Researchers historically gained information about the toxicity of a substance through rodent and other animal studies in which a substance in question was administered to study animals and adverse impacts were observed. However, these studies can often take years to conduct and can be expensive due to the costs associated with housing and care of the animals. This limits the number of chemicals or other substances for which safety can be investigated at any given time. Additionally, there are sometimes limitations to the type of information the studies can provide. While weight change, tumor development, the appearance of lesions, and other adverse events can be observed in the animals, the studies often do not reveal the underlying physiological mechanism being impacted by the substance and causing the adverse health effects to arise.
Given the limitations associated with animal testing, in recent years there has been interest in developing faster, less expensive, and more informative new approaches to gathering toxicological information. These methods, which researchers aspire to develop for use in place of traditional animal testing, are often referred to as new approach methods (NAMs). Of course, before any NAM is used to assess safety, it is critical that the validity and reliability of the method has been established. It should be equally or more informative than existing guideline studies designed to evaluate a substance’s safety. As these NAMs are developed, validated, refined, and adopted, they present an opportunity to: reduce the number of animals used in testing; refine the methods still requiring animals so they are less stressful to the animals; and to replace animal testing whenever possible.
One such new approach method that CFSAN has been working to develop is the use of C. elegans, a tiny transparent roundworm, as a non-mammalian model to screen for chemicals that may be toxic to mammals. Irrespective of the method or methods used to acquire toxicological information, the goal is to be reasonably certain that, at the anticipated exposure levels, the substance in questions will cause no harm.