We're Eating a Credit Card's Worth of Plastic Every Week. Here's What the Science Says.
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The phrase "eating a credit card's worth of plastic every week" first appeared in a 2019 report commissioned by WWF. It's been quoted in hundreds of headlines since — and for good reason. The estimate, roughly 5 grams of microplastic particles per week per person, is striking enough to stop you mid-scroll. But what does the science actually say? Is the figure accurate, where is all this plastic coming from, and what does regular microplastic intake mean for your health?
This article breaks down the research behind the headline, looks at the main sources of microplastics in food and water, and explains what you can realistically do to reduce your exposure starting today.
Where Does the "Credit Card" Figure Come From?
The 5-gram estimate came from a study conducted by the University of Newcastle, Australia, which analysed existing research on microplastic consumption across food, water, and air. The researchers aggregated data from dozens of peer-reviewed papers to model how much plastic the average person ingests each week. Five grams is roughly the weight of a standard credit card — a memorable comparison that stuck.
It's worth noting that this is an estimate, not a precise measurement. Some researchers have since argued the real figure could be higher, since sampling methods for nanoplastics — the tiniest plastic fragments — have improved significantly since 2019. A 2024 analysis in Environmental Science & Technology suggested total plastic ingestion may be substantially underestimated when nanoplastics are factored in.
The Biggest Sources of Microplastics in Your Diet
Drinking water is consistently identified as one of the largest contributors. Bottled water in particular contains significantly more microplastic particles than tap water filtered through a carbon or reverse osmosis system. One study found that a litre of bottled water contained an average of 240 microplastic particles, compared to fewer than 6 per litre from filtered tap water. Sea salt, fish and shellfish, and packaged foods stored in plastic containers are also major sources of microplastic intake.
Plastic cutting boards are another underappreciated culprit. Research published in Environmental Science & Technology found that a single plastic polyethylene cutting board can shed anywhere from 7 to 50 million microplastic particles into food each year, depending on knife pressure and board age. Air is also a factor — studies have detected synthetic fibres falling from indoor air onto food surfaces, adding to total ingestion.
What Microplastics Actually Do Inside the Body
Most ingested microplastics pass through the digestive system and are excreted. But "most" is not "all." Research has confirmed that smaller particles — particularly nanoplastics under 1 micrometre — can cross the gut lining and enter the bloodstream. A landmark 2022 study in Environment International detected microplastics in human blood samples for the first time, and subsequent studies have found them in the lungs, liver, kidneys, and even placental tissue.
The health implications are still being studied, and scientists are careful to distinguish between finding plastic and proving harm. However, concern is growing around two mechanisms: physical irritation from particles accumulating in tissue, and chemical leaching from plastic compounds including BPA, phthalates, and other endocrine disruptors. The longer-term picture of what microplastic intake means for human health is one of the most active areas of research in environmental medicine today.
Simple Swaps That Reduce Your Microplastic Intake
You can't eliminate microplastic exposure entirely — it's now present in the environment at a global level. But a handful of practical changes can meaningfully cut how much you ingest each week. The highest-impact areas are your drinking water, your food prep surfaces, and how you store food.
The Bottom Line
The credit card comparison is eye-catching, and the underlying research is real — humans are ingesting measurable amounts of microplastic every week through food, water, and air. The science on long-term health effects is still developing, but the precautionary case for reducing exposure is strong. The good news is that a few targeted swaps — filtering your water, replacing plastic cutting boards, and ditching plastic food containers — can make a meaningful dent in your weekly intake without overhauling your entire life.
Start with your water. It's the single highest-impact change most people can make.