毒上腦

Study finds toxic chemicals linked to autism, ADHD

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Leading chemical experts are calling for a radical overhaul of chemical regulation to protect children from everyday toxins that may be causing a global ''silent epidemic'' of brain development disorders such as autism, dyslexia and attention-deficit hyperactivity disorder.

A review published in The Lancet Neurology on Saturday said current regulations were inadequate to safeguard foetuses and children from potentially hazardous chemicals found in the environment and everyday items such as clothing, furniture and toys.

Philippe Grandjean from Harvard School of Public Health in Boston and Philip Landrigan from Mount Sinai School of Medicine in New York said that, in the past seven years, the number of recognised chemical causes of neurodevelopmental disorders doubled from six to 12.

These include lead, arsenic, pesticides such as DDT, solvents, methylmercury that is found in some fish, flame retardants that are often added to plastics and textiles, and manganese - a commonly mined metal that can get into drinking water.

The list also controversially includes fluoride, a mineral found in water, plants and toothpaste.

Many health authorities including the World Health Organisation and Australian governments say low levels offluoride in drinking water is safe and protects teeth against decay, but Dr Grandjean and Dr Landrigan said a meta-analysis of 27 studies, mainly from China, had found children in areas with high levels of fluoride in water had significantly lower IQ scores than those living in low-level fluoride areas.

Dr Grandjean and Dr Landrigan said that, since 2006, the number of chemicals known to damage the human brain more generally, but that are not regulated to protect children's health, had increased from 202 to 214.

Of the newly identified toxins, pesticides constitute the largest group. The pair said this could be the tip of the iceberg because the vast majority of the more than 80,000 industrial chemicals widely used in the United States have never been tested for their toxic effects on the developing foetus or child.

They said one of the barriers was the logistics of studying the impact of such chemicals on children's brains to meet the "huge amount of proof required" before regulation such as banning a chemical was enacted.

"The only way to reduce toxic contamination is to ensure mandatory developmental neurotoxicity testing of existing and new chemicals before they come into the marketplace," Dr Landrigan said.

They proposed a new international prevention strategy that would put the onus on chemical producers to demonstrate that their products are low risk using a similar testing process to pharmaceuticals. They also proposed a new international regulatory agency to co-ordinate these measures.

Professor Ian Rae, who advises the United Nations Environment Program, said authorities in Australia, Canada and Japan were already working on better data for chemicals introduced without the kind of testing required now.

''Our National Industrial Chemical (Notification and Assessment) authority is prioritising the 38,000 chemicals on the Australian list and generating assessments for those of greatest concern,'' he said.

Oliver Jones, a lecturer in analytical chemistry at RMIT University, said many of the chemicals listed in the review were already strictly controlled or banned in Australia and that, where they are used, it was not "for fun or with malice but to save lives".

"DDT helps stop the spread of malaria, flame retardants reduce deaths from fires in the home and manganese is a required trace element for all living organisms," Dr Jones said.

"In addition, testing every single chemical in use for every possible affect is impossible. That said, we should never be complacent and more reasoned debate and research into best practice of the management of chemicals is very welcome."

(16/2/2014 Sydney Morning Herald)

標少的醫學常識有限，但對於健康方面的文章會留意一下。《刺血針》(Lancet)這篇有關化學毒素影響孩童腦發展的文章也算駭人。原文太長，所以採用了報章的報導。有毒化學物料對人體的損害，個人可以做的很有限，衣履鞋袜及家具中含有這種物質，任憑你化學常識豐富，也無從監察。最駭人聽聞的是在食水中的氟對孩童智力的影響，如果保護牙齒防蛀的同時，會減弱智力，這平衡點怎拿揑呢？下面這段是原文相關的論述：

A meta-analysis of 27 cross-sectional studies of children exposed to fluoride in drinking water, mainly from China, suggests an average IQ decrement of about seven points in children exposed to raised fluoride concentrations.44 Confounding from other substances seemed unlikely in most of these studies. Further characterisation of the dose—response association would be desirable.

(A paragraph taken from Neurobehavioural effects of developmental toxicity, THE LANCET Neurology)

含氟量高的食水會減低智商7點，常人也變低智了。我不知道刷牙多擠牙膏會不會做成影響，我一向都擠很少，約一粒紅豆那樣多，因為牙醫常説牙膏不用多，所以我一枝牙膏長擠長有。這種無聲的疫病(silent epidemic) 恐怕是 pandemic了。

我在市埸間中會見到很新鮮的劍魚，價廉物美，但我總記得提醒家中有孕婦及孩童的人不要吃，因為劍魚含甲基水銀(methylmercury)量驚人，大條的馬駮及鯊魚也有同一問題。在海洋沉積層的水銀，由微生物轉變成甲基水銀。就算不是孕婦小孩，也不能時常吃深海大條的魚，尤其是劍魚，以免水銀在血液中積聚。

我不想特別長夀，只想健康，這些毒素已經不會使我成為自閉(autistic)，表現過度活躍(ADHD)或者有讀寫困難(dyslexia)。希望家中有即將懐孕或已懷孕婦女及孩童的人，有所注意。