Decigram 1/100th of a gram. Demyelination The loss of the myelin sheath (insulation) around a nerve. Dermal Sensitization Test An assay for immune hypersensitivity of the skin. Dermal Toxicity Toxicity of the skin which can range from mild irritation to corrosivity, hypersensitivity, and skin cancer.  It can result from direct contact or internal distribution of the xenobiotic to the skin. Detoxification A metabolic process whereby a parent substance is changed to a daughter product (metabolite) that has lessened toxicity. Disposition The term used to describe the kinetics of a substance in the body.  It encompasses absorption, distribution, metabolism, and elimination of a chemical. Distribution Movement of a substance from the site of entry to other parts of the body. DNA Deoxyribonucleic acid. The very large molecules in the nucleus of the cell, that carry the genetic information. Dominant Lethal Assay Test A mutagenicity test that can detect heritable dominant lethal mutations present in the sperm as the result of exposure to a substance. Dosage The determination of quantity of a substance received that incorporates the size, frequency, and duration of doses (e.g., 10 mg every 8 hours for 5 days). Dose The amount of a substance received at one time.  Dose is usually expressed as administered or absorbed dose (e.g., milligrams material/kilogram of body weight). Dose-Response Assessment The relation between dose levels and associated effects. Dose-Response Curve A graphical representation of the quantitative relationship between doses of a substance and specific biological effects. DOT Department of Transportation.  A federal agency responsible for the safe shipment of toxic chemicals and other hazardous materials. Draize Test The test for eye irritation in which the test substance is placed on the eyes of white rabbits and observed for 72 hours. Drug Idiosyncrasy An abnormal susceptibility or sensitivity to a drug. Drug Tolerance The unusual ability to endure, without effect, a quantity of a drug that would normally produce biological activity.