Not long ago, scientists thought that the placenta protected babies in the womb from most pollutants in the environment. But a groundbreaking study has shown that in this critical period, the umbilical cord carries more than the building blocks of life. It also carries a steady stream of industrial chemicals, pollutants and pesticides. These pollutants cross the placenta as readily as residues from cigarettes and alcohol. The pollution in people that affects everyone in the world also affects babies in the womb.

Umbilical cord blood from 10 babies was tested for 413 industrial chemicals and pollutants. The tests found an average of 200 of these chemicals in each newborn, and a total of 287 chemicals in the group. The umbilical cord blood of the 10 babies harboured pesticides, consumer product ingredients, and wastes from burning coal, gasoline and garbage. Some of the chemicals found in the cord blood are banned or severely restricted in the US.

There is extensive scientific evidence that chemical exposures in the womb or during infancy can be dramatically more harmful than exposures later in life. Many of the chemicals which were found in the babies in this study are particularly hazardous, including mercury, PCBs and dioxins.

Scientists use the concept of “windows of vulnerability” to describe periods in which even minute exposures can result in permanent damage. A recent review by government scientists reveals that many of these windows of vulnerability are found in the early months of human pregnancies, when cells are multiplying and differentiating into specific tissues and organs. An exposure that could harm a developing fetus may have no effect at all on the mother.

Some effects may be immediately noticeable when a child is born, such as severe birth defects. Others may be subtle but important changes that surface later in childhood as learning or behaviour problems, or in adulthood as cancer or neurodegenerative disease.

The study was carried out by two non-profit organizations in the US, the Environmental Working Group and Commonweal. “Had we tested for a broader array of chemicals, we would almost certainly have detected more than 287,” wrote the study’s authors. “... US industries manufacture and import approximately 75,000 chemicals, 3,000 of them at over a million pounds a year. Health officials do not know how many of these chemicals pollute fetal blood and what the health consequences of in utero exposures may be. No one has ever studied the dangers of exposure to this complex mixture of chemicals either before or after birth.”

The study underlines the urgent need for public health policies and regulations that take into account fetal and childhood sensitivities. Safety levels have traditionally been established using healthy adult males as the norm. After nearly a decade of study, the US Environmental Protection Agency recently updated its cancer risk guidelines, explicitly recognizing the importance of childhood exposures. The EPA concluded that cancer causing chemicals are, on average, 10 time more potent for babies than adults, and that some chemicals are up to 65 times more powerful.

But there is still a gaping hole in regulation of chemicals which damage the immune system, the brain, hormones, thyroid and a host of other potential targets, taking into account the vulnerability of children and babies in the womb.

The full study, Body Burden: The Pollution in Newborns , is available at www.ewg.org/reports/bodyburden2/).