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| | Benzo[a]pyrene Chemical Properties |
| Melting point | 177-180°C | | Boiling point | 495°C | | density | 1.1549 (estimate) | | vapor pressure | 2.4 at 25 °C (McVeety and Hites, 1988) | | refractive index | 1.8530 (estimate) | | Fp | 495°C | | storage temp. | 2-8°C | | solubility | Soluble in benzene, toluene, and xylene; sparingly soluble in ethanol and methanol (Windholz et
al., 1983) | | pka | >15 (Christensen et al., 1975) | | form | Crystalline | | color | Pale yellow/green/orange | | Water Solubility | Soluble in benzene, toluene, and xylene. Sparingly soluble in alcohol, methanol. Insoluble in water | | Merck | 14,1103 | | BRN | 1911333 | | Henry's Law Constant | 7.35 at 25 °C (thermodynamic method-GC/UV spectrophotometry, Altschuh et al., 1999)(x 10-10 mmHg at 25 °C): | | Exposure limits | OSHA: TWA 0.2 mg/m3 | | Stability: | Stable. Incompatible with strong oxidizing agents. | | InChIKey | FMMWHPNWAFZXNH-UHFFFAOYSA-N | | CAS DataBase Reference | 50-32-8(CAS DataBase Reference) | | IARC | 1 (Vol. Sup 7, 92, 100F) 2012 | | EPA Substance Registry System | Benzo[a]pyrene (50-32-8) |
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| English |
| | Benzo[a]pyrene Usage And Synthesis |
| Description | Benzo[a]pyrene belongs to the class of polycyclic aromatic hydrocarbons (PAHs). It is produced during incomplete combustion or pyrolysis of organic material and found in nature from the eruption of volcanoes and forest fires. Man-made benzo[a]pyrene is formed by burning plants, wood, coal, and operating cars, trucks and other vehicles. It is also present in some foods (e.g. smoked and barbecued meals), in a few pharmaceutical products, and in tobacco smoke. It is considered as potent mutagen and carcinogen. Benzo[a]pyrene containing extender oil is used for the rubber/plastic production to achieve the desired elasticity at a cheaper price. Benzo[a]pyrene containing coal tar pitch is used in many paints or coatings as corrosion protection coats, such as hydraulic equipment, pipework, steel pilings in ports, vessels, and sealcoat products. Benzo[a]pyrene can be used as wood-preservatives to prevent wood parasites and the wood from drying out.
| | References |
- https://monographs.iarc.fr/ENG/Monographs/vol100F/mono100F-14.pdf
- http://www.dhss.delaware.gov/dph/files/benzopyrenefaq.pdf
- https://greenliving.epa.gov.tw
- https://www.umweltbundesamt.de
- Barbara J. Mahler, Peter C. Van Metre, Judy L. Crane, Alison W. Watts, Mateo Scoggins, and E. Spencer Williams, Coal-Tar-Based Pavement Sealcoat and PAHs: Implications for the Environment, Human Health, and Stormwater Management, Environ Sci Technol, 2012, vol. 46, 3039-3045
| | Description | Benzo(a)pyrene (BaP) is bioactivated to its carcinogenic form
by phase 1 and phase 2 metabolism. As with other polycyclic
aromatic hydrocarbons (PAHs), the presence of the ‘bay
region’ contributes greatly to the carcinogenicity of BaP. This
region is sterically constrained, allowing the formation of
diol epoxides, which subsequently react with intracellular
molecules such as DNA. Human exposure to BaP and other
PAHs occurs primarily from smoking or from secondhand
smoke, air polluted with combustion products, or food and
water polluted with combustion products, such as those
cooked over charcoal or broiled.
BaP has been extensively studied for its toxicities in children
and during pregnancy. A study of pregnant active smokers
showed that BaP crossed the human placenta and was bound
to fetal hemoglobin at levels significantly higher than in pregnant
nonsmokers. | | Chemical Properties | B(a)P, is yellowish needles, crystals or powder.
Odorless. PAHs are compounds containing multiple benzene
rings and are also called polynuclear aromatic
hydrocarbons. | | Physical properties | Odorless, yellow, orthorhombic or monoclinic crystals from ethanol. Solution in concentrated
sulfuric acid is orange-red and fluoresces green under exposure to UV light (quoted, Keith and
Walters, 1992). | | Uses | Benzopyrene is a polyaromatic hydrocarbon (PAH) found in coal tar. Benzopyrene is a known carcinogen. The metbolism of Benzopyrene results in diol epoxides that react and bind to DNA forming adducts which in turns leads to mutations and eventually cancer. | | Uses | BaP is not commercially produced; it is a by-product of
combustion. Its primary uses include toxicological mechanistic
studies and cancer studies, as a positive control in carcinogenicity
studies. There is no known commercial use for BaP. | | Uses | Extensively used in cancer research and for GC (Gas Chromatography) and LC (Liquid Chromatography) Analysis. It is also a multipurpose intermediate. | | Definition | ChEBI: An ortho- and peri-fused polycyclic arene consisting of five fused benzene rings. | | Definition | A cyclic aromatic hydrocarbon
with a structure consisting of five fused
benzene rings. It occurs in coal tar and tobacco
smoke and has strong carcinogenic
properties. | | General Description | A liquid. Presents a threat to the environment. Immediate steps should be taken to limits its spread to the environment. Easily penetrates the soil and contaminates groundwater or nearby waterways. | | Air & Water Reactions | Insoluble in water. | | Reactivity Profile | BENZO[A]PYRENE undergoes photo-oxidation after irradiation in indoor sunlight or by fluorescent light in organic solvents. Incompatible with strong oxidizing agents including various electrophiles, peroxides, nitrogen oxides and sulfur oxides. Oxidized by ozone, chromic acid and chlorinating agents. Readily undergoes nitration and halogenation. Hydrogenation occurs with platinum oxide . | | Hazard | Highly toxic, confirmed carcinogen by inhalation. | | Health Hazard | The acute oral toxicity of benzo[a]pyrene islow. This may be due to the poor absorption of this compound by the gastrointestinal tract.The lethal dose in mice from intraperitonealadministration is reported as 500 mg/kg(NIOSH 1986).
Animal studies show sufficient evidence ofits carcinogenicity by all routes of exposureaffecting a variety of tissues, which includethe lungs, skin, liver, kidney, and blood.
Dasenbrock et al. (1996) have investigatedthe carcinogenic potency of carbon particles,diesel soot and benzo[a]pyrene in rats fromrepeated intracheal administration in a 16-week study. A total dose of 15 mg purebenzo[a]pyrene caused lung tumor in theexperimental animals at a rate similar tothat caused by diesel soot and carbon blackparticles.
Lodovici et al. (1998) measured the levelsof PAHs and benzo[a]pyrenediol epoxideDNA adduct in autoptic lung samples ofsmokers and non-smokers. Benzo[a]pyrenediol epoxide resulting from metabolic activation of benzo[a]pyrene binds to DNA to forman adduct, the levels of which can be used as abiomarker to evaluate the exposure of humansto benzo(a)pyrene.
Benz[a]pyrene exhibited teratogeniceffects in test species. It is a mutagen.It showed positive in a histidine rever-sion–Ames test, cell transform mouse embryotest, and in in vitro sister chromatid exchange(SCE)–human lymphocytes.. | | Fire Hazard | Literature sources indicate that BENZO[A]PYRENE is nonflammable. | | Toxicology | benzo[a]pyrene (BP) is a reasonably potent contact carcinogen, and therefore has been subjected
to extensive carcinogenic testing. A diet containing 25 ppm of benzo[a]pyrene (BP) fed to
mice for 140 days produced leukemia and lung adenomas in addition to
stomach tumors. Skin tumors developed in over 60% of the rats treated topically
with approximately 10 mg of benzo[a]pyrene three times per week.
The incidence of skin tumors dropped to about 20% when treatment was
about 3 mg 3 per week. Above the 10 mg range, however, the incidence
of skin tumors increased dramatically to nearly 100%.
benzo[a]pyrene (BP) is also carcinogenic when administered orally. In one experiment,
weekly doses of greater than 10 mg administered for 10 weeks induced
stomach cancers, although no stomach cancers were produced at the dose
of 10 mg or less. At 100 mg doses, nearly 79% of the animals had developed
stomach tumors by the completion of the experiment.
When 15 ppm of benzo[a]pyrene (BP) in feed was orally administered to mice, production of
leukemia, lung adenomas, and stomach tumors were observed after 140 days. | | Safety Profile | Confirmed carcinogen withexperimental carcinogenic, neoplastigenic, andtumorigenic data. A poison via subcutaneous,intraperitoneal, and intrarenal routes. Experimentalteratogenic and reproductive effects. Human mutation data reported. A skin irritant. | | Potential Exposure | Benzopyrene (BP) is a PAH that
has no commercial-scale production. B(a)P is produced in
the United States by one chemical company and distributed
by several specialty chemical companies in quantities from
100 mg to 5 g for research purposes. Although not manufactured
in great quantity, B(a)P is a by-product of
combustion. It is estimated that 1.8 million pounds per year
are released from stationary sources, with 96% coming
from: (1) coal refuse piles, outcrops, and abandoned coal
mines; (2) residential external combustion of bituminous
coal; (3) coke manufacture; and (4) residential external
combustion of anthracite coal. Human exposure to B(a)P
can occur from its presence as a by-product of chemical
production. The number of persons exposed is not known.
Persons working at airports in tarring operations; refuse
incinerator operations; power plants, and coke manufacturers,
may be exposed to higher B(a)P levels than the general
population. Scientists involved in cancer research or in
sampling toxic materials may also be occupationally
exposed. The general population may be exposed to B(a)P
from air pollution, cigarette smoke, and food sources. B(a)
P has been detected in cigarette smoke at levels ranging
from 0.2 to 12.2:g per 100 cigarettes. B(a)P has been
detected at low levels in foods ranging from 0.1 to 50 ppb. | | Source | MCLG: zero; MCL: 0.2 μg/L (U.S. EPA, 2000).
Identified in Kuwait and South Louisiana crude oils at concentrations of 2.8 and 0.75
ppm, respectively (Pancirov and Brown, 1975). Emitted to the environment from coke production,
coal refuse and forest fires, motor vehicle exhaust, and heat and power (utility) generation (Suess,
1976). Benzo[a]pyrene is produced from combustion of tobacco and fuels. It is also a component
of gasoline (133–143 μg/L), fresh motor oil (20 to 100 g/kg), used motor oil (83.2 to 242.4
mg/kg), asphalt (≤0.0027 wt %), coal tar pitch (≤1.25 wt %), cigarette smoke (25 μg/1,000
cigarettes), and gasoline exhaust (quoted, Verschueren, 1983). Detected in asphalt fumes at an
average concentration of 14.72 ng/m3 (Wang et al., 2001). Benzo[a]pyrene was also detected in
liquid paraffin at an average concentration of 25 μg/kg (Nakagawa et al., 1978).
Benzo[a]pyrene was reported in a variety of foodstuffs including raw and cooked meat (ND to
12 ppb), fish (0.3–6.9 ppb), vegetables oils (ND-4), fruits (ND to 6.2 ppb) (quoted, Verschueren,
1983).
The concentration of benzo[a]pyrene in coal tar and the maximum concentration reported in
groundwater at a mid-Atlantic coal tar site were 3,600 and 0.0058 mg/L, respectively (Mackay and
Gschwend, 2001). Based on laboratory analysis of 7 coal tar samples, benzo[a]pyrene
concentrations ranged from 500 to 6,400 ppm (EPRI, 1990). In three high-temperature coal tars,
benzo[a]pyrene concentrations ranged from 5,300 to 7,600 mg/kg (Lehmann et al., 1984).
Benzo[a]pyrene was identified in a U.S. commercial creosote at an approximate concentration
of 0.3% (Black, 1982). Nine commercially available creosote samples contained benzo[a]pyrene
at concentrations ranging from 2 to 160 mg/kg (Kohler et al., 2000).
Identified in high-temperature coal tar pitches used in roofing operations at concentrations
ranging from 4,290 to 13,200 mg/kg (Arrendale and Rogers, 1981; Malaiyandi et al., 1982). Lee et
al. (1992a) equilibrated 8 coal tars with distilled water at 25 °C. The maximum concentration of
benzo[a]pyrene observed in the aqueous phase was 1 μg/L.
Schauer et al. (2001) measured organic compound emission rates for volatile organic
compounds, gas-phase semi-volatile organic compounds, and particle phase organic compounds
from the residential (fireplace) combustion of pine, oak, and eucalyptus. The particle-phase
emission rates of benzo[a]pyrene were 0.712 mg/kg of pine burned, 0.245 mg/kg of oak burned,
and 0.301 mg/kg of eucalyptus burned.
Particle-phase tailpipe emission rates from gasoline-powered automobiles with and without
catalytic converters were 0.021 and 41.0 μg/km, respectively (Schauer et al., 2002).
Under atmospheric conditions, a low rank coal (0.5–1 mm particle size) from Spain was burned
in a fluidized bed reactor at seven different temperatures (50 °C increments) beginning at 650 °C.
The combustion experiment was also conducted at different amounts of excess oxygen (5 to 40%)
and different flow rates (700 to 1,100 L/h). At 20% excess oxygen and a flow rate of 860 L/h, the
amount of benzo[a]pyrene emitted ranged from 39.4 ng/kg at 650 °C to 690.7 ng/kg at 850 °C.
The greatest amount of PAHs emitted were observed at 750 °C (Mastral et al., 1999). | | Environmental fate | The main natural sources of Benzo[a]pyrene(BaP) are forest fires and erupting volcanoes. Anthropogenic sources include the combustion of fossil fuels, coke oven emis- sions, and vehicle exhausts. In surface waters, direct deposition from the atmosphere appears to be the major source of BaP. Benzo[a]pyrene is moderately persistent in the environment. It readily binds to soils and does not readily leach to groundwater, though it has been detected in some groundwater. If released to water, it sorbs very strongly to sediments and particulate matter. In most waters and sediments, it resists breakdown by microbes or reactive chemicals, but it may evaporate or be degraded by sunlight. In water supply systems, it tends to sorb to any particulate matter and be removed by filtration before reaching the tap. In tap water, its source is mainly from PAH-containing materials in water storage and distribution systems.
| | Purification Methods | A solution of 250mg of benzo[a]pyrene in 100mL of *benzene is diluted with an equal volume of hexane, then passed through a column of alumina, Ca(OH)2 and Celite (3:1:1). The adsorbed material is developed with a 2:3 *benzene/hexane mixture. (It showed as an intensely fluorescent zone.) The main zone is eluted with 3:1 acetone/EtOH, and is transferred into 1:1 *benzene-hexane by adding H2O. The solution is washed, dried with Na2SO4, evaporated and crystallised from *benzene by the addition of MeOH [Lijinsky & Zechmeister J Am Chem Soc 75 5495 1953]. Alternatively it can be chromatographed on activated alumina, eluted with a cyclohexane-*benzene mixture containing up to 8% *benzene, and the solvent evaporated under reduced pressure [Cahnmann Anal Chem 27 1235 1955], and crystallised from EtOH [Nithipatikom & McGown Anal Chem 58 3145 1986]. [Beilstein 5 III 2517, 5 IV 2687.] CARCINOGENIC. | | Toxicity evaluation | BaP is purposely synthesized solely for laboratory studies.
The primary source of BaP and many PAHs in air is the
incomplete combustion of wood, gasoline, and other fuels;
in industrial settings where coal is burned; and in natural
burns such as forest fires. BaP can bind to particulate matter,
and inhalation is a common route of exposure. BaP is poorly
water soluble, partitioning strongly to the sediment, and
does not readily bioaccumulate. BaP is found in fossil fuels,
crude oils, shale oils, and coal tars, and is emitted with gases
and fly ash from active volcanoes. If released to air, an
extrapolated vapor pressure of 5.49×10-9 mm Hg at 25°C
indicates BaP will exist solely in the particulate phase in the
atmosphere. Particulate-phase BaP is usually removed from
the atmosphere by wet or dry deposition. BaP contains
chromophores that absorb at wavelengths >290 nm and
therefore is expected to be susceptible to direct photolysis by
sunlight; after 17 h irradiation with light >290 nm, 26.5% of
BaP adsorbed onto silica gel was degraded. If released to soil,
BaP is expected to have very low to no mobility based on
measured soil Koc values of 930–6300. Volatilization from
moist soil surfaces is not expected to be an important
fate process based on a Henry’s Law constant of 4.57×10-7 atm m3 mol1. The stability of BaP in soil is
expected to vary depending on the nature of compounds
accompanying it and the nature and previous history of the
soil; biodegradation half-lives of 309 and 229 days were
observed in Kidman and McLaurin sandy loam soils,
respectively. BaP is expected to adsorb to suspended solids
and sediment based on the measured Koc values, when
released into water. Biodegradation of BaP is possible in
aquatic systems. Volatilization from water surfaces is not
expected to be an important fate process based on this
compound’s Henry’s Law constant. Measured bioconcentration
values ranging from 8.7 to 1×10105 suggest
bioconcentration in aquatic organisms can be low to very
high. Hydrolysis is not expected to be an important environmental
fate process since this compound lacks functional
groups that hydrolyze under environmental conditions. | | Incompatibilities | Incompatible with oxidizers (chlorates,
nitrates, peroxides, permanganates, perchlorates, chlorine,
bromine, fluorine, etc.); contact may cause fires or explosions.
Keep away from alkaline materials, strong bases,
strong acids, oxoacids, epoxides, nitrogen dioxide and ozone. | | Waste Disposal | Incineration in admixture
with a flammable solvent. |
| | Benzo[a]pyrene Preparation Products And Raw materials |
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![Benzo[a]pyrene Structure](CAS/GIF/50-32-8.gif)
