The Organisation for Economic Co-operation and Development (OECD) has published Guidance for waiving mammalian acute toxicity tests for systemic toxicity as well as those assessing local irritation, corrosion, or sensitisation. Criteria include consideration of the physicochemical properties of the test substance. For example, in the case of acute inhalation toxicity, if the substance demonstrates low volatility, is not aerosolized or otherwise made inhalable as a gas or vapour under conditions of use, storage, handling, or transport then the test can be waived. The Guidance also covers the use of existing data from other similar substances for read-across, and it can be viewed on the OECD website here.