Swiss scientists have found that 43kg of gold worth about $1.8 million is passing through Switzerland’s wastewater each year, as first spotted by Bloomberg. The gold is lost through sludge and effluent from the country’s waste treatment plants according to a report by scientists at the Swiss Federal Institute of Aquatic Science and Technology. On average, about 70 percent of the world’s gold passes through Swiss refineries.

The scientists noted that the concentrations found in the wastewater don’t pose risks to the environment, and wide-scale recovery wouldn’t be worthwhile. But, they did find that there were some sites where recovery of the gold could be viable, like in the refinery-rich Ticino region where concentrations of the precious metal were likely high enough to justify the extraction effort and cost.

In addition to gold, it also found 3,000kg of silver lost in the sludge each year — worth around $1.7 million — and concentrations of trace elements like tantalum and germanium often used in the technology and medical sectors. The study centered on 64 waste treatment plants across Switzerland and claims to the be the first systematic wastewater survey for trace elements in an industrialized country.