Environmental and human health risk assessments of polycyclic aromatic hydrocarbons in particulate matter in Nigeria

Polycyclic aromatic hydrocarbons (PAHs) are an important organic group in particulate matter which has attracted much attention among the scientific community in terms of health risk because of their carcinogenic, mutagenic, and ubiquitous nature in the environment. In this study, PAHs in particulate matter in Okitipupa were determined. Indoor and outdoor particle samples were sampled with the aid of SKC Air Check XR5000 high-volume gravimetric sampler, and analyzed using gas chromatography flame ionization detector (GC-FID). The results obtained showed that high molecular weight PAHs (5-ring, 6-ring PAHs) had higher mean concentration than low molecular weight PAHs (2-ring, 3-ring PAHs), in both indoor and outdoor particulate matter. Health risk assessments from exposure to these PAHs were also determined using toxicity equivalence quotient (TEQ), mutagenicity equivalence quotient (MEQ), incremental life cancer risk (ILCR), and hazard quotient (HQ). Dibenz(a,h)anthracene had the highest mean concentration across the sample location in both indoor and outdoor with values ranging from 33 to 31 and 90 to 93 µg/m3 respectively. The total mean concentration in outdoor PAHs ranged from 280 to 329 µg/m3, while total mean concentration in indoor PAHs ranged from 74 to 104 µg/m3. The incremental lifetime cancer risk in indoor ranged from 6.9 × 10–7 to 1.2 × 10–5, while the ILCR in outdoor ranged from 8.5 × 10–6 to 1.0 × 10–5. The hazard quotient in indoor ranged from 7.6 × 10–5 to 2.2 × 10–3, while the HQ in outdoor ranged from 10 × 10–4 to 1.4 × 10–3. These values are within the WHO permissible limit, and therefore underscores the danger associated with the inhalation of polycyclic aromatic hydrocarbons in Okitipupa.