Multi-Media Exposure to Polycyclic Aromatic Hydrocarbons at Lake Chaohu, the Fifth Largest Fresh Water Lake in China: Residual Levels, Sources and Carcinogenic Risk

Abstract

The residual levels of 16 priority polycyclic aromatic hydrocarbons (PAHs) in environment media and freshwater fish were collected and measured from Lake Chaohu by using Gas chromatography-mass spectrometry. Potential atmospheric sources were identified by molecular diagnostic ratios and the positive matrix factorization (PMF) method. PAH exposure doses through inhalation, intake of water and freshwater fish ingestion were estimated by the assessment model recommended by US EPA. The carcinogenic risks of PAH exposure were evaluated by probabilistic risk assessment and Monte Carlo simulation. The following results were obtained: (1) The PAH₁₆ levels in gaseous, particulate phase, water and fish muscles were 59.4 ng·m⁻³, 14.2 ng·m⁻³, 170 ng·L⁻¹ and 114 ng·g⁻¹, respectively. No significant urban-rural difference was found between two sampling sites except gaseous BaP_eq. The relationship between gaseous PAHs and PAH in water was detected by the application of Spearman correlation analysis. (2) Three potential sources were identified by the PMF model. The sources from biomass combustions, coal combustion and vehicle emission accounted for 43.6%, 30.6% and 25.8% of the total PAHs, respectively. (3) Fish intake has the highest lifetime average daily dose (LADD) of 3.01 × 10⁻⁶ mg·kg⁻¹·d⁻¹, followed by the particle inhalation with LADD of 2.94 × 10⁻⁶ mg·kg⁻¹·d⁻¹. (4) As a result of probabilistic cancer risk assessment, the median ILCRs were 3.1 × 10⁻⁵ to 3.3 × 10⁻⁵ in urban and rural residents, which were lower than the suggested serious level but higher than the acceptable level. In summary, the result suggests that potential carcinogenic risk exists among residents around Lake Chaohu. Fish ingestion and inhalation are two major PAH exposure pathways.