Adulteration is the altering of a specimen to mask the presence of drugs. This can be attempted by several methods, such as:
- Dilution, in which other fluids are introduced into the specimen to reduce the concentration of drugs.
- Addition, in which chemicals or elements such as bleach, vinegar, eye drops, apple juice or soap are introduced to mask the presence of drugs.
- Substitution, in which an attempt is made to substitute a urine specimen from another person or an animal.