New contaminants: existence and knowledge gaps

Accelerating technological developments result in increasing emissions of a suite of elements and compounds that have received scant scientific attention.These "new contaminants" (NCs) have surged to the forefront of environmental research priorities.While lacking comprehensive regulation, NCs may be persistent, mobile, and bioaccumulative, posing substantial threats to both ecological security and public health.Their emergence underscores humanity's profound imprint on Earth's ecosystems as well as critical gaps in current scientific understanding.NCs derive from agriculture, household products, and high-tech industries, and often follow convoluted environmental pathways.Examples include pharmaceutical residues, microplastics, and electronic waste from manufacture through to recycling and disposal.New contaminants are broadly classified as: (a) chemical pollutants, including persistent organic pollutants, pharmaceuticals and personal care products, endocrine disruptors, disinfection by-products, and organometallics; (b) micro-and nanomaterials, such as microplastics and engineered nanoparticles; (c) biological contaminants, including antibiotic-resistant microorganisms, antibiotic resistance genes, pathogens, and viruses; and (d) other incompletely characterised substances.Though NCs may only be present at trace concentrations, they may bioaccumulate through food webs, show synergistic toxicity, disrupt endocrine and reproductive functions, and exacerbate antibiotic resistance.These effects threaten ecological and human health.Research on NCs has progressed from detection to characterisation and mitigation.Technological advances allow trace-level identification of previously undetectable compounds.This helps elucidate their sources, occurrence, and temporal trends.These findings demonstrate complex multimedia transport and transformation processes, leading to bioaccumulation across diverse biological taxa.Current research prioritises the identification of toxicological mechanisms.Integrating evidence from multi-omics, cellular assays, animal models, and epidemiological studies advances our understanding of the health impacts.Emerging cleanup technologies, such as advanced oxidation, membrane separation, engineered adsorption, and bioremediation, show potential in managing NCs.Efficient and sustainable remediation requires the integration of