Exposure to specific toxins in the environment, also known as PCBs (technically called polychlorinated biphenyls), appears to have an effect on the development of brain cells according to not one or two, but three new studies.
Toxic substances all around us have long been connected with problems in youngsters, but research couldn't explain exactly how PCB toxins impact the brain.
Once PCBs were used in a huge amount of goods, from pesticides, caulking, flame retardants and electronic components. The U.S. banned their use in the 1970s. However, these chemicals stick around in the environment because they do not easily break down.
They're still found in the air, are found seeping into our water supply, into the ground and often contaminating foods like fish that we eat. This is why PCBs are detectable in every one of us, even today.
The latest group of studies has found that these environmental toxins negatively affect the development of brain cells and overexcite brain circuits. This has been linked by earlier work to developmental problems.
"We think we have identified the way in which a broad class of environmental contaminants influences the developing nervous system and may contribute to neuro-developmental impairments such as hyperactivity, seizure disorders, and autism," explains researcher Isaac N. Pessah, PhD. The latest of the three studies appears in the April 2009 online issue of PLoS-Biology.
One surprise that came from the research is that lower levels of PCB exposures sometimes were more harmful than higher level exposures.
One of the studies uncovered that exposure to low doses of PCBs detrimentally effected animal subjects' ability to learn to navigate a maze, a common way to check learning ability in the lab.
Even low doses of PCBs adversely affected the plasticity of the dendrites, which are vitally important to learning and memory. Problems like this have been linked to conditions like autism, schizophrenia and even mental retardation.
The first study was published in the March 2009 issue of Environmental and Health Perspectives.
For the second of the studies, tissue from an animal's hippocampus (part of the brain that manages memory and emotion) was researched in order to analyze the excitability of neurons prior to and during exposures to two different PCBs.
The normal brain should have a balance between excitation and inhibition of the neurons, as too much excitability isn't useful. Conditions like autism and attention deficit hyperactivity disorder (ADHD) may involve an imbalance between the two states.
The second study is published in the March 2009 issue of Toxicology and Applied Pharmacology.
The third study looked at a cellular level, looking specifically at how PCBs might affect cell development (as they saw from the first study) and the level of excitement (what they found from that second study).
The researchers exposed receptors in the brain cells that control the release of calcium (key to keeping signalling normal from cell to cell) to PCBs. They found that PCBs bind to the receptors and hinders the release of calcium.
It's actually this that might account for the results in the other two studies.
"I think that these studies represent a kind of a turning point for our recognition of how these chemicals, PCBs, can interfere with brain development," says R. Thomas Zoeller, PhD, professor of biology at the University of Massachusetts, Amherst.
Now that there's a lab-backed explanation of how PCBs do their damage, this adds even more weight to the work researchers have done to link exposures to these environmental toxins and developmental problems.
It may also help us to arrive at a better way to evaluate the safety of chemicals that have replaced PCBs, and perhaps identify the dangerous ones before they become widely used.
What's more, the work shows us that even lower dose exposures to PCB toxins aren't always better and may not be safe at all.
Toxic substances all around us have long been connected with problems in youngsters, but research couldn't explain exactly how PCB toxins impact the brain.
Once PCBs were used in a huge amount of goods, from pesticides, caulking, flame retardants and electronic components. The U.S. banned their use in the 1970s. However, these chemicals stick around in the environment because they do not easily break down.
They're still found in the air, are found seeping into our water supply, into the ground and often contaminating foods like fish that we eat. This is why PCBs are detectable in every one of us, even today.
The latest group of studies has found that these environmental toxins negatively affect the development of brain cells and overexcite brain circuits. This has been linked by earlier work to developmental problems.
"We think we have identified the way in which a broad class of environmental contaminants influences the developing nervous system and may contribute to neuro-developmental impairments such as hyperactivity, seizure disorders, and autism," explains researcher Isaac N. Pessah, PhD. The latest of the three studies appears in the April 2009 online issue of PLoS-Biology.
One surprise that came from the research is that lower levels of PCB exposures sometimes were more harmful than higher level exposures.
One of the studies uncovered that exposure to low doses of PCBs detrimentally effected animal subjects' ability to learn to navigate a maze, a common way to check learning ability in the lab.
Even low doses of PCBs adversely affected the plasticity of the dendrites, which are vitally important to learning and memory. Problems like this have been linked to conditions like autism, schizophrenia and even mental retardation.
The first study was published in the March 2009 issue of Environmental and Health Perspectives.
For the second of the studies, tissue from an animal's hippocampus (part of the brain that manages memory and emotion) was researched in order to analyze the excitability of neurons prior to and during exposures to two different PCBs.
The normal brain should have a balance between excitation and inhibition of the neurons, as too much excitability isn't useful. Conditions like autism and attention deficit hyperactivity disorder (ADHD) may involve an imbalance between the two states.
The second study is published in the March 2009 issue of Toxicology and Applied Pharmacology.
The third study looked at a cellular level, looking specifically at how PCBs might affect cell development (as they saw from the first study) and the level of excitement (what they found from that second study).
The researchers exposed receptors in the brain cells that control the release of calcium (key to keeping signalling normal from cell to cell) to PCBs. They found that PCBs bind to the receptors and hinders the release of calcium.
It's actually this that might account for the results in the other two studies.
"I think that these studies represent a kind of a turning point for our recognition of how these chemicals, PCBs, can interfere with brain development," says R. Thomas Zoeller, PhD, professor of biology at the University of Massachusetts, Amherst.
Now that there's a lab-backed explanation of how PCBs do their damage, this adds even more weight to the work researchers have done to link exposures to these environmental toxins and developmental problems.
It may also help us to arrive at a better way to evaluate the safety of chemicals that have replaced PCBs, and perhaps identify the dangerous ones before they become widely used.
What's more, the work shows us that even lower dose exposures to PCB toxins aren't always better and may not be safe at all.
About the Author:
Next - Just head on over to the Daily Health Bulletin for more information on PCB toxins dangers, plus for a limited time get 5 free fantastic health reports. Click here for the video on how PCB toxins hurt the brain.
No comments:
Post a Comment