In the deadly attacks in Brussels this week, the terrorists reportedly used the explosive triacetone triperoxide (TATP). Anyone with basic chemistry knowledge and access to ingredients available at the average drugstore can make this substance.

In fact, TATP can be created using acetone and hydrogen peroxide, two chemicals commonly found at the typical local drugstore. Acetone, the simplest ketone, is the main component of nail polish remover, and hydrogen peroxide is used for bleaching hair and disinfecting surfaces and wounds.

These simple materials create an effective and hard-to-detect explosive. TATP is roughly 80% as powerful as trinitrotoluene (TNT) and, unlike most explosives, does not contain nitrogen, allowing it to evade conventional methods of detecting explosives.

TATP was not only used in the Brussels attacks but also in the attacks on Paris last year, where it powered seven of the eight suicide vests used. But what is most notable about the Brussels attacks was the quantity of TATP discovered after the bombings.

Belgian authorities reported finding 33 pounds of TATP in the attackers’ residence. Basic stoichiometry reveals that such an amount of TATP would require approximately 15.4 liters of nail polish remover and 6.9 liters of hydrogen peroxide to manufacture (at commercially available concentrations – pure acetone and three percent peroxide.)

What is alarming is that the attackers could even purchase such large quantities of reagents without raising suspicion. Nobody buys 31 bottles of nail polish remover in such a short amount of time. Most would not need as much acetone in a lifetime.

Derek Yen

As a result, there is a simple way to prevent the mass manufacture of such deadly explosives: regulate the amount of acetone and hydrogen peroxide that citizens are allowed to buy.

Like purchasing tobacco or alcohol, customers should be required to present an ID when purchasing these products. Then, purchase history would be monitored through a government database, allowing law enforcement to identify potential threats who exceed a maximum allotted purchase in a given time frame.

A similar policy has been proposed in Congress before, though for different reason; this bill restricting the sale of cough syrups and other over-the-counter medications which contain dextromethorphan (DXM) to minors due to DXM’s potential for drug abuse was introduced in 2015. Though such a proposal has yet to turn into federal law, several states – including California – have already implemented versions of this policy.

While it may initially seem silly for nail polish remover purchases to be federally regulated, this measure could help prevent future terrorist attacks by severely hindering terrorists’ ability to construct powerful but hidden explosives.

Furthermore, these regulations wouldn’t significantly impact the average citizen. I don’t know many people who would ever need to buy 31 bottles of nail polish remover in a short period of time.

I am not proposing that the government be able to record all purchases made by citizens – only those of certain regulated chemicals. This question is similar to the one debated in the recent case between Apple and the FBI – how much can a citizen’s privacy be intruded upon in the name of national security?

In the piece that we ran on the topic, I defended Apple’s decision not to decrypt the San Bernardino shooter’s iPhone. While my two stances may initially appear contradictory, they are reconcilable.

There is a profound amount of private information that is stored in your iPhone. And there is a great potential for disastrous fallout if Apple were to comply.

But the strategy I am proposing to combat the creation of large-scale improvised explosives would only involve government interference in the case of questionably superfluous purchases of certain substances.

The risks to this suggestion are nearly nonexistent. The government will typically just learn who paints nails regularly and who prefers hydrogen peroxide over rubbing alcohol. As such, we cannot expect tremendous safety issues introduced by implementing this policy – hackers are probably not going to break into government servers to discover how much nail polish remover you’ve bought this month.

The back-end nature of this solution means that most people will never realize that these chemical purchase quotas exist. However, the vastly increased security resulting from this simple measure will not go unnoticed.