A number of other government regulatory agencies also either began to conduct testing themselves or to require tests of the products they were responsible for regulating. As public pressures to protect the consumer heightened, additional legislation in the 1950 s and 1960 s introduced or strengthened regulations concerning the premarket testing of food additives, color additives, insecticides, drugs, and other products. At the same time, concerns about toxins in the environment and in the workplace led to further legislation concerning the testing and control of toxic substances. These developments contributed to a significant increase in toxicity testing, most of it involving the use of animals. Traditional toxicology is based upon the assumption that physiological processes in mammals are much the same and that a substance which is toxic to a small mammal like a rodent is likely to prove equally toxic to a human being, if the quantity of the substance is adjusted according to body weight and other factors.
Early tests mirror the concerns of the time.
For example, in the wake of the cosmetics scare in the 1930 s, the Draize tests for eye and skin irritation were developed. The LD50, a test developed in 1927 to measure the potency of biological preparations such as vaccines was converted to use as a predictor of acute toxicity, establishing the lethal dose of a drug, chemical or other product. The LD50 assesses acute oral toxicity, and provides an estimate of the quantity of a substance which will kill half the members of a test population. Like the Draize test, the LD50 has been the focus of much criticism by both scientists and animal protectionists who object to exposing animals to high doses of toxic substances. This approach has been dubbed by critics the kill em and count em school of testing.