Toxicity Profiles

RAGs A Format for Benz[a]anthracene - CAS Number 56553

Benz[a]anthracene is a polycyclic aromatic hydrocarbon (PAH) containing four aromatic rings two of which share carbons with only one other ring. It is soluble in alcohol, ether and benzene but practically insoluble in water. There is no commercial application for benz[a]anthracene, however, it is a ubiquitous contaminant formed during the incomplete combustion of organic material. Benz[a]anthracene is found in various kinds of smoke and flue gases, tobacco smoke, automobile exhaust, roasted coffee and in charcoal broiled, barbecued or smoked meats. It is also found in creosote, coal tar, petroleum asphalt, and a variety of foods, including vegetable oils and baker's yeast. It is an atmospheric contaminant near power plants and busy highways, and tends to bind to particulate matter in the atmosphere. In general, there is a region in the structure of PAH's that is known to react with DNA, which may account for both their toxicity and carcinogenicity.

The toxic effects of benz[a]anthracene and similar PAHs are primarily directed toward tissues that contain proliferating cells. Animal studies indicate that exposure to PAH's with distinct chemical structure can damage the hematopoietic system leading to progressive anemia as well as agranulocytosis. The lymphoid system can also be affected resulting in lymphopenia. Toxic effects have been observed in the rapidly dividing cells of the intestinal epithelium, spermatogonia and resting spermatocytes in the testis and primary oocytes of the ovary. Most of these effects have occurred following both oral and parenteral exposure. Epithelial proliferation and cell hyperplasia in the respiratory tract have been reported following subchronic inhalation exposure.

The primary concern with benz[a]anthracene exposure is its potential carcinogenicity. There is no unequivocal, direct evidence of the carcinogenicity of the compound to humans, however, benz[a]anthracene and other known carcinogenic PAHs are components of coal tar, soot, coke oven emissions and tobacco smoke. There is adequate evidence of its carcinogenic properties in animals. Oral exposures of mice to benz[a]anthracene have resulted in hepatomas, pulmonary adenomas and forestomach papillomas. The EPA weight-of-evidence classification is: B2, probable human carcinogen, for both oral and inhalation exposure based on adequate animal evidence and no human evidence.

The following is a presentation of the toxicity information associated with Benz[a]anthracene:

• The Oral Slope Factor is 7.30E-01 (mg/kg-day)^-1.

• The Inhalation Unit Risk is 8.8E-02 (mg/m^3)^-1.

• The Dermal Slope Factor is 2.35E+00 (mg/kg-day)^-1.
• The Dermal Slope Factor is based on a gastrointestinal absorption factor of 0.3100.