Drug Tests Accuracy


Are Drug Tests Accurate? How Teens Cheat the System

Since 2002, when the U.S. Supreme Court ruled 5 to 4 that middle schools and high schools could require random drug tests of students who participate in extracurricular activities, more schools and parents have been testing teens for drug use. A 2006 survey by University of New Hampshire researchers found that roughly 12 percent of school districts nationwide now drug test students. But as quickly as new tests are invented and used, teens are discovering new ways to circumvent them.

Types of Tests

There are five basic types of drug tests: urine, blood, hair, saliva, and sweat. Most drug tests check for cannabinoids/marijuana, cocaine, amphetamines/speed, opiates (heroin, opium, codeine, morphine), and phencyclidine (PCP). More expansive tests can also detect barbiturates, hydrocodone (Lortab, Vicodin), Quaaludes, benzodiazepines (Valium, Xanax, Librium, Serax, Rohypnol), methadone, and MDMA (Ecstasy).

Urine Tests

The most common test used by employers, law enforcement, and in the home is the urine test, which is inexpensive ($7-$50 for the home version) and less invasive than other methods of testing. Home drug tests are available via the Internet, though toxicologists warn that the sample collection process is error-prone and results may not be accurate. Urine tests are primarily used to detect drug use within the past week, though some have been able to detect use up to 30 days later.

Saliva Tests

Saliva tests cost around $15-$75 and are useful for detecting recent drug use, primarily within the past few hours or days. Because they are relatively unintrusive and easy to administer, these tests are becoming more common, though experts caution that there are no nationally accepted standards or cutoff concentrations for detection, making results heavily dependent on the specific product purchased.

Hair Tests

Hair tests are most appropriate for detecting substance use over a longer period of time, usually up to 2-4 months, as traces of use accumulate along the hair shaft. A sample of about an inch-and-a-half of hair is required (a single strand is insufficient). At a cost of $100 to $150, these tests often check for a wide range of substances, and can provide information about the frequency and degree of drug use. Experts warn that minorities are more likely to get a false positive, and simply walking through a room where there is marijuana smoke could result in a positive hair test.

Blood Tests

Blood tests are the most expensive and invasive method of testing, but they are also the most accurate.

Sweat (Patch) Tests

These relatively uncommon tests require the subject to wear a patch for an extended period of time. Since surface contamination on the skin can cause a false positive reading, sweat tests can be questionable in terms of accuracy.

To Test or Not to Test?

The experts are divided when it comes to advising parents to test, or not to test, their teenagers. Sharon Levy, an assistant professor at Harvard Medical School who works with teenagers in a substance abuse program at Children’s Hospital in Boston, questions the reliability of drug tests.

In a study published in Pediatrics, 12 percent of the teenagers in Levy’s program who took tests for drugs had an initial false result. In 6 percent of the 710 drug tests studied, the urine sample was too diluted to read properly (a well-known way to falsify a drug test), and the other 6 percent came up positive because the patient had taken a legitimate prescription drug or over-the-counter medication.

According to Levy, “Drug testing is really a very, very complicated procedure. Tests can be negative even if a kid is using drugs. Tests can be positive even if a kid is not using drugs.”

Drug testing has serious limitations with dozens of workarounds and ways to manipulate the results, explains Levy. For example, most tests only check for a set panel of drugs, so a negative result may not give an accurate portrayal of the child’s drug use. Also, depending on the type of test used, abstaining from drug use for 48 to 72 hours can produce a misleading result.

“Just drinking two half-liter bottles of plain water will dilute the urine so much that it’ll drive detection of substances below detection level,” says Levy.

John R. Knight, MD, of Children’s Hospital in Boston and Cynthia J. Mears, DO, of Children’s Memorial Hospital in Chicago authored a policy statement for the American Academy of Pediatrics that appeared in Pediatrics, expressing concern that drug testing doesn’t appear to reduce substance use among teens, and that it creates distrust between parents and children.

In addition, Knight notes, the tests are costly and the results are easy to tamper with, particularly in urine tests which ideally would involve supervised specimen collection. He concludes, “Mandatory laboratory testing is not the best way to detect and treat illicit drug use in adolescents.”

However, a number of experts have chimed in on the opposite side of the issue, stating that drug testing is the best way to tackle a dangerous public health issue and protect teens against the vicious cycle of addiction.

Don Stewart, superintendent of Penn Manor School District in Lancaster County, Penn., believes in the value of drug testing “because it says we are willing to do all we can to prevent kids from throwing away their lives with drug use.”

Proponents of drug testing argue that the prospect of random drug tests is enough to deter some young people from using drugs, and provides teens with a valid excuse for refusing drugs when faced with peer pressure. They argue drug testing has been successful for decades in the U.S. Military, the federal government, and a number of Fortune 500 companies, and will be a useful tool for teens who need help to stay away from drugs.

Since the U.S. Military began drug testing in the early 1980s, drug use among its members has fallen almost 25 percent. The same result may hold true for schools, as suggested in a study published in the Journal of Adolescent Health, which reported that a school in Oregon that randomly drug tested student athletes had a 25-percent lower rate of drug use than comparable schools with no drug testing policy.

Some argue that drug testing sets clear rules and boundaries that teens need in order to know what is expected of them. Even without firm evidence that drug testing deters use, many people are in favor of taking every possible precaution to protect our kids.

Ways Teens Cheat

Today’s teens are clever, and when it comes to drug use, where there’s a will, there’s a way. For the tech-savvy teen, information on ways to beat drug tests is readily available on the Internet, with dozens of companies marketing products and pointers specifically geared toward passing the tests. The following are the top five ways substance-using teens beat the common urine test:

  1. Diluting the urine by adding water to the urine specimen, or by drinking large amounts of water to over-hydrate themselves.
  2. Substituting urine from another source, such as a friend or even commercially available urine.
  3. Using commercial “screens” like QuickKlean, Goldenseal, or Super Clean 13 to dilute a sample.
  4. Drinking vinegar to alter the pH balance in urine.
  5. Adding substances like salt, soap, or eye drops to the urine.

Despite all of these efforts to cheat the system, there are a number of counter-measures parents, schools, and employers are taking to detect doctored results. But even with these counter-measures, parents have to keep in mind that drug tests are not 100 percent accurate. If you choose to test your teen, any positive screen should be followed by a laboratory-based test to confirm or disprove the results. Moreover, parents should carefully convey the intent and purpose behind testing – the care you have for your child’s health and well-being.