People in different countries use different types of 1 yuan in China, pesos in Mexico, pounds in the United Kingdom, dollars in the United States, Australia and New Zealand. They may use 2 currencies, but these countries, and probably all countries, still have one thing in common1: Germs on the banknotes. Scientists have been studying the germs on money for well over2 100 years. At the turn of the 20th 3 , some researchers began to suspect that germs living on money could spread disease. 4 c/ l, ^. P( V! r( ~
Most studies of germy money have looked at the germs on the currency 4 one country. In a new study, Frank Vriesekoop3 and other researchers compared the germ populations found on bills of different 5 .
! r+ f' t8 z* E$ F9 R8 s! p Vriesekoop3 is a microbiologist at the University of Ballarat in Australia4. He led the study, which compared the germ populations found on money 6 from 10 nations. The scientists studied 1,280 banknotes in total; all came from places where people buy food, like supermarkets street vendors and cafes, 7 those businesses often rely on cash.
% {0 y4 [- Z ]9 j6 s Overall, the Australian dollars hosted the fewest live bacteria ---- no more than 10 per square centimeter. Chinese yuan had the most ---- about 100 per square centimeter. Most of the germs on money probably would not cause harm. # F g+ S8 ~$ A! I4 l) V' u4 a
What we call "paper" money usually isn’t made from paper. The U. S. dollar, for example, is printed on fabric that is mostly 8 .Different countries may use different 9 to print their money. Some of the currencies studied by Vriesekoop and his 10 such as the American dollar were made from cotton. Others were made from polymers. ! I5 ~6 C% G' Y' d8 f* w8 ]( W
The three 11 with the lowest numbers of bacteria were all printed on polymers. They included the Australian dollar, the New Zealand dollar and some Mexican pesos. F; ]7 {& e* ~% \( h4 i
The other currencies were printed on fabric made 12 of cotton. Fewer germs lived on the polymer notes. This connection suggests that 13 have a harder time staying alive on polymer surfaces. Scientists need to do more studies to understand how germs live on money-----and whether or not we need to be concerned. Vnesekoop is now starting a study that will 14 the amounts of time bacteria can stay alive on different types of bills. . Y" H4 V2 J* W! M
Whatever Vriesekoop finds, the fact remains: Paper money harbors germs We should wash our 15 after touching it; after all5, you never know where your money ’s been. Or what’s living on it. |