7941

• UCREFRP Catalog Number: 7941
• Author: Johnson, W. W. and M. T. Finley
• Title: Editor
• USFW Year: Series
• USFW - Doc Type: 1980
• Copyright Material: NO

Preface
This Handbook is a compilation of results of toxicity tests on fish and aquatic in-
vertebrates conducted at the Columbia National Fisheries Research Laboratory in
1965-78. These studies, which were initiated under former Laboratory Director Oliver
B. Cope, include 1,587 acute toxicity tests on 271 chemicals against 28 species of fish
and 30 species of invertebrates. Many scientists and technicians have contributed sig-
nificantly in one way or another to the Handbook. However, the authors deserve the
major credit. Their work spanned several years and included countless evenings of
meticulous effort in reviewing and recalculating raw data, judging the quality of find-
ings, editing and compiling summary tables, and preparing the manuscript. Although
a number of acute toxicity tests were judged inadequate for inclusion in the Hand-
book, results of more intensive research were summarized and added for selected
chemicals.
The Handbook was produced as (1) a reference source for scientists and resource
managers and (2) a contribution to the data base essential to establishing water
quality criteria and to estimating potential environmental impacts of chemicals.
To better understand the relative value and use of acute toxicity data, one can group
problem chemical contaminants of the Nation into the following three categories: (1)
potential future contaminants accompanying development, such as new pesticides,
new industrial chemicals, new processes, energy extraction and processing, changing
land uses, and population changes; (2) contaminants that exist in aquatic habitats, but
are as yet unidentified or are poorly characterized; and (3) the general assemblage of
contaminants that have been known to exist in aquatic environments for some time.
Laboratory toxicological assessments, including acute toxicity measurements at an
early stage, are most appropriate for chemical contaminants in the first two cate-
gories. Toxicologists are well aware of the virtues and limitations inherent in the use of
the acute toxicity measure, yet there are probably few measurements that have been
as misunderstood in evaluating hazard or safety of a chemical to aquatic life as the
LC50 (concentration lethal to 50% of the test organisms during a specified exposure
period). Users of this Handbook, or users of any acute toxicity data, must bear in mind
that the LC50 measures only one biological response-death. Its main value is to
provide a relative starting point for evaluation, along with other measurements (e.g.,
water solubility of the chemical, its partition coefficient, and its degradation rate) of
the environmental hazard. In addition, the acute toxicity test provides a rapid, cost
efficient way to measure the relative toxicity of different forms and formulations of a
chemical in different types of water (acidic, basic, hard, cold, warm) and to organisms
representing different trophic levels.
In the early stages of evaluation, where acute measurements are most useful, the
LC50 has little more than academic value unless scientists or resource managers can
estimate the expected environmental concentration (EEC). At present, procedures for
making such estimates are far from precise, and range from "armchair" calculations
(based on estimates of volumes or flow rates of water, discharges, application rates,
etc.) to estimates based on physical-chemical properties of the chemical and actual
analyses of chemical residues present in the abiotic environment.
In general, comparisons of several LC50 values for fish and other aquatic organisms
with the EEC should be viewed as a "first cut" in assessing the potential threat of new
or little known chemical contaminants. When LC50's are three to four orders of magni-
tude above the EEC, the long-term effect of a chemical on aquatic life is likely to be
small. However, that generalization may not hold for a nontoxic material that phys-
ically disrupts, modifies, or destroys aquatic habitat or causes behavioral changes. As
the difference between LC50 and EEC declines, consideration must be given to more
definitive investigations of bioaccumulation and degradation rates and products, to
long-term toxicologic tests, or to integrated laboratory and field ecological studies.
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