Kansas' Flawed DUI Drug Screen isn't Better Than Nothing; It's Worse

The Kansas Highway Patrol is using a new device called SoToxa, which is marketed by Abbott, to help detect people who are driving while high on drugs. The device, which tests saliva from a person’s mouth, will be used to tell troopers what drugs might be in their system. On the surface, maybe this sounds good, but the obvious question is: After a drug of potential abuse is detected, then what?

This is not a rhetorical question. Although the test can accurately identify members of six drug classes (more on this later) in saliva this may have little or nothing to do with whether a driver is impaired. Why? A comparison of SoToxa with the alcohol breathalyzer is informative. Upon first glance, the two tests may appear functionally similar but they are anything but. 

A breathalyzer test provides a quantitative measure of alcohol levels in the breath and this number can be correlated with the blood concentration and the degree of the driver's impairment. But the SoToxa test only gives yes or no answers – whether the drug is present at the level of detection of the device. It cannot measure the dose or exposure. And even if it could, as a blood test can, there are no standards to determine what levels of different drugs cause impairment (1).

It's a bit ironic that the new SoToxa technology actually violates very old technology invented five centuries ago by Theophrastus von Hohenheim, better known as Paracelsus: "The dose makes the poison." The readout from a single oxycodone tablet taken for a dental procedure from the day before will be indistinguishable from five pills at a party that same night. The same goes for the other drugs that are detected by the test. This is the Achilles Heel of the test. Anyone who reads ACSH articles regularly will already know that the presence of a chemical, even a toxic chemical, does not mean that it is causing any harm. Similarly, the presence of a drug does not determine whether the driver is impaired or not. 

How impaired is impaired?

The Abbott promotional literature cites one reference, a 2015 survey published by the US National Highway Traffic Safety Administration. The document discusses the limitations of drug testing; the message could not be clearer: [my emphasis]

The reader is cautioned that drug presence does not necessarily imply impairment. For many drug substances, drug presence can be detected after impairment that might affect driving has passed... Whereas the impairment effects for various concentration levels of alcohol in the blood or breath are well understood, there is little evidence available to link concentrations of other drugs to driver performance.

Moreover, SoToxa measures drugs at or above the limit of detection of the instrument. Suffice it to say that this doesn't address the degree of impairment, only the sensitivity of the device. So, what SoToxa is really measuring is whether drugs are present at a concentration that the device can measure. And if another more sensitive instrument is marketed will those numbers be used instead?

Drugs and metabolites measured by SoToxa as well as the limit of detection for each compound. These values have little or nothing to do with the degree of impairment of the driver. Source: Abbott

More problems still

It should be obvious that SoToxa isn't simply targeting recreational drugs, like alcohol, which can be avoided before driving. Of the six classes of drugs, three (maybe four, if you count THC) are commonly prescribed legal prescription drugs. People take them for extended periods of time.

Approximately one percent of US adults have been diagnosed with ADHD, some of whom will be taking a drug like Adderall (amphetamine), possibly on a long-term basis. About 30 million people take a prescribed benzodiazepine (like Valium), typically for anxiety, as well as chronic pain patients who take prescription opioids. Anyone who is taking medications in these three classes – millions of people – whether impaired or not, will "fail" SoToxa simply for following their doctor's orders.

It might even be worse

State Trooper Sean Hawkins told KWCH (Wichita) News: 

We’re checking for amphetamines, methamphetamines, cocaine. We’re also checking for tetrahydrocannabinol, the active ingredient in marijuana that makes people high. We’re checking for some opiates and some benzodiazepines, some of those mood stabilizers..."

Mood stabilizers? Which ones? There are a number of them in different classes used primarily to help with bipolar disorder and also depression. Ironically, one drug that is sometimes used is Neurontin, which is being shoveled down patients' throats (even though it doesn't work) as a faux substitute for opioids. So perhaps you can add people with bipolar disorder to the list of SoToxa failures.

Don't worry. The government won't use this against you. Or maybe it will.

According to KWCH:

Results from SoToxa devices are not allowed to be used in court proceedings and are only part of an impaired driving investigation. They are also not used to randomly test drivers. Drivers must have other signs of impairment.

Forgive my cynicism but when it comes to drug policy I don't trust either the intelligence or integrity of any agency that might be involved. My take on this? "Results from SoToxa devices are not allowed to be used in court proceedings now" is probably more accurate. Paranoid? I think not. After all, we went from opioid "Guidelines" in 2016 to the DEA targeting pain management physicians for daring to write scripts greater than what the agency in all of its wisdom, deems appropriate. No, I don't think for a second that these tests won't be used against drivers sometime down the road.

By legalizing marijuana states have guaranteed that more impaired drivers will be on the road. This is a serious problem, but a simple and scientifically inadequate solution isn't the way to control this. In the absence of a reliable method to test whether bad driving is caused by drug impairment implementing this mess will be worse than nothing.

NOTES

(1) This issue has been discussed for THC. "Individuals react to tetrahydrocannabinol, the active ingredient in marijuana, in different ways, making it nearly impossible to set legal limits that estimate a roughly equal level of driving impairment. Some people drive without measurable impairment while others are incapacitated with the same amount of THC in their blood." Joel Shurkin, Inside Science (2019)