Chemicals may affect the ecological quality of environmental compartments such as surface waters. In order to assess the environmental risks, the effects of these chemicals are tested in laboratories with specific organisms exposed to a range of concentrations. Information generated with such tests is often stored in large databases. When environmental risk is assessed, such databases are consulted before new tests are performed. This is to prevent unnecessary experiments that cost animals, time and money. Of course, existing data should be of sufficient quality for the intended purpose, certain, accurate, reliable and relevant. In my research, approaches to judge and apply these aspects are evaluated and improvements suggested.