Glossary Terms – R


Reducing agent

Reducing agents are ingredients which during their reaction with oxidizing agents lose electrons. Reducing agents commonly contribute hydrogen to other substances. They can be used as antioxidants since they scavenge oxygen. In addition, reducing agents have the ability to split disulfide bonds in hair.

Reference dose

A reference dose (RfD) is the term used by the Environmental Protection Agency (EPA) for an estimate of a daily exposure to the human population (including sensitive subgroups) that is likely to be without an appreciable risk of deleterious effects during a lifetime.


A class of solid or semi-solid viscous organic substances exuded by plants. Sometimes refers to a class of synthetic products with physical properties similar to those of natural resins.


A subterranean plant stem with shoots above and roots below, serving as a reproductive structure, and often thickened by deposits of reserve food material.


RIPT stands for Repeat Insult Patch Test. In RIPT, a small amount of product is applied to the skin of each individual subject and monitored for its effect. Over a certain interval of time, the skin is observed, graded, and tested again.