The words “BPA-free” have become a marketing fixture on water bottles, food containers and can linings worldwide. For many consumers, the label is reassuring: one worrying chemical removed, problem solved. But the science tells a different story. In most cases, BPA was replaced with a structurally similar compound called BPS, which acts on the same biological pathways in the body. The switch addressed a regulatory and reputational problem, not a safety one.
What is BPA and why did it get banned?
Bisphenol-A (BPA) is an industrial chemical used to make polycarbonate plastics since the 1950s. It appears in hard clear plastic bottles and containers, the epoxy resin linings of food and beverage cans, thermal paper receipts, dental sealants, and the coating on some water supply pipes. Its commercial usefulness comes from the same molecular property that makes it biologically problematic: it is chemically similar in shape to oestradiol, the primary human oestrogen.
BPA binds to oestrogen receptors in the body and triggers hormonal responses at very low concentrations, well below those traditionally used in toxicology testing. It is classified as an endocrine-disrupting chemical. Research has linked BPA exposure to reproductive dysfunction, altered fetal development, obesity, insulin resistance, cardiovascular disease, and hormone-sensitive cancers. The evidence accumulated over several decades. The European Union banned BPA in baby bottles in 2011 and in thermal paper in 2020. The US FDA banned it in baby bottles and sippy cups in 2012. Under consumer and regulatory pressure, manufacturers began switching to alternatives. BPS was the most widely adopted.
Enter BPS: the same problem in disguise
Bisphenol-S (BPS) is structurally very similar to BPA: both are bisphenol compounds built around two hydroxyphenyl groups. The switch from BPA to BPS was driven primarily by the fact that early safety data on BPS was limited, meaning manufacturers could truthfully claim the replacement compound had not been shown to be harmful. This is a fundamentally different claim from saying it is safe.
“BPA-free” on a product label tells you that bisphenol-A is absent. It says nothing about what replaced it. In most hard polycarbonate plastic products and in most can linings, the answer is BPS. BPS is also used in thermal receipt paper: studies have found BPS concentrations in receipts comparable to, or higher than, the BPA levels they replaced.
What the research actually shows
The body of research on BPS has grown substantially since its widespread adoption. A 2015 study published in the journal Endocrinology found that BPS disrupted reproductive cycles in animal models with effects comparable to those seen with BPA. Subsequent work confirmed that BPS binds to oestrogen receptors in human cell lines with similar affinity to BPA. A 2018 study found BPS detectable in the urine of 81% of sampled Americans, confirming widespread exposure through food contact materials and thermal paper.
Research from the University of California, Berkeley found that BPS alters hormone signalling in developing zebrafish embryos in ways that parallel BPA's effects. Studies have also suggested that BPS may have greater environmental persistence than BPA, meaning it accumulates in water systems over longer timescales. Some research indicates BPS may have more potent effects on thyroid hormone disruption than BPA. The compound is newer, the research base is thinner, and some effects may not yet be fully characterised. None of this is reassuring.
“BPA-free on a product label tells you one chemical is absent. It says nothing about what replaced it. In most hard plastic containers, the answer is BPS.”
Regrettable substitution: a recurring pattern
Toxicologists and environmental health researchers have a name for what happened with BPA and BPS: regrettable substitution. The pattern is consistent. A chemical compound is found to be harmful. Rather than redesigning the product or switching to a fundamentally different material class, manufacturers replace the compound with a close structural analogue that has not yet accumulated enough evidence to trigger regulation. The new compound eventually attracts research, that research identifies similar harms, and the cycle begins again.
The same pattern appears with phthalates: DEHP was restricted, replaced by DINP and DIDP, which were subsequently found to have similar endocrine-disrupting properties. With flame retardants, polybrominated diphenyl ethers (PBDEs) were phased out and replaced with organophosphate flame retardants, which have since accumulated their own adverse health evidence. Current chemical safety frameworks regulate compounds individually, which structurally encourages this substitution cycle. The European Chemicals Agency has begun addressing this with whole chemical class restrictions, but adoption is slow and enforcement is uneven.
The practical lesson for consumers is to stop evaluating safety at the level of individual chemicals. A product is not safer because it removed one compound from a class of compounds that share the same hazard profile. The question to ask is not “does this contain BPA?” but “is this product made from a material class associated with endocrine disruption?”
What to do
Switch to glass or stainless steel containers
Replace polycarbonate water bottles and food storage containers with glass or stainless steel. Neither material leaches bisphenol compounds or other endocrine-disrupting plasticisers. Glass is preferable for acidic foods. Stainless steel is more practical for transport.
Never heat food in plastic
Heat accelerates the leaching of bisphenol compounds and other plastic additives. Transfer food to a glass, ceramic, or stainless steel container before microwaving or reheating. Even plastics marketed as microwave-safe leach measurable levels of chemicals when heated.
Handle thermal receipts minimally
BPS-coated thermal paper receipts transfer the compound through skin contact, particularly on warm or damp skin. Ask for digital receipts wherever possible. If you must handle receipts, do not touch your face or food afterwards, and wash hands promptly.
Choose glass jars or cartons over canned goods
Can linings frequently contain bisphenol compounds, and the heat used in canning increases leaching. Where possible, choose products in glass jars or cartons. If canned goods are unavoidable, rinse the contents before eating. Some manufacturers explicitly label cans as bisphenol-free.