Cancer risk assessment, indicators, and guidelines for polycyclic aromatic hydrocarbons in the ambient air.

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are formed during incomplete combustion. Domestic wood burning and road traffic are the major sources of PAHs in Sweden. In Stockholm, the sum of 14 different PAHs is 100-200 ng/m(3) at the street-level site, the most abundant being phenanthrene. Benzo[a]pyrene (B[a]P) varies between 1 and 2 ng/m(3). Exposure to PAH-containing substances increases the risk of cancer in humans. The carcinogenicity of PAHs is associated with the complexity of the molecule, i.e., increasing number of benzenoid rings, and with metabolic activation to reactive diol epoxide intermediates and their subsequent covalent binding to critical targets in DNA. B[a]P is the main indicator of carcinogenic PAHs. Fluoranthene is an important volatile PAH because it occurs at high concentrations in ambient air and because it is an experimental carcinogen in certain test systems. Thus, fluoranthene is suggested as a complementary indicator to B[a]P. The most carcinogenic PAH identified, dibenzo[a,l]pyrene, is also suggested as an indicator, although it occurs at very low concentrations. Quantitative cancer risk estimates of PAHs as air pollutants are very uncertain because of the lack of useful, good-quality data. According to the World Health Organization Air Quality Guidelines for Europe, the unit risk is 9 X 10(-5) per ng/m(3) of B[a]P as indicator of the total PAH content, namely, lifetime exposure to 0.1 ng/m(3) would theoretically lead to one extra cancer case in 100,000 exposed individuals. This concentration of 0.1 ng/m(3) of B[a]P is suggested as a health-based guideline. Because the carcinogenic potency of fluoranthene has been estimated to be approximately 20 times less than that of B[a]P, a tentative guideline value of 2 ng/m(3) is suggested for fluoranthene. Other significant PAHs are phenanthrene, methylated phenanthrenes/anthracenes and pyrene (high air concentrations), and large-molecule PAHs such as dibenz[a,h]anthracene, benzo[b]fluoranthene, benzo[k]fluoranthene, and indeno[1,2,3-cd]pyrene (high carcinogenicity). Additional source-specific indicators are benzo[ghi]perylene for gasoline vehicles, retene for wood combustion, and dibenzothiophene and benzonaphthothiophene for sulfur-containing fuels.

Exposure of HepG2 cells to low levels of PAH‐containing extracts from contaminated soils results in unpredictable genotoxic stress responses

“…Some PAHs are genotoxic and bind to DNA, while others have tumor promoting effects [Boström et al, 2002]. In this study, we showed that soil fractions from industrially contaminated sites, containing complex mixtures of PAHs and related compounds (e.g., oxy-PAHs), exhibited soilspecific patterns of DNA damage signaling proteins and exhibited signs of interactions between different PAHs.…”

“…Benzo [a]pyrene is often used as an indicator of carcinogenic PAHs in complex mixtures [Boström et al, 2002]. However, animal studies have shown that the BP indicator may reflect as little as 20% of the cancer potency of such mixtures, and may thus underestimate the risk [Gaylor et al, 2000].…”

“…Cdk2 used as loading control. [Boström et al, 2002]. Toxic equivalents quota (TEQ) calculated using the toxic equivalency factors (TEFs) established by Larsen and Larsen, 1998.…”

Genotoxic effects of three selected black toner powders and their dimethyl sulfoxide extracts in cultured human epithelial A549 lung cells in vitro

“…PAH bind to cytosolic receptors and may therefore affect cell growth and differentiation [Bayram et al, 1998]. Some PAHs are human mutagens and carcinogens [Bostrom et al, 2002]. Since PAHs occurred in all three toner-powder samples (Table II), we conclude that these compounds are responsible for the genotoxic effects determined by the comet and CB-MNvit assays.…”

Personal exposures and indoor, residential outdoor, and urban background levels of fine particle trace elements in the general population

“…Particulate organic compounds and chiefly polycyclic aromatic hydrocarbons (PAHs) are produced by incomplete combustion processes and some of those are known carcinogenic species, while others are suspected of being carcinogenic (Bostrom et al, 2002). Another group that has gained interest in recent years is metals.…”