Scientists are increasingly uncovering the ways in which ubiquitous industrial chemicals are damaging children's brain development, condemning a generation of children to neurobehavioral disorders from hyperactivity to autism.
According to the U.S. Centers for Disease Control and Prevention, there were 1.8 million more children diagnosed with developmental disabilities from 2006 to 2008 than there were a decade before. Over that same time period, there was a 33 percent increase in cases of attention deficit hyperactivity disorder (ADHD), and a shocking 300 percent increase in cases of autism. Between 10 to 15 percent of all U.S. children will eventually be diagnosed with some neurobehavioral disorder; the real prevalence is believed to be even higher.
The problem appears to be worldwide, and is so severe that prominent researchers Philippe Grandjean of the University of Southern Denmark and Harvard T.H. Chan School of Public Health and Philip Landrigan of the Icahn School of Medicine at Mount Sinai in New York have called it a "pandemic."
Increased diagnosis cannot fully explain the increase, say many researchers, including Irva Hertz-Piccioto of the University of California-Davis. The rates are actually increasing, and many scientists believe that environmental contaminants are largely to blame.
How household and industrial pollution damage the developing brain
Brain damage begins in the womb, when mothers are exposed to toxic chemicals - many of which pass through the placenta and straight to the fetus. Because the brain is still developing at this early stage, it is actually especially vulnerable to long-term disruption.
"The brain is so extremely sensitive to external stimulation," Grandjean said.
Many chemicals and metals have been long known to pose risks to children's brains, yet even these - such as lead, mercury, or organophosphate pesticides - are still widespread in the environment. Pesticide residues are found on foods or in the air and soil in agricultural areas; lead is still found in paint or even children's toys; and mercury is found in fish and in air pollution from coal-fired power plants.
But science is now uncovering entire new families of problematic chemicals in everything from plastics to furniture to indoor and outdoor air. Many of these are chemicals previously identified as endocrine (hormone) disruptors, which researchers are only now realizing can also damage the brain. This is because hormones such as thyroid or sex hormones play important roles in brain developments.
Endocrine disruptors believed to damage the brain include flame retardants (found in furniture, electronics and infant sleep products), PCBs, plastics chemicals such as BPA and phthalates, and perfluorinated compounds such as Teflon.
Recent research has also shown that many widespread air pollutants can also damage children's brains - such as polycyclic aromatic hydrocarbons, a byproduct of burning fossil fuels, which has been linked to ADHD.
Regulatory overhaul needed
Realizing how dangerous these toxic substances are, we naturally want to reduce our children's exposure to them. But it can be hard to identify which chemicals are dangerous, and many of those already identified are now so prevalent that it is nearly impossible to avoid them. In addition, many toxic substances are used in products where they do not need to be labeled or identified.
Grandjean and Landrigan place much of the blame for this situation on the U.S. regulatory system, which does not require manufacturers to prove chemicals safe before they are permitted for use.
"Untested chemicals should not be presumed to be safe to brain development, and chemicals in existing use and all new chemicals must therefore be tested for developmental neurotoxicity," they wrote in an article in the prestigious journal The Lancet.
"To me it is very clear we have to set up a different system to better protect the brains of the future," Grandjean said.