Environment

Scientists review 7,000 studies on microplastics, and their startling conclusions are a warning to humanity

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It’s been 20 years since the journal Science published a paper showing the accumulation of tiny plastic fragments and fibres in the environment, particles that the journal dubbed “microplastics”.

This paper opened up an entirely new field of research, and since then, over 7,000 studies have been published demonstrating the pervasiveness of microplastics in the environment, wildlife and people.

So, what have we learned? In a paper published today, an international group of experts, including me, summarise the current state of knowledge.

This means that microplastics are widespread and have accumulated in even the most remote parts of the planet, and there is evidence of toxic effects at all levels of biological tissue, from tiny insects at the bottom of the food chain to apex predators.

Microplastics are widespread in food and drink and can be found throughout the human body, and evidence of their harmful effects is emerging.

The scientific evidence is now more than sufficient that collective global action is urgently needed to address microplastics, and the issue has never been more pressing.

Small particles, big problems

Microplastics are generally recognised as plastic particles with a side length of 5mm or less.

Some microplastics are intentionally added to products, such as microbeads in facial soaps.

Others are produced unintentionally when larger plastic products break down, such as the fibres released when you wash a polyester fleece jacket.

Studies have identified the main sources of microplastics as follows:

Cosmetic cleaning agents, synthetic fibers, car tyres, plastic coated fertiliser, plastic film used as mulch in agriculture, fishing ropes and nets, “rubber chip filler” used in artificial turf, plastic recycling.

Science still doesn’t know how quickly larger plastics break down into microplastics, and is still learning how quickly microplastics turn into “nanoplastics” — even smaller particles that are invisible to the naked eye.

Measuring the threat of microplastics

Assessing the amount of microplastics in the air, soil, and water is difficult, but researchers have been trying.

For example, a 2020 study estimated that between 800,000 and 3 million tonnes of microplastics enter the Earth’s oceans each year.

Moreover, recent reports suggest that the amount of CO2 leaking into land-based environments may be three to ten times greater than the amount leaking into the ocean, which could total 10 to 40 million tonnes.

There’s more bad news: By 2040, the release of microplastics into the environment is likely to more than double. Even if humans stopped microplastics from entering the environment, the degradation of larger plastics would continue.

Microplastics have been found in more than 1,300 animal species, including fish, mammals, birds and insects.

Some animals mistake plastic particles for food and ingest them, which can lead to intestinal blockages and other problems. Plastics can also release chemicals that can harm animals, or that are attached to the plastic itself.

Invaders in the body

Microplastics have been found in the water we drink, the air we breathe and the foods we eat, including seafood, table salt, honey, sugar, beer and tea.

Contamination can occur in the environment or as a result of food processing, packaging, and handling.

More data is needed on microplastics in human foods, including terrestrial animal products, grains, cereals, fruits, vegetables, beverages, spices, and oils and fats.

Concentrations of microplastics in food vary widely, meaning different levels of exposure for people around the world, but estimates that humans ingest a credit card’s worth of plastic every week are grossly exaggerated.

With improvements in equipment, scientists have identified smaller and smaller particles. Scientists have found microplastics in our lungs, liver, kidneys, blood and reproductive organs. They pass through the protective barriers of our brains and hearts.

While some microplastics are excreted through urine, feces and lungs, many remain in the body for long periods of time.

So how does this affect the health of humans and other organisms? Over the years, scientists have changed the way they measure this.

Initially, they used high doses of microplastics in their lab tests, and now they are using more realistic doses that more accurately represent what humans and other organisms are actually exposed to.

Microplastics have different properties – they contain different chemicals, they interact differently with liquids and sunlight, and they also vary from one species to another, including humans.

This makes it difficult for scientists to conclusively link exposure to microplastics and their effects.

With regard to humans, progress is being made: in the coming years we can expect to have clearer information about its effects on our bodies, including:

Inflammation, oxidative stress (an imbalance of free radicals and antioxidants that damage cells), immune response, and genotoxicity (damage to the genetic information in cells, causing mutations and potentially cancer).

What can we do?

Public concern about microplastics is growing, and this is compounded by the fact that it is nearly impossible to remove them from the environment, which means we are likely to be exposed to them over the long term.

Microplastic pollution is the result of human actions and decisions: we created the problem and now we must create the solution.

While some countries have implemented laws to control microplastics, they are not enough to address the challenge, which is why a new legally binding agreement, the UN Global Plastics Treaty, offers a key opportunity: the fifth round of negotiations will begin in November.

The treaty aims to reduce global plastic production, but the agreement must also include measures to specifically reduce microplastics.

Ultimately, plastics need to be redesigned to prevent the release of microplastics, and individuals and communities need to be mobilized to support government policies.

After 20 years of research into microplastics, there is still much to be done, but the evidence is more than enough to take action now.

Courtesy of The Conversation

This article is republished from The Conversation under a Creative Commons license. Read the original article.conversation

Citation: Scientists review 7,000 studies on microplastics; their startling conclusions alarm humanity (September 22, 2024) Retrieved September 22, 2024 from https://phys.org/news/2024-09-scientists-microplastics-alarming-conclusion-humanity.html

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