Studies Uncover PCB Toxins Dangers Exposure to PCBs (technically called polychlorinated biphenyls), may effect the development of brain cells according to three separate studies.
These toxic substances in the environment have http://www.enunblog.com/pcbonline/ long been linked with problems in children, but research could not explain how PCB toxins affect 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 in the air, seep into our water, are in the ground and contaminate the food we eat, like fish. PCBs are still detectable in all of us, even today.
The latest studies have found that these toxins affect the development of brain cells and overexcite brain circuits. This has been linked by earlier work to problems with development.
"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," said researcher Isaac N. Pessah, PhD. The latest of the 3 studies appears in the April 2009 online issue of PLoS-Biology.
One interesting finding that came from the study is that lower levels of PCB exposures were sometimes 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.
The second study took tissue from an animal's hippocampus (part of the brain that manages memory and emotion) and it was examined in order to check the excitability of neurons before and during exposures to two 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 report on the second study appears in the March 2009 issue of Toxicology and Applied Pharmacology.
The third study took things to the cellular level, looking at specifically how PCBs might change the cell development (as they saw from the first study) and the level of excitement (what they found from that second study).
This time, the researchers exposed receptors in the brain cells that regulate the release of calcium (key to keeping signalling normal from cell to cell) to PCBs. Analyzing with an electron microscopes, they found that PCBs cling to the receptors and affect the release of calcium.
It's this that could be the reason for the results found 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 http://pcbonline.pornlivenews.com/ and developmental problems.
It may also allow us come up with new ways to evaluate the safety of chemicals that have taken the place of PCBs, and maybe remove the dangerous ones before they become widely used.
The work shows us that even low dose exposures to PCB toxins aren't always safe.