디캄바

Pesticide -> EPA IRIS

Herbicides

Active substance -> EU Pesticides database: Approved

Pesticides -> Herbicides, Chlorophenoxy

Herbicides

Environmental transformation -> Pesticides (parent, predecessor)

log Kow = 2.21

2.21

3.01

1.57 g/cu cm at 25 °C

Relative density (water = 1): 1.57

Crystals from pentane

White granular solid; technical is a tight cream to tan solid

Crystalline solid, white (reference grade) or brown (technical grade)

In water, 8310 mg/L at 25 °C

In water, 6.6 (pH 1.8), >250 (pH 4.1, 6.6, 8.2) (all in g/L at 25 °C)

Water: 4500 mg/L at 25 °C. Solubility in organic solvents (g/100 mL at 25 °C): ethanol 92.2; heavy aromatic naphthanes 5.2; xylene 20.2; diacetone alcohol 91; acetone 126; dichloromethane 26; cyclohexanone 91.6; n-heane 0.375; methanol 137; carbon disulfide 127; chloroform 51.6; 1-octanol 68; tetrahydrofuran 139; dioxane 118; toluene 13; soluble in methyl ethyl ketone; insoluble in pentane

Very slightly soluble in water

For more Solubility (Complete) data for Dicamba (7 total), please visit the HSDB record page.

Solubility in water, g/100ml at 25 °C: 0.79

When heated to decomposition it emits toxic fumes of /chlorine/.

Dicamba decomposes in heat, producing toxic and corrosive fumes including hydrogen chloride.

Decomposes below boiling point at 200 °C.

200 °C

Danger

H302: Harmful if swallowed [Warning Acute toxicity, oral]

P261, P264, P264+P265, P270, P271, P273, P280, P301+P317, P304+P340, P305+P354+P338, P317, P319, P330, P391, P403+P233, P405, and P501 (click each P-code to see the statement)

Danger

H302+H332 (13.4%): Harmful if swallowed or if inhaled [Warning Acute toxicity, oral; acute toxicity, inhalation]

P261, P264, P264+P265, P270, P271, P273, P280, P301+P317, P304+P340, P305+P354+P338, P317, P319, P330, P391, P403+P233, P405, and P501 (click each P-code to see the statement)

Commission Regulation (EC) No 1490/2002

Reg. (EU) 2018/1796, Reg. (EU) 2019/1589, Reg. (EU) 2020/1511, Reg. (EU) 2021/1449, Reg. (EU) 2022/1480, Reg. (EU) 2023/2592, Reg. (EU) No 1100/2011, Reg. (EU) No 540/2011

Dicamba acid: HSNO Approval: HSR003321 Approved with controls

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.)

Class 9

Class 9

Not flammable. (USCG, 1999)

Excerpt from ERG Guide 171 [Substances (Low to Moderate Hazard)]:

Not combustible. Liquid formulations containing organic solvents may be flammable. Gives off irritating or toxic fumes (or gases) in a fire.

SOLID: Harmful if swallowed. (USCG, 1999)

Excerpt from ERG Guide 171 [Substances (Low to Moderate Hazard)]:

Oral LD50 (rats) = 757-1707 mg/kg. Dicamba is corrosive to the eyes and can cause skin burns. [EXTOXNET] The following herbicides have an oral LD50 of >1 gm/kg and have little or no acute toxicity in humans: Alachlor, Amitrole, Ammonium sulfamate, Atrazine, Dalapon, Dicamba, Glyphosphate, Monuron, Oryzalin, Picloram, Propanil, Simazine, etc. [LaDou, p. 613]

The major hazards encountered in the use and handling of dicamba stem from its toxicologic properties as an organochlorine herbicide. Contact with dicamba may cause burns to the skin and eyes. Results from animal testing have indicated that dicamba is a compound of low acute toxicity; however, effects of acute exposure to humans have been reported to include appetite loss, weight loss, vomiting, depression, muscular weakness, and even death if sufficient quantities are inhaled, ingested, or absorbed through the skin. Those involved in the manufacture, formulation and application of this pale, odorless, crystalline herbicide are at risk of exposure. Those at risk should wear boots, protective gloves, and goggles. Breathing dicamba dust is to be avoided and areas of the body that may have contacted dicamba should be washed with soap and water; particularly before smoking, eating, or using toilet facilities. Considered non-flammable, dicamba burns only with great difficulty. Therefore, any fire involving dicamba should be extinguished with agents suitable for use on surrounding materials. A positive-pressure breathing apparatus and special protective clothing should be worn under such emergency conditions. Fire control water should be diked to prevent its entering water sources and sewers. Dicamba is stable, and resistant to oxidation and hydrolysis under normal storage conditions. While no label is required for shipment, dicamba should be clearly identified in storage areas. Containers of dicamba may be shipped by air, rail, road, or water. Small liquid spills of dicamba may be reduced to solid phase by evaporation, and then removed by vacuum cleaning. Large land spills should be deposited in excavated pits, ponds or other holding areas that have been sealed with an impermeable flexible membrane liner. Surface flow should be diked with soil or sand bags. Spills of dicamba in bodies of water, first may need to be treated with activated carbon, then immobilized masses removed with mechanical dredges or lifts. Before permanent land disposal of dicamba, consult with environmental regulatory agencies.

Acids, Carboxylic

Acids, Carboxylic

USEPA/Office of Prevention, Pesticides and Toxic Substances; Reregistration Eligibility Decision Document - Dicamba and Associated Salts EPA 738-R-06-013 (June 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 USA.[EPA Docket No. EPA-HQ-OPP-2005-0479. Available from, as of June 19, 2017: https://www.regulations.gov/]

USEPA/Office of Pesticide Programs; Revised RED with Correction (June 17, 2009) (Regulatory Docket EPA-HQ-OPP-2005-0479).[Available from, as of June 21, 2017: http://www.regulations.gov]

Tolerances are established for the residues of the herbicide dicamba (3,6-dichloro-o-anisic acid), including its metabolites and degradates, in or on the commodities in the table below. Compliance with the tolerance levels is to be determined by measuring only the sum of the residues of dicamba (3,6-dichloro-o-anisic acid) and its metabolite, 3,6-dichloro-5-hydroxy-o-anisic acid, calculated as the stoichiometric equivalent of dicamba, in or on the following commodities:[Table#1017]

Tolerances are established for residues of the herbicide dicamba, 3,6-dichloro-o-anisic acid, including its metabolites and degradates, in or on the commodities in the table below. Compliance with the tolerance levels is to be determined by measuring only the residues of dicamba (3,6-dichloro-o-anisic acid) and its metabolite, 3,6-dichloro-2-hydroxybenzoic acid, calculated as the stoichiometric equivalent of dicamba, in or on the following commodities:[Table#1018]

Tolerances are established for residues of the herbicide dicamba, 3,6-dichloro-o-anisic acid, including its metabolites and degradates, in or on the commodities in the table below. Compliance with the tolerance levels is to be determined by measuring only the residues of dicamba, 3,6-dichloro-o-anisic acid, and its metabolites, 3,6-dichloro-5-hydroxy-o-anisic acid, and 3,6-dichloro-2-hydroxybenzoic acid, calculated as the stoichiometric equivalent of dicamba, in or on the following commodities:[Table#1019]

The Agency has completed its review of submitted data and its assessment of the dietary, residential, occupational, and ecological risks associated with the use of pesticide products containing the active ingredient dicamba. Based on these data, the Agency has sufficient information on the human health and ecological effects of dicamba to make its decision as part of the reregistration process under FIFRA, as amended by FQPA. The Agency has determined that products containing dicamba will be eligible for reregistration provided that (i) required product specific data are submitted, (ii) the risk mitigation measures outlined in this document are adopted, and (iii) label amendments are made to reflect these measures. ... Based on its evaluation of dicamba, the Agency has determined that dicamba products, unless labeled and used as specified in this document, would present risks inconsistent with FIFRA and FFDCA. Accordingly, should a registrant fail to implement any of the risk mitigation measures identified in this document, the Agency may take regulatory action to address the risk concerns from the use of dicamba. If all changes outlined in this document are incorporated into the product labels, then all current risks for dicamba will be adequately mitigated for the purposes of this interim determination under FIFRA. Additionally, once an endangered species assessment is completed, further changes to these registrations may be necessary as explained in Section IV.D.5.a of this document.

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 safety standards, such as those described in the Food Quality Protection Act of 1996. Dicamba 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: 0065; Pesticide type: Herbicide; Registration Standard Date: 09/30/83; 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 Reregistration Eligibility Decision (RED) document.; Active ingredient (AI): Dicamba; Data Call-in (DCI) Date(s): 04/22/92, 02/15/94, 03/03/95, 10/13/95; AI Status: OPP has completed a Reregistration Eligibility Decision (RED) document for the case/AI.

A halogenated benzoic acid derivative. Carboxylic acids donate hydrogen ions if a base is present to accept them. They react in this way with all bases, both organic (for example, the amines) and inorganic. Their reactions with bases, called "neutralizations", are accompanied by the evolution of substantial amounts of heat. Neutralization between an acid and a base produces water plus a salt. Carboxylic acids with six or fewer carbon atoms are freely or moderately soluble in water; those with more than six carbons are slightly soluble in water. Soluble carboxylic acids dissociate to an extent in water to yield hydrogen ions. The pH of solutions of carboxylic acids is therefore less than 7.0. Many insoluble carboxylic acids react rapidly with aqueous solutions containing a chemical base and dissolve as the neutralization generates a soluble salt. Carboxylic acids in aqueous solution and liquid or molten carboxylic acids can react with active metals to form gaseous hydrogen and a metal salt. Such reactions occur in principle for solid carboxylic acids as well, but are slow if the solid acid remains dry. Even "insoluble" carboxylic acids may absorb enough water from the air and dissolve sufficiently in it to corrode or dissolve iron, steel, and aluminum parts and containers. Carboxylic acids, like other acids, react with cyanide salts to generate gaseous hydrogen cyanide. The reaction is slower for dry, solid carboxylic acids. Insoluble carboxylic acids react with solutions of cyanides to cause the release of gaseous hydrogen cyanide. Flammable and/or toxic gases and heat are generated by the reaction of carboxylic acids with diazo compounds, dithiocarbamates, isocyanates, mercaptans, nitrides, and sulfides. Carboxylic acids, especially in aqueous solution, also react with sulfites, nitrites, thiosulfates (to give H2S and SO3), dithionites (SO2), to generate flammable and/or toxic gases and heat. Their reaction with carbonates and bicarbonates generates a harmless gas (carbon dioxide) but still heat. Like other organic compounds, carboxylic acids can be oxidized by strong oxidizing agents and reduced by strong reducing agents. These reactions generate heat. A wide variety of products is possible. Like other acids, carboxylic acids may initiate polymerization reactions; like other acids, they often catalyze (increase the rate of) chemical reactions.

DICAMBA is a chlorinated benzoic acid derivative. Reacts as a weak acid to neutralize bases, both organic (for example, the amines) and inorganic. May corrode iron, steel, and aluminum parts and containers if moist. Reacts with cyanide salts in the presence of moisture to generate gaseous hydrogen cyanide. May react if moist with sulfites, nitrites, thiosulfates (to give H2S and SO3), dithionites (SO2), to generate flammable and/or toxic gases and heat. Can be oxidized by strong oxidizing agents and reduced by strong reducing agents. These reactions generate heat. A wide variety of products is possible. Like other acids, may initiate polymerization reactions or catalyze other reactions.

Excerpt from ERG Guide 171 [Substances (Low to Moderate Hazard)]:

Excerpt from ERG Guide 171 [Substances (Low to Moderate Hazard)]:

In case of fire in the surroundings, use appropriate extinguishing media.

Fresh air, rest. Refer for medical attention.

Remove contaminated clothes. 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.

Rinse mouth. Refer for medical attention .

EYES: Flush with water; obtain medical attention.

Excerpt from ERG Guide 171 [Substances (Low to Moderate Hazard)]:

Suitable extinguishing media: Use water spray, alcohol-resistant foam, dry chemical or carbon dioxide.

Advice for firefighters: Wear self contained breathing apparatus for fire fighting if necessary.

If material involved in fire: Extinguish fire using agent suitable for type of surrounding fire. Material itself does not burn, or burns with difficulty.

This chemical is a noncombustible solid. Use extinguishers suitable for surrounding fire ... If material or contaminated runoff enters waterways, notify downstream users of potentially contaminated waters. Notify local health and fire officials and pollution control agencies. From a secure, explosion-proof location, use water spray to cool exposed containers. If cooling streams are ineffective (venting sound increases in volume and pitch, tank discolors or shows any signs of deforming), withdraw immediately to a secure position ... The only respirators recommended for fire fighting are self-contained breathing apparatuses that have full facepieces and are operated in a pressure-demand or other positive-pressure mode.

Keep container tightly closed in a dry and well-ventilated place.

Store in tightly closed containers in a cool, well-ventilated area away from incompatible materials ..., heat and water.

Store above 15 °F.

ACCIDENTAL RELEASE MEASURES: Personal precautions, protective equipment and emergency procedures. Use personal protective equipment. Avoid dust formation. Avoid breathing vapors, mist or gas. Ensure adequate ventilation. Evacuate personnel to safe areas. Avoid breathing dust. Environmental precautions: Prevent further leakage or spillage if safe to do so. Do not let product enter drains. Discharge into the environment must be avoided. Methods and materials for containment and cleaning up: Pick up and arrange disposal without creating dust. Sweep up and shovel. Keep in suitable, closed containers for disposal.

Spill handling: Evacuate persons not wearing protective equipment from area of spill or leak until cleanup is complete. Remove all ignition sources. Collect powdered material in the most convenient and safe manner and deposit in sealed containers. Ventilate area after clean-up is complete. It may be necessary to contain and dispose of this chemical as a hazardous waste. If material or contaminated runoff enters waterways, notify downstream users of potentially contaminated waters. Contact your Department of Environmental Protection or your regional office of the federal EPA for specific recommendations.

Environmental considerations: Land spill: Dig a pit, pond, lagoon, or holding area to contain liquid or solid material. Cover solids with a plastic sheet to prevent dissolving in rain or fire fighting water. /SRP: If time permits, pits, ponds, lagoons, soak holes or holding areas used to contain the chemical should be sealed with a impermeable flexible membrane liner./

Environmental consideration: Water spill: If dissolved, in region of 10 ppm or greater concentration, apply activated carbon at ten times the spilled amount. Use mechanical dredges or lifts to remove immobilized masses of pollutants and precipitates.

Contain liquid spill with absorbent material, collect in a suitable waste container. Wash affected area with water and detergent. Keep wash water out of drains.

Excerpt from ERG Guide 171 [Substances (Low to Moderate Hazard)]:

Excerpt from ERG Guide 171 [Substances (Low to Moderate Hazard)]:

SRP: 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 air, soil or water; effects on animal, aquatic and plant life; and conformance with environmental and public health regulations. If it is possible or reasonable use an alternative chemical product with less inherent propensity for occupational harm/injury/toxicity or environmental contamination.

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.

Product: Offer surplus and non-recyclable solutions to a licensed disposal company. Contact a licensed professional waste disposal service to dispose of this material. Contaminated packaging: Dispose of as unused product.

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. ... For guidance contact your State Water Board or Regional Office of the EPA.

For more Disposal Methods (Complete) data for Dicamba (9 total), please visit the HSDB record page.

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

ACCIDENTAL RELEASE MEASURES: Personal precautions, protective equipment and emergency procedures. Use personal protective equipment. Avoid dust formation. Avoid breathing vapors, mist or gas. Ensure adequate ventilation. Evacuate personnel to safe areas. Avoid breathing dust. Environmental precautions: Prevent further leakage or spillage if safe to do so. Do not let product enter drains. Discharge into the environment must be avoided.

Precautions for safe handling: Avoid contact with skin and eyes. Avoid formation of dust and aerosols. Provide appropriate exhaust ventilation at places where dust is formed.

Appropriate engineering controls: Handle in accordance with good industrial hygiene and safety practice. Wash hands before breaks and at the end of workday.

Gloves must be inspected prior to use. Use proper glove removal technique (without touching glove's outer surface) to avoid skin contact with this product. Dispose of contaminated gloves after use in accordance with applicable laws and good laboratory practices. Wash and dry hands.

For more Preventive Measures (Complete) data for Dicamba (18 total), please visit the HSDB record page.

... Pretreatment of wild garlic (Allium vineale L) shoots with low concentration of 2-chloroethylphosphonic acid ... increased basipetal translocation of foliar-applied dicamba. Pretreatment of excised bean leaves with endothall (7-oxabicylo-(2,2,1)heptane-2,3-dicarboxylic acid) greatly reduced subsequent dicamba vein loading and transport. Polar transport was activated by ATP and inhibited by 2,4-dinitrophenol (DNP). Dicamba uptake and retention were increased either by addition of 2% sucrose or by prior exposure of plants to sunlight.

Antagonistic responses between carbamate herbicides and dicamba have ... /shown/ that dicamba-induced soybean hypocotyl elongation and curvature were inhibited in presence of ... chlorpropham ... or EPTC (S-ethyl dipropylthiocarbamate), and that S-ethyl dipropylthiocarbamate injury to sorghum was ... reduced in presence of dicamba. Synergistic responses between dicamba and several phenoxy herbicides have ... been reported ... .

... Dicamba metabolism by way of 5-OH-dicamba conjugation ... was significantly inhibited by 1x10-5 molar concn of several organophosphate insecticides.

Greenhouse studies were conducted to determine the basis for reduced johnsongrass control when glyphosate was applied in mixtures with 2,4-D or dicamba. Glyphosate was applied to johnsongrass at 0.28, 0.56, 0.84, and 1.12 kg/ha alone and in combination with 2,4-D or dicamba at 0.14, 0.28, 0.14, or 0.56 kg/ha. Johnsongrass shoot and root fresh weights measured 4 weeks after treatment were higher when glyphosate was applied with 2,4-D (0.28 kg/ha glyphosate) or dicamba (0.28 kg/ha or 0.56 kg/ha glyphosate) compared to glyphosate applied alone at these rates. The antagonism of johnsongrass control was not observed with combinations of some of the higher glyphosate rates with 2,4-D (0.56 or 0.84 kg/ha glyphosate) or dicamba (0.84 or 1.12 kg/ha glyphosate). The reduction of glyphosate activity on johnsongrass occurred when any of four forms of 2,4-D or two forms of dicamba were added to the glyphosate spray mixture. Glyphosate uptake intake into johnsongrass leaves and subsequent translocation to the roots was reduced by the presence of 2,4-D or dicamba. The reduced glyphosate uptake and translocation could account for the decreased toxicity of glyphosate to johnsongrass when applied with 2,4-D or dicamba.

For more Interactions (Complete) data for Dicamba (7 total), please visit the HSDB record page.

In oral, dermal, and inhaled routes of exposure, dicamba has a low acute toxicity. Dicamba may have irritating or corrosive effects on the skin and eyes. The EPA has identified dicamba as a developmental toxin in the Toxics Release Inventory. (L2156)

LD50; Species: Colinus virginianus (Bobwhite quail); oral (gavage, single dose) 968 mg/kg (95% confidence intervaI: 644-1615 mg/kg) /Dicamba, diglycolamine salt; 56.8% a.i./

LD50; Species: Colinus virginianus (Bobwhite quail) oral (diet over 5 days) >5620 mg/kg /Dicamba, diglycolamine salt; 56.8% a.i./

LD50; Species: Colinus virginianus (Bobwhite quail) oral (gavage) 1373 mg/kg (95% confidence interval: 1105-1716 mg/kg) /Dicamba, isopropylamine salt/

LD50; Species: Anas platyrhynchos (Mallard duck) oral (gavage) 1373 mg/kg (95% confidence interval: 1105-1716 mg/kg) /86.93% a.i. technical/

For more Ecotoxicity Values (Complete) data for Dicamba (30 total), please visit the HSDB record page.

TERRESTRIAL FATE: Based on a classification scheme(1), Koc values of 3.45-34(2-3) indicate that dicamba is expected to have very high mobility in soil(SRC). The pKa of dicamba is 1.97(4), indicating that this compound will exist almost entirely in the anion form in the environment and anions generally do not adsorb more strongly to soils containing organic carbon and clay than their neutral counterparts(5). Volatilization of the anion from moist soil is not expected because anions do not volatilize(SRC). Over a 154-day observation period, 0.6-7.9% of soil applied dicamba volatilized with the highest volatilization rates at high (35 °C) soil temperatures(6). Dicamba is not expected to volatilize from dry soil surfaces(SRC) based upon a vapor pressure of 1.25X10-5 mm Hg at 25 °C(2). Aerobic soil metabolism is the main degradative process with the formation of 3,6-dichlorosalicylic acid; metabolism in anaerobic soil is similar to aerobic soil with the same formation of 3,6-dichlorosalicylic acid but slower(7). The persistence of dicamba in agricultural soils is highly variable and depends on factors such as application rates, moisture content, temperature, pH and soil type(6). Field dissipation half-lives have been reported as 7.9-592 days under varying conditions(8). Under anaerobic conditions, half-lives of 58-141 days have been observed(2,9). A photodegradation half-life equivalent to 269 days (40 deg N latitude, springtime sunlight at noon) was determined suggesting that field dissipation due to direct photolysis is negligible(10).

TERRESTRIAL FATE: The degradation first order rate constant and half-life of dicamba in various landscape soils at two different depths were reported as follows(1):[Table#1016]

AQUATIC FATE: Based on a classification scheme(1), Koc values of 3.45-34(2-3) indicate that dicamba is not expected to adsorb to suspended solids and sediment(SRC). A pKa of 1.97(4) indicates dicamba will exist almost entirely in the anion form at pH values of 5 to 9 and, therefore, volatilization from water surfaces is not expected to be an important fate process(SRC). In water, dicamba is stable to abiotic hydrolysis(5) and photodegrades slowly(5-6). According to a classification scheme(7), an estimated BCF of 3(SRC), from its log Kow of 2.21(8) and a regression-derived equation(9), suggests the potential for bioconcentration in aquatic organisms is low. In an aquatic ecosystem study, dicamba did not bioaccumulate in algae, clam, crab, daphnia, elodea, mosquito fish, mosquito larvae or snail over a 32-day test period(10). In nonsterile water, 16% of applied dicamba disappeared after 133 days while only 5% disappeared in sterile water suggesting the importance of microbial decomposition(6).

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), dicamba, which has a vapor pressure of 1.25X10-5 mm Hg at 25 °C(2), will exist in both the vapor and particulate phases in the ambient atmosphere. Vapor-phase dicamba 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 5.4 days(SRC), calculated from its rate constant of 2.98X10-12 cu cm/molecule-sec at 25 °C(SRC) that was derived using a structure estimation method(3). Particulate-phase dicamba has been observed to be removed from the air by wet and dry deposition(4). Dicamba contains chromophores that absorb at wavelengths >290 nm(5) and, therefore, may be susceptible to direct photolysis by sunlight(SRC).

As part of the US FDA's 1990 Total Diet Study of residues in US foods, dicamba was reported as detected (no concentrations, detection limits or specific food samples reported)(1). During a 1980-1985 survey of Ontario-grown vegetables, dicamba was detected in one of seven potato samples at a mean concentration of 0.02 ppm and in one of twelve tomato samples at a concentration of 0.03 ppm(2).

The substance can be absorbed into the body by ingestion.

Oral; inhalation; dermal

IDENTIFICATION AND USE: Dicamba is a crystalline solid, white (reference grade) or brown (technical grade). It is a growth regulating herbicide. It controls broadleaf weeds in asparagus, corn (field, silage, popcorn), grass seed crops, grain sorghum, noncropland, pastures, rangeland, reduced-tillage, fallow, small grains not underseeded to legumes, sugarcane, turf, between cropping; brush and vines in pastures, industrial areas, noncropland, rangeland; perennial broadleaf weeds with spot treatments and ropewick applications. HUMAN STUDIES: Dicamba is moderately toxic by ingestion and slightly toxic by inhalation or dermal exposure. Symptoms of poisoning with dicamba include loss of appetite (anorexia), vomiting, muscle weakness, slowed heart rate, shortness of breath, central nervous system effects (victim may become excited or depressed), benzoic acid in the urine, incontinence, cyanosis (bluing of the skin and gums), and exhaustion following repeated muscle spasms. In addition to these symptoms, inhalation can cause irritation of the linings of the nasal passages and the lungs, and loss of voice. Most individuals who have survived severe poisoning from dicamba have recovered within 2 to 3 days with no permanent effects. Dicamba is capable of inducing DNA damage since it significantly increases the unwinding rate for liver DNA in vivo and also induces unscheduled DNA synthesis in human peripheral blood lymphocytes in vitro in the presence of exogenous metabolic activation. Furthermore, dicamba causes a very slight increase in sister chromatid exchange frequency in human peripheral blood lymphocytes in vitro. ANIMAL STUDIES: In rabbits, dose-related dermal irritation was observed. Desquamation was seen predominantly in the 1000 mg/kg/day group while moderate erythema, moderate edema and atonia were observed exclusively in the 1000 mg/kg/day group. Technical dicamba was fed in diet to rats (60/sex/group) at 0, 50, 250 or 2500 ppm in the diet for 115 to 118 weeks. Brain ventricular dilatation associated with pituitary anterior adenomas were observed in females at >/= 250 ppm. Adrenal enlargement was increased at >/= 250 ppm in both sexes. Increased macroscopic lesions in liver at >/= 250 ppm (males) and lesions in lymph nodes at 2500 ppm (males) were observed. There were increased malignant lymphomas in females at >/= 250 ppm, increased parafollicular cell carcinoma, and adenoma, as well as increased follicular adenoma and carcinomas in treated males, primarily at 2500 ppm, but could be extended down to the lower doses. Chronic treatment of adult and newborn rats with less than 0.04xLD50 of dicamba caused disorder of oxidative phosphorylation and focal necrosis in the heart. Similar changes were observed in rat embryos of dams exposed to the pesticide. In a rat developmental study, no treatment-related fetotoxicity or developmental effects were observed at any dose level based on assessments of numbers of pregnancies, implantation and resorption sites, and viable and dead fetuses, as well as litter weights and external, skeletal and visceral fetal examinations. Dicamba was negative in the Ames test with Salmonella typhimurium TA98, TA100, TA1535, TA1537 and TA102 with or without activation. ECOTOXICITY STUDIES: In fish, dicamba exposure could result in histological lesions, plasma vitellogenin increases, changes in sex hormone levels, and alterations of hormone-related gene expression. Dicamba induced primary DNA breaks in amphibians. Dicamba significantly increased lady beetle mortality and reduced their body weight. Plants exposed to sublethal levels of dicamba may produce fewer floral resources and be less frequently visited by pollinators.

/BIRDS and MAMMALS/ Bobwhite quail (Colinus virginianus) were given dicamba, DGA salt, technical (The test material is identified on label as 4 lb/gal diglycolamine salt of dicamba (percent a.i. not reported). This is presumably Vanquish, which is 56.8% a.i. and 38.5% acid equivalents.) by gavage, dispersed in water, single dose, and observed for 14 days. LD50 = 968 mg/kg (95% CI = 644-1615) corresponding to 372 mg acid equivalents/kg. No mortality level = Not identified. LOEL = 292 mg/kg (112 mg acid equivalents/kg). NOEL = Not identified (< 292 mg/kg). Signs of toxicity at the LOEL were mainly neurotoxic and included lower limb weakness and rigidity, loss of coordination, reduced reaction to external stimuli, lethargy and/or prostate posture; surviving birds recovered by days 4-6. /Dicamba, diglycolamine salt/

/BIRDS and MAMMALS/ Bobwhite quail (Colinus virginianus) were given dicamba, DGA salt (The test material is identified on label as 4 lb/gal diglycolamine salt of dicamba (percent a.i. not reported). This is presumably Vanquish, which is 56.8% a.i. and 38.5% a.e.) in their diet for 5 days and observed for 3 days. LD50 > 5620 ppm. NOEL = 5620 ppm (highest level tested, no deaths or overt signs of toxicity). Average food intake and body weight during dosing period at NOEL were 9 g food/bird/day and 30 g bw. The NOAEL of 5620 ppm corresponds to a dose of 1686 mg/kg/day based on food consumption data or 650 mg a.e./kg. /Dicamba, diglycolamine salt/

/BIRDS and MAMMALS/ Bobwhite quail (Colinus virginianus) were given a single dose by gavage of dicamba, isopropylamine salt (32.3% a.e.), dispersed in water and observed for 14 days. LD50 = 1373 mg/kg (95% CI = 1105-1716) corresponding to about 440 mg/kg a.e. No mortality level = 810 mg/kg (261 mg a.e./kg). LOEL = 292 mg/kg (signs of neurotoxicity) (94 mg a.e./kg). NOEL = Not identified (<292 mg/kg). /Dicamba, isopropylamine salt/

/BIRDS and MAMMALS/ Bobwhite quail (Colinus virginianus) were given technical dicamba (86.9% a.i.) in corn oil for 21 weeks in a one generation reproduction study. NOEL = 1600 ppm (highest level tested). No exposure-related deaths, overt signs of toxicity, or effects on body weight, feed consumption or reproductive endpoints (egg production and quality, embryo viability, and hatchling health and 14 day survivability). Based on measured food consumption (about 10.5% of body weight), the dietary NOAEL corresponds to a dose of 170 mg/kg bw.

For more Ecotoxicity Excerpts (Complete) data for Dicamba (25 total), please visit the HSDB record page.

Tolerances are established for the residues of the herbicide dicamba (3,6-dichloro-o-anisic acid), including its metabolites and degradates, in or on the commodities in the table below. Compliance with the tolerance levels is to be determined by measuring only the sum of the residues of dicamba (3,6-dichloro-o-anisic acid) and its metabolite, 3,6-dichloro-5-hydroxy-o-anisic acid, calculated as the stoichiometric equivalent of dicamba, in or on the following commodities:[Table#1017]

Tolerances are established for residues of the herbicide dicamba, 3,6-dichloro-o-anisic acid, including its metabolites and degradates, in or on the commodities in the table below. Compliance with the tolerance levels is to be determined by measuring only the residues of dicamba (3,6-dichloro-o-anisic acid) and its metabolite, 3,6-dichloro-2-hydroxybenzoic acid, calculated as the stoichiometric equivalent of dicamba, in or on the following commodities:[Table#1018]

Tolerances are established for residues of the herbicide dicamba, 3,6-dichloro-o-anisic acid, including its metabolites and degradates, in or on the commodities in the table below. Compliance with the tolerance levels is to be determined by measuring only the residues of dicamba, 3,6-dichloro-o-anisic acid, and its metabolites, 3,6-dichloro-5-hydroxy-o-anisic acid, and 3,6-dichloro-2-hydroxybenzoic acid, calculated as the stoichiometric equivalent of dicamba, in or on the following commodities:[Table#1019]

The Agency has completed its review of submitted data and its assessment of the dietary, residential, occupational, and ecological risks associated with the use of pesticide products containing the active ingredient dicamba. Based on these data, the Agency has sufficient information on the human health and ecological effects of dicamba to make its decision as part of the reregistration process under FIFRA, as amended by FQPA. The Agency has determined that products containing dicamba will be eligible for reregistration provided that (i) required product specific data are submitted, (ii) the risk mitigation measures outlined in this document are adopted, and (iii) label amendments are made to reflect these measures. ... Based on its evaluation of dicamba, the Agency has determined that dicamba products, unless labeled and used as specified in this document, would present risks inconsistent with FIFRA and FFDCA. Accordingly, should a registrant fail to implement any of the risk mitigation measures identified in this document, the Agency may take regulatory action to address the risk concerns from the use of dicamba. If all changes outlined in this document are incorporated into the product labels, then all current risks for dicamba will be adequately mitigated for the purposes of this interim determination under FIFRA. Additionally, once an endangered species assessment is completed, further changes to these registrations may be necessary as explained in Section IV.D.5.a of this document.

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 safety standards, such as those described in the Food Quality Protection Act of 1996. Dicamba 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: 0065; Pesticide type: Herbicide; Registration Standard Date: 09/30/83; 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 Reregistration Eligibility Decision (RED) document.; Active ingredient (AI): Dicamba; Data Call-in (DCI) Date(s): 04/22/92, 02/15/94, 03/03/95, 10/13/95; AI Status: OPP has completed a Reregistration Eligibility Decision (RED) document for the case/AI.

Persons in charge of vessels or facilities are required to notify the National Response Center (NRC) immediately, when there is a release of this designated hazardous substance, in an amount equal to or greater than its reportable quantity of 1,000 lb or 454 kg. The toll free number of the NRC is (800) 424-8802. The rule for determining when notification is required is stated in 40 CFR 302.4 (section IV. D.3.b).

Dicamba is designated as a hazardous substance under section 311(b)(2)(A) of the Federal Water Pollution Control Act and further regulated by the Clean Water Act Amendments of 1977 and 1978. These regulations apply to discharges of this substance. This designation includes any isomers and hydrates, as well as any solutions and mixtures containing this substance.

(AZ) ARIZONA 9 ug/L

(FL) FLORIDA 210 ug/L

(MN) MINNESOTA 200 ug/L

(WI) WISCONSIN 300 ug/L

In plants, dicamba mimics auxin plant growth hormones and causes uncontrolled growth. This hormonal mode of action is specific to plants and does not affect animals.

Dicamba has been shown to induce hepatic peroxisomal enzymes and activate the peroxisomal proliferator activator receptor (PPAR) in rats, suggesting that it might have liver tumor promoting activity similar to other peroxisomal proliferators. This hypothesis was not supported by testing with the two-stage hepatocarcinogenesis model in rats, which found that dicamba was inactive as a tumor promoter.

The plasma kinetics of dicamba were investigated in orally-exposed rats ... Plasma initial half-life, which similarly increased at doses above 150 mg/kg in male Wistar rats (to 2.6-5.4 hr), 150 mg/kg in female Wistar rats (to 4.8-6.0 hr), 125 mg/kg in male Sprague-Dawley rats (to 2.8-12.4 hr), and 250 mg/kg in female Sprague-Dawley rats (to 1.7-4.4 hr).

... dicamba /was/ dissolved in acetone and applied to shaved skin /of rats/ (6 sq cm, 0.8 or 4.1 mg/sq cm), and covered with plastic film ... The half-time in blood /was/ 0.4 hr for dicamba.

The distribution and elimination of dicamba and another isomer present in its formulation, 3,5-dichloro-2-methoxybenzoic acid were studied in rats following single iv injections. The elimination of dicamba from the blood was rapid with a biological half-life of 0.64 hours, (following 100 mg/kg), while the elimination of the isomer from the blood was much slower with a biological half-life of 16.5 hr, (following 20 mg/kg).

The oral absorption of dicamba has been quantified in urinary excretion studies ... A mixture of (14)C-labeled dicamba (98% pure) and technical dicamba /was administered/ to Charles River CD rats by a single gavage dose in peanut oil (0.1 and 0.9 g/kg), via diet (10-20,000 ppm) for 24 hr, or by a single sc injection in peanut oil (0.1 g/kg). Following gavage or subcutaneous exposure, approximately 93% and 96% of the administered (14)C-dicamba, respectively, was excreted unmetabolized in the urine within 24 hr of dosing. With dietary exposure, urinary and fecal excretion approached 96% and 4% of the rate of intake. Dicamba was excreted unchanged in the urine (20% was conjugated with glucuronic acid). Similarly, following a single oral dose of 100 mg/kg of (14)Cdicamba (99% pure) in rats, mice, rabbits, and dogs, 67-83% of the radioactivity was eliminated in the urine as parent compound within 48 hr. About 1% of the administered dose was metabolized to 3,6-dichlorosalicylic acid (3,6-DCSA or 3,6-dichloro-2-hydroxybenzoic acid) and another 1% to an unidentified metabolite.

While there are no studies available to evaluate the estimated dermal permeability coefficient for dicamba, the estimated first-order dermal absorption rate in humans can be compared to the first order dermal absorption rate determined in rats ... In this study, both dicamba and 3,5-dichloro isomer were dissolved in acetone and applied to shaved skin (6 sq cm, 0.8, or 4.1 mg/sq cm), and covered with plastic film. The highest blood concentrations of dicamba and isomer were found at 1 and 9 hr, respectively ... The disappearance of both chemicals from the blood followed first order kinetics, and findings for combined exposure were similar to that for the individual chemicals. The half-times in blood were 0.4 hr for dicamba and 3.6 hr for the isomer, suggesting that dermal absorption was the rate limiting step in urinary elimination of the isomer. As estimated from urinary excretion, 14.1 and 7.5% of the applied dermal doses of dicamba and isomer were absorbed. The absorption rates through the skin were 0.0029/ hr for dicamba and 0.0012/ hr for the isomer. /Dicamba, 3,5-dichloro isomer/

... There are two major plant metabolites 3,6-dichloro-5-hydroxybenzoic acid (5-OH dicamba) and 3,6-dichlorosalicylic acid (DCSA), which are structurally similar to the parent compound ...

Metabolism of dicamba by wheat (Var gaines) and bluegrass (Var newport) plants yielded 3 metabolites. GLC, infrared and mass spectrometry were used to identify the major (90%) metabolite as 5-hydroxy-2-methoxy-3,6-dichlorobenzoic acid. After hydrolysis by beta glucosidase, one of minor (5%) residues was ... dicamba. Second minor (5%) metabolite was ... 3,6-dichlorobenzoic acid. The data indicated that 5-hydroxy-dicamba and 3,6-dichlorogentisic acid were major metbolites in young barley plants treated with dicamba.

For more Metabolism/Metabolites (Complete) data for Dicamba (11 total), please visit the HSDB record page.

Toxicokinetics and recovery studies of dicamba dimethyl amine salt (DDAS) were conducted to obtain more information about its toxicity and tissue retention in farm animals. The minimum oral toxic dose level of DDAS was determined as 1400 mg/kg body weight. In the toxicokinetic study, blood DDAS concentration of 55.6 +/- 0.59 ug/mL (mean +/- standard error) was detected at 0.08 hr, which peaked to 102.3 +/- 5.03 ug/mL at 0.25 hr, and declined to a minimum of 4.1 +/- 0.06 ug/mL at 36 hr. In recovery studies, DDAS concentration in urine began to increase significantly (P < 0.05) from 12 hr, peaked at 24 hr and declined from 48 hr onwards. Maximum excretion through feces was at 24 hr and was complete by 144 hr. The residual level in tissues decreased significantly (P < 0.05) on day 7 as compared to day 4. In histopathological studies, cellular alterations in lungs, liver, kidney, adrenal gland and spleen were found. DDAS persists in the body for a shorter period and its major excretory route is through urine. DDAS has lower affinity to accumulate in tissues, and intensity of cellular alterations is not severe after single-dose oral administration. /Dicamba dimethyl amine salt/

In a plasma pharmacokinetic study, five groups of 4 male and 4 female Wistar rats received diets containing the equivalent of 50, 100, 200, 400, or 800 mg/kg dicamba/day for 90 days (Lot No. 52103810, 87.2% a.i.) . On study days 29, 63, and 91, dietary supplementation of dicamba was stopped and rats in each group received an equivalent gavage dose of (14)C-dicamba (Lot No. 787-0102, >99% a.i., universally labeled in the phenyl group). Blood samples were drawn 0.5, 1, 2, 4, 6, 8, 12, 24, and 48 hr after treatment and the plasma radioactivity determined. Absorption of the radiolabeled test material was rapid, with peak plasma concentrations found within 2 hr of treatment. Absorption was not saturated, even at the highest dose, as indicated by increasing plasma concentrations with dose. However, the increase in plasma concentration was disproportionate from dose as shown by the >/= 2-fold increase in AUC from one dose group to the next at doses > 100 mg/kg. Elimination of radiolabel from the plasma was tri-phasic, with the terminal-phase consistent between doses. However, the initial elimination phase increased with dose, particularly in the 400 and 800 mg/kg dose groups and is consistent with excretion saturation. No significant treatment-related differences between the sexes or time of radiolabel administration were found.

In a pharmacokinetic study, two groups of 3 male Wistar rats were given a single 200 mg/kg gavage dose of (14)C-dicamba (Lot No. 787-0102, > 99% a.i., universally labeled in the phenyl group). One group of rats was pretreated with a 150 mg/kg IP dose of probenecid , a known competitive inhibitor of renal anion transport, 30 min prior to dicamba dosing. Blood samples were drawn 0.5, 1, 2, 4, 6, 8, 12, 24, and 48 hr after gavage treatment and the plasma radioactivity determined. The time to peak plasma concentration in rats treated with (14)C-dicamba occurred within 0.5 hr while peak plasma concentration was reached at 1.0 hr in the probenecid/dicamba rats. However, pretreatment with probenecid increased plasma AUC by a factor of 1.54. Although the terminal phase of elimination remained relatively the same, the initial and intermediate elimination phases were increased by a factor of two. These data suggest that both dicamba and probenecid act as inhibitors of renal anion transport.

Dicamba is rapidly and extensively absorbed following oral exposure and rapidly excreted predominantly as unmetabolized compound in the urine. Oral studies in rats indicate that there are no significant pharmacokinetic differences in the free acid and amine salt forms of dicamba. Dermal absorption of dicamba has been demonstrated but is less well studied than oral absorption.

For more Absorption, Distribution and Excretion (Complete) data for Dicamba (18 total), please visit the HSDB record page.

Used as a herbicide applied to leaves or soil to control broadleaf weeds; [EXTOXNET]

Farming (Pesticides) [Category: Industry]

For dicamba (USEPA/OPP Pesticide Code: 029801) 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./

Growth regulating herbicide.

Control broadleaf weeds in asparagus, corn (field, silage, popcorn), grass seed crops, grain sorghum, noncropland, pastures, rangeland, reduced-tillage, fallow, small grains not underseeded to legumes, sugarcane, turf, between cropping; brush and vines in pastures, industrial areas, noncropland, rangeland; perennial broadleaf weeds with spot treatments and ropewick applications.

Dicamba is an herbicide. Dicamba controls annual and perennial rose weeds in grain crops and highlands, and it is used to control brush and bracken in pastures, as well as legumes and cacti. (L371)

Technical grade purity is 85% with the remainder being mainly 3,5-dichloro-o-anisic acid

The major impurity in technical grade dicamba is 3,5-dichloro-2-methoxy benzoic acid.

(1975) 1.36X10+9 G

(1984) 1.37X10+7 g /used in California/

(1991) Exceeded 5000 lb

Non-confidential 2012 Chemical Data Reporting (CDR) information on the production and use of chemicals manufactured or imported into the United States. Chemical: Benzoic acid, 3,6-dichloro-2-methoxy-. National Production Volume: 615,060 lb/yr.

Non-confidential 2016 Chemical Data Reporting (CDR) information on the production and use of chemicals manufactured or imported into the United States. Chemical: Benzoic acid, 3,6-dichloro-2-methoxy-:

60% AS AN HERBICIDE FOR CORN; 20% AS AN HERBICIDE FOR WHEAT; AND 20% FOR MISC APPLICATIONS (1975)

Applied to rights of way, landscape, structures and non-agricultural areas, 45.3%; Grains, 41.3%; Forage crops vegetables and turf account for remainder applied (1984). /California use, calculated from table/

According to the EPA Pesticide Sales and Usage Report for 2000/2001, dicamba is the seventh most commonly used conventional pesticide in the home and garden market sector.

A total of 135,960 kg of dicamba was used on field crops, fruits and vegetables in Ontario, Canada in 1988

Dicamba is produced by hydrolysis of 1,2,4-trichlorobenzene with sodium hydroxide, followed by carboxylation, esterification with methanol, methylation of the hydroxyl group, and hydrolysis of the ester to the acid.

Preparation: S. B. Richter, United States of America patent 3013054 (1961 to Velsicol)

The National Pesticide Information Retrieval System (NPIRS) identifies 35 companies with active labels for products containing the chemical dicamba. To view the complete list of companies, product names and percent dicamba in formulated products click the following url and enter the CAS Registry number in the Active Ingredient field.

Dicamba Technical (Syngenta Crop Protection, LLC): Active ingredient: dicamba 92%.

Dicamba Technical 2 (Syngenta Crop Protection, LLC): Active ingredient: dicamba 98%.

Cool Power Selective Herbicide (Nufarm Americas, Inc.): Active ingredient: dicamba 3.6%; MCPA, 2-ethylhexyl ester 56.14%; and triclopyr, butoxyethyl ester 5%.

For more Formulations/Preparations (Complete) data for Dicamba (28 total), please visit the HSDB record page.

Environmental transformation -> Pesticides (parent, predecessor)

Herbicides

HERBICIDES

The WHO Recommended Classification of Pesticides by Hazard identifies Dicamba (technical grade) as Class II: moderately hazardous; Main Use: herbicide.

Used in combinations with many other herbicides. Dosage varies with specific use and ranges from 0.1 to 0.4 kg/ha for crop use, higher rates in pasture.