Chlorfenac (ISO)

LC50 BOBWHITE QUAIL, 14 DAY OLD, ORAL GREATER THAN 5000 PPM (NO MORTALITY TO 5000 PPM)

LC50 JAPANESE QUAIL, 14 DAY OLD, ORAL GREATER THAN 5000 PPM (NO MORTALITY TO 5000 PPM)

LC50 RING-NECKED PHEASANTS, 10 DAY OLD, ORAL GREATER THAN 5000 PPM (NO MORTALITY TO 5000 PPM)

LC50 MALLARD DUCKS, 10 DAY OLD, ORAL GREATER THAN 5000 PPM (NO MORTALITY TO 5000 PPM)

For more Ecotoxicity Values (Complete) data for 2,3,6-TRICHLOROPHENYLACETIC ACID (11 total), please visit the HSDB record page.

TERRESTRIAL FATE: OVER A 3 YR PERIOD, HIGHEST CONCN IN LOSS FROM RUNOFF WERE USUALLY ASSOCIATED WITH RAINSTORMS THAT OCCURRED SOON AFTER APPLICATION. MAXIMAL SEASONAL LOSSES WERE 2.90% OF THE APPLIED FENAC

TERRESTRIAL FATE: ... RESISTS DECOMPOSITION IN SOIL MUCH LONGER THAN ... /CHLOROPHENOXACETIC ACIDS/.

TERRESTRIAL FATE: If released to soil, estimated soil adsorption coefficients ranging from 237 to 1311(1) indicate low to moderate mobility for 2,3,6-trichlorophenylacetic acid(SRC) based on a suggested classification scheme(2). Due to its high degree of ionization at environmental pHs, percent organic matter, clay content, and soil pH are also important factors in determining its degree of adsorption(3). An estimated vapor pressure for 2,3,6-trichlorophenylacetic acid of 1.7x10-5 mm Hg at 25 °C(4) and estimated Henry's Law constant of 1.8x10-8 atm-cu m/mole at 25 °C(5) indicate that important. Biodegradation of 2,3,6-trichlorophenylacetic acid in soil under both aerobic and anaerobic conditions is slow based on data from both laboratory(6) and field experiments(7) although it may be subject to enhanced degradation through cometabolic processes(8).

AQUATIC FATE: If released to water, 2,3,6-trichlorophenylacetic acid is expected to persist for long periods of time. No degradation of 2,3,6-trichlorophenylacetic acid was observed when it was incubated with lake water/sediment or activated sludge under aerobic conditions or when incubated with a sandy loam soil in water under anaerobic conditions(1). Biodegradation studies with soil inoculum and added nutrients produced an enhanced removal rate(1) suggesting that cometabolic process may be important(2). Adsorption of 2,3,6-trichlorophenylacetic acid to sediment may be important based on estimated soil adsorption coefficients ranging from 237 to 1311(3) determined from its water solubility, 200 mg/L(4), and octanol/water partition coefficient, 3.20(5). Laboratory studies have indicated rapid adsorption to sediment(1) although pH, percent organic matter, and clay content of sediment may also be important in determining the degree of adsorption due to 2,3,6-trichlorophenylacetic acid's high degress of ionization at environmental pHs(6-7).

For more Environmental Fate (Complete) data for 2,3,6-TRICHLOROPHENYLACETIC ACID (6 total), please visit the HSDB record page.

Experimental soil adsorption coefficients ranging from 0.3 to 667 on four different sediments with percent organic carbon ranging from 0.3 to 54 were observed at pH 6.5; adsorption on organic muck was found to increase at pH 4.5 but not at pH 9(1). Soil pH, especially in the range 5.0-6.7, was described as the most important factor in 2,3,6-trichlorophenylacetic acid mobility(2-3). At neutral or basic pHs, 2,3,6-trichlorophenylacetic acid will exist predominately as the ionized acid and adsorption to soil will driven by ionic interactions between it and the soil while at more acidic pHs hydrophobic processes will predominate(4). Soil TLC experiments using a wide range of soils (Hagerstown silty clay loam, Lakeland sandy loam, Chillium silt loam) produced Rfs ranging from 0.38 to 1.0 indicating that 2,3,6-trichlorophenylacetic acid has a high degree of mobility compared to other pesticides(2-6).

Based on an experimental log Kow of 3.20 for 2,3,6-trichlorophenylacetic acid, obtained in 0.1 and 0.5 M HCl(1), and its water solubility, 280 mg/L at 28 °C(2), estimated soil adsorption coefficients ranging from 159 to 1311 can be calculated using an appropriate regression equation(3). According to a suggested classification scheme(4), these values suggest that 2,3,6-trichlorophenylacetic acid will display moderate to high mobility in soil. A Koc of 170 has been estimated for 2,3,6-trichlorophenylacetic acid based on its heat of solution(5). In a scale on mobility of pesticides in soil ranging from 1, immobile, to 5, highly mobile, 2,3,6-trichlorophenylacetic acid was placed in mobility class 4(6).

SYMPTOMATOLOGY (PARTLY INFERENTIAL): 1. FATIGUE, WEAKNESS, ANOREXIA; PERHAPS NAUSEA, VOMITING & DIARRHEA. 2. HYPOREFLEXIA & LETHARGY PROGRESSING TO COMA, WITH CONSTRICTED PUPILS (MIOSIS). 3. FLACCID PARALYSIS HAS BEEN DESCRIBED IN ONE COMATOSE PT & GRAND MAL CONVULSIONS WITH OPISTHOTONOS IN ANOTHER, HYPERTONIA WITH AREFLEXIA IN A THIRD, & TWITCHING & JERKING IN A FOURTH. ... 5. PROGRESSIVE DECLINE IN BLOOD PRESSURE WITH DEATH IN DEEP COMA. THE POSSIBILITY THAT HYPERPYREXIA & HYPERMETABOLISM MAY HAVE CONTRIBUTED TO THE FATAL OUTCOME DOES NOT APPEAR TO HAVE BEEN RULED OUT (ONE COMATOSE PATIENT WAS DESCRIBED AS SWEATING PROFUSELY). A TERMINAL PNEUMONIA IS LIKELY. 6. DISTURBANCES IN BODY TEMP REGULATION MAY BE ENCOUNTERED. PERHAPS SEVERE REDUCTION OF BODY TEMP IN COOL OR COLD ENVIRONMENTS. MORE PROBABLY, FEBRILE RESPONSES IN WARM ENVIRONMENTS OR DURING EXERCISE. 7. PROGRESSIVE HYPOTENSION WITH DEATH IN PERIPHERAL VASCULAR COLLAPSE, PERHAPS ASSOCIATED WITH ACIDOSIS DUE TO LACTIC ACIDEMIA & OTHER PRODUCTS OF HYPERMETABOLISM. 8. IN NONFATAL POISONINGS, SEVERE & PROTRACTED ... /PRC: NEUROPATHY/ WITH PAIN, PARESTHESIAS & WEAKNESS. ... HUMANS HAVE EXPERIENCED MUSCLE FASCICULATIONS AS WELL AS MYOTONIA. CHRONIC EXPOSURE MAY LEAD TO CENTRAL NERVOUS SYSTEM DEFECTS IN THE CONTROL OF MOTOR FUNCTION. /2,4-D/

2,3,6-Trichlorophenylacetic acid was used as both a pre- and post-emergence herbicide to control annual grasses, broad-leaved weeds(1) and to control submerged aquatic weeds(2). Use of 2,3,6-trichlorophenylacetic acid as a herbicide results in direct application to the environment and is, therefore, its primary environmental emission source(SRC).

No degradation of 2,3,6-trichlorophenylacetic acid was observed when incubated with lake water/sediment or activated sludge under aerobic conditions or with a sandy loam soil in water under anaerobic conditions(1). More than 75% of 2,3,6-trichlorophenylacetic acid remained after 120 day biodegradation studies in lake water (Oneida Lake, NY), primary sewage effluent, soil, and soil/water suspensions; adding supplemental nutrients deceases the amount remaining to 40% after 120 days in soil inoculum while little effect was observed using other media. Cometabolic degradation may be the major biodegradation process for 2,3,6-trichlorophenylacetic acid in aquatic systems(2). A dichlorohydroxybenzene derivative was tentatively identified as a product of the biodegradation of 2,3,6-trichlorophenylacetic acid in soil(2). 2,3,6-Trichlorophenylacetic acid was described as being susceptible to decarboxylation reactions when incubated with soil inoculum(3).

Two years after soil application of 2,3,6-trichlorophenylacetic acid, crop injury was observed and used to describe its presence and thus resistance to biodegradation in soil(1-2). A field study at 6 different soil type locations indicated that 2,3,6-trichlorophenylacetic acid was persistent in soil as residues remained 18 months after spraying(2). Residues of 2,3,6-trichlorophenylacetic acid in water and sediment samples of 0.38 ppm and 0.26 ppm, respectively, were found 160 days after an initial application of 1.56 ppm to a pond(3).

Experimental bioconcentration factors ranging from 1.6 to 11.6 in bluegills (Lepomis macrochirus) were determined in static tests with a 2,3,6-trichlorophenylacetic acid concentration of 2 ppm(1). Based on an experimental log Kow of 3.20 for 2,3,6-trichlorophenylacetic acid, obtained in 0.1 and 0.5 M HCl(2), and its water solubility, 200 mg/L at 28 °C(3), estimated bioconcentration factors ranging from 31 to 159 can be calculated(SRC) using an appropriate regression equation(4). The magnitude of these values indicate that bioconcentration in fish and aquatic organisms will not be a significant process(SRC).

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 future use. Under this pesticide reregistration program, EPA examines health and safety data for pesticide active ingredients initially registered before November 1, 1984, and determines whether they are eligible for reregistration. In addition, all pesticides must meet the new safety standard of the Food Quality Protection Act of 1996. Pesticides for which EPA had not issued Registration Standards prior to the effective date of FIFRA, as amended in 1988, were divided into three lists based upon their potential for human exposure and other factors, with List B containing pesticides of greater concern and List D pesticides of less concern. Trichlorophenylacetic acid is found on List D. Case No: 4020; Case Status: No products containing the pesticide are actively registered ... The case /is characterized/ as "cancelled." Under FIFRA, pesticide producers may voluntarily cancel their registered products. EPA also may cancel pesticide registrations if registrants fail to pay required fees or make/meet certain reregistration commitments, or if EPA reaches findings of unreasonable adverse effects.; Active ingredient (AI): Trichlorophenylacetic acid; AI Status: The active ingredient is no longer contained in any registered pesticide products ... "cancelled."

A tolerance is established for negligible residues of the herbicide 2,3,6-trichlorophenylacetic acid in or on sugarcane, such residues resulting from application of its dimethylamine or sodium salts.