By Barbara Kessler

The news on bisphenol A or BPA just doesn’t get better. The chemical, used to make plastic baby bottles and food can liners, could deliver a double-whammy to women, paving the way for breast cancer, and then boomeranging back to interfere with the treatment for cancer recovery.

A study by University of Cincinnati scientists released this week found that BPA exposure may reduce the effectiveness of chemotherapy treatments for breast cancer patients.

Researchers found that this man-made chemical – already implicated as a potential trigger in breast cancer because it is structurally similar to the estrogenic DES – induced a group of proteins in the body to protect breast cancer cells from the chemotherapy.

Resistance to chemotherapy is already a “major problem for cancer patients, especially those with advanced metastatic disease,” said UC’s Nira Ben-Jonathan, a professor of cell biology who’s been studying BPA for more than a decade.

Dr. Ben-Jonathan’s team discovered the BPA-chemotherapy problem by exposing human breast cancer cells to low levels of BPA, similar to those found in the blood of humans. The BPA mimicked estrogen, inducing the protein cells to protect the cancer cells.

Estrogen has been known to block chemotherapy treatment, but this new finding could help explain why some post-menopausal women, with lower levels of estrogen, suffer from chemotherapy resistance, Dr. Ben Jonathan said. Her study was underwritten by the U.S, Department of Defense, the National Institutes of Health and the Susan G. Komen Breast Cancer Foundation and is discussed in Science Daily.

BPA has been suspected of playing a role in a variety of health issues, acting as a hormone disruptor in children and adults and possibly inducing neurological changes in kids. Studies with rats and mice have shown changes in tissue that some believe presage breast or prostate cancer development.

Last month, an article published in the Journal of the American Medical Association, added another concern. It found that a group of adults with the highest levels of BPA detected in their urine were nearly three times as likely to develop heart disease and had twice the risk of diabetes compared with those who had the lowest levels of BPA.

In recent months, many medical and environmental science groups, notably the Washington-based Environmental Working Group, have been cautioning parents of infants to forego baby bottles made of polycarbonate plastic, and manufacturers began offering alternatives in glass or other types of plastic (look for the BPA-free label).

The problem with food cans, in which BPA is used within the epoxy liners to keep food from chemically eroding the metal casing, has been less publicized and there’s been little public response from manufacturers.

The EWG advises lowering exposure to BPA by simply avoiding products containing the chemical. Among those:

  • Hard, clear plastic polycarbonate baby bottles or sport water bottles. They can sometimes be identified by their plastic notation on the bottom of the bottle showing they’re made with #7 plastic.
  • Food sold in cans, and watching particularly acidic foods, like tomatoes, which may cause leaching from the BPA liner. Look for food in glass jars, or seek refuge in the produce section.
  • Soda in cans (The levels of BPA may be lower here, but the volume of consumption could be higher.)
  • Pre-mixed liquid baby formula sold in cans

The U.S. Federal Drug Administration has green lighted the current use of BPA in food cans, for instance, saying that the amount of the chemical ingested by humans is very small. But critics say the agency has relied on plastics industry-backed studies.

As cause for concern, scientists point to a 2004 Centers for Disease Control study showing that 95 percent of people tested had traces of BPA in their urine.

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