A hair-sampling technique used to catch rapists and identify unfit parents in custody battles is to be used to track down drug cheats in sport.

Scientists working in the judicial system from this week will offer British sports chiefs the test for anabolic steroids, which they claim can identify systematic doping offenders more accurately.

Unlike urine testing, which only detects illegal substances between two and five days after they have been ingested, hair samples offer a “telltale history” of a person’s consumption patterns for up to a year, depending on the length of their hair.

“Athletes taking drugs will use them in training and can simply stop a few days before a urine test. If you want a longer window to see what drugs were used, the best demonstration is hair,” said Pascal Kintz, president of the International Association of Forensic Toxicologists, who analyses blood, urine and hair samples at a laboratory in Strasbourg.

Human hair grows on average by 1cm a month, so even cheats with a “number one” crop (3mm) could not evade detection unless they stopped taking drugs ten days before providing a sample.

The test can also be carried out on body hair, so athletes with bald or wet-shaved heads would also expect to be caught out.

The process, known as liquid chromatography, is often used in biochemistry. It has been employed in the British criminal justice system since 2005, most commonly by child protection agencies in custody battles where parents are suspected of drug or alcohol abuse.

It was widely rumoured that Britney Spears, the American pop singer, shaved her head to avoid such a drugs test ordered by a judge during a custody battle with her former husband.

Trimega, the company offering the test in Britain, is based at the Old Bailey and works mainly with solicitors and social workers. The test, which stands up in court, requires a tuft of hair about the diameter of a pencil in length. A sample 1½in in length usually provides a 90-day history.

“Hair testing is the gold standard for cases where children are at risk, so why can’t we use the same technique to establish whether people should be allowed to participate in sport?” Avi Lasarow, the managing director of Trimega, said.

The technique is becoming employed more widely in Britain. Trimega signed a contract with the Nursing and Midwifery Council recently to test their members and is in negotiations with an airline about testing 2,500 pilots to find alcoholics and a security company to screen potential nightclub door staff for steroid abuse.

Yet it is not fully recognised by the World AntiDoping Agency (Wada), whose rules govern international sport, including the Olympics. Under existing regulations, no results taken from samples of hair, nails, oral fluid or other biological material can override the findings from urine or blood.

“Hair testing is not considered sufficiently reliable for application in antidoping by the overwhelming majority of the experts we have consulted,” a Wada spokesman said. “Most consider that urine and blood allow more accurate analysis.”

Hair testing was first used in sport during the Tour de France in 1998, nicknamed the Tour of Shame for its drug scandals. One reason why it may be shunned by sports governing bodies is cost. Hair sampling, at £490 per test, is nearly five times as expensive as blood or urine testing.

Strands of evidence

Liquid chromatography: how it works

A lock of hair (60-80 strands) is cut from the head and measured to set a timeframe. It is washed to avoid contamination. The hairs are then cut into small pieces of less than 1mm and soaked overnight in salt water at 40C (104F). Any drug or alcohol residue is extracted from the solution, which is purified and analysed