2,6-Dichlorobenzamide

Environmental transformation -> Pesticide transformation products (metabolite, successor)

Pesticides -> Herbicides -> Nitrile herbicides -> Transformation products

Pesticide (2,6-dichlorobenzamide) -> USDA PDB

Pesticide degradation product

Chemical: Benzamide, 2,6-dichloro-

Commission Regulation (EC) No 1490/2002

2,6-Dichlorobenzamide (BAM) is listed in the dataset of EPA Human Health Benchmarks for Pesticides under the Safe Drinking Water Act (40 eCFR 141)

USEPA/Office of Prevention, Pesticides and Toxic Substances; Reregistration Eligibility Decision Document for Dichlobenil EPA 738-R-98-003 (October 1998). 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. /The BAM metabolite of dichlobenil is the major residue detected in plants./[Available from, as of October 26, 2017: http://www.epa.gov/pesticides/reregistration/status.htm]

Tolerances are established for the combined residues of the herbicide dichlobenil (2,6-dichlorobenzonitrile) and its metabolite 2,6-dichlorobenzamide in or on the following raw agricultural commodities:[Table#4159]

Based on the reviews of the generic data for the active ingredients dichlobenil, the Agency has sufficient information on the health effects of dichlobenil and on its potential for causing adverse effects in fish and wildlife and the environment. The Agency has determined that dichlobenil products, labeled and used as specified in this Reregistration Eligibility Decision, will not pose unreasonable risks or adverse effects to humans or the environment with the exception of sewer and granular backpack application use sites. Therefore, the Agency concludes that products containing dichlobenil for the remaining uses are eligible for reregistration under the conditions specified in this RED.

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

Advice for firefighters: Wear self-contained breathing apparatus for firefighting if necessary.

ACCIDENTAL RELEASE MEASURES: Personal precautions, protective equipment and emergency procedures: Avoid dust formation. Avoid breathing vapors, mist or gas. Environmental precautions: Do not let product enter drains. Methods and materials for containment and cleaning up: Sweep up and shovel. Keep in suitable, closed containers for disposal.

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.

Product: Offer surplus and non-recyclable solutions to a licensed disposal company; Contaminated packaging: Dispose of as unused product.

ACCIDENTAL RELEASE MEASURES: Personal precautions, protective equipment and emergency procedures: Avoid dust formation. Avoid breathing vapors, mist or gas. Environmental precautions: Do not let product enter drains.

Precautions for safe handling: Provide appropriate exhaust ventilation at places where dust is formed. Normal measures for preventive fire protection.

Appropriate engineering controls: General industrial hygiene practice.

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.

SRP: Local exhaust ventilation should be applied wherever there is an incidence of point source emissions or dispersion of regulated contaminants in the work area. Ventilation control of the contaminant as close to its point of generation is both the most economical and safest method to minimize personnel exposure to airborne contaminants. Ensure that the local ventilation moves the contaminant away from the worker.

Eye/face protection: Use equipment for eye protection tested and approved under appropriate government standards such as NIOSH (US) or EN 166(EU).

Skin protection: Handle with gloves.

Body Protection: Choose body protection in relation to its type, to the concentration and amount of dangerous substances, and to the specific work-place.

Respiratory protection: Respiratory protection is not required. Where protection from nuisance levels of dusts are desired, use type N95 (US) or type P1 (EN 143) dust masks. Use respirators and components tested and approved under appropriate government standards such as NIOSH (US) or CEN (EU).

EC50; Species: Chlorella pyrenoidosa (Green Algae); Conditions: freshwater, static, pH 8.7, hardness 90 mg/L CaCO3; Concentration: 100000 ug/L for 96 hr; Effect: biochemistry, chlorophyll /97% purity/

LC50; Species: Daphnia magna (Water Flea); Conditions: freshwater, static, pH 8.1, hardness 260 mg/L CaCO3; Concentration: 856000 ug/L for 48 hr (95% confidence interval: (725000-1010000 ug/L) /97% purity/

LC50; Species: Daphnia magna (Water Flea); Conditions: freshwater, renewal, 20 °C, pH 8.1, hardness 225 mg/L CaCO3; Concentration: 320000 ug/L for 21 days /97% purity/

LC50; Species: Poecilia reticulata (Guppy); Conditions: freshwater, static, pH 8.1, hardness 260 mg/L CaCO3; Concentration: 275000 ug/L for 96 hr (95% confidence interval: 180000-560000 ug/L) /97% purity/

For more Ecotoxicity Values (Complete) data for 2,6-Dichlorobenzamide (6 total), please visit the HSDB record page.

TERRESTRIAL FATE: Based on a classification scheme(1), a measured Koc value of 30 on activated sludge(2) indicates that 2,6-dichlorobenzamide is expected to have very high mobility in soil(SRC). Volatilization of 2,6-dichlorobenzamide from moist soil surfaces is not expected to be an important fate process(SRC) given an estimated Henry's Law constant of 1.2X10-9 atm-cu m/mole(SRC), using a fragment constant estimation method(3). 2,6-Dichlorobenzamide is not expected to volatilize from dry soil surfaces(SRC) based upon an estimated vapor pressure of 4.8X10-6 mm Hg at 25 °C(SRC), determined from a fragment constant method(3). Using a soil grab sample, 0.4-6.1% of 2,6-dichlorobenzamide degraded after 4-110 days of incubation(4), indicating that 2,6-dichlorobenzamide does not biodegrade rapidly in soil(SRC).

AQUATIC FATE: Based on a classification scheme(1), a measured Koc value of 30 on activated sludge(2) indicates that 2,6-dichlorobenzamide is not expected to adsorb to suspended solids and sediment(SRC). Volatilization from water surfaces is not expected(3) based upon an estimated Henry's Law constant of 1.2X10-9 atm-cu m/mole(SRC), developed using a fragment constant estimation method(4). According to a classification scheme(5), a measured BCF of 10 in Golden Ide fish(2), suggests the potential for bioconcentration in aquatic organisms is low(SRC). 2,6-Dichlorobenzamide reached 5.6% mineralization after 40 days in pond water(6), indicating that 2,6-dichlorobenzamide does not biodegrade rapidly in water(SRC).

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), 2,6-dichlorobenzamide, which has an estimated vapor pressure of 4.8X10-6 mm Hg at 25 °C(SRC), determined from a fragment constant method(2), will exist in both the vapor and particulate phases in the ambient atmosphere. Vapor-phase 2,6-dichlorobenzamide 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 5.6 days(SRC), calculated from its rate constant of 2.9X10-12 cu cm/molecule-sec at 25 °C(SRC) that was derived using a structure estimation method(3). Particulate-phase 2,6-dichlorobenzamide may be removed from the air by wet and dry deposition(SRC). 2,6-Dichlorobenzamide does not contain chromophores that absorb at wavelengths >290 nm(4) and, therefore, is not expected to be susceptible to direct photolysis by sunlight(SRC).

IDENTIFICATION AND USE: 2,6-Dichlorobenzamide (BAM) was formerly used as a pesticide. HUMAN STUDIES: There are no data available. ANIMAL STUDIES: BAM was given to rats (35/sex/dose) for 106 weeks at doses 0, 2.2, 3.6, 6.5, or 19 mg/kg/day in males; 0, 2.8, 4.7, 8.5, or 25 mg/kg/day in females. There was a statistically significant decrease in mean body weight gains in both males and females (10% and 20% less than controls, respectively, at week 52), and slightly increased severity of fat deposition in the livers of females. BAM produced an increased incidence of hepatoma in females. The carcinogenic potential of BAM appears to be less than or equal to that of dichlobenil. In a single dose study in which the group of mice was treated at 250 mg/kg, the mice displayed mild neurotoxic effects (lethargy and ataxia), the group treated at 500 mg/kg were severely affected (becoming comatose), and the groups treated at 1000 mg/kg and higher died in extremis. A mouse micronucleus assay using a single dose of BAM (250 mg/kg) was negative. BAM was negative for inducing repair of DNA damage as measured by unscheduled DNA synthesis (UDS), as determined by net nuclear silver grain count in primary rat hepatocytes, exposed up to cytotoxic doses (1000 ug/mL). BAM was negative for inducing reverse gene mutation in TA strains of Salmonella typhimurium with and without metabolic activation. ECOTOXICITY STUDIES: Short term experiments showed that BAM was moderately toxic to guppies Poecilia reticulata, rainbow trout Salmo gairdneri, daphnids Daphnia magna and the algae Chlorella pyrenoidosa and Scenedesmus pannonicus. In long term studies with daphnids concentrations up to 320 mg/L did not significantly alter survival and reproduction. An embryolarval test with rainbow trout, however, showed a significant reduction of survival and growth as well as a delay of yolk resorption at concentrations equal to or exceeding 18 mg/L. The accumulation of unchanged BAM in leaf tips and margins was reported to be the cause of leaf margin chlorosis.

/AQUATIC SPECIES/ Dichlobenil (2,6-dichlorobenzonitrile) is a broad-spectrum herbicide of which the aquatic toxicological properties are well documented compared to the scarcity of data on the toxicity of its main degradation product BAM (2,6-dichlorobenzamide). Therefore toxicity tests with BAM were carried out with several freshwater species. Short term experiments showed that BAM was moderately toxic to guppies Poecilia reticulata, rainbow trout Salmo gairdneri, daphnids Daphnia magna and the algae Chlorella pyrenoidosa and Scenedesmus pannonicus. In long term studies with daphnids concentrations up to 320 mg/L did not significantly alter survival and reproduction. An embryolarval test with rainbow trout, however, showed a significant reduction of survival and growth as well as a delay of yolk resorption at concentrations equal to or exceeding 18 mg/L. In combination with the data reported in the literature it may be concluded that degradation of dichlobenil into BAM results in a reduction of toxicity and further biodegradability. Normal field applications of this aquatic herbicide are not expected to impose a great risk to aquatic life.

/PLANTS/ The accumulation of unchanged 2,6-dichlorobenzamide in leaf tips and margins was reported to be the cause of leaf margin chlorosis ... .

A commercial apple orchard of Idared on Malling 7 rootstack was treated with dichlobenil at the maximum recommended rate (8.97 kg/ha) in 1974, 1976, and 1978. Residues of dichlobenil and the metabolite 2,6-dichlorobenzamide were determined in leaves, fruit, and soil. 2,6-Dichlorobenzamide was present in higher amounts in the leave and soil samples compared to dichlobenil. Small amounts of 2,6-dichlorobenzamide were also detected in fruit. The residue levels were higher and foliar phytotoxicity symptoms, characterized by leaf margin yellowing and leaf tip burn, were more marked in fruiting tress(1).

EPA has released the Interactive Chemical Safety for Sustainability (iCSS) Dashboard. The iCSS Dashboard provides an interactive tool to explore rapid, automated (or in vitro high-throughput) chemical screening data generated by the Toxicity Forecaster (ToxCast) project and the federal Toxicity Testing in the 21st century (Tox21) collaboration. /The title compound was tested by ToxCast and/or Tox21 assays/[USEPA; ICSS Dashboard Application; Available from, as of November 16, 2017: http://actor.epa.gov/dashboard/]

2,6-Dichlorobenzamide was not detected in the biodegradable fraction of household waste collected in 1995, or its 5-month compost; it was detected at trace quantities in all samples of anaerobic mesophilic digestates after 30 days and anaerobic thermophilic digestates after 19 days(1).

The Koc of 2,6-dichlorobenzamide measured on activated sludge is reported to be 30(SRC). According to a classification scheme(2), this Koc value suggests that 2,6-dichlorobenzamide is expected to have very high mobility in soil(SRC).

2,6-Dichlorobenzamide, was detected, at a concentration of 28% of applied dichlobenil in the 25-30 cm segment of the column, after aerobic ageing of dichlobenil on a treated silt loam soil column(1). In a field study, an established commercial orchard in the Town of Huron, NY, was treated with dichlobenil at 6 lb ai/acre; the degradate 2,6-dichlorobenzamide was detected to a depth of 72 inches (max sampling depth)(1). More dichlobenil was converted to the water-soluble 2,6-dichlorobenzamide in loam soil than in sandy soil. This water-soluble metabolite was partially leached through the loam soil column with the highest level of irrigation(2). These data suggest 2,6-dichlorobenzamide has the potential to leach into groundwater through soil(1).

2,6-Dichlorobenzamide is the degradation product and major terminal residue in plants of dichlobenil(1,2), and may be indirectly released into the environment after the herbicidal use and transformation of dichlobenil(SRC). Its former use in the manufacture of dichlobenil(3) may have resulted in its release to the environment through various waste streams(SRC).

AEROBIC: 2,6-Dichlorobenzamide, present at 100 mg/L, reached 0%, 0.5%, 1.25%, 2.25%, 3.25%, 3.5%, and 5% degradation in 0, 25, 75, 105, 155, 180, and 300 days, respectively, using a grab soil inoculum(1). Using an organic rich soil (mixed with 50% sand) grab inoculum, 2,6-dichlorobenzamide, present at 400 mg/L, reached 0%, 3%, 6%, and 10% degradation after 0, 13, 46, and 206 days, respectively(1). 0%, 6%, and 16% of 2,6-dichlorobenzamide (initial concn = 400 mg/l) degraded after 0, 13, 205 days, respectively, using a grab sample of clay soil mixed with 50% sand(1). Using a clay-lime soil grab sample, 0.4%, 0.9%, 3%, and 6.1% of 2,6-dichlorobenzamide (initial concentration = 1 mg/L) degraded after 4, 12, 51, and 110 days of incubation, respectively(2). 2,6-Dichlorobenzamide was not degraded in unamended batch and column experiments assessing aquifer degradation under aerobic conditions(3). 2,6-Dichlorobenzamide reached 5.6% mineralization after 40 days in pond water(4); in aquifer sediments 2,6-dichlorobenzamide has an estimated half-life of 3-16 years(4). These data suggest that 2,6-dichlorobenzamide does not biodegrade rapidly in the environment(SRC).

AEROBIC: Studies on the fate of dichlobenil in soils have shown that 2,6-dichlorobenzamide is the major degradation product(1,2). The major degradation products of chlorthiamid are dichlobenil and 2,6-dichlorobenzamide(1). 2,6-Dichlorobenzamide is the second major chlorthiamid degradation product in soils(1). Degradation studies with [(14)C]-2,6-dichlorobenzamide have shown that this major metabolite of dichlobenil is resistant to further breakdown in soil samples stored for six months(1). 2,6-Dichlorobenzamide was rapidly mineralized in soils previously exposed to dichlobenil, with complete mineralization after 35-56 days(2); however, it was not degraded further in soils not previously treated with dichlobenil(2). In soils previously treated with dichlobenil, complete mineralization of 2,6-dichlorobenzamide to CO2 was attributed to the bacterial strain Aminobactor sp. ASI1(1); mineralization was detected in samples from six locations in which 2,6-dichlorobenzamide reached 5.2-64.6% mineralization within 48-50 days; rapid mineralization was evident at 2 m below the surface(3). These data suggest that 2,6-dichlorobenzamide is the end product of dichlobenil in soils not previously treated with dichlobenil(1,2).

... We examined whether peat, compost-peat-sand (CPS) mixture, NH4NO3, NH4NO3 with sodium citrate (Na-citrate), and the surfactant methyl-beta-cyclodextrin additions enhance atrazine, simazine, hexazinone, dichlobenil, and the degradate 2,6-dichlorobenzamide (BAM) dissipations in sediment slurries under aerobic and anaerobic conditions, with sterilized controls. The vadose zone sediment cores were drilled from a depth of 11.3-14.6m in an herbicide-contaminated groundwater area. The peat and CPS enhanced chemical atrazine and simazine dissipation, and the peat enhanced chemical hexazinone dissipation, all oxygen-independently. Dichlobenil dissipated under all conditions, while BAM dissipation was fairly slow and half-lives could not be calculated. The chemical dissipation rates could be associated with the chemical structures and properties of the herbicides, and additive compositions, not with pH. ...

PURE CULTURE: Aminobacter sp. MSH1 immobilized in an alginate matrix in porous stones was tested in a pilot system as an alternative inoculation strategy to the use of free suspended cells for biological removal of micropollutant concentrations of 2,6-dichlorobenzamide (BAM) in drinking water treatment plants (DWTPs). BAM removal rates and MSH1 cell numbers were recorded during operation and assessed with specific BAM degradation rates obtained in lab conditions using either freshly grown cells or starved cells to explain reactor performance. Both reactors inoculated with either suspended or immobilized cells showed immediate BAM removal under the threshold of 0.1 ug/L, but the duration of sufficient BAM removal was 2-fold (44 days) longer for immobilized cells. ... Overall loss of activity in the reactors though was due to starvation, and final removal rates did not differ between reactors inoculated with immobilized and suspended cells. Management of assimilable organic carbon, in addition to cell immobilization, appears crucial for guaranteeing long-term BAM degradation activity of MSH1 in DWTP units.

ANAEROBIC: 2,6-Dichlorobenzamide is extremely persistent under anaerobic conditions(1). 2,6-Dichlorobenzamide was not degraded in degradation experiments assessing aquifer degradation under anaerobic conditions(2).

A BCF of 10 was measured for Golden Ide fish after a 3 day equilibration period(1). According to a classification scheme(2), this BCF suggests the potential for bioconcentration in aquatic organisms is low(SRC). The BCF for algae ranges from <10 to 320 after a 1 day equilibration period(1,3).

The Henry's Law constant for 2,6-dichlorobenzamide is estimated as 1.2X10-9 atm-cu m/mole(SRC) using a fragment constant estimation method(1). This Henry's Law constant indicates that 2,6-dichlorobenzamide is expected to be essentially nonvolatile from water surfaces(2). 2,6-Dichlorobenzamide's Henry's Law constant indicates that volatilization from moist soil surfaces will not likely occur(SRC). 2,6-Dichlorobenzamide is not expected to volatilize from dry soil surfaces(SRC) based upon an estimated vapor pressure of 4.8X10-6 mm Hg at 25 °C(SRC), determined from a fragment constant method(3). Using a screening test, 0.5% of applied 2,6-dichlorobenzamide volatilized from sludge(4).

Tolerances are established for the combined residues of the herbicide dichlobenil (2,6-dichlorobenzonitrile) and its metabolite 2,6-dichlorobenzamide in or on the following raw agricultural commodities:[Table#4159]

Based on the reviews of the generic data for the active ingredients dichlobenil, the Agency has sufficient information on the health effects of dichlobenil and on its potential for causing adverse effects in fish and wildlife and the environment. The Agency has determined that dichlobenil products, labeled and used as specified in this Reregistration Eligibility Decision, will not pose unreasonable risks or adverse effects to humans or the environment with the exception of sewer and granular backpack application use sites. Therefore, the Agency concludes that products containing dichlobenil for the remaining uses are eligible for reregistration under the conditions specified in this RED.

... Both free and conjugated 3-hydroxy-2,6-dichlorobenzamide were ... isolated as metabolites from apple ... leaves treated directly with 2,6-dichlorobenzamide. Free and conjugated 3-hydroxy-2,6-dichlorobenzamide have been detected chromatographically in wheat seedlings and kale (Brassica oleracea) plants after short-term (1-5 days) root and soil uptake studies with [(14)C]2,6-dichlorobenzamide.

Long-term soil uptake studies (14 weeks) with [(14)C]2,6-dichlorobenzamide showed that the major metabolites in leaves of young apple trees were 3- and 4-hydroxy-2,6-dichlorobenzamide in a ratio of 6:1. Approx 85% of the hydroxylated metabolites were conjugated as glycosides. ... It appears that plants are able to hydroxylate and conjugate ... 2,6-dichlorobenzamide and that hydroxylation at the 3 position ... is favored. A comparison of dichlobenil and 2,6-dichlorobenzamide metabolism after 5 days in root treated bean seedlings showed that 2,6-dichlorobenzamide was hydroxylated and conjugated much slower than dichlobenil.

2,6-Dichlorobenzamide is metabolized to 2,6-dichlorobenzoic acid probably in phaseolus. /From table/

/In foliar and roots/ ... 2,6-dichlorobenzamide is readily absorbed and translocated in xylem with the transpiration stream /and/ ... accumulates ... in foliar tissues. Autoradiograms of apple leaves from seedlings and young trees show that translocated [(14)C]2,6-dichlorobenzamide is distributed throughout the leaf and tends to accumulate at the leaf margins after prolonged periods of root uptake.

Used in the synthesis of dichlobenil; [HSDB]

For 2,6-dichlorobenzamide (USEPA/OPP Pesticide Code: 027402) there are 0 labels match. /SRP: Not registered for current 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./

/Formerly/ in synthesis of dichlobenil

Environmental transformation -> Pesticide transformation products (metabolite, successor)

Transformation products

Pesticides -> Herbicides -> Nitrile herbicides -> Transformation products