The number of industrial chemicals with known links to neurodevelopmental disabilities like autism has more than doubled in the past seven years, according to new research published in The Lancet
rates of autism and attention deficit-hyperactivity disorder (ADHD)
increase worldwide, researchers believe widespread exposure to these
chemicals among children may be contributing to a “silent epidemic” of
people with neurodevelopmental disabilities.
Based on an analysis
of previous studies, researchers added six new toxins to a list of
chemicals believed to pose a threat to the brains of fetuses and young
children: manganese, fluoride, chlorpyrifos,
dichlorodiphenyl-trichloroethane (DDT), tetrachloroethylene, and the
polybrominated diphenyl ethers.
While chemicals like manganese
and fluoride, common in drinking water, are rarely found in high enough
concentrations in the U.S. to pose a health threat, other chemicals on
the list are much more pervasive.
“Chlorpyrifos is an organic
pesticide … 10 years ago it was banned for household use, but it is
still extensively used in agriculture and can be found in lots of fruits
and vegetables,” study co-author Dr. Philip Landrigan, of the Icahn
School of Medicine at Mount Sinai in New York City, told FoxNews.com.
the list gets scarier: Tetrachloroethylene, which has been linked to
deficient neurological function and increased risk of psychiatric
diagnosis, is a common solvent used in dry cleaning.
Another chemical on
the list, polybrominated diphenyl ethers, is a type of flame retardant
frequently found in couches. And while the pesticide DDT is now banned
in the U.S. due to human health risks, it’s still found in imported
fruits and vegetables, as well as in soil and water throughout the
These six chemicals have been added to a list of five
other neurointoxicants – lead, methylmercury, polychlorinated biphenyls,
arsenic, and toluene – first identified by Landrigan and his co-author,
Dr. Phillipe Grandjean of the Harvard School of Public Health, in 2006.
How chemicals harm the developing brain
Industrial chemicals pose a far greater threat to the neurological
health of a developing fetuses, infants and young children than to
adults, Landrigan noted.
During the early weeks of pregnancy, an
embryo forms the cells that eventually go on to become the brain and
spinal cord. Those cells divide, multiply and migrate, forming millions
or even billions of connections with surrounding cells – and build up
the pathways that form the body’s central nervous system.
some chemical gets in to the developing brain, whether lead or
methylmercury, and either kills brain cells or disrupts cell division or
cell migration, those connections are lost and the brain is not as
complete as it should have been,” Landrigan said. “And the consequence
is a child whose intelligence is reduced and attention span shortened,
etc. The human brain is a wondrous creation, and extremely complex, but
the price of that complexity is vulnerability.”
researchers acknowledge that increasing rates of conditions like ADHD
and autism are partially due to increased awareness about these
conditions, they argue that other factors are also at play.
note the increase of later diagnoses of these disorders tracks very
nicely with increased production and release into environment of
synthetic chemicals over last 40 or 50 years,” Landrigan said. “And then
on top of that, there’s the direct evidence we present in [the] paper
showing these particular chemicals have been linked to these problems in
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