Because every drug taken becomes a permanent part of the user's hair, laboratory analysis of hair can reveal the presence of a variety of drugs, including HEROIN, COCAINE, AMPHETAMINES, PHENCYCLIDINE, MARIJUANA, NICOTINE, and BARBITURATES. Hair analysis is widely accepted by courts, parole boards, police departments, and employers around the country for detecting long-term drug use. It's also increasingly used to determine maternal/fetal drug exposure and to validate self-reports of drug use.

Unlike urinalysis, which can only detect drugs ingested within the past three to four days, hair analysis can reveal the ingestion of drugs during the past ninety days (or longer). Since hair grows at a relatively constant rate of¹⁄ 2 inch (1 cm) per month, segmental analysis of hair strands could localize the time of drug exposure to within as little as one particular...