Metobromuron

Herbicides

Active substance -> EU Pesticides database: Approved

Pesticides -> Herbicides, Urea Derivative

Environmental transformation -> Pesticides (parent, predecessor)

Herbicides

Pesticide (Metobromuron) -> USDA PDB

CRYSTALS FROM CYCLOHEXANE

WHITE CRYSTALS

IN WATER: 320 PPM AT 20 °C; SOL IN METHANOL, ETHANOL, ACETONE, CHLOROFORM

At 20 °C, in water 0.88 mg/100 g; in acetone more than 100 g/100 g; in ethanol 18.2 g/100 g; in chloroform 62.5 g/100 g

0.000003 [mmHg]

3X10-6 MM HG @ 20 °C

147.7 Ų [M-H]- [CCS Type: DT; Buffer gas: N2; Ionization: ESI-; Dataset: TOXCAST; Source Identifier: DTXSID6042157]

145.41 Ų [M+H]+ [CCS Type: TW]

This chemical does not meet GHS hazard criteria for 5.1% (3 of 59) of reports.

Warning

H302 (93.2%): Harmful if swallowed [Warning Acute toxicity, oral]

P203, P260, P261, P264, P270, P271, P273, P280, P301+P317, P304+P340, P317, P318, P319, P330, P391, P405, and P501 (click each P-code to see the statement)

Aggregated GHS information provided per 59 reports by companies from 5 notifications to the ECHA C&L Inventory. Each notification may be associated with multiple companies.

Regulation (EC) No 396/2005 (amended)

2011/253/EU, Reg. (EC) No 2076/2002, Reg. (EU) 2018/155, Reg. (EU) 2024/2781, Reg. (EU) No 890/2014

Urea-derived herbicides have low toxicity in animal feeding studies; May induce methemoglobinemia; [HSDB] Systemic toxicity unlikely unless large amounts ingested; [EPA Pesticides, p. 122] An eye irritant; Harmful by ingestion and inhalation; [Sigma-Aldrich MSDS]

SRP: At the time of review, 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.

Hydrolysis is not recomended as a disposal procedure because of the generation of the toxic products, 3,4-dichloroaniline and dimethylamine.

Metobromuron should be incinerated in a unit operating at 850 °C with off gas scrubbing equipment. Recommendable method: Incineration.

LC50 TROUT 71-85 PPM/96 HR EXPOSURE /CONDITIONS OF BIOASSAY NOT SPECIFIED/

LC50 GOLDFISH 71-85 PPM/96 HR EXPOSURE /CONDITIONS OF BIOASSAY NOT SPECIFIED/

LC50 BLUEGILL 71-85 PPM/96 HR EXPOSURE /CONDITIONS OF BIOASSAY NOT SPECIFIED/

LD50 BEE MORE THAN 160 UG/BEE /CONDITIONS OF BIOASSAY NOT SPECIFIED/

... TERRESTRIAL FATE: METOBROMURON DISAPPEARED AT A FASTER RATE THAN FLUOMETURON /FROM SOIL/.

TERRESTRIAL FATE: Based on a recommended classification scheme(1), an estimated Koc value of 470(SRC), determined from an experimental log Kow(2,SRC) and a recommended regression-derived equation(3), indicates that metobromuron should have moderate mobility in soil(SRC). Volatilization of metobromuron should not be important from moist soil surfaces(SRC) given an estimated Henry's Law constant of 3.1X10-9 atm-cu m/mole(SRC), calculated from experimental values for vapor pressure(4) and water solubility(5), or from dry soil surfaces(SRC) based on an experimental vapor pressure of 3X10-6 mm Hg(4). Metobromuron may photolyze on soil surfaces(SRC) according to two studies(6,7). A variety of pure culture biodegradation studies, including biodegradation in plants, algae, and fungi(8-11), suggest that metobromuron may biodegrade in water(SRC).

AQUATIC FATE: Based on a recommended classification scheme(1), an estimated Koc value of 470(SRC), determined from an experimental log Kow(2) and a recommended regression-derived equation(1), indicates that metobromuron may adsorb to suspended solids and sediment(SRC) in the water. Metobromuron will be essentially non-volatile from water surfaces based on an estimated Henry's Law constant of 3.1X10-9 atm-cu m/mole(SRC), calculated from experimental values for vapor pressure(3) and water solubility(4). An estimated BCF value of 38(1,SRC), from an experimental log Kow(2), suggests that metobromuron may bioconcentrate in aquatic organisms(SRC), according to a recommended classification scheme(5). A variety of pure culture biodegradation studies, including biodegradation in plants, algae, and fungi(6-9), suggest that metobromuron may biodegrade in water(SRC).

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), metobromuron, which has an experimental vapor pressure of 3X10-6 mm Hg at 25 °C(2), will exist as a vapor in the ambient atmosphere. Vapor-phase metobromuron 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 about 28 hours(3,SRC). Particulate-phase metobromuron may be physically removed from the air by wet and dry deposition(SRC).

Metobromuron /is/ ... moderately mobile in the soil ... Movement of the cmpd also decr as organic matter content of the soil incr, and in turn the herbicidal activity of the phenylureas decr as the cmpd are bound to the soil organic matter.

Soil adsorption coefficient: 60 (experimental); 180 (calculated). /From table/

The Koc of metobromuron is estimated as approximately 470(SRC), using an experimental log Kow of 2.38(1) and a regression-derived equation(2,SRC). The Koc for metobromuron has also been experimentally determined to be 104.7(3). For soil with organic carbon levels of 0.58-2.3%, metobromuron had an average experimental Koc value of 60(4). The average Koc value from eight soils of Czechoslovakia with organic matter contents ranging from 0.1-4.6% was 490(5). According to a recommended classification scheme(6), this estimated Koc value suggests that metobromuron should have medium to high mobility in soil(SRC).

... The two fungi, Talaromyces wortmanii and Fusarium oxysporum metabolized (14)C-labeled metobromuron, whereas a Bacillus sp and the alga Chlorella vulgaris were unable to degrade the same herbicide.

Talaromyces wortmanii and Fusarium oxyporum degrade metobromuron by N-demethoxylation.

/Metobromuron was incubated/ with soil-enrichment solutions and pure cultures of active microbial isolates. ... It was shown that in the presence of the fungus, Fusarium oxysporum, halogen ions were released into the culture medium from ... metobromuron.

The degradation of metobromuron by a linuron-inducible enzyme produced by Bascillus sphaericus had a specific activity of the cell-free extract of 0.18X10-3 units/mg of protein and produced 4-bromoaniline(1). The fungus Rhizoctonia solani was able to transform metobromuron by 70% after 6 days(2). In plants, the methyl and methoxy groups are split off and the urea moiety is further degrade to 4-bromoaniline(3). Presumably there is simultaneous ring hydroxylation and fission(3). Two fungi, Talaromyces wortmanii and Fusarium oxysporum metabolized 14C-labeled metobromuron, whereas neither Bascillus sphaericus nor the alga Chlorella vulgaris were able to degrade metobromuron(4).

Predicted Bioconcentration Factor: 23, based on calculated water solubility; 3, based on calculated soil adsorption coefficient.

An estimated BCF value of 38 was calculated for metobromuron(SRC), using an experimental log Kow of 2.38(1) and a recommended regression-derived equation(2). According to a recommended classification scheme(3), this BCF value suggests that bioconcentration in aquatic organisms may be moderate, not high(SRC).

The Henry's Law constant for metobromuron is estimated as 3.1X10-9 atm-cu m/mole(SRC) from its experimental values for vapor pressure, 3X10-6 mm Hg(1), and water solubility, 330 mg/l(2). This value indicates that metobromuron will be essentially nonvolatile from water surfaces(3,SRC). Metobromuron's vapor pressure(1) and Henry's Law constant(1,2,SRC) indicate that volatilization from dry and moist soil surfaces should not occur(SRC).

In 2-yr feeding trials rats receiving 250 mg/kg diet and dogs 100 mg/kg diet were unaffected. It is of low toxicity to wildlife.

Fatally poisoned animals exhibited adipsia, dyspnea, hypothermia, and anuria. Death occurred within two days and was due to cardiac or respiratory failure. In survivors, recovery was accompanied by diuresis, alkalinuria, and /less frequently/ hematuria, glycosuria, or proteinuria. Clinical signs of poisoning disappeared in 3 to 4 days. Autopsies of fatally poisoned rats revealed gastroenteritis, fatty necrosis of the liver, renal, and splenic pallor, and degenerative changes in kidneys, muscle, salivary glands, and testes. Capillary venous congestion in brain, heart, and lung accompanied by signs of a stress reaction in adrenal, spleen, and thymus. /Monuron/

The effect of substituted urea herbicides on rat hepatic microsomal epoxide-hydroxylase activity was studied in-vitro. Male Wistar-rats were given 16.7% of the median lethal dose (LD50) of diuron, linuron, chlorbromuron, chlortoluron, metoxuron, monolinuron, metobromuron or isoproturon on 3 consecutive days by oral gavage. The animals were killed 24 hr after the last dose and the livers were removed. Epoxide-hydroxylase activity was determined by a HPLC assay using styrene-oxide as the substrate and styrene-glycol as the standard. Indices of induction were calculated. The experimental values of epoxide-hydrolase activity in nmoles/min/mg protein were: control, 7.2; diuron, 13.8; linuron, 12.1; chlorbromuron, 13.2; chlortoluron, 21.8; metoxuron, 16.1; monolinuron, 12.6; metobromuron, 10.6; and isoproturon, 29.5. The indices of induction were: diuron, 0.37; linuron, 0.25; chlorbromuron, 0.29; chlortoluron, 0.26; metoxuron, 0.53; monolinuron, 0.43; metobromuron, 0.37; and isoproturon, 0.82. The authors note that the herbicides that have two halogen substituents on the phenyl moiety have higher molar induction that those which have only a single halogen substituent or none.

The effects of eight structurally related, substituted urea herbicides on the hepatic cytochrome-P-450 dependent monooxygenase enzyme were investigated in rats. Male Wistar-rats were given one sixth the median lethal dose of herbicides by gavage on 3 consecutive days. The doses admin were 57 mg/ml diuron, 67 mg/ml linuron, 83 mg/ml chlorbromuron, 166 mg/ml chlortoluron, 53 mg/ml metoxuron, 38 mg/ml monolinuron, 33 mg/ml metobromuron and 77 mg/ml isoproturon. Animals were sacrificed 24 hr after the last treatment with the herbicides. Cytochrome-P-450 and cytochrome-b-5 content of liver microsomes were determined by difference spectrophotometry. Chlortoluron was the only cmpd that increased the relative liver weight to body weight while monolinuron decreased the value. Diuron, linuron, and chlorbromuron increased cytochrome-P-450 content by approx 50 percent; the other herbicides caused smaller induction. Metoxuron was the only cmpd that had no effect on cytochrome-P-450 content. Cytochrome-b-5 content of microsomes was changed within a 20 percent range and only linuron enhanced it significantly. Diuron, linuron, chlorbromuron, and chlortoluron were the most effective inducers of benzo(a)pyrene monooxygenase, causing a 3.5 to 8 fold induction; monolinuron and metobromuron induced a 2 fold incr whereas metoxuron and isoproturon had no effect. Among aldrin-epoxidase activities the greatest induction was obtained with isoproturon. Linuron and chlortoluron were less effective, and no significant changes was obtained with the other five cmpds. Diuron, chlorbromuron, chlortoluron, and isoproturon enhanced uridine-diphosphate-glucuronyltransferase and glutathione-S-transferase activities. The authors conclude that the number of halogen substituents on the phenyl group of substituted urea cmpds exert a strong influence on the induction of monoxygenases.

Toxic doses /in rats/ caused ataxia, drowsiness, hyporeflexia, pallor, and tachypnea, progressing to dacryorrhea, aciduria, diarrhea, epistaxis, hyperreflexia, and irritability. /Monuron/

... METOBROMURON IS CONVERTED TO CORRESPONDING PHENOL BY PHOTOLYTIC REPLACEMENT OF BR ...

The rate constant for the vapor-phase reaction of metobromuron with photochemically produced hydroxyl radicals has been estimated as 1.38X10-11 cu cm/molecule-sec at 25 °C(SRC) using a structure estimation method(1,SRC). This corresponds to an atmospheric half-life of about 29 hours at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm(1,SRC). Metobromuron, in a 225 mg/l aqueous solution, was irradiated with sunlight for a 17-day period in late summer resulted in a mixture containing 80% unchanged metobromuron and 15% 3-(p-hydroxyphenyl)-1-methoxy-1-methylurea(2). The remaining material consisted of at least 3 compounds: 3-(p-bromophenyl)-1-methylurea, p-bromophenylurea, and an unidentified material or materials(2). After irradiating for 135 minutes with a 300-nm sunlight lamp in water, and two surfactants TMN-10 and X-100, at a concentration of 100 mg/l, metobromuron degraded 59, 53, and 60%(3).

METOBROMURON IS METABOLIZED IN PLANTS & ANIMALS BY N-DEMETHYLATION & N-DEMETHOXYLATION, RESPECTIVELY.

... RING-LABELED (14)C-METOBROMURON WAS SUPPLIED TO POTATOES AND CORN SEEDLINGS. ... FOLLOWING METABOLITES ... /WERE IDENTIFIED/: 3-(4-BROMOPHENYL)-1-METHOXYUREA, 3-(4-BROMOPHENYL)-1-METHYLUREA, AND 4-BROMOPHENYLUREA.

METOBROMURON YIELDS 3-(P-BROMOPHENYL)-1-METHYLUREA AND 3-(P-BROMOPHENYL)-1-METHOXYUREA IN TALAROMYCES. /FROM TABLE/

(14)C-Metobromuron was incubated with human embryonic lung (HEL) cells. More than 95% of the label was recovered as unchanged metobromuron. Of four metabolites, three were identified: 3-(4-bromophenyl)-1-methylurea; 4-bromophenylurea; and 3-(4-bromophenyl)-1-methylurea.

METOBROMURON IS ABSORBED BY ROOTS AND LEAVES ...

... Different urea herbicides exhibit different mobilities in plant systems. ... Uptake and translocation of chloroxuron, fluometuron, and metobromuron by bean plants when supplied to nutrient cultures in equal concn (essentially equimolar) and specific radioactivities were studied. Whereas the movement of chloroxuron to aerial parts was found to be restricted under the short-term conditions applied, both fluometuron and metobromuron were rapidly translocated into leaves. However, the two latter cmpd differed strikingly with regard to their distribution pattern within the leaves. In contrast to metobromuron, which was mainly confined to tracheal veins, fluometuron had almost completely moved out into the mesophyll tissues. Although no extensive comparisons of the movement of different urea structures are available at this time, it would appear that their apoplastic distribution in plants is regulated in part by the same physical-chemical phenomena which control the mobility and availability of the cmpd in soil.

Used as pre-emergence herbicide to control annual broad-leaved weeds and grasses in beans, soybeans, tomatoes, tobacco, potatoes, flax, and sunflowers; Not sold in the US; [HSDB] Used in the EU as herbicide on potatoes; [ExPub: EC: EFSA]

Farming (Pesticides) [Category: Industry]

Used on beans, soybeans, tomatoes, tobacco, potatoes, flax, and sunflowers.

/IT IS A/ SELECTIVE PRE-EMERGENT ANNUAL BROADLEAFED WEED AND GRASS CONTROL IN POTATOES, WHITE (FIELD) AND SNAP (BUSH) BEANS, AT 1.5-2.5 KG AI/HECTARE ... /IT IS/ SOMEWHAT LESS EFFECTIVE AGAINST GRASSES, PARTICULARLY AT LOW RATES.

... RECOMMENDED FOR PRE-EMERGENCE USE ON POTATOES, BEANS, GROUNDNUTS AT RATES OF 1.5-2.0 KG AI/HECTARE, ON TOBACCO PRIOR TO TRANSPLANTING AT 1.5-2.5 KG AI/HECTARE.

As a herbicide.

PREPARED BY BROMINATION OF N-PHENYL-N'-METHOXY-N'-METHYLUREA: H MARTIN ET AL, SWISS PATENT 405,821 CORRESP TO US PATENT 3,288,851 (BOTH 1966 TO CIBA).

BY BROMINATION OF 1-METHOXY-1-METHYL-3-PHENYLUREA OR BY REACTION OF 4-BROMOPHENYL ISOCYANATE WITH O,N-DIMETHYLHYDROXYLAMINE. ... BRITISH PATENT 965,313; US PATENT 3,223,721.

Reaction of p-bromoaniline with phosgene and N,O-dimethylhydroxylamine (phosgenation/isocyanate addition).

50% wettable powder (BASF, Ciba-Geigy). In combination with metolachlor (Galex and Tobacron) or with terbutryn (Ingrater) Ciba-Geigy, 4 lb/gal (400 g/l) flowable (BASF)

Combinations: Igrater 50 WP (metobromuron 25% and terbutryn 25%); Galex 500 EC (metobromuron + metolachlor 1:1 or 2:3)

C 3126

Ciba-3126

For more Formulations/Preparations (Complete) data for METOBROMURON (6 total), please visit the HSDB record page.

Environmental transformation -> Pesticides (parent, predecessor)

Herbicides

Metobromuron is the bromophenyl analog of monuron.

Not marketed in USA.

... /IT/ BECOMES NON-PHYTOTOXIC IN 3 MO AT RECOMMENDED DOSAGES.

Substituted ureas may be hydrolyzed, whereby the end products are carbon dioxide and the corresponding amines. Hydrolysis proceeds under acid as well as alkaline conditions. This reaction is used for the quantitative analysis of active ingredients and/or residues of urea herbicide preparations by determining either the aromatic or the aliphatic amine moiety.