mercredi, novembre 19, 2008

Attack of the Tiny Nano Particles - Be Slightly Afraid

Attack of the Tiny Nano Particles - Be Slightly Afraid
Report calls for more tests on 'wonder ingredient'
By Ian Sample
The Guardian / UK, November 15, 2008
Straight to the Source


Proliferation of nano materials could pose risk

The government must begin a "major and urgent" effort to assess the safety of nanomaterials, the tiny particles commonly used in products as varied as sun creams, sports clothing and medicine, leading experts warn today.

Hundreds of consumer products made with nanoparticles, which can be 100 times smaller than a virus, are already on the market, despite an almost complete lack of knowledge of the dangers they may pose to human health and the environment, according to a report by the royal commission on environmental pollution.

Nanoparticles have been embraced as a wonder ingredient across manufacturing industry. Cosmetic companies add titanium dioxide nanoparticles to sun creams to make them transparent instead of white. Sports clothing firms have introduced odour-free garments containing nanosilver particles that are twice as toxic to bacteria as bleach. The motor industry has added carbon nanofibres to car tyres and body panels to strengthen them. Many nanomaterials are so poorly understood that scientists are unable to predict how they will behave, and are unclear even how to check their safety, the report says.

Sir John Lawton, who chairs the commission, said the lack of tests and environmental monitoring for nanoparticles meant it was impossible to know if the materials were already a cause for concern. "Would we know if nanomaterials were causing harm? The answer is, no we wouldn't. We have no evidence that they cause harm, but a lot of that is because of a lack of evidence," he said. Professor Sir John Lawton on need to test nanotechnology Link to this audio

Industry figures estimate at least 600 products are already available globally that contain nanomaterials of some form, but that figure is expected to rise steeply.

The report warns that the proliferation of nanoparticles will see more of them released into the environment where they could be inhaled, discharged into water courses, and potentially introduced into the food chain with unknown consequences.

Lawton acknowledged nanoparticles were "exceedingly useful", but said there was "a major gap between the pace at which new nanomaterials are being developed and the generation of environmental health and safety data". Some scientists who gave evidence to the commission said it could be 20 years before sufficient safety measures were in place to monitor nanotechnology. "We don't want to be alarmist, but experience says the more we find out about this the better," said Lawton. "We're saying [to the government] get your finger out and get on and do something. This is really urgent."

Last week, the Royal Society expressed its dismay at the government's lack of action following its own report on nanotechnology in 2004, which also called for more stringent safety checks.

Nanoparticles lend their success to the extraordinary, and sometimes highly unusual, properties they have. For example, carbon nanotubes are incredibly strong, while pieces of graphite easily sheer apart. Nanoparticles of silver are significantly more toxic than lumps of the metal because the tiny particles have a huge surface area. The medical industry is investing heavily in nanoparticles to create precision drugs that can target specific tissues, such as cancer cells.

The report calls on government departments to back immediate research into toxicity tests for nanoparticles and the impact of nanomaterials in the environment.

The commission picks out three types of nanoparticle it says are of particular concern. Highly toxic nanosilver will inevitably get into the water supply when sports garments incorporating silver nanoparticles are washed. These could cause problems at sewage treatment works, which rely on beds of bacteria to purify water. Carbon nanofibres, which can be added to car tyres or woven into clothing to produce different colours without using dyes, are likely to be shed into the environment where they could be inhaled.

Finally, "buckyballs" - microscopic football-shaped cages of carbon - can be absorbed by simple organisms, according to the report, raising concerns that they could contaminate the food chain.

A spokesperson for Defra said: "As the commission states, it has found no evidence of harm to health or the environment from nanomaterials, but the government remains committed to researching their health and environmental impact." Backstory

Eric Drexler, an American engineer sketched the scenario whereby nanomachines no bigger than molecules run amok, consuming the planet's resources and leaving nothing but grey goo, in his 1986 book Engines of Creation. He has now dismissed that view, but more realistic concerns remain. Nanotechnology encompasses any material suited to measurement in billionths of a metre, or nanometres: connections in a chip, fibres in a tennis racket, or particles absorbing UV light in suntan lotion. Nanoparticles behave unlike lumps of the same material - stronger, more toxic, and with radically different electrical properties. What makes them so useful also makes their safety so uncertain.

© Guardian News and Media Limited 2008

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