSFORMED IN RATS INTO (14)CO2 (ABOUT 25%), ACETONITRILE (ABOUT 50%), & UNIDENTIFIED URINARY METABOLITES (ABOUT 25%). ABSENCE IN URINE OF PARENT OXIME & ... SULFOXIDE & SULFONE OF PARENT CMPD WAS CONFIRMED BY COMPARISON STUDIES WITH AUTHENTIC MATERIAL.|... METABOLISM OF METHOMYL IS PRIMARILY BY HYDROLYTIC ROUTE. PRINCIPAL METABOLITES FOUND IN URINE FOLLOWING TREATMENT OF RATS WITH (14)C-LABELED METHOMYL WERE OXIME-O-SULFATE, FREE OXIME, OXIME GLUCURONIDE ... .|Methomyl can exist in 2 geometric configurations. ... In rats, carbonyl- or oximino-labeled syn-methomyl was metabolized to carbon dioxide & acetonitrile at a 2:1 ratio. In contrast, the anti isomer was metabolized predominately to acetonitrile. It was concluded on the basis of this & other evidence that a Beckman rearrangement of the syn & anti oximes occurs prior to formation of carbon dioxide & acetonitrile.|In rats, methomyl was rapidly converted to methomyl methylol, oxime, sulfoxide, & sulfoxide oxime; these unstable intermediates were converted to acetonitrile & carbon dioxide, which were eliminated primarily via respiration & in the urine.|For more Metabolism/Metabolites (Complete) data for METHOMYL (7 total), please visit the HSDB record page.

INHIBITION OF ACETYLCHOLINESTERASE.|Methomyl was among 24 pesticides tested for interactions with the estrogen receptor (ER) and the androgen receptor (AR) in transactivation assays. Estrogen-like effects on MCF-7 cell proliferation and effects on CYP19 aromatase activity in human placental microsomes were also investigated. Methomyl weakly stimulated aromatase activity.|Lannate 1 -(methomyl) was incubated with erythrocytes of rats at different concentrations. ... There was a decrease in the activities of superoxide dismutase and glutathione reductase after 1/2 and 16 hour of Lannate addition. There was also a decrease in the amount of glutathione. The inhibition of enzyme activities and the decrease in glutathione concentration were dose independent. The results suggest that Lannate toxicity might lead to hemolysis, oxidation of hemoglobin and finally induced erythropenia. /Lannate/

Methomyl has high oral toxicity, moderate inhalation toxicity and low skin toxicity. The probable oral lethal dose for humans is between 7 drops and 1 teaspoon for a 150 pound adult. Death is due to respiratory arrest. (EPA, 1998)

Signs and Symptoms of Acute Methomyl Exposure: Acute exposure to methomyl usually leads to a cholinergic crisis. Signs and symptoms may include increased salivation, lacrimation (tearing), spontaneous defecation, and spontaneous urination. Pinpoint pupils, blurred vision, tremor, muscle twitching, and loss of muscle coordination may occur. Mental confusion, convulsions, and coma may also be noted. Gastrointestinal effects include nausea, vomiting, diarrhea, and abdominal pain. Bradycardia (slow heart rate) occurs frequently. Dyspnea (shortness of breath), pulmonary edema, and respiratory arrest may also occur. Emergency Life-Support Procedures: Acute exposure to methomyl may require decontamination and life support for the victims. Emergency personnel should wear protective clothing appropriate to the type and degree of contamination. Air-purifying or supplied-air respiratory equipment should also be worn, as necessary. Rescue vehicles should carry supplies such as plastic sheeting and disposable plastic bags to assist in preventing spread of contamination. Inhalation Exposure: 1. Move victims to fresh air. Emergency personnel should avoid self-exposure to methomyl. 2. Evaluate vital signs including pulse and respiratory rate, and note any trauma. If no pulse is detected, provide CPR. If not breathing, provide artificial respiration. If breathing is labored, administer oxygen or other respiratory support. 3. Obtain authorization and/or further instructions from the local hospital for administration of an antidote or performance of other invasive procedures. 4. Transport to a health care facility. Dermal/Eye Exposure: 1. Remove victims from exposure. Emergency personnel should avoid self- exposure to methomyl. 2. Evaluate vital signs including pulse and respiratory rate, and note any trauma. If no pulse is detected, provide CPR. If not breathing, provide artificial respiration. If breathing is labored, administer oxygen or other respiratory support. 3. Remove contaminated clothing as soon as possible. 4. If eye exposure has occurred, eyes must be flushed with lukewarm water for at least 15 minutes. 5. Wash exposed skin areas three times with soap and water. 6. Obtain authorization and/or further instructions from the local hospital for administration of an antidote or performance of other invasive procedures. 7. Transport to a health care facility. Ingestion Exposure: 1. Evaluate vital signs including pulse and respiratory rate, and note any trauma. If no pulse is detected, provide CPR. If not breathing, provide artificial respiration. If breathing is labored, administer oxygen or other respiratory support. 2. Obtain authorization and/or further instructions from the local hospital for administration of an antidote or performance of other invasive procedures. 3. Vomiting may be induced with syrup of Ipecac. If elapsed time since ingestion of methomyl is unknown or suspected to be greater than 30 minutes, do not induce vomiting and proceed to Step 4.Ipecac should not be administered to children under 6 months of age.Warning: Ingestion of methomyl may result in sudden onset of seizures or loss of consciousness. Syrup of Ipecac should be administered only if victims are alert, have an active gag-reflex, and show no signs of impending seizure or coma. If ANY uncertainty exists, proceed to Step 4.The following dosages of Ipecac are recommended: children up to 1 year old, 10 mL (1/3 oz); children 1 to 12 years old, 15 mL (1/2 oz); adults, 30 mL (1 oz). Ambulate (walk) the victims and give large quantities of water. If vomiting has not occurred after 15 minutes, Ipecac may be readministered. Continue to ambulate and give water to the victims. If vomiting has not occurred within 15 minutes after second administration of Ipecac, administer activated charcoal. 4. Activated charcoal may be administered if victims are conscious and alert. Use 15 to 30 g (1/2 to 1 oz) for children, 50 to 100 g (1-3/4 to 3-1/2 oz) for adults, with 125 to 250 mL (1/2 to 1 cup) of water. 5. Promote excretion by administering a saline cathartic or sorbitol to conscious and alert victims. Children require 15 to 30 g (1/2 to 1 oz) of cathartic; 50 to 100 g (1-3/4 to 3-1/2 oz) is recommended for adults. 6. Transport to a health care facility. (EPA, 1998)|(See procedures)

Fresh air, rest. Half-upright position. Refer for medical attention.

Remove contaminated clothes. Rinse skin with plenty of water or shower.

First rinse with plenty of water for several minutes (remove contact lenses if easily possible), then refer for medical attention.

Basic treatment: Establish a patent airway. 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 normal saline 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 ... . /Carbamates and related compounds/|Advanced treatment: Consider orotracheal or nasotracheal intubation for airway control in the patient who is unconscious. Positive pressure ventilation techniques with a bag valve mask device may be beneficial. Monitor cardiac rhythm and treat arrhythmias if necessary ... . Start an IV with D5W /SRP: "To keep open", minimal flow rate/. Use lactated Ringer's if signs of hypovolemia are present. For hypotension if signs of hypovolemia are present, administer fluid cautiously. Watch for signs of pulmonary edema ... . Administer atropine. Correct hypoxia before administration ... . In severely poisoned patients, administer pralidoxime chloride (2 PAM). DIRECT PHYSICIAN ORDERS ONLY ... . Treat seizures with adequate atropinization and correction of hypoxia. Rarely is diazepam necessary ... . Use proparacaine hydrochloride to assist eye irrigation ... . /Carbamates and related compounds/|Symptomatic treatment of the carbamate insecticide-poisoned patient, including aggressive respiratory support & the use of atropine to reverse severe muscarinic manifestations, is the same as with organophosphate insecticide poisoning. Because of the shorter duration of effect, atropine therapy is usually required for <24 hr. The principal difference in therapy for carbamate & organophosphate insecticide exposure involves pralidoxime. 2-PAM is relatively contraindicated in carbamate insecticide poisoning, because it may enhance acetylcholinesterase inactivation. After mixed or combined exposures involving both organophosphate & carbamate insecticides or in severe poisonings with an unidentified anticholinesterase agent, it is reasonable cautiously to administer 2-PAM. /Carbamate insecticides/|Patients should be admitted to an intensive care facility where access to a central line, oxygen, & cardiac monitoring will be available. Exposure after spraying will require careful washing of the entire (nails, intertriginous areas) body with tincture of green soap (contains alcohol, useful to remove fat-soluble compounds). Remove all contaminated clothing. Immediate life-threatening symptoms usually result from weakness of the respiratory muscles, central respiratory depression, bronchospasm, bronchial secretions, & pulmonary edema, all of which may result in hypoxemia. Frequent suctioning, endotracheal intubation, & ventilatory assistance may be required. Monitor the /phosphorous dioxide/ with repeat arterial blood gases. Excessive secretions & bronchospasm should respond to adequate doses of atropine. Gastric lavage & activated charcoal should be used if the patient presents within 4 hr after exposure. Health personnel should use rubber gloves & avoid direct contact with contaminated material. ... Follow the patient for any signs of respiratory failure for at least 24 hr after the last atropine dose. Administer fluids to replace losses. Avoid CNS depressants (e.g., opiates); they may incr the possibility of respiratory arrest.|For more Antidote and Emergency Treatment (Complete) data for METHOMYL (18 total), please visit the HSDB record page.

/HUMAN EXPOSURE STUDIES/ Three out of five victims of accidental poisoning from a contaminated meat died within 3 hr of the ingestion. It was estimated that the victims had consumed about 12-15 mg methomyl/kg bw. A 31-yr-old woman and her 6-yr old son, both of whom died as a result of deliberate poisoning, showed concentrations of methomyl in the liver of 15.4 and 56.5 mg/kg, respectively. The estimated doses were 55 mg/kg body weight for the mother and 13 mg/kg bw for the son. Six hours after ingesting approximately 2.25 g methomyl, a woman's blood contained 1.6 mg methomyl/kg. Methomyl could not be detected 22 hr after ingestion... .|/HUMAN EXPOSURE STUDIES/ A 79 yr old man and his 73 yr old wife attempted suicide by ingesting methomyl powder. The woman died within 19 hr but the husband survived after treatment by gastrolavage, followed by admin of atropine sulfate. The serum methomyl concn in the woman was 44 mg/kg I hr after ingestion and 0.2 mg/kg in the blood at autopsy. The methomyl blood concn of the man was 0.01-0.1 mg/kg 28 hr after ingestion ... .|/HUMAN EXPOSURE STUDIES/ Among Japanese tea-growers reporting acute symptoms (fatigue, headache, & profuse perspiration) following pesticide use, 42% named methomyl as one of the chemicals used.|/HUMAN EXPOSURE STUDIES/ Three men died after ingesting approx 12-15 mg/kg bw of methomyl accidentally baked in bread. A fourth who, like the others, displayed twitching, spasms, fasciculations, & difficulty in respiratory embarrassment, responded ... to ... treatment.|For more Human Toxicity Excerpts (Complete) data for METHOMYL (14 total), please visit the HSDB record page.

Lannate

The substance can be absorbed into the body by inhalation of its aerosol and by ingestion.|inhalation, ingestion, skin and/or eye contact

irritation eyes; blurred vision, miosis; salivation; abdominal cramps, nausea, vomiting; dyspnea (breathing difficulty); lassitude (weakness, exhaustion), muscle twitching; liver, kidney damage

Pupillary constriction, muscle cramp, excessive salivation. Muscle twitching. Dizziness. Headache. Sweating. Laboured breathing. Unconsciousness.

Redness. Blurred vision.

Eyes, respiratory system, central nervous system, cardiovascular system, liver, kidneys, blood cholinesterase

ABOUT 50% AS AN INSECTICIDE ON VEGETABLES; ABOUT 50% AS AN INSECTICIDE ON ALFALFA, CORN, COTTON, SOYBEANS, & TOBACCO (1974)|Alfalfa, 17.8%; Grapes, 9.8%; Lettuce, 26%; Sugarbeets, 6.1%; Tomatoes, 8.6%; Citrus, 3.9%; Other vegetables account for most of remainder, 18.1% (1984) /California use, calculated from table/|4.39X10+8 g /Used in California/

USEPA/OPP Pesticide Code 090301; Trade Names: Lannate, Nudrin, Dupont 1179, IN 1179, Insecticide 1179, Mesomile, SD 14999, WL 18236, Lanox 90, Lanox 216, Nu-Bait II, Lurectoron flybait (090301+103201).|Lannate, SP (900 g ai/kg); Lannate L, SL (220 g/l). Mixtures include: Flytek (Zoecon), RB (10 g methomyl + 0.25 g (Z)-tricos-9-ene); methomyl + fenson.|Liquid (1.8 lb ai/gal), low volatility liquid formulation (2.4 lb ai/gal), Lannate LV), 90% water-soluble powder.|"Lannate" LV Insecticide (29% methomyl contains methanol).|Methomyl is a mixture of (Z)- and (E)- isomers (the former predominating)

The WHO Recommended Classification of Pesticides by Hazard identifies Methomyl (technical grade) as Class IB: highly hazardous; Main Use: insecticide.|It was introduced, in 1966, as exptl insecticide-nematocide by EI Du Pont de nemours & Co ... under code number "Du Pont 1179", trade mark 'Lannate' & protected by US patent 3576834 & 3639633. ... following soil treatment it is taken up by roots & translocated ... this method is generally less effective than foliar treatment.|Nu-Bait III, produced by Griffin Corp, has been discontinued|An insecticide microcapsule consisting essentially of a core of methomyl surrounded by a cover of non-crosslinked, all aromatic polyurea. The polyurea is formed by dispersing a solution of methylene chloride, methomyl, and toluene-2,4-diisocyanate of at least 95% purity in aqueous medium creating a dispersion of liquid microspheres. The ratio of toluene-2,4-diisocyanate to methomyl is 1:4 to 3:1 by weight and the ratio of methylene chloride to methomyl is about 2:1 to 3:1 by weight. Hardening the liquid microspheres is achieved by adding an aqueous alkali to the dispersion with the ratio of aqueous alkali to toluene-2,4-diisocyanate being about 0.25:2 to 2:1 on a molar basis and removing the methylene chloride.

A REVERSE PHASE HIGH PRESSURE LIQUID CHROMATOGRAPHIC METHOD IS PRESENTED FOR THE SEPARATION & DETERMINATION OF RESIDUES OF METHOMYL ON VEGETABLES.|Determination of six N-methylcarbamates incl methomyl in vegetables and fruits by high performance liq chromatography is described.|Determination of N-methylcarbamate pesticides, incl methomyl, in well water by liq chromatography with post-column fluorescence derivatization is described. Mean recoveries for all 9 substances at the approx concn of 8 and 40 ppb are in excess of 95%.|A simple and specific method of determining methomyl residues in selected vegetables, grains, and soil is described. The method is based on the modification of a qualitative test for aldoxime and ketoxime methomyl is converted to oxime and hydroxylamine by alkali and acid treatment. An amount of 0.625 ppm methomyl can be determined in a 40 g sample of selected vegetables, grains, and soils.|For more Analytic Laboratory Methods (Complete) data for METHOMYL (11 total), please visit the HSDB record page.

A chemical ionization mass fragmentography method for determination of methomyl in biological samples was used to detect a peak concn of 1.61 ug/g in the blood of a female subject 6 hr after ingestion of 2.25 g.|A thin-layer chromatographic method with flame-ionization for the quantitative evaluation of methomyl (S-methyl N-(methylcarbamoyl)oxy)thioacetimidate) in serum and urine is described. Methomyl in biological fluids was separated and purified simply and rapidly by passing the samples through a Sep Pak C-18 silica cartridge, in contrast to the complicated pretreatment required in conventional methods. The detection limit was 0.07 ug in the spotted volume using Chromarod A with acetone-hexane (1:4, v/v) as the solvent system. The recoveries were 104.0% in serum, and 98.5% in urine. Further, the method showed good precision; the coefficient of variation was 2.4% in serum, and 4.0% in urine. The reproducibility was satisfactory and this method could be performed far more simply and rapidly than the conventional ones.

Agrochemicals -> Insecticides|INSECTICIDES