Page 680 - The Toxicology of Fishes

660 The Toxicology of Fishes

a reality. Laboratory and field (in situ cage studies) investigations were conducted with lead to assess
the impact of mine tailing effluents (Carpenter, 1925, 1930). Carpenter was also the first to note the
effects of hardness on the toxicities of divalent metals. Belding (1927) and Ellis (1937) described the
conditions (i.e., test variables) that affected fish as test organisms and dilution water quality. Ellis also
established one of the first hazard ranking systems based on fish responses to municipal and industrial
effluents. Prior to World War II, most toxicity studies with fish (e.g., goldfish, minnows, salmonids) were
conducted with regard to industrial wastes and metals, and some early attempts were made to develop
and describe standard acute toxicity tests with fish. It was not until after World War II, however, that
efforts were directed toward standardizing techniques for fish acute toxicity tests (Hart et al., 1945). It
was the era of the “pickle-jar bioassays,” in which acute tests with single species were conducted in
5-gallon pickle jars. Scientists from Canada, the United States, and England demonstrated the utility of
exposing fish to industrial wastes and other chemicals for predicting the potential toxicity to freshwater
systems. Fish tests were also used to assess the effects of environmental factors (e.g., changes in
temperature, dissolved oxygen) on toxic responses. Work by the earlier groups of scientists established
acute toxicity tests as the workhorse for studying and monitoring pollution effects (Buikema et al., 1982),
a position it still retains. The fish acute toxicity test was the basis for the first aquatic toxicity protocol
of the American Society for Testing and Materials (ASTM), and, in the 1960s, the American Public
Health Association included fish toxicity test procedures in its well-established Standard Methods for
the Examination of Water and Wastewater (APHA et al., 1960).
Interest and concerns about chronic, low-level exposures occurred during the 1960s as a result of the
distribution of organochlorine compounds. This stimulated the development of flow-through techniques for
use in studies on long-term exposures of aquatic organisms to chemicals. Experiments were also initiated
in the 1960s that included exposures during early life stages and full life cycles, as well as the measurement
of sublethal endpoints. The 1970s also saw acute fish toxicity being used as an acceptable parameter for
protocols used in regulatory testing. In the 1980s and 1990s, there was a greater appreciation for under-
standing mechanisms of toxic action (or modes of action; see Chapter 5) of chemicals and suborganismal
levels of assessment (see Chapters 7 to 13). Without knowledge of the sites of action (or biochemical
lesions), it is possible that potentially important physiological effects may be undetected and overlooked.
Greater use of different fish toxicity techniques were built into regulatory guidelines, regulations, and codes
of practice throughout the world. For a good summary of the history of acute toxicity testing with fish, see
Hunn (1989). Also, for a summary of fish toxicity testing techniques, see Sprague (1969, 1970, 1971).
It is important to study other aquatic organisms and different levels of organization in aquatic systems
because of the roles different organisms play in food chains; however, this chapter focuses on laboratory
fish toxicity tests. Toxicity tests are traditionally conducted to assess or predict the biological effects of
chemicals (e.g., industrial, pesticides, PAHs) and determine the relative toxicity of such substances. Just
as there are many different biological levels of organization at which a chemical can exert effects, a variety
of toxicity test methods are available to investigate the type and severity of such effects. General concepts
and test methods for fish are presented in this chapter, although they can be applied to other species.
Fish toxicity tests can be conducted in the laboratory or in the field, and the individual organism is
the basic unit of study. Laboratory tests with fish have been standardized with established protocols and
greater control over environmental variables then field tests (see Chapters 19 to 25). Few standardized
protocols are available for field tests with fish and other aquatic organisms. Historically, most fish tests
have been done in the laboratory, and most hazard and risk evaluations used in risk management decisions
are made on the basis of laboratory results. Field validation of laboratory-derived toxicity tests, however,
is often considered a necessary tool in the ecological risk evaluation process (see Chapter 18).

Objectives and Limitations

Toxicity tests may be used to meet one or more of the following objectives:
• To develop data to better understand biological effects and exposure
• To generate data to support decisions for risk assessment and risk management