(Includes n=4 mice/group @ 3 concentrations of Test Article plus Vehicle Control group; Historical Positive Control) Pooled Nodes from each group. Modified OECD TG429 does not include irritation/systemic toxicity Pre-Screen test.

*This is intended only as the most basic screening assay; dermal (ear) irritation will be assessed during the test; there will not be an irritation pre-screen unless requested on Protocol. (Not recommended for new chemicals or mixtures without previous dermal irritation and sensitization data)

**OPPTS 870.2600 and OECD TG429 guidelines specify that "an irritation pre-study should be performed under identical conditions as the main test in order to determine the maximum (irritation threshold) test concentration." Basic Range finding Pre-Screen is 6 mice at 3 concentrations. See below for a more comprehensive quantitative range-finder test for suspected or known irritants.

Quantitative Range-Finder: If no mouse ear irritation data is available or provided, a quantitative range finder using 12 mice with n=2 at 6 concentrations (100%, 50%, 25%, 10%, 5%, 2.5%) should be performed first, these will allow proper choice of test concentrations for the main LLNA study. If the Test Article is irritating, a second range-finder at lower doses (1%, 0.5%, 0.25%, 0.1%, 0.05%, etc.) may be necessary.