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segunda-feira, 13 de agosto de 2012

Nanoparticles: A tiny question of safety

A University of Sherbrooke student cleans lab equipment used to feed raw material into a nanoparticle reactor, which converts it into nano-size particles. The lab has been renovated to make it safe for working with nanoparticles and other chemicals.
A University of Sherbrooke student cleans lab equipment used to feed raw material into a nanoparticle reactor, which converts it into nano-size particles. The lab has been renovated to make it safe for working with nanoparticles and other chemicals.
Photograph by: Martin Blanche , University of Sherbrooke

If you have Robert Schiestl over to your house, don’t be surprised to see him peeking at ingredient labels on things in your kitchen or bathroom.
He can’t help it. Schiestl, a leading U.S. cancer expert, instinctively reads the label before he buys or uses a host of products — any food that’s partly white, toothpaste, sunscreen, shampoo, over-the-counter medicine.

He’s trying to avoid nanoparticles, which a growing pile of studies say may cause cancer, damage to organs and skin, Crohn’s disease and environmental pollution.

Labels in Canada and the U.S. don’t have to say whether a product contains nanoparticles — so to be completely sure, Schiestl avoids all products with two ingredients that are increasingly used in nano-form: titanium dioxide and zinc oxide.

The tiny particles causing the concern are as little as 10,000 times the width of a human hair and are measured in nanometres, or billionths of a metre.
They’re part of a revolutionary technology that’s been touted as “the most powerful tool the human species has ever used” — giving us the ability to build anything we can conceive molecule by molecule, and potentially leading to healthier lives and cleaner energy.

Governments, eager to get on the nanotechnology bandwagon, have shovelled huge public subsidies into nanotech in the past decade, fuelling its growth into a $250-billion-per-year global industry that is expected to grow to $3 trillion by 2015.

The subsidies have helped promote the use of nanoparticles in thousands of goods — everything from food colouring to scratch-resistant coating on eyeglasses and anti-bacterial agent in clothes.

Nanotech has even answered the age-old problem of getting ketchup out of the bottle. In 2007, German scientists developed a super-slippery nano-coating for bottles that lets ketchup slide out more easily.

Yet, more than a decade after nanoparticles started being widely used in consumer products, they are still subject to virtually no regulation in Canada, and little is known about their health impacts.

Some governments are starting to act. In April, the U.S. Food and Drug Administration issued draft guidelines that would require companies to do safety tests on nanoparticles in food and cosmetics.
And across the Atlantic, the European Parliament voted in 2009 to recommend a moratorium on nanoproducts in food until rigorous safety testing was done.

Europe has since adopted regulations requiring companies to disclose nanomaterials in products, test their safety and label food containing nanomaterials starting in 2014 and cosmetics in 2013.

But without more action, Schiestl says, we may be headed toward a nanotech train-wreck.
“(Some nanoparticles) could have the same impacts as asbestos,” said Claude Ostiguy, a chemist and nanotech expert at the Quebec government’s workplace safety research institute.

“The public is poorly informed.”

Nanoparticles, because they’re so minute, can cause health problems by penetrating deeply into the lungs, skin, blood, brain and, in pregnant women, the placenta, says Pat Mooney, executive director of ETC Group, a non-profit tech watchdog in Ottawa.

Researcher and author Mooney first raised questions about health dangers from nanoparticles a decade ago, calling for their ban in food and other consumer products until more is known about their safety.
“We were told we were nuts. We got this blank stare of shock, saying, ‘Why could you possibly think this is a risk?’

“Now virtually no one is saying that. Study after study is saying this is not fine,” ” said Mooney, a Pearson Peace Medal winner who was one of four National Research Council Canada panellists to weigh in at the June 2011 public forum discussing: Are consumer products made with nanotechnology worth the risk?

Schiestl, a professor of pathology and radiation oncology at UCLA’s School of Medicine, echoes the moratorium call. “There is no reason why it’s in food, drugs or cosmetic products. It should be banned,” he said.

Schiestl was one of the first scientists to study the health risks from one of the most common nanoparticles, titanium dioxide.

With 5 to 10 million kilograms produced worldwide each year, nano-titanium dioxide has been touted as a miracle material and is widely used in food, toothpaste, shampoo and paint (as a whitener); in sunscreen (for its anti-UV properties); and in medicine and vitamin capsules (as non-medicinal filler).

But in a study Schiestl co-authored in the journal Cancer Research in 2009, mice that drank water with titanium dioxide nanoparticles suffered DNA and chromosomal damage, which could lead to cancer.

Schiestl, who is also a researcher in UCLA’s Jonsson Cancer Center, said his findings prompted him to avoid all products with titanium dioxide or another common sunscreen ingredient, zinc oxide, which also often comes in nano-sized form.
“I look at labels on everything. If it contains titanium dioxide or zinc oxide, I don’t buy it. I think they should definitely be avoided,” he said.

There had already been earlier warning signs about titanium dioxide nanoparticles.
In 2006, the World Health Organization’s cancer research agency declared titanium dioxide of all sizes (regular size and nano) to be “possibly carcinogenic to humans,” citing studies that found that inhaling it in nanoparticle form caused rats to develop lung cancer, while mice suffered liver damage after the nano version was injected it into their stomach.

The federal Canadian Centre for Occupational Health and Safety followed suit later in 2006, also declaring titanium dioxide to be a carcinogen, particularly in dust form.
Both bodies noted that studies to date hadn’t shown adverse effects on humans working with titanium dioxide, but the WHO said more study is needed, especially of the nano version.

But Schiestl’s study was the first to show nano-titanium dioxide causes cancer risks if ingested.
Schiestl’s concerns were reinforced in May when scientists warned that zinc oxide nanoparticles present in many sunscreens could cause skin damage.

Human cells exposed to the nanoparticles deteriorated “dramatically” when placed under ultraviolet sunlight, said Yinfa Ma, a chemistry professor at the Missouri University of Science and Technology, in a press release.

“Zinc oxide (in nano form) may generate free radicals (a type of unstable molecule) when exposed to UV (ultraviolet) sunlight, and those free radicals can kill cells,” Ma said.
Another effect could be cancer, said Qingbo Yang, a graduate student working with Ma.
“(The free radicals) might totally ruin the cellular respiratory system, which will cause cell death, or bring chronic damage (inside cells), which may cause irreversible cell function loss or even cancer,” Yang said in an email.

Nano enthusiasts have touted civilization-changing potential uses — cancer-killing medicines, improved solar panels, super-fuel-efficient cars and planes. Health applications being studied include using nanoparticles or “nanorobots” to deliver drugs and, for example, engineering them so they specifically target cancer cells; and using nanoparticles in diagnostic equipment to detect diseases.

“Nanotechnology is the key to answering many of the key global issues facing us — energy, the environment, water purification, health. It’s all potentially solvable,” said Lori Sheremeta, an adviser to the $52-million, state-of-the-art Edmonton-based National Institute for Nanotechnology, which funds nanotech research with money from Ottawa, the Alberta government and the University of Alberta.

But most of the promised efficiency gains have yet to materialize, according to a 2010 analysis by environmental group Friends of the Earth.
And it turns out nanotech itself can be a huge energy sinkhole. A kilo of carbon nanotubes — used to strengthen baseball bats and hunting bows — requires an estimated 167 barrels of oil to make, said Friends of the Earth.

Carbon nanotubes are “one of the most energy intensive materials known to humankind,” according to a 2010 report to a symposium of the U.S. Institute of Electrical and Electronics Engineers.

That report said many nanoproducts remain profitable largely because of enormous government subsidies to the nanotech industry — $65 billion globally so far, with $150 million spent by Ottawa on nanotech research in 2009 (the latest year for data).

In reality, most nanotech uses have turned out to be fairly mundane.
Health and fitness products (like personal care items, cosmetics and clothes) account for 56 per cent of the 1,300 products using nanoparticles known to be on the market globally (up six-fold from 212 products in 2006), according to the Project on Emerging Nanotechnologies, a Washington, D.C., non-profit that maintains an inventory of nanoproducts.
The clothes category includes “anti-odour socks” coated with anti-bacterial nano-silver, which don’t have to be washed as often.

(The inventory is based on industry self-reporting, so the actual number of nano-products is thought to be much higher — possibly as much as 10,000 in the personal care category alone, according to a 2006 report from the Environmental Working Group.)

Food, beverages and food packaging make up another 8 per cent of nanotech products.
Nano-coating could even be on your produce. Food exporters in Latin America were found to be spraying a waxlike nano-coating on fruit and vegetables bound for the U.S. and Canada to extend their shelf life, a U.S. government scientist was quoted saying in an AOL News investigation in 2010.

“Nanoparticles are extremely widespread. Everybody is exposed to them to some extent,” Schiestl said.

Meanwhile, health concerns from nanotech also keep piling up. Studies have found:
Nano-titanium dioxide could be contributing to Crohn’s disease because of its use in food and drugs, a 2002 study found. Crohn’s rates have shot up among children in Canada (which has some of the world’s highest rates), the U.S. and Europe in the past 10 to 20 years.

Socks with nano-silver lost up to half of the nanoparticles into water when washed, a 2008 study found — raising concerns about impacts when the waste water hits the environment.
Titanium dioxide nanoparticles exacerbated eczema in mice, a 2009 study found, noting that eczema rates have risen in the developed world.

Some of the worst risks may face people who work with nanoparticles.
“Workers, if they are not working carefully, can be exposed to large amounts,” said Ostiguy, the Quebec workplace safety expert.

“There is no regulation of nanoparticles in Canada. There is virtually nothing for workers (handling nanoparticles) and even less for consumers.”

Ostiguy wrote Quebec’s first guide to best practices for handling nanoparticles in workplaces in 2009. The guidelines are voluntary.

An estimated 2,000 workers in Quebec could be exposed to nanoparticles on the job.
And don’t expect nano-workplace regulations any time soon, Ostiguy said.

“It’s almost impossible to determine norms for the workplace,” he said, noting that toxicity studies are still needed for hundreds of types and sizes of nanoparticles before regulations can be developed.

Anxious about the gaping safety holes, the International Union of Food, Farm and Hotel Workers in 2007 called for a moratorium on commercial uses of nanotechnology in food and agriculture.

The stakes were underlined in 2009 when two Chinese factory workers died and another five were seriously injured in a plant that made paint with nanoparticles. Working with poor ventilation and little protective gear, all seven workers developed lung disease and rashes on their face and arms. Nanoparticles were found deep in the workers’ lungs.

Back in Quebec, some workplaces are acting. At the University of Sherbrooke, chemical engineering professor Gervais Soucy has worked with nanoparticles for about seven years.
After hearing about Ostiguy’s best-practices guide, he embarked on a year-long, $300,000 renovation of his lab to make it safe for using nanoparticles and other chemicals.

Companies that work with nanoparticles have the responsibility to do so in a safe way,” Soucy said.

But the safety questions don’t seem to be resonating in Ottawa.Canada still lacks any nanomaterial-specific regulations six years after the WHO and Canadian Centre for Occupational Health and Safety raised cancer concerns about titanium dioxide, particularly in nano-form.

It’s also been four years since a blue-ribbon panel of 15 nanotechnology experts said in a report that Canada “urgently” needed to strengthen regulations on nanotechnology and study its safety.

Health Canada refused to grant an interview for this story. Spokesman Gary Holub acknowledged that Health Canada doesn’t know which products on the market in Canada contain nanomaterial, but he said they’re safe.

“There is no evidence to suggest that nanomaterials pose a risk to Canadians,” he said.
But Sheremeta of the Edmonton nanotech institute says we know so little about all the nanoparticles out there and we don’t know what the possible health risks are, whether for consumers or workers — and we’re years away from having enough safety research.

“If there is an international effort with significant resources, we could start having some important information in hand within 10 years,” she said, noting that such an effort has yet to start. “It’s very frustrating.”

Schiestl, for his part, is anxious to study nanoparticles more, but despite the billions for nanotech research, he said he can’t get any funds — and government officials don’t seem interested in his findings.

“I haven’t heard of a single government agency that was interested in this study. What surprised me is nobody does anything about this.”

How nanoparticles are made
Nanoparticles are made by burning or crushing regular substances like titanium, zinc or silver until they become an ultrafine dust. The dust is then mixed with other ingredients in a product or applied as a coating.

In nano-size, the substances often acquire surprising new traits—different electrical conductivity, elasticity, opacity, even colour. Nano-gold, for example, can be red or blue, depending on the size of the particles.

“It’s almost like multiplying the periodical table,” says Pat Mooney of ETC Group, a tech watchdog non-profit in Ottawa.

Fonte: The Montreal Gazette