Police dogs have to stay away from ATMs and banks lest their noses explode.
About the only currency not contaminated with drug residue is direct from the Bureau of Engraving and Printing. Once it gets stuck in a wallet or cash drawer it starts picking up enough drug residue to detect.
Actually, it gets it at the Federal Reserve bank, while passing through their counting machines. Someone a few years back tested brand new bills direct from an FR bank, and it tested positive.
The U.S. Government is a criminal enterprise.