Estimating the PTB-profile

The overview reported here is meant to represent an inventory of 'simple' methods to estimate missing data on Persistence (P), Toxicity (T) and Bioaccumulative potential (B) of substances. Estimation models offer the quickest and cheapest ways of doing this, and are relatively more reliable than expert judgement or default values. Prior to estimating the PTB properties, a distribution profile, i.e. the distribution of the substance over the three major environmental compartments of air, soil and water, had to be determined. The information required for substances in estimating the PTB properties varies from a SMILES notation to detailed quantum-mechanical data. Flowcharts are provided in the overview to guide the reader through the required steps for determining the PTB properties. The PTB properties and PTB criteria can be used for simplified hazard identification for human health and the environment. A substance-specific PTB profile can thus be derived to include the PTB properties. Comparing PTB properties to 'cut-off' values for substances in relation to a particular policy aim can result in categorization of substances into a PTB class. The establishment of 'cut-off' values is a policy choice still under discussion, as is the use of PTB criteria for policy purposes, both are therefore outside the scope of the report.