User Guide to Thresholds and Classification - Environmental ...

150User Guide for Thresholds and Classifications1.0 < Category 4 5.0 1.5Category 5Notes: Gases concentration are expressed in parts per million by volume (ppmV); LD 50 = median lethal dose;median lethal concentration = LC 50; mg/kg bw = milligrams per kilogram of bodyweight; mg/L = milligrams per litre.a. Criteria for 6.1E are intended to enable the identification of substances that are of relatively low acute toxicityhazard but that under certain circumstances may present a danger to vulnerable populations. Thesesubstances are anticipated to have an oral or dermal LD 50 in the range of 2,000 – 5,000 mg/kg bw andequivalent doses for inhalation exposure. Recognising the need to protect animal welfare, testing in animals incategory 5 ranges is discouraged and should be considered only when there is a strong likelihood that theresults of such a test would have a direct relevance for protecting human health.b. The converted LD 50 and LC 50 values are designed to be used in the calculation of the acute toxicity estimatefor classifying a mixture based on its components, and do not represent test results. The values areconservatively set at the lower end of the range of categories 6.1A and 6.1B, and at a point approximatelyone-tenth from the lower end of the range for categories 6.1C–6.1E.ReferencesUnited Nations 2007. The Globally Harmonized System of Classification and Labelling of Chemicals (GHS),2nd revised edition. United Nations, Geneva.January 2012 EPA0109