2-Methylpyrene

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 87,000(SRC), determined from a structure estimation method(2), indicates that 2-methylpyrene is expected to be immobile in soil(SRC). Volatilization of 2-methylpyrene from moist soil surfaces may occur given an estimated Henry's Law constant of 3.2X10-6 atm-cu m/mole(SRC), using a fragment constant estimation method(2). However, adsorption to soil is expected to attenuate volatilization(SRC). 2-Methylpyrene is not expected to volatilize from dry soil surfaces(SRC) based upon an estimated vapor pressure of 3.1X10-7 mm Hg at 25 °C(SRC), determined from a fragment constant method(2). PAHs with four or more rings, such as 2-methylpyrene, are generally expected to be resistant to biodegradation(3). By analogy to pyrene, biodegradation is expected to occur slowly in soils, with estimated half-lives ranging from several weeks to years(4,5). Faster biodegradation rates occur with exposure to acclimated microbes(6). Soil microcosm studies using three industrial soils from Austria found pronounced biodegradation of pyrene in one soil (about 65-75% over 65 days of incubation), but only slight biodegradation in the other two soils(7). By analogy to pyrene which absorbs strongly at wavelengths >290 nm(9), 2-methylpyrene is expected to be susceptible to direct photolysis on surfaces exposed to sunlight(SRC).

AQUATIC FATE: Based on a classification scheme(1), an estimated Koc value of 87,000(SRC), determined from a structure estimation method(2), indicates that 2-methylpyrene is expected to adsorb to suspended solids and sediment(SRC). Volatilization from water surfaces is expected(3) based upon an estimated Henry's Law constant of 3.2X10-6 atm-cu m/mole(SRC), developed using a fragment constant estimation method(2). Using this Henry's Law constant and an estimation method(3), volatilization half-lives for a model river and model lake are 17 and 130 days, respectively(SRC). However, volatilization from water surfaces is expected to be attenuated by adsorption to suspended solids and sediment in the water column. The estimated volatilization half-life from a model pond is >10 years if adsorption is considered(4). According to a classification scheme(5), an estimated BCF of 1920(SRC), from an estimated log Kow of 5.48(2) and a regression-derived equation(2), suggests the potential for bioconcentration in aquatic organisms is very high, provided the compound is not metabolized by the organism(SRC). However, 2-methylpyrene may not bioconcentrate in aquatic organisms which contain microsomal oxidase, such as some fish, as this enzyme enables the rapid metabolism of certain polycyclic aromatic hydrocarbons(6). A measured fish biotransformation half-life of 2.08 days has been reported for the analogous pyrene(7). The near surface half-life for direct photolysis of analgous pyrene in water by sunlight was measured as 0.68 hours(8) and 0.85 hours(9). PAHs with four or more rings, such as 2-methylpyrene, are generally expected to be resistant to biodegradation(10). By analogy to pyrene, biodegradation is expected to occur slowly in soils, with estimated half-lives ranging from several weeks to years(11,12). Faster biodegradation rates occur with exposure to acclimated microbes(13). Hydrolysis is not expected to be an important environmental fate process since this compound lacks functional groups that hydrolyze under environmental conditions(3).

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), 2-methylpyrene, which has an estimated vapor pressure of 3.1X10-7 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-methylpyrene 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 2.9 hours(SRC), calculated from its rate constant of 1.3X10-10 cu cm/molecule-sec at 25 °C(SRC) that was derived using a structure estimation method(2). Particulate-phase 2-methylpyrene may be removed from the air by wet and dry deposition(SRC). By analogy to pyrene which absorbs strongly at wavelengths >290 nm(3,4), 2-methylpyrene is expected to be susceptible to direct photolysis by sunlight(SRC).

A 2-methylpyrene concentration of 731 ng/uL in timber products and 16 ng/uL in coal mining was identified in an industrial wastewater survey in which samples collected between November 1, 1979 to November 1, 1981 were analyzed for organic pollutants other than Priority Pollutants(1). The concentration of 2-methylpyrene in diluted heavy-duty diesel exhausts was determined to average 2.0 ug/km (range of 0.11 to 4.8 ug/km) in particulate matter(2). 2-Methylpyrene has been detected in combustion emissions from fuel oil, biomass and coal(3). Lawn mower exhaust emissions contained 2-methylpyrene(4).

Using a structure estimation method based on molecular connectivity indices(1), the Koc of 2-methylpyrene can be estimated to be 87,000(SRC). According to a classification scheme(2), this estimated Koc value suggests that 2-methylpyrene is expected to be immobile in soil(SRC).

URBAN/SUBURBAN: Methylpyrene was identified in the air particulate matter collected from the lightly industrialized urban area of Christchurch, New Zealand, concentration not reported(1). Outdoor residential air sampled during Feb and Mar 2003 at Hagfors, Sweden had mean and median 2-methylpyrene concentrations of 0.42 and 0.20 ng/cu m respectively(2). Atmospheric air with particle samples (PM2.5) collected from three northeastern US sites (Boston, MA, Rochester, NY and Quabbin Resevoir, MA) contained 2-methylpyrene concentrations of 220, 41 and 15 pg/cu m respectively(3).

INDOOR AIR: Indoor air in 13 Swedish homes using wood-burning appliances had mean and median pyrene levels of 0.30 and 0.15 ng/cu m, respectively, while 10 homes not using wood-burning had levels of below quantification limits to 0.27 ng/cu m(1).

The mean concentration of 2-methylpyrene in seston (planktonic bacteria, phtyoplankton and zooplankton) and blue mussel (Mytilus edulis, L.) soft parts was determined to be 14 and 1.0 ng/g dry wt, respectively. Mussels were collected in the open northern Baltic Sea from the early summer to early autumn of 1985 and 1986(1). 2-Methylpyrene was identified in purified rainbow trout (Oncorhynchus mykiss) muscle at a concentration 0.058 ng/g following exposure of the fish in the laboratory for several months to lubricating oil and sewer sludge(2).

2-Methylpyrene is one of many polycyclic aromatic hydrocarbons (PAH) that occur as ubiquitous products of incomplete combustion of fossil fuels, wood, diesel oils and gasoline fuels(1). 2-Methylpyrene's presence in exhaust from these combustion sources will release the compound directly to the environment(SRC). 2-Methyl pyrene occurs in tobacco smoke(2), charcoal smoke, and meat smoke from charcoal grilling(3). 2-Methylpyrene has been identified as a constituent of gasoline and diesel fuels(4,5).

AEROBIC: Polycyclic aromatic hydrocarbons (PAHs) with four or more rings, such as 2-methylpyrene, are generally expected to be resistant to biodegradation(1). Biodegradation of the analogous compound pyrene is expected to occur slowly in soils, with estimated half-lives ranging from several weeks to years(2,3). Faster biodegradation rates occur with exposure to acclimated microbes(4). Soil microcosm studies using three industrial soils from Austria found pronounced biodegradation of pyrene in one soil (about 65-75% over 65 days of incubation), but only slight biodegradation in the other two soils(5).

PURE CULTURE: 2-Methylpyrene, present in Arabian light crude oil, was determined to be resistant to degradation by pure culture strains of Pseudomonas sp. isolated from tanker ballast waters(1).

Toxic pollutant designated pursuant to section 307(a)(1) of the Federal Water Pollution Control Act and is subject to effluent limitations. /Polynuclear aromatic hydrocarbons (including benzanthracenes, benzopyrenes, benzofluoranthene, chrysenes, dibenz-anthracenes, and indenopyrenes)/

For the maximum protection of human health from the potential carcinogenic effects of exposure to polynuclear aromatic hydrocarbons through ingestion of contaminated water and contaminated aquatic organisms, the ambient water concentration should be zero, based on the nonthreshold assumption for this chemical. However, zero level may not be attainable at the present time. Therefore, the levels which may result in incremental increase of cancer risk over the lifetime are estimated at 1X10-5, 1X10-6, and 1X10-7. The corresponding recommended criteria are 28.0 ng/L, 2.8 ng/L, and 0.28 ng/L, respectively. If these estimates are made for consumption of aquatic organisms only, excluding consumption of water, the levels are 311.0 ng/L, 31.1 ng/L, and 3.11 ng/L, respectively. /Polynuclear aromatic hydrocarbons/.