Cellular and subcellular measures of exposure (biomarkers) and effects (bioindica-
tors) continue to be developed.However, application of biomarkers in assessing ecological risk remains infrequent
and of questionable utility.The primary
challenges in using biomarkers/bioindicators to assess risk include the difficulties in

(1) developing stressor-specific, quantitative dose-response functions and (2) project-
ing higher-order ecological effects from cellular or subcellular bioindicators.