PAH intermediates: Links between the atmosphere and biological systems

Area of Science:

• Environmental Chemistry
• Atmospheric Science
• Toxicology

Background:

• China is the world's largest emitter of polycyclic aromatic hydrocarbons (PAHs).
• PAHs and their reactive intermediates undergo trans-Pacific atmospheric transport to the Western U.S.
• Understanding these transported pollutants is crucial for environmental and health assessments.

Purpose of the Study:

• To predict, identify, and quantify novel polycyclic aromatic hydrocarbon (PAH) intermediates.
• To investigate the atmospheric transport of PAHs from Asia to the Western U.S.
• To assess human exposure to PAH intermediates in both China and the U.S.

Main Methods:

• Computational methods (Gaussian) to predict thermodynamic properties of PAHs and their intermediates.
• Advanced analytical chemistry techniques to identify and quantify intermediates in atmospheric particulate matter.
• Field experiments in China and the U.S. to analyze PAH intermediates during transport and in source regions.
• Personal exposure studies in China and the U.S. to compare biological and atmospheric intermediates.

Main Results:

• Novel nitro-, oxy-, and hydroxy-PAH intermediates were predicted and identified.
• Quantification of PAH intermediates in Asian particulate matter before and after photochemical reactions.
• Analysis of the relative proportions of PAH intermediates in source regions versus during long-range transport.
• Comparison of atmospheric PAH intermediates with those found in biological samples from exposed populations.

Conclusions:

• This research provides critical insights into the nature and fate of atmospheric PAH intermediates.
• It highlights the trans-Pacific transport of these potentially harmful compounds.
• The findings contribute to a better understanding of human exposure and health risks associated with PAHs.