Do 16 Polycyclic Aromatic Hydrocarbons Represent PAH Air Toxicity?

Abstract

Estimation of carcinogenic potency based on analysis of 16 polycyclic aromatic hydrocarbons (PAHs) ranked by U.S. Environmental Protection Agency (EPA) is the most popular approach within scientific and environmental air quality management communities. The majority of PAH monitoring projects have been focused on particle-bound PAHs, ignoring the contribution of gas-phase PAHs to the toxicity of PAH mixtures in air samples. In this study, we analyzed the results of 13 projects in which 88 PAHs in both gas and particle phases were collected from different sources (biomass burning, mining operation, and vehicle emissions), as well as in urban air. The aim was to investigate whether 16 particle-bound U.S. EPA priority PAHs adequately represented health risks of inhalation exposure to atmospheric PAH mixtures. PAH concentrations were converted to benzo(a)pyrene-equivalent (BaPeq) toxicity using the toxic equivalency factor (TEF) approach. TEFs of PAH compounds for which such data is not available were estimated using TEFs of close isomers. Total BaPeq toxicities (∑88BaPeq) of gas- and particle-phase PAHs were compared with BaPeq toxicities calculated for the 16 particle-phase EPA PAH (∑16EPABaPeq). The results showed that 16 EPA particle-bound PAHs underrepresented the carcinogenic potency on average by 85.6% relative to the total (gas and particle) BaPeq toxicity of 88 PAHs. Gas-phase PAHs, like methylnaphthalenes, may contribute up to 30% of ∑88BaPeq. Accounting for other individual non-EPA PAHs (i.e., benzo(e)pyrene) and gas-phase PAHs (i.e., naphthalene, 1- and 2-methylnaphthalene) will make the risk assessment of PAH-containing air samples significantly more accurate.

Carcinogenic Potency of Airborne Polycyclic Aromatic Hydrocarbons in Relation to the Particle Fraction Size

“…Total carcinogenic potencies observed by other authors at different locations worldwide are shown in Table 6 . However, the comparison of those results with this study is difficult due to the following reasons: PAHs were determined in different particle fractions or in both particle and gaseous phase; the number of PAHs investigated ranged considerably (for example, it amounted to eight in a study by Jung et al [ 49 ], and 88 in a study by Samburova et al [ 50 ]); different TEF schemes were used; different numbers of samples were collected with different distributions over the year. The TEFs by Nisbet and LaGoy [ 27 ] seem to be used the most often, although many authors used the modified version with a TEF value of 1.0 for DahA instead of 5.0.…”

“…Nitrated and oxygenated PAH compounds were not measured, which may have led to the underestimation of the full carcinogenic potential of PAH exposure. Samburova et al [ 50 ] analysed the results of 13 projects in which 88 PAHs were measured in both the gas and particle phase. They concluded that the gas phase might contribute up to 30% to the sum of 88 PAHs and 16 EPA particle bound PAHs represent only 14.4% of the total gas and particle carcinogenic potency.…”

Minimizing the Health Risks from Hydrocarbon Contaminated Soils by Using Electric Field-Based Treatment for Soil Remediation

“…The considered PAHs in the present work are naphthalene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benzo-a-anthracene, chrysene, benzo-b-fluoranthene, benzo-k-fluoranthene, benzo-a-pyrene, dibenzo-a, h-anthracene, benzo-ghi-perylene and indeno(1,2,3-cd)pyrene. These are found in the U.S. EPA list of 16 PAHs, issued by the U.S. Environmental Protection Agency (EPA, Washington, DC, USA) in 1976, known for their negative influence on humans [20,21].…”

Excitation-Emission Matrix Spectroscopy for Analysis of Chemical Composition of Combustion Generated Particulate Matter

“…15 The higher molecular weight compounds from this panel have been shown to have significant carcinogenic potential. 16 More recent reports 17 show larger MW PAH have high cancerogenic potential; thus in the current work, we extended the analysis to 24 PAHs, including PAHs up to MW=302 g/mol. In the analysis, we divided the PAHs into two categories: lower molecular weight (LMW) PAHs (MW=128-202 g/mol) and higher molecular weight (HMW) PAHs (MW=226-302 g/mol).…”