Do Cans Have BPA? How It Gets Into Food

Most metal food and beverage cans sold today still contain BPA, though the amount varies by product and manufacturer. The inside of a typical can is coated with a thin polymer lining, and for decades the dominant lining material has been an epoxy resin made from bisphenol A. That resin does not stay perfectly inert: small amounts of BPA break free and dissolve into the food or drink inside, especially when heat is involved. How much ends up in your meal depends on what the food is, how it was processed, and how long it sat on the shelf.

Why Cans Have a Coating in the First Place

Without a protective barrier, the metal wall of a can would react with its contents. Acidic foods like tomatoes would corrode steel or aluminum, producing off-flavors, discoloration, and potentially unsafe metal levels. The internal polymer coating serves two jobs: it keeps the food from degrading the metal, and it keeps metal ions from leaching into the food. Epoxy resins built from BPA have been the industry standard for this purpose because they adhere well, resist acids and fats, and survive the intense heat of commercial sterilization.

BPA-based epoxy is not the only option. Vinyl, polyester, phenolic, and oleoresin coatings are also used, sometimes in combination with epoxy layers. But epoxy remains widespread, particularly for products that are acidic, fatty, or heat-processed aggressively.

How BPA Leaves the Lining and Enters Food

BPA molecules are not locked permanently into the epoxy matrix. Some remain as unreacted monomers left over from the manufacturing process, and others break free as the polymer slowly degrades. Several factors speed that release.

Temperature is the biggest driver. During commercial canning, food is sealed inside the can and then sterilized at high heat, often above 100 °C. One study of cans from the Lebanese market found that sterilization caused BPA levels in the food to jump from an average of about 0.15 to 109 micrograms per kilogram, a roughly 700-fold increase in a single processing step.¹ That heat burst during manufacturing accounts for most of the BPA that ends up in the finished product.

After sterilization, migration continues at a slower pace. Higher storage temperatures, longer shelf life, acidic or alkaline pH, exposure to sunlight, and the presence of certain minerals all push more BPA out of the coating over time.² Research on epoxy resins in water systems has shown that BPA leaching follows a two-phase pattern: an initial peak right after the coating contacts the liquid, followed by a second rise as the resin itself starts to deteriorate.³ In practical terms, a can sitting in a hot warehouse for months will have more BPA in the food than the same product stored cool and consumed quickly.

Which Canned Foods Have the Most BPA

Not all canned foods are equal. The type of food, the type of can, and the specific coating all matter. A Canadian total diet study found the highest BPA levels in canned fish (about 106 nanograms per gram), followed by canned corn (roughly 84 ng/g), canned soups (22 to 44 ng/g), and canned baked beans (about 24 ng/g).⁴ That same study found that canned and jarred foods accounted for the overwhelming majority of dietary BPA intake; the contribution from non-canned foods was small.

An Iranian study of canned fruits and vegetables tells a similar story but adds an interesting detail: canned vegetables tended to have higher BPA than canned fruits, with a mean around 8 micrograms per kilogram for vegetables compared to lower levels in fruits. The researchers suggested this may be because fruit cans more often use electrolytic tinplate rather than epoxy films.⁵ Among vegetables, canned lentils stood out with a mean concentration of nearly 22 micrograms per kilogram.

A tracking study looking at trends from 2008 to 2020 found that BPA levels in several categories have not declined over time, with some of the highest readings appearing in recent samples: up to 57 ng/g in canned evaporated milk, 56 ng/g in luncheon meats, and 103 ng/g in baked beans.⁶ The lack of a downward trend suggests that many manufacturers are still using BPA-based epoxy coatings for these products, despite years of consumer pressure and media attention.

What Eating Canned Food Does to Your BPA Levels

Population-level biomonitoring confirms that eating canned food measurably raises the amount of BPA your body processes. An analysis of over 7,000 participants in the U.S. National Health and Nutrition Examination Survey found that people who ate one canned food in the previous 24 hours had about 24% higher urinary BPA concentrations than those who ate none, and people who ate two or more canned foods had about 54% higher concentrations.⁷ The dose-response pattern was consistent: more canned food meant more BPA in urine.

Canned beverages produce an even more dramatic spike. A randomized crossover trial had participants drink the same soy milk from either a can or a glass bottle. Urinary BPA after drinking the canned version shot up more than 1,600% compared to the glass-bottled version.⁸ That trial also noted a temporary rise in blood pressure after the canned drink, though the clinical significance of such a short-lived change remains debated.

Your body does process BPA fairly quickly. After you swallow it, your liver converts nearly all of it into an inactive form called a glucuronide conjugate. Free, active BPA makes up less than 1% of total BPA in the blood at any point after oral exposure, and the conjugated form is mostly cleared through urine within 24 hours.⁹ Earlier research found a blood half-life of less than six hours for the conjugated form.¹⁰ The rapid clearance is one reason some toxicologists argue that dietary BPA exposure at current levels poses little risk. But the counter-argument is that most people eat canned foods regularly, so exposure is continuous rather than one-off.

Why BPA Worries Health Researchers

BPA’s structural resemblance to estrogen is what makes it controversial. The molecule fits into estrogen receptors and can lock them into an active state, triggering downstream gene signaling that the body did not intend.¹¹ This ability to mimic estrogen has linked BPA to changes in cell growth and survival in laboratory studies, and has raised concerns about hormone-associated cancers.¹²

One aspect of BPA’s behavior that complicates the standard toxicology approach is its tendency to produce non-monotonic dose responses. In plain language, that means higher doses do not always produce bigger effects. Sometimes a low dose causes a measurable biological change that disappears at a medium dose and reappears at a high dose. Researchers have documented this pattern across a range of experiments. In a review of the BPA literature, non-monotonic curves showed up in more than 20% of all experiments examined and in at least one measurement in over 30% of studies.¹³

This matters because the traditional way regulators set safe exposure levels is to find the highest dose that causes no observable harm in animal studies, then divide by a safety factor. If BPA has effects at very low doses that vanish at moderate ones, the standard method could miss them entirely. Lab work on pancreatic cells found that BPA at extremely low concentrations (100 picomolar and 1 nanomolar) disrupted calcium signaling, while ten to a hundred times more BPA had no effect.¹⁴ Similar non-monotonic patterns appeared in rat heart cells, where BPA affected the rhythm and calcium handling of the cells in a way that could not be predicted by simply scaling up from higher doses.¹⁵

The Regulatory Tug-of-War

Government agencies around the world do not agree on how dangerous BPA is at the levels people actually encounter from food. In 2023, the European Food Safety Authority dramatically lowered its tolerable daily intake for BPA by a factor of 20,000, setting it at 0.2 nanograms per kilogram of body weight per day.¹⁶ Under that threshold, virtually any amount of canned food consumption would put you over the limit.

That decision triggered sharp pushback. A group of toxicologists published a detailed critique arguing that EFSA’s review was based on a narrow subset of studies and leaned heavily on a few lower-quality animal experiments while ignoring higher-quality data pointing in the other direction. They concluded that the previous tolerable intake, set in 2015 at a much higher level, was still protective of human health.¹⁷ Other regulatory bodies, including the U.S. FDA, have not followed EFSA’s lead and continue to maintain that BPA in food-contact materials at current levels is safe.

This disagreement is not just academic. If EFSA’s threshold is correct, then canned food is a meaningful health risk for the general population, and aggressive reformulation of can linings is urgent. If the higher thresholds used elsewhere are correct, then current exposures sit well within safe margins and the urgency is lower. Honest scientists hold both positions, and the debate turns partly on how much weight to give cell and animal studies that show low-dose effects versus the rapid metabolism data showing that your body clears ingested BPA within hours.

Are “BPA-Free” Cans Actually Safer

Many consumers reach for products labeled “BPA-free,” and some manufacturers have reformulated their can linings accordingly. The problem is that the most common substitutes are structurally related chemicals, and early evidence suggests they may pose similar hazards. Bisphenol S and bisphenol F, the two most common replacements, were tested alongside BPA in a study using human and mouse fetal testicular tissue. Both substitutes reduced testosterone secretion in human fetal testes at the same concentration as BPA, and both showed non-monotonic dose-response curves.¹⁸

A broader review of BPA substitutes found that several of them, including BPS, BPF, bisphenol AF, and a handful of others, show evidence of reproductive toxicity that may operate through the same hormonal disruption pathways as BPA itself.¹⁹ The phrase researchers sometimes use is “regrettable substitution”: swapping out a known problem chemical for a less-studied cousin that turns out to behave the same way. A “BPA-free” label tells you the can does not use bisphenol A specifically, but it does not guarantee the replacement is biologically inert.

Practical Ways to Reduce Your Exposure

If you want to lower the amount of BPA (or its relatives) that migrates into your food, a few strategies follow directly from the leaching research.

Choose fresh or frozen: Fresh vegetables, frozen produce, and dried beans have negligible BPA. Swapping even a few canned items per week can meaningfully cut exposure, given the dose-response pattern seen in biomonitoring data.
Pick glass or cartons: Soups, sauces, and beverages sold in glass jars or Tetra Pak cartons bypass the epoxy-lining issue entirely.
Store cans cool: Since heat accelerates migration, avoid keeping canned goods in hot garages, cars, or near stoves. Refrigerating canned foods you do not plan to eat soon can slow the process.
Use cans promptly: BPA levels rise with shelf time. Buying what you plan to eat soon, rather than stockpiling for years, limits how much the lining degrades.
Do not heat food in the can: Reheating food directly in an opened can pushes more BPA out of the coating. Transfer to a glass or ceramic dish first.

These steps are most relevant for people who eat canned food daily or who are trying to minimize exposure during pregnancy or early childhood, when hormonal sensitivity is highest. For someone who opens a can of beans once a week, the exposure is low and brief, and your liver clears the BPA within a day.

BPA in Non-Canned Foods

Cans get most of the attention, but BPA can show up in unexpected places. The Canadian total diet study detected BPA in items like yeast (about 8.5 ng/g), certain cheeses, breads, cereals, and fast food.⁴ The levels in non-canned foods were much lower than in canned ones, but they were not zero. Some of these trace amounts likely come from contact with BPA-containing packaging earlier in the supply chain, from processing equipment with epoxy coatings, or from recycled paperboard that picked up BPA from thermal receipt paper during recycling.

Thermal receipt paper deserves a quick mention because it represents a completely different exposure route. Many cash register receipts are coated with BPA or BPS as a heat-activated dye developer. Handling receipts regularly, especially with wet or greasy hands, can transfer bisphenols through the skin. For cashiers and retail workers who handle receipts all day, this non-dietary pathway may rival or exceed what they get from food. It is a reminder that can linings are the dominant dietary source but not the only source of bisphenol exposure in daily life.

What Happens When the Coating Is Not Epoxy

Some cans use alternative lining technologies that avoid bisphenols altogether. Polyester-based coatings, acrylic coatings, and plant-derived oleoresin linings are all in use, though each has its own trade-offs. Polyester coatings work well for mildly acidic foods but can struggle with highly aggressive products like tomato paste. Oleoresins are derived from natural sources and have a long track record but perform poorly with fatty or sulfur-rich foods. No single alternative matches epoxy’s combination of versatility, durability, and cost, which is part of the reason the transition has been slow.²⁰

Researchers have also flagged that non-BPA coatings are not automatically migration-free. Any polymer coating can shed trace amounts of its own chemical components into the food. The difference is that the migrating chemicals from, say, a polyester lining have not been studied as extensively as BPA. Some scientists worry the field is paying outsized attention to one well-known chemical while under-scrutinizing the novel mixtures that replace it. The broader lesson from the BPA story may be less about one molecule and more about the fact that a thin plastic film sitting in constant contact with warm, acidic food for months is going to release something, and the question is always whether that something matters for human health.