28-Day (Subacute) Inhalation Toxicity Study (OECD TG 412)

TG 412 is an OECD validated test designed to fully characterize test chemical toxicity by the inhalation route following repeated exposure for 28 days, and to provide data for quantitative inhalation risk assessments. Groups of at least five male and five female rodents are exposed six hours per day for 28 days to a) the test chemical at three or more concentration levels, b) filtered air (negative control), and/or c) the vehicle (vehicle control). Animals are generally exposed five days per week but exposure for seven days per week is also allowed. Males and females are always tested, but they may be exposed at different concentration levels if it is known that one sex is more susceptible to a given test chemical. This guideline allows the study director the flexibility to include satellite (reversibility) groups, bronchoalveolar lavage (BAL), lung burden (LB) for particles, neurologic tests, and additional clinical pathology and histopathological evaluations in order to better characterize the toxicity of a test chemical.