AbstractOver the past 20 years there has been a concerted effort to define and limit the impacts of anthropogenic contaminants in aquatic environments. There are essentially two philosophies that can be employed to regulate and to assess the effects of toxic chemicals in these systems. The first is the water quality objectives research. Under this protocol, laboratory research is used to set an objective, the concentration of a substance or condition that is considered to have no effect on the organisms in an aquatic environment based on a review of the pertinent research. The second approach, environmental health assessment, uses the in situ responses of free‐living organisms in contaminated environments to determine the overall impacts of the environment on those organisms. In this review paper we will attempt to compare and contrast the advantages and disadvantages of the two approaches, and to outline a system whereby they can be used together to enhance our degree of confidence in legislation directed at reducing contaminant impacts. ©by John Wiley&Sons, I