Distribution, Sources and Health Risks of Polycyclic Aromatic Hydrocarbons (PAHs) in Household Dusts from Rural, Semi-urban and Urban Areas in the Niger Delta, Nigeria

Dusts from rural, semi-urban and urban areas of the Niger Delta, Nigeria were investigated for their polycyclic aromatic hydrocarbon (PAH) compositional patterns and sources, and risk of human exposure to PAHs in home dusts through non-dietary ingestion, inhalation and dermal contact pathways. The PAHs in the dust samples were extracted by ultra-sonication with hexane/dichloromethane and cleaned up on a silica gel/alumina column. The concentrations of the PAHs in the extracts were determined by gas chromatography–mass spectrometry. The Σ16 PAH concentrations in these household dusts varied from 60.0 to 1473, 124 to 2131 and 4531 to 111,914 µg kg−1 for the rural, semi-urban and urban areas, respectively. The characteristic PAH distribution pattern in the household dusts from urban areas followed the order: 4 > 6 > 5 > 3 > 2 rings, while in the semi-urban and rural areas, the distribution patterns followed the order: 3 > 6 > 4 > 5 > 2 rings and 5 > 6 > 4 > 3 > 2 rings, respectively. The benzo[a]pyrene carcinogenic potency concentration of PAHs in dusts from homes in these areas varied from 161 to 3288 µg kg−1, while the mutagenic potency concentration values varied between 154 and 3466 µg kg−1. The estimated lifetime cancer risk values arising from exposure to PAHs in dust in homes from rural, semi-urban and urban areas were larger than the target value of 10−6 (one chance in a million of equally exposed persons of the risk of suffering cancer or cancer-related diseases). Principal component analysis of the results suggested that the sources of PAHs in the dust from homes included cooking fuels and traffic emissions.