Plastic is everywhere in most kitchens: cling film instantly seals food; disposable tableware does not require washing; and dishwasher-safe pods eliminate the need to measure out powders or liquids.
However, all this convenience has a serious drawback. After use, plastic often breaks down into small pieces called microplastics, which end up in the environment and ultimately in our bodies.
In the case of dishwasher containers, companies have tried to develop a dissolving plastic film. Despite this, some researchers are concerned that these capsules may persist in the environment, ultimately increasing other impacts associated with plastic that science is increasingly linked to chronic diseases.
Here's the latest research on how dishwasher pods may affect your health.
Unique plastic used in capsules
Plastics production has doubled over the past two decades and only 9% of them are successfully recycled. The resulting microplastics are so widespread that found in places as distant as ocean trenches and as close as human breast milk.
Although much more research is needed, several studies point to toxic effects exposure to microplastics. For example, study Last year, a link was found between exposure to microplastics, especially through consumption, and harm to reproductive, digestive and respiratory health.
Dishwasher pods are sometimes classified in the same category as microplastics, but they are technically different. The capsules, which are also used for laundry, are wrapped in a plastic called polyvinyl alcohol, or PVA. During the production process of PVA processed to make it more water safe so that the plastic can dissolve easily in water.
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The final product has plastic films that are strong enough to resist tearing when handled with wet hands, but pliable enough for the detergent to “come out and do its job” in the dishwasher, said Lauren Duffy, an environmental toxicologist and senior scientist at the Environmental Working Group.
Rest PVA moleculesonce they dissolve in water, they fall outside the definition of microplastics because they are liquid and not solid. Since the residue is washed away, most experts agree that the risk of toxicity from directly consuming anything left on plates is negligible.
However, that doesn't mean PVA is gone, says Sherry Mason, a chemist and plastic pollution researcher at Gannon University. “To say it dissolves means you don’t see it,” she says. The water still contains PVA molecules when it leaves the dishwasher and heads to the nearest wastewater treatment plant.
What happens—or doesn't happen—at wastewater treatment plants is key to whether people should worry.
What happens to PVA?
Scientists like Duffy say most evidence shows wastewater treatment plants have the right conditions to further break down detergent-grade PVA into forms that cannot accumulate in the environment or the body.
In 2021, Belgian researchers verified this type of PVA is next international recommendations to evaluate the chemicals—and found that after 1–2 months they had degraded enough to be safe. Detergent-grade PVA, with its balance between hardness in the hand and solubility, allows microbes in wastewater treatment plants to eat it and break it down more efficiently than other plastics.
For these reasons, dishwasher pods are approved by the U.S. Environmental Protection Agency (EPA) program that certifies safer products, called Safe choiceAnd EWG Verified program. (Only capsules containing powder are certified; liquid capsules increase the risk of accidental consumption by children.) “We are confident that we have responsibly evaluated PVA intended for detergents,” Duffy says.
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Other researchers are not so sure about these capsules. US water treatment plants are designed to decontaminate “Only solid and liquid waste, no other chemicals in the water,” Mason explains. Charles Rolsky, executive director and senior scientist at the Shaw Institute, a nonprofit organization focused on the links between the environment and human health, says many studies, including his own, show that PVA can pass through wastewater treatment without completely degrading.
It all depends on the temperature, types of microbial communities and other environmental factors on the plants. Tests that follow international guidelines are carried out in a “very controlled environment, but this may contrast with [with] some real-world conditions,” says Varun Kelkar, an environmental engineer who researched plastics at Arizona State University as a graduate student.
Kelkar believes the molecules often end up in rivers and oceans, where their interactions with marine life and other pollutants are unknown, he says. In a 2021 study, Rolski and Kelkar rated The presence of PVA in the environment has revealed its widespread distribution, especially given its “mass production”.
Rolski agrees with many others that these PVA residues are too diluted to be identified as microplastics, but for him that's exactly the problem. “There’s a period of time where PVA doesn’t biodegrade enough and that has an impact,” he says. “It's plastic turning into something we can't even identify.”
“There is certainly evidence in the literature that the film does not degrade completely,” says Christopher Cassotis, an assistant professor and environmental toxicologist at Wayne State University in Michigan.
But others research has found that “wastewater treatment plants naturally harbor a diverse community of microbes that can biodegrade PVA,” says Dan Selecnik, director of environmental health and safety for the American Cleaning Institute, an industry group.
“The science isn't fully determined yet,” says Duffy of the Environmental Working Group, adding that bacteria break down PVA even in laboratory conditions, which are considered less hospitable than those found in wastewater treatment plants. She also notes that Rolski's research may group PVA intended for detergents with other types of PVA, such as those used in fishing gear and textiles. Because they are less water soluble, they break down more slowly. “It’s easy to jump to conclusions and make worse predictions about PVA marketed for detergents if we assume it performs the same as other PVAs,” she says.
Does PVA accumulate in the body?
If PVA molecules do slip past the treatment plant, what then?
Some studies show no obvious harm because the dissolved molecules do not accumulate inside the body. “Water-soluble compounds are less likely to accumulate in fat tissue,” says Duffy.
In 2022, Italian researchers tested the breast milk of 34 women for contaminants and observable plastic in 26 samples. By testing different qualities of plastics, they found that only 2% was PVA. None of it resembled the PVA in detergent capsules, and “there were no filmy bits that you'd expect,” Duffy says. (Most plastic comes from everyday products, such as grocery bags and food containers.)
The fish didn't seem to be harmed either. When Japanese scientists studied their bodies to a type of PVA similar to detergent capsules, the amounts were well below the EPA threshold for evidence that it accumulates in tissues. In 2023, the Environmental Protection Agency cited this study among other studies in dismissal of petition several non-profit organizations, including the Shaw Rolski Institute, to regulate PVA in detergents.
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Rolski notes other studies suggesting that low exposure to water-soluble PVA may impair growth frogs and fish.
Even if PVA found in detergents does not cause direct harm, it is still possible that it carries other toxic contaminants, potentially allowing them to enter our bodies. However, PVA's chemical structure makes it less likely to stick to contaminants such as pesticides, Duffy says. The Environmental Protection Agency has reached same conclusion, and water-soluble PVA does not bind to heavy metalsaccording to a 2021 study.
Rolski and Kelkar argue that the capsules pose health and environmental risks. “The material itself is not toxic,” says Rolski. “But it enters the environment in large quantities. Even if small quantities have moderate negative effects as a vector, we need to study the cumulative effects,” he says.
How to Limit Your Daily Consumption
The cumulative impact of plastic is growing. Plastic is made from petrochemicals, and petrochemical companies increase their plastic production offsets the decline in oil and gas sales. It is planned that plastic production double or even triple by 2050, despite the health and environmental risks studied.
“The best thing is to use less plastic,” says Mason, adding that if people stop buying it, companies will produce less of it. For her, this principle means refusing to wash dishes in the dishwasher. She uses liquid detergent packaged in recyclable aluminum.
But in a world filled with plastic, it's difficult to eliminate all impacts. To keep your sanity in the kitchen, you can focus on limiting the use of plastic that comes into contact with your food. general route into the body.
“I choose my battles,” Cossatis says. Instead of worrying about every toxic plastic in his environment, he focuses on reducing his consumption of microplastics. He uses wood and metal utensils instead of plastic and avoids plastic food containers.
Also consider the other materials inside your dishwasher. If there are plastic tubs or shelving inside, microplastics may be getting into the water supply. (Higher-end dishwashers may have stainless steel tubs, while most shelves have plastic lining.) The same problem occurs if you wash plastic containers. “This is potentially a greater risk than capsules,” Cassotis says. “I don't use the dishwasher often.”
