Hazardous substances, CERCLA, and nanoparticles - can the three be reconciled?

Toxicology research in the nanotechnology area has focused primarily on human inhalation, ingestion or dermal exposure. Less research has been published on the impact to ecological systems resulting from a release of nanomaterials. Environmental laws such as CERCLA ("Superfund") address the release of "hazardous substances" by obligating the party releasing the substance to (a) report the release and (b) investigate the nature and extent of the release and to then remediate it to some objective cleanup standard. Applying this regime to the release of nanomaterials, however, is complicated. First, is the nanomaterial a hazardous waste, toxic substance, or hazardous substance as defined under the environmental laws? A compound that may be defined as hazardous or toxic could have properties at the nano level that are distinctly non-hazardous. Second, what constitutes a release of a nanoparticle that would require reporting under applicable environmental laws? Typically, release reporting is based upon the weight of the hazardous substance that is released, but for nanomaterials a weight threshold might be meaningless. Third, how do you sample nanoparticles in the field and analyze them using existing instrumentation? There are few approved tests for nanomaterials. Fourth, how do you determine an objective risk-based cleanup standard for the thousands of possible nanomaterials?