Until recently, scientists thought that human fetuses growing inside mothers' wombs were shielded from environmental toxins. But the author of a new book called "Having Faith" says these pollutants can contaminate the fetus through the mother.
When biologist Sandra Steingraber had her first pregnancy assessment ultrasound she saw the baby she named Faith 'swimming' in her uterus. From that moment on she felt that she had become a habitat for her child. And she started researching how safe a habitat she was. She says the results were alarming. Her research - which led to her book "Having Faith" - found that the womb was an ecosystem fraught with environmental pollutants. "The placenta is really an open doorway," she explains." Whatever contaminants exist in the outside environment, in which we all - as human adults - inhabit, will also find their way into the interior environment of a pregnant woman's body. Whatever residues are in the food that adult pregnant women eat, these chemicals will also find their way into the uterus."
These toxins are called Persistent Organic Pollutants, or POPs. They are organic chemicals that enter the food chain from contaminated water and soil. Dr. Steingraber says they accumulate in the bodies of animals and people faster than they are excreted. And Dr. Steingraber says a pregnant woman is likely to pass those POPs on to her fetus.
Dr. Steingraber says that the most notorious members of the Persistent Organic Pollutant group are insecticides such as DDT, industrial oils called PCBs (polychlorinated biphenyls), and industrial by-products such as Methylmercury - a toxic compound of mercury.
These toxins, she says, are carcinogenic, and recent research has shown that they can cause neurological and brain deficiencies in fetuses. Dr. Steingraber says that some types of these pollutants are found in industrial countries, while others contaminate poor, agrarian societies. For example DDT is still used in Africa, where malaria is a serious problem, to kill the mosquitoes that transmit the disease.
And DDT, explains Dr. Steingraber, can find its way to the fetus.
"One of the things that I was surprised to discover when I did the research for 'Having Faith' is that the amniotic fluid itself can be tainted with DDT, the old pesticide," she says. " Amniotic fluid is that kind of liquid that surrounds the baby that is actually swimming in. Of course the baby swallows this fluid and it is absorbed across the skin."
Although DDT is banned in the industrial world, toxins such as PCBs still are used in some western countries for the production and transmission of electricity. And Dr. Steingraber says that even though PCBs have been banned in the United States since 1977, they are so persistent that they still linger in the environment.
Dr. Steingraber says coal burning power plants also produce another serious toxin, methyl mercury. She says mercury emissions from American power plants now approach 100,000 pounds each year. Dr. Steingraber points out that clinical studies consistently find higher levels of methyl mercury in the blood of newborns than in blood samples drawn from their mothers.
"A lot of these toxins that I am concerned about that harm children actually accumulate as they move up the food chain. They concentrate. This is called biomagnification," she explains.
And, Dr. Steingraber says, this biomagnefication also affects breast milk. So, environmental toxins continue to pass from the mother to the nursing baby. "They tend to be soluble in fat instead of water. And breast milk like cow's milk is 4% butter fat. It is very fatty, and also they concentrate as they move up to food chain. It is like a sauce on the stove," she says. " The flavor is concentrated the more you simmer it. So, by the time the food gets all the way up to nursing infants it has had a chance to concentrate sometimes a million-fold higher that what you would find let's say just out in the lake water or the ocean or the air or the soil." Dr. Steingraber suggests that pregnant women and new mothers who want to protect themselves from absorbing additional contaminants should cut down on eating fish. She says recent research shows that fish - more than other animals or plants - carry mercury and PCBs released into water. But she stresses that cutting down on nutritious food should not be a permanent solution.
"Certainly we are very free to tell pregnant women 'don't drink' or ' don't smoke', or 'cut down on junk food or stay away from raw fish and sushi and alcohol'. There seems to be a double standard because industry and agriculture are very free to disseminate toxins into the environment," says the doctor.
Dr. Steingraber says agricultural toxins include runoff that dumps pesticides into nearby waterways. She says that divorcing agriculture from such pesticides, as well as developing clean energy sources that do not spread PCBs and mercury, are critical to preventing toxic contamination of fetuses and infants.