The use of paper money has an intricate relationship with drugs. The first 10 Dollar bill produced by the Federal Reserve Bank in the United States was printed on cannabis hemp fibre that soon would become illegal and production moved to cotton. Almost all paper money in circulation has been found to have traces of cocaine powder, meaning that technically everyone carries a small amount of illegal drugs in their wallet.
It would not be until 2018 that hemp production became legal again in the United States. 25 grams is considered to be personal possession in Portugal.