Cause for Concern

Experts Warn Against Letting Children Swallow Reagent Used in Home COVID Test Kits

Rapid COVID-19 diagnostic tests manufactured for home use – millions of which are now being distributed for free by the federal government – are playing an important role in helping to contain the coronavirus pandemic.

But some brands of tests use a reagent – a chemical that strips the virus of its DNA – that is potentially toxic if ingested by children, prompting cautions that people should use the tests exactly as indicated and keep them out of the hands of youngsters.

The problem, spotlighted in a paper published this week in the American Journal of Emergency Medicine, does not mean people should avoid home COVID tests.

“The message is just be careful with these reagents,” says Susan Smolinske, PharmD, director of the New Mexico Poison & Drug Information Center, who wrote the paper with and two colleagues from the National Capital Poison Center in Washington, D.C.

“We were getting a lot of requests for potential exposures to these home health tests,” says Smolinske, who is also a professor of Pharmacy Practice and Administrative Sciences in The University of New Mexico College of Pharmacy. “One of the colleagues and I spent a week calling every manufacturer who made these to find out what was in them.”

The chemical in question – sodium azide – is water soluble, odorless and colorless – and commonly used as a reagent in laboratories (it also is used in automobile airbags). In the test kits it separates out the viral DNA for analysis. But it also has toxic properties, and if it is ingested in sufficient concentration, it can cause a sudden drop in blood pressure.

“It’s transient,” Smolinske says. “It may last 10 or 15 minutes, but it could be enough to cause you to pass out while you’re driving a car or hit your head on something.”

Four of the popular home COVID test kits use sodium azide as a reagent, she says. It’s typically contained in small plastic vials, although in the case of one test it’s contained in a tube that looks like an eye dropper – and some people have mistakenly put it in their eyes, Smolinske says.

But there is reassuring news. “The volume in these little vials is very small,” she says. And the solution is in a low enough concentration that it’s unlikely to affect an adult, even if swallowed. But children, with their smaller body weight, are more vulnerable.

We don’t think it poses a risk at all with oral ingestion for an adult, but with kids it does

— Susan Smolinske, PharmD