Metaldehyde

Crystalline powder

Crystals

In water, 200 mg/L at 17 °C /Polymer/

Moderately soluble in water, fairly soluble in toluene, readily soluble in methanol, very soluble in benzene and chloroform, insoluble in acetic acid, and slightly soluble in ethanol.

Insoluble in water, acetone, acetic acid, and carbon disulfide.

In toluene 530 mg/L at 20 °C, in methanol 1730 mg/L at 20 °C

In water, 222 mg/L at 20 °C

Vapor pressure is negligible at room temperature.

6.6X10+3 mPa (5.0X10-2 mm Hg) at 25 °C

Metaldehyde is a white-colored crystalline solid. It is insoluble in water. It is highly flammable and when ignited will give off irritating fumes. It may be toxic by ingestion and is very irritating to skin and eyes. It is used to make other chemicals.

Solid; [IUCLID] Formulated as granules, pellets, mini-pellets, meal, paste, and liquid; [Reference #1] Colorless or white solid; [Reference #2] White odorless powder; [Alfa Aesar MSDS]

Danger

H228: Flammable solid [Danger Flammable solids]；H301: Toxic if swallowed [Danger Acute toxicity, oral]；H361f: Suspected of damaging fertility [Warning Reproductive toxicity]；H412: Harmful to aquatic life with long lasting effects [Hazardous to the aquatic environment, long-term hazard]

P203, P210, P240, P241, P264, P270, P273, P280, P301+P316, P318, P321, P330, P370+P378, P405, and P501 (click each P-code to see the statement)

Danger

Chemical: 1,3,5,7-Tetroxocane, 2,4,6,8-tetramethyl-

Chemical: Metaldehyde

Commission Regulation (EC) No 33/2008

Metaldehyde is listed in the dataset of EPA Human Health Benchmarks for Pesticides under the Safe Drinking Water Act (40 eCFR 141)

2011/54/EU, Reg. (EU) 2018/1266, Reg. (EU) 2023/918, Reg. (EU) No 540/2011

Status: Active Update: 24-02-2020 https://echa.europa.eu/registration-dossier/-/registered-dossier/24890

Excerpt from ERG Guide 133 [Flammable Solids]:；Flammable/combustible material. May be ignited by friction, heat, sparks or flames. Some may burn rapidly with flare-burning effect. Powders, dusts, shavings, borings, turnings or cuttings may explode or burn with explosive violence. Substance may be transported in a molten form at a temperature that may be above its flash point. May re-ignite after fire is extinguished. (ERG, 2024)

· Flammable/combustible material.；· May be ignited by friction, heat, sparks or flames.；· Some may burn rapidly with flare-burning effect.；· Powders, dusts, shavings, borings, turnings or cuttings may explode or burn with explosive violence.；· Substance may be transported in a molten form at a temperature that may be above its flash point.；· May re-ignite after fire is extinguished.

Moderate when exposed to heat or flame; can react with oxidizing materials.

It is highly flammable and when ignited will give off irritating fumes.

The polymer is so flammable that it is used as a fuel.

Excerpt from ERG Guide 133 [Flammable Solids]:；Fire may produce irritating and/or toxic gases. Contact may cause burns to skin and eyes. Contact with molten substance may cause severe burns to skin and eyes. Runoff from fire control or dilution water may cause environmental contamination. (ERG, 2024)

· Fire may produce irritating and/or toxic gases.；· Contact may cause burns to skin and eyes.；· Contact with molten substance may cause severe burns to skin and eyes.；· Runoff from fire control or dilution water may cause environmental contamination.

Not irritating to skin and slightly irritating to eyes of rabbits; Neurological effects (ataxia, twitching, tremors, and hind-limb paralysis) observed in studies of dogs and rats; No increased susceptibility of fetuses seen in developmental toxicity and 2-generation reproduction studies of rats and rabbits; Atrophy of the testes and prostate observed in chronic oral study of dogs (LOAEL = 90 mg/kg/day); [Reference #1] Slowly hydrolyzed in acidic media (i.e., in the stomach) to acetaldehyde (the main toxicologically significant component) which is further oxidized to acetic acid; A skin, eye, and mucous membrane irritant; May be corrosive to eyes; Inhalation of fumes can cause CNS depression, convulsions, and coma; Interferes with reproductive process in rats; No evidence of teratogenicity, carcinogenicity, or mutagenicity; [Reference #2] Highly flammable; An irritant; Toxic by ingestion; [Alfa Aesar MSDS] See Polyacetaldehyde.

IPCS; Poisons Information Monograph 332: Metaldehyde (June, 1990). Poisons Information Monographs (PIM) are a global database with evaluated information on substances commonly involved in cases of poisoning.[Available from, as of October 9, 2009: http://www.inchem.org/pages/pims.html]

USEPA/Office of Pesticide Programs; Reregistration Eligibility Decision Document - Metaldehyde. OPP-2005-0231 (July 27, 2006). 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 October 7, 2009: http://www.epa.gov/pesticides/reregistration/status.htm]

Tolerances are established for residues of the molluscicide metaldehyde in or on food commodities, as follows: [Table#3512]

Metaldehyde products are currently labeled for many uses which are not being supported by the technical registrant. Only those uses that are supported by the registrant through development of required data have been assessed for this reregistration decision. The uses of metaldehyde that are being supported are: turf/dichondra, ornamentals, citrus, lettuce, cole crops and other leafy greens, tomato, strawberry, berries (including blackberry, blueberry, currant, elderberry, gooseberry, raspberries), and grass grown for seed, and artichoke. With the exception of the use on turf and dichondra, these uses of metaldehyde are eligible for reregistration, provided that the risk mitigation measures required by this RED are implemented, and the data submitted pursuant to the requirements identified in this RED are confirmatory. The IR-4 program of the U.S. Department of Agriculture, which develops residue data for minor and specialty crops, has done research on a number of additional uses for metaldehyde. At the current time, residue data for the use of metaldehyde on prickly pear cactus and watercress are in development. While these uses were included in the health effects and environmental risk assessments for metaldehyde, decisions on their registration have not been made for this RED.

As the federal pesticide law FIFRA directs, EPA is conducting a comprehensive review of older pesticides to consider their health and environmental effects and make decisions about their continued use. Under this pesticide reregistration program, EPA examines newer health and safety data for pesticide active ingredients initially registered before November 1, 1984, and determines whether the use of the pesticide does not pose unreasonable risk in accordance to newer saftey standards, such as those described in the Food Quality Protection Act of 1996. Metaldehyde is found on List A, which contains most pesticides that are used on foods and, hence, have a high potential for human exposure. List A consists of the 194 chemical cases (or 350 individual active ingredients) for which EPA issued registration standards prior to FIFRA '88. Case No: 0576; Pesticide type: insecticide (mulluscicide); Registration Standard Date: 12/25/88 PB89-161996; Case Status: OPP is reviewing data from the pesticide's producers regarding its human health and/or environmental effects, or OPP is determining the pesticide's eligibility for reregistration and developing the RED document.; Active ingredient (AI): metaldehyde; Data Call-in (DCI) Date(s): 10/13/95; AI Status: The producers of the pesticide have made commitments to conduct the studies and pay the fees required for reregistration, and are meeting those commitments in a timely manner.

METALDEHYDE is an ether derivative. The ether being relatively unreactive. Flammable and/or toxic gases are generated by the combination of alcohols with alkali metals, nitrides, and strong reducing agents. They react with oxoacids and carboxylic acids to form esters plus water. Oxidizing agents convert alcohols to aldehydes or ketones.

Excerpt from ERG Guide 133 [Flammable Solids]:；SMALL FIRE: Dry chemical, CO2, sand, earth, water spray or regular foam.；LARGE FIRE: Water spray, fog or regular foam. If it can be done safely, move undamaged containers away from the area around the fire.；FIRE INVOLVING METAL PIGMENTS OR PASTES (E.G. "ALUMINUM PASTE"): Aluminum Paste fires should be treated as a combustible metal fire. Use DRY sand, graphite powder, dry sodium chloride-based extinguishers or class D extinguishers. Also, see ERG Guide 170.；FIRE INVOLVING TANKS, RAIL TANK CARS OR HIGHWAY TANKS: Cool containers with flooding quantities of water until well after fire is out. For massive fire, use unmanned master stream devices or monitor nozzles; if this is impossible, withdraw from area and let fire burn. Withdraw immediately in case of rising sound from venting safety devices or discoloration of tank. ALWAYS stay away from tanks in direct contact with flames. (ERG, 2024)

· CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper not available or no answer, refer to appropriate telephone number listed on the inside back cover.；· Keep unauthorized personnel away.；· Stay upwind, uphill and/or upstream.

· ELIMINATE all ignition sources (no smoking, flares, sparks or flames) from immediate area.；· Do not touch or walk through spilled material.；Small Dry Spill；· With clean shovel, place material into clean, dry container and cover loosely; move containers from spill area.；Large Spill；· Wet down with water and dike for later disposal.；· Prevent entry into waterways, sewers, basements or confined areas.

Excerpt from ERG Guide 133 [Flammable Solids]:；Refer to the "General First Aid" section. Specific First Aid: Removal of solidified molten material from skin requires medical assistance. (ERG, 2024)

General First Aid:；· Call 911 or emergency medical service.；· Ensure that medical personnel are aware of the material(s) involved, take precautions to protect themselves and avoid contamination.；· Move victim to fresh air if it can be done safely.；· Administer oxygen if breathing is difficult.；· If victim is not breathing:；-- DO NOT perform mouth-to-mouth resuscitation; the victim may have ingested or inhaled the substance.；-- If equipped and pulse detected, wash face and mouth, then give artificial respiration using a proper respiratory medical device (bag-valve mask, pocket mask equipped with a one-way valve or other device).；-- If no pulse detected or no respiratory medical device available, provide continuous compressions. Conduct a pulse check every two minutes or monitor for any signs of spontaneous respirations.；· Remove and isolate contaminated clothing and shoes.；· For minor skin contact, avoid spreading material on unaffected skin.；· In case of contact with substance, remove immediately by flushing skin or eyes with running water for at least 20 minutes.；· For severe burns, immediate medical attention is required.；· Effects of exposure (inhalation, ingestion, or skin contact) to substance may be delayed.；· Keep victim calm and warm.；· Keep victim under observation.；· For further assistance, contact your local Poison Control Center.；· Note: Basic Life Support (BLS) and Advanced Life Support (ALS) should be done by trained professionals.；Specific First Aid:；· Removal of solidified molten material from skin requires medical assistance.

Regulated by IATA.

Store in cool place to minimize sublimation. Avoid prolonged storage.

Store with care, containers of soldered tinplate are unsuitable.

Storage should be under lock and key, secure from access by children and other unauthorized persons. Metaldehyde is flammable; store in a cool place away from sources of heat and ignition. Avoid prolonged storage.

Safe Storage of Pesticides. Always store pesticides in their original containers, complete with labels that list ingredients, directions for use, and first aid steps in case of accidental poisoning. Never store pesticides in cabinets with or near food, animal feed, or medical supplies. Do not store pesticides in places where flooding is possible or in places where they might spill or leak into wells, drains, ground water, or surface water.

SRP: Wastewater from contaminant suppression, cleaning of protective clothing/equipment, or contaminated sites should be contained and evaluated for subject chemical or decomposition product concentrations. Concentrations shall be lower than applicable environmental discharge or disposal criteria. Alternatively, pretreatment and/or discharge to a permitted wastewater treatment facility is acceptable only after review by the governing authority and assurance that "pass through" violations will not occur. Due consideration shall be given to remediation worker exposure (inhalation, dermal and ingestion) as well as fate during treatment, transfer and disposal. If it is not practicable to manage the chemical in this fashion, it must be evaluated in accordance with EPA 40 CFR Part 261, specifically Subpart B, in order to determine the appropriate local, state and federal requirements for disposal.

Spillage of liquid formulations should be contained with adsorbent material. This material, or spillage of dry formulations, should be collected and burned or buried in a deep pit. Residual contamination should be removed from the spillage site by washing with water and detergent.

If a spill occurs, clean it up promptly. Don't wash it away. Instead, sprinkle the spill with sawdust, vermiculite, or kitty litter. Sweep it into a plastic garbage bag, and dispose of it as directed on the pesticide product label.

After Applying a Pesticide, Indoors or Outdoors. To remove pesticide residues, use a bucket to rinse tools or equipment three times, including any containers or utensils that you used when mixing the pesticide. Then pour the rinsewater into the pesticide sprayer and reuse the solution by applying it according to the pesticide product label directions. After applying any pesticide wash your hands and any other parts of your body that may have come in contact with the pesticide. To prevent tracking pesticides inside, remove or rinse your boots or shoes before entering your home. Wash any clothes that have been exposed to a lot of pesticide separately from your regular wash.

Excerpt from ERG Guide 133 [Flammable Solids]:；ELIMINATE all ignition sources (no smoking, flares, sparks or flames) from immediate area. Do not touch or walk through spilled material.；SMALL DRY SPILL: With clean shovel, place material into clean, dry container and cover loosely; move containers from spill area.；LARGE SPILL: Wet down with water and dike for later disposal. Prevent entry into waterways, sewers, basements or confined areas. (ERG, 2024)

SRP: Criteria for land treatment or burial (sanitary landfill) disposal practices are subject to significant revision. Prior to implementing land disposal of waste residue (including waste sludge), consult with environmental regulatory agencies for guidance on acceptable disposal practices.

Do not discharge effluent containing this product into lakes, streams, ponds, estuaries, oceans, or other waters unless in accordance with the requirements of a National Pollution Discharge Elimination System (NPDES) permit and the permitting authority has been notified in writing prior to discharge. Do not discharge effluent containing this product to sewer systems without previously notifying the local sewage treatment plant authority. For guidance contact your State Water Board or Regional Office of the EPA.

Care must be taken to ensure that water sources are not contaminated. If the empty containers are burned, care must be taken to ensure that flammable residues do not cause an uncontrolled reaction. Containers may be decontaminated ..., but decontaminated containers must not be used for the transportation of food or drink.

Metaldehyde is flammable; where burning is recommended care must be taken to ensure that the operation remains controlled at all times.

For more Disposal Methods (Complete) data for Metaldehyde (6 total), please visit the HSDB record page.

SRP: Contaminated protective clothing should be segregated in a manner that results in no direct personal contact by personnel who handle, dispose of, or clean the clothing. Quality assurance procedures to confirm the efficacy of the cleaning procedures should be implemented prior to the decontaminated protective clothing being returned for reuse by the workers. Contaminated clothing (including shoes/socks) should not be taken home at end of shift, but should remain at employee's place of work for cleaning.

If material not on fire and not involved in fire: Keep sparks, flames, and other sources of ignition away. Keep material out of water sources and sewers.

Personnel protection: Avoid breathing dusts and fumes from burning material. Avoid bodily contact with the material. ... Do not handle broken packages unless wearing appropriate personal protective equipment. Wash away any material which may have contacted the body with copious amounts of water or soap and water.

If you suspect your pet has eaten metaldehyde slug bait, consider seeking veterinary care as soon as possible. Signs of poisoning may occur within a few minutes or up to three hours after ingestion. Timely treatment could save your pet's life.

For more Preventive Measures (Complete) data for Metaldehyde (20 total), please visit the HSDB record page.

Excerpt from ERG Guide 133 [Flammable Solids]:；IMMEDIATE PRECAUTIONARY MEASURE: Isolate spill or leak area for at least 25 meters (75 feet) in all directions.；LARGE SPILL: Consider initial downwind evacuation for at least 100 meters (330 feet).；FIRE: If tank, rail tank car or highway tank 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, 2024)

Immediate precautionary measure；· Isolate spill or leak area for at least 25 meters (75 feet) in all directions.；Large Spill；· Consider initial downwind evacuation for at least 100 meters (330 feet).；Fire；· If tank, rail tank car or highway tank 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.

In mice intraperitoneal administration of 10 mg/kg bw diazepam or 0.5 mg/kg clonidine hydrochloride decreased the toxicity of an oral dose of 100 mg metaldehyde/kg bw administered 20 min previously. A dose of 0.5 mg diazepam/kg bw was without protective effect.

LC50; Species: /Lepornis macrochis/ (bluegil); Concentration: 10 ug/L for 96 hr /Conditions of bioassay not specified in source/

LC50; Species: /Oncorynchus sp/ (Rainbow trout); Concentration: 69 mg/L 96 hr /Conditions of bioassay not specified in source/

LC50; Species: Daphnia (water flea); Concentration: >77.66 mg/L for 48 hr /Conditions of bioassay not specified in source/

LD50; Species: /Coturnix japonica/ (Japanese quail) single oral dose 181 mg/kg

TERRESTRIAL FATE: Based on a classification scheme(1), a measured Koc value of 240(2) indicates that metaldehyde is expected to have moderate mobility in soil(SRC). Volatilization of metaldehyde from moist soil surfaces is expected to be an important fate process(SRC) given an estimated Henry's Law constant of 5.2X10-5 atm-cu m/mole(SRC), derived from its vapor pressure, 5.0X10-2 mm Hg(2), and water solubility, 2.22X10+2 mg/L(2). Metaldehyde is not expected to volatilize from dry soil surfaces(SRC) based upon its vapor pressure(2). The results of a laboratory volatility study suggest that volatilization losses from soil surfaces will be minor(3). In a field study, 6% metaldehyde pellets were broadcast at the rate of 4 kg product/ha in a rice paddy ecosystem(4). Paddy soil samples collected 3 to 14 days after application had metaldehyde residue concentrations ranging from 0.053 to 0.127 mg/kg, reaching a peak at 0.127 mg/kg 14 days after application(4). Metaldehyde residue was below the minimum detection limit of 0.016 mg/kg 22 days after application(4). A reported half-life of approximately 2 months for metaldehyde in soil(3) suggests that biodegradation is not an important environmental fate process in soil(SRC). In soil, microbiological decomposition of metaldehyde to carbon dioxide and water occurs(2).

AQUATIC FATE: Based on a classification scheme(1), a measured Koc value of 240(2) indicates that metaldehyde is not expected to adsorb to suspended solids and sediment(SRC). Volatilization from water surfaces is expected(3) based upon an estimated Henry's Law constant of 5.2X10-5 atm-cu m/mole(SRC), derived from its vapor pressure, 5.0X10-2 mm Hg(2), and water solubility, 2.22X10+2 mg/L(2). Using this Henry's Law constant and an estimation method(3), volatilization half-lives for a model river and model lake are 26 hours and 12 days, respectively(SRC). In a field study, 6% metaldehyde pellets were broadcast at the rate of 4 kg product/ha in a rice paddy ecosystem(4). Paddy water samples collected 1 to 3 days after application had metaldehyde residue concentrations of 1.58 to 1.47 mg/L(4). Residues could be detected only up to 9 days after application, with its degradation pattern following pseudo first-order kinetics showing a half-life of 0.27 days(4). According to a classification scheme(5), an estimated BCF of 3.2(SRC), from its log Kow(2) and a regression-derived equation(6), suggests the potential for bioconcentration in aquatic organisms is low. Utilizing the Japanese MITI test, a 0% of theoretical BOD in four weeks(7) suggests that biodegradation is not an important environmental fate process in water(SRC).

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), metaldehyde, which has a vapor pressure of 5.0X10-2 mm Hg at 25 °C(2), is expected to exist solely as a vapor in the ambient atmosphere. Vapor-phase metaldehyde 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 13 hours(SRC), calculated from its rate constant of 2.9X10-11 cu cm/molecule-sec at 25 °C(SRC) that was derived using a structure estimation method(3). Metaldehyde does not contain chromophores that absorb at wavelengths >290 nm(4) and therefore is not expected to be susceptible to direct photolysis by sunlight(SRC).

The toxicologically active substance in metaldehyde intoxication is mainly the degradation product acetaldehyde; other toxic products are probably also formed. Acetaldehyde acts as a releasing factor for 5-hydroxytryptamine (5-HT) and noradrenaline (NA). It also competitively inhibits biogenic amine oxidation which, in turn, decreases 5-hydroxyindoleacetic acid (5-HIAA), a metabolite of 5-HT by competitively inhibiting 5-HT-oxidation. Acetaldehyde also increases monoamine oxidase activity and decreases central serotonin levels. (L1782)

/BIRDS and MAMMALS/ A survey of mortality in hedgehogs (Erinaceus europaeus) was carried out between July 1976 and November 1986. Of the 74 examined, 35 (47.3 per cent) were road casualties ... Metaldehyde poisoning was diagnosed in three animals.

/BIRDS and MAMMALS/ Available data on the acute toxicity for terrestrial animals indicate that metaldehyde is moderately toxic to mammals and slightly to moderately toxic to birds on an acute exposure basis. For the chronic assessments, parental systemic toxicity and toxicity to offspring are identified as the endpoint for mammalian wildlife. For birds, the chronic endpoint is based on reproductive effects (reductions in the ratios of number hatched to eggs laid, to eggs set, and to live embryos; and reduction in the ratio of hatchling survival to eggs set), as observed in a study conducted with mallard ducks.；Table: Metaldehyde Toxicity Values for Terrestrial Organisms [Table#3511]

/AQUATIC SPECIES/ Molluscicide with stomach and contact action. Contact with the foot makes the mollusk torpid, and induces an increased secretion of mucus, leading to dehydration.

/FIELD STUDIES/ Over two years, six consecutive field experiments were done in which the chemical molluscicide metaldehyde and the nematode biocontrol agent Phasmarhabditis hermaphrodita (Schneider) were applied at the standard field rates to replicated mini-plots successively planted with lettuce, Brussels sprouts, leaf beet, and cabbage, to compare the effectiveness of different treatments in reducing slug damage to the crops. Soil samples from each plot were taken prior to the start of the experiments, and then monthly, to assess the populations of slugs, snails, earthworms, nematodes, acarids and collembolans. The experiments were done on the same site and each plot received the same treatment in the six experiments. The six treatments were: (1) untreated controls, (2) metaldehyde pellets, (3 and 4) nematodes applied to the planted area 3 days prior to planting without or with previous application of cow manure slurry, (5) nematodes applied to the area surrounding the planted area 3 days prior to planting, and (6) nematodes applied to the planted area once (only in the first of the six consecutive experiments). Only the metaldehyde treatment and the nematodes applied to the planted area at the beginning of each experiment without previous application of manure significantly reduced slug damage to the plants, and only metaldehyde reduced the number of slugs contaminating the harvested plants. The numbers of slugs, snails and earthworms in soil samples were compared among the six treatments tested: with respect to the untreated controls, the numbers of Deroceras reticulatum (Muller) were significantly affected only in the metaldehyde plots, and the numbers of Arion ater L only in the plots treated with nematodes applied to the planted area 3 days prior to planting without previous application of manure; numbers of snails (Ponentina ponentina (Morelet) and Oxychilus helveticus (Blum)) were not affected by the treatment. The total numbers of all earthworm species an

Ingestion is the most common route of metaldehyde poisoning. One to three hours after ingestion the following can occur: severe abdominal pain, nausea, salivation, vomiting, facial flushing, gastroenteritis, diarrhoea, metabolic acidosis, a marked rise in body temperature, drowsiness, convulsions, muscular rigidity, spasms, rhabdomyolysis and coma. Pulse and respiratory rate become progressively slower. Liver and kidney injury occurs at a later stage. Metaldehyde fumes may cause somnolence, uncoordinated movements, nausea, dizziness, CNS-depression, convulsions, and coma. Metaldehyde is also irritant to eyes and skin. (L1787)

/SIGNS AND SYMPTOMS/ Symptoms generally occur within 3 hours (although they have been delayed up to 48 hours and include salivation, lethargy, abdominal pain, nausea, vomiting, and diarrhea, progressing to seizures, hyperthermia, comas, and death. inhalation produces mucous membrane irritation, and inhaling pyrolized metaldehyde has caused noncardiogenic pulmonary edema. Memory loss and cognitive dysfunction have been reported after severe poisoning.

/SIGNS AND SYMPTOMS/ Potential symptoms of overexposure by ingestion are severe abdominal pain, nausea, vomiting, diarrhea, convulsions, coma.[The Merck Index, Fourteenth Edition (2006)

/SIGNS AND SYMPTOMS/ The following relationships between clinical effects and ingested dose have been suggested: salivation, facial flushing, fever, abdominal cramps, nausea, and vomiting from a "few" mg/kg; drowsiness, tachycardia, spasms, irritability, salivation, abdominal cramps, facial flushing, and nausea from up to 50 mg/kg; ataxia and increased muscle tone from 50-100 mg/kg, convulsions, tremor, and hyperreflexia from 100-200 mg/kg; and coma and death from about 400 mg/kg.

/SIGNS AND SYMPTOMS/ Several incidents of metaldehyde exposure are reported in literature. Ingestion of slug-bait pellets by children accounts for the majority of the incidents reported in the United States of America between 1966-1980. In Europe, human poisonings are also associated with voluntary ingestion of tablets intended for use as fuel. Appearance of symptoms might be delayed a few hours after ingestion. Survivors of severe poisoning showed loss of memory which lasted for up to a year. Laboratory findings included acid urine despite alkali therapy and elevated serum transaminase activities. At autopsy, the main findings were fatty degeneration with zonal necrosis of the liver and swelling and desquamation of the renal tubular epithelium.

For more Human Toxicity Excerpts (Complete) data for Metaldehyde (19 total), please visit the HSDB record page.

Chemical: 1,3,5,7-Tetroxocane, 2,4,6,8-tetramethyl-

Chemical: Metaldehyde

Commission Regulation (EC) No 33/2008

Metaldehyde is listed in the dataset of EPA Human Health Benchmarks for Pesticides under the Safe Drinking Water Act (40 eCFR 141)

2011/54/EU, Reg. (EU) 2018/1266, Reg. (EU) 2023/918, Reg. (EU) No 540/2011

Status: Active Update: 24-02-2020 https://echa.europa.eu/registration-dossier/-/registered-dossier/24890

Tolerances are established for residues of the molluscicide metaldehyde in or on food commodities, as follows: [Table#3512]

Metaldehyde products are currently labeled for many uses which are not being supported by the technical registrant. Only those uses that are supported by the registrant through development of required data have been assessed for this reregistration decision. The uses of metaldehyde that are being supported are: turf/dichondra, ornamentals, citrus, lettuce, cole crops and other leafy greens, tomato, strawberry, berries (including blackberry, blueberry, currant, elderberry, gooseberry, raspberries), and grass grown for seed, and artichoke. With the exception of the use on turf and dichondra, these uses of metaldehyde are eligible for reregistration, provided that the risk mitigation measures required by this RED are implemented, and the data submitted pursuant to the requirements identified in this RED are confirmatory. The IR-4 program of the U.S. Department of Agriculture, which develops residue data for minor and specialty crops, has done research on a number of additional uses for metaldehyde. At the current time, residue data for the use of metaldehyde on prickly pear cactus and watercress are in development. While these uses were included in the health effects and environmental risk assessments for metaldehyde, decisions on their registration have not been made for this RED.

As the federal pesticide law FIFRA directs, EPA is conducting a comprehensive review of older pesticides to consider their health and environmental effects and make decisions about their continued use. Under this pesticide reregistration program, EPA examines newer health and safety data for pesticide active ingredients initially registered before November 1, 1984, and determines whether the use of the pesticide does not pose unreasonable risk in accordance to newer saftey standards, such as those described in the Food Quality Protection Act of 1996. Metaldehyde is found on List A, which contains most pesticides that are used on foods and, hence, have a high potential for human exposure. List A consists of the 194 chemical cases (or 350 individual active ingredients) for which EPA issued registration standards prior to FIFRA '88. Case No: 0576; Pesticide type: insecticide (mulluscicide); Registration Standard Date: 12/25/88 PB89-161996; Case Status: OPP is reviewing data from the pesticide's producers regarding its human health and/or environmental effects, or OPP is determining the pesticide's eligibility for reregistration and developing the RED document.; Active ingredient (AI): metaldehyde; Data Call-in (DCI) Date(s): 10/13/95; AI Status: The producers of the pesticide have made commitments to conduct the studies and pay the fees required for reregistration, and are meeting those commitments in a timely manner.

The toxicologically active substance in metaldehyde intoxication is mainly the degradation product acetaldehyde, which is formed at a low pH in the stomach. Other toxic products are probably also formed. Acetaldehyde acts as a releasing factor for 5-hydroxytryptamine (5-HT) and noradrenaline (NA). It also competitively inhibits biogenic amine oxidation which, in turn, decreases 5-hydroxyindoleacetic acid (5-HIAA), a metabolite of 5-HT by competitively inhibiting 5-HT-oxidation. Acetaldehyde also increases monoamine oxidase activity and decreases central serotonin levels ...

Its pesticidal action is due to contact with the foot of the mollusk, making it torpid and increasing the secretion of mucus leading to dehydration.

Metaldehyde slowly hydrolyzes to acetaldehyde in acid solutions (i.e., in the stomach). Acetaldehyde is then oxidized to acetic acid. Acetaldehyde was not found in plasma and urine of metaldehyde treated dogs.

Ingestion of about 100 to 150 mg/kg of metaldehyde led to peak serum levels of metaldehyde (120 ug/mL) 35 hr after ingestion & urine levels of 53 ug/mL in 14 hr. Acetaldehyde levels in the serum were <1.0 ug/mL.

Metaldehyde is absorbed from the gastrointestinal tract and may be absorbed from the skin or lungs. Metaldehyde slowly hydrolyses to acetaldehyde in acid solutions (i.e., in the stomach). Acetaldehyde is then oxidized to acetic acid. (L1787)

Metaldehyde is readily absorbed from GI tract, probably as different sized fragments of acetaldehyde polymer ... These substances readily cross blood-brain barrier, as evidenced by their effect on level of consciousness.

Metaldehyde was found in the plasma & urine of dogs given a single oral dose of 600 mg/kg. The urinary excretion of metaldehyde was <1% of the dose.

Used for control of snails in seed crops, turf, ornamentals, berries, citrus, vegetables, and other crops; [Reference #1] Used for synthesis in the chemical industry, as odor agent, and as pesticide; [IUCLID] Used as molluscicide, solid fuel for small heaters (alcohol replacement), and fire starter; [Reference #2]

Farming (Pesticides) [Category: Industry]

For metaldehyde (USEPA/OPP Pesticide Code: 053001) ACTIVE products with label matches. /SRP: Registered for use in the U.S. but approved pesticide uses may change periodically and so federal, state and local authorities must be consulted for currently approved uses./

Metaldehyde is a molluscicide used to control snails and slugs on a wide variety of sites, including turf, ornamentals, berries, citrus, and vegetables.

In compressed form as a fuel instead of alcohol; molluscicide. /Polymer/

Metaldehyde is used as a pesticide against slugs, snails, and other gastropods, it is also used in tablets as a solid fuel for small heaters, and as fire-starter. (L1782)

Metaldehyde is obtained in addition to large amounts of paraldehyde during polymerization of acetaldehyde in the presence of HBr and alkaline earth metal bromides, such as CaBr2, at temperatures below 0 °C. However, yields are scarcely higher than 8%. Yields of 14 - 20% have been reported when working in the presence of 7 - 15% of an aliphatic or cyclic ether at 0 - 20 °C. Insoluble metaldehyde is filtered out. Acetaldehyde is then distilled from the filtrate following depolymerization of the paraldehyde and is returned to the polymerization. Recycling of the large amounts of acetaldehyde results in losses that increase the process costs.

Prepd by polymerization of acetaldehyde in presence of hydrochloric acid, sulfuric acid @ low temp: Kekule, Zincke, Ann 162, 125 (1872); in presence of pyridine and hydrogen bromide: Wilder, US patent 2,426,961 (1947 to Publicker Ind).

Corry's Slug, Snail & Insect Killer, Get-A-Bug Snail, Slug & Insect Killer : Active ingredients 2.0%Metaldehyde, 5.0% Carbaryl

Bug-Geta Snail & Slug Pellets: Active ingredient 3.25% Metaldehyde

Durham Metaldehyde Granules 3.5: Active ingredient 3.5% Metaldehyde

Corry's Liquid Slug & Snail Control, Deadline Bullets, Deadline M-PS Mini-Pellets!, Metaldehyde 4 Bait, Metarex 4% Snail And Slug Bait: Active ingredient 4.0% Metaldehyde

For more Formulations/Preparations (Complete) data for Metaldehyde (29 total), please visit the HSDB record page.

Information on 12 consumer products that contain Metaldehyde [BSI:ISO] in the following categories is provided:；• Pesticides

Information on 4 consumer products that contain Metaldehyde in the following categories is provided:；• Pesticides

Molluscicides

Environmental transformation -> Pesticides (parent, predecessor)