This study was conducted by a team of researchers, including Dr. George Bittner, Professor of Neurobiology, University of Texas, Austin. info%3Adoi%2F10.1289%2Fehp.1003220. When asked for information regarding plastic wine closures, one of the research team members, Stuart Yainger sent us this reply:

“The plastic  corks tested were Nomacorcs, sourced from a winemaker supply house (Winemakers Depot). We tested both the outer skin (which is principally a TPV material, similar to Sarlink) and the inner foam (which is principally a metallocene polyethylene, similar to Affinity). Each material was extracted for 72 hours at 37°C in ethanol and in water, then the extracts analyzed for estrogenic activity (EA) in accordance with the procedures outlined in our paper in “Environmental Health Perspectives” (Env Health Perspec 119:7, pp 989-996, July 2011). The cork components were extracted in “as supplied” condition and not stressed or chemically altered.

Our assay procedure utilizes proliferation of human breast cancer cells as an indicator of estrogenic activity. All experiments utilized negative and positive controls, as well as confirming estrogenic response by inhibition with antiestrogen ICI.

EA test results are expressed as %RME2, with 100% RME2 being the in vitro response amplitude to 17 beta estradiol, the natural human estrogen. Results over 15% are considered significant. The Nomacorc test results were 65%RME2 for the core and 42%RME2 for the skin. These numbers are quite high. We have repeated the tests and are confident that the results are correct.

When given the choice between a closure that has a potential health risk, a product that is not sustainably sourced, biodegradable, uses more energy to make and releases more green house gasses than natural cork, why would a winery or wine consumer choose plastic?