Segmental hair analysis

Almost all drugs of abuse and most pharmaceutical drugs will be incorporated in hair. The incorporation is mainly via a direct transfer of substances from the blood to the hair root, but a certain amount is probably incorporated via sweat glands surrounding the intradermal part of the hair. Regardless of which route predominates, the drugs incorporated in hair will bind to the melanin or, to a lesser extent, to the keratin molecules in hair. The drugs will then gradually be found further away from the scalp as the hair strands grow, implying that segmental hair analysis can provide a map of the drug exposure over time. In collaboration with the Department of Forensic Toxicology in Linköping, a method to analyze different classes of illicit drugs and some selected pharmaceutical drugs, also abused, has been developed. In particular, this strategy allows for a better understanding of the impact of tolerance, or loss of tolerance, to opiates of an opiate overdose victim. Indeed, we have found that almost 80% of fatal opioid intoxications were preceded by an at least 2-week period of discontinued opiate intake, suggesting that abstinence is strongly associated with such deaths. Hair analyses can also reveal alcohol exposure. Markers such as ethyl glucuronide and ethyl sulphate are incorporated into hair in relation to their blood concentrations, so the alcohol consumption over time can be fairly well be estimated by segmental hair analysis. Future studies will include comparison of pharmaceutical drugs of interest in hair with drugs detected in postmortem blood in fatal intoxications.