||In its Spring 2009 Regulatory Agenda, the EPA announced that it may create a Toxic Substances Control Act (TSCA) section 4(a) test rule to determine the health effects of multiwall carbon nanotubes. Such a rule would require manufacturers of multiwall carbon nanotubes to perform health tests and submit the data to the EPA. To create such a rule, the EPA must demonstrate a possibility of exposure (although this can be inferred), and must also make statutory “data inadequacy” and “testing is necessary” findings. Section 4 test rules are created through a formal rulemaking process requiring public comment. The EPA believed that this rule might be needed to gather information so workers handling carbon nanotubes will be able to protect their health. Subsequent to this notice, the EPA proposed significant new use rules (SNURs) under section 5(a)(2) of the TSCA for carbon nanotubes (see report ID 415).