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Better Science
Limitations
of Animal Tests
LD50 Test
The traditional LD50 (lethal dose 50%) test
forces animals to ingest chemicals to determine the approximate dose
that results in the death of half the test animals. The animals are
often force fed by a tube inserted down the esophagus into the stomach.
This often causes severe discomfort, and in many cases, extreme and
unrelenting pain.
This crude method, using up to 100 animals per test, was introduced
in 1927 by British pharmacologist J. W. Trevan. Since then, millions
of animals have died excruciating deaths. The Interagency Research
Animal Committee admits, “The LD50 tests have become controversial
among toxicologists, animal welfare organizations, legislators and
the public primarily due to the ethics of using a large number of
animals and evaluating only mortality.” (National
Institutes of Health Web site)
Recently, the traditional LD50 test has come under scrutiny for its
inhumane and unreliable results. In fact, the Consumer Products Safety
Commission, the Department of Transportation, and the Environmental
Protection Agency discourage the use of the LD50 test.The Food and
Drug Administration does not require its use and the National Toxicology
Program does not use this test. These agencies and programs recommend
alternative testing such as existing animal data, prior human experience,
and/or the Limit test (a test that uses 10 animals in acute toxicity).
The late Dr. Björn Ekwall of the Cytotoxicology Laboratory in Sweden
developed a replacement for the LD50 test that measured toxicity at
a precision rate of 77% compared to the LD50 rate of 60%-65%. This
test, which is more accurate than the animal models, is cruelty-free
in that it uses donated human tissue, rather than animals.
Dr. Ekwall stated that, “it would be irresponsible [for companies]
not to use these…[alternative] tests to provide extra information
for [the] protection of consumers.” (“There Is A Better Way; MEIC
Finalizes a Replacement Method for the LD50 Test.” Boston, MA: New
England Anti-Vivisection Society, 1999)
The Draize Test
In 1944, John H. Draize, a scientist with the
U.S. Food and Drug Administration, developed an eye irritancy test
in rabbits using an irritation scoring system subsequently called
the Draize test.
In this test, conscious rabbits are immobilized while chemicals are
put directly into their eyes. They are often left in this unbearable
situation for as long as a week. Technicians usually inspect the resulting
injuries to the eyes after the exposure and subjectively determine
an irritancy value for the substance. After the test the rabbits are
usually killed and internal effects on the rabbits are examined.
Corrosivity and Dermal Irritation Tests
Skin corrosivity and dermal irritation tests
are typically conducted by placing a chemical or chemical mixture
on the skins of animals, usually rabbits. The skin is sometimes prepared
by removing layers of skin to cause abrasions. These tests can result
in skin corrosion and irritation, and often cause severe pain.
The Interagency Coordinating Committee for the Validation of Alternative
Methods, a committee consisting of representatives from 14 federal
regulatory and research agencies, recommends using Corrositex, a non-animal
test, instead of painful and subjective animal skin corrosivity tests.
Alternatives to Animal Tests
There is no need for animal tests when
superior non-animal tests exist.
Corrositex is a non-animal based test that
has been validated by the Interagency Coordinating Committee for
the Validation of Alternative Methods (ICCVAM)—a committee that
consists of representatives from 14 federal regulatory and research
agencies and programs.
Corrositex, manufactured by InVitro International, is an in vitro
test that determines chemical corrosivity.
This test replaces the rabbit test of dermal corrosivity. In addition
to Corrositex, other commonly used safety testing methods that do
not use animals are:
- Agarose Diffusion Method
– This alternative to the Draize eye irritancy test (an animal
test) uses human cells.
- Cell and Tissue Cultures
– Cells or tissues can be obtained from human volunteers, surgical
operations, biopsies and post-mortem specimens, and used for in
vitro studies. Some cells can be immortalized to form cell lines
that provide a constant supply of identical test material.
- Clinical Studies – Carefully
managed clinical trials provide information about the safety of
certain products.
- EpiDerm and SkinEthics
– These are three-dimensional human skin equivalent systems. EpiDerm
Corrosivity Test (manufactured by MatTek of Ashland, Massachusetts)
has been validated by the European Centre for the Validation of
Alternative Methods (ECVAM) as an in vitro alternative corrosivity
test and is currently undergoing validation trials by ICCVAM.
- EpiOcular – This is
a three-dimensional human ocular tissue equivalent system which
mimics characteristics of the epithelium of the eye.
- Irritection Assay System
– Manufactured by InVitro International, this is a standardized,
quantitative in vitro test method that can be employed to detect,
rank, and predict the ocular and/or dermal irritation potential
of cosmetics, consumer products, pharmaceuticals, and chemical
raw materials. This advanced technology enhances and replaces
InVitro International’s earlier Eytex and Skintex products.
- Human Keratinocyte/Neutral Red
Bioassay – Cells that are representative of the eye and
skin epithelium and human cells that are derived from donors.
November 2001
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