Distribution, sources and risk of exposure to polycyclic aromatic hydrocarbons in indoor dusts from electronic repair workshops in southern Nigeria

This study evaluates the characteristic levels, sources and risk of human exposure to polycyclic aromatic hydrocarbons (PAHs) in indoor dusts from electronic repair workshops in southern Nigeria. The dust samples were collected by gentle sweeping with a brush and dustpan, and subsequently dried and extracted with hexane/dichloromethane by ultrasonication. The extracts were purified on a silica gel/alumina column, and then analysed for their PAH content by means of gas chromatography-mass spectrometry. The concentrations of PAHs in the electronic repair workshop dusts ranged between 205 and 2963 μg kg−1. The compositional patterns indicate the dominance of 5- and 3-ring PAH homologues. The estimated benzo[a]pyrene carcinogenic (BaPTEQ) and mutagenic (BaPMEQ) potency concentrations ranged from 67 to 401 μg kg−1 and 56.5–277 μg kg−1 respectively. The non-cancer risk (hazard index, HI) arising from human contact with PAHs in the electronic repair workshop dusts were less than one for all human subject age groups indicating that there is no considerable non-cancer risk. The cancer risk values for the ingestion and dermal contact routes were greater than the acceptable risk of 10−6, which suggests that there is a considerable cancer risk associated with unconscious ingestion and dermal contact with dust particles from these electronic repair workshops. The isomeric ratios for the PAHs in the dust samples and principal component analysis suggest that combustion of biomass and vehicular emissions were responsible for the presence of PAHs in the electronic repair workshop dusts.