The Organization for Economic Cooperation and Development
(OECD) has eliminated the LD50 Test, a notoriously deadly
chemical safety test, from its influential testing
guidelines.
The OECD is an inter-governmental alliance that, among other
activities, administers an international test guidelines
program on behalf of its 30 member countries, including the
United States. The guidelines are the consensus of the member
countries, each of which agrees to follow them.
The LD50 Test ban officially went into effect on December
17, 2002, after a year-long phrase-in period. In a practical
sense, the ban means any company that, for example, wants to
secure Environmental Protection Agency (EPA) approval for a new
chemical product could be rejected purely on the basis of using
the LD50 Test. Regulatory agencies such as the EPA can reject
any data derived from the LD50 Test.
Developed in 1927, the LD50 Test was once a cornerstone in
assessing the toxicity of chemicals. The purpose of the test
was to gauge how deadly a chemical would be, following a single
exposure. Chemicals were usually administered via
force-feeding, though sometimes exposure was via inhalation or
absorption through the skin.
The test was designed to determine the dose that kills 50%
of the animals, hence the term "lethal dose 50%" or LD50.
Typically mice or rats were the subjects, but dogs, rabbits,
guinea pigs and numerous other species have also been the
victims.
Animal protectionists have been critical of the LD50 for
decades, given the inhumane nature of the test. Members of the
scientific community itself also began to criticize the test,
noting the large variability in test results when the same
chemicals were retested. Scientists also questioned the
relevance to human safety of a test that relied on such an
extreme outcome—death.
During the 1990s, alternatives to the LD50 Test were
developed that use fewer animals and, in one case, cause less
suffering per animal. These alternatives—the Fixed Dose
Procedure, the Up and Down Procedure, and the Acute Toxic Class
Methods —were each accepted by the OECD. OECD member countries
are now expected to accept data from the alternative tests, in
lieu of the LD50. Alternatives to the LD50 Test that use no
animals whatsoever are being explored in a collaborative study
in Europe and the United States.
"The OECD's elimination of the LD50 Test from its guidelines
is a milestone in the history of both animal advocacy and
alternative methods," according to Dr. Martin L. Stephens, HSUS
Vice President for Animal Research Issues. "Any country that
continues to use this inhumane test is out of step with the
international community."
Sources: OECD, The HSUS
