A new study reveals that dangerous germs lurk in 60 percent of refrigerators, and surprisingly, cleaning—not temperature—is the key factor.
Dortmund – Many of us open the refrigerator each morning, grabbing yogurt, cheese, or butter without a second thought. But a team of researchers at the University of Veterinary Medicine Vienna investigated whether that assumption is safe, and their findings may surprise consumers.
Study Finds ‘Disgusting’ Bacteria in 45 Household Refrigerators
The research, published in the journal LWT, involved taking samples from 45 refrigerators in private homes. Using advanced gene sequencing, the team identified the microorganisms present. The results showed hundreds of different bacterial species in every refrigerator, totaling 2,184 different species identified by the scientists.
In 60 percent of the refrigerators, researchers found pathogens that can cause illness. These included bacteria such as Bacillus cereus and Staphylococcus aureus, which can lead to diarrhea and vomiting. In some cases, they even detected Listeria – specifically, Listeria monocytogenes.
The German Federal Institute for Risk Assessment (BfR) classifies Listeria as rare but dangerous, particularly for older adults, pregnant individuals, and those with weakened immune systems. Listeria is particularly concerning since, according to the BfR, it can still multiply at refrigerator temperatures between -2 and 4 degrees Celsius (more consumer warnings).
Refrigerator Study Reveals: Cleaning is Crucial
Many consumers assume that as long as a refrigerator is cold enough, food is safe. This study challenges that belief. Only 38 percent of the refrigerators tested maintained a temperature of 5 degrees Celsius or lower, with 24 percent exceeding 7 degrees Celsius. Yet, temperature wasn’t the primary determinant of germ levels. What made the biggest difference was cleaning frequency: refrigerators cleaned less often harbored significantly more bacteria.
Even more concerning, the researchers found genes in many samples that confer antibiotic resistance to bacteria—similar to those found in hospital-acquired infections. These resistant bacteria were more prevalent in older appliances. The BfR notes that these resistance genes can be transferred between bacteria, potentially complicating the treatment of infections.
How to Protect Yourself: Keeping Your Refrigerator Clean
The good news is that regular cleaning can significantly reduce bacterial load. The Lower Saxony State Office for Consumer Protection and Food Safety (LAVES) recommends cleaning the refrigerator at least once a month—or immediately after spills or noticeable issues. Antibacterial coatings on some refrigerators, according to testing by the Stiftung Warentest, offer limited benefit.
Here’s how to properly clean your refrigerator:
- Remove all food, shelves, and drawers, and check expiration dates and spoilage although you’re at it—expired items should be discarded.
- Wipe down the interior walls, shelves, and drawers with hot water and dish soap on all sides—don’t forget the interior walls and drain.
- Glass shelves and removable parts like bottle holders or egg trays can be cleaned in the sink or dishwasher at a maximum temperature of 60 degrees Celsius.
- Avoid using abrasive cleaners—they can scratch plastic surfaces, promoting bacterial growth.
- Allow everything to dry completely before restocking food.
- Wash the cleaning cloth at at least 60 degrees Celsius to prevent the spread of germs throughout the household.
The researchers emphasize that consumers should treat their refrigerators with the same seriousness as kitchen countertops. Regular cleaning protects you and your family—regardless of whether the appliance is new or old.
