How drugs affect hair

MPU info

Anyone who had to surrender their driver's license because of drug or alcohol consumption must provide the MPU with a certificate of abstinence that documents a change in consumer behavior. This evidence can be provided by urine screening or hair analysis. While a hair analysis can check a certain period of time, a urine check can only record the values ​​at a certain point in time. Several checks are necessary for a urine screening, usually four checks every six months or six within a whole year.

Hair Analysis or Urine Screening?

Many experts like to see a urine screening, but in practice the hair analysis method is gaining ground due to some advantages. Hair analysis is less time-consuming than urine screenings. The necessary evidence can often be provided with a single hair sample, while several urine checks are always required. Sampling is also more convenient: the urine sample required for the control must be submitted under the supervision of a doctor in order to avoid attempts at deception.

Removing hair is much more comfortable for most people. Urine controls may be announced to those affected a maximum of 48 hours in advance, absences of the subjects are not possible or must be plausibly explained and announced. Hair analyzes, on the other hand, are easier to plan and carry out for those affected. From a financial perspective, hair analyzes are also more beneficial than urine screenings.

Hair analyzes enable evidence over certain periods of time

A major advantage of hair analysis compared to urine screening is that an examination of the hair can determine values ​​from a previous period. A urine screening, on the other hand, can only show a current value that says nothing about the past weeks. In practice, one month is recognized for one centimeter of the main hair. When it comes to the consumption of drugs, usually six centimeters of the hair are analyzed, when it comes to the question of alcohol consumption, three centimeters is sufficient. This means that a hair analysis can check drug consumption for the last six months or alcohol consumption for the last three months.

Which substances can be detected with a hair analysis?

There are a large number of substances that can be built into the hair and are detectable there. As long as these substances are in the blood of the test person and get into the hair follicle, they pass into the hair. The substances that get into the hair include:

  • cocaine
  • amphetamine
  • Amphetamine derivatives
  • Methadone
  • Benzodiazepines
  • Morphine
  • THC-COOH, a breakdown product of cannabis and
  • the alcohol markers ETG (ethyl glucuronide) and FSEE (fatty acid ethyl ester)

It should be noted that not all substances get into the hair equally. Cocaine, amphetamine and morphine are basic compounds that are built into the hair very well. Acid compounds like THC-COOH, on the other hand, are rather poorly incorporated. Even the one-time consumption of certain substances can be proven with a hair analysis.

What can influence the analysis result?

Certain foods and drugs can influence the results of the analysis. Alcoholic meals and medication, such as over-the-counter flu drugs, can affect the result just as much as meals containing poppy seeds. But staying in rooms where cannabis is smoked can also be reflected in the results of the hair analysis. Because the hair can also be contaminated from the outside, for example through dust or smoke. Even thorough washing doesn't always help. Although it can often be seen whether external contamination may have occurred, evidence of abstinence can still be refused in such a case.

The condition of the hair itself can also have an influence on the analysis result. Heavily pigmented, i.e. darker hair, can store more substances than less pigmented hair. This means that a blond person and a black-haired person store different concentrations in their hair even if they have consumed the same amount of cocaine. The extreme case here is conceivable where two people get different results after consuming the same amount of cocaine, for example one person gets a normal result while the other tests positive.

How does a hair analysis work?

In order to carry out a hair analysis as part of an MPU, the identity of the test person must first be checked. This prevents those affected from sending another person to this appointment instead of you. After that, two hair bundles are first removed from the test person. Both bundles are about the thickness of a pencil. Usually the hair is removed from the back of the head. Different points can also be used for test persons who have only a few hairs. In exceptional cases, hair can also be removed from parts of the body other than the head. However, it is more common to use urine samples if enough hair cannot be cut off on the head. After the hair samples have been taken, the test person must certify that they have no longer come into contact with the hair sample. This regulation also serves to protect against forgery. Until the actual examination of the two hair samples (sample and reserve sample), the hair strands are wrapped in aluminum foil. The side of the strands near the scalp is marked. Both the length of the hair to be examined and that of the remaining hair are measured and documented with millimeter precision.

Drugs can only be made visible in the hair two weeks after consumption. It takes about a week for the substance to settle in the hair and for the corresponding area of ​​the hair to grow out of the scalp. It takes another week before the hair is long enough to be cut off with the required length of two millimeters.

Two hair analyzes are required to prove drug abstinence for a period of one year. Here, six centimeters of hair are checked each time. Four hair analyzes are necessary to prove that you have abstained from alcohol for a year. Here three centimeters of hair are examined.

It is recommended to examine the hair segments that correspond to the period that is three months after the last consumption at the earliest. In the case of chronic consumption, it can even make sense to wait up to six months after the last consumption.

Which requirements have to be fulfilled for a hair analysis?

In order to receive a certificate of abstinence that is recognized by the MPU, certain conditions must be met. Sampling and hair analysis may be carried out by the following bodies:

  • Coroner
  • Doctor in a fitness assessment center such as TÜV or Dekra
  • Doctor or toxicologist from an accredited forensic laboratory
  • appropriately qualified doctor from a health department
  • appropriately qualified public service physician

Every body who carries out a hair analysis is obliged to prepare a final report that documents the results. In addition, the general conditions of the abstinence program, any absenteeism of the subject and the analysis methods must be specified in this report.

What do test persons have to consider during a hair analysis?

Subjects whose hair is tested for alcohol consumption should not only refrain from alcoholic beverages, but also from foods and drugs that contain alcohol. Alcohol-free beers and wines can also contain small amounts of alcohol, which have an effect on the analysis result and possibly exceed the limit value. To prove abstinence from drugs, those affected should refrain from using poppy seed and hemp products, which can falsify the analysis results. Staying in rooms where drugs are consumed can also affect the result. Substances in question can also be absorbed directly through the hair under certain circumstances. Anyone who has a hair analysis carried out should refrain from bleaching or coloring their hair. Colored hair is accepted in drug analyzes, but only in connection with an additional urine test over a period of six months or a supplementary hair analysis of six centimeters of untreated hair.

Since it is possible that the substances consumed will still get into the hair long after consumption, it is advisable to wait a while after the last consumption before the hair is analyzed. Depending on the intensity of consumption, a period of between three and six months after the last consumption is recommended.

The phases of hair growth and their importance for the analysis

After a substance has been built into the hair, it grows with the hair, moving further and further away from the scalp and the hair follicle. One could look at the hair like a tachograph documenting the intake of certain substances. The hair grows about an inch a month. This means that substances that have been consumed in the last 6 months can be detected in the first six centimeters of the hair from the scalp. However, hair grows irregularly and goes through different cycles. Three growth phases can be distinguished:

  • Growth phase
  • Transition phase
  • Resting phase

Most of the hair on the human body, around 90 percent, is in the growth phase. The duration of the growth phase varies from person to person. The transition phase follows the growth phase, in which the hair separates from the hair root. This is followed by the rest phase. In this the hair is shed and a new hair is produced.

For the analysis of the hair this means that one centimeter of the main hair does not necessarily show the period of a month. Hair in the resting phase can therefore also show substances in the tested six centimeters that were consumed significantly more than six months ago.

In addition, the test period cannot be precisely limited in every case. This may be the case for someone who has consumed particularly high doses in the past, as well as for someone who consumes substances that work into their hair very easily. These can then leave traces long after consumption. It is also possible for substances to migrate in the hair. They can even spread to other hair.