Microplastics in Canned Food: What You Need to Know

The Hidden Plastic Lining Inside Every Can

Canned food has been a kitchen staple for over two centuries. It is affordable, shelf-stable, and provides convenient access to everything from tomatoes and beans to tuna and soup. But there is something inside those metal cans that most consumers never think about: a thin polymer lining that coats the interior of virtually every food can sold today. This lining, originally designed to prevent metal corrosion and food spoilage, is made of plastic, and it is a direct source of microplastic contamination in your diet.

The most common lining material has historically been epoxy resin containing bisphenol A (BPA), a known endocrine disruptor. In response to consumer pressure, many manufacturers have shifted to BPA-free alternatives, but as with plastic containers, the replacements are not necessarily safer. Meanwhile, research is increasingly finding that these can linings release microplastic particles into the food they are supposed to protect, adding another layer of concern to an already complicated picture.

How Microplastics Enter Canned Food

Can Lining Degradation

The primary source of microplastics in canned food is the polymer lining itself. These linings are typically made from epoxy resins, polyester, vinyl, acrylic, or polyolefin-based coatings. Over time, and particularly under the high-heat conditions of the canning process (which involves heating cans to sterilize their contents), the lining can degrade and release microscopic plastic particles into the food. Acidic foods like tomatoes and citrus accelerate this degradation because acids interact chemically with the polymer coating, causing it to break down more rapidly.

Chemical Leaching from Linings

Beyond physical microplastic particles, can linings leach chemical additives into food. BPA has been the most studied of these, with research linking it to hormone disruption, reproductive problems, cardiovascular disease, and metabolic disorders. Studies have found that eating canned food just once a day for five days can increase urinary BPA levels by more than 1,000% compared to eating fresh food. Even BPA-free linings often contain bisphenol S (BPS) or other chemicals with similar endocrine-disrupting properties.

Pre-Existing Contamination of Contents

Some microplastics in canned food may originate before the food is even canned. Fish and shellfish, for example, accumulate microplastics from ocean pollution during their lifetimes. When these seafood products are canned, they bring their existing microplastic load with them. Similarly, vegetables grown in soil treated with biosolids (recycled sewage) can contain microplastics absorbed from the growing medium. For more on this topic, see our article on microplastics in seafood.

Which Canned Foods Have the Highest Microplastic Contamination?

Not all canned foods carry the same microplastic risk. Several factors determine how much contamination a specific canned product is likely to contain.

Canned Tomatoes and Tomato Products

Tomato-based products consistently rank among the most contaminated canned foods. Tomatoes are highly acidic, with a pH around 4.0, which aggressively interacts with can linings. Canned tomato paste, crushed tomatoes, and tomato sauce all show elevated levels of both microplastic particles and BPA or BPA-substitute leaching. Studies have found that canned tomato products contain significantly higher BPA concentrations than nearly any other canned food category.

Canned Soups

Canned soups present a double concern. Many contain acidic tomato-based broths that interact with can linings, and they also tend to have high fat content from cream or oil bases, which facilitates additional chemical leaching. A Harvard School of Public Health study found that people who ate one serving of canned soup per day for five days had urinary BPA concentrations more than 1,200% higher than those who ate fresh soup.

Canned Tuna and Other Seafood

Canned seafood carries a dual burden. The fish themselves contain microplastics accumulated during their lives in increasingly polluted oceans, and the can lining adds further contamination. Tuna, sardines, and other oily fish are particularly affected because the fat content of the fish facilitates chemical extraction from the lining. Additionally, the oil or brine solution the fish is packed in provides another medium for microplastic transfer.

Canned Coconut Milk and Cream

High-fat canned products like coconut milk and coconut cream are often overlooked but can contain significant contamination. The high fat content makes these products particularly effective at extracting chemical additives from can linings. Some testing has found elevated BPA levels in canned coconut products compared to their fresh or carton-packaged equivalents.

Fresh vs. Canned: How Big Is the Difference?

The difference in microplastic and chemical exposure between canned and fresh food is substantial. Studies comparing urinary BPA levels in people who eat primarily fresh food versus primarily canned food consistently find differences of 10x or more. Fresh tomatoes contain essentially no microplastics from packaging (though they may contain some from agricultural contamination), while canned tomatoes are among the most contaminated food products tested.

However, the comparison is not entirely straightforward. Fresh produce can be contaminated by microplastics from plastic packaging at the store, from soil contamination during growing, and from plastic cutting boards and storage containers in your kitchen. The advantage of fresh food is not that it is microplastic-free, but that it avoids the significant additional contamination layer that can linings add.

Frozen food offers a middle ground. Frozen vegetables and fruits are typically packaged in plastic bags, which do leach some microplastics, but at far lower rates than metal can linings because they are not subjected to the extreme heat of the canning process. Frozen food generally has lower microplastic contamination than canned equivalents, while offering similar convenience and shelf stability.

Safer Alternatives and Smarter Choices

Completely avoiding canned food may not be practical or desirable for everyone. Here are strategies to reduce your microplastic exposure while still enjoying the convenience that canned foods provide.

Choose glass-jarred alternatives. Many products that come in cans are also available in glass jars. Tomato sauce, pasta sauce, beans, and even some soups can be purchased in glass. Glass is inert and does not leach any chemicals or microplastics into food.

Look for BPA-free lined cans. While BPA-free does not eliminate all concerns, some newer lining technologies such as oleoresin and acrylic-based coatings may leach fewer total particles than traditional epoxy linings. Brands like Eden Foods and Amy's Kitchen have been early adopters of BPA-free can lining technology.

Prioritize fresh or frozen for high-risk foods. For tomatoes, soups, and coconut milk, the shift to fresh or frozen alternatives has the biggest impact on reducing exposure. Use fresh tomatoes for sauces when possible, or buy tomatoes in glass jars or cartons.

Rinse canned foods before use. While this does not remove microplastics embedded in the food itself, rinsing canned beans, vegetables, and other products under water can reduce some of the surface contamination from the liquid they were packed in.

Use the MicroPlastics app to compare products. The MicroPlastics app lets you scan product barcodes at the store to compare microplastic risk across different brands and packaging types. This makes it easy to identify which canned products are safer and when a glass-jarred or fresh alternative is available. Checking before you buy takes seconds and can meaningfully reduce your household's cumulative exposure over time.

Rethinking the Pantry Staple

Canned food has served an important role in global nutrition for over 200 years. It is affordable, accessible, and reduces food waste through long shelf life. But the evidence on microplastic and chemical contamination from can linings is now too substantial to ignore. You do not need to eliminate canned food entirely, but being strategic about which canned products you buy, how often you consume them, and when to choose alternatives can make a real difference in your long-term microplastic exposure. As with most aspects of microplastic reduction, small, consistent changes in purchasing habits add up to meaningful results over time.