Guest Post by ToxiFox
Welfare Drug Testing
I very rarely argue with or try to school people on social media. It seems like a fairly futile activity, and I really prefer to look videos of cute baby bats being bottle fed (seriously, they are fucking adorable). That said, there is one issue that really raises my ire and will goad me into playing the angry devil’s advocate.
That issue is drug testing people who apply for welfare benefits.
Others have made the arguments against this practice for moral and legal reasons far better than I could.
Why Drug Testing Welfare Recipients Is a Waste of Taxpayer Money
I have seen nothing though that addresses scientific shortcomings of large scale drug testing as applied to this purpose. I will give some examples on analytical issues for the Federal Five: THC, cocaine, amphetamines, opiates, and PCP, that I hope will illustrate why I think this testing is a bad idea.
Drug testing is typically a two tiered process. Everyone receives an initial immunoassay screen. This can be a cup, a dipstick, or an actual clinical chemistry analyzer. They all work by the same general principle. The test has antibodies that will react with molecules having certain structural characteristics. If a molecule with the right kind of structure is there, the antibody will bind to it and you will have a positive result. If a molecule that the antibodies can bind to is not in a sample, no positive result. Seems pretty straightforward, right?
Well… notice I said that the antibodies bind to molecules having certain “structural characteristics”. These characteristics are not unique to illicit drugs. Some immunoassays, such as those for amphetamines, can have false positive rates as high as 10%. These tests are notorious for their low specificity for amphetamines due to the fact that structurally, amphetamines are pretty generic looking compounds.
False positive results for illicit amphetamines have been seen for Wellbutrin (an antidepressant), Thorazine (an antipsychotic), DMAA (a compound found in dietary supplements), Labetalol (a drug for high blood pressure), Ephedrine (sometimes used in pregnant women to assist in labor/delivery), Metformin (a drug for diabetes), and Trazodone (an antidepressant often used off-label for insomnia). [Adapted from Saitman et al. “False-Positive Interferences of Common Urine Drug Screen Immunoassays: A Review” Journal of Analytical Toxicology 2014; 38: 387-396].
You can see from these examples that a pretty wide swath of people could be taking one or more of these drugs, and this is not anywhere near to being a comprehensive list of the compounds that can cause false positive results in amphetamines tests.
What about a compound with a more complicated structure though?
Let’s take THC as an example. Some screening tests will give a positive result for THC in the presence of the non-steroidal anti-inflammatory drugs Ibuprofen and Naproxen. Yes, that’s right, your friendly over-the-counter pain reliever can potentially make you look like a total stoner. There was even a paper published detailing four different commercial baby soaps that could cause false positive THC results (Cotten et al. “Unexpected Interference of Baby Wash Products with a Cannabinoid (THC) Immunoassay” Clinical Biochemistry, 45, 605-609). Imagine being a new mom in desperate need of assistance and your fucking baby soap makes you screen positive for pot.
Opiates present a whole host of problems that aren’t related solely to drug testing. A very large number of people are on legally prescribed opiate treatment for chronic pain. Are these people going to get refused benefits because of a legal prescription (which could also be an issue with amphetamine and THC)? Well, just provide proof of a prescription! Ok, but how do we weed out those who are actually taking heroin versus legally prescribed morphine (the human body turns heroin into morphine within about 24 hours)? What about people who are prescribed one opiate but are taking an extra one illegally? Opiates are compounds that have complicated, interrelated metabolic pathways. Even pain management doctors and pharmacists caring for these patients often don’t fully understand the metabolism of these compounds and have a difficult time interpreting the results of drug tests. Sometimes even highly specialized drug testing can’t give a definitive answer as to what a person actually took.
In addition to these issues, drug screens for opiates are also susceptible to false positive results. Quinolone antibiotics, the antipsychotic Seroquel, and the antihypertensive drug Verapamil have all been documented as causing false positives for opiates (Saitman et al.). Poppy seeds are also known to cause false positive results. If anyone ever tells you that’s an old wives’ tale, it’s not. I did the experiment myself because I fucking love poppy seed bagels, and I was bored at the lab one day. I would have tested positive for heroin.
PCP is a drug that has managed to stay on the Federal Five even though hardly anyone uses it anymore. I can honestly say I’ve seen far more false positives for PCP than I have true results. When we actually see a true positive, it’s a remarkable event. Unfortunately, a common antidepressant, Effexor, has been shown to cause false positives in some screening tests (Sena et al., “False-Positive Phencyclidine Immunoassay Results by Venlafaxine and O-Desmethylvenlafaxine”, Clinical Chemistry 2002, 48 (4); 676-677).
Cocaine screening tests are actually quite good. If your screen comes up positive for cocaine, you probably did cocaine.
How do we deal with these false positive results?
That’s where the second tier of testing comes in. Positive results are reflexed to a more specific and sensitive test (called a confirmation test), generally either gas or liquid chromatography coupled to mass spectrometry. Some people might ask, “why not use this test all the time if the screens are so bad?” These tests are a lot more complicated to do. They take more time, highly skilled technicians, expensive equipment, and are consequently much more expensive to run.
Does the state pay for and run these confirmation tests or is the potential welfare recipient responsible for locating a laboratory to run the confirmation test and paying for it? Either option has drawbacks. The state option would cost taxpayers yet more money and would likely not be done in the timeliest manner (if the current state of forensic toxicology testing is any indicator). The potential welfare recipient may not know how to find a confirmatory laboratory, and in the event that they do, the test could be prohibitively expensive, especially for someone who needs welfare assistance.
These reasons, together with the moral and legal arguments, make me overwhelmingly against drug testing people for welfare benefits. The states that have actually instituted the testing are seeing extremely low rates of positive results, indicating that just because you’re poor, you aren’t necessarily taking drugs. You probably can’t fucking afford them.
And for anyone interested in the really cute baby bats: