Bolded = in the Haz-Map database; See in Glossary
definitions of ACGIH, IARC,
and NTP carcinogens.
"Data are not sufficient to justify a numerical BEI scientifically,
based on health outcome or upon an airborne exposure (TLV). Therefore, the
"Nq" notation is recommended due to insufficient data to support a
numerical BEI." [ACGIH]
"PAHs are not currently produced for commercial use in the United
States. . . . PAHs do not usually enter the body through the skin under normal
conditions; however, small amount could enter the body if there is contact
with products or oils containing high concentrations of PAHs." [NTP]
PAHs are solids at room temperature. Approximately 100 compounds have been
identified. "Metabolism of PAHs occurs primarily (but not solely) in the liver by
the P450 mixed-function oxidase system. . . . Binding of PAH metabolites to
DNA is believed to be the mechanism of PAH-induced carcinogenesis. . . .
Skin-painting studies in a variety of animal models have demonstrated the
ability of benz[a]anthracene and indeno[1,2,3-c,d]pyrene to induce skin
tumors, and these therefore are considered to be complete carcinogens (both
initiators and promoters). Anthracene, fuoranthene, fluorene, phenanthrene,
and pyrene do not act as complete carcinogens." [Sullivan,
p. 1242-3
In addition to being carcinogenic and mutagenic, the PAHs have been found
to be potent immunosuppressants." [Klaassen,
p. 526]
Pyrene is not a carcinogen, but coal
tar pitch volatiles, a mixture of PAHs, are confirmed human carcinogens. [ACGIH]
"The carcinogenic potential of individual chemicals varies by many
orders of magnitude. PAHs almost always occur in mixtures; therefore the
carcinogenicity to humans cannot be linked to individual chemicals. . . . This
biomarker [1-HP] serves as an efficient complement to air-borne sampling,
because of the significant dermal absorption of these compounds." [Rosenstock,
p. 1059]
"The combustion process that release PAH invariably produce a variety
of compounds, and in fact, it is difficult or impossible to ascribe health
effects in humans to particular members of the PAH family. Hence, PAH are
usually treated as a group for the purpose of risk assessment." [Rom,
p. 1240]
"Several of the complex mixtures (coal tars and pitch, mineral oils,
shale oils, soots) that are classified as IARC group 1 carcinogens include
PAHs and several of the industries in which cancer risks have been identified
(e.g., coal gasification, coke production, aluminum production, iron and steel
founding) are industries in which PAHs are prevalent. Paradoxically, however,
there are no specific PAHs on the group 1 list. The highest classed PAHs are
in group 2A. . . . Because of the non-feasibility of measuring all PAHs when
they are measured for industrial hygiene purposes, there has typically been a
single marker of PAHs, often benzo(a)pyrene." [Schottenfeld, p.
334]
Polycyclic organic matter, or POM, as defined by the U.S. EPA in the
Federal Clean Air Act comprises a large and varied class of chemicals
compounds, including polycyclic aromatic hydrocarbons (PAH), and nitro-PAHs,
which are known carcinogens and mutagens. . . . Although the combustion of
fossil fuels is a ubiquitous source of POM in the urban ambient environment,
it is not the only source of human exposure to POM, and for some individuals
it may not be the predominant source. Other human exposure to POM comes from
inhaling wood and tobacco smoke, and from diet (e.g., from the consumption of
grilled meat). [Schottenfeld, p. 358]
Heterocyclic aromatic compounds (HACs) are "PAHs having any one carbon
atom in a ring replaced by a nitrogen, oxygen, or sulfur atom." [HSDB]