ENVIRONMENTAL CONTAMINATION CAUSES POSITIVE HAIR ANALYSIS RESULTS|
Smith F.P., Kidwell D.A.*
Department of Justice Sciences, University of Alabama, OB15 UAB, Birmingham, AL 35294, USA
* U.S. Naval Research Laboratory, Code 6170, Washington DC, 20375, USA
Despite the scientific literature's extensive documentation of environmental contamination problems, governmental and commercial laboratories continue to offer hair analysis as a means to identify cocaine use. Due to human subject concerns, early reports of environmental exposure either (1) did not directly involve human subjects or (2) when they did involve human subjects, they did not accurately simulate a drug user's environment in either duration of exposure or amount of drug. Results presented here are the summary of two sequential research projects testing known cocaine-dependent adults living with presumed non-using children. Hair from adult subjects contained cocaine in 92% of the cases (33 positive/36 total) while hair samples from the non-using children contained cocaine in 88% of the cases (51/58, by GC/MS, LOD = 0.05 ng/mg hair). Similarly, forehead skin swabs contained cocaine in 94% of the adults and 87% of the children, (by RIA and GC/MS, LOQ = 1.4 ng/swab). Saliva specimens contained trace concentrations of cocaine in 5 of the adults and 2 of the children children (by RIA, LOQ = 1.6 ng/mL saliva). Urine collected in the second study (by RIA, cut-off concentration = 300 ng benzoylecgonine/mL) indicated recent cocaine ingestion in 19% of the adults and none of the children. The large number of positive skin swabs shows recent and likely ongoing environmental exposure. The short-term measures of drug use (aliva and urine) did not parallel the positive hair analysis results. The large amounts of contamination observed resulted from human subjects living in the environment of active cocaine use. This is in contrast to the lower contamination reported with occasional workplace contact. In random samples of a large population one may observe false positives in non-users because of their living arrangements or other exposure.