Many animals were sacrificed for animal experiments to confirm the safety of drugs and cosmetics. However, from the viewpoint of animal welfare, it is required to change the test methods used for life science research to methods that do not use animals as much as possible, "alternatives to animal testing". The methods investigate the toxicity on cultured cells or cell proliferation potential by measuring the amount of enzyme that leaks when cells are damaged by a sample such as a drug or utilizing intake of dyes by living cells. "alternatives to animal testing" are cheaper and need less time and effort compared with methods using laboratory animals. It is possible to objectively measure toxicity.