(Office of Technology) Of the many animals used for experiments, about 90 percent of the animals used are rats, mice and other rodents. Animals such as these are used for two reasons, one because they are readily available upon request, and two because they are cheap which helps aid the large cost of animals experimentation. Although it has been proven, that in many cases, rats and mice are not an accurate subject to test medicines on; their popularity has only grown larger. Mechanize (a travel sickness drug) caused severe deformities in rats, but not in humans, whereas Thalidomide (a sedative drug) caused no reaction in rats but cause deformities in humans. This is only one of the many cases where mice and rats have been found as faulty test subjects. With the wide range of animals that are available, the tests the are used on them are even vaster. The tests are broken down into many different categories, which allows scientists to zero in on certain areas of testing and to specify results. The largest and most useful area of testing is called .
Toxicity Testing. In toxicity tests, animals are generally exposed to chemicals in ways that are meant to mimic human exposure, by ingestion, inhalation, skin contact and contact with the eyes. The type of animals used in this field include rodents, dogs, cats, fish, birds (chickens, hens, pigeons) rabbits, frogs, pigs, sheep, and primates. Toxicity testing is aimed at providing information, which can be used to attempt to protect society and the environment against the harmful effects of chemicals. (Boyd, 184) Eye irritancy tests, the largest and most controversial area in toxcity testing, began in 1920. It was introduced because soldiers were exposed to mustard gas in World War I, their eyes began to burn and some lost sight. To understand what the effects of the mustard gas more clearly scientist used rabbits as their test subjects. They would force they eyes of the rabbit open and let mustard gas fester for days, they would then compare their findings to the effects on humans.