m-Tolualdehyd

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 53(SRC), determined from a structure estimation method(2), indicates that 3-methylbenzaldehyde is expected to have high mobility in soil(SRC). Volatilization of 3-methylbenzaldehyde from moist soil surfaces is expected to be an important fate process(SRC) given an estimated Henry's Law constant of 3.0X10-5 atm-cu m/mole(SRC), developed using a fragment constant estimation method(3). 3-Methylbenzaldehyde is not expected to volatilize from dry soil surfaces(SRC) based upon an estimated vapor pressure of 0.38 mm Hg(SRC), determined from a fragment constant method(4). Based on limited information, 3-methylbenzaldehyde is expected to biodegrade in soil(SRC). A Pseudomonas strain was able to utilize 3-methylbenzaldehyde as the sole carbon source(5); a yeast strain grown with both this compound and either sucrose or pyruvate biodegraded 3-methylbenzaldehyde to the respective aromatic carbinol or alcohol(6).

AQUATIC FATE: Based on a classification scheme(1), an estimated Koc value of 53(SRC), determined from a structure estimation method(2), indicates that 3-methylbenzaldehyde is not 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 3.0X10-5 atm-cu m/mole(SRC), developed using a fragment constant estimation method(4). Using this Henry's Law constant and an estimation method(3), volatilization half-lives for a model river and model lake are 1.5 and 14 days, respectively(SRC). According to a classification scheme(5), an estimated BCF of 11(SRC), from an estimated log Kow of 2.26(6) and a regression-derived equation(7), suggests the potential for bioconcentration in aquatic organisms is low(SRC). 3-Methylbenzaldehyde is not expected to undergo hydrolysis in the environment due to the lack of functional groups that hydrolyze under environmental conditions(3). Based on limited data, biodegradation of 3-methylbenzaldehyde will take place in water. A Pseudomonas strain was able to utilize 3-methylbenzaldehyde as the sole carbon source(8); a yeast strain grown with both this compound and either sucrose or pyruvate biodegraded 3-methylbenzaldehyde to the respective aromatic carbinol or alcohol(9).

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), 3-methylbenzaldehyde, which has an estimated vapor pressure of 0.38 mm Hg at 25 °C(SRC), determined from a fragment constant method(2), is expected to exist solely as a vapor in the ambient atmosphere. Vapor-phase 3-methylbenzaldehyde 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 23 hrs(SRC), calculated from its rate constant of 1.7X10-11 cu cm/molecule-sec at 25 °C(3). The reactivity of 3-methylbenzaldehyde (1 ppm) with NOx (0.5 ppm) in light was measured in a smog chamber as 2.36 ppb/min(4). 3-Methylbenzaldehyde contains chromophores that absorb at wavelengths >290 nm(5) and therefore may be susceptible to direct photolysis by sunlight(SRC).

3-Methylbenzaldehyde has been possibly identified in exhaust gases from gasoline engines, diesel engines and in diesel blowby(1). 3-Methylbenzaldehyde was found in highway tunnels in Tuscarora; light duty trucks emitted 0.067 mg/km traveled or 0.238 mg/L fuel used, heavy duty trucks emitted 1.062 mg/km traveled or 1.594 mg/L fuel used(2). 3-Methylbenzaldehyde was detected in the emissions from ten four-stroke lawn mower engines at 0.13% of total emissions(3). Fine aerosol emission rates of 3-methylbenzaldehyde from heavy-duty diesel trucks, noncatalyst-equipped and catalyst-equipped automobiles were 1.6, 3.5 and 0.53 ug/km, respectively(4). 3-Methylbenzaldehyde was not detected in road dust particles collected from paved streets in a residential area of Pasadena, CA in May 1988, was detected in brake lining particles at a concn of 0.11 ug/g of particle sample and in tire wear particles at a concn of 1.4 ug/g of particle sample(5). Operation of a four-stroke outboard motor resulted in the exhaust emission of 6.4 mg/10 min of 3-methylbenzaldehyde into the water(6).

3-Methylbenzaldehyde/4-methylbenzaldehyde was measured in the emissions of burnt wood at 12 and 27 mg/kg of pine and eucalyptus, but was not detected in the emissions of burnt oak(1).

Using a structure estimation method based on molecular connectivity indices(1), the Koc of 3-methylbenzaldehyde can be estimated to be 53(SRC). According to a classification scheme(2), this estimated Koc value suggests that 3-methylbenzaldehyde is expected to high mobility in soil.

URBAN/SUBURBAN: 3-Methylbenzaldehyde, analyzed in Athens, Greece, June to December 2000, was detected at Patission Street at concns of 2.4-3.9 ug/cu m(1). 3-Methylbenzaldehyde was detected in air from San Paulo, Brazil at 0.090-0.831 ppb in samples taken July 1988(2). 3-Methylbenzaldehyde was found at an avg concn of 0.24 ppb in Los Angeles(3).

RURAL/REMOTE: 3-Methylbenzaldehyde, analyzed outside of Athens, Greece, June to December 2000, was detected at Likovrisi at concns of 2.4-2.8 ug/cu m(1). 3-Methylbenzaldehyde was identified in forest air collected in the Southern Black Forest, Germany, at unreported concentrations(2).

SOURCE DOMINATED: A field monitoring study along a highway in Raleigh, NC in May 1983 detected 3-methylbenzaldehyde levels of 3.01-14.27 ppb; the primary source of the 3-methylbenzaldehyde was considered to be exhaust from cars and trucks(1).

The primary source of the 3-methylbenzaldehyde was considered to be exhaust from cars and trucks(1) and has been detected in exhaust from light duty trucks(2), heavy duty trucks(2), heavy-duty diesel trucks(3), noncatalyst-equipped and catalyst-equipped automobiles(3), four-stroke lawn mower engines(4) and four-stroke outboard motors(5). 3-Methylbenzaldehyde was also detected in brake lining particle samples and in tire wear particle samples(6).

PURE CULTURE: A Pseudomonas strain, isolated from soil, was able to utilize 3-methylbenzaldehyde as the sole carbon source, giving 0.22, 0.27, and 0.40 um O2 consumed/min/mg dry weight cells, for cells previously grown on m-xylene, p-xylene, and p-methylbenzyl alcohol, respectively(1). The rates of formation of aromatic carbinol and aromatic alcohol from a yeast culture grown in both 3-methylbenzaldehyde and sucrose are 0.45 and 0.87 g/L, respectively for a 1 hr incubation(2). The rates of formation of aromatic carbinol and aromatic alcohol from a yeast culture grown in both 3-methylbenzaldehyde and pyruvate are 1.35 and 0.20 g/L, respectively, for a 1 hr incubation(2).

An estimated BCF of 11 was calculated in fish for 3-methylbenzaldehyde(SRC), using an estimated log Kow of 2.26(1) and a regression-derived equation(2). According to a classification scheme(3), this BCF suggests the potential for bioconcentration in aquatic organisms is low(SRC).

The Henry's Law constant for 3-methylbenzaldehyde is estimated as 3.0X10-5 atm-cu m/mole(SRC) using a fragment constant estimation method(1). This Henry's Law constant indicates that 3-methylbenzaldehyde is expected to volatilize from water surfaces(2). 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)(2) is estimated as 1.5 days(SRC). The volatilization half-life from a model lake (1 m deep, flowing 0.05 m/sec, wind velocity of 0.5 m/sec)(2) is estimated as 14 days(SRC). 3-Methylbenzaldehyde's Henry's Law constant indicates that volatilization from moist soil surfaces may occur(SRC). 3-Methylbenzaldehyde is not expected to volatilize from dry soil surfaces(SRC) based upon an estimated vapor pressure of 0.38 mm Hg(SRC), determined from a fragment constant method(3).

/LABORATORY ANIMALS: Acute Exposure/ Tolualdehyde was a skin irritant in rabbits. ...Sensitization reactions were apparently induced in guinea-pigs. /Tolualdehydes/

/LABORATORY ANIMALS: Acute Exposure/ In rats, the acute oral and dermal toxicity were low ... /Tolualdehydes/

/LABORATORY ANIMALS: Subchronic or Prechronic Exposure/ In rats, ... pituitary gland weight was reduced following repeated oral administration. /Tolualdehydes/

/GENOTOXICITY/ There was no evidence of mutagenicity in Ames bacterial tests. /Tolualdehydes/

The rate constant for the vapor-phase reaction of 3-methylbenzaldehyde with photochemically-produced hydroxyl radicals has been measured as 1.7X10-11 cu cm/molecule-sec at 25 °C(1). This corresponds to an atmospheric half-life of about 23 hours at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm(1). The reactivity of 3-methylbenzaldehyde was measured using the smog chamber method where the aldehyde is irradiated in a mixture with nitric oxide and air; the reactivity of 1 ppm of 3-methylbenzaldehyde with 0.5 ppm of NOx was measured as 2.36 ppb/min(2). 3-Methylbenzaldehyde is not expected to undergo hydrolysis in the environment due to the lack of functional groups that hydrolyze under environmental conditions(3). 3-Methylbenzaldehyde contains chromophores that absorb at wavelengths >290 nm(3) and therefore may be susceptible to direct photolysis by sunlight(SRC).