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<p>Pharmaceutical effluents are emerging sources of persistent environmental contaminants, particularly in rapidly urbanizing regions such as Lagos, Nigeria. This study assessed the occurrence, distribution, and associated ecological and human health risks of polycyclic aromatic hydrocarbons (PAHs) and heavy metals (HMs) in wastewater discharged from four pharmaceutical manufacturing facilities located in different local government areas of Lagos State. Twenty effluent samples were collected over five consecutive days and composited by site for analysis. Physicochemical parameters were determined using standard methods, while PAHs and heavy metals were analysed using GC–FID and atomic absorption spectrophotometry (AAS), respectively. Results indicated that the wastewater was characterized by elevated organic load and low dissolved oxygen conditions, which are conducive to contaminant persistence. Total PAH concentrations showed marked spatial variation, with the highest level observed at MECUE (1.665&#xa0;mg/L), followed by PH (0.075&#xa0;mg/L) and JOPAN (0.019&#xa0;mg/L), while no PAHs were detected at NEROS. Heavy metals, including cadmium, manganese, zinc, nickel, and iron, were present at varying concentrations, with nickel and iron exceeding recommended guideline limits in most samples. Ecological risk indices indicated elevated contamination levels, particularly at MECUE, where pollution load index (PLI) and potential ecological risk index (PERI) values were highest. Human health risk assessment indicated that carcinogenic risks associated with PAHs and selected metals were within or near the acceptable USEPA threshold (10⁻⁶–10⁻<sup>4</sup>), with children showing higher susceptibility. Integrated analysis demonstrated that the co-occurrence and distribution of PAHs and heavy metals are influenced by shared sources and environmental conditions, including organic load, particulate content, and system dynamics that favour pollutant retention and reduced degradation. These interactions contribute to the formation of contamination hotspots and enhance ecological exposure risks. Overall, the findings highlight the need for improved wastewater treatment, continuous monitoring, and adoption of integrated assessment approaches to better understand and manage complex industrial effluent systems in developing regions.</p>

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Ecotoxicological Risks Associated with Recalcitrant Contaminants from Pharmaceutical Effluents in Selected Areas of Lagos, South-West Nigeria

  • 期刊论文

  • 发表日期：

    2026年8月1日

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  • Vincent Nwalieji Okafor,
  • Onyeka Fabian Obumselu,
  • James Chikelue Ozoemenam,
  • Daniel Omeodisemi Omokpariola,
  • Peter Obinna Okwuego,
  • Vivian Chisom Nwosu

摘要

Pharmaceutical effluents are emerging sources of persistent environmental contaminants, particularly in rapidly urbanizing regions such as Lagos, Nigeria. This study assessed the occurrence, distribution, and associated ecological and human health risks of polycyclic aromatic hydrocarbons (PAHs) and heavy metals (HMs) in wastewater discharged from four pharmaceutical manufacturing facilities located in different local government areas of Lagos State. Twenty effluent samples were collected over five consecutive days and composited by site for analysis. Physicochemical parameters were determined using standard methods, while PAHs and heavy metals were analysed using GC–FID and atomic absorption spectrophotometry (AAS), respectively. Results indicated that the wastewater was characterized by elevated organic load and low dissolved oxygen conditions, which are conducive to contaminant persistence. Total PAH concentrations showed marked spatial variation, with the highest level observed at MECUE (1.665 mg/L), followed by PH (0.075 mg/L) and JOPAN (0.019 mg/L), while no PAHs were detected at NEROS. Heavy metals, including cadmium, manganese, zinc, nickel, and iron, were present at varying concentrations, with nickel and iron exceeding recommended guideline limits in most samples. Ecological risk indices indicated elevated contamination levels, particularly at MECUE, where pollution load index (PLI) and potential ecological risk index (PERI) values were highest. Human health risk assessment indicated that carcinogenic risks associated with PAHs and selected metals were within or near the acceptable USEPA threshold (10⁻⁶–10⁻4), with children showing higher susceptibility. Integrated analysis demonstrated that the co-occurrence and distribution of PAHs and heavy metals are influenced by shared sources and environmental conditions, including organic load, particulate content, and system dynamics that favour pollutant retention and reduced degradation. These interactions contribute to the formation of contamination hotspots and enhance ecological exposure risks. Overall, the findings highlight the need for improved wastewater treatment, continuous monitoring, and adoption of integrated assessment approaches to better understand and manage complex industrial effluent systems in developing regions.