Detergent Pods: Not As Eco-Friendly As Advertised

By Nicholas Gerbis
Published: Monday, August 2, 2021 - 5:15am
Updated: Monday, August 2, 2021 - 10:33am

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Shireen Dooling.

Many companies tout the eco-friendliness of their detergent pods.

But their dissolvable plastic casings rank as a top wastewater pollutant, and a new model-based study in the International Journal of Environmental Research and Public Health suggests most of that polyvinyl alcohol, or PVA, makes it into the environment.

"If you think about putting a spoonful of salt in a glass of water, it might disappear, but you'll still very much taste it. It's still very much a solution," said co-author Charles Rolsky, a postdoctoral researcher at ASU's Biodesign Institute.

Biodegrading PVA takes the right microorganisms, temperature, pH and timespan — conditions not found in most municipal water treatment plants.

Rolsky said he doesn't want to vilify PVA, but companies need to be more transparent.

"I think it's really important that we stress clarity when it comes to these terms. Technically anything is biodegradable. Even the most robust plastics over 10,000 years will be biodegradable," he said. "PVA, under optimal circumstances, is biodegradable. But optimal circumstances don't really exist in conventional wastewater infrastructure."

Nor do they exist in the environment. Rather, accounts of PVA's biodegradability are issued by labs that test it under optimized conditions.

"I'm not denying any of those claims, but it's also important that they use a controlled environment. I don't think that controlled environment actually exists in our environment," said co-author Varun Kelkar, a doctoral candidate at ASU's Biodesign Center for Environmental Health Engineering.

Int. J. Environ. Res. Public Health 2021, 18(11), 6027.
PVA emissions across the U.S.: Untreated PVA via wastewater that does not reach treatment plants (left) and PVA from treatment plant effluent streams (right).

Based on their research, the authors estimate three-quarters of PVA from pods escapes onto the environment. There, based on its chemical properties, it could potentially leach into groundwater, concentrate antibiotics or heavy metals in the food chain, or harm plants and aquatic ecosystems. 

"The pods we are all using in washing our clothes, they are not really being biodegraded, but they are basically coming back in our water streams one way or another," said Kelkar.

"We don't have evidence on this, but that is very likely that's happening."

Besides detergent pods, PVA is used as a sizing and finishing agent in the textile industry and as a thickening or coating agent in paints, glues, meat packaging and pharmaceuticals. But textile plants have wastewater treatment facilities set up to handle PVA. Public water treatment plants, where available, tend to be older and more focused on broader treatment needs.

More research is needed to confirm how the study's model predictions play out in nature, but the authors say the results make sense given what experts know about how PVA chemistry, biodegradation and wastewater treatment.

"We don't say that this is a terrible material. It serves its purpose. We just need to stress that it needs to be studied further. We don't know how it behaves in the environment," said Rolsky.

He added that, if future studies support their findings, a PVA pod might prove somewhat more dangerous than a conventional plastic bottle, which has at least a chance of being recycled.

"And even if it's not recycled, the process by which it turns into a small plastic, a microplastic, is going to be a pretty long period of time. Whereas PVA almost instantly becomes a solution and instantly turns into these probably nano-sized particles," he said.

The study was funded in part by Blueland, a company that markets itself as making eco-friendly cleaning products. It was conducted on behalf of Plastic Oceans International (PCI), a global non-profit that seeks to end plastic pollution and foster sustainable communities. PCI also participated in the research.

Int. J. Environ. Res. Public Health 2021, 18(11), 6027.
Modeled PVA usage and emissions in metric tons per year (mtu/yr) in the U.S.

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