The importance of particle weathering in micro and nanoplastic risk assessment, A review of the in vitro effects on the human digestive tract and immune system.

Abstract

Plastic waste has increased due to our extensive use of plastic products over the past 60 years. As this waste breaks down, it becomes tiny particles called microplastics (MPs). These MPs can be found in our environment, including in our food and water, which might pose health risks.When we consume these MPs, they travel through our digestive system and can potentially be absorbed by cells in our small intestine. Once inside our bodies, they come into contact with cells in our immune system around the intestines. Scientists have conducted studies using artificial models to understand the risks associated with MP exposure. However, there is a debate about which MPs to use in these studies. Some researchers use clean lab-bought particles known as virgin MPs, but these might not accurately represent the MPs in our environment. To address this, some studies have altered MPs to mimic real-world conditions, like movement or exposure to UV light. Different types of plastic have distinct properties, so they react differently to these alterations. In this review, researchers investigated how altering MPs in the lab affects their impact on cells in the intestines and immune system. They examined the chemical properties that affect the alteration of plastic and reviewed articles that studied the effects of altered and unaltered MPs on these cell models. The findings suggested that weathering, or altering, MPs can lead to different toxic effects compared to unaltered MPs. However, due to variations in exposure conditions, alteration methods, and cell models used in the studies, it is difficult to draw firm conclusions. Further large-scale and consistent research is needed, involving different types of plastic and alteration processes. This will help establish more reliable conclusions and increase our understanding of the effects of weathered MPs on our health.