New
Urgency in the Need for PCB Removal
Based on Important New Biological
Information Regarding how these
compounds impact on the human brain and
behavior
Recently published
data have worked out the mechanisms by
which PCBs found in the environment may
affect the developing brain and nervous
system. For the first time, there is now
a plausible biological mechanism to
explain the effects of PCBs on behavior.
PCB compounds leaked
into the environment may result in
behavioral and developmental problems in
children. Newly worked out biological
mechanisms of neural damage speak
strongly for the removal of all PCB
contamination from the environment as
quickly as possible.
Three newly
published studies highlight the studied
mechanisms of action of PCB compounds on
brain tissues.
In one study,
published by D. Yang in the March, 2009
edition of Environmental and Health
Perspectives PCB exposure adversely
affected the experience dependent
plasticity of neural dendrites – small
projections branching out from the
neurons or nerve cells which receive
signals from other cells in the body.
Neural plasticity is essential for
learning and memory, and restriction in
dendritic plasticity is implicated in
autism, schizophrenia and mental
retardation.
A 2nd article
published by K. Kim in the March, 2009
edition of Toxicology and Applied
Pharmacology found that in animal
studies the hippocampus, a region of the
brain responsible for regulating memory
and emotion was firing too rapidly, a
condition known as enhanced excitation.
Neurodevelopmental conditions such as
autism and attention deficit
hyperactivity disorder (ADHD) are
causally linked to alterations in the
level of excitability of the hippocampal
neuronal activity.
A third study
published by M Samso et al in PLoS
Biology in April, 2009 evaluated the
effects of PCBs at the cellular level.
In laboratory studies this research team
evaluated the means by which neural
cells release the intercellular
messenger molecule calcium. Using
electron microscopy, they determined
that PCBs bind to ryanodine receptors,
an intracellular calcium channel and
interfere with calcium release. In so
doing PCBs keep the ryanodine receptors
in an open position, therefore
interfering with the cellular activity
of brain cells. Keeping the receptors
open can explain why PCBs result in
overexcitation of neural circuits.
Taking all of these
three studies into perspective it is now
clear from the cellular level to the
organ level that PCBs are an imminent
danger to animal and human life and that
their cleanup is essential in as timely
a means as feasible.
