ABSTRACT
This chapter focuses on carbon nanotubes, other nano-objects are also used in commerce. Under the Toxic Substances Control Act, US Environmental Protection Agency is currently required to assess and regulate risks to human health and the environment before a new chemical substance is introduced into commerce. Toxicity testing for inhalation exposures is not a trivial exercise, as there are many variables to control. Using the mechanism of action of an agent is the future of toxicology and is crucial to understanding how the physicochemical characteristics of a nano-object are linked to toxicity. Acute toxicity tests are tests where doses are given in a single exposure, often high enough to produce a short onset of adverse effects. An aggregate is a particle comprising strongly bonded or fused particles where the resulting external surface area may be significantly smaller than the sum of calculated surface areas of the individual components.
