During transportation, delivery, commercial distribution and warehousing in cooled, refrigerated or frozen conditions the bacteria growth conies to a standstill, but subsequent use or application will enable the bacteria to cause renewed growth under favourable temperatures and conditions. Salmonella bacteria...
But to launder money you have to buy the metal and I'm sure anyone taking delivery on large amounts of metal would be suspect, especially because they would be paying cash. Depends how drug users fund their habit. If it is through burglary then they may find paying for drugs with stolen...