Do 16 Polycyclic Aromatic Hydrocarbons Represent PAH Air Toxicity?

Area of Science:

• Environmental Chemistry
• Air Quality Science
• Toxicology

Background:

• The U.S. Environmental Protection Agency (EPA) prioritizes 16 polycyclic aromatic hydrocarbons (PAHs) for air quality management.
• Current monitoring often overlooks gas-phase PAHs, focusing primarily on particle-bound compounds.
• This focus may lead to an underestimation of the total health risks associated with atmospheric PAH mixtures.

Purpose of the Study:

• To evaluate if the 16 EPA-priority particle-bound PAHs adequately represent the health risks of inhalation exposure to complex atmospheric PAH mixtures.
• To compare the carcinogenic potency of the 16 EPA PAHs with the total toxicity of 88 PAHs, including gas-phase components.

Main Methods:

• Analysis of 88 PAHs in both gas and particle phases from 13 diverse air sampling projects.
• Utilized the toxic equivalency factor (TEF) approach to convert PAH concentrations to benzo(a)pyrene-equivalent (BaPeq) toxicities.
• Estimated TEFs for compounds lacking data using those of similar isomers.

Main Results:

• The 16 EPA particle-bound PAHs underrepresented the total carcinogenic potency by an average of 85.6% compared to the 88 PAHs analyzed.
• Gas-phase PAHs, such as methylnaphthalenes, can contribute significantly, up to 30% of the total BaPeq toxicity.
• Non-priority PAHs and gas-phase PAHs are crucial for accurate risk assessment.

Conclusions:

• The standard assessment using only 16 particle-bound EPA PAHs is insufficient for accurately evaluating inhalation health risks.
• Incorporating gas-phase and other non-priority PAHs is essential for a comprehensive and accurate risk assessment of air samples.
• Future air quality management strategies should consider a broader spectrum of PAHs for improved public health protection.