{"id":6101,"date":"2017-01-23T16:05:15","date_gmt":"2017-01-23T21:05:15","guid":{"rendered":"http:\/\/blogs.edf.org\/health\/?p=6101"},"modified":"2017-01-23T16:05:15","modified_gmt":"2017-01-23T21:05:15","slug":"a-non-estrogenic-alternative-to-bisphenol-a-at-last","status":"publish","type":"post","link":"https:\/\/blogs.edf.org\/health\/2017\/01\/23\/a-non-estrogenic-alternative-to-bisphenol-a-at-last\/","title":{"rendered":"A non-estrogenic alternative to Bisphenol A at last?"},"content":{"rendered":"

Sarah Vogel, Ph.D.<\/a>,\u00a0<\/em>is Vice-President for Health.<\/p>\n

Last week a new study was published showing promising results for a non-estrogenic alternative to polymers based on bisphenol A (BPA) used to line the\u00a0 inside of food cans. \u00a0The paper,<\/a> in Environmental Science & Technology (ES&T), <\/em>evaluated the estrogenicity of an alternative to BPA\u2014 tetramethyl bisphenol F (TMBPF) \u2014 and its final polymer product developed by Valspar<\/a>, a major paint and resin company. The authors found that, unlike BPA and some of its analogs that have been used as substitutes, TMBPF exhibited no signs of estrogenicity.<\/p>\n

This was an unusual paper on a number of fronts\u2014how the material was selected, how it was evaluated and by whom.\u00a0 In this post I\u2019m going to explore who was involved, what testing was done and what this might mean for the BPA alternatives market.<\/p>\n

<\/p>\n

But first a bit of context because you may be asking, aren\u2019t there already non-BPA-based polymer alternatives for use in food cans? What about those cans that say \u201cBPA-free\u201d? The reality is that despite serious, decades-long concerns about the estrogenicity of BPA, the chemical continues to be widely used to make linings of food cans due to the considerable versatility of the material, which has made it challenging for alternatives to penetrate the market. \u00a0There are a few alternatives available but none have offered a total replacement of BPA-based coatings used in nearly all food cans today.<\/p>\n

The new research described in the ES&T <\/em>paper was funded by Valspar, which immediately raises concerns about conflicts of interest, given the considerable financial stakes it has in finding an effective and safer replacement to BPA. But here is where it gets interesting in terms of who was involved in this project and how conflicts of interests were managed.<\/p>\n

Who did the research?<\/strong><\/p>\n

To assess the estrogenicity of TMBPF, Valspar worked with leading researchers who have been publicly outspoken about the adverse health effects of BPA and other endocrine-disrupting chemicals. Dr. Ana Soto, the lead author, runs a laboratory at Tufts University which has been researching BPA and other endocrine-disrupting compounds for decades.\u00a0 And co-author Dr. Maricel Maffini, who also worked at Tufts in Dr. Soto\u2019s lab, has an extensive publication record on the adverse effects of BPA. One could argue that they have an interest in finding a safer alternative to BPA-based resins.<\/p>\n

What we know from the disclosure of competing financial interests included in the paper is that Valspar provided Dr. Soto\u2019s laboratory with \u201cunrestricted funds\u201d to conduct tests of the estrogenicity of TMBPF and the final polymer.\u00a0 Valspar also contracted with Dr. Maffini to serve as technical consultant on the project.\u00a0 In addition, a Valspar employee and a former Valspar employee were also co-authors.<\/p>\n

(For full disclosure on our part, Dr. Maffini is also a consultant with EDF.\u00a0 We would not financially benefit from the successful marketing of this material.)<\/p>\n

Why TMBPF? <\/strong><\/p>\n

The selection of TMBPF for evaluation arose from a reframing of the design problem.\u00a0 Rather than searching for a novel or alternative polymer material, the problem was turned on its head: can the same polymer be used \u2013 but employ a safer bisphenol building block? \u00a0More specifically, how could the highly effective 4,4\u2019-Methylenediphenol polymer chain used in food can linings be made without using an estrogenic bisphenol, like BPA?<\/p>\n

The authors note that they selected TMBPF because predictive modeling suggested it was unlikely to bind to the estrogen receptor.\u00a0 They also note that TMBPF was preferred because it could be employed in a two-step process that created an intermediate and hence avoided TMBPF being directly used in the final polymerization process; this would reduce the likelihood of unbounded monomer remaining in the final product\u2014a problem with the BPA-based polymers.<\/p>\n

What testing did they do? <\/strong><\/p>\n

The first step was to evaluate the migration of TMBPF from the polymer coating in order to assess the likelihood of exposure in food.\u00a0 No migration of TMBPF was detected above the level of detection of 0.2ppb well below reported levels of BPA migrants from epoxy can linings<\/a>.<\/p>\n

The authors then selected a series of in vitro <\/em>and in vivo <\/em>tests that assessed TMBPF\u2019s and the final polymer\u2019s estrogenicity. The in vitro <\/em>tests included the following:<\/p>\n