The National Institute for Occupational Safety and Health (NIOSH, a part of the Centers for Disease Control) will be accepting comments until February 18, 2011, on its draft “Current Intelligence Bulletin” regarding occupational exposure to carbon nanotubes and nanofibers.*
Though, as the bulletin reports, there are currently no reported “adverse health effects in workers producing or using carbon nanotubes (CNT) or carbon nanofibers (CNF),” some studies on rodents have shown effects such as “the early onset and persistence of pulmonary fibrosis [...] in CNT-exposed animals,” “reduced lung clearance in rats exposed to low mass concentrations of CNT,” and “acute pulmonary inflammation and interstitial fibrosis […] in mice exposed to CNF.”
It is because of such findings that NIOSH is proposing a recommended exposure limit (REL) of 7 μg/m3 elemental carbon (EC) as an 8-hour time-weighted average. The bulletin goes on to make additional recommendations for dealing with CNT and CNF in the workplace, such as how to store and handle the materials, as well how to clean areas where such materials are used. You can read a succinct summary of the draft in this Fulbright & Jaworski briefing.
But NIOSH isn’t the only agency worried about nanomaterials. According to the EPA, many nanoscale materials are regarded as “chemical substances” under the Toxic Substances Control Act (TSCA). The EPA has been working towards comprehensive regulation of nanomaterials under TSCA, using a “four-pronged approach” that is detailed here.
In fact, only a few months ago, the EPA published a final rule in the federal register requiring anyone intending to manufacture, import, or process either multi- or single-walled carbon nanotubes to notify the EPA at least 90 days before commencing such activities. This pre-manufacture notification (one of the aforementioned four prongs) gives the EPA an opportunity to determine whether the proposed use should be prohibited or limited, as “these chemical substances may be hazardous to human health and the environment.”
* Nanomaterials are generally defined as structures sized between 1 to 100 nanometers**
** A nanometer is equal to only one billionth of a meter