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Microplastics. It is hard to miss them in the news, in scary headlines, sometimes at my dinner table (“Mom, did you know we eat a credit card’s worth of plastic every week?”).
At the same time, there is a tremendous amount of confusion. What are microplastics, really? Are they the same as nanoplastics? Should we stop using baby bottles? Is it just microwaving plastic that’s a problem, or plastic in general? The questions are endless. I think my father summed it up best in a recent conversation: “So . . . microplastics. Something to worry about, I guess?”
We need context and data to answer his question and all the rest. What are microplastics, why are they a concern, and how much (if at all) should you panic?
What are microplastics?
Microplastics are small plastic particles created by the weathering of plastic items and, in some cases, are directly added to products like cleaners and cosmetics. “Micro” refers to any particle less than 5 millimeters in diameter; you may also hear the term “nanoplastics,” which are particles less than 1 micrometer. Both of these are created as plastic degrades, which happens over time.
The primary health concern with microplastics is that they may be absorbed into our tissues and affect our cells. The small size of the plastics is what makes this a concern. If you (for example) swallowed a plastic ball that was 1 centimeter in diameter, you would just poop it out. This isn’t recommended, but it would not be a significant health concern. But tiny particles can seep into our bloodstream and cells, possibly creating issues. The smaller the particle, the more we are concerned about it getting into our tissues.
One clarification: although you often hear them discussed together, microplastics and phthalates are not the same thing. Phthalates are chemicals (which are often added in the creation of plastics, usually to make them more flexible). Microplastics are tiny pieces of plastic that may also leach phthalates. However, most concerns about phthalates are not about microplastics, since that would be only a small share of our phthalate exposure.
Are microplastics new?
If we’re considering the long timescale of human history, yes, because synthetic plastic wasn’t created until the late 1800s. Before plastics, there were no microplastics. But in the scale of the past several decades, they are not new — as long as plastics have been around, we have had microplastics. In the more recent timescale, it is unclear whether the amount of plastic waste in the ocean (for example) has gone up or down.
Two things have changed over time. One is our ability to detect the presence of these plastics in humans. This has led to more research interest and concern. We had microplastics around in the 1970s, but we didn’t know as much about them. The second change is that there is more old plastic around — plastic from the 1930s, ’40s, ’50s — that is living in landfills and the ocean. As this plastic ages, microplastic particles are released. As they age, they degrade into nanoplastics. We are living with the accumulation of plastics over time.
Our ability to measure the extent of microplastic exposure is more limited than would be ideal, but we have some recent evidence from cadaver organs suggesting that, even over the timescale of the past decade, our exposure to microplastics has gone up.
How do we get exposed to microplastics?
Microplastics come in a wide range of shapes and sizes, and our two primary sources of exposure are ingestion and inhalation. Microplastics are found in dust and ambient air as well as in food and water. We are exposed, therefore, in many different ways; the smallest microplastics may also be absorbed through skin.
There are two ways in which you get microplastics from foods. One is that the food may contain microplastics — some foods may have more microplastics than others, although our perception of differences may be partly due to how much we study them. Fish, for example, are known to have significant plastic burdens. Less research has been done about exposures for land animals.
A second way is that microplastics can leach from our food storage containers, plastic bags, etc. This seems to be more common at higher temperatures.
Plastic water bottles (including plastic baby bottles) may expose you to microplastics, although again, we do not know many details about the importance of this exposure. The perhaps unfortunate reality is that there are a lot of sources of microplastic exposure, and it may be hard to identify changes in your behavior or environment that would significantly change your level of exposure.
How much microplastic are you exposed to?
Are my kids right? Do we consume a credit card’s worth of plastic a week?
No. This notion, at least, is not true. It was based on an analysis that made many assumptions, at least some of which were questionable. An updated version of the analysis suggested that, in fact, the ingestion of microplastics is many orders of magnitude lower than that — that actual ingestion of microplastic may be more like a credit card every few thousand years.
As I mentioned above, though, ingestion is not the only source of microplastic exposure (inhalation is also a pathway), and new research has started to measure the degree of microplastics in various organs. The best of this data comes from cadavers. Measurement there suggests an average of about 6 grams of plastic in your brain, or about one plastic spoon’s worth.
Microplastics have been widely detected in human tissues, including the brain, liver, and placenta. As our measurements improve, we should expect continued evidence of microplastics in human tissues.
Do microplastics affect your health?
Now we get to the biggest question: Does this actually matter for your health? First, let’s acknowledge that a spoon’s worth of plastic in your brain is disturbing. It’s not good! Clearly, there is value to thinking about lowering microplastic exposure in the environment, the same way we have thought about reducing things like air pollution. However, understanding the links with human health can help us frame the size of this concern.
Simply put, we know from studies of cells, mice, and human organoids (clusters of cells that mimic human organs) that microplastics can cause damage at high doses. But there is little evidence on the magnitude of these effects at the doses we see in humans.
This paper provides a helpful review of what we know from animal and cell studies. Microplastics, especially the very small nanoplastics, can enter cells and cause damage. Nanoplastics are especially an issue and (for example) can get into mice brains. Because micro- and nanoplastics damage cells, they are, by extension, possibly harmful to a wide range of organs and systems, since all of our organs are made up of cells.
Evidence from in vitro cell studies, human organoids, and mice suggests possible damage to immune function, reproductive success, brain development, respiratory and renal systems, and more.
The exposures in these studies are much higher than in humans, though. This is a case in which the dose may make the poison. Cells in your body are constantly regenerating. Your body can deal with some level of increased cellular damage, so it is possible that low-level exposure has minimal health impacts.
Direct evidence of the health impacts of microplastics is extremely limited. We do not have even large-scale observational studies that would, say, compare health outcomes for those with more or less microplastic exposure. Such studies will be challenging given the issues with plastic exposure measurements and problems of correlation and causation.
Our evidence on humans is limited to evidence from papers like this one, which show that livers from people with cirrhosis have more plastic than healthy livers. This could be interpreted as saying microplastics contribute to liver failure or, more likely, it reflects differences in lifestyle. (For example, if people who drink heavily are also more exposed to plastic in their food or environment, that would drive this correlation even if it is the alcohol that produces the liver failure.)
The conclusion of this paper provides a nice summary of what we know and do not know about these issues. The authors argue that while there is clear potential for health impacts, the evidence we have from non-human models is difficult to extrapolate to people. And they argue that we need more research.
Is there anything you can do about microplastics?
The most meaningful thing that could happen in this area is more advocacy for cleaning up plastic pollution globally — that’s a worthwhile focus if you’re looking for something to expend energy on. Advocating for more research would also be good.
From an individual standpoint, there is probably nothing you should do. Your options for lowering your microplastic exposure are very limited. Throwing away all the plastic in your house could have a small impact, but this is probably not your main source of exposure. Your main sources of exposure are probably the water you drink and the air you breathe; there’s not much you can do about that. Further, from a health standpoint, this isn’t a five-alarm fire like, say, high-level lead exposure. If you want to switch to glass baby bottles, of course, feel free to do so — but please do be careful. They break.
Concerns about microplastics are constantly in the news, particularly about various class-action lawsuits against companies that have used undisclosed microplastics in their products (baby bottles, Ziploc bags, bottled water, the list goes on). But just because a particular lawsuit is new and making headlines, it doesn’t necessarily mean the information it is based on is new. As hard as it is, try not to panic with every new headline you see—there have been many, and there will be many more.
As to my father’s question on whether one should worry, I will say only that worrying is never a very effective approach. Read the above, decide if you want to make any changes, make them if you do, and try to move on.
The bottom line
- Micro- and nanoplastics are small plastic particles that are created as plastic degrades.
- Microplastics are essentially unavoidable at this point — they are found in dust, air, food, and water — and they have been widely detected in human tissues.
- Research shows that there is clear potential for health impacts, but our main evidence is in non-human models (primarily mice). We need more research to definitively conclude that there are health impacts on humans.
- You have limited options in lowering your microplastic exposure. You can throw away plastic in your house or switch to glass baby bottles, for example, but remember that your primary exposure sources are water and air. Any personal choices will only have a small impact.
Log in
I think this take is correct that it’s hard to take action on an individual level to limit microplastics consumption. But we surely should be agitating for more regulation (yeah, I know the next little while will be a tough time for that).
Here is a recent article adding to the data on possible carcinogenicity:
https://pubmed.ncbi.nlm.nih.gov/39856719/
My medical friends are starting to see people in their 20s come in with liver cancer in startlingly high numbers. They are wondering whether there is a link to the microplastics issue.
My kids’ daycare doesn’t allow glass bottles, but I was so happy to find the kind of bottles that are plastic on the outside with a thin layer of glass on the inside! It seems like heating up milk in plastic can’t be great from a microplastics perspective
The plastic spoon in your brain is a classic Panic Headline that I am sorry Emily is not calling out here. A good assessment from Science Vs podcast is here: https://open.spotify.com/episode/2ZwZsCnG2BkTzPxo5tujOB
Came here to say this! Science Vs did a great job explaining the limitations.
Just this week this came up twice, once when I said I used plastic containers for my preschoolers lunch, which he already thinks is heavy and glass would definitely be heavier and possibly break.
The second time I grabbed a plastic water bottle from my car because it was warmer than expected at the park and I was feeling dizzy. 100% dehydration was going to kill me before the plastic water bottle.
Please drink when you are thirsty and eat when you are hungry even if you have to use plastic sometimes. <3
It is not just the plastic particle itself that is a concern but the chemicals adsorbed to it that may be released once ingested/inhaled. A lot of research has been done into heavy metals, pharmaceuticals, PCBs, etc. the list goes on, that are transported in the environment attached to these micro and nano-plastics, but much more research is needed.