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What is a 5 second rule?

The 5 second rule is an informal rule around food hygiene that states food is still safe to eat if it is picked up within 5 seconds of being dropped on the floor. The idea is that dangerous bacteria don’t have time to contaminate the food in such a short timeframe. While there is no scientific evidence to support the 5 second rule, it remains a popular guiding principle that many people use to decide if food is still edible after being dropped.

Where did the 5 second rule come from?

The origins of the 5 second rule are unclear, but it seems to have become popular knowledge sometime in the 20th century. Some possible theories for where it originated include:

  • A study from the 1970s and 1980s suggested that food picked up quickly was less likely to contain bacteria. This may have led to the popular 5 second timeframe.
  • It derives from an old food safety guideline to only leave perishable foods like meat and dairy out at room temperature for less than 5 hours. The 5 seconds timeframe may have informally morphed from this.
  • It started as a convenient rule of thumb that people found useful, even if lacking scientific merit. The short timeframe of 5 seconds feels intuitively safer.

While the exact origins are unknown, the 5 second rule seemed to spread as a popular food safety myth sometime in the late 20th century. Though completely unproven, it remains widely known today.

Is the 5 second rule legitimate?

There is no robust scientific evidence to support the 5 second rule. No studies have conclusively proved that food picked up off the floor within 5 seconds is less likely to contain bacteria or be unsafe. However, a few studies have tried to determine if the rule holds any truth:

  • A 2007 study found that moist foods like strawberries and bread picked up more bacteria than dry foods like cookies when left on dirty surfaces. But there was no evidence that food picked up in 5 seconds or less was substantially cleaner.
  • Another small study from 2006 found that carpeted floors transferred the least amount of bacteria to dropped foods. Food dropped on surfaces like tile and wood picked up more bacteria. But again, the 5 second timeframe itself was not proved.
  • A final study found that longer food contact time with a contaminated floor did result in more bacteria transfer. But even food contacted for just 5 seconds picked up a considerable number of bacteria.

Overall, current research suggests there is no truly “safe” amount of time for handling dropped food. While the 5 second rule is catchy, it should not be taken as sound scientific advice.

Factors influencing food safety when dropped

If food does happen to hit the floor, there are a variety of factors that can influence the likelihood of bacterial contamination, including:

  • Surface type – Carpets or rugs are less likely to transfer bacteria than hard surfaces like tile or wood.
  • Floor cleanliness – Cleaner floors tend to have less bacteria to transfer.
  • Food type – Moist and porous foods are more susceptible to contamination than dryer items.
  • Food contact time – The longer the food rests on the floor, the greater chance for bacterial transfer.

So while the specific 5 second timeframe is unproven, the general principle that reduced floor contact time limits contamination does have merit. But many factors influence potential food risks when dropped.

Foods more prone to contamination

Not all foods carry the same level of risk when dropped on the floor. Moist and porous foods are more likely to become contaminated than harder or drier items. High risk foods include:

  • Meat products
  • Fish and seafood
  • Wet produce like strawberries
  • Sliced fruits like watermelon
  • Bread and baked goods
  • Liquid foods or sauces
  • Foods with creamy fillings like donuts or sandwiches

On the other hand, lower risk dropped foods include:

  • Hard fruits and vegetables with peels, like apples and oranges
  • Firm produce like carrots
  • Dry snack items like chips, pretzels, nuts
  • Hard candies and wrapped chocolate bars
  • Dried fruit

Where moist foods may quickly soak up bacteria, harder and drier items have less surface area for bacterial transfer. But these lower risk foods can still pick up some contamination when dropped.

Safest options if food is dropped

If food happens to drop on the floor, here are some recommendations for how to handle it:

  • If possible, inspect the food first. Discard anything especially soiled or wet.
  • Consider floor cleanliness. A visibly dirty floor carries greater risks.
  • Wash or peel produce to remove contaminated surfaces.
  • Avoid any ready-to-eat items that directly touched the floor.
  • When in doubt, throw it out. Don’t risk eating anything potentially contaminated.

Following the arbitrary 5 second rule is not guaranteed to prevent illness. Use best judgment based on food type, floor cleanliness, and preparation steps needed before eating.

Potential risks of eating dropped foods

Eating food contaminated with bacteria from the floor does carry potential health risks. While a serious illness is unlikely from an isolated dropped food incident, dangers can include:

  • Salmonella – Causes diarrhea, vomiting, abdominal cramps, and fever.
  • E. coli – Can lead to severe stomach cramps, diarrhea, vomiting and fever.
  • Campylobacter – Leads to cramping, abdominal pain, nausea, and diarrhea.
  • Staph aureus – Causes nausea, vomiting, and abdominal distress.

Dangerous mold species may also contaminate dropped food in some cases. People with compromised immune systems are most at risk when eating potentially contaminated foods.

Food handler hygiene influences risks

How likely dropped food is to make people sick also depends on who handles it. Even a briefly dropped food can pose risks if handled by someone unhygienic. Important food handler hygiene practices include:

  • Washing hands thoroughly before cooking and eating.
  • Avoiding touching ready-to-eat foods with bare hands.
  • Keeping kitchen surfaces and utensils clean.
  • Not working around food when ill.

Someone disregarding basic food hygiene is more likely to transfer bacteria from hands to dropped food. Good handler hygiene helps mitigate risks.

Home kitchen floor bacteria

Bacteria commonly found on home kitchen floors which could contaminate dropped foods include:

Bacteria Potential Health Effects
Staphylococcus aureus Food poisoning
Salmonella Diarrhea, vomiting, cramps, fever
Listeria monocytogenes Flu-like symptoms
Campylobacter Diarrhea
Clostridium perfringens Cramps, diarrhea
Bacillus cereus Nausea, vomiting

These bacteria find their way onto kitchen floors from spills, contact with shoes and pets, and through improper hygiene habits. Proper cleaning helps minimize contamination levels.

Bacteria levels on various floor types

Studies analyzing bacteria transferred to dropped foods have looked at how different floor types compare. Typical bacteria levels found include:

Floor Type Bacteria Levels
Tile 10,000 – 40,000 CFU/100 cm2
Laminate 14,000 CFU/100 cm2
Rubber Mat 31,000 CFU/100 cm2
Carpet 4,000 – 11,000 CFU/100 cm2

CFU stands for colony forming units. Harder floor surfaces tend to harbor more bacteria than carpeted floors. Regular disinfecting can help lower contamination levels.

Most germ-ridden kitchen items

In addition to floors, other kitchen items commonly covered in bacteria include:

Item Bacteria Levels
Sponges 10 million-10 billion CFU/100cm2
Dishcloths 4 million-145 million CFU/100cm2
Sink 500,000 CFU/100cm2
Faucet handles 40,000-801,000 CFU/100cm2
Counter tops 100-100,000 CFU/100cm2
Cutting boards 1,000-1 million CFU/100cm2

Kitchen sponges and dishcloths tend to be the germiest, especially when left damp. Proper cleaning and replacement helps control bacterial growth.

How to disinfect a kitchen floor

To help minimize bacteria that could transfer to dropped food, regularly disinfect kitchen floors. Methods include:

  • Sweep and mop floors at least once weekly.
  • Use a disinfecting floor cleaner or bleach solution.
  • Steam mops can sanitize floors very effectively.
  • Disinfect any obvious problem areas as needed.
  • Avoid just using water, which can spread bacteria.
  • Let floors fully air dry after mopping.

Mopping floors with a disinfecting solution kills bacteria, lowering risks from any food drops throughout the week.

Can you teach kids the 5 second rule?

While the 5 second rule is not objectively true, many parents teach it to young kids as a way to avoid wasting food. If educating kids about the rule:

  • Emphasize hand washing before eating any dropped food.
  • Only apply to certain foods like dry snacks.
  • Don’t allow consumption of obviously soiled or wet dropped food.
  • Have kids help clean floors before eating off them.

Label the 5 second rule as a “game” so kids don’t view it as sound science. Take into account factors like food type and floor cleanliness.

Does the 5 second rule apply to pets?

The 5 second rule is sometimes jokingly applied to pet foods dropped on the floor, especially treats or table scraps. However, health risks of feeding pets floor-dropped food can include:

  • Ingestion of harmful bacteria like salmonella or E. coli leading to gastrointestinal illness.
  • Consumption of inedible foreign objects like small rocks that happened to be on floor.
  • Eating spoiled human foods that pets’ digestive systems cannot handle.

As with human foods, the 5 second rule offers no reliable protection against contamination dangers. Dropped pet foods are better discarded or thoroughly inspected before serving.

Does the 5 second rule apply to babies?

Parents should never purposely feed floor-dropped food to infants or toddlers based on the 5 second rule. Young children are especially vulnerable to illness from bacteria. Dangers include:

  • Developing food poisoning, diarrhea, or vomiting from contaminated items.
  • Potential choking hazards from eating small non-food particles picked up from the floor.
  • Greater likelihood of suffering dehydration from gastrointestinal illness due to small body size.

The 5 second rule offers no real protection for small children. Their developing immune systems are vulnerable to pathogens in floor-dropped food.


While the 5 second rule has endured as a popular food safety myth, it does not offer reliable protection against bacteria on floors contaminating dropped food. Time is just one factor influencing contamination risks. Food type, floor cleanliness, food handler hygiene, and preparation steps also contribute. The safest option is discarding obviously soiled or wet dropped foods. But with caution, even brief floor contact may not always necessarily make every food dangerous to eat if inspected and handled properly afterwards. Though no time limit truly guarantees safety, the 5 second rule conveys some reasonable principles about limiting exposure to dirty surfaces. But it should not replace more rigorous food safety practices.