Chapter 23 - Epilogue: Summary, the next-frontier emerging contaminants/novel entities, and a look ahead

Abstract

The present book applied a number of conceptual frameworks to discuss emerging contaminants, and their health risks and mitigation. Four groups of emerging contaminants were discussed: (1) synthetic organic chemicals, (2) high-technology rare earth elements, (3) microplastics, and (4) antibiotic/antimicrobial resistance. This chapter presents an epilogue and outlook for the book, and acts as a sign-post to guide future research efforts on emerging contaminants. A summary of the state-of-the-art on emerging contaminants and the contribution of each chapter/section is presented. An increasing body of evidence exists on the four groups of emerging contaminants covered in the present book. This subset of emerging contaminants can be considered as the ‘back-end’ cluster, whilst a new subset of relatively less studied emerging contaminants also known as novel entities constitutes the 'front-end' or next-frontier emerging contaminants. A discussion of the next-frontier emerging contaminants or novel entities/technologies, including prions, engineered bio-based material, blockchain, nanotechnology, and gene editing/CRISPR (clustered regularly interspaced short palindromic repeats) is presented. The outbreak of the COVID-19 pandemic towards the end of 2019 changed the complexion of emerging contaminants in terms of the nature, concentrations, and potential impacts. These COVID-19-induced complexities, including a summary of the available evidence and future directions are highlighted. Finally, grand challenges or higher-order research questions on emerging contaminants are highlighted to guide further research.