Limits of Interpreting A Drug Test
Showing: hair testing

By: Kelly Hack, Content Writer
There are many variables regarding the analyses of substance abuse testing. Clients will often ask about specifics pertaining to the determination of time, dose and frequency when detecting substance(s) of abuse.
When testing a reservoir matrix- a material or substance which can accumulate and retain drug and alcohol biomarkers (eg., urine, blood, hair, nail, umbilical cord, or meconium, etc.), the reported quantitation of a drug or its metabolite cannot be used to determine when/if a specific substance was used, how much of a substance was used or how often a substance was used. Test results show only if a substance was detected or not detected.
A specimen’s window of detection provides an estimated timeframe for detecting substance(s) of abuse. Based on extensive research studies, the generally accepted windows of detection for specimens used in our testing are as follows:
- Scalp Hair- Up to approximately 3 months prior to collection.
- Fingernail- Up to approximately 3-6 months prior to collection.
- Umbilical Cord- Up to approximately 20 weeks prior to birth.
- Meconium- Up to approximately 20 weeks prior to birth.
- Urine- Up to approximately 2-3 days prior to collection.
- Blood (PEth)-May be up to approximately 2-4 weeks prior to collection.
It is important to know that the interpretation of drug testing results may be determined by a Medical Review Officer (MRO). A Medical Review Officer is a licensed physician (MD or DO) who has knowledge of substance abuse disorders and has the appropriate medical training to interpret and evaluate an individual’s positive test result together with his or her medical history and any other relevant biomedical information.1This is an incredibly important aspect of drug testing. A laboratory can detect substances, but an MRO may be used to interpret what that detection means.
1. Journal of Occupational and Environmental Medicine: (January 2003-Volume 45-Issue 1-p 102-103) Qualifications of Medical Review Officers (MRO’s) in Regulated and Nonregulated Drug Testing. Departments: ACOEM Consensus Opinion Statement



When a child is exposed to illegal substance abuse they often also face other coexisting obstacles to a normal life – neglect, abuse, violence, and other vulnerabilities. Substance abuse is a disease, one that often prevents adults from doing what is in a child’s best interests. Our environmental exposure test for children can help.
Our hair environmental exposure test is the only drug test designed to detect passive exposure to drugs and detect both native drugs and drug metabolites in the hair specimen. Drug metabolites are produced in the body only if drugs have been ingested. Children in drug exposed environments are most often not drug users themselves, so drug metabolites are typically absent in child specimens. However, the hair, like a sponge, can absorb non-metabolized drug (native drug) if it is exposed through things such as touching or being in contact with drugs or drug users.
Standard hair tests with other labs will only report a positive exposure result if drug metabolites are detected, even when the native drug is in the child’s hair specimen. Our hair environmental exposure test reports a positive result if either native drugs or drug metabolites are detected.
A hair exposure test can provide evidence of drugs in a child’s environment for the past 3 months. A positive test result suggests that the child has experienced one or more of the following: passive inhalation of drug smoke, contact with drug smoke, contact with sweat or sebum (skin oil) of a drug user, contact with the actual drug, or accidental or intentional ingestion of illegal drugs.
ChildGuard®is the only child hair test designed to detect exposure to native drugs and drug metabolites.

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