Tests showing potential human toxicity and carcinogenicity, as well as environmental damage, have resulted in new rules for certain nanoparticles. On February 12, 2014, the U.S. Environmental Protection Agency (EPA) issued significant new use rules (SNURs) for 35 substances including four varieties of multi-walled carbon nanotubes as well as infused carbon nanostructures. [i] The principal purpose of a SNUR under the Toxic Substances Control Act (TSCA) is to ensure that all manufacturers, importers and processors of the same chemical substance are subject to similar requirements. The deadline for comments on the proposed SNUR was March 14, 2014. The EPA docket indicates that no comments were received regarding the proposed regulations on nanoparticles. Therefore, the final rule will take effect on April 14, 2014.
The SNUR controls the manufacture, use and importation of four types of multi-walled carbon nanotubes (PMN Numbers P-12-416, P-12-417, P-12-418, and P-12-419) which were already subject to a “risk-based” consent order under §5(e) of the TSCA. These types of carbon nanotubes are commonly used as an additive in semiconductor packaging and electronic devices, in batteries and solar cells, as a lightweight stabilizer in automobile parts and windmill blades, to reinforce building frames and machine components, in heating elements, lighting and x-ray applications, and for thermal emission and shielding in electronic devices. In addition, these nanotubes may be used in chemical manufacturing processes and as a filter additive to remove nanoscale materials. However, the SNUR will not apply to substances compliant with the pre-manufacture notice requirements where the nanocompounds have been completely reacted (cured); incorporated or embedded into a polymer matrix that itself has been completely reacted (cured); or imbedded into a permanent polymer form that is not intended to undergo further processing.
The EPA’s basis for regulating these substances includes test data showing pulmonary and cardiovascular toxicity, fibrosis and carcinogenicity. When there is potential dermal contact with the nanosubstances at issue, the SNUR requires use of personal protective equipment including gloves and protective clothing. Additionally, when there is potential inhalation, the SNUR mandates use of a NIOSH compliant respirator. Furthermore, the SNUR outlines several tests that manufacturers should undertake to help categorize the human health effects of the regulated nanotubes, including a 90 day inhalation toxicity test with post exposure observation of up to three months. For further information, see 40 CFR 721.10703.
The EPA also noted concern about the possible release of carbon nanotubes into the water supply, citing a study observing adverse effects of carbon nanotubes on rainbow trout at exposure levels less than ten parts per billion. As a result, the SNUR prohibits any use of the substances that would result in surface water releases.
The SNUR also regulates another form of nano material, infused carbon nanostructures (P-12-576), which are used as an additive to composite materials to provide conductive properties and reinforcement. The EPA has identified risk-based concerns for lung effects when the infused carbon nanostructures are not used in a controlled manufacturing process. The EPA has recommended further testing of this substance, including gathering more specific information regarding the physical-chemical properties of the carbon nanostructures. For further information, see 40 CFR 721.10706.
The EPA’s new steps to protect workers from inhalation exposure to nanoparticles may discourage some companies and end-users from accepting nanotechnology enabled products, particularly where OSHA and NIOSH are already taking measures to regulate in this area. With the onus on the manufacturer to ensure SNUR obligations are communicated to (and followed by) customers, some manufacturers may be apprehensive about the risk of incurring EPA fines and penalties if respirator use restrictions are not followed in downstream manufacturing processes. In addition, the downstream manufacturer may be more familiar with OSHA obligations and less adept at complying with the EPAs recordkeeping requirements for materials covered by a SNUR. As a result, it is questionable whether the EPA’s action will lead to an improvement in worker protection over the recommendations in the OSHA and NIOSH guidance documents.
Another complication of the EPA’s action is that some businesses using the materials will not know whether they are dealing with regulated types or amounts of nanosubstances. To protect confidential intellectual property, the EPA identifies nano engineered carbon compounds based on generic structural terms to protect the confidential chemical identities of the substances. Because these nanoparticles are included on the confidential inventory, the regulated substance will be identified as “multi-walled carbon nanotube” together with PMN numbers to identify the substance in the TSCA Inventory.[ii] In addition, production volume and other uses described in the SNUR may also be treated as confidential business information, creating a situation in which manufacturers or other product users may not know if their use of the substance will trigger regulation. These confidentiality protections may also impede the exchange of information relating to what specific forms of carbon nanotubes have bio-toxic properties.