Ines Vuckovic / Dose

But you’ve probably never even tasted it.

What do wiper fluid, air freshener, surface cleaner and fabric softener all have in common? Besides keeping your stuff fresh and clean, they also all contain one ingredient that boasts the most bitter taste in the world. So bitter in fact, official U.S. Army reports say it could be used in chemical warfare efforts to render enemy food supplies unfit for human consumption.

This vile ingredient is Denatonium Benzoate, more commonly known as Bitrex. And according to the Guinness Book of World Records, it’s the most bitter substance in the world. One taste tester described it as “like a place where old spiders go to die.”

If you don’t believe me, you can watch these advocates do a taste test or even request your own.

The substance was accidentally created by scientists in 1958, while working on a new formula for a local anesthetic. It was quickly rejected as an anesthetic and repurposed to make dangerous products even less appealing for consumption.

Just one molecule of Bitrex can make a million molecules of water undrinkable and when added to household products—it’s intended to make children spit it out before swallowing.

In the early 1980s, when accidental ingestion of poison was becoming a serious widespread problem, concerned mother Lynn Tylczak started an awareness campaign about the benefits of adding Bitrex to dangerous household products.

After hearing how European manufacturers were finding great success with adding Bitrex, she started a letter-writing campaign to promote its use in the US. Tylczak collected a group of like-minded friends and contacted numerous media outlets until their efforts caught the eye of local politicians and national advocates who had the power to make real changes.

Bitrex

In 1995, an Oregon law was passed requiring antifreeze to include the chemical. And while there is no national law requiring the use of Bitrex in effect today, it is regularly added to thousands of products from perfumes and household cleaners to home improvement products and children’s toys.

Any product with Bitrex added will display a descriptive logo—you’ll likely be surprised to find it all over the grocery store—and it’s widely used in 60 countries.

Toy Bitrex

Note: Bitrex itself is completely harmless if ingested, but this will not be the case for the product it is added to. Bitrex should not replace common-sense efforts to prevent accidental poisoning.