The sponge and the sink are obvious culprits, but other everyday kitchen objects can harbor germs that cause foodborne illnesses — or worse.

Even the cleanest kitchen has germs.

When researchers from NSF International, a non-profit public health and safety organization, asked 20 families to swab 14 different kitchen items they found some surprising items were contaminated with various combinations of foodborne illness-causing germs such as E. Coli, Salmonella, Listeria and mold and yeast. This is a health hazard that's common in households across the country. 21 percent of cases of foodborne illness are actually due to food consumed in private homes, according to the U.S. Centers for Disease Control and Prevention. Here are some of the worst germ breeding grounds that are actually dirtier than a toilet seat!

Knife block

Be honest: when was the last time you cleaned this, if ever?

De-gunk it: Remove the knives, then turn the block upside down to shake out crumbs. (You can also use a can of compressed air, like a computer keyboard cleaner.) Wash the block in hot soapy water and get in the slots with a small brush, like the kind designed to clean baby bottle nipples. To sanitize, soak the block in a mixture of one gallon of lukewarm tap water and 1 tablespoon of 5.25 percent household bleach, or just fill the knife slots with the mixture. Let it sit for one minute, then rinse thoroughly with clean tap water and place upside down to dry. Avoid germ buildup by washing knives and letting them dry completely before you put them back in the block. Another place that holds a lot of germs, your phone screen. Here is how dirty it actually is.

Refrigerator vegetable drawer

Salmonella, Listeria, and yeast and mold are partying it up in here with your cukes and carrots, and a dirty drawer could contaminate new clean veggies you put in there, Lisa Yakas, a microbiologist and senior project manager at NSF, told CBSNews.com.

De-gunk it: NSF recommends that once a month, you remove the drawer from the fridge and wash the bin with warm water and a mild detergent. You can get rid of odors with a baking soda solution (about 1 to 2 tablespoons of baking soda in 1 quart of water). Let everything dry thoroughly. Watch out for these scary germs that could be lurking on your clothes right now.

Refrigerator meat drawer

It’s not surprising that the home of raw meat would host Salmonella, E. Coli, yeast and mold, but ask yourself: How often do you give it a proper cleaning?

De-gunk it: As with the veggie drawer, you need to remove the whole thing and wash it with soap and water.

Blender gasket

If you don’t follow the manufacturer’s cleaning instructions, you may be blending in bacteria with your food.

De-gunk it: Clean your machine after each use by disassembling completely, including removing the blade and gasket. Depending on manufacturer's directions, put the pieces in the dishwasher or wash by hand in hot soapy water. Let all pieces dry thoroughly before putting the blender together. These cleaning mistakes are making your home dirtier than it already was.

Can opener

Many people use this handy tool every day, but if you toss it back the drawer without a good cleaning, you maybe exposing your family to bacteria, yeast, and mold.

De-gunk it: It’s especially important to clean the area where the groove meets the can, and make sure you get rid of all food residue. Even better, buy one that’s dishwasher safe and wash after each use.

Spatula

If you don’t remove the rubber tip from your spatula to clean it, chances are food remnants exist, and that can lead to the growth of disease-causing germs.

De-gunk it: If your spatula is two pieces, separate the handle from the tip and clean both thoroughly.

Food storage containers with rubber seals

You may rinse out your lunch container in the office sink, but these containers can allow germs to thrive.

De-gunk it: If dishwasher safe, make sure to wash both the container and the lid. If you’re cleaning by hand, take special care around the seal and any grooves where the cover attaches to the container. Does bar soap really hold onto germs?