Urinary PAHs metabolites in Karakoram Highway's heavy traffic vehicle (HTV) drivers: evidence of exposure and health risk

The current study features PAHs exposure on Karakoram Highway, a route of utmost importance in Pakistan. The drivers of heavy traffic vehicles (HTV) on Karakoram Highway spend long hours amid dense traffic and therefore, inevitably inhale huge amount of PAH carcinogens. The urinary metabolites of PAHs in such drivers (meeting selection criteria n = 48) and a control group (n = 49) were comparatively profiled. The higher urinary biomarkers among ninety-six percent HTV drivers were evident of PAHs exposure. We observed elevated concentrations of urinary benzo[a]pyrene metabolites (3-OH-BaP = 3.53 +/- 0.62 ng g(-1) creatinine and 9-OH-BaP = 3.69 +/- 0.74 ng g(-1) creatinine) in HTV driver's samples compared to controls (0.85 +/- 0.08 and 0.31 +/- 0.03 ng g(-1) creatinine, respectively). Interestingly, urinary benzo[a]pyrene metabolites were detected in almost similar amount among HTV drivers irrespective of their working hours. A distinct smoking effect was manifested with rising urinary levels of 1-hydroxypyrene, 2-hydroxyphenanthrene, and 3-hydroxybenzo[a]pyrene with corresponding increase in driving hours per day. These metabolites exhibited characteristic exposures to low molecular weight volatile PAHs that are commonly found in vehicular exhaust. The elevated PAH body burden was directly linked to the nature of their job and the route-long environmental pollution on Karakoram Highway. Additionally, the poor economic status and smoking also increased HTV driver's health vulnerability and significantly declined their health capacity. There was conclusive evidence that HTV drivers were exposed to PAHs during a ride on Karakoram Highway, back and forth, an aspect not reported earlier.

Automated summary

This study investigated the exposure to PAHs on the Karakoram Highway in Pakistan. Results showed that HTV drivers who spent long hours in heavy traffic inhaled a significant amount of PAH carcinogens. The urinary metabolites of PAHs were higher in HTV drivers compared to the control group. Urinary benzo[a]pyrene metabolites were detected in similar amounts among HTV drivers regardless of their working hours. The study also found a smoking effect on urinary levels of certain metabolites, which were associated with the increase in driving hours per day. The elevated PAH body burden was linked to the nature of the drivers' job and the environmental pollution on the Karakoram Highway.