During the chemical process of polymerisation, bisphenol A (BPA) reacts and becomes firmly bound into the structure, thus actually building the polymer material.
More than 99% of all BPA produced worldwide is immediately converted into polymers. However, like with any chemical process, when using sofisticated measuring methods it will be possible to measure technically unavoidable trace levels of BPA (so-called free or residual BPA) in the final polymer .
One of the reasons polycarbonate is selected as material of choice in many food contact applications is its high thermal and chemical stability and the fact that it is virtually unbreakable. There has been extensive scientific research to examine whether such trace levels of BPA can subsequently "migrate" from polycarbonate plastic and epoxy resin products, and whether this poses any risk to human health.
Several high quality migration studies on BPA, which included daily use conditions such as heating, microwaving, dishwashing-mashine washing, rinsing, sterilising, have repeatedly shown that migration from BPA-based polycarbonate is extremely low; it is far below the safety levels set by the authorities and does not pose a health risk to the consumer under normal handling and use of the products.
The amount of free BPA in the polymer does not play a key role in the question of BPA-migration. This is because the dominant mechanism responsible for the release of BPA from the polymer surface into the contacting aqueous liquid is hydrolysis, not the amount of free BPA monomer (BPA residual). Studies have repeatedly shown that actual migration of BPA from BPA-based material such as polycarbonate is extremely low.
For example, a person weighing 60kg would have to consume every day of his/her entire life more than 600kg of food or drink that was in contact with polycarbonate, only to reach the level established as safe by the EFSA.
The body of accepted science therefore comes to two simple conclusions with respect to polycarbonate and epoxy resin:In fact, scientific studies have proved that trace amounts of BPA that might enter the human body are rapidly "metabolised" into an inactive kind of sugar, which is excreted from the body (within 24 hours) with no detrimental health effect.
With this understanding of the metabolic processes in the body, and after evaluating the available data on the realistic, extremely low BPA exposure, the regulatory authorities in Europe, the US and Japan have concluded that the use of polycarbonate plastic in applications that come into direct contact with food poses no concern, including when heated. This includes updated views on BPA published in August 2008 and 2010 by the European Food Safety Authority (EFSA) and the U.S. Food and Drug Administration (FDA).
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