A Host of Common Chemicals Endanger Child Brain Development, Report Says

Summary: A new report calls for renewed attention to the growing evidence that many common and widely available chemicals endanger neurodevelopment in fetuses and children of all ages.

Source: University of Illinois.

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, 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 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 U.S. 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.

“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.”

Schantz is a faculty member in the College of Veterinary Medicine and in the Beckman Institute for Advanced Science and Technology at the U. of I.

“The human brain develops over a very long period of time, starting in gestation and continuing during childhood and even into early adulthood,” Schantz said. “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 U.S. will test positive for exposure to phthalates and PBDEs, both of which disrupt thyroid hormone function.

Image shows an infographic.

“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, 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. We’re exposed to them every day,” Schantz said.

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.

“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 — allowing countless children to be exposed to it in the meantime — until we’re positive it’s a bad actor.”

ABOUT THIS NEURODEVELOPMENT RESEARCH ARTICLE

Funding: The National Institute of Environmental Health Sciences at the National Institutes of Health and the U.S. Environmental Protection Agency fund the Children’s Environmental Health Research Center at the University of Illinois.

Source: Diana Yates – University of Illinois
Image Source: This NeuroscienceNews.com image is credited to Julie McMahon.
Video Source: The video is credited to Beckman Institute.
Original Research: Full open access research for “Project TENDR: Targeting Environmental Neuro-Developmental Risks. The TENDR Consensus Statement” by Bennett D, Bellinger DC, Birnbaum LS, Bradman A, Chen A, Cory-Slechta DA, Engel SM, Fallin MD, Halladay A, Hauser R, Hertz-Picciotto I, Kwiatkowski CF, Lanphear BP, Marquez E, Marty M, McPartland J, Newschaffer CJ, Payne-Sturges D, Patisaul HB, Perera FP, Ritz B, Sass J, Schantz SL, Webster TF, Whyatt RM, Woodruff TJ, Zoeller RT, Anderko L, Campbell C, Conry JA, DeNicola N, Gould RM, Hirtz D, Huffling K, Landrigan PJ, Lavin A, Miller M, Mitchell MA, Rubin L, Schettler T, Tran HL, Acosta A, Brody C, Miller E, Miller P, Swanson M, and Witherspoon NO. in Environmental Health Perspectives. Published online July 2016 doi:10.1289/EHP358

Endocrine Disrupting Chemicals Alter Thyroid Levels in Pregnancy and May Affect Fetal Brain Development

A new study led by biologist R. Thomas Zoeller of the University of Massachusetts Amherst provides “the strongest evidence to date” that endocrine disrupting chemicals such as polychlorinated biphenyls (PCBs) found in flame retardant cloth, paint, adhesives and electrical transformers, can interfere with thyroid hormone action in pregnant women and may travel across the placenta to affect the fetus.

Results appeared in an early online edition and in the December print edition of the Endocrine Society’s Journal of Clinical Endocrinology & Metabolism. The paper was honored this week as an “extramural paper of the month” by the National Institute of Environmental Health Sciences.

Zoeller says, “As endocrine-disrupting chemicals, PCBs interfere with the way the thyroid hormone functions, but they don’t actually change the amount of the hormone found in the body. Although these effects are largely invisible in scientific studies that only judge thyroid activity by measuring hormone levels, they may be having a real impact on infants’ brain development.”

Although endocrine-disrupting PCBs were banned in the United States in 1979, they are still released into the environment from disposal sites or products manufactured before the ban. Most people have been exposed to low levels of PCBs, Zoeller points out.

In this prospective birth cohort study, he and colleagues looked at the effects of low-dose chemical exposure in 164 pregnant women. Tissue from their placentas, the uterine structure that provides oxygen and nutrients to the fetus, was analyzed for a specific enzyme, CYP1A1, which changes endocrine-disrupting chemicals into a form that can interfere directly with the body’s thyroid hormone receptors.

This work was a collaboration between scientists in the biology department at UMass Amherst and physician scientists led by Larissa Takser at the University of Sherbrooke, Québec, who collected placental tissue from a large epidemiological study. Biochemistry and experimental work conducted at Zoeller’s UMass Amherst laboratory over the past decade provided the framework for the analyses. “This led us to predict specific molecular events that might be occurring in the placenta,” he notes, “and as best as we can tell right now, we were correct.”

The image shows a pregnant woman. A ultrasound scan of a baby is layered on to her stomach.

Zoeller and colleagues found that in pregnancies where the placenta contained higher levels of CYP1A1, it also showed signs of thyroid disruption. Levels of two thyroid-regulated genes tended to be higher in these pregnancies, although the mother’s overall thyroid hormone levels did not change.

“Whatever is happening in the placenta likely reflects what is happening in the fetus,” says Zoeller. “To truly understand how endocrine-disrupting chemicals may be affecting pregnancies, the findings show we need to study not only hormone levels, but hormone activity at the cellular level.”

The effects of endocrine-disrupting chemicals may be particularly insidious in people who smoke, Zoeller said. The enzyme CYP1A1 is supposed to clean the blood, and the body produces more of this enzyme when it is exposed to cigarette smoke. The researchers found pregnant women who smoked tended to have higher levels of the enzyme in the placental tissue.

ABOUT THIS NEURODEVELOPMENT RESEARCH

In addition to Zoeller, other authors at UMass Amherst are Thomas Luke Wadzinski, Katherine Geromini, Judy McKinley Brewer and Ruby Bansal, with Nadia Abdelouahab and Marie-France Langlois in addition to Takser at the University of Sherbrooke.

Contact: Janet Lathrop – University of Massachusetts Amherst
Source: University of Massachusetts Amherst press release
Image Source: The image is credited to Skitterphoto and is in the public domain
Original Research: Abstract for “Endocrine Disruption in Human Placenta: Expression of the Dioxin-Inducible Enzyme, Cyp1a1, Is Correlated With That of Thyroid Hormone-Regulated Genes” by Thomas L. Wadzinski, Katherine Geromini, Judy McKinley Brewer, Ruby Bansal, Nadia Abdelouahab, Marie-France Langlois, Larissa Takser and R. Thomas Zoeller in Journal of Clinical Endocrinology & Metabolism. Published online October 9 2014 doi:10.1210/jc.2014-2629