Napoleon's favorite color was green - so his wallpapers had that color. That was probably doomed to him: He died of chronic poisoning with arsenic, part of the then used green dyes. Maybe he was also deliberately poisoned. How do you come to such assumptions, centuries after his death? His hair showed the scientists of the puzzle solution.
Hair is made up of horny structures that outgrow the skin. Its lower part, the hair root, participates in the metabolic process, then it becomes horny and is pushed outwards, on the average one centimeter per month. Hair is not really necessary - its tasks Thermal insulation, friction reduction and participation in the sense of contact can also be well taken over by other structures. Psychologically, they have a higher status - as part of the individual form of expression they are formed and pampered, cut and lengthened, smoothed, curled and dyed.
Searching for clues on the head
Especially in legal and environmental medicine, hair is used to detect toxins, drugs and trace elements. They are exceptionally good for this - such substances and their degradation products like to accumulate during the keratinization in the hair structure and remain there even after a long time detectable. If the liver degrades the excessively consumed alcohol within a few hours, so that the driver's license is not taken off even during an alcohol test, hair will reveal even after weeks whether the hair carrier smokes.
Advantages and disadvantages of a hair analysis
The advantage is that the hair is not like blood or urine just a snapshot of the current body events, but chronic stress or poisoning over a longer period of time reflect. The disadvantage is that not all substances are equally well detectable and that chemical treatment of the hair such as dyeing or frequent swimming in chlorine water can make the result of the analysis unusable. In addition, not only by eating, inhaling or injecting ingested foreign substances in hair are detectable, but also direct contact z. B. with dusts can lead to deposits. Differentiating these types of uptake is difficult for certain substances.
Execution and evaluation of hair analyzes
For the sample, about 500 mg of hair (about 2 tablespoons full) or 2 tufts of hair each with a diameter of 5 mm are needed. The length should not be less than 2-3 cm. The hair is cut off directly on the scalp. The details of the removal are best coordinated with the respective laboratory. Cosmetically treated hair (dyeing, tinting, perm etc.) can not be used. In order to be able to assess the results correctly, ideally other factors should also be taken into account. These include factors such as gender, age, season, type of living, drinking water content, smoking behavior, dust exposure at the workplace, metal precipitation in the interior or lead in the outside air and hobby activities. In addition, the documentation of hair color, hair type, information on hair washing and shampoo used, treatment of hair and swimming habits is relevant.