Skip to content

    Brain & Nervous System Health Center

    Font Size
    A
    A
    A

    How PCBs May Hurt the Brain

    New Studies Shed Light on Exposure to Environmental Toxin and Development of Brain Cells
    By
    WebMD Health News
    Reviewed by Louise Chang, MD

    April 13, 2009 -- Exposure to environmental toxins known as PCBs have long been linked with behavioral and developmental problems in children, but scientists could never say exactly how PCBs (polychlorinated biphenyls) might adversely affect the brain and lead to the problems.

    Now, scientists think they may know.

    The chemicals adversely affect the development of brain cells and also make brain circuits "overexcited," which has been linked in previous research to developmental problems, according to researcher Isaac N. Pessah, PhD, a professor of molecular biosciences and director of the University of California Davis Center for Children's Environmental Health.

    "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," says Pessah, a co-author on a trio of new studies examining the issue. The latest of the three is published online today in PLoS-Biology.

    The findings of the three studies are called a "turning point" by another expert in the field.

    One surprise finding: low levels of PCB exposure sometimes have greater ill effects than high-dose exposures.

    PCBs were widely used for years in many products such as electronic components, pesticides, caulking, and flame retardants, but their production was banned in the U.S. in 1979.

    Even so, the chemicals persist in the environment because they don't break down easily, explaining why high levels of PCBs can still be detected in people and in animals. PCBs are found in air, water, soil, and contaminated foods such as fish.

    PCB Exposure and Effect on Learning and Brain Cells

    In one of the three new studies, exposures to low doses of PCBs in animals hampered their ability to learn to swim a maze, a common test of animal learning.

    The low PCB doses also adversely affected the plasticity of the animals' dendrites -- small projections branching out from the neurons or nerve cells that get signals from other cells in the body.

    "This plasticity is very important for learning and memory," says study researcher Pamela Lein, PhD, associate professor of neurotoxicology at the UC Davis School of Veterinary Medicine.

    1 | 2 | 3

    Today on WebMD

    nerve damage
    Learn how this disease affects the nervous system.
    senior woman with lost expression
    Know the early warning signs.
     
    woman in art gallery
    Tips to stay smart, sharp, and focused.
    medical marijuana plant
    What is it used for?
     
    woman embracing dog
    Quiz
    boy hits soccer ball with head
    Slideshow
     
    red and white swirl
    Article
    marijuana plant
    ARTICLE
     
    brain illustration stroke
    Slideshow
    nerve damage
    Slideshow
     
    Alzheimers Overview
    Slideshow
    Graphic of number filled head and dna double helix
    Quiz