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EFFECTIVE WASH PROCEDURE


CRITICAL IN HAIR TESTING BY JIM DYKE, PSYCHEMEDICS CORPORATION


Hair analysis for the detection of drug use in workplace testing continues to grow in popularity as a result of its wider window of detection and ability to detect repeat drug users. One aspect that has lacked agreement in the field, however, is how best to ensure that a positive result is due to ingestion rather than environmental exposure.


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air analysis technology capitalizes on the way the body metabolizes ingested drugs as


they flow through the blood stream and deposit in the cortex of the hair. There are two important regions in the basic structure of hair that are involved in hair analysis: the cuticle and the cortex. The cortex is the region inside the hair shaft that is fed by blood while the hair is forming in the follicle. The cuticle is the region on the outside of the hair shaft that is affected by the environment. The hair acts like a tape recorder—“recording” the deposits inside the hair in proportion to use over time as drugs are deposited. To ensure accurate hair testing results,


it is important to eliminate the possibil- ity that the results are being influenced by drugs deposited on the outside of the hair from contamination versus drugs deposited on the inside of the hair from ingestion. Tis is critical to provide accurate test results and to prevent false positives.


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Wash Procedure Can Answer the Challenge of Contamination Washing the hair samples prior to analysis is a standard laboratory procedure that has been actively studied since the early years of hair analysis research, when the need for a wash that addressed the challenges presented by contamination was realized. Fairness and accuracy can be achieved by implementing an effective wash procedure that addresses the challenges of ensuring that the hair test is only analyzing what is inside the hair and was a result of drug use. Accurately identifying ingestion of drugs


is dependent on factoring out drugs pres- ent from other sources, including environ- mental contamination and sweat. Envi- ronmental contamination can be caused by a variety of factors including: during use of the drug, secondhand smoke or being in the vicinity of drug users, or from residues leſt in an environment by various means. With sweat, ingested drugs can be


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