April 2022
What are microplastics?
Our society has become completely reliant on plastics [1]. Plastic is ubiquitous in our society from single use plastics such as drinking straws, plastic cutlery and fast food packaging, to plastics that are used in all parts of our lives, that have varying levels of durability and stability depending on their design and use. Plastics have been produced only over the last seventy years and in volume for the last half century. As plastics are designed to be chemically stable, they persist in the environment, are slow to degrade, but can be susceptible to ultraviolet sunlight or heat [2]. Microbes have been shown to have a role in degrading plastics in aquatic environments, but ironically this may increase the risk of microplastics being present in water [3]. This creates a contamination problem that can impact on our food supply chains and potentially public health.
Microplastics are small pieces of plastic, less than 5mm long [4] and can be so small we describe them as nanomaterials as their size is at the micron level, which means that they are barely visible. Microplastics are an unseen concern for most people, present in the natural environment, including in the air, soil and in water, and also from intentional and unintentional sources. they are found in food supply chains. Microplastics are either intentionally manufactured and added to a range of household, industrial and cosmetic products, or are unintentionally formed when large pieces of plastic fragment and break up during use, or disposal. The European Chemicals Agency (ECHA) explain that microplastics are ‘solid plastic particles composed of mixtures of polymers and functional additives’ [5]. Microplastics vary in their chemical composition, physical form (size and shape e.g. spheres, fibres) and texture [1]. They can be a carrier for toxic pollutants including heavy metals, polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and other contaminants such as personal care products or pharmaceuticals [2].
Microplastics have been found in marine, freshwater and terrestrial ecosystems in food and drinking water. The ECHA [5] state that:
- Around 42 000 tonnes of microplastics end up in the environment each year. The largest single source of pollution is the granular infill material used on artificial turf pitches (16 000 tonnes).
- The release of unintentionally formed microplastics is estimated to be around 176 000 tonnes a year into European surface waters. Some EU Member States have enacted or proposed national bans on intentional uses of microplastics in consumer products such as microbeads in cosmetics or microplastics used as abrasive and polishing agents.
Other sources can be paints, vehicle tyres, wastewater effluent, plastics used in agriculture, applications to soils and so on. Although some microorganisms can degrade plastics, generally once in the environment, microplastics do not biodegrade, so instead can accumulate in plants and in the digestive tracts [1] of animals, including wild fish [3,6] and shellfish, and as a result could be in food and water consumed by humans. They can also be present in the home or work environments from washing clothes, dust or as microfibres [7]. One study showed this potential for accumulation in soil (0.87 particles/g), earthworms (14.8 particles/g), and chicken faeces (130 particles/g) [8]. Marine animals have also been identified as suffering from accumulation of microplastics in their digestive tract and tissues [1]. Microplastics can affect soil organisms and plant growth, and digestion can cause mechanical damage, chemical responses and disrupt gut microbial communities [9]. Hence, the use of sewage sludge, as a soil amendment, is indeed a key source of microplastics in soil [10].
In one study, microplastic median intake rates were proposed to be between 553 particles/person/day (184 ng/day) for children and 883/particles/person/day (583 ng/day) for adults, where these particles are cumulative [11]. This can be through inhalation or ingestion. The continued release of microplastics contributes to permanent pollution of our ecosystems and food chains. Exposure to microplastics in laboratory studies has been linked to a range of negative (eco)toxic and physical effects on living organisms. There are two issues that need to be considered - the microplastics themselves and the chemicals that they may absorb before they are ingested. In 2016, the European Food Safety Authority (EFSA) assessed the available evidence on micro- and nano- plastics in food [12], concluding that more data was required on their occurrence and their potential effects on human health.
Analytical methods are now emerging to measure and detect microplastics in municipal water [13, 14], and soil and sheep faeces [15, 16], but this is at the academic research level rather than industry level. Academic research is determining methods for microplastic detection in fruits and vegetables [17] and some third-party laboratories are offering analysis services for presence of microplastics in bottled water, honey, salt and beverages. However, third party analysis is mainly focused on spectroscopy and the number of particles and particle size rather than more detailed chemical analysis.
This is difficult to determine as the range of microplastics is vast, as are their sources and composition. Also, microplastics are difficult to measure and detect from an on-line, real-time quality control perspective, due to their size, but also as they can be within a complex food matrix. Microplastics can be present in food packaging and materials, so identifying those of greatest concern is important [18]. Micron level filtration for microplastics in air and also in process water, where water is a major ingredient, is a control measure that should be considered, not only for microbiological controls but microplastic control too [13], Operational measures, in supply chains, currently focus on creating awareness and developing an evidence base from scientific and regulatory studies about microplastics. Industry level surveillance (verification), and monitoring techniques, need to be developed to identify the presence and quantity of microplastics in foods and beverages [1]. The pathways of transition from the environment to food also needs more study and consideration, so that the advice from regulators can be clear and form the basis of effective supply chain controls [1].
In conclusion, microplastics are an issue that will gain wider attention and the food supply chain, and business that operate within it, will need to have a greater evidence base on which to implement appropriate risk identification, assessment and management processes.
[1] Hale, R. C., Seeley, M. E., La Guardia, M. J., Mai, L., & Zeng, E. Y. (2020). A global perspective on microplastics. Journal of Geophysical Research: Oceans, 125(1), e2018JC014719. https://doi.org/10.1029/2018JC014719
[2] Wang, C., Zhao, J., & Xing, B. (2021). Environmental source, fate, and toxicity of microplastics. Journal of hazardous materials, 407, 124357. https://doi.org/10.1016/j.jhazmat.2020.124357
[3] Mallik, A., Xavier, K. M., Naidu, B. C., & Nayak, B. B. (2021). Ecotoxicological and physiological risks of microplastics on fish and their possible mitigation measures. Science of the Total Environment, 779, 146433. https://doi.org/10.1016/j.scitotenv.2021.146433
[4] NOS (nd). National Ocean Service. National Oceanic and Atmospheric Administration. US Department of Commerce. What are microplastics? Available at: https://oceanservice.noaa.gov/facts/microplastics.html
[5] ECHA (nd). European Chemicals Agency. Microplastics. Available at: https://echa.europa.eu/hot-topics/microplastics
[6] McIlwraith, H. K., Kim, J., Helm, P., Bhavsar, S. P., Metzger, J. S., & Rochman, C. M. (2021). Evidence of Microplastic Translocation in Wild-Caught Fish and Implications for Microplastic Accumulation Dynamics in Food Webs. Environmental Science & Technology, 55(18), 12372-12382. https://doi.org/10.1021/acs.est.1c02922
[7] Suzuki, G., Kida, A., Sakai, S., & Takigami, H. (2009). Existence state of bromine as an indicator of the source of brominated flame retardants in indoor dust. Environmental Science and Technology, 43, 1437–1442. https://doi.org/10.1021/es802599d
[8] Lwanga, E. H., Vega, J. M., Quej, V. K., Chi, J. A., Cid, L. S., Chi, C., et al. (2017). Field evidence for transfer of plastic debris along a terrestrial food chain. Scientific Reports, 7(1), 14,071–14,077. https://doi.org/10.1038/s41598‐017‐14588‐2
[9] Guo, J.J., Huang, X.P., Xiang, L., Wang, Y.Z., Li, Y.W., Li, H., Cai, Q.Y., Mo, C.H. & Wong, M.H., (2020). Source, migration and toxicology of microplastics in soil. Environment international, 137, p.105263. https://doi.org/10.1016/j.envint.2019.105263
[10] Corradini, F., Meza, P., Eguiluz, R., Casado, F., Huerta-Lwanga, E., & Geissen, V. (2019). Evidence of microplastic accumulation in agricultural soils from sewage sludge disposal. Science of the total environment, 671, 411-420. https://doi.org/10.1016/j.scitotenv.2019.03.368
[11] Mohamed Nor, N. H., Kooi, M., Diepens, N. J., & Koelmans, A. A. (2021). Lifetime accumulation of microplastic in children and adults. Environmental science & technology, 55(8), 5084-5096.https://doi.org/10.1021/acs.est.0c07384
[12] European Food Safety Authority (EFSA). (2016) Presence of microplastics and nanoplastics in food, with particular focus on seafood https://www.efsa.europa.eu/en/efsajournal/pub/4501
[13] Kirstein, I.V., Hensel, F., Gomiero, A., Iordachescu, L., Vianello, A., Wittgren, H.B. & Vollertsen, J., (2021). Drinking plastics?–Quantification and qualification of microplastics in drinking water distribution systems by µFTIR and Py-GCMS. Water research, 188, p.116519. https://doi.org/10.1016/j.watres.2020.116519
[14] Gomiero, A., Øysæd, K. B., Palmas, L., & Skogerbø, G. (2021). Application of GCMS-pyrolysis to estimate the levels of microplastics in a drinking water supply system. Journal of Hazardous Materials, 416, 125708. https://doi.org/10.1016/j.jhazmat.2021.125708
[15] Beriot, N., Peek, J., Zornoza, R., Geissen, V., & Lwanga, E. H. (2021). Low density-microplastics detected in sheep faeces and soil: A case study from the intensive vegetable farming in Southeast Spain. Science of the Total Environment, 755, 142653. https://doi.org/10.1016/j.scitotenv.2020.142653
[16] Fakour, H., Lo, S.L., Yoashi, N.T., Massao, A.M., Lema, N.N., Mkhontfo, F.B., Jomalema, P.C., Jumanne, N.S., Mbuya, B.H., Mtweve, J.T. and Imani, M., 2021. Quantification and analysis of microplastics in farmland soils: characterization, sources, and pathways. Agriculture, 11(4), p.330.https://doi.org/10.3390/agriculture11040330
[17] Conti, G.O., Ferrante, M., Banni, M., Favara, C., Nicolosi, I., Cristaldi, A., Fiore, M. and Zuccarello, P., 2020. Micro-and nano-plastics in edible fruit and vegetables. The first diet risks assessment for the general population. Environmental Research, 187, p.109677. https://doi.org/10.1016/j.envres.2020.109677
[18] Kumar, R., Sharma, P., Manna, C., & Jain, M. (2021). Abundance, interaction, ingestion, ecological concerns, and mitigation policies of microplastic pollution in riverine ecosystem: A review. Science of The Total Environment, 146695. https://doi.org/10.1016/j.scitotenv.2021.146695
Institute of Food Science & Technology has authorised the publication of the following Information Statement on Microplastics.
This Information Statement has been prepared by Professor Louise Manning RSci FIFST, peer-reviewed, and approved by the IFST Scientific Committee.
This information statement is dated April 2022.
The Institute takes every possible care in compiling, preparing and issuing the information contained in IFST Information Statements, but can accept no liability whatsoever in connection with them. Nothing in them should be construed as absolving anyone from complying with legal requirements. They are provided for general information and guidance and to express expert professional interpretation and opinion, on important food-related issues.