This part of ISO 14592 specifies a test method for evaluating the biodegradability of organic test compounds by aerobic microorganisms by means of a shake-flask batch test. It is applicable to natural surface water, free from coarse particles to simulate a pelagic environment (“pelagic test”) or to surface water with suspended sediments added to obtain a level of 0,1 g/l to 1 g/l dry mass to simulate a water body with suspended sediment (“suspended sediment test”). This part of ISO 14592 is applicable to organic test compounds present in lower concentrations (normally below 100 μg/l) than those of natural carbon substrates also present in the system. Under these conditions, the test compounds serve as a secondary substrate and the kinetics for biodegradation would be expected to be first order (“non-growth” kinetics). This test method is not recommended for use as proof of ultimate biodegradation which is better assessed using other standardized tests (see ISO/TR 15462). It is also not well suited to studies on metabolite formation and accumulation which require higher test concentrations.