Various types of bioassays have been carried on in the United States for many years. the teens Shelford (1917) initiated studies to determine the attracting or repelling perties of various substances, such as gashouse wastes, for fishes. He developed cial methods and equipment for these studies. During the twenties and thirties, use of bioassays increased and considerable work was devoted to refining techhniques and checking water flow rates and the volume of water needed. However, there was great diversity in the bioassay methods used; the various workers d different species, different periods of exposure, wastes of different quality, d there was no uniformity in reporting of results. In fact, very often the methods used were not described so that the data obtained could not be compared with those of other workers. Examination of the results indicated that there was a wide inference in the reported toxicity levels for the same materials, even when tested h the same species. It was recognized in the forties that some standardization bioassay methods was needed if they were to be used to indicate the toxicity various wastes and other materials to aquatic organisms and provide comfarable data. Hart, Doudoroff & Greenbank (1945) reviewed the various bioassay methods in use and suggested approaches to their use for toxicity determinations and pointed out the need for completeness and uniformity in the reporting of ults. They also suggested an ‘application factor’ which could be applied to uts of short-term acute bioassay tests to estimate safe levels under conditions long-term exposure in the environment. Throughout the forties, the need for a standard bioassay method and uniform recording and reporting of results became re evident. This need for standardization was recognized in 1949 by the Biology Section of fie Environmental Health Center, U. S. Public Health Service, at Cincinnati, Ohio. is Center later became the Robert A. Taft Sanitary Engineering Center of the IS. Public Health Service. In 1949, a Sub-committee of the Research Committee the Water Pollution Control Federation was formed for this purpose. Dr Dou roff of the Aquatic Biology Section of the R. A. Taft Center was made Chairman, and an able committee was formed which drew up proposed standard methods f bioassays. The report of this Committee entitled ‘Bioassay methods for the evaluation of the acute toxicity of industrial wastes to fish’ was published in the
Journal of sewage and industrial wastes
in 1951. These methods were used routine and gradually improved upon by the Aquatic Biology Section of the Robert Taft Sanitary Engineering Center. Modifications of these suggested procedure were prepared by the Toxicity Subcommittee of the Research Committee of the Water Pollution Control Federation under the direction of the author and were published in the 11th Edition of
Standard methods for the analysis of water and wastewater
. These methods were used widely and were accepted as standard methods for short-term acute bioassays using fish. The need to devise method employing other organisms was recognized very early and some efforts were made in this direction. The author encouraged those working with other organisms write up their bioassay methods for consideration by the Committee for inclusio in the 13th edition. However, upon examination of several methods it was decide that they should be more thoroughly tested before being included in
Standard methods
. Methods for long-term, continuous renewal bioassays with fish were described and approved by the Committee and are being included in the 13t edition of
Standard methods
. This edition is to become available late in 1970.
Problems of Bacteriological Pollution in Water Wells in Wadi Hadramout Water Project
