Micro- and nano-plastic contamination in foods and potential risk to human health.

The ubiquitous presence of micro- and nano-plastics (MNPs) has made their pollution a global concern, as it leads to human exposure. Dietary exposure represents a major route for human exposure to MNPs, which have the potential to impact human health. This paper aims to review the source, occurrence, characteristics, and analytical methods of MNPs in food. The challenges and limitations involved in assessing the human health risks associated with MNPs through food consumption were also discussed. Studies have found that various foods, particularly seafood, are contaminated with MPs. However, limited data are available on MPs in other commonly consumed food items such as meat, vegetables, and fruits. Furthermore, there is a lack of investigation into the characteristics of nanoplastics (NPs, <1 µm) and oligomer polymers (low molecular weight polymers) which are more prone to entering human body because of smaller sizes. MNPs are possibly introduced into food through different pathways, including raw food materials, food processing and production, packaging and containers, as well as preparation and dining processes. The complexity of food matrix poses challenges to the development of methodologies to investigate MNPs, hindering comprehensive data acquisition and human exposure assessment. Additionally, the lack of epidemiological, clinical, and toxicological data related to environmental MNPs makes it difficult to conduct accurate hazard identification and characterization. These limitations impede the feasibility of conducting health risk assessment. Therefore, we urgently call for a better understanding of health risks of MNPs, achieved through the improvement of methodologies and the expansion of available data.