247 



Some of the factors affecting the survival of pathogenic organisms 

 are — 



(1) Environmental conditions such as salinity, temperature, 

 amount o'f sunlight, and degree of dilution. 



(2) Biological agents antagonistic to the survival of the waste- 

 borne organisms. 



(3) Bacteriophages or viruses. 



(4) Protozoan and other lower animals which consume patho- 

 gens for survival. 



(5) Sedimentation and adsorption of pathogens with and 

 by particulate matter in the receiving water, 



(6) The amount of nutrient material available to support or 

 stimulate multiplication of the organisms. 



The presence of the colif orm organisms, especially the fecal colif orm, 

 is an index to the degree of public health hazard. The two main avenues 

 of exposure for humans in the estaurine environment are through 

 body contact during recreation and through ingestion of contaminated 

 food harvested from the estuary. In the former, the problem becomes 

 one of balancing reasonable safeguards for public health and well- 

 being against undue restrictions on the availability of waters for con- 

 tact recreation. In estuarine recreation water, this problem is compli- 

 cated by the lack of definitive epidemiological studies correlating the 

 incidence of waterbome disease with degrees of bacterial pollution. 

 To develop rational bacterial standards for contact recreation, the 

 most promising approach appears to be through intensive monitoring 

 of indicator organisms coupled with salinity studies. 



Shellfish contamination presents another problem in that the major 

 concern is the ingestion and harboring of pathogenic enterovirus and 

 bacteria by the organism. These viruses can then be passed on to a 

 human host, especially if the shellfish are eaten raw. The relationship 

 between the densities of colif orm indicator organisms and the presence 

 of enteroviruses is still ill-defined and needs further definitive investi- 

 gation to assure the adoption of rational public health protecting cri- 

 teria. At present shellfish closures are based on very stringent colif orm 

 bacteria concentration standards designed to provide a safety factor 

 to insure public health. 



TOXIC MATERIALS 



Among the waste products frequently introduced into the estuarine 

 environment are some directly toxic to marine organisms. Toxic mate- 

 rials may exhibit a short catastrophic impact or a more subtle long- 

 term interference with growth and reproduction processes. The end 

 result is the creation of a biological desert in which no organism can 

 survive. 



The short-term catastrophic type of toxicity usually results from an 

 accidental spill or slug discharge of materials into the water. The 

 impact is immediate and the results are dramatic. 



The long-term type of toxicity is manifested through the gradual 

 destruction of the natural biota. The effects of sublethal concentra- 

 tions of toxic mateirials are amplified through biological magnifica- 

 tion. Many animals, especially shellfish, can remove these materials 

 from the environment and store them in their tissues. This magnifica- 



42-847 O— 70 17 



