In a new report, dozens of scientists, health practitioners, and children’s health advocates are calling for renewed attention to the growing evidence that many common and widely available chemicals endanger neurodevelopment in fetuses and children of all ages.
The chemicals that are of most concern include lead and mercury; organophosphate pesticides used in agriculture and home gardens; phthalates, which are used in pharmaceuticals, plastics and personal care products; flame retardants known as polybrominated diphenyl ethers; and air pollutants produced by the combustion of wood and fossil fuels, said University of Illinois comparative biosciences professor Susan Schantz, one of dozens of individual signatories to the consensus statement.
Polychlorinated biphenyls, once used as coolants and lubricants in transformers and other electrical equipment, also are of concern. PCBs were banned in the US in 1977, but can persist in the environment for decades, she said.
The new report, “Project TENDR: Targeting Environmental NeuroDevelopment Risks,” appears in the journal Environmental Health Perspectives. The group also has a website with information about each of the chemicals of concern.
90 percent of pregnant women in the US have detectable levels of 62 chemicals in the bodies out of the 163 screened in this study. In addition to mercury and lead, flame retardants, air pollutants and chemicals found in many plastics, cosmetics and food containers can disrupt child brain development, researchers say.
“These chemicals are pervasive, not only in air and water, but in everyday consumer products that we use on our bodies and in our homes,” Schantz said. “Reducing exposures to toxic chemicals can be done, and is urgently needed to protect today’s and tomorrow’s children. … The human brain develops over a very long period of time, starting in gestation and continuing during childhood and even into early adulthood, but the biggest amount of growth occurs during prenatal development. The neurons are forming and migrating and maturing and differentiating. And if you disrupt this process, you’re likely to have permanent effects.”
Some of the chemicals of concern, such as phthalates and PBDEs, are known to interfere with normal hormone activity. For example, most pregnant women in the US will test positive for exposure to phthalates and PBDEs, both of which disrupt thyroid hormone function.
“Thyroid hormone is involved in almost every aspect of brain development, from formation of the neurons to cell division, to the proper migration of cells and myelination of the axons after the cells are differentiated,” said Schantz. “It regulates many of the genes involved in nervous system development.”
Schantz and her colleagues at Illinois are studying infants and their mothers to determine whether prenatal exposure to phthalates and other endocrine disruptors leads to changes in the brain or behavior. This research, along with parallel studies in older children and animals, is a primary focus of the Children’s Environmental Health Research Center at Illinois.
Phthalates, which are ubiquitous in our daily lives, also interfere with steroid hormone activity. Studies link exposure to certain phthalates with attention deficits, lower IQ and conduct disorders in children.
The report criticizes current regulatory lapses that allow chemicals to be introduced into people’s lives with little or no review of their effects on fetal and child health.
“For most chemicals, we have no idea what they’re doing to children’s neurodevelopment,” Schantz said. “They just haven’t been studied.”