Monday, March 02, 2015

Is Tritan Plastic Free of Estrogenic Activity? (Part 1)

[Note: This is the first part of a 3-part series taking a critical look at the work of University of Texas - Austin neuroscience Professor George Bittner regarding estrogenic activity in plastics. Part 1 here gives general criticisms of his work in this area, while Part 2 and Part 3 which looks critically at the results of a pair of 2014 publications.]

It's been a while since I've discussed the work of neuroscientist Prof. George Bittner who claims to have found estrogenic activity (EA) in a wide range of plastic materials, not just polycarbonates that are known to show EA due to the residual bisphenol A (BPA) that resides within them, but polyethylene, polypropylene and more. Pretty much all plastics were implicated, which was quite shocking. This paper came out back in 2011 and he worked up quite a publicity train of hype trumpeting the results in interviews with major news outlets such as the New York Times. Not only was this PR tour driven by his "results", but also by the fact that he owns two companies, Certichem and Plastipure, which are involved in running these types of tests and then supplying plastics that pass the tests, respectively. So you could say there was a potential conflict of interest.

I (and other researchers) had no problem in quickly finding major flaws in the work. His work involved "stressing" the samples, and it was these stressed samples that showed high levels of EA. But there were significant problems with his stressing protocols, namely that he had no controls at all. While Bittner would argue that an unstressed sample would be a control, it isn't. Whenever any is running accelerated "stressing" of plastics (more commonly known as accelerated aging), you need to have control samples that are undergoing natural aging. Without those naturally aged controls, you have no idea if the stressing is in fact aging the samples properly or if it is producing unnatural results.

The classic example are chicken eggs. Heating up a dozen of them in boiling water for 10 minutes is not going to give you a batch of new chicks. That's because excessive heat accelerated undesired chemical reactions, reactions that don't occur in natural aging. Heating and cooling the eggs only within a very-narrow temperature-window will speed-up/slow-down the hatching. Anything else will produce unnatural results.

Or think of it this way, in terms of an imaginary movie script. The bad guys want to know where the good guy keeps some unknown valuable item that they are looking to steal. The natural-aging analogy would be for the bad guys to tail closely the good guy. The accelerated-aging analogy would be for the bad guys to be driving faster ahead of the good guy, occasionally looking in the rear view mirror to see that he's still there. If they correctly predict the good guy's route, they will get to the valuable item first. But if they look back and see that he's turned onto a different route, then the bad guys need to turn around, go back to that turning point and continue. It would be crazy for the bad guys to drive quickly without ever looking back at the naturally-aged control (i.e., the good guy). Such a scene would mean only that they will get somewhere fast, but it may or may not be the right spot at all. Yet that was what Bittner was doing. Going somewhere fast, but with no idea or proof that the final result was correct at all.

And this is not just me saying this. Take a look at these three pictures.
Outdoor Weathering Facility
Miami FL, USA

Phoenix AZ, USA
Magdeburg, Germany
These are all large outdoor weathering facilities and there are dozens of others from around the world that are not shown. If accelerated aging was merely a matter of counting photons, these facilities would not be needed at all.

For Bittner's research, it was even more important than usual to have a proper control as his test methods never identified what specific chemicals were showing the EA. And so it was impossible to know whether it was one or more chemicals that were created during the stress that didn't even exist in the unstressed plastic. Or if the the chemicals would ever develop under natural aging conditions.

Beyond lacking in a naturally aged control, Bittner's stressing protocols were extreme and therefore all the more likely to produce erroneous results. He simulated natural UV aging by exposing the plastic to 254 nm UV light, light that is not naturally occurring on earth, light that is known to be highly energetic and destructive to organic materials. Hence it's use as a germicidal lamp. Photons with a 254 nm wavelength chop up chemicals like a wood chipper chops wood, and all little bits are new chemicals that weren't there before. (Hence my very strong concern for a naturally-aged control.) Similarly, Bittner simulated a dishwasher with an autoclave. (Huh? Don't they have dishwashers in Austin, Texas?) An autoclave produces much higher heat than any dishwasher and it also doesn't "wash" anything. A dishwasher loaded with soap would wash away chemicals that diffuse to the surface which would decrease the chance of producing positive EA results. Similarly, Bittner ran a bunch of plastic samples repeatedly through a microwave. While this appears to be a realistic procedure, very few people run the same container 10 or more times through the microwave without washing it in between uses. And such a washing step would reduce any EA chemicals at the surface. You can now see that these "stress" tests were really just doing a bunch of extreme things to plastic samples that are not correlated to realistic conditions at all. I stated all of this in earlier posts back in 2001. (And it seemed to have had an effect as you will see in Part 2 of this series of posts.)

The accusations made some people upset, including Eastman Chemical. Eastman makes the Tritan family of plastics and has been pushing them heavily as a BPA-free alternative to polycarbonate. Bittner accused Tritan of showing EA, Eastman disagreed and the gloves came off, only being put back on after a jury in Texas agreed that Bittner's claims were invalid. Bittner appealed and lost there too.

Bittner has not given up the fight however. He published two new articles on the same subject matter late last year (which I will criticize wholeheartedly in parts 2 and 3), and is still making interviews, such as a recent one to National Public Radio.
"...Bittner's companies have changed their tactics a bit, says Mike Usey, the CEO of PlastiPure. 'We don't talk about Tritan, or Eastman, in a commercial context concerning the testing results that we have,' he says. 'But that doesn't limit our discussing our research in a scientific context.' That means Bittner and his companies are getting their message out by publishing scientific papers about estrogenic plastics that specifically mention Tritan and products made with it."
While they have changed their tactics on the PR trail a bit and are very careful in their new papers how they mention Tritan, they haven't changed their research tactics. They are still lacking in proper controls, and worse yet, they ignorantly continue to find new ways to abuse plastics without merit or reason, thinking that they are proceeding just fine. Bittner and company may well be fine neuroscientists, but they know next to nothing about polymer chemistry and processing plastics.

A leopard cannot change its spots.

Previous Years

March 2, 2012 - Cancelling a Stink with another Stink?

March 2, 2011 - Nonlinearity in Rheology - Be Afraid, Be Very Afraid

March 2, 2010 - Living without Plastics?

March 2, 2009 - Polymers and their Solubility

March 2, 2009 - Mylar - What it Isn't


Anonymous said...

We do accelerated aging testing all the time in my lab on agrochemical suspensions and we always tell the customer that there is no guarantee they will give realistic results. Of the samples that I have actually follwed to the finish of normal aging, many of them do NOT give the same results as the accellerated aging tests.

John said...

For some reason, people think that they can just count photons and match them up. If only it were that simple.

It really isn't any harder to do the same with temperature exposure, since the Arrhenius equation is well known, but that never seems as popular (thank goodness).