Does packaged milk contain microplastics from the carton or bottle?

What's actually in it

Milk cartons aren't just cardboard. They're lined with polyethylene, a thin plastic film that keeps the milk from soaking through. Plastic milk jugs are made from high-density polyethylene (HDPE). Both types of packaging are in constant contact with the milk from the moment it's filled at the factory until you pour it at home. Over time, tiny plastic particles flake off into the liquid.

What the research says

A 2026 study in Food Chem Toxicol tested packaged milk samples for microplastic contamination. The researchers filtered the milk and analyzed what they found under a microscope.

Every sample contained microplastics. The most common types were polyethylene and polypropylene, the same plastics used in milk packaging. The researchers matched the particles to their likely sources and concluded that most of the contamination came from the packaging itself, not from the processing equipment or the farm.

The study estimated how much microplastic a person swallows from milk alone. For someone who drinks two glasses a day, the annual intake of plastic particles from milk is in the thousands. Kids who drink more milk per body weight get a proportionally higher dose.

The longer milk sits in its container, the more particles it picks up. Milk stored for longer periods before its sell-by date contained more microplastics than freshly packaged samples. Temperature also mattered: milk kept at higher temperatures had more contamination.