User Guide to Thresholds and Classification - Environmental ...

136User Guide for Thresholds and Classifications10. Acute Toxicity – Subclass 6.110.1. General considerations10.1.1. Acute toxicityAcute toxicity refers to those adverse effects occurring following the oral or dermal administration of a singledose of a substance, or multiple doses given within 24 hours, or an inhalation exposure of four hours.See section 9.6 in chapter 9 for definitions of the key terms used in this chapter.10.1.2. Weight of evidenceThe best quality data should be used as the fundamental basis for classification. Preferably, classificationshould be based on primary data sources. It is essential that test conditions be clearly and completelyarticulated.Data from internationally harmonised test methods are preferred for classification under this subclass.Preferably, data should preferably be derived using Organisation for Economic Co-operation andDevelopment (OECD) Test Guidelines or equivalent according to the principles of Good Laboratory Practice(GLP). Where such data are not available classification should be based on the best available data using aweight-of-evidence approach.See section 1.3 in chapter 1 above for information about assessing data quality.See Appendix 10A below for a detailed list of acceptable test methods for acute toxicity.10.2. Acute toxicity hazard and classification criteria10.2.1. Acute toxicity hazard and threshold criteriaSchedule 4 to the Hazardous Substances (Minimum Degrees of Hazard) Regulations 2001 states:2 Minimum degrees of hazard(1) A substance with toxic properties is not hazardous for the purposes of the Act unless—(a) data for the substance indicates a LD50 of 5000 milligrams or less of the substance perkilogram of bodyweight as a result of acute exposure of animals to the substance by oralor dermal routes; or(b) data for the substance indicates any mortality, as a result of acute exposure of animalsby—(i) oral or dermal routes to 2000 milligrams or less of the substance per kilogram ofbodyweight; or(ii) the inhalation route to—(A) 5000 parts or less of the substance per million in air, if the substance is a gas;orJanuary 2012 EPA0109