Since hair growth is fed by the bloodstream, the ingestion of drugs of abuse is revealed by analyzing a small sample of hair. Hair testing is the most accurate and effective method of finding users of drugs of abuse. Using a small sample of hair cut at the scalp, hair analysis evaluates the amount of drug metabolites embedded inside the hair shaft. It takes approximately 4-5 days from the time of drug use for the affected hair to grow above the scalp. Hair differs from other materials used for toxicological analysis because of its unique ability to serve as a long-term storage of foreign substances with respect to the temporal appearance in blood.
When detecting if there are any drugs in the hair of the person the testing would show what’s in the hair not on it. When you dye your hair, do any treatments, or wash it you’re not affecting the detection at all. Drugs are actually incorporated into the hair shaft from the bloodstream. Severe chemical washing and bleaching removes drugs on the hair. There may be times when it lowers the level in the hair slightly, but it will not remove the drug completely. So after doing these treatments on your hair the drugs will still be present during the testing.
Usually when the testing will take place the people will wash the hair and test the washes to make sure all the drugs are off the outside of the hair before continuing. They should assure that any drug they detect is found directly from within the hair. Dyeing the hair doesn’t affect the test results at all , since you’re just changing the color of the hair and nothing is being done to the inside of the hair.
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