Law enforcement and correction officers use field tests to discern the presence of illicit drugs. They're not just unreliable, they're dangerous.

When police officers at a traffic stop or prison guards in a mail room think they've found illegal drugs, they reach for one thing. A presumptive field test.

These tests take the form of small, handheld pouches that contain glass ampules of chemicals. A sample is added to the pouch and the ampules are broken to allow the reaction to take place.

They're known to be unreliable: reports regularly detail rampant false positive results.

The latest was published in Massachusetts in 2021, where a class action lawsuit is seeking to prevent the state's prison system from using the tests, purchased from a company called Sirchie, on incarcerated people's legal mail.

In addition to being unreliable, presumptive field tests are potentially dangerous. They contain harsh chemicals that can cause severe burns and be toxic if inhaled.

"Every narcotics offer we talk to has either cut their fingers using a NIK test or knows a colleague who has," an alternative field test company spokesperson told the International Association of Chiefs of Police. NIK is another field test manufacturer whose tests are similar to Sirchie's.

These are the field tests Sirchie manufactures and sells to states like Massachusetts.

They all contain chemicals deemed hazardous to humans by the United Nations.

Three quarters of them contain concentrations high enough for contact with them to be acutely harmful.

The contents of most of those tests cause "severe skin burns and eye damage," according to the UN's classification system.

A quarter of the tests are classified as "toxic if inhaled."

This test, which looks for synthetic cannabis, is at the center of the Massachusetts lawsuit.

It's almost 50% sulfuric acid.

Like other tests that contain the acid, it's in the "sever burns" category.

In December 2021, a federal judge ordered the state's prisons to stop punishing incarcerated people based on positives from Sirchie tests, calling them "marginally better than a coin flip."

The state continues to use other Sirchie tests, spending just under $25,000 on them, at about $2 per test, in 2023.

The hidden dangers of presumptive drug tests