BPA is used in the production of two food contact materials: epoxy resins and polycarbonate plastics. Whilst it has been approved by regulatory agencies for use in food contact materials, there has been growing public concern about potential “migration” or “leaching” of BPA from food contact materials into food and drinks. You may have seen articles in the media about this and have asked yourself questions such as: Does this really happen and is it dangerous? Why is BPA actually present in food contact materials? Or, why is it not being replaced by other substances?
What does this leaching entail and is it dangerous?
During the production of polycarbonate plastic or epoxy resins, the BPA molecules are firmly bound, interlinked with each other and incorporated into the polymeric structure of the plastic itself. BPA is transformed into a new substance, i.e. polycarbonate. However, like with any other material (be it others plastics, glass, metal, or ceramic), there is some potential for small amounts of contained substances to migrate. In the case of epoxy resins used in cans or polycarbonate plastic used for example in bottles, there is indeed also the potential for extremely small amounts of BPA to migrate.
It is however important to note that when small amounts of BPA migrate into food or drinks and are ingested, our bodies are fully capable of processing the substance. Most of it is absorbed through the intestinal wall and converted to biologically inactive substances. Any remaining BPA that was not converted through the intestines gets converted to that same biologically inactive compound in the liver. The inactive compound is eliminated from the body within one day through urine. Humans of all ages, even premature infants, are able to process BPA so that it does not accumulate in the human body.
Whilst our bodies are capable of processing the substance, there are of course limits to it (as with water, vitamins or salt). In order to ensure that we can continue to safely enjoy our food and drinks, risk assessment authorities carefully evaluate exposure routes and determine the Tolerable Daily Intake (TDI) and corresponding safe migration levels for food contact materials.
Why is BPA actually used for food contact materials?
Despite the fact that migration levels are safe and our bodies are fully capable to process the substance, you may wonder why BPA is actually being used in food contact materials and why it is not being removed or replaced by another substance. BPA-based polycarbonate and epoxy resins are extremely durable while remaining light weight. They offer high impact resistance, can sustain numerous sanitation methods and therefore be used safely for many years. Heat resistance is another great benefit which is particularly essential in applications that require good hygiene conditions. It is this combination of characteristics that is specific to BPA-based polycarbonate and epoxy resin.
So BPA cannot simply be removed. But why is it not being replaced by an alternative substance that offers the same benefits? Well, there is currently no other substance commercially available that would offer the same benefit profile. In addition, coming back to the issue of understanding the properties and exposure scenarios of a substance, BPA is one of the most researched and well understood substances. Possible alternatives have not been tested to this extent and their toxicity is not well known. This could mean that a well understood substance could be replaced with an unpredictable risk.