Scientific literature and recent data produced at RTI International indicate that environmental contamination may be a significant confounder to interpreting hair testing results. The purpose of RTIs proposed study is to 1) examine the impact of environmental contamination on drug tests conducted with human hair, 2) examine the effectiveness of a hair decontamination procedure used by forensic laboratories, and 3) look for markers to distinguish between contamination and ingestion. Using human hair samples and a surface contamination model developed at RTI, we will examine environmental contamination by methamphetamine and heroin by dry transfer of drug to hair and by mimicking in vivo hygienic treatment conditions of hair. Both in vitro contaminated non-drug user hair and hair samples from users with a known drug history will be analyzed using liquid chromatography-tandem mass spectrometry (LC-MS/MS) with and without decontamination. We will monitor the levels of the parent drugs, as well as several known metabolites. In addition to monitoring metabolite formation, we will also determine if a mass spectrometry (MS)!based imaging technique"matrix assisted laser desorption ionizationtandem time of flight (MALDI-TOF/TOF) MS"can be used to localize the site of incorporation of the drugs into hair as an alternative method to provide an indicator as to the route of incorporation (e.g., contamination versus consumption). The results of RTIs study may help those responsible for drug testing to distinguish between the presence of drugs in hair as a result of external contamination from drugs present as a result of drug use. These results may directly affect policy implementation for drug-related crimes, workplace drug testing, and other uses of hair testing. RTIs unique relationship with many forensic toxicology laboratories and organizations across the country will allow for wide dissemination of the study results to the forensic toxicology community. In addition to submitting regular financial reports, a semi-annual progress report, and a final report to the National Institute of Justice (NIJ), RTI plans to publish the study results in two prominent forensic toxicology journals and present the results at the annual meetings of leading forensic organizations. Results will also be made available as an online presentation to facilitate dissemination of results to laboratories with limited funds available for travel to scientific meetings. All analytical data and project reports will be made available for archiving by the NIJ Data Resource Program.