Madeline Clough, a grad student at the University of Michigan, stumbled upon something that would turn out to be quite embarrassing for the microplastics research field.
The popular claim is that the amount of plastic in a credit card is roughly how much enters the human body every week [1].
But when Madeline was running a routine air sampler on the roof of a chemistry building for her microplastic research, the numbers coming off her sampler were thousands of times higher than expected.
She couldn't explain it. The benches were clean. The water was clean. The samples she was testing were clean. Why was her sampler generating sky-high results?
She called it a wild goose chase [2]. But what she found would send shockwaves through the microplastics research field.
Table of Contents
- Where the credit card number came from
- The gloves were the problem
- The fat-as-plastic problem
- The chemicals worth worrying about
- How to reduce your exposure
- References
Where the credit card number came from
To understand why Madeline's strange results matter, it helps to go back to where that credit-card headline came from in the first place.
Four years before her air sampler started reading impossible microplastic numbers, in 2019, the World Wildlife Fund commissioned a report. The goal was to estimate how much plastic the average person consumes in a week. They hired the consultancy Dalberg Advisors to do the math. The consultants, working with researchers at the University of Newcastle, put a number together [3].
It was a calculation that combined over 50 earlier studies. Different measurement methods. Different definitions of how small a piece had to be to count. Different guesses about how much people swallow. Added together.
The actual range the math gave was 0.1 grams to 5 grams per week. A 50-fold range [4].
The press release picked the top end. Five grams. The weight of a credit card [5]. Because that's what generates clicks.
But when other groups re-ran the math with more careful guesses, the answers came back smaller. Much smaller. One alternative estimate landed at less than the weight of a grain of salt per week — a median of 4.1 micrograms for adults [6]. Not exactly an amount that would generate clicks for newspapers.
And this overestimation of microplastics exposure based on an exuberant calculation is the first of three issues. Madeline Clough's discovery found that even those smaller estimates of microplastic exposure are probably wrong.
The gloves were the problem
Here's what she found. To check whether a sample contains plastic, researchers shine a focused infrared beam at it. Different materials vibrate at different frequencies — plastic has a fingerprint, fat has a fingerprint. The instrument matches the sample against a library of reference fingerprints. It's called vibrational spectroscopy, and it's the main method used in microplastics research [7].
Madeline's question was simple. The microplastic field had spent twenty years worrying about experiment contamination. Researchers wanted to make sure they were accurately measuring microplastic quantities in their samples. So they carefully ran control experiments. They thoroughly cleaned their equipment and used clean benches. All in an effort to make sure that the lab equipment wasn't shedding microplastics into the samples and throwing off the results.
So when Madeline's air sampler was throwing off sky-high results, she started by thoroughly checking her equipment. Was it plastic from the squirt bottle on the bench? Was it particles floating in the lab air where she was preparing the metal sampling discs? She ruled them out one at a time.
Just as she was about to call it quits, she had a eureka moment. Everyone wears nitrile or latex gloves while handling samples. Standard lab practice. Nobody had checked whether the gloves themselves were shedding microplastics into the samples.
So she tested seven brands. Three latex, three nitrile, one cleanroom-grade nitrile. She pressed each glove against a clean surface with a set amount of pressure, then ran the test on what got left behind [8].
Two thousand false-positive particles per square millimetre on standard gloves. That was the key finding. About a hundred on cleanroom gloves. That's what Madeline's air sampler was detecting. Particles from her gloves.
The contaminant from the gloves turned out to be stearate — a slippery coating manufacturers use so the gloves don't stick to the molds during production. Stearate has a fingerprint similar enough to polyethylene — the most common plastic — that the vibrational spectroscopy was confidently calling it polyethylene by mistake.
Then Madeline wondered if the entire microplastics research field had made the same mistake. Were they just detecting contaminants from the gloves? She read through the method sections of recent microplastics quality-control reviews — the papers that tell researchers how to run a clean experiment — and found that 81% of them recommended wearing gloves. Only two flagged the risk of sample contact. Two. The field had a blind spot, and it was sitting on every pair of hands in every lab.
It turns out this should have been caught earlier. Six years before Madeline's paper, in 2020, a group at the German Federal Institute of Hydrology published essentially the same warning [9].
The fat-as-plastic problem
So there are serious issues with the original math estimating microplastic exposure, and many experiments were contaminated by the gloves researchers were wearing.
That brings us to the third major issue with the microplastics research field.
The most-shared microplastics finding of the last two years didn't use the fingerprint method that Madeline Clough reported on. It used a different one — Py-GC-MS analysis.
The researcher who took a hard look at it works in Brisbane. Cassandra Rauert runs a lab at the Queensland Alliance for Environmental Health Sciences — among the first groups in Australia to explore how plastics circulate inside the human body. In her own words: "Plastics are now being reported in places we never imagined — from the bloodstream to the brain. But the science is still catching up." The gap between what the headlines said and what the methods could actually justify — that's what she set out to measure [10].
Py-GC-MS identifies plastics by heating a sample and analyzing the chemical fragments released. It can estimate how much plastic is present in the tissue. That's why it's the method behind the headlines about how much plastic is in some organ or other [11].
Take a look at this scary-sounding finding, for example. In February 2025, Nature Medicine published a paper claiming human brain tissue samples in the study contained a median of 4,917 micrograms of microplastics per gram of brain — half a percent of the human brain, by weight, made of plastic [12].
But Cassandra was skeptical. And in January 2025, she and her group published a paper that quietly dismantled these scary headlines. The problem is that fat, when heated, breaks down into pieces that look exactly like polyethylene to the instrument. The two can't be distinguished.
Cassandra's group found that the problem of mistaking fat for plastic had not been adequately addressed in those prior studies, including the famous Nature Medicine brain tissue study [13].
Cassandra's findings were backed up by other researchers, who independently raised concerns that the observed polyethylene signals may have come from residual fatty acids rather than synthetic polyethylene. This is reinforced by the lipid-rich nature of brain tissue (~60% lipid by dry weight), compared to the liver and kidneys (under 5%) [14].
So three separate methodology issues — suspect math, gloves contaminating samples, and fat being mistaken for plastic. With all of this uncertainty in the microplastics research field, is there anything to be worried about? Are microplastics actually accumulating in our bodies, causing issues, or not?
It's really difficult to say.
The chemicals worth worrying about
What the evidence is far more settled on is the data for bisphenol A (BPA), phthalates, and PFAS — the so-called "forever chemicals".
BPA is the chemical used to make hard, clear plastics and the lining inside food cans. Phthalates are softeners added to vinyl plastic. Both leach out when plastic is heated or scratched. Both are measured directly in human urine — the test looks for the actual BPA molecule, not a fingerprint match. So there are no matching errors or fat confusion to worry about here.
There are no randomized trials, but observational studies link these exposures to cardiovascular mortality, metabolic disruption, and reproductive problems. It's the strongest evidence we have linking plastic-related chemicals to actual disease in humans. In a nationally representative sample, phthalate exposures were associated with all-cause and cardiovascular mortality, with societal costs approximating $39 billion a year or more [15].
A recent review of BPA evidence linked exposure to obesity and reproductive dysfunction [16].
PFAS are a large class of compounds used in a range of products, including nonstick cookware and waterproof fabrics. Though research is ongoing, evidence links PFAS exposure to decreased fertility, increased risk of some cancers (prostate, kidney, testicular), and hormone disruption [17].
How to reduce your exposure
So how can you reduce exposure to these chemicals? Here are some strategies with the biggest potential payoff.
For BPA and phthalates, avoid heating food in plastic containers. Heat is when leaching is highest. When food is wrapped in plastic or placed in a plastic container and microwaved, BPA and phthalates may leak into the food [18]. Glass and ceramic are safer alternatives in the microwave.
For PFAS, an important source that contaminates food is nonstick cookware. Microwave popcorn bags can also be a concern — these are the food-contact materials on which the most migration tests have been done, and where the highest PFAS content has been found, probably because they reach very high temperatures and are used for long periods [19].
Cook with stainless steel or cast iron pans instead. And make your popcorn the old-fashioned way.
And look for products — especially when they're used in food preparation — that are BPA-free and PFAS-free. When the broader science is still developing, these are practical steps that cut exposure to the chemicals with the most established evidence behind them.
References
1. https://www.cnn.com/2022/10/31/us/microplastic-credit-card-per-week
3. https://wwfint.awsassets.panda.org/downloads/plastic_ingestion_web_spreads.pdf
4. https://www.sciencedirect.com/science/article/abs/pii/S0304389420319944
6. https://www.sciencedirect.com/science/article/pii/S2666911022000247
8. https://pubs.rsc.org/en/content/articlelanding/2026/ay/d5ay01801c
9. https://pubs.acs.org/doi/10.1021/acs.est.0c03742
11. https://pmc.ncbi.nlm.nih.gov/articles/PMC10050779/
12. https://www.nature.com/articles/s41591-024-03453-1
13. https://pubs.acs.org/doi/10.1021/acs.est.4c12599
14. https://www.nature.com/articles/s41591-025-04045-3
15. https://pmc.ncbi.nlm.nih.gov/articles/PMC8616787/
16. https://pubmed.ncbi.nlm.nih.gov/41804233/
17. https://www.epa.gov/pfas/our-current-understanding-human-health-and-environmental-risks-pfas
