Polyvinyl alcohol (PVOH)

Why brands use it: it dissolves in the wash, so the dose is pre-measured and there's nothing to pour.

Take care if: you have children under 6, or someone with dementia or a developmental disability lives with you. The researchers who studied the US data advise those households to use ordinary detergent instead of pods. The danger is the concentrated detergent inside the film, not the film itself. Since 2015 the EU has required opaque outer packaging, a deterrent (such as a bittering agent) in the film that makes a child spit it out within 6 seconds, and a film that holds its liquid for at least 30 seconds in water.

Comes from: polymerising vinyl acetate, then hydrolysing it. Australia classes vinyl acetate as "Suspected of causing genetic defects; Suspected of causing cancer". That doesn't mean it's in the product, but it's not a great starting point for something you clean with.

Myth check: "75% of pod film escapes sewage treatment as microplastic": that figure came from a 2021 model, survey and literature review, not measurements, and the research was funded in part by Blueland, a detergent company that went on to petition the US EPA over pod film. In 2023 the EPA rejected that petition, saying the study "does not use measured data" and that the PVA film in its Safer Choice-certified products breaks down into shorter, water-soluble pieces, not microplastics.

Contaminants: leftover methanol and methyl acetate from the process (the EU calls them solvent residues); EU food grade allows up to 1% of each. They're unlikely in a well-made product, but it's a factor you can't see on the label.