Environmental and health risks of nanowaste as an emerging contaminant: A systematic review

The huge production amounts and use of nanomaterials has led to the generation of an emerging type of waste stream that contains materials with nanoscale dimension and known as nanowaste. Once released into the environment, such waste can pose risks to the public health and environment. Due to their unique properties, the conventional risk assessment approaches cannot be adopted in nanowaste risk assessment, which is a serious challenge facing the regulatory process. This study conducted a systematic literature review to provide insight into the current scientific knowledge on nanowaste sources, release, pathways and the risks associated with their treatment and disposal. Data extracted from 37 articles that published during 2011–2023 was subjected to analysis following PRISMA statement. The results showed that there is an increasing trend in publications until the year 2018. Most of the published articles were from EU countries, where such articles stemmed from projects funded by the EC on Nano safety. Nanowaste may be released from point (single) and non-point (multiple) sources. Once released into the environment, nanowaste is subjected to partitioning and follow different pathways to environmental systems. The lack of regulatory requirements, standard characterization methodologies and the continuous production of new nanoproducts makes the quantification of the generated nanowaste a hard task. Such knowledge gaps increase the level of uncertainty in the risk assessment and leads to poor risk management and communication. This calls for the need in changes in the risk assessment framework of nanowaste to address their risk in a more systematic and accurate manner. Adopting stochastic modelling of the risk assessment parameters will lower the uncertainty levels.