This revised Test Guideline 412 (TG 412) has been designed to fully characterize
test article toxicity
by the inhalation route following repeated exposure for a limited period of time (28 days), and to provide data for quantitative inhalation risk assessments.
Groups of at least 5 male and 5 female rodents are exposed 6 hours per day for 28 days to a) the test article at three or more concentration levels, b) filtered air (negative control), and/or c) the vehicle (vehicle control). Animals are generally exposed 5 days per week but exposure for 7 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 article. This guideline allows the study director the flexibility to
include satellite (reversibility) groups, bronchoalveolar lavage (BAL), neurologic tests, and additional
clinical pathology and histopathological evaluations in order to better characterize the toxicity of a test