Urinary metabolites of 1-nitropyrene in US-Mexico border residents who frequently cross the San Ysidro Port of Entry.

Diesel exhaust presents a community exposure hazard, but methods to measure internal exposure are lacking. We report results from a community-based study using 1-nitropyrene (1-NP) and its urinary metabolites as markers of exposure to traffic-related diesel particulate matter (DPM). The study participants were Tijuana, Mexico residents who commuted on foot into San Diego, California for work or school using the International San Ysidro Port of Entry, placing them within feet of idling traffic (referred to as border commuters).