What are the risks to human health?

It’s no secret: when enjoying a delicious piece of fish or a platter of seafood, we consume not only valuable omega-3 acids and vitamin D. In addition to these benefits, there are less appetizing elements – countless micro- and nanoplastics.

These plastic particles, measuring less than 5 millimeters in size, enter our oceans through human waste and enter the food chain. According to Ifremer’s studyThere are approximately 24,400 billion microplastics floating on the ocean surface. These molecules are found in all marine life, from microalgae to fish, which occupy the higher levels of the food chain. This phenomenon not only threatens marine ecosystems, but also raises concerns about potential threats to human health.

What exactly do we know about the accumulation of these pollutants in marine organisms and the risks they pose to human health?

Micro- and nanoplastics: an imperceptible threat

Since the 1950s, plastic production has increased exponentially, reaching 58 million tons in Europe only in 2022. This has led to the creation of huge amounts of waste.

Over time, wind, waves, sunlight and microorganisms break down larger plastic waste into microplastics (1-5 mm) and nanoplastics (smaller than 100 nanometers), which now pollute all parts of the environment, including air, soil and water.

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The process by which these plastics accumulate in organisms at various levels of the food chain is called “bioaccumulation”.

Research from our laboratory reveals that in aquatic environments, micro- and nanoplastics are consumed by a wide range of species – from microalgae at the base of the food chain to top predators such as eels.

Impact on marine life

Such consumption has sedate consequences. Studies show that microplastics can cause toxic effects on marine animals.

In mussels, for example, microplastics can clog the digestive system, activate immune responses, cause DNA damage, and disrupt the expression of genes necessary for various cellular functions.

The severity of these effects depends on the size, composition, degree of degradation and harmful chemical additives that plastics may contain.

Plastics often contain huge amounts of phthalates, which disrupt the functioning of the endocrine system. These chemicals can disrupt the endocrine system, posing a risk not only to marine life, but potentially to humans as well.

Risks to human health

Plastics ingested by marine animals inevitably end up in our food.

Regular seafood consumers are estimated to ingest thousands of microplastic particles each year. Although research into the exact effects on human health is ongoing, some disturbing hypotheses have emerged.

Once in the human body, these particles can cause damage similar to that observed in fish.

Studies on human cells indicate this micro- and nanoplastics can cause interference cellular functions in a manner similar to the effects seen in marine organisms. Scientists are particularly concerned about the toxic effects of plastic additives.

Additionally, micro- and nanoplastics can act as carriers of pathogens or bacteria, potentially increasing the risk of infectious diseases.

The urgent need to address the bioaccumulation of plastics in the food chain cannot be overemphasized. By taking quick action to reduce plastic apply and improve recycling technologies, we can leisurely the progression of the environmental and health crisis.

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This article is part of the Science Festival (October 4–14, 2024), partnered by The Conversation France. This year’s theme “Ocean of Knowledge” highlights critical maritime issues. More about the festival on the website Fetedelascience.fr.