Comparative Carcinogenic Risk Assessment of Polycyclic Aromatic Hydrocarbons Accumulation in Normal and Cancerous Lung Tissues of Patients from Northern Thailand

Abstract

Lung cancer mortality is a critical issue in Northern Thailand, where incidence rates significantly exceed the national average. Key risk factors include tobacco smoking and seasonal air pollution from biomass burning, which releases carcinogenic polycyclic aromatic hydrocarbons (PAHs). This study aims to analyze the accumulation of 16 priority PAHs in human lung tissues to explore links between environmental exposure, smoking habits, and cancer development. Tissue samples (normal, para-cancerous, and adenocarcinoma) were collected from 30 surgical participants (15 lung cancer patients, 15 non-cancer controls) at Chiang Mai University Hospital. Compounds were extracted via ultrasonication and quantified using gas chromatography-mass spectrometry. Carcinogenic potency was evaluated using Benzo[a]pyrene equivalents, with concentrations compared across tissue types and patient groups using generalized estimating equations. High-molecular-weight PAHs were the dominant species, accounting for over 50% of total accumulation in all tissues, aligning with regional biomass burning profiles. Total concentrations and carcinogenic potency were significantly higher in smokers, particularly within normal lung tissues. Furthermore, high-molecular-weight PAH concentrations positively correlated with tissue cholesterol levels (R = 0.66). Source analysis indicated exposure primarily from pyrogenic sources, alongside petroleum emissions. In conclusion, high-molecular-weight carcinogens significantly accumulate in human lungs in Northern Thailand, reflecting substantial environmental exposure, while tissue lipid content modulates toxin bioaccumulation. Smoking facilitates compound retention in normal tissues, underscoring an urgent need for targeted public health strategies addressing both environmental pollution and tobacco use.