Monday, October 1, 2012

Is Tritan estrogenic?

I've always found the BPA issue to be a bit of a tempest in a teacup. [That said, I made the decision in my family to go with glass bottles for our children (me a chemist, my sainted wife a health care professional -- we're not going to drop the bottles.) All the kid stuff is BPA-free, so actions speak louder than words, ya know?]

Anyway, I've been following the Eastman Chemical versus CertiChem/PlastiPure kerfluffle with some interest, which is why I'm bringing this article from this week's Chemical and Engineering News by Alex Tullo:
An obscure conflict over a plastic is raising big issues in the field of material safety assessment. Two related Texas-based firms, PlastiPure and CertiChem, are accusing Eastman Chemical of trying to “squelch” science they say shows that Eastman’s Tritan polymer exhibits estrogenic activity. In turn, Eastman charges that the two firms are trying to malign its product for commercial gain. 
The controversy hits at one of the selling points of Tritan—that it is free of bisphenol A, an estrogen-disrupting compound. Tritan is a copolymer of dimethyl terephthalate, 1,4-cyclohexanedimethanol, and 2,2,4,4-tetramethyl-1,3-cyclobutanediol. Eastman designed it as a clear, tough, dishwasher-safe polyester that could compete with polycarbonate, which is made with bisphenol A. 
Eastman introduced Tritan in 2007, just when the controversy over bisphenol A came to a head and retailers led by Walmart were banning polycarbonate in baby products, such as bottles and sippy cups. Tritan got a lift as a ready replacement, but the claims by PlastiPure and Certi­Chem now pose a challenge to its success. 
CertiChem, founded by George Bittner, a professor of neurobiology and pharmacology at the University of Texas, Austin, offers third-party testing of materials to detect estrogenic activity using an MCF-7 cancer-cell-line assay. Chemicals that bind to estrogen receptors in the cells cause them to proliferate. PlastiPure, also founded by Bittner, develops plastic compounds that are free of estrogenic activity, according to this test. PlastiPure’s work has received support from the National Science Foundation and the National Institutes of Health.
I've always wondered what could be estrogenic about Tritan -- neither cyclohexanedimethanol or a cyclobutanediol moiety could be problematic. (I'm pretty sure I got my wife a Tritan water bottle in the last couple of years...) But the terephthalate might be an issue? Hard to say.

Also, I'm less than convinced by CertiChem's technique of calling just about all plastics estrogenic by using the MCF-7 assay. But I'm no endocrine scientist... Readers, what do you think? 

10 comments:

  1. If dimethyl terephthalate was an issue people would probably already be complaining about PET bottles.

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  2. CJ,

    I've argued in the past that the CertiChem approach is utterly bogus.

    For starters, they exposed the plastic to 254 nm UV light and then looked for estrogenic activity without identifying whether or not the responsible chemical was in plastic originally or not.

    254 nm light is going to be doing a whole lot of crazy chemistry on any organic material, creating a whole new mix that doesn't resemble much of the starting material. Is it any surprise that they guys find that polyethylene, polypropylene and just about anything else as having estorgenic activity?

    Whoever reviewed the paper knew NOTHING about accelerated aging of plastics.

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    Replies
    1. 254 nm UV light is present in sunlight. Plastic bottles are exposed to sunlight in normal use. It is therefore perfectly reasonable to test for estrogenic activity in plastic which has been exposed to 254nm UV.

      Indeed, the tests would be irrelevant if they did not.

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    2. This comment has been removed by the author.

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    3. The previous comment is uninformed. Below roughly 32km in altitude zero 254nm light is passed through the atmosphere. Were it, we'd all die. http://en.wikipedia.org/wiki/File:Ozone_altitude_UV_graph.svg

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  3. So what safe plastics did they identify according to their tests?

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  4. Has there been any update to this debate? Thank you for sharing this article.

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    Replies
    1. Not really, although the lawsuit went to trial and the jury found in favor of Eastman: http://www.austinchronicle.com/news/2013-08-02/eastman-wins-jury-still-out-on-plastic/

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  5. The fact that the founder of a company that test the health hazards of other manufacturers plastics is ALSO the founder of a company that aims to develop (and sell) plastics with reduced health hazard is such a flagrant conflict of interest that its shocking that anyone would take his findings as objective and unbiasised.

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  6. In a follow-up study, some of the Tritan resin samples leached chemicals with estrogenic activity even without being stressed by heat or UV:

    "The 200-plus samples of Tritan resins that were tested consistently leached estrogenlike chemicals after being exposed to a type of ultraviolet ray found in sunlight (UVA) and another kind that some parents use to sterilize baby bottles (UVC). In some cases, samples that hadn't even been exposed to UV light also seeped estrogenic compounds."

    From http://www.motherjones.com/environment/2014/11/tritan-bpa-free-plastic-styrofoam-estrogen

    The follow-up study itself will soon be published in Environmental Health.

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