The practice of testing on animals dates back to ancient Greece, where surgeons would attempt to learn how the human body works by experimenting on animals.  To learn about a certain procedure, such as swallowing, they would cut open a living animal and watch.  Although much of our modern medical knowledge is based on these experiments, we now have the proper tools available to learn from other rescues with a minimum amount of pain, however, in many cases, animals are still used as unwilling participants in research.  Companies that manufacture products such as cleaning detergents, cosmetics, and art supplies, along with companies doing medical research, will routinely use animals to determine how living organisms react to their products, on the assumption that they will react similarly in humans.  In many cases, however, this is not so.  Animal tests are not accurate and data from them cannot be reliably used in many cases; the metabolism and physiology of most animals are far too different from those of humans.

Companies test their products to:

• measure how much of a drug or substance is absorbed into the blood
• see how the substance is broken down chemically in the body
• record the toxicity of the substance and its metabolites (breakdown products)
• determine the speed at which the substance and its metabolites are excreted from the body

    In 1938, Congress passes its  Federal Food, Drug and Cosmetic Act, saying that all food and cosmetics must be proven safe for humans before entering the market.  However, personal care and non-pharmaceutical products are not required by law to be tested on animals.