Microplastics in food
Microplastics (MPs) can get into foods through two main pathways, (1) from an organism collecting the particles from the environment while alive, e.g., filter feeding shrimp; or (2) from packaging or processing equipment.
To get a better understanding of human exposure to microplastics from foods, Emine Merve Canga and co-authors from University College Dublin reviewed research on microplastics in foods via both pathways. By analyzing the factors contributing to the wide range in numbers of reported particles, they hoped to elucidate inconsistencies in research methodology and provide recommendations to improve MP assessment.
Canga et al. found 67 studies fitting their search criteria which they broadly categorized by either food type: salt, seafood, honey, beer, produce, bottled waters; or by packaging type: takeaway containers, disposable cups, teabags, infant feeding bottles.
Of the four packaging types investigated, tea bags had by far the greatest discrepancy in reported particles. They explain, “[o]ne study reported that approximately 15 billion MPs were released into a cup of tea from a single teabag, whereas another research paper found only approximately 106.3 ± 14.6 MP/teabag after brewing.” The authors propose that the difference in the tea bag studies could come from the polymers of the tea bags. The four studies all counted MPs in the same size range but some used nylon while others had PET or did not report what their teabags were made from. Additionally, “properties of teabag brands, and the features of the production processes might lead to inconsistent outcomes.”
Other differences in testing procedure across the different packaging types were investigated including sample preparation, e.g., hot versus cold water to induce MP release; filter properties, “the importance of using appropriate pore-sized filters, which would not cause overlooking of smaller MPs as well as clogging, was very clear… the pore size of the filter and the range of the detected particle size should be given in detail”; and detection and analytical methods, e.g., reporting mass of MPs versus number of particles.
“[T]o understand the effects of MPs ingested with food and beverages on human health, the consumption of MPs must be accurately determined.” While seemingly obvious, the study of microplastics is still in its infancy, lacking standards on study procedure and reporting. The authors suggest establishing methods for each matrix – whether food or packaging. Pre-treatments with alcohol may help prevent the measurement of non-plastic polymers.
Regulatory needs
Timothy Duncan and three co-authors from the US Food and Drug Administration express many of the same concerns as Canga et al. in their review of MNPs in foods. However, they then highlight what the research field needs to standardize to be helpful to regulators. Published on March 7, 2024, in the journal Analytical Chemistry, Duncan et al. outline the needs for standardized procedures for methodology and MP prevalence, much the same as Canga et al., but also outline toxicity, and mitigation needs. They write that, overall, the micro and nanoplastics research community needs to:
- “delineate minimum data needs to support exposure assessments that can be used to determine potential impacts to health impact (e.g., mass concentrations classified by size and polymer type, with uncertainty values);
- set data reporting and metrological interoperability standards, including MP and NP [nanoplastic] measurement units and precisions relevant to risk analysis;
- systematize basic methodological controls (reference materials, standards preparation, and sample handling/sanitation techniques) to ensure data reliability and interstudy consistency.”
Many people around the world are working on understanding the downstream effects of microplastics in the human body. 75 organizations from 21 countries have come together under five EU Horizon 2020 projects to form the European research cluster to understand the health impacts of micro- and nanoplastics, CUSP. Focusing in particular on exposure routes, hazard and risk assessment, and the development of new analytical tools to measure, characterize ,and quantify MNPs, the projects within CUSP are: AURORA, IMPTOX, Plastic Heal, PlasticsFatE, and POLYRISK. The Food Packaging Forum is one of 11 partners in the AURORA project, focusing on understanding the impacts of MNPs on early life health.
References
Canga, E.M., et al. (2024). “Assessing the inconsistency of microplastic measurements in foods and beverages.” Comprehensive Reviews in Food Science and Food Safety. DOI: 10.1111/1541-4337.13315
Duncan, T. et al. (2024). “Regulatory Science Perspective on the Analysis of Microplastics and Nanoplastics in Human Food.” Analytical Chemistry. DOI: 10.1021/acs.analchem.3c05408
Other recent studies on MNPs from packaging
Tavakolpournegari, A., et al. (2024). “Harmful effects of true-to-life nanoplastics derived from PET water bottles in human alveolar macrophages.” Environmental Pollution. DOI: 10.1016/j.envpol.2024.123823
Piyathilake, U., et al. (2024). “Exploring the hidden environmental pollution of microplastics derived from bioplastics: A review.” Chemosphere. DOI: 10.1016/j.chemosphere.2024.141773
