Hydrogen peroxide and acetone are used to make triacetone triperoxide, or TATP, a powerful explosive with the consistency of granulated sugar used by operatives in their attacks against Paris and Brussels. The bombers who killed 52 in London in 2005 used it, and al Qaeda operative Richard Reid stuffed it in his shoes in a failed attempt to bring down an airliner flying from the U.K. to the U.S. in 2001.
Ehud Keinan, an Israeli chemist and one of the world’s leading authorities on TATP, said the explosive can be made with minimal technical skill and household equipment. “You can start in the evening, and in the morning it will be ready,” Mr. Keinan said.
The EU’s regulatory system, among the strictest in the world, depends on businesses reporting suspicious transactions of hydrogen peroxide, acetone and a number of other chemicals to the police. Businesses are urged to look for a number of red flags, such as if the customer’s use for the chemical is unclear or the purchase is made using large amounts of cash. The rules also ban consumers from owning seven potentially dangerous chemical solutions, including hydrogen peroxide solution, in concentrations higher than 12%.
But the fact that the chemicals have so many commercial applications—from disinfecting pools to removing nail polish—makes identifying suspicious transactions challenging. Authorities and experts say the huge quantity of legitimate trade of such widely-used chemicals means finding suspicious transactions is effectively like picking a needle out of a haystack.
“It’s a very difficult area because there are thousands of legitimate uses for these substances,” said Peter Newport, chief executive of the Chemical Business Association, which represents U.K. chemical distributors.
Some officials have also expressed worries that not all of the 28 EU governments have swiftly implemented the regulations, failing, for example, to create a contact point in law enforcement that would investigate suspicious transactions.
It remains unclear how the Islamic State operatives obtained the chemicals. An official with the Belgian Association of Chemical Distributors wasn’t aware of any suspicious transactions reported to the police in recent months. A Belgian police spokesman declined to comment.
The monitoring program used by customs agencies, called Global Shield, was sought by U.S. authorities seeking to stop the flow of bomb-making chemicals into Afghanistan, where insurgents used them to build bombs that were killing U.S. troops. These chemicals were mainly ammonium-nitrate fertilizer or potassium chlorate shipped from China for use in Pakistan’s match industry and then smuggled across the border.
Now shipments of these chemicals crisscrossing the globe are monitored through a system maintained at the World Customs Organization in Brussels. Customs agencies are supposed to warn each other about suspicious shipments, using some of the same criteria identified in the European regulations.
TATP poses a particularly serious threat to aviation, says Mr. Keinan. The chemical isn’t detectable, he says, by the machines installed at many airports, which are able to uncover more common, nitrogen-based explosives such as TNT. Dogs can also be trained to detect the material.