Whenever the subject of money comes up, there's a party bore waiting in the wings to tell us that physical tender is filthy, covered in skin and drugs and particles of anus. But a new study of the recently-introduced polymer £5 notes shows that while they are indeed festooned with "colony-forming units" of bacteria, they're mostly the good kind - harmless or perhaps even beneficial to humans.
The study - carried out by Wickham Laboratories - involved first sanitising the notes, then simulating normal conditions (keeping them in a pocket or wallet, and exchanging them the average amount of times over two weeks in realistic environments), before analysing the "bioburden" (aka gross tiny things) on each note.
The results showed that while levels of bacteria varied considerably (between 31 and 4600 colony-forming units per note), the bacteria found was all Gram-positive (meaning it absorbs the dye in a Gram stain test) - that's not in itself a good thing, but most disease-causing bacteria is Gram-negative, and the specific types of bacteria found were benign. As Medical Plastics News reports:
"Two of the most common bacteria found on the notes were organisms regularly found in soil, dust, water and air. The most common bacteria, micrococcus luteus, is also a normal bacterium of human skin.
Thankfully there was no indication of faecal organisms or ‘coliforms’ on the notes, perhaps indicating that those handling them had good hygiene or that the polymer note doesn’t provide favourable conditions for this group of bacteria to survive."
Hear that? Despite the word "SPECIMEN" across the photo up top, there's no poo on our polymer pounds.
When the new fivers were announced, we were promised that they'd be cleaner and more durable (in addition to the main benefit of being much harder to forge). It's good to hear that those claims were justified - especially given that certain tabloids insisted the plastic notes would provide a welcoming home for superbugs like E-coli and MRSA. We should have bet them a fiver. [Medical Plastics News]