How Often do Plastic Constituents Find Their Way into Our Food?

Scientists from University Ss. Cyril and Methodium in Macedonia and the University of Porto in Portugal have authored a paper investigating plastic packaging constituents and their potential migration into packaged foodstuffs. Their research has been published in the journal Advances in Food and Nutrition Research.

Study: Occurrence of meso/micro/nano plastics and plastic additives in food from food packaging. Image Credit: SIVStockStudio/Shutterstock.com

Background to the Research

Since their invention in the mid-20th century, plastic products have become a ubiquitous part of the modern world. These incredibly useful products have rapidly replaced traditional packaging materials such as glass, paper, metal, and wood as they sufficiently meet all the mechanical and physiochemical specifications of packaging applications.

Plastics, which are either natural or synthetic polymers, have multiple beneficial characteristics which make them highly desirable materials for the packaging industry as well as several industrial sectors. Some of these characteristics include barrier properties, easy processibility, chemical inertness, cost-effectiveness, specific weight, transparency, and heat-sealing properties.

In 2020, global plastic production reached 367 million metric tons. In Europe alone, 8.2 million metric tons of plastics were used in food packaging. Thermoplastics such as polypropylene, low-density polyethylene, polyvinyl chloride, and polyethylene terephthalate are commonly used in the food packaging industry.

Whilst many polymers used in food packaging are considered food safe due to their lack of reactivity with food products, some lower-weight components used as coatings and additives can make their way into food which is then consumed by humans. For this reason, there are specific guidelines governing these components, and they must be approved before use by bodies such as the US FDA.

The Study

The new paper in the journal Advances in Food and Nutrition Research has reviewed several aspects of food packaging and routes by which packaging components can contaminate food products. Improving the knowledge of how this occurs and how legislation can play a part in reducing its impact leads to better health outcomes as some of these components may have unknown toxicity and therefore contribute to debilitating medical conditions in consumers.

Legislation

Legislation plays a key role in ensuring food safety, with a plethora of directives covering multiple aspects of the food industry, from animal husbandry, production, processing, packaging, transportation, storage, and retail, to end-user consumption and disposal. Public awareness of the side effects of plastic packaging has grown over the past few decades.

Several countries have their own sets of regulations, which various governmental bodies are responsible for implementing and enforcing. Several authorities and principles are recognized globally. Legislation and rules are not static; they constantly evolve in line with innovative technologies and practices in the food industry, and vice versa.

Plastic Material Migration

Migration is the mass transfer of plastic materials from packaging to food. Four steps are typically involved in migration: diffusion of chemical substances in the polymer, desorption from the surface of the polymeric material, sorption at the interface between packaging and food, and absorption into food.

Several types of migration have been identified, including contact migration, gas-phase migration, distillation/condensation migration, set-off migration, and penetration migration. Migration can be related to migrant numbers, food nature, and diffusion coefficients.

Phenomena and Factors Which Affect Migration

Migration is determined by several phenomena and factors. These are temperature, contact time, the packaging material, its properties, contact type (which can be direct or indirect), the initial concentration of the migrating compound, pH and the nature of the foodstuff, ratio of packaging surface area to food product volume, and the characteristics of the migrating product such as porosity and molecular size.

Types of Migrating Components

Multiple compounds which can potentially migrate into packaged foods have been identified by researchers. These include styrene monomers, Bisphenol A, vinyl chloride, PET oligomers, isocyanates, and caprolactam. Many of these compounds carry potential toxicity which is still not fully understood by researchers. For example, isocyanates possess potential carcinogenicity.

Different physical and physiochemical mechanisms govern the migration of different components, such as leaching, free radical scavenging, peroxide decomposition, decreasing viscosity, contact migration, desorption, condensation, and diffusion.

Many additives which are used to improve the properties and aesthetic appeal of plastic packaging contain substances that can migrate into food. These include lubricants, plasticizers, and additives that improve functionality such as antioxidative characteristics, fillers, nucleating agents, UV stabilizers, antistatic agents, and colorants.

In Summary

Innovations in the plastics industry have introduced novel materials over the past few decades which possess beneficial properties and characteristics, but the question of particle migration and potential harm to consumer health is a pressing concern. The ubiquity of plastic packaging and recognition of potential harm to consumers requires constant monitoring and legislation from governmental and international bodies.

By providing a timely review of factors that affect plastic component migration into food from packagings, such as legislation, component type, and factors and mechanisms which govern migration, the study provides valuable insights which will help ensure food safety for consumers.

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Further Reading

Nikova, E.V, Temkov, M & Rocha, J.M (2022) Occurrence of meso/micro/nano plastics and plastic additives in food from food packaging Advances in Food and Nutrition Research [online] sciencedirect.com. Available at: https://www.sciencedirect.com/science/article/abs/pii/S1043452622000675?via%3Dihub


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