Differential Occupational Health Risks between Methylated PAHs and PAHs: Monitoring 126 PAHs and 6 Oxidative Stress Markers in Paired Serum-Urine Samples

The hazards of polycyclic aromatic hydrocarbons (PAHs) on occupationally exposed population have been widely acknowledged. However, the occupational exposure risks associated their derivatives, methylated PAHs, remain poorly understood. This study conducted a screen of 126 PAHs and 6 oxidative stress biomarkers (OSBs) in paired serum-urine samples from 110 petrochemical workers to assess the risk associated with different PAHs exposure. The results showed that the median concentrations of unmetabolized 16 priority PAHs (p-PAHs), 16 regular PAHs (R-PAHs), 50 methyl-PAHs (Me-PAHs), and 30 nitro-PAHs (N-PAHs) in serum (urine) were 97.98 (66.46), 11.02 (0.00), 77.76 (31.77), and 1.93 (0.10) ng/mL, respectively. The median concentration of metabolized hydroxy PAHs (OH-PAHs) in urine was 12.00 ng/mL (9.49 ng/mg creatinine). OSBs indicate that the hazards of Me-PAHs on exposed populations manifest as protein damage, while the hazards of p-PAHs mainly result in lipid and DNA damage. Results from common diseases and PAH exposure demonstrate a correlation between liver damage and PAH exposure, and Me-PAHs are more difficult to metabolize through urine due to their stronger lipophilicity. This study suggests that traditional health screenings targeting p-PAHs may be insufficient and likely underestimate the exposure risks for occupational populations.