Micro- and nanoplastics – current state of knowledge with the focus on oral uptake and toxicity
Catégorie : Impacts de la Pollution
Date :17 décembre 2020
Avis TSC : There is a real buzz of publications on microplastics that are found everywhere and that we have been ingesting or inhaling for decades. The precaution principle raises questions about their direct or indirect toxicity. This article, written by scientists from ANSES and its German equivalent, provides an overview of knowledge in this field. Their conclusion is the following: « In summary, risk assessment of micro- and nanoplastics is still not possible, due to various data gaps in terms of exposure, biodistribution and related effects » The lack of standardization of analytical methods and reference materials are all shortcomings that prevent comparison of the results of different studies. This does not induce the safety of MPs, but risks discussed in many publications remain potential risks for the time being.
The production and use of plastics has constantly increased over the last 30 years. Over one third of the plastics is used in disposables, which are discarded within three years of their production. Despite efforts towards recycling, a substantial volume of debris has accumulated in the environment and is slowly degraded to micro- and nanoplastics by weathering and aging. It has recently been discovered that these small particles can enter the food chain, as for example demonstrated by the detection of microplastic particles in honey, beer, salt, sea food and recently in mineral water. Human exposure has further been documented by the detection of plastic microparticles in human feces. Potential toxic consequences of oral exposure to small plastic particles are discussed. Due to lacking data concerning exposure, biodistribution and related effects, the risk assessment of micro- and nanoplastics is still not possible. This review focuses on the oral uptake of plastic and polymer micro- and nanoparticles. Oral exposure, particle fate, changes of particle properties during ingestion and gastrointestinal digestion, and uptake and transport at the intestinal epithelium are reviewed in detail. Moreover, the interaction with intestinal and liver cells and possibly resulting toxicity are highlighted.