Bisphenol A (BPA) is a chemical used in the manufacture of polycarbonate plastics (e.g. Lexan) and in epoxy resins. Trace BPA contamination of food products has recently been of concern because BPA is thought to be a weak endocrine disruptor. That is to say it has measurable female sex hormone (i.e., estrogenic) activity. Environmental estrogens are believed responsible for declines in human sperm counts.
Polycarbonate is a clear plastic not often used in food packaging, but epoxy resins are often found in the interior container coatings in food and beverage cans--used to protect the flavor of the food and to prevent corrosion of the container especially by acidic foods. Bisphenol A based epoxy resins are approved for this use under FDA regulations, i.e., 21 CFR.
Epoxy resins are made by the reaction of bisphenol A with epichlorohydrin. The product, often called bisphenol A diglycidyl ether (and low molecular weight oligomers) are commonly used epoxy resins. These are the work horse epoxy resins best known for chemical resistance and corrosion resistance. They are not noted for weather resistance, and hence are often used in primers and then topcoated for exterior use in paints. (They are also used in adhesives, in potting compounds, and in graphite and fiberglass composites.)
It should be noted that the chemical stability of the ether linkage makes it unlikely that cured epoxy resin is degraded to bisphenol A. More likely traces of unreacted BPA remain in the finished resin that can later be leached out of the cured coating or plastic.
Companies are working hard to find suitable replacements for bisphenol A in container coatings. An article in the Feb 11, 2013, issue of C&EN, provides an overview of the players, which may be of interest as investment opportunities.
Devoe-Reynolds (Epirez brand name), a small paint company in Louisville, KY, was a early player in the development of epoxy resin technology. Ciba-Geigy (Araldite), Shell (Epon) and Dow Chemical were early majors. The Araldite line was sold to Huntsman; the Epon and Epirez lines to Momentive.
The C&EN article lists Valspar, PPG, Rhodia (now Solvay), Akzo Nobel, Eastman Chemical, Cytec, and Dow Chemical as companies working to develop alternative technologies. Many expect the low cost high performance profile of bisphenol A epoxies will be hard to match. And all require FDA approvals, which may require time to complete.
The Wall Street Journal issue of Feb 16, 2013, reported that a study sponsored by EPA found that levels of BPA found in humans are far below the no effect level established in tests. As this is the standard for food use of chemicals, the article implies that concerns about BPA contamination are exaggerated. []
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