What Lead and Environmental Poisoning Does To Our Brains

It wasn’t until the 1960s that scientists found lead poisoning present in paint was being eaten by children and leading to brain damage. When lead is absorbed into the body it has devastating effects on the brain that damaged the wiring in significant and permanent ways.

The use of brain imaging in exploring the functions of the brain has also helped scientists see the effects environmental contaminants can have. The technology can even explorer the development of the brain inside the mother’s womb. How amazing is that? With it neuroscientists can offer at least a partial physical explanation as to why some children are born with developmental problems, lower intelligence, poor ability to function academically, and even as to why some have behavioral problems and inability to stay focused.

Scientists in both the United States and Canada have been documenting children in poorer neighborhoods, who are most prone to exposure to high levels of lead, air pollution and pesticides, for years. The studies are still in their early stages, but already there are worrisome questions cropping up between poverty and significant brain damage.

The problem they have encountered is that, although these contaminants may be present and contribute to poor performance and bad behavior in school, there are also other factors that need to be addresses “ such as poor nutrition, lack of early childhood stimulation, lower quality education, and other factors that are associated with poverty. Up until now most common problems in poor children were attributed to poor parenting or genetics.

For too long, we have blamed familial transmission of poverty to poor parenting or genetics. This emerging research helps confirm that reducing exposures to environmental pollutants, which are more common in poor children “ will reduce higher rates of learning problems and behavioral problems in poor children, said Simon Fraser University’s Bruce Lanphear, who is also affiliated with BC Children’s Hospital. Together with neuroscientist Kim Cecil from Cincinnati Children’s Hospital, they have studied new evidence about how lead, known to be a neurotoxin for more than a century, does permanent damages children’s brains.

“Being able to see a change in brain structure or function is compelling to people in a new way that traditional assessment tools are not,” said Harvard University’s David Bellinger, an expert on the impact of lead.

In the Cincinnati study, all of the volunteers grew up in impoverished inner-city homes. Some had more exposure to lead than others. Through the use of the specialized MRI scans, which were able to microscopically examine the size, shape and activity of their brains the scientists were able to find significant differences in the brains of adults who were exposed to higher levels of the heavy metal. “Some circuits don’t work right for others, the connections aren’t very efficient. It explains the lower IQ, the cognitive problems, some of the irritability and aggressive tendencies,”says Dr. Cecil.

Sophisticated MRI is also being used to study neurodevelopment effects of pesticides, air pollution, tobacco smoke and bisphenol A (BPA), a chemical found in some plastics.

High levels of toxic exposure are not limited to the poor, however. Recently, researchers in Quebec found that children who had high levels of manganese in their drinking water performed significantly worse on tests than children with lower levels of the metal in their drinking water. “There was no relation between income levels and exposure,” says University of Montreal’s Maryse Bouchard.

Colombia University researchers, like Bradley Peterson and Frederica Perera, have been working with expectant mothers from Washington Heights, Harlem and the South Bronx exposed to high levels of polycyclic aromatic hydrocarbons, or PAHS. The women carried backpacks with equipment that could measure PAHS, one component of air pollution. They also studied how the pesticide chlorpyrifos and secondhand smoke impacted brain development.

“We believe that different toxins have different effects on different regions and pathways,” he said, but there may be some overlap.

The children of these women are now in their mid 20s. The researchers are still tracking 250 of them (since before they were born). All of them were born with lead in their blood in various concentrations. According to Bellinger, there is no established safe level for lead exposure, but 10 micrograms per deciliter is considered high. The children’s ration was anywhere from 5-37 micrograms.

Each of the now-adults was tested four times a year until they were five, and twice a year until they were 6-1/2. The ones with the higher levels between ages three and six were found to have lower brain density as adults, especially in the frontal lobes of the young men.

Even more fascinating, the brains of those exposed to higher levels of lead have been trying to compensate for the damage done to them earlier. “These parts of the brain develop early, Dr. Cecil said, and it keeps trying to repair them.”

About the author:

Ron White is a two-time U.S.A. Memory Champion and memory training expert. As a memory keynote speaker he travels the world to speak before large groups or small company seminars, demonstrating his memory skills and teaching others how to improve their memory, and how important a good memory is in all phases of your life. His CDs and memory products are also available online at BrainAthlete.com.


Globe and Mail: Brain Imaging Measures Effects of Lead on Development: http://www.theglobeandmail.com/news/technology/science/brain-imaging-measures-effects-of-lead-on-development/article1736205/

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