Microplastic contamination of packaged meat: Occurrence and associated risks

https://doi.org/10.1016/j.fpsl.2020.100489Get rights and content

Highlights

  • Sub-millimetre-sized particles are observed on packed poultry meat.

  • The particles revealed by FTIR analysis are of the same chemical nature as the extruded polystyrene packaging.

  • These microplastics are likely to come from the XPS trays.

Abstract

Food trays are often made from extruded polystyrene (XPS), and quantities of millimetre-sized particles of this material are trapped between the meat they contain and the sealing film. The purpose of this study is to identify the chemical nature of these particles and quantify them. Furthermore, the quantification of synthetic or organic fibres was also carried out. The results show that XPS microplastics (MP-XPS) contaminate food products at a level ranging from 4.0 to 18.7 MP-XPS/kg of packaged meat. Analysis shows that these microplastics are likely to come from the XPS trays. These particles are difficult to remove by mere rinsing and are probably cooked before being consumed. However, at this stage, it is not clear from the scientific literature whether there is a potential risk to humans associated with the ingestion of MP-XPS. In addition to these MP-XPS, it should also be pointed out that fibres can also contaminate meat.

Introduction

Between 1950 and 2015, 7800 million tons of plastic were produced, half of which between 2002 and 2015 Geyer, Jambeck, & Law, 2017). The physical properties of plastic materials make them essential in industrialized societies. In Europe, the packaging, construction, and automotive sectors account for nearly 70 % of the demand for plastic, with nearly 40 % for packaging alone (PlasticsEurope, 2018). In the food sector, the use of plastic packaging helps in the storage, transport, protection, and preservation of products while reducing their waste (Lange & Wyser, 2003; Mathlouthi, 2013; Piringer & Baner, 2008; PlasticsEurope, 2012). Because some plastics such as expanded polystyrene (EPS) or extruded polystyrene (XPS) provide a good protection barrier from oxygen, water vapour, and microorganisms, they facilitate the preservation of food products at a desired temperature; hence, they are widely used in food packaging. However, it has been recently reported that packaging may release plastic particles and subsequently contaminate our food with plastic fragments (Oßmann et al., 2018; Schymanski, Goldbeck, Humpf, & Fürst, 2018; Winkler et al., 2019).

The presence of small plastic particles in the natural environment has been known since the early 1970s (Buchanan, 1971), but it is only in the early 2010s that their presence in food was reported (Barboza, Dick Vethaak, Lavorante, Lundebye, & Guilhermino, 2018). Among these, microplastics, namely plastic particles smaller than 5 mm in size (GESAMP, 2019), were found. In 2013, a study carried out on honey and sugar coming from different countries revealed contamination by fibres and fragments (Liebezeit & Liebezeit, 2013). Although no chemical analysis was performed to assess the chemical nature of these particles, a connection was established between the morphology of these fragments and the plastic bags used by beekeepers to supply sugar to bees. In 2014, the identification of microplastics in mussels (Mytilus edulis) grown for human consumption suggests that humans ingest these particles (Van Cauwenberghe & Janssen, 2014). To date, several studies have reported the presence of plastic particles in seafood and fish for human consumption (Azevedo-Santos et al., 2019; Barboza & Gimenez, 2015). Microplastics have also been observed in salt (Gündoğdu, 2018; Iñiguez, Conesa, & Fullana, 2017; Karami et al., 2017; Yang et al., 2015), in beers (Kosuth, Mason, & Wattenberg, 2018; Liebezeit & Liebezeit, 2014), and in water bottles (Mason, Welch, & Neratko, 2018). These microplastics, generally smaller than 100 μm, probably come partly from the packaging and/or bottling process (Mason et al., 2018). A large-scale study of tap water showed that 81 % of the water sampled was contaminated mainly by fibres of which an unknown part is of synthetic origin (Kosuth et al., 2018). Fibres can be defined as particles of equal thickness along their entire length, the difference between artificial and natural fibres being based on the presence or absence of visible cellular or organic structures (Hidalgo-Ruz, Gutow, Thompson, & Thiel, 2012). For the purposes of this publication, no distinction will be made between artificial and natural fibres. The origin of the fibres observed in food is not always clear, but airborne contamination is often thought of. The atmosphere is an important vector of microplastics, as shown by the atmospheric deposition of synthetic fibres in Paris (Boucher & Friot, 2017; Dris, Gasperi, Saad, Mirande, & Tassin, 2016). These fibres are also omnipresent in our indoor environment to the point of posing a significant risk of contamination of samples (Dehaut, Hermabessiere, & Duflos, 2019). It is commonly accepted that synthetic textiles are the main source of these fibres (Boucher & Friot, 2017; Prata, 2018).

This study is part of the OceanWise project, a European project supported by the European funding program INTERREG Atlantic Area. OceanWise aims to jointly develop a set of long-term measures to reduce the impact of expanded and extruded polystyrene (EPS/XPS) products in the North-East Atlantic Ocean. Some economic activities, which generate EPS/XPS waste, are particularly investigated in the OceanWise project: the fishing industry (fisheries, aquaculture, sea-food), the food industry (supermarket chains, distribution of vegetables, fish, meat, fruit), consumer goods, outdoor festivals, and tourism. In this context, several observations of more or less free sub-millimetre particles inside food packaging with an XPS bottom containing meat were made during a preliminary study for the OceanWise project tests. These microparticles have the same colour as the XPS food packaging that contained them. Faced with these elements, it was therefore decided to verify the following hypotheses: Are these particles microplastics of extruded polystyrene (MP-XPS)? What is the estimated mass of MP-XPS per mass of meat? How many fibres are present on the surface and inside the food packaging? In an attempt to determine the origin of the particles and fibres as well as the timing of the deposition, the distribution of MP-XPS was studied inside and outside the tray. Thus, this preliminary study, limited to the case of France, seeks to answer these questions and identify some elements of discussion regarding the possible origins of these particles, as well as the possible consequences of ingesting them for human health.

Section snippets

Sample collection and preparation

This study focuses on meat products (chicken) packed in extruded polystyrene trays (230 × 140 × 20 mm). The mass of the pieces of meat was determined by reading the mass displayed on the label on the plastic packaging. Samples of meat from brands B, C, D had a roughly equivalent mass (on average close to 250 g), while brand A meat samples were slightly larger in mass (about 315 g) (Table 1). Products from four different brands (named A, B, C, and D) were purchased in a local supermarket (n = 3

Particles

The characteristics of the microparticles were the same as those of the XPS tray: presence of vacuoles, identical colour, and identical chemical nature. There is therefore no doubt that they came from the tray. FTIR spectra and the microscopic observations of the collected particles showed the presence of MP-XPS microparticles inside the packaging as well as on its outer surface. It should also be noted that some MP-XPS were found between the meat and the plastic seal (Fig. 1). The MP-XPS

Sources of MP-XPS

To our knowledge, this study is the first one to draw attention to the microplastics found on the surface of meat products sealed in their packaging. This contamination necessarily raises the question of the origin of the microplastics. The observation of the presence of MP-XPS inside and outside the tray, as well as between the tray and the meat, and between the meat and the protective film, leads to the hypothesis that the deposition of particles starts before the meat was deposited and lasts

Conclusion

Only few scientific studies report the presence of microplastics that contaminate food. Our study, by assessing the presence of microplastics on the surface of meat products, extends the state of knowledge on the contamination of human food by microplastics. These microplastics are highly adherent to the meat surface and are likely to be eaten by consumers. Although polystyrene trays are made of polystyrene suitable for food contact, the presence of MP-XPS on the food surface is potentially

CRediT authorship contribution statement

Mikaël Kedzierski: Conceptualization, Methodology, Formal analysis, Supervision, Writing - original draft, Writing - review & editing. Benjamin Lechat: Validation, Investigation, Data curation. Olivier Sire: Methodology, Supervision, Writing - review & editing. Gwénaël Le Maguer: Project administration, Writing - review & editing. Véronique Le Tilly: Methodology, Supervision, Writing - review & editing. Stéphane Bruzaud: Supervision, Funding acquisition, Writing - review & editing.

Acknowledgement

The authors are grateful to the OceanWise project that made this publication possible. OceanWise is funded by the European Regional Development Fund (ERDF) INTERREG Atlantic Area, under Priority Axis 4: Enhancing biodiversity and the natural and cultural assets.

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