HAZARDOUS SUBSTANCES: A THREAT TO AQUATIC RESOURCES 



J. Larry Ludke and Richard A. Schoettger 



Columbia National Fisheries Research Laboratory 



U.S. Fish and Wildlife Service 



Columbia, Missouri 



The age of chemistry has introduced a multitude of chemical contaminants, 

 many of which are incompatible with man's environment and threaten the wel- 

 fare of living resources everywhere. Identification of some of the insidious 

 effects that result from chronic exposure of biota to these chemicals is only 

 beginning. Considerable efforts are being made to evaluate the effects of 

 chemicals that are already being used and disposed of. However, the evalua- 

 tion of future hazards to fish and wildlife resources must be improved. Such 

 an effort necessarily requires a multidisciplinary approach that emphasizes 

 the anticipation of contaminant threats of the future. Researchers, resource 

 managers, and other decisionmakers in industry and government will have to 

 participate closely in sharing information and assessing the impacts of con- 

 taminants on living resources. Only in this way can the present reactionary 

 posture in addressing the pollution problems of the future be avoided. 



More than 87,000 chemicals now produced in the United States are possible 

 environmental contaminants. The U.S. Environmental Protection Agency (EPA) 

 has listed 129 toxic substances for immediate hazard assessment related to 

 production, distribution, use, disposal, and persistence in the environment. 

 Data on toxicity, environmental fate, degradation, ecological impact, and hu- 

 man health must be assimilated for a full and meaningful hazard assessment of 

 many of these toxic substances. Many more chemicals await intensive study to 

 determine their potential impact in the environment. The chemical complexity 

 of hazardous substances ranges from simple discrete compounds such as DDT to 

 highly complex multicomponent mixtures. The polychlorinated biphenyls (PCB's) 

 and the insecticide toxaphene each include more than 100 isomers of varying 

 degrees of toxicity and persistence (Zell et al. 1978, Jansson et al. 1979). 

 Oil and coal, which contaminate the environment by spills, natural seepage, 

 combustion, and careless disposal, are even more complex. They contain numer- 

 ous organic compounds, metals, and organometall ic complexes. The complexity 

 of such contaminants is staggering, and is further complicated by the differ- 

 ences in the chemical composition of coal and oil from one location to another. 



SETTING RESOURCE PRIORITIES 



The potential for study and hazard assessment of this multitude of new- 

 generation contaminants is overwhelming. Many contaminants cannot be analyz- 

 ed or identified in biological matrices by using existing technology. It is 

 difficult to formulate realistic hazard assessments without knowing a chemi- 

 cal's environmental concentrations and biological availability. From 



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