4-(4-Chloro-2-methylphenoxy)butanoic acid

228.67

228.67

202-365-3

OA1Z4N1842

102796

DTXSID4024193

WHITE SOLID|Colorless crystals; (tech., beige to brown flakes)

2918990023

46.5

2.79 (unstated pH)

clear colorless to slightly brown liquid

1.23g/cm3

100-101 °C

>280 °C

191.5ºC

1.536

In acetone 313, dichloromethane 169, ethanol 150, hexane 0.26, toluene 8 (all in g/L, room temperature)

0-6°C

4.3X10-7 mm Hg at 20 deg C

Oral-rat LD50: 680 mg/kg; Oral-Mouse LD50: 800 mg/kg

Thermal decomposition of toxic chloride gas

Acid

Henry's Law constant = 2.74X10-9 atm-cu m/mole at 25 °C (est)

pKa = 4.84

Form water-sol alkali metal and amine salts, though precipitation occurs with hard water|Non-corrosive to metals /MCPB salts/|Hydroxyl radical reaction rate constant = 2.02X10-11 cu cm/molec-sec at 25 °C (est)

Noncorrosive

UN30779/PG3

3

50/53

60-61

ES8575000

N

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

P273-P501

H410

Do not discharge effluent containing this product into lakes, streams, pond, estuaries, oceans or waters unless in accordance with the requirements of a National Pollutant 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. ... Do not contaminate water, food or feed by storage, disposal, or cleaning of equipment. Open burning and dumping is prohibited. Do not re-use empty container. Wastes resulting from use of this product may be disposed of on site or at an appropriate waste disposal facility. ... Completely empty drum and triple rinse. Offer for recycling or reconditioning or dispose in a sanitary landfill or by other State and local procedures. /Technical MCPB/|Pesticide Disposal: Do not contaminate water, food or feed by storage or disposal. Wastes resulting from the use of this product may be disposed of on site or at an approved waste disposal facility. Container Disposal: Triple rinse (or equivalent). Then offer for recycling or reconditioning, or puncture and dispose of in a sanitary landfill, or incineration, or, if allowed by state and local authorities, by burning. If burned, stay out of smoke. /Sodium MCPB/|SRP: The most favorable course of action is to use an alternative chemical product with less inherent propensity for occupational exposure or environmental contamination. Recycle any unused portion of the material for its approved use or return it to the manufacturer or supplier. Ultimate disposal of the chemical must consider: the material's impact on air quality; potential migration in soil or water; effects on animal, aquatic, and plant life; and conformance with environmental and public health regulations.

USEPA/Office of Pesticide Programs; Reregistration Eligibility Decision Document - MCPB and Salts EPA 738-R-06-016 (March 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 February 27, 2007: http://www.epa.gov/pesticides/reregistration/status.htm]

|Warning|H400: Very toxic to aquatic life [Warning Hazardous to the aquatic environment, acute hazard]|P273, P391, and P501|H302 (19.7%): Harmful if swallowed [Warning Acute toxicity, oral]|P264, P270, P273, P301+P312, P330, P391, and P501|Aggregated GHS information provided by 198 companies from 4 notifications to the ECHA C&L Inventory. Each notification may be associated with multiple companies.|H410: Very toxic to aquatic life with long lasting effects [Warning Hazardous to the aquatic environment, long-term hazard]|H302: Harmful if swallowed [Warning Acute toxicity, oral]|P264, P270, P301+P312, P330, and P501

Wear protective eyewear (goggles, face shield, or safety glasses). Wear long-sleeved shirt and long pants, socks, shoes, and chemical resistant gloves (such as Natural Rubber)... When handlers use closed systems, enclosed cabs, or aircraft in a manner that meets the requirements listed in the Worker Protection Standard (WPS) for agricultural pesticides (40 CFR 170.240 (d) (4-6)), the handler PPE requirements may be reduced or modified as specified in the WPS. /Sodium MCPB/|Agricultural Use Requirements. Use this product only in accordance with its labeling and with the Worker Protection Standard (WPS), 40 CFR part 170. ... Do not enter or allow worker entry into treated areas during the restricted-entry interval (REI) of 12 hours. ... PPE required for early entry to treated areas that is permitted under the WPS and that involves contact with anything that has been treated, such as plants, soil, or water, is: coveralls, waterproof gloves, and shoes plus socks./Sodium MCPB/

Nonflammable

If swallowed call a poison control center or doctor immediately for treatment advice. Have person sip a glass of water if able to swallow. Do not induce vomiting unless told to do so by a poison control center or doctor. Do not give anything by mouth to an unconscious person. If inhaled move person to fresh air. If person is not breathing, call 911 or an ambulance, then give artificial respiration ... if possible. Call a poison control center or doctor for further treatment advice. /Technical MCPB/|Wash thoroughly with soap and water after handling and before eating, drinking, chewing gom, or using tobacco. Remove and wash contaminated clothing before reuse. /Sodium MCPB/|Do not contaminate water, food, or feed by storage or disposal of this chemical.|Cleaning glassware and spray equipment: Thoroughly flush with detergents, dilute alkali, and water.|For more Preventive Measures (Complete) data for 2-METHYL-4-CHLOROPHENOXYBUTYRIC ACID (7 total), please visit the HSDB record page.

Causes pain and irritation on eyes and mucous membranes.

SEDIMENT: 2-Methyl-4-chlorophenoxybutyric acid was detected in 72% (max concn 24.2 ng/g), 75% (max concn 36.6 ng/g), 14% (max concn 40.3 ng/g), and 21% (max concn 100.3 ng/g) of samples from sediment cores obtained from four different salt marshes on the Essex coast of the UK(1).

moderately toxic

LD50 Rat acute dermal > 2000 mg/kg|LD50 Rabbit acute dermal > 10000 mg/kg|LD50 Rat acute oral = 4300 mg/kg|LD50 Rat acute oral = 1570 mg/kg|For more Non-Human Toxicity Values (Complete) data for 2-METHYL-4-CHLOROPHENOXYBUTYRIC ACID (6 total), please visit the HSDB record page.

/AQUATIC SPECIES/ In a 96-hour flow-through test, MCPB sodium was determined to be moderately toxic to rainbow trout with an LC50 of 4.3 mg ai/L. The NOEC was determined to be 1.0 mg ai/L. ... Study design: Six concentrations of chemical and dilution water control were used, each with two replicates of ten fish. Observations for mortality and sublethal effects were made daily throughout the exposure period. Reported results: The mean measured concentrations of MCPB NA were: 0(control), 8.0, 4.9, 2.8, 1.8, 1.0, and 0.60 mg ai/L. Sublethal effects (eg. Loss of equilibrium and darkening) were observed in surviving fish at the 4.9, 2.8, and 1.8 mg ai/L; there were no other abnormal effects at any other test levels. There was 100% mortality at the 8.0 mg ai/L level within 48 hours, 70% mortality at 4.9 mg ai/L level by 96 hours, and 5% at 2.8 mg ai/L at 96 hours. /Sodium MCPB/|/AQUATIC SPECIES/In a 96-hour flow-through test, MCPB sodium was determined to be slightly toxic to bluegill sunfish with an LC50 of 14 mg ai/L. The NOEC was determined to be 8.9 mg ai/L. ... Study design: Six concentrations of chemical and dilution water control were used, each with two replicates of 10 fish. Observations for mortality and sublethal effects were made daily throughout the exposure period. Reported results: The mean measured concentrations of MCPB NA were: 0(control), 29, 16, 8.9, 56.4, 3.5 and 2 mg ai/L. Sublethal effects (eg. Loss of equilibrium and darkening) were observed in surviving fish at the 16 mg ai/L level; There were no other sublethal abnormal effects at any other test levels. There was 100% mortality at the 25 mg ai/L within 72 hours, and 75% mortality at the 16 mg ai /L level by 96 hours. There was a single mortality at the 3.5 mg ai/L level, but this was not considered treatment related as there were no mortalities at the next highest level (8.9 mg ai/L). /Sodium MCPB/|/AQUATIC SPECIES/ Aquatic Plant Algae: Blue-green algae...In a Tier I toxicity test with blue-green algae, the EC50 for cell density was >2.1 mg ai/L. Tier II testing was not required for this species because the NOEC exceeded the maximum label rate of 1.5 lb ai/acre...Green algae...In a Tier I toxicity test with green algae, the 120-hour EC50 for cell density was 0.42 mg ai/L. ...Marine diatom... In a Tier I and II toxicity test with the marine diatom, the 120-hour EC50 for cell density was 1.5 mg ai/L... Diatom... In a Tier I and II toxicity test with the diatom, the 120-hour EC50 for cell density was 0.71 mg ai/L with a 95% confidence limit of (0.11 - 4.6), The NOEC was .048mg ai/L.|/AQUATIC SPECIES/In a 48-hour flow-through test, MCPB sodium was determined to be slightly toxic to daphnids with an EC50 of 55 mg ai/L (95% confidence interval of 49 - 63 mg ai/L). The NOEC was determined to be 20 mg ai/L. ... Study design: Five concentrations of chemical and dilution water control were used, each with two replicates of 20 daphnids. Observations for mortality and sublethal effects were made daily throughout the exposure period. Reported results: The mean measured concentrations of MCPB NA were: 0 (control), 87, 51, 33, 20, and 12 mg ai/L. Sublethal effects (e.g. lethargy an carapace) were observed in all surviving daphnids at 87 and 51 mg ai/L, and in 15% of the daphnids at 33 mg ai/L. There was 95% mortality at the 87 mg ai/L and 45% mortality at 51 mg ai/L by the end of the test period.|For more Ecotoxicity Excerpts (Complete) data for 2-METHYL-4-CHLOROPHENOXYBUTYRIC ACID (7 total), please visit the HSDB record page.

2-Methyl-4-chlorophenoxybutyric acid's production may result in its release to the environment through various waste streams; its use as a herbicide(1) will result in its direct release to the environment(SRC).|In both flooded and upland soils at 30 °C, 2-methyl-4-chlorophenoxybutyric acid, ethyl ester was rapidly degraded into 2-methyl-4-chlorophenoxybutyric acid, which was then slowly converted into 4-chloro-2-methylphenoxy acetic acid.

TERRESTRIAL FATE: Based on a classification scheme(1), a Koc value of 780 from a log Kow of 2.79(2), and a regression derived equation(3),indicates that 2-methyl-4-chlorophenoxybutyric acid is expected to have low mobility in soil(SRC). 2-Methyl-4-chlorophenoxybutyric acid is a weak acid with pKa of 4.84(4), which indicates that it will exist primarily as an anion in moist soils and anions will not volatilize(SRC). 2-Methyl-4-chlorophenoxybutyric acid is not expected to volatilize from dry soil surfaces(SRC) based upon its vapor pressure of 4.3X10-7 mm Hg(2). Half-lives of less than 7 days were determined for 2-methyl-4-chlorophenoxybutyric acid at an initial concn of 2 ug/g in a clay loam, heavy clay, and a sandy loam kept at about 85 percent field capacity moisture and 20 °C(5).|AQUATIC FATE: Based on a classification scheme(1), a Koc value of 780(SRC) from a log Kow of 2.79(2), and a regression derived equation(3)indicates that 2-methyl-4-chlorophenoxybutyric acid is expected to adsorb to suspended solids and sediment(SRC). 2-Methyl-4-chlorophenoxybutyric acid is a weak acid with pKa of 4.84(2), which indicates that it will exist primarily as an anion in water surfaces and anions will not volatilize(SRC). According to a classification scheme(5), an estimated BCF of 3(SRC), from its log Kow(2) and a regression-derived equation(6), suggests the potential for bioconcentration in aquatic organisms is low(SRC). Biodegradation half-lives of less than 7 days measured in soils(7), suggest that 2-methyl-4-chlorophenoxybutyric acid may also be susceptible to biodegradation in natural waters. Photolysis half-lives of 2-3 days were observed for 2-methyl-4-chlorophenoxybutyric acid in aqueous solutions exposed to sunlight(8), indicating photolysis in sunlit surface waters may be important(SRC).|ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), 2-methyl-4-chlorophenoxybutyric acid which has a vapor pressure of 4.3X10-7 mm Hg at 25 °C(2), is expected to exist in both the vapor and particulate-phases in the ambient atmosphere(SRC). Vapor-phase 2-methyl-4-chlorophenoxybutyric acid 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 19 hours(SRC), calculated from its rate constant of 2.0X10-11 cu cm/molecule-sec at 25 °C(SRC), that was derived using a structure estimation method(3). Particulate-phase 2-methyl-4-chlorophenoxybutyric acid will be removed from the atmosphere by wet or dry deposition(SRC). 2-Methyl-4-chlorophenoxybutyric acid underwent photolysis in aqueous exposed to sunlight(4) suggesting that photolysis in air may be possible(SRC).

The rate constant for the vapor-phase reaction of 2-methyl-4-chlorophenoxybutyric acid with photochemically-produced hydroxyl radicals has been estimated as 2.0X10-11 cu cm/molecule-sec at 25 °C(SRC) using a structure estimation method(1). This corresponds to an atmospheric half-life of about 19 hours at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm(1). 2-Methyl-4-chlorophenoxybutyric acid is stable to hydrolysis at pH 5-9, but photolyzed in laboratory water under optimal light exposure conditions with half-lives of approximately 2 to 3 days(2). Phototransformation products included 4-(4-hydroxy-o-tolyloxy)butyric acid, 2,4-dihyroxyphenyl formate, o-cresol, benzoic acid, and 2-hydroxyphenyl formate(2).

An estimated BCF of 3 was calculated in fish for 2-methyl-4-chlorophenoxybutyric acid(SRC), using a log Kow of 2.79(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).

537.03 L/kg|The Koc of 2-methyl-4-chlorophenoxybutyric acid is estimated as 780(SRC), using a log Kow of 2.79(1)and a regression-derived equation(2). According to a classification scheme(3), this estimated Koc value suggests that 2-methyl-4-chlorophenoxybutyric acid is expected to have low mobility in soil.

The pKa of 2-methyl-4-chlorophenoxybutyric acid is 4.84(1), which indicates that 2-methyl-4-chlorophenoxybutyric acid will exist primarily as an anion in moist soil and water surfaces(SRC). Volatilization of 2-methyl-4-chlorophenoxybutyric acid from water and moist soils will not occur since anions do not volatilize(SRC). 2-Methyl-4-chlorophenoxybutyric acid is not expected to volatilize from dry soil surfaces(SRC) based upon its vapor pressure of 4.3X10-7 mm Hg at 20 °C(2).

GROUNDWATER: 2-Methyl-4-chlorophenoxybutyric acid was identified, not quantified, in groundwater at unspecified locations in Austria(1).|SURFACE WATER: In 1977, 2-methyl-4-chlorophenoxybutyric acid was qualitatively identified in water from Lake Michigan(1). 2-Methyl-4-chlorophenoxybutyric acid was detected in 10 wetlands of the Saskatchewan region of Canada at an average concn of 6 ng/L(2), following a heavy rain event in July 2000(2). 2-Methyl-4-chlorophenoxybutyric acid was detected at a concn of 2 ng/L in natural spring water collected from the Saskatchewan region of Canada(3).

2-Methyl-4-chlorophenoxybutyric acid was not identified at a concn above 0.01 mg/kg between 1980 and 1985 in 354 vegetable composites from Ontario, Canada(1).

Occupational exposure to 2-methyl-4-chlorophenoxybutyric acid occurs through dermal contact and inhalation of dust and sprays, especially to workers applying the compound as a herbicide. (SRC)

Pesticides used to destroy unwanted vegetation, especially various types of weeds, grasses (POACEAE), and woody plants. Some plants develop HERBICIDE RESISTANCE. (See all compounds classified as Herbicides.)

... Can be absorbed percutaneously.

MCPB gave rise to 2-methyl-4-chlorophenoxyacetic acid when fed to dairy cows ... .|Guinea pigs were given oral doses of MCPB (40 mg), urine was collected & 2-methyl-4-chlorophenoxyacetic acid was found to be a formed metabolite of MCPB.

Information from the published literature ... concerning the mode of action of phenoxy herbicides indicates that they are systemic growth regulating hormones that act at multiple sites in a plant to disrupt hormone (auxin) balance and protein synthesis. The result is plant growth abnormalities. Uptake of phenoxy herbicides is said to be primarily through the foliage, but root and seed uptake are also said to occur.|Like 2,4-D, 4-MCPB is reputed to be an uncoupler of oxidative phosphorylation in mammalian tissues.

Follow-up clinical examination should include electromyographic and nerve conduction studies to detect any neuropathic changes and neuromuscular junction defects. /Chlorophenoxy herbicides/|Hemodialysis is not likely to be of significant benefit in poisonings by chlorophenoxy compounds. However, given the highly protein-bound nature of these herbicides and lack of any other evidence, hemodialysis is not recommended. /Chlorophenoxy herbicides/|Diuresis. Forced alkaline diuresis has been used successfully in management of suicidal ingestions of chlorophenoxy compounds, especially when initiated early. Alkalinizing the urine by including sodium bicarbonate (44 mEq per liter) in the intravenous solution accelerates excretion of 2,4-D dramatically and mecoprop excretion substantially. Urine pH should be maintained between 7.6 and 8.8. Include potassium chloride as needed to offset increased potassium losses: add 20-40 mEq of potassium chloride to each liter of intravenous solution. It is crucial to monitor serum electrolytes carefully, especially potassium and calcium. There may possibly be some hazard to the kidneys when urine concentrations of toxicant are very high, so the integrity of renal function and fluid balance should be monitored carefully as the chlorophenoxy compound is excreted. Renal failure has occurred in patients with severe intoxication during alkaline diuresis. In one case, the diuresis was begun 26 hours after ingestion, and the other two were initiated a couple days after poisoning. /Chlorophenoxy herbicides/|Intravenous fluids. Administer intravenous fluids to accelerate excretion of the chlorophenoxy compound, and to limit concentration of the toxicant in the kidney. A urine flow of 4-6 ml/minute is desirable. Intravenous saline/dextrose has sufficed to rescue comatose patients who drank 2,4-D and mecoprop several hours before hospital admission. Caution: Monitor urine protein and cells, BUN, serum creatine, serum electrolytes, and fluid intake/output carefully to insure that renal function remains unimpaired and that fluid overload does not occur. /Chlorophenoxy herbicides/|For more Antidote and Emergency Treatment (Complete) data for 2-METHYL-4-CHLOROPHENOXYBUTYRIC ACID (8 total), please visit the HSDB record page.

/SIGNS AND SYMPTOMS/ Severe eye irritant. Harmful or fatal if swallowed. /MCPB Technical/|/SIGNS AND SYMPTOMS/ Corrosive. Causes irreversible eye damage. Harmful if swallowed or inhaled. Avoid contact with skin or clothing. /Sodium MCPB/|/SIGNS AND SYMPTOMS/ Not particularly irritating to skin ... . Causes pain and irritation on eyes and mucous membranes.|/EPIDEMIOLOGY STUDIES/ The possible role of agricultural chemicals in the etiology of biliary tract cancer was investigated in rice farming regions of Japan. Mortality data on biliary tract cancers were obtained from the vital statistics of the Ministry of Health and Welfare of Japan. An environmental pollution index ... was derived by dividing the total amount of agricultural chemicals used annually within each prefecture by the area of the prefecture. Prefectures polluted with either of the herbicides 4-chloro-2-methyl-phenoxyacetic acid or 4-(4-chloro-2-methylphenoxy)butyric acid had the highest biliary tract cancer mortality rates. This effect was observed in males with 4-chloro-2-methyl-phenoxyacetic acid and in both sexes with 4-(4-chloro-2-methylphenoxy)butyric acid. These compounds were also associated with cancers of the pancreas in males and of the stomach in both sexes. There was a strong correlation between environmental pollution indices of 4-chloro-2-methyl-phenoxyacetic acid and deaths from biliary tract cancer within 5 to 9 years.|For more Human Toxicity Excerpts (Complete) data for 2-METHYL-4-CHLOROPHENOXYBUTYRIC ACID (6 total), please visit the HSDB record page.

2-methyl-4-chlorophenoxy gamma-butyric acid

Annual Pounds Used: Less than 15,000 pounds per year. Approximately 15 percent of green pea crops are treated with MCPB. Less than 2.5 percent of other types of pea crops are treated with MCPB.

MCPB (TECHNICAL GRADE) Active Ingredient 97.0% MCPB|MCPB TECHNICAL ACID Active Ingredient 95.5% MCPB|SODIUM MCPB HERBICIDE Active Ingredient 23.5% MCPB, sodium salt

The WHO Recommended Classification of Pesticides by Hazard identifies MCPB (technical grade) as Class III: slightly hazardous; Main Use: herbicide.|2,4-D, 2,4,5-T, MCPA, 2,4-DB, MCPB AND FENOPROP HAVE ALL BEEN USED AS WEEDKILLERS. THESE SUBSTANCES ARE PLANT HORMONES & ACT AS PLANT GROWTH REGULATORS RATHER THAN AS CONTACT POISONS.|CANADA THISTLE & OTHER BROADLEAF WEEDS (SUCH AS LAMBSQUARTERS, PIGWEED, SMARTWEED, SOW THISTLE, & ANNUAL MORNING GLORY) IN PEAS. GROUND & AERIAL FOLIAGE, SPRAYED OVERALL WHEN THISTLE SHOOTS HAVE EMERGED & ANNUAL BROADLEAF WEEDS ARE LESS THAN 3 INCHES HIGH, BUT NOT LATER THAN THREE NODES BEFORE PEA FLOWERING. ... 0.5 TO 1.5 LB ACID EQUIV/ACRE, DEPENDING ON WEEDS & STAGE OF GROWTH. FIVE TO 40 GALLON/ACRE WATER; 40 LB/SQ IN MAX PRESSURE. ... POSSIBLE INCOMPATIBILITY WITH HARD WATER. SHOULD NOT BE USED IN EXTREMELY HARD WATER.|USED /FOR CONTROL OF/ BROAD LEAVED ANNUAL AND PERENNIAL WEEDS IN UNDERSOWN CEREALS, PEAS, & ESTABLISHED GRASSLAND @ 1.7-3.4 KG ACID EQUIVALENT/HA. ... ACTION IS SELECTIVE ... .|For more General Manufacturing Information (Complete) data for 2-METHYL-4-CHLOROPHENOXYBUTYRIC ACID (7 total), please visit the HSDB record page.

RESIDUES: BY IR SPECTROPHOTOMETRY (RECOVERY MEASURED IN SITU BY ADDITION OF RADIOACTIVE HERBICIDE).|GLC BEHAVIOR OF CMPD INCL MCPB WAS STUDIED BY COMPARISON OF RETENTION INDICES.|2-Methyl-4-chlorophenoxybutyric acid ion selected for mass spectra quantitation of the herbicide in waste water and waste water sludges. GC analysis with detection by electron capture was also used. The degree and reproducibility of chlorophenoxy recovery were acceptable at 2.5 ug/g (with respect to dry solids) in a 50 ml sewage sludge sample and 5.0 ug/l in a 11 sewage sample.|A sensitive GLCmethod was developed for multiresidue analysis of 10 acid herbicides, incl MCPB, in sediment. Recoveries were better than 80% at the levels studied. Practical detection limits of this method were 10-25 ug/kg (ppb).|For more Analytic Laboratory Methods (Complete) data for 2-METHYL-4-CHLOROPHENOXYBUTYRIC ACID (7 total), please visit the HSDB record page.

Agrochemicals -> Herbicides|Herbicides|Environmental transformation -> Pesticides (parent, predecessor)|HERBICIDES

MCPB has known environmental transformation products that include MCPA and cloxyfonac.