April 27, 2004

High performance testing for bisphenol A

Several weeks ago, Watabe et al. published an article in the Journal of Chromatography on ultra-low level detection of bisphenol A (BPA) in environmental water [1]. BPA is a known endocrine distruptor and the center of brewing controversy regarding the use of polycarbonate material. Watabe et al. implemented high-performance liquid chromatography (HPLC) to achieve a sensitivity of 0.36 ng/L. This method was used to probe environmental water and purified water samples containing 2-70 ng/L of BPA.

The article itself is quite in depth, and worth a bit more reading. One thing that piqued my interested while skimming was

For ultra-low concentration of BPA analysis, BPA contamination from manual pretreatment procedures as well as adhesive for fixing needle of manual syringes affects the determination seriously. This means manual syringes cannot be applied to BPA microanalysis. To obtain reliable quantitative results at ppt concentration level, a column switching auto pretreatment system is essential.

Even employing this HPLC system, we unexpectedly encounter serious contamination problem due to BPA existing in purified water. A water purification system cannot remove BPA completely. A few ng/l level of BPA contamination often found in the purified water is not negligible and the contamination level varied daily. Consequently, there is no reliable way to correct a degree of contamination by calculation.

We have to obtain BPA-free water for preparing BPA standard solution otherwise reliable calibration curve cannot be created. BPA-free water was obtained by filtrating the purified water through Empore disk. Then the contamination was suppressed below the detection limit afforded by this HPLC system. Standard aqueous solution of BPA at 1, 10, and 100 ng/l were injected repeatedly (n=5) to estimate the repeatability of peak area and the results were shown in Table 1. A linear calibration curve with a correlation coefficient >0.999 was obtained. The recovery at 100 ng/l was 100.5% and even a trace of leaking and/or carry-over of BPA was not observed at same concentration. The detection limit estimated by utilizing standard deviation of y-intercept of calibration curves was 0.36 ng/l, which is quite low concentration.

[1] Y. Watabe, T. Kondo, M. Morita, N. Tanaka, J. Haginaka and K. Hosoya, "Determination of bisphenol A in environmental water at ultra-low level by high-performance liquid chromatography with an effective on-line pretreatment device," J.Chromatogr.A, vol. 1032, pp. 45-49, Apr 2. 2004.

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April 23, 2004

Vita-mix container

I sent an inquiry to the Vita-mix folks regarding our blender's polycarbonate container after reading a few articles on chemical leaching from polycarbonate materials. A swift response:

Dear Tim:

In response to your inquiry, the polycarbonate container is made from LEXAN and is approved by the FDA.

The information you are referring to is most likely from the vom Saal study. The study has not been replicated in any larger studies and when you do not see the effects, it certainly casts doubt on relying on one study and ignoring the larger ones.

George Pauli, director of the product policy at the US FDA agency said the agency is following the low dose issue and has seen no reason to take any actions addressing the bisphenol A issue. (GE - letter dated /6/8/99)Pauli said that bisphenol A leaches from polycarbonate baby bottles only under exaggerated conditions. If you heat a bottle with heat and liquid long enough, you can reverse the polymerization to a certain extent. He said that the testing conditions used by Consumer Union (see E/E Letter Vol. 5, no. 8 & 5) which included boiling bottles for 30 minutes, are not realistic. Additional information can be found on the American Plastics Council web site at www.plasticsinfo.org

I hope this information helps to identify your concerns. I would suggest not heating the milk in the polycarbonate container if you are concerned about your safety. If you are blending the soy milk in the container until it heats, I would blend the soy milk and then heat it on the stove.

Sandy Ventimiglia
Customer Service Manager
Vita-Mix Corporation
8615 Usher Rd.
Cleveland, OH 44138-2199
1-800-848-2649 ext. 5304

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Plastics and food

Be careful with what kind of containers you use to store and heat food. Sonja has been doing a lot of research on plastics over the last few days. You might wonder, if the type of plastic, e.g., #2, #3, #4, makes any difference, or even what they are. It does. Chemicals can leach from plasticware. She sent me two links that I found facinating if not slightly shocking.

  1. Shopper's Guide to Plastics & Food: Alternatives to the Problem Plastics
  2. Shopper's Guide to Plastics and Food
Biggest no-no? Polyvinyl chloride, most often found on plastic wrap. Yes, that plastic wrap. Guess who makes my Costco-purchased stretch-tite plastic wrap? Polyvinyl Films, Inc. Check out the PlasticProducts at a Glance chart for plastics found in different brands.

Now, the question is, how much of this is hype and how much of it is substance? More on this to come...

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