Alternate Matrices: Meconium, Cord Tissue, Hair, and Oral Fluid

Drug testing commonly involves serum, blood, or urine. More recently, alternative specimens for drug testing have been increasingly used for clinical and forensic toxicology. Examples include oral fluid (saliva), hair, meconium, and umbilical cord tissue. Each of these matrices has unique properties that provide advantages for certain applications. Oral fluid has easier and less invasive collection requirements than urine, the most common specimen for drug screening. Oral fluid drug testing is common in Europe and steadily gaining popularity in the United States. Hair accumulates drugs and drug metabolites and provides a much longer window of detection than blood or urine. Meconium and umbilical cord tissue each allow for assessment of prenatal drug exposure over the course of months. Limitations of these alternative matrices include need for laboratory-developed tests (exception being some oral fluid immunoassays), challenges with the specimen matrix, and incomplete understanding of drug incorporation and kinetics. This chapter briefly describes each of the above alternative specimens in terms of their utility, advantages, and limitations.