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Advances in technology have given scientists a number of alternatives to using animals in research. Use of tissue cultures and computer models are examples of alternatives that may, in some research studies, replace the need for animals.
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Replacement
is one of the triad of alternatives to animal research first recognized by
William Russell and Rex Burch in their 1959 book "The Principles of Humane
Experimental Technique." They believed that researchers have a duty to
replace animal tests with other kinds of tests whenever possible.
An example
of a common animal test that has been replaced with new technology is the
so-called "rabbit test," an early form of pregnancy test. In the
early 1920s, scientists discovered that a woman produces a hormone, called
human chorionic gonadotropin (hCG), soon after becoming pregnant. They also
found that rabbits injected with this hormone displayed distinct changes in
their ovaries, and thus the "rabbit test" was born. In the early
tests, the rabbits were euthanized so their ovaries could be examined; later
refinements to the test enabled the rabbits' lives to be spared.
While
modern pregnancy tests are still based on measuring hCG, it is now done
directly, using either the woman's blood or urine. A simple biochemical test
has eliminated the need for animal testing.
Russell and
Burch distinguished between relative replacement - the use of animals to
provide cells, tissue or organs for in vitro, or test tube studies - and
absolute replacement in which animals are not needed at all. For example,
studies using tissue cultures still typically require a biopsy or the
euthanization of an animal to produce the tissue material. However, a single animal
can provide tissue for a number of cultures.
In some
cases, lower organisms, such as invertebrates, plants and microorganisms, can
substitute for research using vertebrates. In other cases, in silico
testing - the use of computer models or simulations to replace physical
experiments - can potentially replace some forms of animal research.
Replacement
sometimes can occur simply from increased access to information. To ensure that
research studies do not duplicate previous work, the CNPRC and UC Davis require
that researchers proposing to do a study involving animals conduct a thorough
literature search before they will approve the project.
Sometimes
partial replacement is possible. For example, a combination of alternative
methods can be used to pre-screen substances for toxicity. If preliminary tests
show the substance is toxic, it need not be tested on an animal. Only a
negative result would necessitate additional testing using animals.
However, it is extremely difficult to replace all animal
research with alternative methods. To solve complex problems in medicine,
researchers need access to all the tools of modern science, including the use
of animal models when in vitro and in silico methods will not
suffice. Since many types of biomedical research cannot be conducted on humans
for ethical, moral and legal reasons, animals are irreplaceable for
understanding disease processes and for testing new drugs, surgical methods and
other treatments that benefit not just humans but other animals as well.
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