Contamination levels, risks and sources of polycyclic aromatic hydrocarbons in current herbal formulations in Nigeria

Herbal formulations (HFs) are not properly regulated in Nigeria, and this is typical of several African countries. This is in addition to the lack of appropriate scientific/medical tests required for medications. Most producers/marketers lack evidence of the product's safety and effectiveness raising concerns on the overall safety of the HFs which are widely used across the country. This study therefore aimed to investigate the contamination levels, associated health risks and sources of polycyclic aromatic hydrocarbons (PAHs) in HFs sold in Bayelsa but produced across Nigeria. Fifty samples of the commonly known effective HFs were purchased from multiple locations and subjected to extraction using dichloromethane/n-hexane (1:1, v/v). Thereafter, the extracts were analysed using gas chromatograph-mass spectrometry. The contamination levels of the 16-USEPA PAHs varied between < LOQ and 1.67 µg kg−1. The 3-rings were the predominant PAHs in the HFs. The concentrations of benzo(a)pyrene (BaP) were below the European Commission allowable limit of 10 µg kg−1. The risk estimated using different models indicated the absence of health risk from consuming these HFs. The diagnostic ratios showed that the PAHs predominantly originated from pyrogenic sources. We recommend continuous monitoring and adequate regulations of PAHs and other hazardous pollutants in the HFs.