Published online 3 November 2008 | Nature | doi:10.1038/news.2008.1202

News

Getting tough on makers of tiny tubes

Carbon-nanotube manufacturers need to notify the EPA before they start production.

nanotubeIt's official — carbon nanotubes are not graphite.Alamy

The US Environmental Protection Agency (EPA) has announced that companies intending to make or import carbon nanotubes must formally seek approval from the agency.

In a notice published in the Federal Register on 31 October, the daily publication for rules and notices of US Federal agencies and organisations, the EPA says that carbon nanotubes must be classed as new substances, and not just as carbon-based materials, such as graphite, that already exist on the Toxic Substances Control Act (TSCA) inventory.

The agency classed carbon nanotubes as 'new' under the TCSA in July 2007. But "very few people paid attention to that", says Andrew Maynard, chief science adviser to the Project on Emerging Nanotechnologies at the Woodrow Wilson International Center for Scholars in Washington DC. "There has been a tendency for companies to feel they don't need to do anything new with carbon nanotubes simply because they feel they can treat them as a form of graphite."

Putting a notice on the Federal Register is "a strong reminder" of the EPA's position, says Maynard, who co-authored a study showing that carbon nanotubes could cause the same kind of damage to lungs that asbestos causes1.

Richard Denison, senior scientist for the Environmental Defense Fund in Washington DC, agrees. "The EPA knows there is still considerable non-compliance with TSCA's notification requirements," he says.

Definition dilemma

Companies have to submit a Premanufacturing Notice (PMN) for the EPA to approve before going ahead with producing or importing any nanotubes.

"We saw a number of commercial sources of carbon nanotubes in this country and we had not seen PMNs," says Jim Willis, director of the chemical control division in the EPA's office of pollution prevention and toxics. If these companies do not come up with the required documentation, "we're very likely to follow up with enforcement initiatives if called for", he says. Penalties can be as high as US$25,000 per day for the duration of the violation.

But Maynard and other industry observers believe that the agency has not yet done enough to ensure that nanomaterials are properly regulated.

Terry Davies, now retired, who co-authored the original TSCA laws in 1976, says enforcing the submission of PMNs might not be enough. "TSCA is a very flawed act," he says. "One of its major deficiencies is that you're not required to put anything on the PMN apart from the name of the chemical."

It also isn't clear, he says, whether all carbon nanotubes will need to be registered. They come in many forms that can affect their properties and potential toxicity. But the definition used in TSCA of a new compound is one that has a different 'molecular composition' to any compound already registered.

Davies, Maynard and others have argued that any nanoscale material must be considered chemically and biologically different from the bulk material it is derived from. This is another weakness of the latest notice Maynard says — it is only applied to carbon, not to other nanoscale materials in wide use, such as titanium-oxide particles used in sunscreen.

Quick out of the blocks

One company that did comply was Swan Chemical from Lyndhurst, New Jersey, a daughter company of Thomas Swan in Consett, UK. Being one of the first to register carbon nanotubes puts Swan ahead of the game, says Chuck Van Fleet, president of Swan Chemical.

Swan has completed a PMN for a multi-walled carbon-nanotube product, Elicarb, that the company hopes will be used in ultra-strength composites and high-performance electronics. But Denison points out in his blog that even though Swan must now carry out an inhalation study of Elicarb, on rats, the results of these tests don't need to reach the EPA before manufacturing begins.

In Europe, carbon nanotubes are no longer seen as just another form of graphite. On 8 October, the European Commission's chemicals registration legislation, REACH, was changed so that carbon-based products, including nanotubes, were no longer exempt from the legislation. 

  • References

    1. Poland, C. A. et al. Nature Nanotech. doi:10.1038/nnano.2008.111 (2008).
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