Some of the first tests to be developed and required by regulatory agencies in the U.S. and throughout the world included the Draize tests for eye and skin irritation and the LD50 test for acute toxicity. Nonetheless, developments within science were causing some to question the validity and usefulness of some animal tests. For example, in 1976, Swiss toxicologist Gerhard Zbinden, then director of the Institute of Toxicology at the University of Zurich, charged that the LD50, a test used worldwide to establish acute toxicity by determining the amount of a substance required to kill half a population of fifty to two hundred test animals, was a wasteful endeavor in which scientific inventiveness and common sense have been replaced by a thoughtless completion of senseless protocols. A few years later, Zbinden further alleged that the clinical experience indicated that the LD50 value in animals rarely bears a meaningful relation with the lethal dose in man. The same problem was evident in animal tests for teratogenicity, Ames and Gold indicated, when test animals were fed doses of chemicals which far exceeded the amount of a chemical to which humans were naturally exposed.
Alcohol is the most important known human chemical teratogen.
At the same time that some scientists were instituting a critique of commonly performed protocols and their impact on regulatory policy, a social movement interrogating the human use and treatment of animals began to assert moral and ethical objections to the use of animals for product safety testing. Rats and mice comprised the great majority of laboratory animals, but dogs, cats, rabbits, hamsters, guinea pigs, birds, frogs and primates were also commonly used as research subjects. Within a relatively brief period of time in the early 1980 s, the animal rights movement was able to mobilize large numbers of Americans who objected to the practice of animal testing, particularly of cosmetics. For example, the Draize test for eye irritation was viewed by many animal advocates as a particularly egregious example of cruelty, although it was viewed as a scientific advance when developed in the nineteen forties. In the standard Draize test, a test substance was placed in one eye of a group of rabbits.