For a bioconcentration factor (BCF) to be calculated from a site-specific study, the field data must show that the chemical’s concentration in water remained constant over the range of the organism’s inhabitation and for a time period not less than 4 weeks. Another condition is that the chemical’s bioavailability was not affected by its removal from the solution through competing mechanisms. The third and final condition is that the chemical’s concentration which the test organism was exposed to must be below the lowest that would cause an adverse effect on the organism.

For BCFs calculated from a laboratory test, five conditions should be met. First, the BCF should be calculated from the chemical’s concentrations measured in a test solution. Second, the laboratory test must be either of sufficient duration to reach steady-state or, alternatively, lasting 4 weeks or more. Third, like for field data, the chemical’s concentration which the test organism was exposed to must be below the lowest that would cause an adverse effect on the organism. Fourth, the BCF should be calculated on a wet tissue weight basis. Finally, the (geometric) mean should be used if more than one BCF for the same species is available.

In many Western and European countries, it is recommended that the laboratory studies be conducted using a test method similar to the one stated in the Organization for Economic Cooperation and Development (OECD, 2002) Test Guidelines 305. In certain aspects, the OECD guidance is similar to that provided by U.S. EPA (Code of Federal Regulations, 2003). Nonetheless, most regulatory authorities agree that field studies generally provide more appropriate or more accurate BCF estimates for a bioaccumulation factor.