9637

• UCREFRP Catalog Number: 9637
• Author: American Society For Testing And Materials.
• Title: Standard Practice For Conducting Acute Toxicity Tests With Fishes, Microinvertebrates, And Amphibians.
• USFW Year: 1980.
• USFW - Doc Type: Philadelphia, PA.
• Copyright Material: YES

ride or sulfate salts of organic amines, sodium
or potassium salts of phenols or organic acids,
and chloride or nitrate (rather than carbonate
or hydroxide) salts of metals. If solvents other
than water are necessary, the amount used must
be kept to a minimum. Because of their low
toxicity to aquatic animals (17), low volatility,
and high ability to dissolve many organic com-
pounds, dimethylformamide and triethylene
glycol are often good organic solvents for pre-
paring stock solutions, but methanol, acetone,
and ethanol may also be used. The concentra-
tion of solvent in any test solution must not
exceed 0.5 mL/L. If a solvent is used, it may be
desirable to conduct simultaneous tests, either
with two chemically unrelated solvents or with
two different concentrations ofthe same solvent
to obtain information concerning the possible
effect of solvent on results of the test (11.1.2).
9.2 Concentrations Tested~ The concentra-
tions of toxicant used in a test to determine an
LC50 or EC50 must meet the requirements
of 12.2. If necessary, concentrations above sol-
ubility in water should be used because orga-
nisms are sometimes exposed to concentrations
above solubility and because solubility is often
not well known. The use of concentrations that
are more than ten times greater than solubility
are probably not worthwhile. An estimate of
the LC50 or EC50 might be obtained from tests
on the same or a similar material with the same
or a different species. However, in most cases
a range-fmding test is desirable. Generally in
such a test, groups of five organisms are ex-
posed to three to five widely spaced toxicant
concentrations and a control for 24 to 96 h.
The greater the similarity between the range-
fmding test and the actual test, the more useful
the range-fmding test will be.

10. Test Organisms

10.1 Species~ Whenever possible, tests
should be conducted with species selected from
those listed in Table 6. These species were
selected on the basis of availability, commer-
cial, recreational, and ecological importance,
past use, and ease of handling in the laboratory.
Their use is encouraged to promote uniformity
for comparability of results and so that much
information becomes available about a few
species, rather than a little information about
many species. If a listed species is unavailable,

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organisms from a listed genus should be used.
A specific strain should be used only when that
strain is of special concern. Rare or endangered
species must not be used. The scientific name
of the species used must be verified.
10.2 Source~All organisms in a test should
be from the same source, since organisms of the
same species from different sources may pro-
duce different results in an acute toxicity test.
Laboratory cultures of test organisms usually
can provide organisms whose history, age, and
quality are known and similar at all times of
the year in all laboratories. Freshwater amphi-
pods, caddisflies, daphnids, burrowing may-
flies, midge larvae, mosquito larvae, and
saltwater polychaetes should be reared in the
testing facility from laboratory cultures (18).
Daphnids from cultures in which ephippia are
being produced should not be used. Small fish
such as fathead minnows can also be raised in
laboratory cultures. Usual sources of other
freshwater fish are private, state, and federal
hatcheries. Whenever trout are to be used, they
should be obtained from a hatchery that has
been certified disease-free (free of infectious
pancreatic necrosis, furunculosis, kidney dis-
ease, and whirling disease) if possible. Other
species are usually obtained directly from wild
populations in relatively unpolluted areas. Im-
porting and collecting permits may be required
by local and state agencies. Organisms captured
by use of electroshocking, chemical treatment,
and gill nets should not be used.
10.3 Size~All organisms in a test should be
approximately the same size and age.
10.3.1 Fish~ Use of fish weighing between
0.5 and 5.0 g each is usually desirable. Unless
there is a specific reason for doing so, very
young (not actively feeding), sexually mature,
spawning, or recently spent fish should not be
used. Tests can be conducted with newly
hatched fish, which are sometimes more sensi-
tive than older stages, and embryos if appro-
priate precautions are taken. In any single test,
all fish should be from the same year class, and
the standard length (tip of snout to end of
caudal peduncle) of the longest fish should be
no more than twice that of the shortest fish.
10.3.2 Invertebrates~Except for shell depo-
sition tests with bivalve molluscs and tests with
copepods, immature organisms should be used
whenever possible, because they are often more

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