First off, some of the test methods were ridiculous. The samples were stressed in UV light "by placing samples about two feet from a 254nm fluorescent fixture for 24 hours, simulating repeated UV stress by sunlight (e.g., water bottles) or UV sterilizers (e.g., baby bottles and medical items)" and by heat in an "autoclave (heat and moisture stress) by autoclaving at 134°C for 8 minutes, simulating moist heat stress in an automatic dishwasher".
Long-time reader of this blog know that that 254 nm may make a good jungle test, but it does not simulate sunlight. The results of this stressing need to be correlated to the real world or they are invalid. Would we be surprised that extracts are at higher than normal level?
The same is true of the autoclave exposure - maybe even more so. No dishwasher gets anywhere close to 134 oC - all the PE containers would be hopeless deformed. Again, would we be surprised that extracts are at a higher than normal level?
The authors lake make the unsupported assertion that all these mimics can be avoided. As support, the authors [*] have prepared samples that do not show estrogen-mimicking activity. Unfortunately, the details of the formulations are not disclosed. How can this get published? Can you go into the lab and reproduce these results? Isn't that the hallmark of a scientific publication? Furthermore, these samples were never tested for anything beyond their estrogen-activity (EA), as if that is the only concern that an engineer has when developing a food/beverage package.
But it gets worse when they then overplay their hand and draw this conclusion:
"Because additives comprise a small fraction (typically 0.1-1% by weight) of plastic resins and compounds, and because plastic resins and compounds using EA-free additives are processed during manufacture in a nearly identical manner as conventional resins and compounds containing chemicals with EA, the replacement of additives having EA with EA-free additives should have very little impact on the cost of the final product. Furthermore, EA-free additives have only a slightly higher or no additional cost compared to additives with EA, so that their cost impact is very small or non-existent."Not only are the conclusions not supported by the data, but the logic is filled with non sequitors. This all based on the word "should", as if that mere wish will make this come true. Anybody who thinks that the word "should" can be used to predict behavior is someone without real world experience. "Should" tells you how the world isn't, not how it is. "Should" won't get you FDA approval, EPA clearance, pay the bills, or keep the lights on. "Should" can get you a patent and a published article if the reviewers aren't following too closely.
Let's see these resins being used in real-world products, not just in manufacturing samples. Something that has to withstand the distribution and production cycles, something that has to meet clarity requirements, cycle times, and all the other expectations that consumers have.
And one last bit of advice on the business end: don't go around calling your materials as EA-free. As test methods become more sensitive, you may find that they aren't EA-free. Analytical chemists never say that something is "_____-free", only that it may be there below the detection limit. It's just a bit more sloppy science in a large pile.
[*] 4 of the 5 authors work for either of 2 companies, Plastipure and Certichem, companies owned by the last-listed author. The companies stated goals are to "focus on developing safe plastic materials and products" and to "provide highly sensitive & very reliable in vitro cell proliferation assays for detecting hormonal activity" respectively.
Updated. The conflict of interest is noted in the research paper.