Metolachlor

Pesticides

Pesticide -> EPA IRIS

Herbicides

Active substance -> EU Pesticides database: Not approved

Pesticides -> Herbicides, Chloracetanilide

Pesticide

log Kow = 3.13

2.9

3.09

1.12 (USCG, 1999) - Denser than water; will sink

1.12 g/cu cm at 20 °C

1.12 g/cm³

Colorless liquid

Colorless to tan liquid

Miscible with benzene, toluene, ethanol, acetone, xylene, hexane, dimethylformamide, dichloroethane, cyclohexanone, methanol, octanol, and dichloromethane. Insoluble in ethylene glycol, propylene glycol, and petroleum ether.

Soluble in most organic solvents.

In water, 530 mg/L at 20 °C

Solubility in water, mg/l at 25 °C: 488

greater than 230 °F (USCG, 1999)

Flashpoint of Dual 8E is 200 °F (Closed cup)

190 °C

212 °F at 0.001 mmHg (USCG, 1999)

BP: 100 °C at 0.001 mm Hg

-62.1 °C

-62.1 °C

0.0000314 [mmHg]

3.14X10-5 mm Hg at 25 °C

Vapor pressure, Pa at 25 °C: 0.0042

This chemical does not meet GHS hazard criteria for 4.2% (3 of 71) of reports.

Danger

H317 (94.4%): May cause an allergic skin reaction [Warning Sensitization, Skin]

P260, P261, P271, P272, P273, P280, P284, P302+P352, P304+P340, P316, P320, P321, P333+P317, P362+P364, P391, P403+P233, P405, and P501 (click each P-code to see the statement)

Aggregated GHS information provided per 71 reports by companies from 5 notifications to the ECHA C&L Inventory. Each notification may be associated with multiple companies.

Danger

2002/2076

Metolachlor: Does not have an individual approval but may be used under an appropriate group standard

The New Jersey Worker and Community Right to Know Act requires public and private employers to provide information about hazardous substances at their workplaces. (N.J.S.A. 34:5A-1 et. seq.)

Classified as 'slightly toxic, metolachlor is an pre-emergent herbicide with an oral LD50 of 2780 mg/kg. [EXTOXNET] Methemoglobinemia has been reported after poisoning by ingestion. [HSDB] No listed effects of short-term or long-term exposure; [ICSC] A strong skin sensitizer; Increased incidence of liver tumors in female rats; No developmental toxicity; Reduced pup weights in reproductive study with no toxicity in parental animals; [Krieger, p. 1762-3]

USEPA/Office of Pesticide Programs; Reregistration Eligibility Decision Document - Metolachlor, EPA 738-R-95-006 (April 1995). 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 January 31, 2012: http://www.epa.gov/pesticides/reregistration/status.htm]

Tolerances are established for the combined residues (free and bound) of the herbicide metolachlor, 2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide, and its metabolites, determined as the derivatives, 2-[(2-ethyl-6-methylphenyl)amino]-1-propanol and 4-(2-ethyl-6-methylphenyl)-2-hydroxy-5-methyl-3-morpholinone, each expressed as the parent compound in the following raw agricultural commodities: [Table#6198]

Tolerances are established for residues of S-metolachlor, including its metabolites and degradates, in or on the commodity(s), as defined. Compliance with the tolerance levels specified in the following table below is to be determined by measuring only the sum of free and bound S-metolachlor, S-2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide, its R-enantiomer, and its metabolites, determined as the derivatives, 2-(2-ethyl-6-methylphenyl)amino-1-propanol and 4-(2-ethyl-6-methylphenyl)-2-hydroxy-5-methyl-3-morpholinone, calculated as the stoichiometric equivalent of S-metolachlor, in or on the commodity. /S-Metolachlor/ [Table#6199]

Tolerances with regional registration as defined in 180.1(l) are established for the combined residues (free and bound) of the herbicide metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide] and its metabolites, determined as the derivatives, 2-[2-ethyl-6-methylphenyl)amino]-1-propanol and 4-(2-ethyl-6-methylphenyl)-2-hydroxy-5-methyl-3-morpholinone, each expressed as the parent compound, in or on the following raw agricultural commodities: [Table#6200]

Tolerances with regional registration are established for residues of S-metolachlor, including its metabolites and degradates, in or on the commodities identified in the following table below. Compliance with the tolerance levels specified in the following table below is to be determined by measuring only the sum of free and bound S-metolachlor, S-2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide, its R-enantiomer, and its metabolites, determined as the derivatives, 2-(2-ethyl-6-methylphenyl)amino-1-propanol and 4-(2-ethyl-6-methylphenyl)-2-hydroxy-5-methyl-3-morpholinone, calculated as the stoichiometric equivalent of S-metolachlor, in or on the commodity. /S-Metolachlor/ [Table#6201]

For more FIFRA Requirements (Complete) data for METOLACHLOR (8 total), please visit the HSDB record page.

Fire Extinguishing Agents: Dry chemical, alcohol foam or carbon dioxide (USCG, 1999)

Use dry sand, alcohol-resistant foam, carbon dioxide.

Fresh air, rest.

Rinse and then wash skin with water and soap.

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

Give one or two glasses of water to drink. Refer for medical attention .

Dry sand, alcohol-resistant foam, carbon dioxide.

... Use dry chemical, carbon dioxide, or alcohol foam extinguishers. ...

Wear full protective clothing and self-contained breathing apparatus. Evacuate nonessential personnel from the area to prevent human exposure to fire, smoke, fumes or products of combustion. Prevent use of contaminated buildings, area, and equipment until decontaminated. Stay upwind. Minimize runoff. /Me-Too-Lachlor Herbicide/

Do not contaminate water, food or feed by storage ... Keep container closed to prevent spills and contamination. Store in original container. /Me-Too-Lachlor Herbicide/

Store above -30 °F.

Store in tightly closed containers in a cool, well ventilated area away from oxidizers. Where possible, automatically pump liquid from drums or other storage containers to porcess containers.

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. /Residential users/

... Remove all ignition sources. Ventilate area of spill or leak. Absorb liquids in vermiculite, dry sand, earth, peat, carbon, or a similar material and deposit in sealed containers. Keep this chemical out of a confined space such as a sewer, because of the possibility of an explosion, unless the sewer is designed to prevent the build-up of explosive concentrations. ...

Numerous pesticides were monitored in surface waters in agricultural areas. Atrazine, alachlor, metolachlor, cyanazine, metribuzin, carbofuran, linuron, and simazine were found in the influent to three water treatment plants in storm runoff following their application. Studies at these plants, together with bench-scale studies, demonstrated poor control by conventional treatment processes. The relatively high adsorption capacities of these agrichemicals indicate that granular activated carbon can be cost effective for their control. Powered activated carbon applied at taste and odor control doses can also be effective if moderate percent removal is required.

For small spills, cover the spill with an absorbent material such as pet litter. Sweep up and place in an approved chemical container. Wash the spill area with water containing a strong detergent, absorb with pet litter or other absorbent material, sweep up and place in a chemical container. Seal the container and handle in an approved manner. Flush the area with water to remove any residue. Do not allow wash water to contaminate water supplies. /Me-Too-Lachlor Herbicide/

Large spills should be dammed-off and pumped into containers; soak up remainder with absorbent material and dispose of in accordance with local regulations.

For more Cleanup Methods (Complete) data for METOLACHLOR (7 total), please visit the HSDB record page.

SRP: The most favorable course of action is to use an alternative chemical product with less inherent propensity for occupational harm/injury/toxicity 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 and plant life; and conformance with environmental and public health regulations.

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.

Must be disposed of by special means, e.g., suitable incineration, in accordance with local regulations.

Group I Containers: Combustible containers from organic or metallo-organic pesticides (except organic mercury, lead, cadmium, or arsenic compounds) should be disposed of in pesticide incinerators or in specified landfill sites. /Organic or metallo-organic pesticides/

For more Disposal Methods (Complete) data for METOLACHLOR (8 total), please visit the HSDB record page.

Do NOT let this chemical enter the environment. Collect leaking and spilled liquid in covered containers as far as possible. Then store and dispose of according to local regulations. Personal protection: P2 filter respirator for harmful particles.

Use this product only in accordance with its labeling and with the Worker Protection Standard, 40 CFR part 170. /Me-Too-Lachlor Herbicide/

For terrestrial uses, do not apply directly to water, to areas where surface water is present or to intertidal areas below the mean high water mark. /Me-Too-Lachlor Herbicide/

Do not apply this product in a way that will contact workers or other persons, either directly or through drift. Only protected handlers may be in the area during application. /Me-Too-Lachlor Herbicide/

Do not enter or allow worker entry into treated areas during the restricted entry interval (REI) of 24 hours. Exception: If the product is soil-injected or soil-incorporated, the Worker Protection Standard, under certain circumstances, allows workers to enter the treated area if there will be no contact with anything that has been treated. /Me-Too-Lachlor Herbicide/

For more Preventive Measures (Complete) data for METOLACHLOR (15 total), please visit the HSDB record page.

Consider gastric lavage, as well was dilution with milk or water after ingestion. Administer charcoal as a slurry following ingestion; however, activated charcoal should not be given to patients ingesting strong acidic or basic caustic chemicals. In case of inhalation, move patient to fresh air. Monitor for respiratory distress. If cough or difficulty breathing develops, evaluate for respiratory tract irritation, bronchitis, or pneumonitis. Administer oxygen and assist ventilation as required. Treat bronchospasm with inhaled beta2 agonist and oral or parenteral corticosteroids. Irrigate exposed eyes with copious amounts of room temperature water for at least 15 minutes. Following dermal exposure, remove contaminated clothing and wash exposed area thoroughly with soap and water. Treat dermal irritation or burns with standard topical therapy. Patients developing dermal hypersensitivity reactions may require treatment with systemic or topical corticosteroids or antihistamines. Administer symptomatic treatment as necessary. (T36)

The reproductive toxicity of a mixture of 5 pesticides (alachlor, atrazine, cyanazin, metolachlor, and metribuzin) and one fertilizer (ammonium nitrate) was evaluated in Swiss mice using the continuous breeding protocol. These chemicals and their relative concn in the stock mixture were selected on the basis of groundwater survey data from Iowa. Mice received the mixture in the drinking water at 0X, 1X, 10X and 100X, where 1X was the median concn of each component as determined by the surveys. F0 mice were fertile throughout 18 weeks exposure. mixture did not adversely affect reproductive competence, F0 body weight, food or water consumption, organ weights, or sperm parameters at necropsy. No treatment related clinical signs were noted. F1 preweaning growth and maturation were unaffected by mixture. No treatment related clinical signs or adverse effect of mixture on F1 reproductive competence, food and water consumption, male or female body weight, or selected male and female organ weights, sperm parameters, vaginal cytology, or histology of selected organs was observed. In summary, exposure to mixture in the drinking water at dose levels as high as 100X the median concn of the components in contaminated groundwater did not cause clearcut generalized or reproductive toxicity in either the F0 or F1 generation of Swiss mice.

Male Fischer 344 rats and female B6C3F1 mice were each exposed through their drinking water to a mixture of pesticides and ammonium nitrate that simulated contaminated groundwater in California (California Chemical Mixture). Exposures were for 71 or 91 days, respectively. In addition, B6C3F1 female mice were exposed for 91 days to another pesticide and ammonium nitrate mixture (Iowa Chemical Mixture) through their drinking water. The spleen were removed from the animals, and the splenocytes were cultured for analyses of sister chromatid exchange, chromosome aberrations, and micronuclei in cytochalasin B induced binucleate cells. A concn related increase in sister chromatid exchanges was found in the splenocytes of the rat at the 1X, 10X and 100X levels of the California Chemical Mixture and at the 100X concn of the California Chemical Mixture in the mouse. There were no other consistent cytogenetic effects observed with the California Chemical Mixture, and no statistically significant cytogenetic damage was observed in mice exposed to the Iowa Chemical Mixture. Evidence from the literature is discussed in order to infer which chemical or chemicals in the California Chemical Mixture might be responsible for the observed sister chromatid exchange response.

LC50; Species: Anas platyrhynchos (Mallard Duck) age 14 days; dietary >10000 ppm for 8 days

LC50; Species: Anas platyrhynchos (Mallard Duck) age 10 days; dietary >5620 ppm for 8 days /S-Metolachlor/

LD50; Species: Anas platyrhynchos (Mallard Duck) age 14 days; oral via capsule 4640 mg/kg (95% confidence interval: 3000-7200 mg/kg)

LD50; Species: Anas platyrhynchos (Mallard Duck) age 16 wk; oral via capsule >2510 mg/kg /S-Metolachlor/

For more Ecotoxicity Values (Complete) data for METOLACHLOR (58 total), please visit the HSDB record page.

TERRESTRIAL FATE: Based on a classification scheme(1), a range of Koc values from 22 to 2320(2-4) indicates that metolachlor is expected to have very high to slight mobility in soil(SRC). Volatilization was shown to be affected by residue cover, spatial concentration on the surface and timing of precipitation; cumulative volatilization loss of 22% and 6% applied using broadcast treatment and banded treatment, respectively, was noted during a 10 day field study(5). However, volatilization from moist soil surfaces is not expected to be an important fate process(SRC) given a Henry's Law constant of 9.0X10-9 atm-cu m/mole(6). Metolachlor is not expected to volatilize from dry soil surfaces(SRC) based upon a vapor pressure of 3.14X10-5 mm Hg(7). Some loss of metolachlor from soil surfaces will occur as a result of photolysis by sunlight(6). Metolachlor was not biodegraded in contaminated soil after 160 days of incubation(8), indicating that biodegradation is not an importanat environmental fate process in soil(SRC).

TERRESTRIAL FATE: Degradation half-lives of metolachlor simulated under varying laboratory conditions. Observed field degradation half-lives of metolachlor in loamy soil (42% sand, 24% clay, 34% silt, 1.7% organic matter) were 17.7, 28.8 and 17.2 days in 1993, 1994 and 1996, respectively(1). [Table#6197]

TERRESTRIAL FATE: Degradation half-lives of metolachlor were 14 and 7 days in Sungai Buluh (organic carbon 2%, clay 10%, silt 3.7%, sand 86.3%, pH 4.8) and Holyrood (organic carbon 1%, clay 21.1%, silt 4.1%, sand 74.8%, pH 4.6) series soils under simulated natural conditions(1). Degradation of metolachlor was studied in an aqueous/sediment environment for 112 days using Bojac sandy loam collected from the eastern shore of Virginia(2). The degradation rate constant and half-life of metolachlor in the sediment were 0.008/day and 34 days, respectively, the values in the water layer were 0.012/day and 8 days, respectively(2). Degradation rate constants and half-lives in soil without switchgrass were 0.52/day and 9.6 days, respectively, in soil with switchgrass values were 0.53/day and 6.0 days, respectively(2). [14C]Metolachlor was studied in a fresh water-sediment temperature-controlled greenhouse at 25 °C with a 14:10 hour light:dark photoperiod(3). The distribution of [14C]metolachlor was 23.7% in water, 6.6% in sediment and [14C]metolachlor extractable degradates, including carbinol and morpholinone, were 37.4% in water and 5.2% in sediment after 16 days of incubation(3). After 60 days of incubation the distribution of [14C]metolachlor was 0.7% in water, 0.6% in sediment and [14C]metolachlor extractable degradates were 60.6% in water and 9.2% in sediment(3). Degradation rate constants for metolachlor in three fields in eastern Colorado were 0.037 to 0.039/day with corresponding half-lives of 18.8 to 17.9 days, experiments were conducted from 2003 to 2005(4). The dissipation of metolachlor was detected following 3 applications to a clay loam soil at the Animal Research Center Farm, Ottawa between 1987 and 1990(5). Residue decline, leachability into the soil profile, movement into tile drainage water, and contamination of the groundwater of metolachlor were measured; and the amount of the herbicide applied to the soil surface was accounted for in the upper layer during the first week following treatment. The decline of metolachlor was followed in the upper 15 cm of the soil for 332, 364, and 370 days respectively in 1987, 1988 and 1989 and the half-lives of 80, 99, and 142 days were calculated. Metolachlor was present in groundwaters 1.2 to 4.6 m deep between the fall of 1988 to the summer of 1989. It was estimated that by the end of the season between 0.06 and 0.19% of the metolachlor moved into the shallow groundwater between the depths of 1.2 and 4.6 m(5).

AQUATIC FATE: Based on a classification scheme(1), a range of Koc values from 22 to 2320(2-4) indicate that metolachlor is expected to adsorb to suspended solids and sediment(SRC). Volatilization from water surfaces is not expected(5) based upon a Henry's Law constant of 9.0X10-9 atm-cu m/mole(6). When an aqueous solution of metolachlor was irradiated with natural sunlight, only 8% of the metolachlor photodecomposed in 30 days(6). However, the photolysis half-life of metolachlor in lake water under summer conditions was reported as 11 days(7). Humic substances retarded the photolysis of metolachlor in water(8). The estimated hydrolysis half-life of metolachlor in water is 210 days(9). According to a classification scheme(10), whole body BCFs of <1(11) and 99(6) suggest the potential for bioconcentration in aquatic organisms is low to moderate(SRC). The aquatic biodegradation half-lives for metolachlor under aerobic and anaerobic conditions are 47 and 78 days, respectively(12). The disappearance of metolachlor in groundwater free of aquifer materials (e.g., sand) was very slow and the half-life was in the range of 548-1074 days(13).

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), metolachlor, which has a vapor pressure of 3.14X10-5 mm Hg at 25 °C(2), will exist in both the vapor and particulate phases in the ambient atmosphere(SRC). Vapor-phase metolachlor 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 7 hrs(SRC), calculated from its rate constant of 7.02X10-11 cu cm/molecule-sec at 25 °C(3). Particulate-phase metolachlor may be removed from the air by wet and dry deposition(SRC). Metolachlor absorbs light in the environmental spectrum and has the potential for direct photolysis in the atmosphere(SRC). Photolysis half-lives ranging from 8-22 days have been reported in the atmosphere(4).

The Food and Drug Administration's regulatory monitoring program for the period 1982-1986 detected metolachlor in raw agricultural commodities collected in the United States(1). However, neither the commodities that contained metolachlor nor the levels in these commodities were reported(1). Metolachlor was not found (detection limit 0.01 mg/kg) in samples of composite vegetables representing nine vegetable commodities collected from Ontario, Canada between 1980-1985(2). In 2007, 8172 samples of fresh produce and 1562 samples of processed produce were analyzed: 528 banana, 504 blueberry, 20 frozen blueberry, 419 cherry, 739 green bean, 359 kale green, 563 nectarine, 555 peach, 800 frozen potato and 741 tomato samples did not contain metolachlor, however two of 731 broccoli, 12 of 739 celery and one of 335 collard greens tested positive for metolachlor(3).

The substance can be absorbed into the body by inhalation of its aerosol.

Inhalation (L914) ; oral (L914) ; dermal (L914) ; eye contact (L914).

Metolachlor acts by inhibition of elongases and of the geranylgeranyl pyrophosphate (GGPP) cyclases, which are part of the gibberellin pathway. It also binds to nAChRs in nervous systems and causes endocrine disruption in humans by binding to and inhibiting the estrogen receptor. (T10, L913, A590)

/BIRDS and MAMMALS/ ...Studies indicate metolachlor has chronic reproductive effects on birds and mammals at the highest tested dose. These effects, noted for both groups of organisms at approximately 1000 mg/kg diet, include a reduction in the number of eggs (birds) and reduced weight of pups (rats). No treatment-related mortality or other effects were noted in the studies.

/AQUATIC SPECIES/ /Researchers/ examined the toxicity mitigation efficiency of a hydrologically modified backwater wetland amended with a pesticide mixture of atrazine, metolachlor, and fipronil, using 96 hr survival bioassays with Hyalella azteca /scud/. Significant H. azteca 96 hr mortality occurred within the first 2 hr of amendment at the upstream amendment site but not at any time at the downstream site. H. azteca survival varied spatially and temporally in conjunction with measured pesticide mixture concentrations. Hyalella azteca 96 hr survival pesticide mixture effects concentrations ranges were 10.214-11.997, 5.822-6.658, 0.650-0.817, and 0.030-0.048 ug/L for atrazine, metolachlor, fipronil, and fipronil-sulfone, respectively.

/AQUATIC SPECIES/ The toxicities of two herbicides (alachlor and metolachlor) and an organophosphate insecticide (chlorpyrifos) were evaluated individually and with either herbicide in binary mixture with chlorpyrifos in fourth-instar larvae of the aquatic midge (Chironomus tentans). Alachlor alone up to 1,000 ug/L did not exhibit significant toxicity, whereas metolachlor at 1,000 ug/L affected 58% of midges in 72 hr bioassays. However, alachlor at 1,000 ug/L and metolachlor at 10, 100, and 1,000 ug/L enhanced the toxicity of chlorpyrifos to the midges. Furthermore, alachlor and metolachlor at 1,000 ug/L reduced acetylcholinesterase (AChE) activity by 34.3% and 27.6%, respectively, in the treated midges. Although alachlor at 1,000 ug/L did not significantly affect protein production in the treated midges, it reduced glutathione S-transferases (GST) total activities by 1.9 to 2.1 fold. In contrast, metolachlor at 1,000 ug/L reduced protein production by 3.2 fold, which was associated with a 2.8 fold reduction of cytochrome P450 O-deethylation total activity and 1.4 to 1.7 fold reductions of GST total activities in the treated midges. Such reduced total activities of the major detoxification enzymes in herbicide-treated midges might impede the metabolic detoxification of chlorpyrifos and, therefore, increase the susceptibility of the midges to chlorpyrifos.

/AQUATIC SPECIES/ The toxicity of the chiral herbicides rac-metolachlor and S-metolachlor to Chlorella pyrenoidosa /green algae/ was determined and compared in this study, based on four different test endpoints: the growth inhibition rate, the chlorophyll a and chlorophyll b concentration, the catalase activity, and the ultrastructural morphology of cells. The 24, 48, 72, and 96 hr EC50 values of rac-metolachlor were 0.196, 0.241, 0.177 and 0.152 mg/L, respectively; these values were higher than those of S-metolachlor, which were 0.116, 0.106, 0.081 and 0.068 mg/L, respectively. This indicates that S-metolachlor was more toxic to C. pyrenoidosa than rac-metolachlor. The Chla and Chlb concentration of C. pyrenoidosa treated by rac-metolachlor was higher than that treated by S-metolachlor. In general, the catalase activity of C. pyrenoidosa treated by S-metolachlor was higher than that exposed to rac-metolachlor, and catalase activity was inhibited at high concentrations of both herbicides. The ultrastructural morphology of cells grown in the two herbicides was observed by transmission electron microscopy. The cell wall separated from the cell membrane, accumulated starch granules were observed in the chloroplast, and some lipid droplets and unknown electron-opaque deposits were also observed in the cytoplasm.

For more Ecotoxicity Excerpts (Complete) data for METOLACHLOR (16 total), please visit the HSDB record page.

Tolerances are established for the combined residues (free and bound) of the herbicide metolachlor, 2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide, and its metabolites, determined as the derivatives, 2-[(2-ethyl-6-methylphenyl)amino]-1-propanol and 4-(2-ethyl-6-methylphenyl)-2-hydroxy-5-methyl-3-morpholinone, each expressed as the parent compound in the following raw agricultural commodities: [Table#6198]

Tolerances are established for residues of S-metolachlor, including its metabolites and degradates, in or on the commodity(s), as defined. Compliance with the tolerance levels specified in the following table below is to be determined by measuring only the sum of free and bound S-metolachlor, S-2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide, its R-enantiomer, and its metabolites, determined as the derivatives, 2-(2-ethyl-6-methylphenyl)amino-1-propanol and 4-(2-ethyl-6-methylphenyl)-2-hydroxy-5-methyl-3-morpholinone, calculated as the stoichiometric equivalent of S-metolachlor, in or on the commodity. /S-Metolachlor/ [Table#6199]

Tolerances with regional registration as defined in 180.1(l) are established for the combined residues (free and bound) of the herbicide metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide] and its metabolites, determined as the derivatives, 2-[2-ethyl-6-methylphenyl)amino]-1-propanol and 4-(2-ethyl-6-methylphenyl)-2-hydroxy-5-methyl-3-morpholinone, each expressed as the parent compound, in or on the following raw agricultural commodities: [Table#6200]

Tolerances with regional registration are established for residues of S-metolachlor, including its metabolites and degradates, in or on the commodities identified in the following table below. Compliance with the tolerance levels specified in the following table below is to be determined by measuring only the sum of free and bound S-metolachlor, S-2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide, its R-enantiomer, and its metabolites, determined as the derivatives, 2-(2-ethyl-6-methylphenyl)amino-1-propanol and 4-(2-ethyl-6-methylphenyl)-2-hydroxy-5-methyl-3-morpholinone, calculated as the stoichiometric equivalent of S-metolachlor, in or on the commodity. /S-Metolachlor/ [Table#6201]

For more FIFRA Requirements (Complete) data for METOLACHLOR (8 total), please visit the HSDB record page.

(FL) FLORIDA 110 ug/L

(MA) MASSACHUSETTS 100 ug/l

(ME) MAINE 100 ug/l

(MN) MINNESOTA 300 ug/L

For more State Drinking Water Guidelines (Complete) data for METOLACHLOR (7 total), please visit the HSDB record page.

METABOLISM IN PLANTS AFTER PREEMERGENCE APPLICATION OF METOLACHLOR APPEARS TO PROCEED BY NATURAL PRODUCT CONJUGATION OF THE ACETYL-CHLORO GROUP WITH THIS BOND LINKAGE PREDOMINANT OVER OXO. FURTHER REACTION OCCURS AT THE ETHER GROUP WITH HYDROLYSIS FOLLOWED BY SUGAR CONJUGATION. FINAL METABOLITES ARE RESULTS OF DISCONJUGATION, AND ARE POLAR, AQUEOUS SOLUBLE, NONVOLATILE AS WELL AS SENSITIVE TO DEGRADATION. HYDROLYSIS PROCEDURES CONVERT THE OXO-METABOLITES TO THE DEACETYLATED DERIVATIVE AND THE THIO-METABOLITES TO A MORPHOLINE DERIVATIVE.

STUDIES WITH THE ANTOR ANALOG METOLACHLOR (DUAL) WERE ALSO CONDUCTED WITH THE FUNGUS CHAETOMIUM GLOBOSUM. COMPOUNDS PRODUCED BY THIS ORGANISM WHEN INCUBATED WITH METOLACHLOR ARE: 2-CHLORO-N-(2-ETHYL-6- METHYLPHENYL)-N-(2-HYDROXY-1-METHYLETHYL)ACETAMIDE; 2-CHLORO-N-(2-ETHYL- 6-METHYLPHENYL)ACETAMIDE; N-(2-METHOXY-1-METHYLETHYL)-2-METHYL-6-VINYLANILINE; N-(2-METHOXY-1-METHYLETHYL)-2,3-DIHYDRO-7-METHYLINDOLE; 8-ETHYL-3-HYDROXY- N-(2-METHOXY-1-METHYLETHYL)-2-OXO-1,2,3,4-TETRAHYDROQUINOLINE; 8-ETHYL-3- HYDROXY-N-ISOPROPYL-2-OXO-1,2,3,4-TETRAHYDROQUINOLINE; 2-HYDROXY-N-(2- METHOXY-1-METHYLETHYL)-N-(2-METHYL-6-VINYLPHENYL)ACETAMIDE; N-(2-METHOXY- 1-METHYLETHYL)-8-METHYL-2-OXO-1,2,3,4-TETRAHYDROQUINOLINE.

IN FUNGI, ALPHA-CHLORINE ATOMS OF THESE PESTICIDES /INCLUDING METOLACHLOR/ ARE NOT DISPLACED BY SULFHYDRYL GROUPS BUT BY HYDROXYL GROUPS ALTHOUGH THE CHLORINE ATOM OF PROPACHLOR IS DISPLACED BY A SULFHYDRYL GROUP IN THE FIRST DEGRADATION STEP IN PLANTS. DEALKYLATION, DEACYLATION, AND RING FORMATION TO FORM INDOLINES AND QUINOLINES OCCUR IN FUNGI.

Studies conducted to identify urinary and fecal metabolites in the rat indicated that metolachlor is metabolized via dechlorination, o-methylation, N-dealkylation and side-chain oxidation. Urinary metabolites included 2-ethyl-6-methylhydroxyacetanilide and N-(2-ethyl-6-methyl- phenyl)-N-(hydroxyacetyl)-DL-alanine). Fecal metabolites included 2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-hydroxy-l-methylethyl) and N-(2-ethyl-6-methylphenyl)-N-(hydroxyacetyl)-DL-alamine).

For more Metabolism/Metabolites (Complete) data for METOLACHLOR (10 total), please visit the HSDB record page.

Metolachlor is metabolized via dechlorination, o-methylation, N-dealkylation and side-chain oxidation. Glutathione transferases mediathe the conjugation of metolachlor with with glutathione. Urinary metabolites included 2-ethyl-6-methylhydroxyacetanilide and N-(2-ethyl-6-methyl- phenyl)-N-(hydroxyacetyl)-DL-alanine). Fecal metabolites included 2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-hydroxy-l-methylethyl) and N-(2-ethyl-6-methylphenyl)-N-(hydroxyacetyl)-DL-alamine). Metolachlor is also excreted in urine. (A571, A270)

S-metolachlor is extensively absorbed and metabolized following oral administration. Elimination is via the urine and feces. Tissue residues were highest in whole blood. /s-metolachlor/

Selective herbicide, absorbed predominantly by the hypocotyls and shoots.

Rats were administered a single oral dose (28.6 or 52.4 mg/kg) of metolachlor (purity not specified, but (14)C labeled and unlabeled metolachlor were synthesized for these experiments). The chemical was readily absorbed, since 70 to 90% of the metolachlor was excreted as metabolites within 48 hr.

Data from rats given radioactive metolachlor (approximately 3.2 to 3.5 mg/kg) orally demonstrated that the chemical is rapidly metabolized. Residues in meat tissue and blood were very low and only blood contained residue levels in excess of 0.1 ppm.

For more Absorption, Distribution and Excretion (Complete) data for METOLACHLOR (6 total), please visit the HSDB record page.

Used to control weeds in crops of corn, soybeans, peanuts, sorghum, potatoes, peas, cotton, safflower, stone fruits, nut trees, and ornamentals; also used on roadways; [EXTOXNET] Used in corn, peanuts, and soybeans; [Krieger, p. 1762]

Farming (Pesticides) [Category: Industry]

For metolachlor (USEPA/OPP Pesticide Code: 108801) 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./

Herbicide

Preemergence and preplant incorporated weed control

Control of annual grasses and some broad-leaved weeds ... Often used in combination with broad-leaved herbicides, to extend the spectrum of activity.

(A) A mixture of 540 g (4.0 mols) of 2-ethyl-6-methylaniline and 306 g (2.0 moles) of 2-bromo-1-methoxypropane is heated for 40 hours at reduced pressure (10 mmHg) to 120 °C with stirring. After it has cooled, the light red, viscous solution is diluted with 200 mL of water and made alkaline with 210 mL of concentrated sodium hydroxide solution. The precipitated product is taken up in ether, and the ethereal solution is washed neutral with water, dried, and evaporated. Distillation of the residue yields pure-2-ethyl-6-methyl-N-[1'-methoxy-prop-2'-yl]-aniline which boils at 64 deg to 66 °C/0.07 Torr. (B) A solution of 9.7 g (0.047 mol) of the intermediate described under (A) and 5.05 g (0.05 mol) of triethylamine in 30 mL of benzene is treated dropwise with a solution of 5.65 g (0.05 mol) of chloroacetyl chloride in 10 mL of absolute benzene, and the mixture is further stirred for 2 hours at room temperature. The reaction mixture is diluted with ether, the solution repeatedly washed with water, and dried. The solvent mixture is evaporated off in vacuo to give pure-2-ethyl-6-methyl-N-[1'-methoxy-prop-2'-yl]-chloroacetanilide.

Preparation: C. Vogel, R. Aebi, DE 2328340; eidem, US 3937730 (1973, 1976 both to Ciba-Geigy).

USEPA/OPP Pesticide Code 108801; Trade Names: Milocep; Dual; CGA-24705; Bicep; codal; Cotoran multi; Primagram; Primextra; Pennant; and Ontrack 8E.

Premix Partners: Atrazine; Chloridazon; Metribuzin.

Formulation types: Emulsifiable concentrate, granule, smoke pellet, suspension concentrate

Technical Metolachlor II (Agan Chem MFG, LTD): Metolachlor 96.8%.

For more Formulations/Preparations (Complete) data for METOLACHLOR (27 total), please visit the HSDB record page.

Herbicides

Pesticides -> Herbicides -> Amide herbicides -> Anilide herbicides -> Chloroacetanilide herbicides

HERBICIDES