Dissolving the Myth

Not all plastic is worth panicking about — and the science tells you which is which

This piece is in partnership with the American Cleaning Institute. As always, scientific and editorial decisions were entirely our own.

My town recently passed an ordinance banning single-use plastic bags at stores, which I think is a good call. As my plastic cutting boards get scratched, I replace them with wooden ones. I’m slowly swapping plastic food storage for glass and water bottles for stainless steel. Though I’m not turning my kitchen upside down to rid it of any trace of plastics, I do make these changes gradually.

But, despite the terrifying headlines about microplastics in our bodies, brains, and breast milk (oh my!), I’m not panicking. And after spending a lot of time with the evidence on microplastics (including recording a whole podcast episode with Dr. Joe Zagorski, a toxicologist at Michigan State University’s Center for Research on Ingredient Safety (CRIS), which drops soon!) I want to explain why I don’t think you should either.

To ruin the punchline a bit, there’s a big gap between “we should thoughtfully reduce our plastic use over time” and “the laundry pods are poisoning our family.” One is a reasonable position grounded in good environmental thinking and common sense. The other is a marketing pitch by “all natural” brands (an unregulated term by the way) dressed up as science. Let’s discuss…

What even is a microplastic?

Before we get into the weeds, we need to start with a definition of ‘microplastic’ — because that’s a big umbrella, and sometimes certain materials get thrown out with the dishwater.

Microplastics are solid plastic particles smaller than 5 millimeters (about the width of a wedding band). They come in two forms. Primary microplastics are intentionally manufactured at small sizes, such as the microbeads that were common in exfoliating scrubs and have since been banned in the U.S. and many other countries. Secondary microplastics form when larger plastic items break down over time through mechanical stress, UV exposure, and abrasion — think car tires, or synthetic fibers shed from fleece jackets in the wash. Both types persist in the environment. There’s the rub– that persistence is the problem.

But not all polymers (the long-chain molecules that give plastics their structure) behave this way, and this is where things get really interesting. (Prepare yourself, you may have flashbacks to chemistry class!)

Polymers, plastics, and why they’re not the same thing

A polymer is any substance made of many small repeating units (called monomers) linked together in a chain. The word simply describes molecular structure; it says nothing about whether something is natural or synthetic, biodegradable or persistent, dangerous or benign.

Cellulose is a polymer — it’s what wood and cotton are made of. Collagen is a polymer, a major structural protein in your skin. DNA is a polymer. Nylon is a polymer. Polyethylene — the stuff in plastic bags — is a polymer. And polyvinyl alcohol, or PVA, which is what laundry and dishwasher pod films are made of, is also a polymer.

Plastics are a specific subset of polymers: synthetic, durable, and moldable during manufacturing. That word comes from the Latin plasticus, meaning “capable of being molded.” Conventional plastics like those in grocery bags or water bottles are designed to be long-lasting (a selling point for the product but a bug for the environment).

PVA is a different animal entirely.

What actually happens to the pod film

PVA is a water-soluble polymer. But PVA isn’t just one thing. It’s a family of polymers that can be engineered with very different properties depending on the application. Some grades are highly water-soluble and biodegradable, while others are designed to be water-resistant and durable.

A useful analogy: glucose and cellulose are both made of sugar units, but one dissolves rapidly in water and is metabolized quickly, while the other forms the structural material of wood. Same building blocks, very different behavior.

The PVA used in construction materials or textiles behaves very differently from the PVA used in detergent pod films, which is specifically engineered to dissolve rapidly and completely in water. For context, the grade of PVA used in detergent pods is the same grade used to coat pill capsules and to make eye drops.

When your laundry pod hits the wash, or the dishwasher pod hits the dishwasher, the thin PVA outer layer dissolves in the water— not into tiny solid pieces, but into individual polymer chains that become part of the solution. Once that happens, there are no solid particles left. This is why PVA is excluded from the definition of microplastics under both scientific and regulatory frameworks.

In 2023, a European Union microplastics regulation excluded water-soluble polymers, including the highly soluble PVA grades used in detergent capsules, from the definition of microplastics. Water-soluble polymers lose their solid state upon release into the environment. You cannot have a solid plastic particle if there’s no solid.

Once the PVA is dissolved and in wastewater, it behaves like other dissolved organic compounds. In chemistry, ‘organic’ simply means carbon-based (nothing to do with the grocery store label), and wastewater treatment is designed to handle exactly that. Wastewater treatment plants aren’t just filters — they rely on bacteria to break down organic carbon, consuming dissolved material as food. What matters to them isn’t whether the polymer is natural or synthetic; it’s the bond types, the molecule size, and the functional groups attached to it. Modern treatment systems are designed to handle large volumes of organic material daily, from food waste to surfactants, and PVA falls right within that range.

Does dissolved PVA persist in the environment?

We’ve established that PVA dissolves in water rather than breaking down into solid pieces. But people may wonder if the dissolved PVA just persists in the environment indefinitely. That’s where biodegradability comes in.

Biodegradability means that microorganisms (bacteria, fungi) can chemically break a material down into naturally occurring substances: carbon dioxide, water, and mineral salts. Whether something biodegrades has nothing to do with whether a material is natural or synthetic. That depends on the chemical structure and on how easily microbial enzymes can break molecular bonds. Cellulose biodegrades rapidly. Polyethylene doesn’t. Some synthetic polymers biodegrade very well.

There are standardized laboratory tests for measuring biodegradability, developed by the Organization for Economic Co-operation and Development. The most common, OECD 301, uses microbes from activated sludge, sewage water, surface water, and soils to measure aerobic biodegradation under controlled conditions. A substance that passes this test is expected to fully degrade in real-world environments, where additional factors such as heat, light, and pH can accelerate the process. Which means these lab tests may underestimate how well materials biodegrade in the wild rather than exaggerate it.

Detergent-grade PVA passes this testing. Studies as recent as 2024 have confirmed that it biodegrades reliably across multiple countries and under real-world conditions. Wastewater treatment removes approximately 97% of PVA before water is released into the environment, and detergent-grade PVA has not been detected in drinking water, marine environments, or human tissue samples.

Where the scary headlines come from

In April 2023, the EPA reviewed a petition requesting that detergent-grade PVA lose its “Safer Choice” certification — the EPA’s designation for products meeting strict safety standards. The EPA rejected it. Their finding: the petition relied on studies of microplastics generally, not on studies of the water-soluble PVA actually in the pods (aka, they compared apples to oranges). The EPA took it a step further and published a point-by-point rebuttal of a 2021 paper by Rolsky and Kelkar in the International Journal of Environmental Research and Public Health that claimed over 75% of pod-film PVA survives wastewater treatment, finding it contained calculation errors, unsupported assumptions, and crucially, relied on data about conventional microplastics rather than water-soluble PVA.

(Note: the journal that published the original Rolsky paper was removed from Web of Science in 2023, a significant blow to its reach and credibility as a peer-reviewed source.)

Some studies have claimed to find PVA where it shouldn’t be — in drinking water and breast milk — but the details rarely survive scrutiny. One widely cited study reported finding PVA in drinking water in Mexico City, but the chemical match was only 70%; the authors later corrected the paper, concluding that the particle was far more likely to be cellulose, a natural polymer, and not a microplastic. Another claimed to find it in human breast milk, but identified just one particle across 34 samples — and it was brown, whereas detergent-grade PVA film is clear. The study itself acknowledged it couldn’t identify the source.

This pattern — where a high-profile claim generates media coverage that subsequent corrections never quite undo — is not unique to PVA. It’s a recurring feature of how health and environmental science get translated into headlines, and a few structural issues make it worse.

As Jen Novakovich of The Eco Well documents, microplastics are quite tricky to measure; studies use inconsistent techniques and units, labs are full of background contamination that can produce false positives, and certain plastics can be mistaken for other compounds, including bodily fat or residue from lab gloves. On top of that, studies showing something is not harmful are notoriously difficult to publish — the scientific community has a well-documented bias toward positive findings. The alarming headline travels. The correction doesn’t.

What about microplastics more broadly?

The broader concern about plastic pollution is legitimate and worth taking seriously. The evidence that microplastics are accumulating in the environment — and in our bodies — is real. Particles from car tires, synthetic textiles, and conventional plastic packaging are found in oceans, soils, freshwater systems, and human tissue. The long-term health effects of that accumulation are an active and genuinely uncertain area of research. We don’t have definitive answers yet, and saying so is part of being honest about what the science actually shows.

The WHO published a major risk assessment in 2022 and found no conclusive proof that microplastics are causing measurable harm — not a clean bill of health, but an important distinction. EFSA reached similar conclusions in 2025, noting the literature is rife with measurement inconsistencies and replication failures. As Novakovich puts it, if microplastics were having profound impacts at current exposure levels, we’d likely have clearer evidence by now.

A 2025 paper in Environmental Science & Technology Letters, co-authored by CRIS director Dr. Norb Kaminski, is worth the read. It found that microplastics in seafood aren’t the primary source of human exposure, and that the public focus on seafood specifically is wildly disproportionate to the actual risk. The bigger source? Indoor air and dust, by orders of magnitude. It’s a useful reminder that the microplastics concern is legitimate, but where we direct that concern matters.

What the evidence does not currently support is the specific claim that laundry or dishwasher pods are contributing to this problem. PVA is not polyethylene. Soluble is not persistent. And a scary headline is not the same as a peer-reviewed finding that has been replicated.

What this means practically

Some swaps do make sense — not as a panicked overhaul, but as gradual, evidence-based choices. Replacing single-use plastic with reusable bags is a real reduction in a major source of environmental plastic waste. Replacing cutting boards and water bottles as they wear out, rather than in a wholesale purge, is reasonable. Thinking about synthetic textiles is worthwhile. These are places where the evidence is solid and the swap is genuinely straightforward — not just a lateral trade in materials.

Remember that every material has its own downsides… and everything in life is a trade. As Novakovich argues compellingly, swapping one material for another isn’t automatically a win. Total environmental impact includes emissions, energy use, and land use, not just end-of-life pollution. Replacing all plastic with glass, paper, and aluminum would require roughly 3.6 times as much material and 2.2 times as much energy. The materials aren’t the problem. Overconsumption is.

For laundry pods and dish pods? The current evidence doesn’t put them on the list. If you want to switch to powder or tablets for other reasons — cost, packaging preferences, whatever — go for it. But if you’re paying a premium specifically because you’ve been told you’re protecting your family from microplastics, you’ve been sold something the science doesn’t back up.

Good environmental thinking means being precise about what actually causes harm, and spending our limited energy accordingly. Panic is not a conservation strategy.

Stay Curious,

Unbiased Science