Toxicity Profiles
Condensed Toxicity Summary for DIBENZ[A,H]ANTHRACENE
NOTE: Although the toxicity values presented in these toxicity profiles were correct at the time they were produced, these values are subject to change. Users should always refer to the Toxicity Value Database for the current toxicity values.
Prepared for OAK RIDGE RESERVATION ENVIRONMENTAL RESTORATION PROGRAM
*Managed by Lockheed Martin Energy Systems, Inc., for the U.S. Department of Energy under
Contract No. DE-AC05-84OR21400
Dibenz[a,h]anthracene is a polycyclic aromatic hydrocarbon (PAH) with five aromatic rings.
No commercial production or use of dibenz[a,h]anthracene is known. It occurs as a component of
coal tars, shale oils, and soots (IARC, 1985) and has been detected in gasoline engine exhaust, coke
oven emissions, cigarette smoke, charcoal broiled meats, vegetation near heavily traveled roads, and
surface water and soils near hazardous waste sites (ATSDR, 1993; IARC, 1983).
Dibenz[a,h]anthracene is poorly absorbed from the gastrointestinal tract and is primarily
excreted via feces (Chang, 1943). Following absorption, dibenz[a,h]anthracene is distributed to
various tissues, with highest accumulation in the liver and kidneys (Daniel et al., 1967).
Dibenz[a,h]anthracene is metabolized by mixed function oxidases to dihydrodiols. Epoxidation of
the 3,4-dihydrodiol may lead to the formation of a diol-epoxide, the putative ultimate carcinogenic
metabolite of dibenz[a,h]anthracene (Buening et al., 1979).
No human studies were available to evaluate the toxicity of dibenz[a,h]anthracene. In animals,
depressed immune responses were observed in mice following single or multiple subcutaneous
injections of dibenz[a,h]anthracene (White et al., 1985). Weekly subcutaneous. injections of 0.05%
dibenz[a,h]anthracene for 40 weeks produced lymphoid tissue changes, decreased spleen weights,
and liver and kidney lesions in mice (Hoch-Ligeti, 1941). Weekly intramuscular injections of
20 mg/kg promoted the development of arteriosclerotic plaques in chickens (Penn and Snyder, 1988).
The EPA has not derived an oral reference dose (RfD) or inhalation reference concentration
(RfC) for dibenz[a,h]anthracene (EPA, 1995).
No epidemiologic studies or case reports addressing the carcinogenicity of
dibenz[a,h]anthracene in humans were available. In animals, dibenz[a,h]anthracene has produced
tumors by different routes of administration, having both local and systemic carcinogenic effects.
After oral administration, dibenz[a,h]anthracene produced tumors at several sites. Male and
female mice fed dibenz[a,h]anthracene (0.85 mg/day for males, 0.76 mg/day for females) in an
aqueous olive oil emulsion developed pulmonary adenomatosis, alveologenic carcinomas of the lung,
hemangio-endotheliomas of the pancreas and mesentery/abdominal lymph nodes, and mammary
carcinomas (females) after 200 days (Snell and Stewart, 1962). A single oral dose of 1.5 mg
dibenz[a,h]anthracene in polyethylene glycol produced a low incidence of forestomach papillomas
in mice (Berenblum and Haran, 1955). Mammary carcinomas developed in mice treated by gavage
with a total dose of 15 mg over a 15-week period (Biancifiori and Caschera, 1962).
Carcinogenic as well as tumor-initiating activity of dibenz[a,h]anthracene has been demonstrated
in topical application studies with mice. Repeated dermal application of 0.001 to 0.01% solutions
produced a high incidence of skin papillomas and carcinomas in mice (Wynder and Hoffmann, 1959;
Van Duuren et al., 1967). In initiation-promotion assays, the compound was active as an initiator of
skin carcinogenesis in mice (Buening et al., 1979; Platt et al., 1990). However, no skin tumors were
observed in Syrian golden hamsters that received topical dibenz[a,h]anthracene applications over
a 10-week period (Shubik et al., 1960).Injection site sarcomas developed in mice injected
subcutaneously with dibenz[a,h]anthracene (Pfeiffer, 1977). In newborn mice, a single subcutaneous
injection of dibenz[a,h]anthracene induced local sarcomas and lung adenomas (Platt et al., 1990) and
three intraperitoneal injections induced a high incidence of pulmonary tumors (Buening et al., 1979).
A number of earlier studies have also demonstrated the carcinogenicity of dibenz[a,h]anthracene
when administered by various parenteral routes in several animal species (IARC, 1973).
Based on no human data and sufficient evidence for carcinogenicity in animals, EPA has
assigned dibenz[a,h]anthracene a weight-of-evidence classification of B2, probable human
carcinogen (EPA, 1995).
Last Updated 10/07/97
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