In toxication and also for evaluation of the level of drug circulating in the body over a determined period of time. Urine or oral fluid drug levels show transient changes in levels of drugs in the body over a short period (hours), the analysis of hair samples provides an integrated picture of drug use or abstinence over a much more extended time frame (weeks, months and years). This has led to the big increase in the use of hair samples in the detection of drug use. The levels of drugs detected in hair are currently best used as a guide to changes of use in the individual when sectional analysis is performed, or two different periods are compard in the in the same individual. This attribute can be used to monitor drug use patterns, demonstrating increasing or decreasing doses being used by the same individual over longer time periods. Another advantage of hair testing is that a subsequent sample could be taken and similar period being re-tested, provided the hair has not being cut short. A hair test can provide useful information after positive urine or oral fluid, on the drug habit of an individual, particularly in the workplace setting or for cause testing. This presentation will focus on the basic explanation about the biology of the hair, some metabolism aspects, differences among matrices, and the use of segmentation in hair, what can affect the result, some important aspects of hair collection, analytical issues and finally a quick explanation about the Case of the Brazilian legislation.
