Library books could come with a side of germs | Science News for Students

Library books could come with a side of germs

A bookworm did an experiment to discover how many bacteria build up on books
May 18, 2017 — 6:50 am EST
library books

Could library books be hiding bacteria? A teen did an experiment to find out.


LOS ANGELES, Calif., — There’s a lot to love about libraries. But could those thousands of free books be harboring bacteria? Cheyenne Deibert, 16, created a science fair project to find out. Her results will make book lovers heave a sigh of relief — most tomes are perfectly clear. She also showed that when it comes to microbes, it’s not how many times a book gets checked out, it’s how recently that book has been handled.

The sophomore at Clarksville Academy in Tennessee brought her results here, to the Intel International Science and Engineering Fair (ISEF). Created by Society for Science & the Public and sponsored by Intel, the competition this year brought together nearly 1,800 students from more than 75 countries to show off their winning science fair projects. (The Society also publishes Science News for Students and this blog).

Cheyenne admits she’s a real bookworm. But reading while home sick, she began to see her books in a different light. “If I’m reading these while I’m sick, there’s bacteria all over,” she recalls thinking. “I’m touching these library books, passing them from person to person. Do they have bacteria?” She knew that germs could end up on items that are handled frequently, such as money. The teen decided to test her suspicions that books may too. And she did it with an experiment.

Cheyenne Deibert and her project
Cheyenne presents her germy project at Intel ISEF.
Chris Ayers Photography/SSP

With the help of local librarians, the teen collected 12 books that had been published on or after August 1, 2016. They included Amy Schumer’s The Girl with the Lower Back Tattoo, Mary Roach’s Grunt: The Curious Science of Humans at War and Beth Harbison’s Show Addicts Anonymous. The teen aimed for books that were about the same size and could be found in the “popular” section. She wanted "books people would actually read [and touch a lot], as opposed to looking at page 300 for a reference,” she explains.

She sorted the books by how often they had been checked out — zero, one, two and three times. Cheyenne hypothesized that books that were checked out more often would host more bacteria.

The teen carefully swabbed the first page of the first chapter of each book as well as the blank page opposite to it. She then rubbed her swabs on four petri dishes per book. Two of the petri dishes contained only agar — a gellike substance many bacteria like to eat. The other half contained agar with methylene blue. This chemical inhibits the growth of some species of bacteria but encourages others. It helped Cheyenne determine if certain species that might be harmful were present, such as E. coli.  

To keep the dishes near body temperature (around 37° Celsius or 98.6° Fahrenheit), Cheyenne put them in an oven for 47 hours. Then she took the plates out and counted how many bacterial colonies she could see.

Of the 12 books, seven grew no bacteria at all. With the five that did grow germs, the teen found that her hypothesis had not been right: The number of times a book had been checked out didn’t seem to affect how many microbes were present. 

What she found

Cheyenne looked at the number of days between when a book had last been returned to the library and when she started her experiment. Those sitting in the library for only three days tended to have more bacteria than those that had last been returned 20 days before her tests, the teen found. This makes sense, she notes. If a book is sitting around untouched, the bacteria in its pages might die off. And with no new readers, new bacteria are not being added. But if the tome had been checked out recently, microbes might still be hanging out.

Overall, not many microbes showed up on the books she tested. None of the swabs transferred E. coli to the dishes. The teen compared her findings to results from scientific papers on library-book bacteria. The authors of those papers found bacteria and fungi on library books, and some of those germs might be resistant to antibiotic drugs. But like Cheyenne, they didn’t find high levels of microbes. They also concluded that fungi (such as molds) were probably more worrisome than bacteria. Mold can be harmful for people with lung problems such as asthma and cause disease in people with weak immune systems.

That’s not the end of Cheyenne’s investigations. The teen now would like to look into how long bacteria from someone’s hand might survive on a book's pages, and if there are more microbes at different times of year.

For now, her data indicate, librarians (and book lovers) don’t have much to worry about. Cheyenne notes, however, that she does wash her hands after reading. Just in case.

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Power Words

(more about Power Words)

agar     A gelatinous material made from certain marine algae used as a material (and food source) in which to grow bacteria.

asthma  A disease affecting the body’s airways, which are the tubes through which animals breathe. Asthma obstructs these airways through swelling, the production of too much mucus or a tightening of the tubes. As a result, the body can expand to breathe in air, but loses the ability to exhale appropriately. The most common cause of asthma is an allergy. Asthma is a leading cause of hospitalization and the top chronic disease responsible for kids missing school.

bacteria     ( singular: bacterium ) Single-celled organisms. These dwell nearly everywhere on Earth, from the bottom of the sea to inside other living organisms (such as plants and animals).

bacterial     Having to do with bacteria, single-celled organisms. These dwell nearly everywhere on Earth, from the bottom of the sea to inside animals.

blog     Short for web log, these Internet posts can take the form of news reports, topical discussions, opinionated rants, diaries or photo galleries.

chemical     A substance formed from two or more atoms that unite (bond) in a fixed proportion and structure. For example, water is a chemical made when two hydrogen atoms bond to one oxygen atom. Its chemical formula is H2O. Chemical also can be an adjective to describe properties of materials that are the result of various reactions between different compounds.

E. coli     (short for Escherichia coli) A common bacterium that researchers often harness to study genetics. Some naturally occurring strains of this microbe cause disease, but many others do not.

engineering     The field of research that uses math and science to solve practical problems.

fungus     (plural: fungi) One of a group of single- or multiple-celled organisms that reproduce via spores and feed on living or decaying organic matter. Examples include mold, yeasts and mushrooms.

hypothesis     (v. hypothesize) A proposed explanation for a phenomenon. In science, a hypothesis is an idea that must be rigorously tested before it is accepted or rejected.

immune   Able to ward off a particular infection. Alternatively, this term can be used to mean an organism shows no impacts from exposure to a particular poison or process. More generally, the term may signal that something cannot be hurt by a particular drug, disease or chemical.

immune system  The collection of cells and their responses that help the body fight off infections and deal with foreign substances that may provoke allergies.

Intel International Science and Engineering Fair     Or Intel ISEF. Initially launched in 1950, this competition is one of three created (and still run) by the Society for Science & the Public. Each year, approximately 1,800 high school students from more than 75 countries, regions, and territories are awarded the opportunity to showcase their independent research at Intel ISEF and compete for an average $4 million in prizes. 

microbe     Short for microorganism. A living thing that is too small to see with the unaided eye, including bacteria, some fungi and many other organisms such as amoebas. Most consist of a single cell.

petri dish    A shallow, circular dish used to grow bacteria or other microorganisms.

plastic     Any of a series of materials that are easily deformable; or synthetic materials that have been made from polymers (long strings of some building-block molecule) that tend to be lightweight, inexpensive and resistant to degradation.

Society for Science & the Public  A nonprofit organization created in 1921 and based in Washington, D.C. Since its founding, SSP has been not only promoting public engagement in scientific research but also the public understanding of science. It created and continues to run three renowned science competitions: the Regeneron Science Talent Search (begun in 1942), the Intel International Science and Engineering Fair (initially launched in 1950) and Broadcom MASTERS (created in 2010). SSP also publishes award-winning journalism: in Science News (launched in 1922) and Science News for Students (created in 2003). Those magazines also host a series of blogs (including Eureka! Lab).


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