Scientists still don’t know enough about the complex interaction of the body systems of living beings to reproduce certain effects in artificial environments outside the body. A single cell culture cannot mimic the complicated physiological actions that take place in whole systems such as the neurological, endocrine, immune and circulatory systems of a whole animal. How do we know what happens when a chemical is absorbed into a body’s brain or its other organs? How can we measure blood pressure in a test tube? Years of work are needed to develop and validate any toxicity test before it can be used as a reliable predictor of adverse effects on humans. As for computer studies, these generally rely on data from previous research using animals and humans.
There is no guarantee, but we can hope that product safety testing may someday prove to be possible without reliance on laboratory animals. Yet, there may always be a need for animal tests of potential new medications, at least through the span of our lifetime. Scientists at work on a cure for a disease must first find a model for the illness itself. Neither the cure nor the illness can be duplicated fully in a computer program or indeed anywhere outside a living body. Under international law, human beings cannot be subjects for such experiments.
