From pathogen outbreaks to product recalls, food safety is among the top of American consumers’ list of concerns. But what consumers don’t realize is the most likely risk of food poisoning is their own refrigerators. Foodborne illnesses occur in private homes three times more frequently than in commercial operations, and many occurrences of food poisoning are due to improper storage, unsafe food handling, lack of cleanliness and poor refrigerator maintenance. So to see whether Americans are keeping up good home food safety habits, researchers from Tennessee State University in Nashville, Kansas State University and the research firm RTI International conducted a series of studies that included Web surveys, face-to-face interviews, in-home refrigerator inspections and swab samples. And the results weren’t always pretty.

Chilling Fact 1: Fewer than half of Americans know the recommended temperature for a refrigerator is below 40 degrees Fahrenheit. Improper storage temperature is among the major factors contributing to food spoilage and microbacterial growth. Yet according to a study conducted through 550 in-person interviews in six states, 65 percent of participants did not know the recommended temperature for a refrigerator.

Chilling Fact 2: A large majority of Americans have no idea what the current temperature of their own refrigerator is. Of the survey participants, just 15 percent knew their own refrigerator’s current temperature. And of the 18 percent who said they own a refrigerator thermometer, very few checked them. “After we asked people whether they had a thermometer, we took a subset of that sample-—about 210 folks—and went into their homes and looked in their refrigerators,” says Sandria Godwin, PhD, RD, LDN, one of the researchers from Tennessee State University. “Only about 1 percent of those who said they had a thermometer actually did. We found that many of them were confusing the thermostat with a thermometer.”

Chilling Fact 3: Most refrigerators’ internal temperatures exceed safe recommendations. Using infrared sensors, researchers measured the internal temperatures of consumers’ refrigerators in three locations: the back wall, the door and the bottom shelf of the refrigerator. Overall, 76 percent of the refrigerators had back wall temperatures above 40 degrees F, 91 percent had door temperatures above 40 degrees, and 57 percent had bottom shelf temperatures above 40 degrees. “Our average temperature variance within the same appliance was about 7 degrees, but in some cases we found as much as a 20- or 30-degree differences,” says Godwin, who notes that extreme variances were found mainly in fridges with mechanical problems. The researchers also found doors consistently were warmer than other areas of the fridge. Godwin points out this is also the most common location of foods like milk, butter
and eggs. “When we were interviewed by an appliance manufacturer, we recommended they make the door shelves shallow so people wouldn’t put their milk cartons on the door,” she says.

Chilling Fact 4: Nearly half of Americans store food in ways that make cross-contamination of harmful pathogens possible. In fact, many people have spoiled food in their refrigerator right now. An in-home assessment of food storage habits revealed 34 percent of participants had unsealed or uncovered containers in their refrigerators, 29 percent had moldy or spoiled foods, 98 percent did not date their leftovers and 42 percent had conditions in which cross-contamination of pathogens was possible. “Eggs in particular we found out of the carton,” says Godwin, “and many people had no idea how long they had been in there.” According to the American Egg Board, fresh eggs can be stored in their cartons in the fridge a constant temperature of below 40 degrees F for four to five weeks beyond the carton’s packing date. “If they are kept fairly cold, eggs really don’t spoil as quickly as they may lose quality,” says Godwin. “However, most of those built-in egg trays in the refrigerator are on the door, where we know the warmest temperatures are.”

Chilling Fact 5: The area of the fridge most likely to harbor pathogenic bacteria is the produce bin. To evaluate the risk of microbial contamination in home refrigerators, researchers took swab samples from top and middle shelves, meat/poultry drawers, veggie bins and bottom shelves. The results: Vegetable bins were the most contaminated locations, followed by bottom shelves and meat drawers. And these weren’t just those harmless bacteria you find everywhere, either. The predominant enterobacteriaceae (which include many pathogens such as E. coli and Salmonella) found in home refrigerators were Klebsiella and Enterobacter spp. Some of these isolates are pathogenic —including K. pneumoniae, E. sakazakii and Yersinia enterocolotica—and 39 percent of the isolates showed resistance to erythromycin and 34 percent to ampicillin. Some even carry genes resistant to multiple antibiotics.

Chilling Fact 6: Very few people thoroughly clean their refrigerators, even if they say they do. According to one of the studies, 57 percent of participants partially clean their fridge about once a week, and 21 percent report thoroughly cleaning their refrigerator at least once every two weeks. But Godwin is skeptical. “We were specific about definitions. ‘Partially cleaning’ meant wiping down a surface or maybe cleaning the handprints off the door, and ‘thorough cleaning,’ meant emptying out the fridge, cleaning out the interior surfaces, removing the bins and shelves and washing and drying them,” says Godwin. “I_would question whether 21 percent really do that regularly.” Part of Godwin’s doubt comes from her most recent research in which she examines first-hand the conditions of home refrigerators. “We have found some very disturbing instances of, well, pure filth,” says Godwin. “It is a perfect example of [discrepancies between] self-reported behavior and actual behavior.”

Chilling Fact 7: A faulty door seal is among the most common fridge problems, creating condensation, mold and inconsistent temperatures. Even though a majority (67 percent) of the participants had refrigerators that were less than 10 years old and were purchased new, nearly 20 percent of those inspected by the researchers had faulty door seals. “We used several criteria for gauging the condition of the door seal,” says Godwin. “We looked for mold in the crevices of the seal. And we would close the fridge door and tug on it gently. If the seal were snug, there would be resistance. If the door opened easily, we knew there was something wrong with the seal.” Over time, door seals can become dry and cracked, allowing condensation to build up (hence the mold) and internal temperatures to become inconsistent. But while leaky door seals may be a fairly common occurrence, there is no need to replace the entire appliance. Have the seal replaced by a repair service professional, or if you enjoy do-it-yourself projects, look for seal replacement instructions on your refrigerator manufacturer’s Web site.

Chilling Fact 8: Many Americans store more than food in their fridge. One of the studies that included a refrigerator inventory assessment found a number of non-food items in refrigerators, including: batteries, medicine, pet food, plants, camera film, tooth bleach, airplane tickets, cigars, dried flowers, paint brushes, candles and fishing worms. Shaping home food safety messages: When it comes to home food safety education, consumer research suggests a need to get back to the basics—washing hands, disposing of old food, cleaning the fridge—in addition to being sure refrigerators work properly and keep an internal temperature under 40 degrees F. Furthermore, it seems everyone could use a lesson in home food safety. “Our surveys indicate that the people who are least likely to follow home food safety recommendations have higher education, greater income and live alone,” says Godwin. “This data is not definitive, but still it suggests perhaps we should be targeting a broader audience than many current food safety programs typically do.”