4-Methylquinoline

SRP: The most favorable course of action is to use an alternative chemical product with less inherent propensity for occupational exposure or environmental contamination. Recycle any unused portion of the material for its approved use or return it to the manufacturer or supplier. Ultimate disposal of the chemical must consider: the material's impact on air quality; potential migration in soil or water; effects on animal, aquatic, and plant life; and conformance with environmental and public health regulations.

Quinoline and all 7 positional isomers of methylquinoline were assayed for tumor-initiating activity on the skin of SENCAR female mice with promotion by tetradecanoyl phorbol acetate. ... Quinoline induced tumors in 53% of the mice (0.73 tumors per animal). While 2-, 3-, 5- and 7-methylquinoline did not exhibit significant tumorigenic activity in this assay, 4-methylquinoline induced tumors in 45% of the mice (0.90 tumors per animal). 8-Methylquinoline induced tumors in 45% of the mice (0.66 tumors per animal).

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 630(SRC), determined from a log Kow of 2.61(2) and a regression-derived equation(3), indicates that 4-methylquinoline is expected to have low mobility in soil(SRC). The pKa of 4-methylquinoline is 5.67(4), indicating that this compound will partially exist in cation form in the environment and cations generally adsorb to organic carbon and clay more strongly than their neutral counterparts(5). Volatilization of 4-methylquinoline from moist soil surfaces is not expected to be an important fate process(SRC) given an estimated Henry's Law constant of 7.6X10-7 atm-cu m/mole(SRC), using a fragment constant estimation method(6). 4-Methylquinoline is not expected to volatilize from dry soil surfaces(SRC) based upon a vapor pressure of 6.4X10-3 mm Hg(7). Based on ananerobic studies in water, 4-methylquinoline is expected to degrade in soil under anaerobic conditions(SRC). Slurries from methanogenic freshwater sediment transformed 4-methylquinoline after anaerobic incubation for 106 days at 25 °C(8).

AQUATIC FATE: Based on a classification scheme(1), an estimated Koc value of 630(SRC), determined from a log Kow of 2.61(2) and a regression-derived equation(3), indicates that 4-methylquinoline 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 7.6X10-7 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 18 and 200 days, respectively(SRC). The pKa of 4-methylquinoline is 5.67(5), indicating that this compound will partially exist in cation form in the environment and cations generally adsorb to organic carbon and clay more strongly than their neutral counterparts(6). According to a classification scheme(7), an estimated BCF of 20(SRC), from its log Kow(2) and a regression-derived equation(8), suggests the potential for bioconcentration in aquatic organisms is low(SRC). Slurries from methanogenic freshwater sediment transformed 4-methylquiloline after anaerobic incubation for 106 days at 25 °C(9). Using groundwater medium from a creosote contaminated medium (i.e., from American Creosote Works site in Pensacola, FL), 4-methylquinoline degraded from an initial concn of 0.7 ug/ml to 0.2 ug/ml in 14 days(10). The major product of anaerobic degradation of 4-methylquinoline is 4-methyl-2(1H)-quinolinone while the minor products are 1,4-dimethyl-2(1H)-quinolinone and 2-methoxy-4-methyl-quinoline(11).

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), 4-methylquinoline, which has a vapor pressure of 6.4X10-3 mm Hg at 25 °C(2), is expected to exist solely as a vapor in the particulate phase in the ambient atmosphere(SRC). Vapor-phase 4-methylquinoline 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 13 hrs(SRC), calculated from its rate constant of 3.0X10-11 cu cm/molecule-sec at 25 °C(SRC) that was derived using a structure estimation method(3). 4-Methylquinoline is expected to undergo direct photolysis based on adsorption of light at wavelengths >290 nm(4).

The Koc of 4-methylquinoline is estimated as 630(SRC), using a log Kow of 2.61(1) and a regression-derived equation(2). According to a classification scheme(3), this estimated Koc value suggests that 4-methylquinoline is expected to have low mobility in soil(SRC). The pKa of 4-methylquinoline is 5.67(4), indicating that this compound will partially exist in cation form in the environment and cations generally adsorb to organic carbon and clay more strongly than their neutral counterparts(5).

AEROBIC: 4-Methylquinoline degraded using a pure culture (Lep1) under aerobic conditions(1). Degradation was characterized by relatively long and variable lag periods despite nearly identical population densities in replicate flasks(1). 4-Methylquinoline degraded to 2-hydroxy-4-methyl-quinoline and then to hydroxy-4-methylcoumarin(1).

ANAEROBIC: Slurries from methanogenic freshwater sediment transformed 4-methylquiloline after anaerobic incubation for 106 days at 25 °C(1). The unidentified transformation products of 4-methylquinoline accumulated and were not further degraded(1). Using groundwater medium from a creosote contaminated medium (i.e., from American Creosote Works site in Pensacola, FL), 4-methylquinoline degraded from an initial concn of 0.7 ug/ml to 0.2 ug/ml in 14 days(2). The major product of anaerobic degradation of 4-methylquinoline is 4-methyl-2(1H)-quinolinone while the minor products are 1,4-dimethyl-2(1H)-quinolinone and 2-methoxy-4-methyl-quinoline(3).

An estimated BCF of 20 was calculated for 4-methylquinoline(SRC), using a log Kow of 2.61(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 4-methylquinoline is estimated as 7.6X10-7 atm-cu m/mole(SRC) using a fragment constant estimation method(1). This Henry's Law constant indicates that 4-methylquinoline is expected to be essentially nonvolatile from water surfaces(2). 4-Methylquinoline is not expected to volatilize from dry soil surfaces(SRC) based upon a vapor pressure of 6.4X10-3 mm Hg(3).

/LABORATORY ANIMALS: Subchronic or Prechronic Exposure/ Outbred female Hfd:SENCAR mice (n=30) age 50 to 55 days were treated on their shaved backs with 0.1 ml of a 0.75% 4-methylquinoline solution in acetone 10 times, every other day, producing a total initiating dose of 7.5 mg. Negative and positive control animals (n=40) were treated with acetone alone or with benzo[a]pyrene (total dose = 0.03 mg), respectively. Ten days following the last treatment with initiator, 2.0 ug TPA was applied twice weekly for 18 weeks. Animals were monitored for skin tumors weekly during promotion period. Skin tumor incidences after 18 weeks of promotion (<23 weeks after exposure to 4-methylquinoline or benzo[a]pyrene) /were presented as follows,11 of 25 animals exposed to 4-methylquinoline developed skin tumors and 18 of 24 mice exposed to benzo[a]pyrene developed tumors. Both of these results represent a statistically significant increase relative to acetone controls (1/24) by Fisher's exact test (p< 0.005)./

/LABORATORY ANIMALS: Subchronic or Prechronic Exposure/ The relative tumorigenic activity of... 4-methylquinoline... was evaluated in newborn CD-1 mice and Sprague-Dawley rats. In the newborn-mouse bioassay, 0.25, 0.5 or 1.0 mumol of /4-methylquinoline/ in dimethylsulphoxide was administered by ip injection on days 1, 8 and 15 of life, respectively. The bioassay was terminated when the mice were 1 yr old. The incidence of liver tumors observed for those male mice treated with ... 4-methylquinoline was >78%.

/LABORATORY ANIMALS: Subchronic or Prechronic Exposure/ Newborn Sprague-Dawley rats (n=50) were injected subcutaneously on the first day of life with 200 umol/kg body weight 4-methylquinoline, subsequently weekly with 100 umol/kg body weight during weeks two to seven, and finally at 200 umol/kg body weight at the eight week. Injected concentrations were 0.1 M 4-methylquinoline in /dimethylsulphoxide/ (DMSO) for weeks one through four, 0.3 M for weeks five and six, and 1.2 M for weeks seven and eight. Control animals (n=50) received 500 uL DMSO/kg body weight on the first day of life and weekly thereafter for eight weeks.Two percent of 4-methylquinoline treated rat pups died within the first week of life. At four weeks, the animals were separated by sex and observed until the 78 week at which time the animals were killed. Livers and macroscopic lesions were examined histologically. No significantly increased tumor incidence were observed in either male or female rats at any site.

/LABORATORY ANIMALS: Subchronic or Prechronic Exposure/ Quinoline and all 7 positional isomers of methylquinoline were assayed for tumor-initiating activity on the skin of SENCAR female mice with promotion by tetradecanoyl phorbol acetate. ... Quinoline induced tumors in 53% of the mice (0.73 tumors per animal). While 2-, 3-, 5- and 7-methylquinoline did not exhibit significant tumorigenic activity in this assay, 4-methylquinoline induced tumors in 45% of the mice (0.90 tumors per animal). 8-Methylquinoline induced tumors in 45% of the mice (0.66 tumors per animal).

The rate constant for the vapor-phase reaction of 4-methylquinoline with photochemically-produced hydroxyl radicals has been estimated as 3.0X10-11 cu cm/molecule-sec at 25 °C(SRC) using a structure estimation method(1). This corresponds to an atmospheric half-life of about 13 hours at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm(1). 4-Methylquinoline is not expected to undergo hydrolysis in the environment due to the lack of hydrolyzable functional groups(2). 4-Methylquinoline is expected to undergo direct photolysis based on adsorption of light at wavelengths >290 nm(3).

NIOSH (NOES Survey 1981-1983) has statistically estimated that 1,557 workers (276 of these are female) are potentially exposed to 4-methylquinoline in the US(1). Occupational exposure to 4-methylquinoline may occur through dermal contact with this compound at workplaces where 4-methylquinoline is produced or used(SRC). Monitoring data indicate that the general population may be exposed to 4-methylquinoline with the use of this compound for medicinal purposes and as a food additive(SRC).

GROUNDWATER: In 1983, 4-methylquinoline was detected in 2 groundwater wells at an abandoned creosote works located in Pensicola, FL(1). Concns of 4-methylquinoline were 0.21 mg/liter and ranged from 0.00 to 0.02 mg/liter in these groundwater wells(1). In June 1986, the concn of 4-methylquinoline in groundwater was 730 ug/liter at a creosote contaminated site in Pensacola, FL(2). In October, 1986, the concn of 4-methylquinoline in groundwater was <18 ng/liter at a coal tar contaminated site in St. Louis, Park, MN(2).

4-Methylquinoline is a food additive permitted for direct addition to food for human consumption as a synthetic flavoring substance and adjuvant in accordance with the following conditions: a) they are used in the minimum quantity required to produce their intended effect, and otherwise in accordance with all the principles of good manufacturing practice, and 2) they consist of one or more of the following, used alone or in combination with flavoring substances and adjuvants generally recognized as safe in food, prior-sanctioned for such use, or regulated by an appropriate section in this part.