Abstract
Dust deposited on leaves of trees can be effectively used as monitors of polycyclic aromatic hydrocarbons (PAHs). Sixteen EPA priority PAHs concentrations in deposited dust on leaves of the street trees (leaves dust) at 14 sampling sites at traffic and residential areas in Cairo, Egypt were measured. The health risk of the 16 PAHs to humans were estimated and calculated. Results indicate that the predominant PAHs were high molecular weight-PAHs, with higher contribution 83%, whereas low molecular weight-PAHs were the less lower contribution 17%. Higher concentrations of sigma PAHs recorded at traffic areas (18,223 +/- 4,172) mg/kg, whereas lower levels were found in residential areas (8,261 +/- 2,006) mg/kg. The diagnostic ratios and total indexes of PAHs compounds indicate that traffic emissions and incomplete combustion were the major sources of PAHs in deposited dusts on leaves of street trees of Greater Cairo. The health risk assessment focused on sigma PAHs in leave dust, which were related to health impacts. The results recorded higher exposure doses at traffic areas than residential areas. In the current study, hazard quotient and hazard indices values were less than 1 at all sampling sites, indicating that there were no health effects for noncarcinogen. The cancer risk values for inhalation of PAHs in traffic areas > residential areas for child and adult. The current results showed that the cancer risk values were within the safe levels set by United States Environmental Protection Agency. These results indicate that cancer risk values for Greater Cairo were within the acceptable range, implying negligible carcinogenic risk.