How worried should you be about microplastics?

Let’s start with a fact: no, regardless of what you’ve heard, eat a credit card’s worth of microplastics every week. At least not in the normal human diet. But this popular claim raised alarm, especially when it was followed by a series of studies that found that microplastics are piling up everywhere—even on the highest mountainsin the deepest ocean trenches and in the majority distant polar regions – as well as in human heart tissue, liver, kidney, breast milk and bloodstream. If they’re everywhere and we can show in some scientific studies that they can lead to some damage, that’s cause for great concern, right? Well, no, not necessarily.

The reason microplastics are practically everywhere is because plastic is truly a miracle. The arrival of the first plastic, Bakelite, in the early 20th century ushered in an age of materials made to order instead of harvested from nature. As plastics became thinner and cheaper, they spread far and wide, revolutionizing the packaging of food, electronics, and medical devices, to name a few. However, their durability has a disadvantage. The tiny particles have been released into the environment for more than a century and persist for a long time, which is why they have been found in the body tissues and bloodstream of animals both up the food chain and down the – including us – and in many things we consumesuch as salt, beer and drinking water.

So yes, microplastics are probably in you. But don’t stress just yet. When thinking about any type of pollutant in the body, there are a few things to consider. First, there is the issue of size, and there is a huge range in microplastics. Then there is what dosage would have any effect. And finally, whether this effect is actually harmful. Since many studies involve animals, we must also ask whether these animal studies can reasonably be applied to the average human.

Credit card claim

When it comes to microplastics, many of the most alarming news headlines over the past few years have been vague about the size of the microplastics involved or have relied on studies using extremely large doses that are unlikely to reflect everyday reality.

The a big claim that went viraland what seemed to remain was that, on average, every person on the planet consumes up to 5 grams of microplastics per week – or the equivalent of a credit card. That’s according to a 2019 study that used really shoddy math, and it’s simply not true unless you’re taking a very unusual approach to curbing your spending.

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One study found that most of the world’s population gets only 0.0041 milligrams per week, which is less than a grain of salt.
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The study in question was funded by the World Wide Fund for Nature in collaboration with the University of Newcastle. It was a review combining the findings of 59 previous studies on microplastics found in food and water. The problem is that some studies only measured the number of microplastic particles in a sample and others measured the mass of microplastics. This meant that researchers had to rely on estimation to compare the two types of studies. For example, they estimated the mass of microplastic particles found in drinking water using measurements from seawater and the number of particles per liter from drinking water. But microplastics in the ocean and our drinking water are not necessarily the same – if the average size of microplastic particles in the ocean is much larger than those in filtered drinking water, the final calculation will be inflated. Subsequent studies examining the same data found that it did.

So no, we don’t consume 5 grams of microplastics every week – it’s probably much, much less. actually one study they found that most of the world’s population consumes only 0.0041 milligrams per week, which is less than a grain of salt. At this rate, it would take you more than 1.2 million weeks, or more than 23,000 years, to dig through a credit card’s worth of plastic. If you’re immortal, go ahead and worry.

The same researchers did it simulation predict that on average each person accumulates 12.2 milligrams of microplastics in their lifetime, but that the body actually absorbs only 41 nanograms.

In the past few weeks, there have also been new concerns about the quality of studies looking at the amount of microplastics in the body. For example, some studies vaporize tissue samples and then analyze the vapors for the presence of microplastics. However, when fat evaporates, it can produce similar molecules, creating a false positive.

What do microplastics do in the body?

But all this only applies to the amount of microplastics we consume. What they do with us is another question that we don’t really have solid answers to yet. Some evidence suggests behavioral changes and inflammation in mice exposed to microplastics. But the highest dose given to these mice was 1 gram per day, which is astronomical for a human body, let alone a mouse. A study in pigs used 1 gram per week and found that exposure to microplastics affected the expression of 86 genes and induced oxidative stress in the pancreas, which is caused by the body not having enough antioxidants to get rid of unstable molecules that lead to cell damage. But again, the dosage is unrealistic. In fact, in 2022, the World Health Organization warned in the message that most animal studies use much higher concentrations of microplastics than humans are typically exposed to, or use larger microplastic particles than are likely to be ingested by the human body. The report also notes that microplastics circulate through our organs differently than in rodents, making it difficult to extrapolate the results to humans.

Preliminary human studies exist, and one recent study found that microplastics can accumulate in plaques along with fats, cholesterol and blood cells. In people who had these plastic-infused plaques, the researchers saw higher rates of heart attack and stroke—but we can only say that this is related, and not that the microplastics alone caused these results.

Understanding what microplastics do to our bodies is complex. Yes, they contain chemicals that could disrupt our body processes, but in risk assessment we cannot assume that 100 percent of these chemicals will be eliminated immediately into our bodies. Research has shown that assuming the average amount of leaching in our gut results in negligible increases in chemicals. concentration in the surrounding tissue. And these chemicals don’t necessarily accumulate over your lifetime, as they can also leach out of your tissues and escape through your stool.

There have been concerns that other toxins attached to microplastics could enter the body. Or they could interfere with immune responses or cause cell damage or inflammation. But do these effects cause more than, say, other types of air pollution, sun exposure, excess sugar consumption, or the common cold? We just don’t know.

It is understandable that microplastics can be dangerous to our health, and we should find out if this is really the case. It’s a claim that contributes to our feelings of doomerism about the pollution that happens all around us. And just because we don’t use a credit card’s worth of plastic every week doesn’t mean there aren’t any underlying concerns. But the field is still young and we do not yet have accurate data on the effects of microplastics in the body. So I would spend my time worrying about other things until we have more thorough research on the effects of microplastics.

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