Another important thing regarding scalp hairs in childrens/adults
Hair analysis of more than 140 families with drug consuming parents.
Comparison between hair results from adults and their children.
The comparison of hair results within families gives a deeper insight in the drug situation, often enables the identification of the drug user and is helpful for social and legal decisions to improve the conditions of the children.
pubmed.ncbi.nlm.nih.gov
Hair of young children differs from adult terminal hair in
structure as well as in growth properties. Although there is
only limited scientific literature about peri- and postnatal hair
properties and growth, it is known that at the time of birth
the scalp hair follicles are still synchronized with the frontal
follicles converting to the telogen stage whereas the follicles of the
occipital scalp region are still in the anagen stage and convert to
the catagen and telogen stage in the 8th to the 12th postnatal week.
The next hair cycle is not synchronized anymore and the prenatal
hair is completely replaced between 6 to 12 months after birth.
....
In comparison to adults, the hair of young children is thinner
and more porous. This facilitates external incorporation from own
or parents sweat, sebum, smoke or contaminated environment but
also elimination, e.g. by shampooing. It makes, together with
variations in growth rate and in the ratio of anagen/telogen hair,
the chronological interpretation of sectional hair analysis from
young children more complicated.
However, from the
viewpoint of growth rate and structural properties, at the latest
above an age of three years children hair can be interpreted in the
same way as adult hair .