Environmental Factor

February 2011


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Are plastics without estrogenic-active compounds possible?

By Robin Arnette
February 2011

George Bittner, Ph.D.

Bittner titled his talk, "Most Plastic Products Release Estrogenic Chemicals: A Potential Health Problem That Can Be Solved." He believes the issue of EA in plastics is something that could be fixed, if more people were aware of the data. (Photo courtesy of Steve McCaw)

Raymond Tice, Ph.D.

Tice has held a series of seminars on new medium- and high-throughput screening methods. (Photo courtesy of Steve McCaw)

Diane Spencer and Frank Johnson, Ph.D.

Report on Carcinogens Health Scientist Diane Spencer (http://www.niehs.nih.gov/research/atniehs/dntp/roc/staff/spencer/index.cfm) and Research Geneticist Frank Johnson, Ph.D., conferred during the question and answer session of the seminar. (Photo courtesy of Steve McCaw)

Some plastic products that previously contained bisphenol A (BPA), a chemical used to make polycarbonate plastics and epoxy resins, are now made without the chemical, due to public concern about BPA's estrogenic activity (EA) and its potential ability to interfere with the body's endocrine system and produce adverse physiological effects. Yet, according to research performed by George Bittner, Ph.D., and his colleagues at CertiChem (http://www.certichem.com/) Exit NIEHS and PlastiPure (http://plastipure.com/) Exit NIEHS, almost all commercially-available plastic products, including those sold as BPA-free, leach chemicals that exhibit detectable EA.

Bittner detailed the science behind this conclusion and its potential for helping chemists and engineers develop new and competitively priced EA-free plastics for consumers at a recent seminar held at NIEHS on Jan. 14.

Bittner (http://www.biosci.utexas.edu/neuro/GeorgeBittner/index.html) Exit NIEHS, a professor of neurobiology at the University of Texas at Austin and an NIEHS grantee (see text box), had CertiChem and PlastiPure staff purchase several types of plastics, such as water and soda bottles, food baggies, and deli containers, and sorted them by retailer, product type, flexibility, resin type, and whether they contained BPA. In addition, some of the pieces were microwaved, autoclaved, or subjected to UV light to simulate the stress that people place on plastic items.

Team members took a gram of each of the stressed or unstressed products, cut them into 4 millimeter squares, and extracted the material in 1 milliliter of saline or 95-100 percent ethanol. To determine EA, they evaluated the ability of the extracts to stimulate the growth, or inhibit the ability of estradiol to stimulate the growth, of MCF-7 cells, a human breast cancer cell line with an endogenous estrogen receptor (ER). Positive responses were verified as being ER-specific. Bittner obtained some astonishing results.

"No matter what type of extract is tested, the majority of the plastic products have EA," he noted. "In fact, many BPA-free products release chemicals that have a greater total EA than BPA-containing products."

Chief of the Biomolecular Screening Branch (BSB) Raymond Tice, Ph.D. (http://www.niehs.nih.gov/research/atniehs/labs/bmsb/), served as host of the seminar and echoed Bittner's conclusions. "Clearly, BPA is not the only estrogenic compound in plastics commonly used in the food industry," Tice noted. "So, the goal of the plastics industry should be to formulate containers that are free of such activity rather than free of BPA only."

Science can lead to entrepreneurial opportunities

According to Bittner, during the production of standard plastics, manufacturers start out with a monomer, or a set of monomers, and then add other chemical agents. "After stress, many of these individual additives can leach out and display EA, so the key to making EA-free products is to find chemicals that don't exhibit EA even after stress," Bittner maintained. "The additional cost of making EA-free plastics is not high, typically 1 to 10 percent, when EA-containing or EA-free products are made in equal amounts. Most of that cost is attributable to testing the products to ensure they remain EA free."

With the addition of polymer chemists to the group, Bittner's research team was able to find several EA-free formulations for both soft and hard plastics. The work led to the creation of two companies - PlastiPure, which produces plastic containers using these plastics, and CertiChem, which tests for EA.

Alex Merrick, Ph.D. (http://www.niehs.nih.gov/research/atniehs/labs/bmsb/moltox/index.cfm), a BSB molecular toxicologist, thinks that the MCF-7 assay used in the testing "could potentially be used to monitor the safety of existing plastic products or possibly guide us in the search for newer, safer plastic products."

Bittner's results are promising, but more work needs to be done, such as having outside testing performed on his EA-free products. Nevertheless, the development of EA-free plastics is an important step.

NIEHS Grants

Title: Estrogen free Polymer Formulations for Food Packaging and Baby Products (http://tools.niehs.nih.gov/portfolio/index.cfm?action=portfolio.grantdetail&grant_number=R44ES016964)
Principal Investigator: Stuart Yaniger
Institute Receiving Award: PlastiPure, Inc.
NIEHS Program Administrator: Daniel Shaughnessy

Title: A Hard and Clear, Estrogen-Free Replacement for Bisphenol-A Based Polycarbonates (http://tools.niehs.nih.gov/portfolio/index.cfm?action=portfolio.grantdetail&grant_number=R43ES018083)
Principal Investigator: Daniel Klein
Institute Receiving Award: PlastiPure, Inc.
NIEHS Program Administrator: Daniel Shaughnessy



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