A Critical Review of Contaminants of Emerging Concern in Reclaimed Wastewater: Implications for Agricultural Irrigation

Abstract

This critical review examines contaminants of emerging concern (CECs) in reclaimed wastewater used for agricultural irrigation, with a focus on their implications for environmental sustainability, food safety, and human and ecosystem health. Increasing water scarcity and climate change have intensified reliance on reclaimed wastewater, making a clear understanding of CEC behavior essential. Drivers of its use include technological advances, while barriers remain in the form of CEC occurrence, regulatory gaps, and public perception. The fate and transport of CECs in soil, water, and air determine their environmental risks. However, concentrations in treated wastewater from municipal/industrial wastewater treatment plants, desalination plant effluents, and others are typically low, with varying composition among similar wastewater. The incomplete removal causes leakage of CECs into reclaimed wastewater, thereby exhibiting persistence, bioaccumulation, and toxicity that can affect soil quality, plant physiology, and food safety. Plant uptake and long-term impacts depend on contaminant properties, irrigation practices, and crop species. Ecological risk assessments suggest moderate to high risks to aquatic organisms, while human health risks are generally low but may rise under worst-case exposure scenarios. Advanced treatment technologies, controlled irrigation, and soil management strategies can mitigate these risks by reducing bioavailability and enabling better monitoring. This review concludes with recommendations for researchers, practitioners, and policymakers to improve the safe and sustainable use of reclaimed wastewater in agriculture.