Evaluation of Polycyclic Aromatic Hydrocarbons as Emerging Pollutants in a Pharmaceutical Company at Eziama Aba, Nigeria

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are organic pollutants produced primarily through incomplete combustion of carbonaceous materials and are recognized as emerging environmental contaminants due to their mutagenic and carcinogenic properties. This study assessed the occurrence and distribution of sixteen priority PAHs in air, water, and soil matrices within and around pharmaceutical industries in Eziama Community, Aba, Abia State, Nigeria. Systematic sampling was conducted at five strategic locations per site—upstream, downstream, outfall, residential, and background—to capture spatial variations. Extraction of PAHs was performed using solvent mixtures of ethanol, acetone, and hexane, followed by quantification via Gas Chromatography–Mass Spectrometry (GC–MS) in Selected Ion Monitoring (SIM) mode, with calibration curves exhibiting excellent linearity (R² > 0.98). Results indicated that total PAH concentrations followed the trend: soil (110.7 mg/kg) > air (48.3 µg/m³) > water (18.2 µg/L). Low molecular weight PAHs, such as naphthalene (air: 0.033 µg/m³; water: 0.056 µg/L; soil: 1.18 mg/kg) and phenanthrene (air: 0.103 µg/m³; water: 0.055 µg/L; soil: 1.31 mg/kg), predominated in air and water, reflecting volatility, solubility, and fresh inputs from effluents. High molecular weight PAHs, including pyrene (soil: 1.27 mg/kg) and benzo[a]pyrene (soil: 0.76 mg/kg; water: 0.026 µg/L; air: 0.058 µg/m³), accumulated mainly in soils, indicating chronic deposition and persistence due to hydrophobicity and low biodegradability. Diagnostic ratios (ANT/(ANT+PHE), FLT/(FLT+PYR)) suggested predominantly pyrogenic sources from industrial combustion, with additional contributions from solvent volatilization. Risk assessment revealed elevated BaP toxic equivalency (BaP-TEQ) in soil (0.96 mg/kg), air (0.37 µg/m³), and water (0.09 µg/L), exceeding regulatory limits and indicating potential long-term carcinogenic hazards. The findings underscore the significant contribution of pharmaceutical operations to environmental PAH contamination and highlight the necessity of effective remediation strategies such as microbial biostimulation, phytoremediation, and nano-zero valent iron (nZVI) application. These results provide critical baseline data for environmental management, policy formulation, and future studies on the fate, ecotoxicology, and mitigation of emerging pollutants in industrialized regions of the Niger Delta.