Daily Telegraph (UK), 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 system.

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 adolescence.

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 overstatement.

"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