How quickly does hair grow?
Hair from the scalp is the best hair sample to collect as it has an even growth rate of approximately 1cm per month. The Society of Hair Testing guidelines recommends that
Body hair, such as from the arms, chest and legs has a slower growth rate and grows in a different way to scalp hair. So whilst it can be used as an alternative to scalp hair, it can’t be used for sectional analysis.
It should be noted that drug use cannot be detected in hair samples until two weeks after the event, as it takes that long for the hair to grow from the follicle to the scalp.
When should I use hair testing?
Hair testing should be used to look at historic drug abuse over a number of months, as well as being used as as tool to monitor abstinence.
How much hair is collected?
Two samples (the ‘A’ and ‘B’) are collected. Each is cut close to the skin and is approximately the thickness of a pencil.
What types of analysis can be performed in hair samples?
There are two types of analysis that can be performed on hair:
- Sectional analysis: Scalp hair is portioned into individual 1cm sections to provide an approximate “month by month” report. This can demonstrate patterns of drug use or abstinence by month for a particular individual.
- Overview – Any drug use over that time period can be detected.
Hair from the scalp is most commonly collected, as it has an even growth rate of approximately 1cm per month, so allows for wider insights to be gained during analysis as both sectional analysis and an overview can be performed.
Alternatively body hair can be analysed. Due to the uneven growth rate, only an overview can be provided.