Findings of illicit drugs in hair of children at different ages.

Hair is a preferred material to detect exposure or use of illegal drugs in children. In the present study, we investigated a total of 387 hair samples for commonly applied illegal drugs of children up to 16 years. Analysis was by liquid chromatography/mass spectrometry with LOQs of 0.01 ng/mg hair for all analytes except tetrahydrocannabinol carboxylic acid with an LOQ of 0.1 pg/mg hair. Results were firstly compared with our in-house statics on results from adults' hair, and secondly to literature data. We started from the assumption that drug concentrations decrease with increasing age.Results were assigned to 4 different age groups (< 1 year, 1-< 6 years, 6-< 14 years, 14-16 years). As expected, higher results were obtained in age groups 1 and 2. The lowest concentrations were present in age group 3, whereas an increase could be observed in group 4 except heroin. In babies, positive results may be due to in utero exposure, breast milk feeding, and a close physical contact. All drugs under investigation such as cannabinoids, cocaine, amphetamines, and opiates have been detected in breast milk as well as in skin excretions such as sebum, sweat and cutaneous cells. For most drugs, average concentrations in children hair were lower than in adult hair when compared with our in-house statistics. Interestingly, the increase of cannabinoids, cocaine, and amphetamines concentrations in adolescents' hair points to a deliberate use of these drugs possibly in addition to passive exposure. This observation shows that age groups 1 and 4 are most vulnerable if caregivers or parents are drug users, even if the sources of positive drug findings differ.