Division 4.1.2.3 F1

F2The criteria for classification of a substance in Acute 1 are defined on the basis of acute aquatic toxicity data only (EC50 or LC 50). The criteria for classification of a substance into Chronic 1 to 3 follow a tiered approach where the first step is to see if available information on chronic toxicity merits long-term (chronic) hazard classification. In absence of adequate chronic toxicity data, the subsequent step is to combine two types of information, i.e. acute aquatic toxicity data and environmental fate data (degradability and bioaccumulation data) (see Figure 4.1.1).