Bisphenol A (BPA) is a chemical compound historically used to make epoxy resins, which serve as protective linings inside metal food and beverage cans. While aluminum does not contain BPA, the interior coating was traditionally a BPA-based polymer. This practice has evolved significantly, and whether a can contains BPA now varies greatly by manufacturer and product. Due to public concern, many companies have voluntarily phased out this chemical, meaning a large percentage of cans today are made without it.
Why Can Linings Are Necessary
A protective layer is essential for the safety and quality of canned food and drinks. Without a lining, the metal, whether aluminum or tin-plated steel, would be exposed directly to the contents. This exposure allows the metal to corrode, especially when in contact with acidic foods like tomatoes, fruits, or carbonated soda.
The lining acts as an inert barrier, preventing the metal from dissolving into the food and maintaining the can’s structural integrity. Historically, BPA-based epoxy resins were favored for this purpose due to their durability and effectiveness as a corrosion-resistant seal. The lining also prevents the metal from imparting an unpleasant taste to the product.
Understanding BPA Health Concerns
Concern surrounding BPA stems from its ability to migrate from the can lining into the food or beverage. This migration accelerates when contents are heated during sterilization or are highly acidic. Once in the body, BPA is classified as an endocrine-disrupting chemical (EDC) because it can mimic natural hormones, such as estrogen, and interfere with the endocrine system’s function.
Research indicates that exposure, even at very low doses, can have biological effects. Studies have linked this exposure to reproductive health issues, including effects on fertility and sexual maturation. BPA exposure may also affect neurological development in infants and fetuses, and some human studies connect it to metabolic disorders and cardiovascular problems.
Current Regulatory Status of BPA in Cans
Regulatory bodies have taken different approaches to managing BPA exposure. The U.S. Food and Drug Administration (FDA) currently maintains that BPA is safe at the low levels found in packaging. The FDA’s position is based on its assessment that migrating amounts are too small to pose a health risk, and the human body metabolizes and eliminates BPA effectively.
Conversely, the European Food Safety Authority (EFSA) adopted a much stricter stance after its 2023 risk assessment. EFSA significantly reduced the tolerable daily intake (TDI) for BPA by 20,000 times, concluding that current average dietary exposure presents a health concern, especially regarding the immune system. This divergence led to differing regulatory actions, with the European Commission proposing a ban on most uses of BPA in food contact materials. Consumer pressure also caused a major industry shift, leading manufacturers to voluntarily eliminate BPA from packaging like baby bottles and infant formula cans, and then phase it out of most other food cans.
Developing BPA-Free Alternatives
The industry-wide move away from BPA has spurred the development of alternative linings to ensure food safety and shelf stability. Common non-BPA lining materials now in use include:
- Acrylic resins.
- Polyester resins.
- Polyolefins.
- Vinyl organosol lacquers or oleoresinous c-enamels, which are derived from plant resins.
The challenge is ensuring these new materials provide the same corrosion resistance and barrier protection as the original epoxy resins, especially for highly acidic foods. While these replacements are chemically different from BPA, the term “BPA-free” does not mean the material is entirely chemical-free. Some scientists voice concern over “regrettable substitution,” where a chemical with similar or unknown health concerns, such as other bisphenols like BPS or BPF, is used as a replacement.