3-Ethylphenol

TERRESTRIAL FATE: Based on a recommended classification scheme(1), an estimated Koc value of 480(SRC), determined from a measured log Kow(2) and a recommended regression-derived equation(3), indicates that 3-ethylphenol will have moderate mobility in soil(SRC). Based on limited data, biodegradation of this compound is likely. A system where water was passed through contaminated soil (initial 3-ethylphenol concn = 73 ug/L) and then through a upflow aerated column was capable of 93% removal in 37 days(4). 3-Ethylphenol's measured and estimated values for vapor pressure(5) and Henry's Law constant(6,SRC), respectively, indicate that volatilization from dry and moist soil surfaces is possible, but will not be a major fate process for this compound(SRC).

AQUATIC FATE: Based on a recommended classification scheme(1), an estimated Koc value of 480(SRC), determined from a measured log Kow(2) and a recommended regression-derived equation(3), indicates that 3-ethylphenol may adsorb to suspended solids and sediment(SRC) in the water. Based on limited data, biodegradation of this compound is likely. A system where water was passed through contaminated soil (initial 3-ethylphenol concn = 73 ug/L) and then through a upflow aerated column was capable of 93% removal in 37 days(4). 3-Ethylphenol should volatilize from water surfaces based on an estimated Henry's Law constant of 1.1X10-6 atm-cu m/mole(SRC), developed using a fragment constant estimation method(5). Estimated half-lives for a model river and model lake are 37 and 274 days, respectively(3,SRC). An estimated BCF value of 40(3,SRC), from an experimental log Kow(2), suggests that 3-ethylphenol may bioconcentrate in aquatic organisms(SRC) according to a recommended classification scheme(6).

ATMOSPHERIC FATE: According to a suggested classification scheme(1), a measured vapor pressure of 0.05 mm Hg at 25 °C(2) indicates that 3-ethylphenol will mainly exist in the vapor phase in the ambient atmosphere. Vapor-phase 3-ethylphenol 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 5 hours(3,SRC).

Final effluent collected from the Los Angeles County wastewater treatment plant contained 3-ethylphenol at an average concentration of 15 ug/L(1). 3-Ethylphenol was detected at unreported concentrations in a groundwater plume emanating from the Hipps Road Landfill, Florida(2). 3-Ethylphenol was detected in industrial wastewater from the following industries: petroleum refining (1 of 21 extracts), organic chemicals (1 of 31 extracts), and publicly-owned treatment works (1 in 44 extracts)(3). 3- and 4-ethylphenol (mixed) were detected in cigarette smoke at 1.2-2.8 mg/100 cigarettes(4). 3-Ethylphenol was detected in wastewater from the gasification of Indian Head lignite coal(5).

The Koc of 3-ethylphenol is estimated as approximately 480(SRC), using a measured log Kow of 2.40(1) and a regression-derived equation(2,SRC). According to a recommended classification scheme(3), this estimated Koc value suggests that 3-ethylphenol has moderate mobility in soil(SRC).

A xylenol fraction boiling between 216 and 218 °C containing predominantly 3- and 4-ethylphenol is obtained from brown coal low-temperature tar and used in the varnish industry.

Volcanic ash from Mount St. Helens, following th May 18, 1980 eruption, contained 3-ethylphenol(1).

3-Ethylphenol's production and use in the manufacture of photochemicals and varnishes(1), may result in its release to the environment through various waste streams(SRC). 3-Ethylphenol is also released in effluent streams from coal gasification plants(3) and from cigarette smoke(2).

A lab-scale, upflow aerated column receiving water that had first passed through a soil sample, obtained from a former asphalt production plant, (3-ethylphenol influent initially at 73 ug/L) was capable of 93% removal of this compound within 37 days(1). An on-site (at the production plant) upflow aerated column and trickling filter, after 38 days of operation, removed 86% and 22% of the initial concentration of p-ethylphenol, respectively(1). Differences between lab scale and on-site reactors were due to differences in the hydraulic load(1). Pseudomonas strain FH23, isolated by enrichment culture with 4-hydroxybiphenyl, had a oxygen uptake rate of 9 nmol/min/mg protein when grown with 3-ethylphenol as the sole carbon source(2).

An estimated BCF value of 40 was calculated for 3-ethylphenol(SRC), using a measured log Kow of 2.40(1) and a recommended regression-derived equation(2). According to a recommended classification scheme(3), this BCF value suggests that bioconcentration in aquatic organisms may be an important fate process(SRC).

The Henry's Law constant for 3-ethylphenol is estimated as 1.1X10-6 atm-cu m/mole(SRC) using a fragment constant estimation method(1). This value indicates that 3-ethylphenol 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 37 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 274 days(2,SRC). 3-Ethylphenol's values for vapor pressure(4) and Henry's Law constant(1,SRC) indicate that volatilization from dry and moist soil surfaces is possible, but not likely to be a major fate process for this compound(SRC).

The rate constant for the vapor-phase reaction of 3-ethylphenol with photochemically produced hydroxyl radicals has been estimated as 8.4X10-11 cu cm/molecule-sec at 25 °C(SRC) using a structure estimation method(1,SRC). This corresponds to an atmospheric half-life of about 5 hours at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm(1,SRC). 3-Ethylphenol has a measured pKa of 9.9, indicating that under most environmental conditions this compound will exist mainly as the non-dissociated form(2).