The investigation by the Federal Institute for Risk Assessment (BfR) in Berlin found two thirds of espresso machines tested released high levels of lead after undergoing regular cleaning for limescale, Spiegel reported.
Researchers measured the concentrations of lead in water going through the machine immediately after cleaning at up to 100 times the limits recommended by the EU.
Even secondary tests several days later revealed lead content was still up to five times higher than the European benchmark.
The study found strong cleaning materials used to clear calcium deposits were coming into contact with machine parts which released large amounts of lead into the system – and into people's drinks.
The BfR said the study's discoveries were a real health risk requiring action. "The lead emissions need to be minimized to guarantee users' safety," a spokesman told Spiegel.
The study was conducted on plumbed-in, pump driven espresso machines of the type used in many coffee shops.
"Capsule" or "coffee pod" type machines for the home market release only minimal traces of lead, Spiegel said.