Don't Be Half-Safe — The Current
Revolution in Bioassay Techniques
JOHN CAIRNS, JR., Professor
Department of Zoology
University of Kansas
Lawrence, Kansas
INTRODUCTION
In 1945 Hart, Doudoroff, and Greenbank(l) described a procedure forbioas-
says of industrial wastes which used fish as test organisms, which was subsequently
recommended as a standard test by Doudoroff, et al (2). These methods and their
various modifications now have been very widely used by regulatory agencies, industries, and other groups for assessing the toxicity of various industrial wastes and
other potentially toxic materials. The original method, although considered provisional by its authors, was so practical and useful that it continues to be used essentially in its original form to this day. Like BOD, it has many weaknessess,
drawbacks, and sources of error but is widely used because of its simplicity.
Despite increased use of bioassay techniques it is quite likely that many industries in the United States have no idea what specific effects their particular effluent has upon aquatic organisms. In short, the absence of any evidence to
the contrary, it seems that many industries still rely on indirect evidence (literature, state standards, etc.) rather than the direct evidence provided by a test involving their particular effluent with at least one representative aquatic organism
in a water comparable to the receiving water. Undoubtedly, one of the principal
reasons for this over-reliance upon indirect information is the general lack of state
and federal laws requiring specific evidence of the degree of toxicity of a particular effluent mixture to aquatic organisms. There seems to be little doubt, however, that this situation should not persist for many more years, considering the
many problems affecting out water supply.
REVOLUTION IN METHODOLOGY
During the twenty years since the basic bioassay method was developed by
Hart, Doudoroff and Greenbank, a large amount of research information has been
accumulating in aquatic toxicology and related fields. The development of new
techniques for assessing toxic effects has finally increased to the point where it
may be called a revolution. The impact of this revolution upon methodology will
probably center on two points. First, acute or short term dose-response tests (i. e.,
96 hrs or less) are no longer sufficient! Second, evidence of nonlethality is also no
longer sufficient; one must show that there are no harmful effects other than death!
The first of these points, the acute versus the chronic test, really needs little
explanation since the argument is more philosophical than scientific. We would
not think of permitting a drug or any other substance prepared for human consumption to be marketed with a mere 24, 48 or 96 hour screening test. At the very
minimum we would expect tests extending over many months, and we would not
consider tests involving several generations of rats or other test organisms to be
excessive. We believe this because we rightly place a very high value upon the
the lives of our fellow human beings. The duration of the tests is, in a way, a
measure of the value that we place upon our own safety and that of our fellow
man. It is then evident that the length of a bioassay test is more likely to be influenced by our regard for the organism which the testing is designed^ to protect
than by the testing techniques themselves.   Thus, as our recognition of the value
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