Complementing information of Borek, Hair growth varies between 0,7 and 3,6 cm/month, a mean of 1 cm/month is generally accepted.
The Hair growth rate depend of:
- Age
- Gender
- Ethnicity / racial factor (caucasoid type, africoid type or mongoloid type)
- Interindividual variability (e.g: color, density, diameter). The duration of stages growth may
influence length of hair density of a scalp
- Anatomical Region
Acc. to Wenning. Potential Problems with Interpretation of Hair Analysis Results. Forensic Science International (2000)107:5-12, the detection window of hair for cocaine is: [ >3d - m/y].
In the same paper we can find information about cut-off values and Levels of Positivity, cut-off Value and Frecuency of Consumption, Relationship between drug dose and hair concentration and Time course of appearence in hair.
FOR COCAINE: (cut-off value and levels of positivity)
For the Cut-off 1ng/mg
Levels of Positivity: LOW (<4 ng/mg) ; MEDIUM (4-20ng/mg) and HIGH (>20 ng/mg)
Finally, The Hair sample Collection is cut hair segments at the base at the crown AS CLOSE TO THE SCALP AS POSSIBLE. If the samples are shorter than 3cm, we'll need collect hair from pubic zone.
Chiralic