Many animals have been sacrificed in animal experiments to confirm the safety of drugs and cosmetics. However, from the perspective of animal welfare, there is a growing demand to transition to alternative test methods that minimize the use of animals in life science research. These methods involve examining the toxicity and cell proliferation ability of cultured cells by measuring the amount of enzymes that leak when cells are damaged by a drug or other sample or by utilizing the uptake of dyes by living cells. Compared with methods using experimental animals, animal testing alternatives are inexpensive, are less time-consuming, and allow for objective measurement of toxicity.