Statistics show that animal use in toxicology testing is increasing annually, in part reflecting Registration, Evaluation, and Authorization of Chemicals (REACh) legislation, which proposes to evaluate 30,000 existing chemicals within a period of 15 years. Inhalation toxicity testing of respirable particulate matter (e.g. environmental dusts and engineered nanoparticles) is also generating an expanding burden for safety testing, making it unviable to screen for safety in whole animal models given the high cost and length of time required.
