Daily Telegraph (UK)  [Printer-friendly version]
November 9, 2006


[Rachel's introduction: Scientists from Holland and the U.S. have
identified 202 industrial chemicals with the potential to damage the
human brain and these are likely to be the "tip of a very large
iceberg," they say]

By John von Radowitz

Millions of children worldwide may have suffered brain damage as a
direct result of industrial pollution, scientists say.

An explosive report talks of a "silent pandemic" of
neurodevelopmental disorders caused by toxic chemicals spilling into
the environment.

They include conditions such as autism, attention deficit disorder,
mental retardation and cerebral palsy. All are common and can result
in lifelong disability, but their causes are largely unknown.

The scientists, from Holland and the US, identified 202 industrial
chemicals with the potential to damage the human brain, and said they
were likely to be the "tip of a very large iceberg". More than 1,000
chemicals are known to be neurotoxic in animals, and are also likely
to be harmful to humans.

The researchers made an urgent call for much tighter worldwide
controls on chemicals, and a "precautionary approach" to testing. Dr
Philippe Grandjean, from the Department of Environmental Medicine at
the University of Southern Denmark in Winslowparken, one of the
study's two authors, said: "The human brain is a precious and
vulnerable organ.

"And because optimal brain function depends on the integrity of the
organ, even limited damage may have serious consequences. Even if
substantial documentation on their toxicity is available, most
chemicals are not regulated to protect the developing brain. Only a
few substances, such as lead and mercury, are controlled with the
purpose of protecting children.

"The 200 other chemicals that are known to be toxic to the human brain
are not regulated to prevent adverse effects on the foetus or a small
child." Grandjean and co-author Professor Philip Landrigan, from the
Mount Sinai School of Medicine in New York, trawled a range of
scientific data sources to compile their evidence.

Five substances for which sufficient toxicity evidence exist were
examined in detail -- lead, methylmercury, arsenic, polychlorinated
biphenyls (PCBs) and toluene. In each case, the dangers came to light
the same way.

First, there was a recognition of high dosage toxicity in adults, and
records of isolated episodes of poisoning among children. This was
followed by a growing body of epidemiological evidence that lower
levels of exposure in children led to neurobehavioral defects.

Pinning down the effects of industrial chemical pollution is extremely
difficult because they may not produce symptoms for several years or
even decades, said the scientists. This was why the pandemic is
"silent". The damage caused by individual toxic chemicals is not
obviously apparent in available health statistics.

But the extent of the sub-clinical risk to large populations is
illustrated by the legacy of lead. Virtually all children born in
industrialised countries between 1960 and 1980 must have been exposed
to lead from petrol, said the researchers. Based on what is known
about the toxic effects of lead, this may have reduced exceptional IQ
scores of above 130 by more than half, and increased the number of
scores less than 70.

Other results of lead exposure included shortened attention span,
slowed motor coordination and heightened aggressiveness. In later
life, early damage from lead can increase the risk of Parkinson's and
other neurodegenerative diseases.

Today, it is estimated that lead poisoning in children costs the US
economy $A55 billion each year. One in six children is thought to have
some kind of developmental disability, usually involving the nervous

Developing brains are much more susceptible to toxic chemicals than
those of adults, pointed out the scientists. Interference with complex
changes taking place in the developing brain can have permanent
consequences. And research had shown that this vulnerable period lasts
from the foetal stage of life through infancy and childhood to

Writing in the online version of The Lancet medical journal, the
scientists conclude: "The combined evidence suggests that
neurodevelopmental disorders caused by industrial chemicals has
created a silent pandemic in modern society.

"Although these chemicals might have caused impaired brain development
to millions of children worldwide, the profound effects of such a
pandemic are not apparent from available health statistics.
Additionally... only a few chemical causes have been recognised, so
the full effects of our industrial activities could be substantially
greater than recognised at present."

In the EU, 100,000 chemicals were registered for commercial use in
1981, and in the US, 80,000 are registered. Yet fewer than half had
been subjected to even token laboratory testing, said the report, and
in 80 per cent of cases there was no information about potential
danger to children.

Although new chemicals went through more rigorous testing, access to
the data could be restricted for commercial reasons. In the EU, a new
testing program called Reach is planned under proposed legislation
that will enforce tighter controls.

But the scientists said that even this does not go far enough, since
it fails to emphasise the importance of testing chemicals for
developmental neurotoxicity. "Toxicity testing protocols for chemicals
need to be expanded to include examination of neurobehavioral
functions," they said.

There was a mixed reaction to the research from other experts.

Professor Mark Hanson, director of developmental origins of health and
disease at Southampton University, said: "The authors have put their
finger on something which is important and which will not go away. The
review, in a way, is timely because it will stir up debate and
hopefully generate more research in this area. There is no need to
panic, but we can't ignore this possible problem."

Professor Alan Boobis, from the section of experimental medicine and
toxicology at Imperial College London, said: "The authors of this
review have raised an issue of significant concern, but some of the
evidence in support of the conclusions lacks rigour. This is a risk
management issue. In implementing the precautionary principle, it is
important to take into account all relevant information and not just
the potential harm that might result from inaction."

Professor Nigel Brown, head of the faculty of medicine and biomedical
sciences at the University of London, criticised the report, saying
the authors "verge on scaremongering". He said: "From their
assertions, the authors conclude that the combined evidence suggests
that neurodevelopmental disorders caused by industrial chemicals has
created a silent pandemic in modern society. This is a gross

"It is possible that there is a problem. We should be aware of this
and we should study the problem, but there is currently not a shred of
evidence of a pandemic."

Copyright 2006 News Limited