is quite evident. The warmblooded animals undergo a short-term contact 

 with the polluted water which enters them in relatively small portions, 

 while the water is the permanent home of the aquatic organism. 



Does it mean that the criteria for toxicity and methods of estimation 

 of toxic effect of various chemical substances elaborated by general and 

 sanitary toxicology are not applicable to one of the classes of verte- 

 brates - fishes, and to aquatic invertebrates? Of course it does not. 

 The author (1973) has previously emphasized that toxicology of fish is a 

 part of comparative and general toxicology. In connection with this, many 

 ideas and methods may be used in solving the practical tasks of aquatic 

 toxicology associated with protection of waters from chemical pollution. 

 The last ten years of impetuous development of ichthyo-toxicological 

 investigations both in our country and abroad have yielded confirmation of 

 fruitfulness of this point of view. Today we can take the next step on 

 the way to consolidation of the efforts of medical man and biologists in 

 solution of the problem of "clean water". 



The unity of aims of both the sanitary-hygienic and fisheries per- 

 sonnel in establishment of standards for chemical substances discharged 

 into natural water (i.e., preservation of clean water in rivers and 

 reservoirs) conditions the necessity for creative analysis of the 

 principles of establishment of standards and elaboration of the universal 

 system of the MPC. This system must enable protection of water bodies 

 from ecological sanitary-hygienic and fisheries point of view. In 

 essence, from a biological approach. After all, the cleanliness of water 

 depends upon the biological processes of production and distruction; the 

 dynamic equilibrium which determines the high quality of "living" water. 



Within the foundation of the biological establishment of standards for 

 the MPC of chemical substances must lie the main elements of sanitary- 

 hygienic and fisheries principals established at the present time. This 

 includes the evaluation of the effect of chemical substances on organo- 

 leptic properties (taste and smell) of water and aquatic organisms, the 

 sanitary condition of the water-body (processes of mineralization of 

 organic pollution), the toxic action of the incoming substances upon 

 aquatic organisms of different levels of organization, and the effect upon 

 laboratory animals which are used by medical personnel for determining 

 sanitary-toxicological harmful ness. 



When expansion of the unit biological standard of the MPC is con- 

 sidered, the generally accepted methodical scheme of the sanitary-hygienic 

 setting establishment of standards of the MPC will not suffer any 

 essential change, since its validity is established. It is only necessary 

 to expand the genetic aspects of investigations, since many chemical 

 substances entering the waters with sewage are genetically active, i.e., 

 capable of bringing about both mutations and modifications in concentra- 

 tions that are significantly lower than those established for the hygienic 

 MPC (Rapoport, 1972). Genetic activity of toxicants (induction of genetic 

 mutations; aberration of chromosomes) is manifested at such a level that 

 is is impossible to evaluate these changes with the common physiological 

 and biochemical tests. The main object of investigations of the mutagenic 



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