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Aug 272010

From Green Right Now Reports

Studies with lab animals have shown that BPA, the chemical found in certain clear plastics, can disrupt developing endocrine and hormone systems.

A new study with humans suggests that BPA exposure also affects mature hormone systems. Researchers looking at a group of 715 Italian men, ranging in age from 20 to 74, found subtle but measurable differences in testosterone levels, with men registering higher BPA levels also showing an uptick in hormone levels.

The group of researchers, led by the Peninsula Medical School and the University of Exeter, found that higher daily BPA exposure (as measured in urine) was “statistically associated with endocrine changes in men, specifically small increases in levels of testosterone in the blood,” according to a news release on the peer-reviewed research which is published in the latest issue of Environmental Health Perspectives.

BPA, found in polycarbonate plastic, resin liners of food cans and other containers and products, is known to mimic estrogen in the body, thereby disrupting hormone level signals in test animals. Studies have found that BPA can affect thyroid function, alter pancreatic beta-cell function and possibly play a role in cardiovascular disease.

The researchers consider this new research groundbreaking because it looks at how hormone levels are affected by every day exposures to BPA. The daily exposures of the test group ranged from about 5 micrograms per day to 8.9 micrograms.

The higher testosterone levels were not large, but were significant because they seem to confirm that BPA in the body does disrupt hormones, said Professor Tamara Galloway of the University of Exeter.

“The circulating testosterone concentrations we measured were still within a normal range for healthy men, but were statistically higher for men with higher BPA in their urine. The jury is still out on the general health effects of testosterone and how it impacts on other common diseases, we didn’t specifically measure fertility, for instance, so can’t comment on that aspect,” she said.

“BPA has been classed as a ‘hormone disruptor’ for many years, but until now most of the evidence has come from laboratory or animals studies,” Galloway added. “Here we have shown for the first time that higher exposure to BPA is associated with changes in circulating hormone concentrations in normal, healthy adult men.”

Now research needs to look at how this happens, and the potential effects on human health.

Oct 102008

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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