Contaminants of emerging concern in treated wastewater: a threat to sustainable agricultural reuse?

As global population growth intensifies the pressure on freshwater resources, the reuse of treated wastewater has emerged as a promising strategy for sustainable water management, particularly in the agriculture sector. However, this practice faces growing challenges due to the presence of contaminants of emerging concern (CECs), a diverse group of natural and anthropogenic substances that includes pharmaceuticals, personal care products, hormones, illicit drugs, pesticides, industrial chemicals, microplastics, and nanomaterials. Although often present at low concentrations, many of these compounds persist through conventional treatment processes, posing risks to both the environment and human health. This review critically examines the occurrence, classification, and variability of CECs in wastewater, emphasizing their fate and dynamics within the water–soil–plant system following the reuse of treated effluents in agricultural irrigation, and discussing their ecological and toxicological implications. It further highlights the urgent need for robust monitoring programs, refined risk-assessment methodologies, source-reduction strategies, and adaptive regulatory frameworks to effectively manage and mitigate the risks posed by trace levels of CECs in reclaimed wastewater used for food production. These measures aim to support the safe and sustainable reuse of treated wastewater in agriculture, ensuring long-term environmental integrity and public health protection.