ABSTRACT
Ecotoxicologists ultimately endeavor to understand the attributes of toxicants in the real world. Although controlled studies can contribute to that understanding, they are often plagued by an inability to translate laboratory results to real ecosystems: the so-called lab-to-field dilemma (Landis and Yu, 1995). The labto-field dilemma is of particular concern for bioaccumulative toxicants because standardized aquatic bioassay testing rarely includes a dietary pathway, and dietary exposure of fish and wildlife to bioaccumulative toxicants is usually the primary risk factor. That critical flaw was appropriately recognized by the U.S. Environmental Protection Agency (EPA) when the freshwater chronic criterion for selenium was established at 5 micrograms per liter (jmg/L) in 1987. EPA established the 5 julg/L criterion based largely on a single well-documented episode of selenium poisoning in nature rather than on a larger accumulation of data from bioassay toxicity testing (USEPA, 1987). Although that choice was clearly prudent, a national water quality criterion based largely on one real-world case study is an easy target for criticism. A single study does not provide sufficient basis for assessing a criterion’s applicability across a variety of aquatic ecosystems and site-specific environmental conditions.
