Should we be afraid of microplastics?

In recent years, microplastics have received extensive media attention and have become a prominent topic in public debate. According to the latest Eurobarometer survey, concern is increasing: every second Finn now considers microplastics to be the greatest risk to food safety.

But is this concern proportional to the actual risk?

Sensational headlines often obscure the bigger picture

News stories on microplastics are frequently accompanied by sensational headlines. Perhaps the most well known example is the long lived comparison claiming that humans ingest “the equivalent of a credit card’s weight of plastic per week.” This analogy referred to an estimate from an international meta-analysis on the amount of microplastics entering the human body weekly. It has since been shown that this comparison was based on imprecise calculations substantially overestimating the levels of exposure.

Another international biomonitoring study was widely reported with headlines suggesting “plastic chemicals are linked to hundreds of thousands of deaths worldwide.” In reality, the study did not distinguish between sources of chemical exposure, and it is well established that most harmful plastic‑related chemical exposures primarily originate from general exposure pathways, especially food, rather than from microplastic particles.

One of the most recent, widely publicized studies is the so called “plastic spoon study”, which claimed that microplastics equivalent to the weight of a plastic spoon were found in the human brain. Subsequently, the analytical methods used in this study have been questioned, as the signals from the brain lipids can in some analyses produce false positive records and thus, be incorrectly interpreted as microplastics.

Is our level of exposure a cause for concern?

The good news is that the vast majority of microplastics entering the human body are eliminated through natural pathways. Only a very small fraction of particles may translocate into tissues and even into cells. However, we currently lack sufficient knowledge about the potential effects of such small quantities within the body.

Assessing actual exposure levels is extremely challenging. Despite advances in analytical methods, limitations remain. The smallest particles, nanoplastics, cannot yet be reliably quantified. These nanoplastics may behave differently in the body than larger microplastics and may be capable of crossing biological barriers that micro sized particles typically cannot.

Exposure varies depending on where we live, what we eat, how we live, and where we work, making general conclusions difficult.

People living in Finland are, in many respects, in a favorable position. High quality drinking water, clean air, and relatively low consumption of shellfish are factors that significantly reduce our exposure compared with many other countries.

What could cause health effects from microplastics?

Microplastics may exert adverse effects through two main mechanisms: via chemicals associated with plastics as such and through particle related effects.

Plastics contain numerous additives that are used to achieve desired material properties. Some of these additives can be harmful. At sufficiently high concentrations, they may disrupt hormonal activity, metabolism, immune function, and even increase cancer risk.

However, the amounts of chemicals released from microplastics are very small compared with the quantities we are typically exposed to through food.

Current evidence suggests that particle effects may pose a more relevant health concern than chemical exposure itself. Plastic particles can irritate the body, and smaller particles may cross biological barriers and accumulate in tissues and cells. In cell and animal toxicity studies, such particles have been shown to induce local effects such as oxidative stress, cell damage, and inflammatory responses.

According to the WHO, microplastics should be considered alongside other insoluble particles to which humans are exposed to on a daily basis. Microplastics represent only a small fraction of overall particulate exposure. Combustion derived and mineral particles, for example, constitute a substantially greater risk to health.

There is no reason for major concern

Microplastics undeniably pose a risk to the environment, as they accumulate in nature and degrade very slowly. Based on current evidence, however, the associated health risks appear limited. This situation may change in the coming decades if plastic pollution continues to increase in an uncontrolled manner. Therefore, limiting plastic emissions and reducing the use of plastics, particularly in unnecessary applications, is important.

Further research on health effects is clearly needed, but based on the current knowledge, there is no justification for widespread concern regarding human health.