NSF Scrub Club

May 5, 2011

Greta Houlahan
NSF International
Phone: +1.734.913.5723

Kitchen is "Germiest" Place in Home, According to Recent Study by NSF International

Study reveals top 10 germ hot spots and dangers, NSF also provides cleaning tips to make the home a safer place

ANN ARBOR, MI - Findings from a study released today indicate that there are common misconceptions about where the highest concentration of germs are found in the home. NSF International, an independent public health and safety organization, conducted a swab analysis of 30 everyday household items in 22 different homes and found that the germiest place in the home is the kitchen, while many people perceive the bathroom to be the room with the most germs.

NSF International's "Germiest Places in the Home 2011" study was conducted in an effort to identify germ "hot spots" in the home. NSF microbiologists measured the levels of yeast, mold, coliform bacteria (a family of bacteria that includes Salmonella and E. coli and is an indicator of potential fecal contamination) and Staph bacteria. Surprisingly, the data showed that the germiest item in the kitchen - the germiest overall room in the house - was actually the sponge, ironically the item frequently used to clean dishes and countertops.

"Sponges pick up bacteria during the cleaning process and are typically not properly - or regularly - sanitized before their next use," explained Dr. Rob Donofrio, Director of Microbiology at NSF International and lead researcher for the study. "Additionally, sponges are often wet and left in damp areas in or near the sink, providing optimal conditions for germ growth. They also have many nooks and crannies which can be great places for germs to multiply."

The kitchen also was the area of the home in which coliform bacteria was most prevalent. In the homes tested, NSF found coliform on multiple kitchen surfaces, including dish sponges/rags (75 percent), kitchen sinks (45 percent), countertops (32 percent) and cutting boards (18 percent). The high coliform count on these surfaces is likely attributed to an individual's cleaning process. While these surfaces tend to be wiped-down regularly, NSF International's analysis indicates they typically are not being properly disinfected. Sources of coliform can be traced to many food items, including unwashed produce as well as raw meat and poultry. In addition, coliform can be introduced into a kitchen area through improperly washed hands and through contact with household pets, including pet dishes and toys. Coliform and Staph can both cause serious infections in individuals with a compromised immune system, as well as the very young, elderly and pregnant women.

Perhaps not as surprising, the NSF survey found the second germiest place in the home was the bathroom, where the toothbrush holder was identified as having the most germs.

"The high bacteria levels on and in the toothbrush holder are likely attributed to two causes. First, toothbrush holders are typically situated near the toilet, especially in smaller bathrooms. Flushing of the toilet causes aerosols, containing fecal bacteria, to land on items near the toilet, thereby potentially contaminating the holder," explained Dr. Donofrio. "Additionally, toothbrush holders often are neglected in the cleaning process, providing an ideal breeding ground for germs. Toothbrush holders should be regularly cleaned in the dishwasher."

Perception vs. Reality: What Families Thought Would Have Most Germs

Before conducting the swab analysis, NSF International asked a member of each volunteer household to rank the items they thought would have the most germs in their home. The survey revealed misconceptions about which household items had the most germs. Items found in the bathroom were most frequently ranked by survey respondents as being perceived to be the germiest items in the home; however the swab analysis revealed that kitchen items actually had higher germ counts than bathroom items. For example, kitchen items such as the coffee maker reservoirs, countertops and stove knobs actually had higher germ counts than bathroom items, such as the bathroom door knob and light switch.

Following is a list of what were perceived to be the germiest items in the home versus the actual germiest items (ranked from highest to lowest in germ count):

Volunteers Thought:

Actual Findings:

1.Toothbrush holder

1. Dish sponge/rag

2. Dish sponge/rag

2. Kitchen sink

3. Money

3. Toothbrush holder

4. Pet toy

4. Pet bowl

5. Kitchen counter top

5. Coffee maker reservoir

6. Bathroom door knob

6. Bathroom faucet handle

7. Kitchen sink

7. Pet toy

8. Pet bowl

8. Kitchen Counter top

9. Toilet handle

9. Stove knobs

10. Bathroom light switch

10. Cutting board

"We conducted this study to help identify where the germs are in the average person's home and - more importantly - help people understand how they can better protect themselves from bacteria, yeast and mold," explains Dr. Donofrio. "What's important to remember, though, is that germs exist everywhere - and that not all germs are 'bad.' A typical human body has been estimated to have more than 100 trillion bacteria, and as researchers, we know that bacteria is critical to our health in that it actually helps us fight off disease and chronic conditions. The key is to be smart about germs and bacteria - be aware of where the 'hot spots' are in your house and be smart about protecting your family. One of the ways you can help protect your family is to encourage consistent handwashing, which is why NSF developed an online learning tool called The Scrub Club to make handwashing fun for kids."

For tips on how to keep household items and surfaces clean, please visit the Germs in the Home section.

Household Germ Study Methodology: The NSF International "Germiest Places in the Home 2011" study was conducted by microbiologists at NSF International from December 2010 - January 2011. Thirty common household items in the homes of 22 volunteer families in the greater Ann Arbor, Mich. area were swabbed. The survey included items in the kitchen, bathroom as well as other personal items such as cell phones and purses for the presence of bacteria, yeast and mold.

About NSF International: NSF International, an independent, not-for-profit organization, certifies products and writes standards for food, water and consumer goods to minimize adverse health effects ( Founded in 1944, NSF is committed to protecting human health and safety worldwide and operates in more than 120 countries. NSF is a World Health Organization Collaborating Centre for Food and Water Safety and Indoor Environment.

Scrub Club® and Scrub Club characters are copyright 2007 NSF International.
"BAC" character copyright 2006 The Partnership for Food Safety Education.

Please distribute Scrub Club® materials freely in classrooms, publications, etc.,
provided that credit is given to NSF International.