A new report in the journal Environmental Health Perspectives is calling for renewed attention to the growing evidence that many common and widely available chemicals endanger neurodevelopment in fetuses and children of all ages.
Chemicals that are of the most concern include lead and mercury; organophosphate pesticides used in agriculture and home gardens; phthalates, found 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 Dr. Susan Schantz, one of dozens of scientists who signed 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 U.S. in 1977, but can persist in the environment for decades, she said.
“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,” she continued. “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, such as phthalates and PBDEs, are known to interfere with normal hormone activity. For example, most pregnant women in the U.S. will test positive for exposure to phthalates and PBDEs, both of which disrupt thyroid hormone function, the scientist noted.
“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 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, which Schantz directs.
Phthalates also interfere with steroid hormone activity. Studies link exposure to certain phthalates with attention deficits, lower IQ and conduct disorders in children.
“Phthalates are everywhere — they’re in all kinds of different products,” she noted. “We’re exposed to them every day.”
The report criticizes 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.
“And if it looks like something is a risk, we feel policymakers should be willing to make a decision that this or that chemical could be a bad actor and we need to stop its production or limit its use,” she said. “We shouldn’t have to wait 10 or 15 years — countless children to be exposed to it in the meantime — until we’re positive it’s a bad actor.”
Source: University of Illinois at Urbana-Champaign
Photo: In addition to mercury and lead, flame retardants, air pollutants and chemicals found in many plastics, cosmetics and food containers endanger child brain health, researchers say. Credit: Julie McMahon.