Polycyclic aromatic compounds in ambient PM2.5 in the Central Region of Ghana: Molecular distribution, origin and cancer risk assessment

The distribution, sources and the cancer risk of human exposure to PM2.5-bound polycyclic aromatic hydrocarbons (PAHs) were investigated in this work. Airborne particulate samples were obtained at the Winneba highway junction (WHJ) and Apam fish-smoking community (AFC) in the Central Region of Ghana from July 2022 to June 2023. PM2.5 particulates were collected using a Gent sampler equipped with a Gast pump and a stacked filter unit. 24-hour sampling was done two times a month using Teflon filters. Dichloromethane and gas chromatography with a mass spectrometer (GC-MS) were used to extract and analyse the samples, respectively, to identify 14 PAH compounds. The study discovered average PAH concentrations of 67.38 ng/m3 at WHJ and 41.59 ng/m3 at AFC. PAH profile was predominated with Phenanthrene, accounting for 25-27 % of total PAHs. The distribution pattern of PAHs was LMW>HMW>MMW at the two research sites. A strong correlation was found among BaA, BkF, BbF and BeP. The diagnostic ratio model revealed that PAHs stemmed from pyrogenic sources. The carcinogenic PAHs (BaP, BaA, Chr, BbF, BkF, BghiP) contributed approximately 90 % to the carcinogenic activity of total PAHs, denoting a high cancer potential of PAHs. The mean levels of BaP were about 8-10 times higher than the permissible limit of 1 ng/m3. The overall cancer risk values for exposure to PAHs via inhalation were more than 10-4, signifying high cancer risks: 11.61×10-4-21.14×10-4 for children and 19.91×10-4-36.24×10-4 for adults. Reducing PM2.5 and its health effects requires the use of clean fuel and the adoption of eco-friendly transportation