SINGAPORE, Nov 8 — Singapore’s Central Narcotics Bureau has been using a hair test to study past drug usage histories among former drug abusers as part of an ongoing effort to combat drug use in the city state.

Fifteen people serving two-year supervision orders comprise the current cohort of former drug users in the study. The bureau plans on expanding the study to include 100 people by the end of next year.

The hair test can detect drug usage up to 90 days prior to sample collection, which is considerably longer than the week-long detection window in urine and saliva drug tests.

Drug metabolites in the blood circulate into hair follicles and deposit into the hair shaft. Hairs typically lengthen at approximately a centimetre per month. Therefore, three centimetres of hair is sufficient to detect drug use up to three months ago.

The hair testing system can accurately detect trace levels marijuana, amphetamines, cocaine, opiates and PCP. Hair samples must be sent to laboratories for analysis. Results have a two to three-day turnover time. — Reuters