Distribution and Health Risk Assessment of Polycyclic Aromatic Hydrocarbons (PAH) in Indoor Dust from Warri Metropolis, Nigeria.

Abstract:

Indoor dust acts as a sink for polycyclic aromatic hydrocarbons (PAHs), which predominantly originate from the incomplete combustion of organic matter. In this study, sixteen priority PAHs were quantified in dust samples collected from twenty residential and commercial sites across Warri Metropolis, Nigeria. Analysis by gas chromatography–mass spectrometry (GCMS) revealed that total PAH concentrations (∑PAHs) averaged 310880 ± 32440 µg/kg⁻¹, with five-ring (12015 ± 35480 µg/kg⁻¹) and six-ring (96160 ± 30590 µg/kg⁻¹). Incremental lifetime cancer risk (ILCR) calculations showed that dermal (6.18 × 10⁻¹) and ingestion (3.23 × 10⁻¹) exposures far exceeded the U.S. EPA’s acceptable risk range of 1 × 10⁻⁶ to 1 × 10⁻⁴, whereas inhalation risk remained negligible (2.48 × 10⁻¹¹). Hazard Quotient (HQ) analysis indicated that key carcinogens—Benzo[a]pyrene (HQₜᵢₙg = 3.20; HQₜₑᵣₘ = 3.00) and Dibenzo[a,h]anthracene (HQₜᵢₙg = 3.00; HQₜₑᵣₘ = 3.10)—surpassed the safety threshold of 1. Indoor dust BaP concentrations far exceeded European soil target values (100 µg kg⁻¹), underscoring elevated exposure risks. These findings highlight an urgent need for enhanced indoor air quality management, targeted reduction of combustion emissions, and public health interventions to mitigate PAH exposure in urban Nigerian settings. Continuous monitoring and large-scale epidemiological studies are recommended to elucidate long-term health outcomes in susceptible populations.