2,4-DB

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

Group II Containers: Non-combustible containers from organic or metallo-organic pesticides (except organic mercury, lead, cadmium, or arsenic compounds) must first be triple-rinsed. Containers that are in good condition may be returned to the manufacturer or formulator of the pesticide product, or to a drum reconditioner for reuse with the same type of pesticide product, if such reuse is legal under Department of Transportation regulations (eg 49 CFR 173.28). Containers that are not to be reused should be punctured ... and transported to a scrap metal facility for recycling, disposal or burial in a designated landfill. /Organic or metallo-organic pesticides/

Tolerances are established for the combined residues of the herbicide 4-(2,4-dichlorophenoxy)butyric acid and its metabolite 2,4-dichlorophenoxyacetic acid in or on the following raw agricultural commodities: Alfalfa: 0.2 ppm (negligible residues); Clover: 0.2 ppm (negligible residues); Mint, hay: 0.2 ppm; Peanuts: 0.2 ppm (negligible residues); Soybeans: 0.2 ppm (negligible residues); Soybeans, hay: 0.2 ppm (negligible residues); and Trefoil, birdsfoot: 0.2 ppm (negligible residues).

The general treatment of acute chlorophenoxy herbicide poisoning consists of decontamination of the gastrointestinal tract, resuscitation and supportive care. For severe, acute oral poisoning by 2,4-DB or 2,4-D, forced alkaline diuresis appears to be most effective (A7734). Forced alkaline diuresis is often used to increase the excretion of acidic drugs like salicylates and phenobarbitone. For forced alkaline diuresis, a diuretic like furosemide is given intravenously and sodium bicarbonate is added to the infusion fluid to make blood and, in turn, urine alkaline. Potassium replacement becomes of utmost importance during the process because potassium is usually lost in urine. If blood levels of potassium are depleted below normal levels, then hypokalemia occurs, which promotes bicarbonate ion retention and prevents bicarbonate excretion, thus interfering with the alkalinization of the urine.

All forms of 2,4-DB are considered low in toxicity when absorbed via skin or via inhalation. Female rats fed moderate doses of 75 mg/kg of 2,4-DB, experienced a number of chronic effects including lower ovarian weights, fewer offspring born and lower overall body weight. In addition, numerous offspring (pups) died during lactation.

TERRESTRIAL FATE: Microbial degradation is the major decomposition mechanism for phenoxyalkanoic acids (such as 4-(2,4-dichlorophenoxy)butyric acid) in soil(1-2). The microbial degradation occurs through a beta-oxidation mechanism to form (2,4-dichlorophenoxy)acetic acid (2,4-D)(2-3). In moist soils at 21 °C, the beta-oxidation half-life is about 3-4 days(3). In laboratory persistence studies using three different soil types (heavy clay, clay loam, sandy loam), half-lives of less than 7 days were observed(4). At normal herbicide application rates, 4-(2,4-dichlorophenoxy)butyric acid has a residual activity of about 6 weeks in soil(2). An experimentally measured Koc value of 370(5) suggests that 4-(2,4-dichlorophenoxy)butyric acid will be moderately mobile in soil and could therefore leach(SRC).

AQUATIC FATE: Microbial degradation is probably the major degradation process in the aquatic environment since it is the major decomposition mechanism for phenoxyalkanoic acids (such as 4-(2,4-dichlorophenoxy)butyric acid) in soil(1-2). The results of one aqueous stability study have also suggested that microbial degradation is important(3). Since 4-(2,4-dichlorophenoxy)butyric acid absorbs UV light in the environmental spectra(1), exposure to sunlight may contribute to its environmental decomposition; however, the relative importance of photolysis is unknown(SRC). Aquatic hydrolysis, bioconcentration and adsorption to sediment are not expected to be important fate processes(SRC).

ATMOSPHERIC FATE: Based upon an estimated vapor pressure of 3.5X10-6 mm Hg at 25 °C(1), 4-(2,4-dichlorophenoxy)butyric acid can exist in both the vapor and particulate-phases in the ambient atmosphere(2,SRC). It will degrade rapidly in the vapor-phase by reaction with photochemically produced hydroxyl radicals with an estimated half-life of 27 hr(3,SRC). Physical removal of particulates by dry deposition (settling) and wet deposition (rainfall, washout) will also occur(SRC).

As part of the Food and Drug Administration's Market Basket Survey of ready-to-eat foods, 4-(2,4-dichlorophenoxy)butyric acid was detected at a level of 0.025 ppm in a dairy product collected from a Los Angeles grocery store(1); 4-(2,4-dichlorophenoxy)butyric acid was classified as a pesticide that was infrequently found in American foods(1). In a compilation of three federal monitoring programs for fiscal years 1970-1976 (FDA's Market Basket Survey, FDA's Monitoring Program for 33,000 domestic and 18,000 raw agricultural commodities, and USDA's National Residue Program), 4-(2,4-dichlorophenoxy)butyric acid was detected in only one bean sample and in only one vine and ear vegetable sample(2).

Some of the endocrine effects of 2,4-DB may be mediated by the 2,4-D mediated displacement of sex hormones from the sex hormone binding globulin or the 2,4-D mediated blocking or OAT6 transport proteins that are needed for the transport of functional organic ions and dicarboxylates (including estrone sulfate).

Symptoms of acute oral exposure include vomiting, diarrhea, headache, confusion, renal failure, aggressive or bizarre behavior, hypotension and muscle twitching. Skeletal muscle injury and renal failure may also occur. Prolonged dermal exposure may include skin irritation, whereas prolonged inhalation exposure may lead to coughing and burning sensations in the upper respiratory tract and chest. (L177)

4-(2,4-Dichlorophenoxy)butyric acid (2,4-DB)

8 x 10 ^-3 mg/kg-day

Because dermal absorption is an important route of exposure to chlorophenoxy herbicides, biological monitoring is useful in estimating the absorbed dose. Urine concn provide the most accurate estimate of body burden; because of slow absorption, it is best to collect samples after a few days of exposure. /Chlorophenoxy herbicides/

Tolerances are established for the combined residues of the herbicide 4-(2,4-dichlorophenoxy)butyric acid and its metabolite 2,4-dichlorophenoxyacetic acid in or on the following raw agricultural commodities: alfalfa, clover, mint, peanuts, soybeans, and trefoil.

Used as selective post-emergence herbicide for control of annual and perennial broad leave weeds in clovers, cereals, grassland, legumes, and groundnuts; [HSDB] Used to control broadleaf weeds in alfalfa, clover, peanuts, soybeans, peppermint, spearmint, and birdsfoot trefoil; [Reference #1]

Farming (Pesticides) [Category: Industry]

Control of broad-leafed plants in row crops; defoliants, general brush control. /Chlorophenoxy compounds; from table/

Post-emergence control of many annual and perennial broad-leafed weeds in lucerne, clovers, undersown cereals, grassland, forage legumes, soya-beans, and groundnuts.

Selective, translocated hormone-type herbicide

Broadleaf herbicide, widely used in agriculture, functions as a synthetic auxin. (L177, L178)

Chlorophenoxy ester herbicides can ... be produced by direct reaction of chlorophenol with appropriate chloroacetic esters ... . /Chlorophenoxy herbicides/

React 2,4-dichlorophenol with trimethylene chlorobromide. Then react the product (3-(2,4-dichlorophenoxy)propyl-chloride), with sodium cyanide, saponify, acidify. The resultant compound is 2,4-dichlorophenoxybutyric acid.

Herbicides

HERBICIDES

Chlorophenoxy herbicides are applied alone or as mixtures with other herbicides, in solutions, dispersions, or emulsions in water &/or oil, using equipment that produces large droplets to avoid spray drift. /Chlorophenoxy herbicides/

New Zealand: The spraying of phenoxyherbicides is restricted within prescribed distances of vineyards. /Phenoxyherbicides/