By knowing the range of potential adverse effects of substances, toxicologists can judge a product's relative risk or safety under various conditions. For example, some materials may have little effect if applied to the skin, but serious adverse effects if ingested. Such factors are important in deciding if a chemical or product mixture is safe to use in the amount and manner proposed.
Scientists follow many steps to determine safety risks.
For example, if the pH indicates the product may be corrosive, then clearly it will irritate the skin or injure the eye. Toxicologists don't need to conduct eye or skin irritancy testing on these types of chemicals. Often, additional animal testing is not required for minor changes in materials already approved. When animal testing is needed, it usually involves new ingredients or new combinations of materials. In these cases, there's no existing safety information and current non-animal methods cannot provide complete safety data.