'Oestrogen soup' linked to cancer/Oral contraception linked to prostate deformities/ Plastics link to 'macho' female mice

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http://www.newscientist.com/article.ns?id=mg18725085.200

'Oestrogen soup' linked to cancer

 

16 July 2005 From New Scientist Print Edition. Subscribe and get 4 free issues

LONG-TERM exposure to oestrogen-like chemicals might increase the risk of breast cancer in women with a genetic predisposition to the disease. "For people who are susceptible, breast cancer might be sped up," says William Baldwin of the University of Texas in El Paso.

For nine months his team fed a chemical called 4-nonylphenol, which is found in drinking water, processed foods, plastics and paints, to mice with a mutation that makes them susceptible to breast cancer. Five out of the 13 mice fed a high dose of the substance developed breast cancer, compared with none of the 14 fed a lower dose and only one out of the 14 mice fed honey (Journal of Applied Toxicology, DOI: 10.10002/jat.1078).

"It was a little more potent than we thought," says Baldwin. Although the dose is probably higher than most people are exposed to, Baldwin thinks that other environmental oestrogens, such as bisphenol A, are likely to have a similar effect, so there is cause for concern about their cumulative long-term effects. "We are exposed to a soup of oestrogens," he says.

From issue 2508 of New Scientist magazine, 16 July 2005, page 19

 

 

 

 

Oral contraception linked to prostate deformities

http://www.newscientist.com/article.ns?id=dn7333

 

13:44 03 May 2005 NewScientist.com news service John Pickrell

 

 

 

 

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Oestrogen-like chemicals commonly found in oral contraceptives and plastic packaging could deform the prostate gland of human embryos, suggests a new study in mice. Deformities to the prostate gland have been linked to prostate cancer and bladder disease in later life.

The finding is significant because up to 3% of women taking oral contraceptive drugs become pregnant without their knowledge, and continue exposing the fetus to the contraceptive drug many months into pregnancy.

This is because the risk of pregnancy becomes higher when the drug is not taken diligently, but many women do not realise this, says study author Frederick vom Saal of the University of Missouri in Columbia, US.

Among the 60 million women using oral contraceptives in the US and Europe, the average number of missed pills is three per month, he says. This results in up to two million women taking the pill accidentally becoming pregnant each year.

Environmental pollutant

In order to test the effect of a typical oral contraceptive on the development of the embryo, vom Saal and his team gave pregnant mice the contraceptive ethinylestradiol. The dosage was scaled down to the mouse-equivalent of one-fifth of the normal human dose and was administered for five days.

They also exposed a group of mice to low levels of a similar oestrogenic chemical, bisphenol A - a common environmental pollutant found in polycarbonate plastics and the lining of food cans.

The researchers found a subsequent increase in the number and size of prostate ducts and a narrowing of the bladder neck in male mouse fetuses exposed to these chemicals.

The effect seen was similar to the deformities caused by diethylstilbestrol - a known teratogenic and cancer-causing chemical also tested by the team. That drug caused cancer and other reproductive organ abnormalities in children born in the 1950s and 60s after it was administered to their mothers while pregnant.

The researchers argue that the effect seen in mice - which could lead to difficulties with urination as well as prostate cancer - is a direct analogue of how these drugs affect the human reproductive system.

Synthetic hormones

“These chemicals [mimic] extremely potent synthetic sex hormones, strong enough to completely control an adult women’s reproductive system,” vom Saal told New Scientist: “The developing fetus is extremely sensitive to chemical disturbance…so exposing a male baby to them is a very bad idea.”

“These interesting results add to the evidence that these chemicals can damage human embryos,” comments endocrinologist Stephen Safe at Texas A & M University in College Station, US. Though more studies are needed to confirm the mouse strain tested is a good analogue of the human reproductive system, the findings justify a careful re-evaluation of the safety of these chemicals, he says.

On 28 April a legislative committee in California, US, passed a bill to ban bisphenol A from all products used by children aged three and under. Currently over two million tonnes of polycarbonate plastics containing the chemical are produced worldwide each year.

Journal reference: Proceedings of the National Academy of Sciences (DOI: 10.1073/pnas.0502544102)

 

 

Plastics link to 'macho' female mice

 

12:00 14 May 2006 From New Scientist Print Edition. Subscribe and get 4 free issues.

 

 

http://www.newscientist.com/article.ns?id=dn9156

 

WHEN does a female mouse behave like a male? When you give it small doses of bisphenol A, a chemical that mimics the hormone oestrogen. The "gender bender", which masculinises the brains of female mice, is the base chemical for making polycarbonate plastics, often used in bottles and food containers.

When Ana Soto and colleagues at Tufts University in Boston constantly infused bisphenol A into the tissue of pregnant and breastfeeding mice, the female pups displayed the masculinised effects. The doses were equivalent to concentrations found by the US Centers for Disease Control and Prevention in samples of human urine. "We're talking about environmentally relevant levels of exposure," says Soto.

The female pups of mice exposed to the chemical had half the normal number of neurons in an area which controls female reproductive cycles, the same number as males. They also performed more like males in a standard behavioural test (Endocrinology, DOI: 10.1210/en.2006-0189).

Steven Hentges of the American Plastics Council in Arlington, Virginia, points out that humans can metabolise bisphenol A, whereas the mice could not do this since the chemical was administered direct to tissue. "It makes you wonder if it's relevant to humans," he says.