Dibenzofuran

EYES: First check the victim for contact lenses and remove if present. Flush victim's eyes with water or normal saline solution for 20 to 30 minutes while simultaneously calling a hospital or poison control center. Do not put any ointments, oils, or medication in the victim's eyes without specific instructions from a physician. IMMEDIATELY transport the victim after flushing eyes to a hospital even if no symptoms (such as redness or irritation) develop.

SMALL SPILLS AND LEAKAGE: Should a spill occur while you are handling this chemical, FIRST REMOVE ALL SOURCES OF IGNITION, then you should dampen the solid spill material with 60-70% ethanol and transfer the dampened material to a suitable container. Use absorbent paper dampened with 60-70% ethanol to pick up any remaining material. Seal the absorbent paper, and any of your clothes, which may be contaminated, in a vapor-tight plastic bag for eventual disposal. Solvent wash all contaminated surfaces with 60-70% ethanol followed by washing with a soap and water solution. Do not reenter the contaminated area until the Safety Officer (or other responsible person) has verified that the area has been properly cleaned.

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.

30 [mg/m3]

330 [mg/m3]

2000 [mg/m3]

RECOMMENDED RESPIRATOR: Where the neat test chemical is weighed and diluted, wear a NIOSH-approved half face respirator equipped with an organic vapor/acid gas cartridge (specific for organic vapors, HCl, acid gas and SO2) with a dust/mist filter. (NTP, 1992)

LC50 Daphnia magna (Water flea) 7500 ug/L/24 hr (95% CI: 4400-13000), static

LC50 Daphnia magna (Water flea) 1700 ug/L/48 hr (95% CI: 1100-2700), static

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 4,200(SRC), determined from a log Kow of 4.12(2) and a regression-derived equation(3), indicates that dibenzofuran is expected to have slight mobility in soil(SRC). Volatilization of dibenzofuran from moist soil surfaces is expected to be an important fate process(SRC) given an estimated Henry's Law constant of 2.1X10-4 atm-cu m/mole(SRC), derived from its vapor pressure, 0.00248 mm Hg(4), and water solubility, 3.1 mg/l(5). However, adsorption to soil is expected to attenuate volatilization(SRC). Dibenzofuran is not expected to volatilize from dry soil surfaces(SRC) based upon its vapor pressure(4). Photoreactor studies indicate that photodegradation may occur in surface soil but degradation rates appear to be slow(6). Screening tests in water indicate that dibenzofuran is not likely to be readily biodegradable(SRC). Dibenzofuran, present at 100 mg/l, reached 0% of its theoretical BOD in 4 weeks using an activated sludge inoculum at 30 mg/l and the Japanese MITI test(7). However, indigenous soil microorganisms at contaminated sites can degrade dibenzofuran if stimulated(8,9). At a creosote-contaminated site, the concn of dibenzofuran at 8 locations (mean, 652 mg/kg) was reduced by an avg of 83% in 4 months(9).

AQUATIC FATE: Based on a classification scheme(1), an estimated Koc value of 4,200(SRC), determined from a log Kow of 4.12(2) and a regression-derived equation(3), indicates that dibenzofuran 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 2.1X10-4 atm-cu m/mole(SRC), derived from its vapor pressure, 0.00248 mm Hg(4), and water solubility, 3.1 mg/l(5). Using this Henry's Law constant and an estimation method(3), volatilization half-lives for a model river and model lake are 5 hours and 7 days, respectively(SRC). However, volatilization from water surfaces is expected to be attenuated by adsorption to suspended solids and sediment in the water column(SRC). The estimated volatilization half-life from a model pond is 82 days if adsorption is considered(6). According to a classification scheme(7), BCF values for fish of 524 to 947(5,8) are high and from 1,100 to 2,420(5,8,9) are very high(SRC). However, rapid elimination of dibenzofuran would reduce the BCF potential(SRC). Over 97% of the accumulated dibenzofuran was eliminated in 2 days during depuration tests in fathead minnow(10). Screening tests indicate that dibenzofuran is not readily biodegradable(SRC). Dibenzofuran, present at 100 mg/l, reached 0% of its theoretical BOD in 4 weeks using an activated sludge inoculum at 30 mg/l and the Japanese MITI test(8). However, dibenzofuran was degraded in a few days in laboratory studies using subsurface materials which had been contaminated by creosote chemicals(11). The rate of dibenzofuran degradation in studies using pristine subsurface materials was relatively slow and not much faster than in autoclaved controls, 3.9% per week(11). Restriction of oxygen supply in the non-sterile experiments significantly lowered the degradation rate(11). Once microbial adaptation had occurred, dibenzofuran rapidly biotransformed as long as an adequate oxygen supply was present(11).

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), dibenzofuran, which has a vapor pressure of 0.00248 mm Hg at 25 °C(2), is expected to exist solely as a vapor in the ambient atmosphere(SRC). However, a small fraction (about 2.4%) exists in the particulate phase(3-5). Vapor-phase dibenzofuran 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 4 days(SRC), calculated from its rate constant of 3.9X10-12 cu cm/molecule-sec at 25 °C(6). For particle-associated dibenzofuran, the dominant tropospheric removal processes are expected to be wet and dry deposition; a tropospheric lifetime of >10 days is expected which is sufficient for long-range transport to occur(7). Rainwater monitoring indicates that both vapor-phase and particulate dibenzofuran are removed from air via wet deposition(3,4). Washout ratios (concn in rainwater/concn in air) are approximately 1000(5). Dibenzofuran absorbs little UV light above 300nm, but UV absorption rises sharply below 300 nm(7), indicating a potential for direct photolysis in the atmosphere(SRC).

The concn of dibenzofuran detected in Finnish, margarines, and vegetable oils ranged from 0.08 to 0.64 ug/kg(1). The mean concn of dibenzofuran in various Finnish cereal products were (product, concn in ug/kg): bolted wheat flour (n=7), 2.1; bolted rye flour (n=1), 1.4; rolled oats (n=2), 4.1; milled oats (n=3), 2.6; milled wheat (n=19), 1.0; bran (n=1), 4.7(2). The concn of dibenzofuran in smoked oats, barley and beans was 160 ug/kg when the wet grain was exposed to smoke and then milled and 3.1 ug/kg when the bran was separated after smoking and before milling(2).

/FIELD STUDIES OTHER TERRESTRIAL SPECIES/ The effects of eight polycyclic aromatic compounds (PACs) on the survival and reproduction of the enchytraeid worm Enchytraeus crvpticus were investigated in an agricultural soil with an organic carbon content of 1.6%. With the exception of acridine, which showed a strong binding to the test soil and a subsequent low toxicity, polycyclic aromatic hydrocarbons and neutral N-, S-, O-monosubstituted analogues showed a similar toxicity to the enchytraeids. Concentrations estimated to give a 10% reduction of reproductive output (EC10 values) were based on measured initial concentrations and were, for acridine, 310 mg/kg; for carbazole, 19 mg/kg; for dibenzofuran, 36 mg/kg, for dibenzothiophene, 40 and 45 mg/kg (two tests); for fluoranthene, 15 mg/kg; for fluorene, 25 mg/kg; for phenanthrene, 40 mg/kg; and for pyrene, 11 mg/kg.

/FIELD STUDIES OTHER TERRESTRIAL SPECIES/ The effects of eight polycyclic aromatic compounds on the survival and reproduction of the collembolan Folsomia fimetaria L. were investigated in a well-characterized Danish agricultural soil. With the exception of acridine, polycyclic aromatic hydrocarbons (PAHs) and neutral N-, S-, and O-monosubstituted analogues showed similar toxicities to soil collembolans when the results were expressed in relation to total soil concentrations (mg/kg). The estimated concentrations resulting in a 10% reduction of reproductive output (EC10 values) were based on measured initial concentrations and were for acridine 290 mg/kg, carbazole 10 mg/kg, dibenzofuran 19 mg/kg, dibenzothiophene 7.8 mg/kg, fluoranthene 37 mg/kg, fluorene 7.7 mg/kg, phenantrene 23 mg/kg, and pyrene 10 mg/kg. When the EC10 values were converted to soil pore-water concentrations, they showed a highly significant correlation (r2 = 0.71, p < 0.01) to no-observed-effect concentrations for the freshwater crustacean Daphnia magna, as estimated by a quantitative structure activity relation (QSAR) for baseline toxicity (nonpolar narcosis). Only carbazole and acridine were more than two times more toxic (4.9 and 3.1, respectively) than expected from the Daphnia QSAR data.

Three of 6 earthworm samples collected in the vicinity of a manufacturing plant in Czechoslovakia that processed crude tar contained 58.4 to 93.9 ng/g of dibenzofuran(1). The concn of dibenzofuran in the eggs of birds of the Baikal region (Russia) were as follows (all ug/kg dry wt): mallard, 14.6; pintail, <5; shoveler, 51.5; tufted duck, 150.5; pochard, 12.8; goose, 34.4; domestic fowl, 53.6-137.5; heron, 48.2; herring gull, 11.2; common gull, 47.0; common tern, 34.4; black headed gull, 26.5; liapwing, 9.2; slavonian grebe, 64.1; marsh sandpiper, 57.8(2).

Dibenzofuran was identified in fly ash collected from a municipal incinerator in Ontario, Canada(1). Dibenzofuran was found in emissions from a factory producing carbon electrodes; a large gas chromatography peak was evident, but no concns were reported(2). Concn in effluents from a sewage treatment plant in Norway ranged from <57 to 359 ng/l during 1979-80(3). Wastewater from a coal gasification facility estimated to contain 0.5 ppm dibenzofuran(4). Concns in wastewater effluents from coal gasification facilities in Gillette, WY and Morgantown, WV were 0.1 and 72 ppb, respectively(5); concn in a shale oil wastewater was 29 ppb(5). Emissions of dibenzofuran from a diesel-powdered medium duty truck was 28.7 ug dibenzofuran per km in gas-phase and 6.0 ug dibenzofuran per km in the particulate-phase(6).

The Koc of dibenzofuran is estimated as 4,200(SRC), using a log Kow of 4.12(1) and a regression-derived equation(2). According to a classification scheme(3), this estimated Koc value suggests that dibenzofuran is expected to have slight mobility in soil(SRC). Monitoring of dibenzofuran in contaminated groundwater beneath an abandoned creosote facility in Conroe, TX has suggested that leaching of dibenzofuran may be much more important than predicted from estimation methods, although soil from this location had a very low organic content and other co-contaminants present(4). Sorption of creosote compounds (including dibenzofuran) were measured on natural clayey till soil column(5); a Kd of 4.31 l/kg was measured for dibenzofuran (in the presence of other creosote compounds)(5).

URBAN/SUBURBAN: The concn of dibenzofuran was measured with ground level 12-hr high volume samplers in Minneapolis and Salt Lake City between Nov 1988 and Feb 1989 when wood burning would be expected to contribute to atmospheric pollution(1). Hardwood is burned in Minneapolis and softwood in Salt Lake City(1). Dibenzofuran concns at various types of sites were (site description, number of sites, concn): suburban residential (Minneapolis), 5, 13-31 ng/cu m; city res (Minneapolis), 3, 6.5-16 ng/cu m; non-res downtown (Minneapolis), 3, 10-16 ng/cu m; res suburban (Salt Lake City) 3, 22-28 ng/cu m; city res (Salt Lake City), 6, 11-76 ng/cu m; non-res downtown (Salt Lake City), 2, 10-14 ng/cu m(1). The concn of dibenzofuran in the gas-phase in the ambient air of Portland, OR in Feb-Apr 1984 ranged from 13 to 25 ng/cu m(2); the particulate phase concn ranged from 0 to 0.35 ng/cu m(3). The mean concns of dibenzofuran in the gas and particulate phases in Portland were 19 and 0.1 ng/cu m, respectively indicating that only 2.4% of the dibenzofuran was attached to particles(4). A 24-hr air sample collected in December, 1986 in Whitehorse, Yukon contained 2 ppm of dibenzofuran(5).

INDOOR: The concn of dibenzofuran in the air of Finnish saunas ranged from 0.15 to 5.5 ug/cu m(1). The gas-phase concn was generally 5 to 10 times greater than that in the particle phase(1).

RURAL/REMOTE: In 1988, dibenzofuran was qualitatively identified in air at a forest site in West Germany, studied because of severe damage to spruce trees over the previous decade(1).

SOURCE DOMINATED: Ambient air concns ranging from 1.1 to 112.2 ng/cu m were detected in the air of an industrial town in Finland(1). Air monitoring in August and September, 1989 in the vicinity of a manufacturing plant in Czechoslovakia that processes crude tar resulted in 6 of 8 samples containing dibenzofuran concns of 58.9 to 199.3 ng/cu m(2).

Listed as a hazardous air pollutant (HAP) generally known or suspected to cause serious health problems. The Clean Air Act, as amended in 1990, directs EPA to set standards requiring major sources to sharply reduce routine emissions of toxic pollutants. EPA is required to establish and phase in specific performance based standards for all air emission sources that emit one or more of the listed pollutants. Dibenzofuran is included on this list.

[40 CFR 302.4 (7/1/2001)] Persons in charge of vessels or facilities are required to notify the National Response Center (NRC) immediately, when there is a release of this designated hazardous substance, in an amount equal to or greater than its reportable quantity of 100 lb or 45.5 kg. The toll free number of the NRC is (800) 424-8802; In the Washington D.C. metropolitan area (202) 426-2675. The rule for determining when notification is required is stated in 40 CFR 302.4 (section IV. D.3.b).