Polycyclic aromatic hydrocarbons (PAHs) in street dust of Rio de Janeiro and Niterói, Brazil: Particle size distribution, sources and cancer risk assessment

- Polycyclic aromatic hydrocarbons (PAHs) were studied in 2 fractions of street dust
- Samples were collected in selected areas of Rio de Janeiro and Niteroi, Brazil
- Comparable PAH concentrations were found in similar areas of both cities
- Vehicular emissions were shown to be the major PAH source to the samples
- Residential areas showed a cancer risk around 10− 5 due to PAH concentrations

Fifteen polycyclic aromatic hydrocarbons (PAHs) were analyzed in two fractions (< 63 μm and 63-850 μm) of street dust samples collected in different urban areas of Rio de Janeiro and Niterói cities, Brazil. Individual PAH concentrations and total PAH concentrations (∑ PAH) were evaluated considering geographic and particle size distributions, PAH source and cancer risk. In 53% of the samples, ∑ PAH values were higher in the smallest particles than in the largest ones, whereas the inverse was true for 23.5% of the samples. In 23.5% of the samples, both classes of particles showed comparable ∑ PAH. The highest ∑ PAH concentrations were found in areas of limited air dispersion, resulting in PAH accumulation in street dust. The diagnostic ratios and principal component analysis (PCA) indicated a strong influence of pyrogenic sources on PAH concentration, mainly of vehicular emissions. The cancer risk levels for children and adults, for both particulate size fractions (< 63 μm and 63 μm-850 μm), were comparable for dermal contact and by ingestion, and ranged from 10− 8 to 10− 6, whereas in certain cases the cancer risk level for adults by dermal contact was 2 to 3 times larger than for children. The cancer risk levels via inhalation always ranged from 10− 13 to 10− 10, so this exposure pathway was almost 104 less severe than through ingestion and dermal contact, and thus negligible.

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