2-tert-Butyl-4-methylphenol

TERRESTRIAL FATE: Based on a recommended classification scheme(1), an estimated Koc value of 3200(SRC), determined from a structure estimation method(2), indicates that 2-t-butyl-4-methylphenol will have no mobility in soil(SRC). Volatilization of 2-t-butyl-4-methylphenol may be important from moist soil surfaces(SRC) given an estimated Henry's Law constant of 1.5X10-6 atm-cu m/mole(3,SRC). Insufficient data are available to determine the rate or importance of biodegradation of 2-t-butyl-4-methylphenol in soil(SRC).

AQUATIC FATE: Based on a recommended classification scheme(1), an estimated Koc value of 3200(SRC), determined from a structure estimation method(2), indicates that 2-t-butyl-4-methylphenol may adsorb to suspended solids and sediment(SRC) in the water. 2-t-Butyl-4-methylphenol may volatilize from water surfaces based on an estimated Henry's Law constant of 1.5X10-6 atm-cu m/mole(SRC), developed using a fragment constant estimation method(3). Estimated half-lives for a model river and model lake are 31 and 227 days, respectively(4,SRC). An estimated BCF value of 610(4,SRC), from an estimated log Kow(5,SRC), suggests that 2-t-butyl-4-methylphenol will bioconcentrate in aquatic organisms(SRC) according to a recommended classification scheme(6). Insufficient data are available to determine the rate or importance of biodegradation of 2-t-butyl-4-methylphenol in water(SRC).

ATMOSPHERIC FATE: According to a suggested classification scheme(1), an extrapolated vapor pressure of 0.025 mm Hg at 25 °C(2,SRC) indicates that 2-t-butyl-4-methylphenol will exist primarily in the vapor phase in the ambient atmosphere. Vapor-phase 2-t-butyl-4-methylphenol 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 about 7.7 hours(3,SRC). Particulate-phase 2-t-butyl-4-methylphenol may be physically removed from the air by wet and dry deposition(SRC). Reaction of phenols with nitrate radicals may also be an important process(4,SRC).

Using a structure estimation method based on molecular connectivity indexes(1), the Koc for 2-t-butyl-4-methylphenol can be estimated to be about 3200(SRC). According to a recommended classification scheme(2), this estimated Koc value suggests that 2-t-butyl-4-methylphenol will be immobile in soil(SRC).

2-(Tert-butyl)-4-methylphenol (CAS # 2409-55-4) was evaluated for acute toxicity. The test was carried out for 96 hours with 5 Bluegills (Lepomis macrochirus) per concentration. Concentrations and mortality data at 96 hours are as follows: 50% (5/5); 25% (5/5); 15% (5/5); 10% (5/5); 5% (0/5); and control (0/5). The fish showed no signs of stress during the course of the test. Based on solubility an LC50 could not be defined.

An estimated BCF value of 610 was calculated for 2-t-butyl-4-methylphenol(SRC), using an estimated log Kow of 3.97(1,SRC) and a recommended regression-derived equation(2). According to aclassification scheme(3), this BCF value suggests that bioconcentration of 2-t-butyl-4-methylphenol will be high in aquatic organisms(SRC).

The Henry's Law constant for 2-t-butyl-4-methylphenol is estimated as 1.5X10-6 atm-cu m/mole(SRC) using a fragment constant estimation method(1). This value indicates that 2-t-butyl-4-methylphenol will volatilize from water surfaces(2,SRC). Based on this Henry's Law constant, the volatilization half-life from a model river (1 m deep, flowing 1 m/sec, wind velocity of 3 m/sec) is estimated as approximately 31 days(2,SRC). The volatilization half-life from a model lake (1 m deep, flowing 0.05 m/sec, wind velocity of 0.5 m/sec) is estimated as approximately 227 days(2,SRC). 2-t-Butyl-4-methylphenol's Henry's Law constant(1,SRC) indicates that volatilization from moist soil may occur(SRC).

IN MICE, A SINGLE IP DOSE OF 2-T-BUTYL-4-METHYLPHENOL CAUSED INCREASED WET & DRY LUNG WT. COMPARISON OF TESTED ALKYLPHENOL CMPD SHOWED THAT THE STRUCTURAL FEATURE ESSENTIAL FOR TOXIC ACTIVITY WAS A PHENOLIC RING HAVING A METHYL GROUP AT THE 4-POSITION & ORTHO-ALKYL GROUP(S) WHICH CAN RESULT IN A MODERATE HINDERING EFFECT ON THE HYDROXYL GROUP. THESE STRUCTURAL REQUIREMENTS SUPPORT THE HYPOTHESIS THAT QUINONE METHIDES OR CLOSELY RELATED METABOLITES WHICH ARE FORMED BY MICROSOMAL OXIDATION OF THE TOXIC PHENOLS PLAY A ROLE IN PRODUCING LUNG DAMAGE.

FEMALE ALBINO RATS, CFE STRAIN, WT 76-154 G, GIVEN 7 DAILY DOSES OF 150 MG/KG/DAY BY GASTRIC INTUBATION, SHOWED SIGNIFICANT INCREASES IN HEXOBARBITONE OXIDASE (1.70 UMOLE/HR/G LIVER) & AMINOPYRINE DEMETHYLASE ACTIVITY (0.133 UMOLE/HR/G LIVER), & A 5.4% INCREASE IN LIVER WT. THERE WAS NO CHANGE IN LIVER WT 24 HR AFTER SINGLE DOSE OF 1.5 MMOLE/KG. NO CORRELATION WAS OBSERVED BETWEEN ENZYME INDUCTION & PROTEIN-BINDING CAPACITY OR SOLUBILITY IN LIPID MICELLES, & ONLY MODERATE CORRELATION TO PI VALUES (LOG PARTITION COEFFICIENT MINUS LOG PARTITION COEFFICIENT OF PHENOL) WAS FOUND. THERE WAS NO SIGNIFICANT EFFECT ON UDPG DEHYDROGENASE INDUCTION.

The rate constant for the vapor-phase reaction of 2-t-butyl-4-methylphenol with photochemically produced hydroxyl radicals has been estimated as 5X10-11 cu cm/molecule-sec at 25 °C(SRC) using a structure estimation method(1,SRC). This corresponds to an atmospheric half-life of about 7.7 hours at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm(1,SRC). Reaction of phenols with nitrate radicals may also be an important process(2,SRC).

DRINKING WATER: 2-t-Butyl-4-methylphenol has been qualitatively identified in drinking water(1).

SURFACE WATER: 2-t-Butyl-4-methylphenol has been identified as a main component in Rhine River water and in shore filtered (activated carbon) Rhine water solvent extract(1).

2-t-Butyl-4-methylphenol's production and use as an antioxidant may result in its release to the environment through various waste streams. 2-t-Butyl-4-methylphenol has been identified in drinking water and in the Rhine River. If released to soil, 2-t-butyl-4-methylphenol will have no mobility. Volatilization of 2-t-butyl-4-methylphenol may be important from moist soil surfaces. If released to water, 2-t-butyl-4-methylphenol may adsorb to suspended solids and sediment. 2-t-Butyl-4-methylphenol may volatilize from water surfaces with estimated half-lives for a model river and model lake of 31 and 227 days, respectively. An estimated BCF value of 610 suggests that bioconcentration of 2-t-butyl-4-methylphenol will be high in aquatic organisms. Insufficient data are available to determine the rate or importance of biodegradation of 2-t-butyl-4-methylphenol in soil or water. If released to the atmosphere, 2-t-butyl-4-methylphenol will exist primarily in the vapor phase in the ambient atmosphere. Vapor-phase 2-t-butyl-4-methylphenol is degraded in the atmosphere by reaction with photochemically produced hydroxyl radicals; the half-life for this reaction in air is estimated to be about 7.7 hours. Reaction with nitrate radicals may also be important. Particulate-phase 2-t-butyl-4-methylphenol may be physically removed from the air by wet and dry deposition. The general population may be exposed to 2-t-butyl-4-methylphenol through contaminated drinking water and handling and use of numerous products formulated with the antioxidant. (SRC)