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Category Products and chemicals

Ubiquitous and scientifically complex

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Copyright Person: JulPo, Confetti 1: Cineberg, Confetti 2: Liudmila Chernetska @gettyimages
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Microplastics are found in the environment, in food and even in the human body. To date, there is no evidence that they are harmful to health, but research is ongoing.

Microplastics are defined as plastic particles ranging in size from five millimetres (mmshort formillimetre) to one micrometre (μm). Even smaller fragments are referred to as nanoplastics. Microplastics are manufactured, for example, as plastic granules for further processing in industry, but also for applications such as infill material for artificial turfs. Microplastics form as a result of the breakdown of improperly disposed plastic waste, as well as through tyre wear. They can also be released from textiles made of synthetic fibres. Consequently, microplastics are found in water, soil and the air – and thus also in food.

“However, the mere detection of microplastics does not, in itself, indicate any health risk,” says Dr Holger Sieg. The biochemist heads a working group on microplastics at the German Federal Institute for Risk Assessment (BfRshort forGerman Federal Institute for Risk Assessment).

TOUCHING, BREATHING, EATING 

Humans come into contact with microplastics via the skin, breathing and diet, amongst other routes. Alongside air, dietary intake is considered the main source of exposure. However, just because microplastics enter the intestine does not mean that they are distributed throughout the body. According to current knowledge, only particles smaller than 1.5 μm (roughly the size of one-hundredth of a hair) can cross the intestinal barrier and enter the bloodstream; larger particles are excreted.

It is difficult to determine exactly what actual amount enters the body. The frequently cited figure of one credit card’s weight per week is based on flawed and oversimplified assumptions and is not scientifically suitable for representing actual intake levels. “It is assumed that significantly less is taken in, and the vast majority of it is excreted again,” explains Sieg. It has not yet been conclusively clarified how microplastics that remain in the body affect health. “At the BfRshort forGerman Federal Institute for Risk Assessment, we are conducting laboratory experiments to investigate whether microplastics bind to enzymes and thus influence their functions in metabolic processes.”

MICROPLASTICS IN THE BODY

Reports of microplastics in organs such as the brain are particularly worrying. Individual studies show that very small particles – particularly those on the nanoscale – can cross biological barriers. However, Dr Alexander Roloff, a scientist at the BfRshort forGerman Federal Institute for Risk Assessment specialising in the area of product analysis, points out “that the detection of such particles is methodologically very challenging and results must be interpreted with caution”. It is very difficult to rule out the possibility that microplastics entered the samples during sampling or preparation – for example, via plastic materials used in the laboratory. Consequently, it is often unclear whether the organ samples were contaminated with microplastics from the environment. Process controls, i.e. the inclusion of a microplastic-free control sample during analysis, are essential. “Analytical methods for microplastics are still prone to error and imprecise,” says Roloff. Reliably measuring microplastics in organs or food is akin to detective work. Samples must be processed without introducing contaminations, and analytical methods reach their limits when dealing with the smallest particles. Furthermore, some types of microplastics produce similar or even identical signals to naturally occurring substances, such as the body’s own fats. Moreover, different methods make it difficult to compare studies – and consequently, the results vary considerably in some cases.

NO ACUTE TOXIC EFFECT

Microplastics are considered chemically unreactive and have no acute toxic effect. However, there is currently little awareness about how they influence cellular mechanisms. It is conceivable that they could interact with enzymes or immune cells, thereby interfering with metabolic processes or the immune system. It is also unclear whether microplastic deposits in the body can lead to long-term effects and whether any effects are even possible under realistic exposure conditions.

Another question scientists are investigating is: Does a potential health risk lie in the particles themselves or in the chemical substances that the particles contain or may carry on their surface? There is currently no reliable evidence of specific health effects. Further research is needed.

The BfR-Podcast

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Copyright BfRshort forGerman Federal Institute for Risk Assessment

  • Episode: Microplastics

    Microplastics can now be found almost everywhere: in the air we breathe, in food and inside our own bodies. But where do these microplastic particles actually come from? In the BfRshort forGerman Federal Institute for Risk Assessment science podcast ‘Risiko – On Poisons, Hazards and Health’ you can find information about: What happens when we breathe them in or inadvertently ingest them through our food? Do microplastics really pose a health risk to us humans? And do we really consume the equivalent of a ‘credit card’ of microplastics every week?
    External Link:Go for the podcast (in German) “Mikroplastik: Kleine Partikel – großes Risiko?”