The National Institute for Occupational Safety and Health has issued a new standard for limiting workers’ exposure to carbon nanotubes and nanofibers — a recommendation that is effectively the U.S. government’s benchmark.

In guidelines released this week, NIOSH offered a recommended exposure limit for workers at no more than 1 microgram per cubic meter of air. That’s basically at the threshold of what can be reliably detected in the air outside a laboratory setting.

A microscope image of carbon nanotubes, found in an air sample during a NIOSH site visit. (NIOSH Photo)

The agency, an arm of the federal Centers for Disease Control and Prevention, has been at the forefront of the effort to grapple with potential occupational health risks from a variety of nanomaterials, including carbon nanotubes and nanofibers. In December 2010, NIOSH released a draft version of these guidelines, setting the exposure limit at 7 micrograms per cubic meter of air; in 2011, the agency offered similar guidance on “ultra-fine” titanium dioxide.

While NIOSH has no regulatory power, the Occupational Safety & Health Administration and other federal agencies tend to use its recommendations as benchmarks, as does industry.

“This will become the letter for the industry,” said Charles Geraci, coordinator of the Nanotechnology Research Center at NIOSH.

Carbon nanotubes and fibers are super-strong, ultra-light and very small, and they’re turning up in a wide array of products, from airplanes to bike frames. But their small size means humans can inhale them, raising questions about the impact on the long-term health of people working with them every day.

Nanomaterials are becoming more and more common in consumer products, from nanosilver used as an antibacterial in socks to titanium dioxide in sunscreens. Academics and regulators are racing to answer crucial safety questions, but there are few hard-and-fast regulations that specifically deal with these super-small substances.

NIOSH, with its focus on worker safety, has been a lodestar. Part of the agency’s role is working with manufacturers to establish safe environments, and Geraci said he believes most companies are taking steps to protect their employees.

Geraci said the agency’s review of rodent studies convinced officials that there’s a good reason to be concerned about occupational exposure to these materials. The majority of the more than 50 studies reviewed “all came to a similar endpoint,” he said — that exposure to carbon nanotubes and nanofibers could cause chronic lung inflammation, followed by fibrosis, a scarring of the lung.

“That really caught our attention,” Geraci said, and was consistent with what NIOSH researchers were finding in their own studies.

Those studies include one announced last month, involving mice exposed to multi-walled carbon nanotubes through inhalation. The authors of the study, including Geraci, stressed that their findings didn’t suggest that the nanotubes can cause cancer on their own. But exposure to nanotubes can “increase the risk of cancer in mice exposed to a known carcinogen,” they wrote.

In light of the existing studies, and the history of other problematic “dusty” substances such as silica, NIOSH is eager to prevent any health problems. The goal of the new guidelines, Geraci said, is simple: Keep these materials out of the lungs of workers. The recommendations stress reducing exposure, either through respirators or other personalized equipment, or through workplace practices that keep the dusty substances away from workers. The agency is pushing manufacturers to move toward engineering better environmental controls, to lessen the need for respirators.

NIOSH is also recommending that companies monitor their employees for signs of pulmonary issues. Many firms already have this kind of testing in place, Geraci said, because they work with other potentially hazardous substances. He said the agency hasn’t seen or heard of any workers getting sick, but the industry is fairly young, and lung inflammation and fibrosis can take years to show up.

“We would rather not see any cases, of course, of pulmonary fibrosis,” he said. “That’s the whole idea of getting these protective measures.”

The new guidelines set the exposure limit lower than the 2010 draft, Geraci said, because the NIOSH risk assessment found that there could be health risks at an exposure somewhere between half a microgram and just above 1 microgram per cubic meter of air. Because of the difficulty in detecting levels below 1 microgram in an average workplace, he said, the agency decided to set the limit there.

“Going from 7 to 1 keeps us still within the range of needing to have good controls and good protection, so I think that’s a key message,” Geraci said. “Of course, we’d all like to have zero exposure.”

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Need another excuse to skip the powdered-sugar doughnuts?

An advocacy group’s testing of two national brands has come up with one reason that’s not about your waistline: super-small particles of titanium dioxide nestled amid the sweet coating. As You Sow, a non-profit group that lobbies companies to be more transparent in their dealings with the public on a variety of issues, released a report Wednesday outlining its test results.

Jacqueline Argote/Zach Behar Films Photo

After discovering titanium in nine out of 10 products tested, the group subjected Dunkin’ Donuts’ Powdered Cake Donut and Hostess Donettes to further scrutiny. Both products turned out to contain ultra-tiny nanoparticles of titanium dioxide, which is used as a whitening agent in everything from paint to toothpaste. And, apparently, doughnuts.

The U.S. Food and Drug Administration categorizes the larger version of titanium dioxide as “generally regarded as safe.” But some scientific research suggests nanoscale particles could be problematic if eaten, because they can pass through the intestine and into the bloodstream.

The report also highlighted the dismal response of food companies to a survey aimed at discerning who’s using nanoparticles in food or packaging.

The group sent the survey to 2,500 companies, including processors, retailers, fast-food purveyors and makers of nutritional supplements. Only 26 companies responded — and many of them said they didn’t know whether nanoparticles were in their products.

Juxtaposed with this corporate reticence is another study, released last year, which found nanoscale titanium dioxide in a slew of consumer products, including food items such as Betty Crocker Whipped Cream Frosting, Trident gum and M&M’s candies.

Andy Behar, As You Sow’s CEO, said the unlabeled presence of nanoparticles in common snack food — a presence that is perhaps unknown even to the manufacturers — together with the companies’ unwillingness to discuss their practices shows the need for better testing and more accountability. The group hopes to use the new report to raise money to test additional products.

“We’re just trying to bridge the gap, to make sure that a light is shined on it and there’s an open transparent conversation,” Behar said. “We believe things should be proven safe before we put them in our food.”

Behar said that kind of approach would be more like Europe’s, where there is a more intense effort to identify, label and test nanomaterials that are on the market. The European model is largely based on the so-called precautionary principle — essentially, knowing and evaluating the risks before bringing a products to market.

But some of those efforts have been criticized as far too sweeping, and American manufacturers are largely resistant to nano-specific regulations, especially any that adopt the precautionary principle.

In the U.S., Behar said, there’s a need for more testing of actual products on store shelves, in tandem with scientific research examining whether certain nanoscale substances pose a real risk to people, animals and the environment. With better information, consumers can make real choices, he said.

“We’re not taking a stance that nano is bad, we’re just saying there’s no information,” he said.

Last spring, the FDA announced that it wouldn’t automatically extend the “generally regarded as safe,” or GRAS, designation to nanoscale versions of substances that are already on the list. The agency also asked manufacturers to come in and discuss their use of nanomaterials, as a way to get a handle on what’s going on in the food sector.

As You Sow has pressed companies to talk about how they’re using nanoparticles, which are often touted as the way to make fat-free ice cream taste more like Haagen-Dazs or create packaging to keep food fresh for long periods. But with so many resisting, the organization is turning some of its focus on consumers, Behar said.

“Now we feel like we have to start talking to the public, because the public needs to know that this is an issue, this is real, this is going on,” he said.

For example, Behar said, consumers, not government regulators, drove the movement away from using Bisphenol A in plastic containers made for babies and children.

“If companies feel that their customers want something, they may react to it,” he said.

With that in mind, As You Sow is trying to to raise $9,000 to test three more snacks: a frosted version of Kellogg’s Pop Tarts, Trident and M&M’s.

Titanium dioxide is widely used, at both the nano and larger scale. The super-small version has become particularly popular in sunscreens, since the titanium dioxide acts as a physical sunblocker while appearing transparent on the skin. It’s also turning up as stain-resistant paint, cosmetics and toothpaste.

But the properties that make the substance appealing may also be the root of health and environmental risks. Because of their tiny size, nanoparticles can move around the body more easily, and can be more difficult to remove from wastewater. Even as companies and scientists race to develop new applications for nanomaterials, other researchers — and regulators — are scrambling to suss out what, if any, problems might arise from adding these substances to workaday items.

Super-small titanium dioxide, for example, has been categorized as a “potential occupational carcinogen,” by the National Institute for Occupational Safety and Health, which recommended that employers protect workers from exposure.

Titanium dioxide nanoparticles do seem to migrate through the intestines, said James Faust, a research scientist at Arizona State University.

“If they are transported through the gut into the bloodstream, they could go to other organs,” he said.

In another study, when rainbow trout were fed titanium dioxide nanoparticles, the substance accumulated in several places, including the gut, spleen and brain. The dose didn’t affect growth, but the particles didn’t clear the brain, researchers found.

Faust said titanium dioxide nanoparticles also seem to prompt changes to the gut itself. The end result might not be directly harmful, but could affect how people absorb nutrition through the intestine.

In addition, Faust said, there’s significant evidence that the type of titanium dioxide being used, and especially its crystalline structure, has an impact on toxicity. But it’s almost impossible to know what type of the material is being used without a sophisticated laboratory test.

“It’s hard to say ‘some of them are OK, go ahead and eat them,’ and others are not,” Faust said. “There just needs to be a lot more research.”

That’s exactly what As You Sow is pushing for. Some of the doughnuts the group found to contain titanium dioxide didn’t even list the ingredient on the label, something the organization plans to complain to the Federal Trade Commission about. Beyond that, Behar said, the group wants the government to take broader action.

“We want the FDA to move on this. We want the FDA to actually invest in some science and to look at what Europe’s doing,” Behar said. “I just think Europe starts with the precautionary principle, and we just start with the assumption that everything is safe — until people get sick.”


In findings that could  impact both the cosmetics industry and the debate over a newer breed of sunscreens, British researchers have found that super-small nanoparticles don’t deeply penetrate the tough barrier of pig skin.

Scientists at the University of Bath dosed pig skin with fluorescent polystyrene nanoparticles suspended in water. (Pig skin is considered a good stand-in for human skin.)Their results, published recently in the Journal of Controlled Release, found the particles didn’t get beyond the outermost layer of skin.

The findings held up even when the skin had been roughed up a bit, at least theoretically making absorption of the nanoparticles easier.

In an email, Richard Guy, a Bath professor and one of the paper’s co-authors, said the group used a water-based exposure method to make it as likely as possible that the nanoparticles would be absorbed by the skin. While the team tested only polystyrene nanoparticles — ranging in size from 20 nanometers to 200 nanometers — Guy said he saw no reason to think that other substances of the same size range would behave all that differently.

Cross-sections of pig skin after dosing with various sizes of polystyrene nanoparticles and water. (Image credit: Journal of Controlled Release)

The experiment, which sought to help settle the ongoing debate over whether nanoparticles can be absorbed through the skin, could help answer some major questions about safety and efficacy. One set of questions involve whether cosmetic applications, such as gold-laden moisturizers, actually deliver what they claim by getting beyond the top layer of skin. Another line of inquiry is whether so-called “mineral” sunscreens that contain ultra-tiny titanium dioxide and zinc oxide pose any safety threat through absorption.

So far, the science has been mixed where sunscreens are concerned: FDA researchers, who also used pig skin, found little penetration by nano-sized titanium dioxide in sunscreen.  But scientists in Australia, who applied sunscreens with nano-sized zinc oxide to human skin, did detect zinc in the blood of test subjects — although at very low levels. The confusion has prompted some consumer advocates to push the FDA to take a closer look at these sunscreens.

The situation is even muddier when it comes to cosmetics. Nanoparticles are increasingly common in the ever-escalating race to bottle beauty, although it’s unclear (as with most ingredients that promise to “revive” aging skin) how effective these formulations are. A study released last year found that neither dermatologists nor their patients knew much about nanomaterials, but the dermatologists found them promising nonetheless.

Knowing that nano-sized gold or other substances don’t get far down into the skin could alleviate some safety concerns — but also undermine claims of rebuilding skin from the inside out.

Of course, questions about nanomaterials in cosmetics and sunscreens — along with a host of other products — go beyond whether they’re getting under our skin. Scientists are also concerned about what happens when these substances wash off people and into the water as well as the possibility of swallowing some of these formulations, especially where children are concerned.

But it has been the absorption issue that has grabbed the most attention.

In his email, Guy said without studying every nanomaterial — something he and his co-authors have no plans to do — it’s “impossible to give an unequivocal answer” to the question of whether these results can be construed as indicative of how other substances might behave. But, he noted, human beings have naturally-occurring nano-sized particles inside their bodies (such as some types of proteins), many just under the skin. Those substances, he said, don’t regularly pop out.

“The only way to make that happen is to poke a hole in the barrier or to cut it!” Guy wrote.

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ALBANY, N.Y. — As questions swirl about the safety of using super-small particles in everything from breakthrough medical treatments to sunscreens, a new goal has emerged: Take the bad out, and keep the good, at the earliest building-block level.

It’s a great idea in theory. But can it work in practice? Recently, officials from the National Institute for Occupational Safety and Health pulled scientists, industry representatives and advocates for workers and consumers together to try and answer that question.

According to the organizers — trailblazers in the effort to protect workers from risks associated with nanotechnology — the three-day meeting was the first time such a wide swath of interests had convened in one place.

“We are succeeding in bringing two communities together that really need to start a dialogue with each other,” said Charles Geraci, who heads NIOSH’s Nanotechnology Research Center.

The concept of engineering out harmful effects has become a movement, known as green chemistry, in academic research, and NIOSH has its own Prevention through Design program.

Still, any effort to design a safer nanoparticle is hamstrung by the same challenge facing regulators: What, exactly, makes a nanomaterial dangerous?

Over the course of the three days at the University at Albany’s College of Nanoscale Science and Engineering, several themes emerged, many of them familiar to those who work in the development of nanotechnology-enabled products.

Of primary concern is what they don’t know. Scientists have made progress in understanding these materials, but many of those leaps have raised as many questions as they answer. And big gaps remain, prompting repeated calls for close scrutiny of particular substances.

A second prong of the discussion focused on the differences between a “pure” nanomaterial and one that’s been blended into a product, like a carbon nanotube-strengthened bike frame or a super-whitening paint laced with titanium dioxide. Often, scientists are finding key diferences between a laboratory version of a substance and what’s in a tube or a fabric.

“Nanomaterials don’t exist only in vials; they exist in products,” said James Hutchison, a professor and prominent researcher at the University of Oregon.

The final point of emphasis was another familiar refrain. Communication — between government, industry, unions and consumers — is vital.

Bill Kojola, an industrial hygienist at the AFL-CIO, said the history of worker safety has been “prevention, maybe — after the fact.” That can’t be the way it goes with nanotechnology, or a whole host of other so-called emerging technologies, from genetically-modified organisms to bioengineering.

The biggest challenge, Kojola said, is to get out in front of potential problems. Regulators and manufacturers can’t wait for epidemiological studies that take years to identify health problems, he said.

“If we do that, we’ve failed the workers,” he said. “We need to protect workers where the information is incomplete.”

That protection includes anticipating not just the sunniest workplace scenario, Kojola said, but also what could happen in an accident.

“Obviously, you can’t turn over every rock, but you need to turn over some big rocks to make sure you’re addressing at least the more likely scenarios,” he said.

For several years, Geraci and his colleagues at NIOSH have been working with companies to identify potential workplace safety issues and find ways to curb them. The agency, an arm of the Centers for Disease Control and Prevention, has issued a draft guideline for occupational exposure limits to carbon nanotubes and super-small titanium dioxide and has proposed exposure studies of workers who handle carbon nanotubes and nanofibers.

The NIOSH work, and that of academic groups that are also studying good workplace practices, have helped manufacturers come up with their own rules.

Mark Banash, vice president of quality and regulatory affairs at Nanocomp Technologies, Inc. said his company has worked to refine its manufacturing techniques to avoid exposing workers to anything dangerous. Nanocomp uses lots of carbon nanotubes, to make sheets, yarns and panels that strengthen everything from military aircraft to snowboards.

Carbon nanotubes, which are super strong but feather light, are of particular concern because they’re small enough for people to breathe them in, and because certain types have been shown to cause lung inflammation, often a precursor to cancer. There have been inevitable comparisons to absestos and other superfine substances that cause lethal disease. While most nanotubes are thought to be solidly embedded in products, it’s the two sides of the life cycle — manufacturing and disposal — that has scientists and regulators worried.

Banash said Nanocomp is concerned, too, and has developed manufacturing techniques aimed at minimizing risk. For example, instead of working with powders — in which carbon nanomaterials are easily respirable — the factory now forms sheets or yarns of its composite material, ensuring that the tiny particles are completely encapsulated.

Contracts with the government and big companies has added another layer to Nanocomp’s safety priorities, Banash said. For example, DuPont sends in its own safety watchdogs to make sure the company is doing a good job. Questions from local officials have also forced the company to solve problems, he said.

“This is real. This is dealing with the water department,” Banash said. “You have to worry about the fire department … you have to worry about wastewater treatment.”

Another manufacturer, QD Vision, makes quantum dots, which are typically loaded with cadmium, a toxic heavy metal. Seth Coe, the company’s co-founder and chief technology officer, said this creates problems for waste disposal — a thorny issue when you’re trying to break into the television and lighting markets. Coe said that while studies have shown there’s almost no release of cadmium from quantum dots, QD Vision is working to develop a way to make them without cadmium or lead.

Pressure to be safe is coming from other areas too, if not explicitly from government regulators, said Lynn Bergeson, a partner at the Washington law firm Bergeson & Campbell LLC who works with nanotechnology companies to navigate the regulatory process.

“The new sheriff in town is not the EPA,” Bergeson said. “It is the entities that will decide to market your product” because they’re comfortable with the safety angle. On the list, she said, are retailers like Whole Foods, which rely on the “green” label for much of their cachet, and Walmart, which can’t afford to sell products associated with any safety questions.

These forces leave advocates, regulators and industry facing a tough task. Donna Heidel of NIOSH, one of the meeting’s organizers and coordinator of the Prevention through Design program, said she plans to push for more case studies of particular materials and further discussions between these varied interests.

“Prevention through design is not about regulation,” she said. “It’s about demonstrating the value of worker safety.”

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