DH Deciphers | What is a hair follicle test? Does it convulsively prove illicit drug use?

For the first time ever, police in Bengaluru have used the hair follicle test to establish illicit drug use.

On August 24, the Karnataka government announced the results of tests conducted on two Kannada actresses and four other celebrities in the Sandalwood drugs scandal that broke out last year. All of them were found to have consumed illicit drugs, according to the test report.

You may be wondering what the hair follicle drug test is and how accurate it is. So here's a ready reckoner on it:

What is a hair follicle drug test and why is it done?

The test screens for the use of illicit drugs such as cocaine, MDMA and heroin, or the misuse of prescription medication, says Dr Dinesh Rao, a forensic expert. The hair follicle test is used to analyse drug use in the past 90 days while recent drug consumption can be detected by blood and urine tests.

Police use the test to press charges under the Narcotic Drugs and Psychotropic Substances (NDPS) Act, a stringent law that criminalises the production, possession, sale and consumption of commercial-quantity drugs.

How is the test conducted?

Small amounts of hair (20-30 strands) can be taken from any part of the body using scissors, though generally they are plucked from the scalp and the hair root. The hair samples are taken by doctors under the supervision of forensic experts.

Gas chromatography and mass spectrometry are the two techniques used to analyse the hair samples for the presence of drug residues.

What if someone unknowingly inhales an illicit drug? How does the test establish that?

The accused have admitted to attending parties but denied consuming any drugs. So even if their test report is positive, isn't it possible that they may have inadvertently inhaled illicit drugs?

Rao, the forensic expert, busts this myth: the hair follicle drug test is usually used to determine the consumption of synthetic drugs, such as PCP (phencyclidine), cocaine, MDMA and heroin, none of which can be inhaled passively, unlike ganja.

Synthetic drugs accumulate in the hair through blood circulation or metabolise after absorption through lungs, ingestion, snorting, or injection. Passive smoking of ganja could show minute levels of consumption, which the NDPS Act doesn't penalise.

Cocaine, LSD, heroin and MDMA are known narcotic and psychotropic drugs, while ganja is a deliriant or hallucinogen.

Is the test report admissible in court?

The NDPS court does admit the report of a hair follicle test but the police also need to establish the method of procurement, sale, trafficking, and place of consumption of the drug/s. Investigators also rely on witness statements, technical evidence and money transactions, if any, to build their case.

What bearing will the test report have on the Sandalwood drugs case?

One of the two Kannada actresses charged in the case has disputed the findings of the test and vowed to challenge it legally.

A senior officer in Bengaluru police refused to describe the test report as the most clinching evidence in the case. "We filed the charge sheet in the case long before the test results came. We don't see the test report as the be-all-and-end-all. We have already established how the drugs were trafficked, the contacts between peddlers and users, and how money changed hands. Last but not the least, we have witness statements," explained the officer, who would not be quoted.

He continued: "Nonetheless, the test report will be vital evidence that substantiates our investigation."

While a hair follicle drug test can determine the exact drug consumed, the officer said they had chosen not to disclose the same. "We have only stated that the report of the test taken by the accused has come back positive," he said.