Deep in a laboratory freezer, 100,000 vials of blood have been frozen for the better part of five decades.

For scientist Barbara Cohn, it’s a treasure trove. Collected from more than 15,000 San Francisco Bay Area women after they gave birth in the 1960s, each vial of blood holds a woman’s lifetime of secrets.

Scientists say these vials could help them unravel one of the most enduring medical mysteries: Why do some women, with no family history, develop breast cancer?

The blood bears the chemical signature of environmental pollutants, some long banned, that the women were exposed to decades ago. Cohn, who directs the research in Berkeley, Calif., believes these early-life exposures may hold the key to understanding a woman's risk of breast cancer today.

The women's blood is being tested for traces of dozens of pollutants – used by industry and found in many consumer products – that can impersonate estrogen and other hormones. The theory is that early exposure to these chemicals, even before birth, inside the mother’s womb, may fundamentally alter the way that breast tissues grow, triggering cancer decades later.

Cancer patients and their doctors have long puzzled over what factors in a woman’s environment may raise her risk of breast cancer. One of every eight women in the United States is diagnosed with breast cancer during her lifetime, with more than 232,000 new cases diagnosed yearly, according to the American Cancer Society. Only five to 10 percent can be accounted for by genetics; other known risk factors include age, obesity and low physical activity.

Earlier this month, a science advisory panel urged the federal government to fund more projects aimed at uncovering the environmental causes of breast cancer because eliminating these factors may provide the greatest opportunity to prevent it.

It’s particularly vexing for scientists because it’s difficult to unlock a woman’s exposures during her most critical times for breast development: in the womb and during puberty and pregnancy.

“As researchers looking at adult outcomes of disease processes such as breast cancer, one of the biggest challenges we face is trying to get a handle on prenatal exposures and what is going on in the prenatal environment,” said Shanna Swan, an environmental health scientist at Mount Sinai School of Medicine in New York.

Many scientists have been looking for connections between various environmental exposures and the disease – with mixed results. Some findings suggest links to a few chemicals, including the banned pesticide DDT. But others have found no link.

For example, experts from the American Cancer Society, reviewing previous studies, in 2002 found no association between breast cancer and chlorinated chemicals including DDT.

And in 2011, an institute of the National Academies of Sciences reported “a possible link” between breast cancer and some common ingredients of vehicle exhaust, benzene and 1,3-butadiene. But the report said the jury is still out for most other widespread chemicals, such as pesticides, ingredients of cosmetics and bisphenol A (BPA).

4 Comments

1. 1. sault 04:40 PM 2/25/13

   It's crazy that we're basically running an uncontrolled experiment on all these pollutants and their interaction with our bodies. The people who profited from the use of these chemicals took those profits decades ago and the cumulative damages have been accruing to society as a whole ever since.
   
   Industry devises 100s of new chemicals every year and it is impossible to do long-term studies on their effects before they're put into widespread use. We should AT LEAST make sure that chemicals that would tend to get taken in by the body, like the BPA in steel can liners or the flame retardants in seat cushions, would get the targeted scrutiny required to make sure they are safe.
   
   We also need to ensure that these chemicals don't persist and spread to contaminate other areas. The "Superfund" has been depleted since 2003 and the remaining balance has come from general revenues in he USA, i.e., adding to the deficit because the polluting industries can't pay:
   
   http://en.wikipedia.org/wiki/Superfund#Implementation
   
   We should AT LEAST get it fully-funded again and get EVERY site on the road to decontamination ASAP.

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2. 2. johnson 06:50 PM 2/25/13

   There is a recent article in the Wall Street Journal titled: "No ill effect found in human BPA exposure" by Robert Lee Hotz. Says the exposure levels are thousands of times too low to affect the human body. and concludes: "The World Health Organization, the European Food Safety Authority, and Japan's National Institutes of Advanced Industrial Sciene and Technology have all dicounted its risk to human health."

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3. 3. ErnestPayne 03:24 PM 2/28/13

   I have a hunch that the widespread introduction of chemicals into our lives has lead to more than just increases in breast cancer. Unfortunately serious studies can take years to develop and produce results.

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4. 4. IslandGardener 05:15 AM 3/5/13

   Decades ago I read a novel by Doris Lessing in which she said something like this, that we'd given ourselves cancer by producing all sorts of new chemicals which had poisoned us. At first I thought 'how ridiculous' and then the more I thought about it the more it made sense. Rachel Carson's 'Silent Spring' had pointed out a similar thing for birds and other species.
   It's interesting that at last the evidence is mounting up - it may take years for cancers to show themselves, so it's tough for epidemiologists to work out the possible factors involved.

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