(CNN) — The number of chemicals known to be toxic to children’s
developing brains has doubled over the last seven years, researchers said.
Dr. Philip Landrigan at Mount Sinai School of Medicine in New York and Dr. Philippe
Grandjean from Harvard School of Public Health in Boston, authors of the review published
Friday in The Lancet Neurology journal, say the news is so troubling they are calling for
a worldwide overhaul of the regulatory process in order to protect children’s brains.
“We know from clinical information on poisoned adult patients that these chemicals
can enter the brain through the blood brain barrier and cause neurological
symptoms,” said Grandjean.
“When this happens in children or during pregnancy, those chemicals are extremely
toxic, because we now know that the developing brain is a uniquely vulnerable organ. Also,
the effects are permanent.”
The two have been studying industrial chemicals for about 30 years. In 2006, they
published data identifying five chemicals as neurotoxicants — substances that impact
brain development and can cause a number of neurodevelopmental disabilities including
attention-deficit hyperactivity disorder, autism, dyslexia and other cognitive damage,
they said.
Those five are lead, methylmercury, arsenic, polychlorinated biphenyls, or PCBs, and
toluene.
Banned in the United States in 1979, PCBs were used in hundreds of products including
paint, plastic, rubber products and dyes. Toluene is in household products like paint
thinners, detergents, nail polish, spot removers and antifreeze.
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chemicals in your food
Now, after further review, six more chemicals have been added to the list: manganese;
fluoride; tetrachloroethylene, a solvent; a class of chemicals called polybrominated
diphenyl ethers, or flame retardants; and two pesticides, chlorpyrifos, which is widely
used in agriculture, and dichlorodiphenyltrichloroethane, or DDT.
“The continuing research has identified six new chemicals that are toxic to the
developing human brain,” said Landrigan. “We’re turning up chemicals at the
rate of about one a year that we’re discovering are capable of damaging the developing
brain of a human fetus or human infant.”
To examine fluoride, which is in tap water in many areas, Landrigan and Grandjean looked
at an analysis of 27 studies of children, mostly in China, who were exposed to fluoride in
drinking water at high concentrations. The data, they said, suggests a decline on average
of about seven IQ points.
There’s another big concern: “We are very worried that there are a number of other
chemicals out there in consumer products that we all contact every day that have the
potential to damage the developing brain, but have never been safety tested,”
Landrigan said.
“Over the last six or seven years we are actually adding brain toxic chemicals at a
greater speed than we are adding toxicity evidence in children’s brains,” Grandjean
said.
“At least 1,000 chemicals using lab animals have shown that they somehow interfere
with brain function in rodents — rats and mice — and those are prime
candidates for regulatory control to protect human developing brains. But this testing has
not been done systematically.”
At greatest risk? Pregnant women and small children, according to Grandjean. According to
the review, the biggest window of vulnerability occurs in utero, during infancy and early
childhood.
The impact is not limited to loss of IQ points.
“Beyond IQ, we’re talking about behavior problems — shortening of attention
span, increased risk of ADHD,” Landrigan said.
“We’re talking about emotion problems, less impulse control, (being) more likely to
make bad decisions, get into trouble, be dyslexic and drop out of school. … These
are problems that are established early, but travel through childhood, adolescence, even
into adult life.”
BPA,
phthalate exposure may cause fertility problems
It’s not just children: All these compounds are toxic to adults, too. In fact, in 2006 the
pair documented 201 chemicals toxic to the adult nervous system, usually stemming from
occupational exposures, poisonings and suicide attempts.
The American Chemistry Council, meanwhile, called the review a “rehash” of the
authors’ first review.
“This iteration is as highly flawed as the first, as once again the authors ignore
the fundamental scientific principles of exposure and potency,” said council
spokesman Scott Jensen.
“What is most concerning is that the authors focus largely on chemicals and heavy
metals that are well understood to be inappropriate for children’s exposure, are highly
regulated and/or are restricted or being phased out. They then extrapolate that similar
conclusions should be applied to chemicals that are more widely used in consumer products
without evidence to support their claims. Such assertions do nothing to advance true
scientific understanding and only create confusion and alarm.”
Landrigan and Grandjean now say all untested chemicals in use and all new chemicals should
be tested for developmental neurotoxicity.
This is not a new concept. In 2007, the European Union adopted regulations known as REACH
— Registration, Evaluation, Authorisation and Restriction of Chemicals — to
protect human health from risks posed by chemicals. REACH covers all chemicals, placing
the burden of proof on companies to prove that any chemicals they make are safe.
“We are behind right now and we’re falling further behind,” Landrigan said.
“… I find it very irritating some of the
multinational manufacturers are now marketing products in Europe and the U.S. with the
same brand name and same label, but in Europe (they) are free of toxic chemicals and in
the U.S. they contain toxic chemicals.”
The best example of this, he said, is cosmetics and phthalates. Phthalates are a group of
chemicals used in hundreds of products from cosmetics, perfume, hair spray, soap and
shampoos to plastic and vinyl toys, shower curtains, miniblinds, food containers and
plastic wrap.
You can also find them in plastic plumbing pipes, medical tubing and fluid bags, vinyl
flooring and other building materials. They are used to soften and increase the
flexibility of plastic and vinyl.
In Europe, cosmetics don’t contain phthalates, but here in the United States some do.
Phthalates previously were used in pacifiers, soft rattles and teethers.
But in 1999, after a push from the U.S. Consumer Product Safety Commission, American
companies stopped using them in those products.
“We certainly have the capability, it’s a matter of political will,” Landrigan
said. “We have tried in this country over the last decade to pass chemical safety
legislation but the chemical industry and their supporters have successfully beat back the
effort.”
However, the Food and Drug Administration said two of the most common phthalates, —
dibutylphthalate, or DBP, used as a plasticizer in products such as nail polishes to
reduce cracking by making them less brittle, and dimethylphthalate, or DMP used in
hairsprays — are now rarely used in this country.
Diethylphthalate, or DEP, used in fragrances, is the only phthalate still used in
cosmetics, the FDA said.
“It’s not clear what effect, if any, phthalates have on human health,”
according to the FDA’s website. “An expert panel convened from 1998 to 2000 by the
National Toxicology Program (NTP), part of the National Institute for Environmental Safety
and Health, concluded that reproductive risks from exposure to phthalates were minimal to
negligible in most cases.”
But Grandjean is unfazed.
“We know enough about this to say we need to put a special emphasis on protecting
developing brains. We are not just talking about single chemicals anymore. We are talking
about chemicals in general.”
“This does not necessarily mean restrict the use of all chemicals, but it means that
they need to be tested whether they are toxic to brain cells or not,” he said.
“We have the test methods and protocols to determine if chemicals are toxic to brain
cells. If we look at this globally, we are looking at more than a generation of children
— a very high proportion of today’s children have been exposed to lead, mercury and
other substances, including substances that have not yet been tested but are suspect of
being toxic to brain development.”
The Environmental Working Group is an environmental health research organization that
specializes in toxic chemical analysis and has long called for reforms. In 2004, the group
tested 10 samples of umbilical cord blood for hundreds of industrial pollutants and found
an average of 200 in each sample.
“Here in the U.S., the federal law put in place to ostensibly protect adults and
children from exposures to dangerous chemicals, including those that can present serious
risks to the brain and nervous systems, has been an abject failure,” said
Environmental Working Group spokesman Alex Formuzis.
“The 1976 Toxic Substances Control Act has instead been largely responsible for the
pollution in people beginning in the womb, where hundreds of industrial contaminants
literally bathe the developing fetus.”
Landrigan is recruiting pregnant women for a new study that will test for chemical
exposures. He said it’s inevitable that over the next few years more chemicals will be
added to the list.
His concern? “The ability to detect these chemicals lags behind the chemical
industries’ ability to develop new chemicals and put them into consumer products. That’s
why we need new legislation in this country to close that gap.”
“We are lagging behind,” Grandjean said. “And we are putting the next
generation of brains in danger.”