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I have only recently discovered that cooked food shouldn't be left in room temperature for longer than 2/4 hours.

I lived in a tropical country which is warm and humid and I have been growing up eating left over cooked food(meat, rice, bread, dairy products and left in 30C for longer than 6 hours) with no issues. In fact it's very normal to the people in my country.

So my question is the 2/4 hours only a strict guide for commercial food seller? How come people in my country do not have issues with leftover food? Is this habit a silence killer which only breaks out when we grow old?

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    The rule is less used to say "that and that is unsafe", but "that and that is safe, without having to further look into what the cooked food consists of" for cases (as you said, commercial is an example) where you can't risk being unsafe, or make certain you are safe. At 30°C even shorter times could apply. Bread is usually not considered a perishable food, for meat and rice 6 hours at 30C sounds patently unsafe, same for dairy unless it is intentionally being fermented in a controlled manner. – rackandboneman Dec 7 '15 at 3:22
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    I don't know where you're from, but I suspect the premise in your question is wrong: people probably do get sick from food there. They might just not realize that it's the cause. – Cascabel Dec 7 '15 at 6:53
  • The recommendations are based on health guidelines for restaurants -- where they have a much higher risk of problems (more people == more likely to have a person w/ a weakened immune system ... and they risk getting hundreds of people sick, rather than just one family). There are people out there who specifically recommend eating spoiled foods (even meat) as a form of probiotic, but very few people have the stomach for going it with anything other than dairy products (ie, yogurt & cheese). The real risk is botulism -- it doesn't take much, and the effects are nasty. – Joe Dec 7 '15 at 11:53
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    If you want to eat food that's been out for longer than 4 hours, that's a risk that you can decide (although, it helps to know what's in the food, to know what the risks are) ... but I'd avoid serving food that's been left out for long periods to other people, as they might have a compromised immune system or other issues that increase their risk. Of course 'long' is likely as local determination, as it's possible that people in your region are better able to handle the bugs in your area, and that Americans have weak immune systems from over-hygiene. – Joe Dec 7 '15 at 11:59
  • Anyone from the FDA will tell you to obsessively wash and disinfect anything that has some into contact with any type of raw beef. But if you ask your local french restaurant how they source their beef tartare, they'll tell you they get chuck from their local butcher and grind it up. And serve it raw. So, how can you obsessively sterilize anything that has come into contact with this raw meat, just to then put the entire piece of raw meat in your mouth and eat it? I wish there were studies that had some type of justification for these random "4 hour" suggestions, other than "It's safe". – Nicholas Pipitone Apr 28 at 20:46
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The food safety guidelines are based on scientific & mathematical calculations along the lines of:

Given an initial bacteria count of X they will under the given conditions mulitply to a number of Y amd have produced Z [unit] of toxins.

Now what to do with these values?

We use them like seat belts or helmets. Not wearing a seat belt will not automatically kill you, only if you are involved in an accident you are much more likely to suffer severe injury or death without it. Still, nobody could responsibly recommend ignoring a seatbelt, knowing that accidents do happen. But with food safety, many are willing to skip their seat belt, so to speak.

One very common misconception is that contaminated food can be detected by smell, looks or taste. Yes, some kind of spoilage is obvious, but many, especially the more dangerous ones, are not "visible". One very prominent example is Salmonella. Note that many toxins are not destroyed by cooking, more details in our canonical post.

I can guarantee that people in your country have issues with cases of foodborne illnesses - all countries do. You need to keep in mind that

  • Foodborne illnesses need not become apparent immediately or shortly after a meal. The symptoms of Salmonellae, for example, might start as late as 72 hours after infection. It is likely that the connection between a sudden bout of sickness and a meal eaten three days prior is simply overlooked.

  • In healthy adults infections may pass unnoticed or cause only mild sympotms like indigestion. The human body can handle a certain amount of bacteria or toxins, the individual levels of tolerance vary, though. So children, elderly people or those with a compromised imune system are more likely to suffer and have a higher chance of severe complications or death. The given safety guidelines are calculated to protect these groups as well. Also note that often the side-effects are as dangerous as the pathogens themselves, diarrhea being a classic example.

  • There is no way of determining the amount of bacteria present in a specific dish, piece of meat or other food prone to spoiling - unless you get a lab involved. The values used to calculate safe thesholds contain a certain safety margin. Your dish could contain fewer bacteria to start with or if any were present, they might not have multiplied that much. (But they might as well have, we can't safely know.) The two/four hours rule simply means that the food will remain in the safe range, not that it will be spoiled afterwards.

So what now?

It is entirely up to you to whether you choose to drive with or without seatbelt or helmet. Make an informed devision and consider the welfare of those weaker than you. What you as a healthy adult can stomach (pun intended), might be fatal to a young child or weak elderly person.

Only a few days ago the WHO published a news release on foodborne diseases:

  • First ever estimates of the global burden of foodborne diseases show almost 1 in 10 people fall ill every year from eating contaminated food and 420 000 die as a result
  • Children under 5 years of age are at particularly high risk, with 125 000 children dying from foodborne diseases every year
  • WHO African and South-East Asia Regions have the highest burden of foodborne diseases

(Source)

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    In fact, driving without a seatbelt/helmet is pretty common in tropical countries :D – user280593 Jan 18 '17 at 20:14
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Yes, that's generally thought to be true — as determined through the science of modern food safety. You can read about specific guidelines on the Food-Safety tag wiki. Those practices were developed as broad recommendations, usually erring on the side of caution.

That being said, you might be able to get away with it sometimes, without dying of food poisoning, but it could be risky. Much depends on the food itself — bread left at room temperature may last for days, but you could have problems with meat or dairy products after just a couple of hours.

Bacteria and other harmful pathogens can exist everywhere. At room temperature, those organisms can multiply very rapidly, producing toxins that can make you sick. You can NOT rely on smell to detect them — food can be highly infected, but smell and taste just fine. That's why, for safety, it's important to refrigerate or freeze cooked food to slow down the growth of any pathogens.

It's best to do this as soon as possible after the food cools down to room temperature. You also want to avoid putting hot food directly into the refrigerator because it may heat up the 'fridge, affecting other food inside, and actually delay your food cooling down to a safe temperature.

Food poisoning isn't something that only breaks out when we grow old, though elderly people, young children, and those with weak immune systems can be more susceptible.

As leaving cooked food at room temperature was "normal" in your country, I wonder if there wasn't also a prevalence of food poisoning that was also just considered "normal'. How often did people have upset stomachs or diarrhea, and just accept it as part of everyday life?

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    This is a good answer. The only point I'd note is that if you're following recommendations from most food safety organizations, you shouldn't wait until the food "cools down to room temperature." Once it gets under about 130-135F, bacteria can start to grow. Most modern fridges won't warm up appreciably if you put hot or warm food in them, and most food safety organizations recommend refrigerating earlier rather than cooling to room temperature first. You obviously just want to keep any hot food away from highly perishable foods (e.g., raw meat) in the fridge. – Athanasius Dec 7 '15 at 18:26
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    Your first and second paragraphs are actually saying the same thing. What's true is that it's dangerous to eat food that's been out that long, where "dangerous" doesn't mean "you will get sick" (a common misconception) but rather "there is significant risk of getting sick." Presenting them as a contrast like that might encourage the misconception. – Cascabel Dec 10 '15 at 20:10
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The woman that mentioned she lives in a tropical, humid country where it is normal to leave food out and no one gets sick....well, this is exactly what I am observing right now. I am living with a woman that leaves chicken, turkey, hamburger out on the counter as soon as she brings it home from the store. She leaves them out all night long and sometimes all the next day. Then she cooks it for dinner. No one has gotten sick, including me. Although, her husband did eat a hamburger patty, supposed to be frozen, but left in the fridg for a week..he was vomiting that night. He commented that,"I ate to much." :( I knew better. I come from a family that wouldn't leave meat or cooked food out for longer than 20 min. So, I was so shocked coming into this environment. But, I have never gotten sick either. Weird. I never worry about it to much anymore. She does keep the meat covered tightly and cooks it at a very high heat, or microwaves it. Now I'm thinking, we are to paranoid about food. Or, maybe the heath inspectors make more money off restaurants with their impossible "food safety" expectations. So, they easily get violated and fined. Or, they need to loosen up a little. She also leaves cooked food out all night long for people to eat when they are hungry. The only things she does put in the refrigerator are dairy products, mayo, things like that. She also leaves her eggs out. This past Thanksgiving, she left the turkey out on counter for 3 days...it was warm to touch..she cooked it, we ate it, no problems. She leaves stuffing in the bird, no problems. She told me she usually leaves the turkey outside so it can get "real warm and liquidity" inside, because it cooks better that way.She was upset because I put the turkey in the refrigerator when I noticed it was warm. And she has been cooking like this for 30 years with her family.

  • Note that the recommendations do not say "it will be spoiled or poisonous after X time" but that "after X time we can not guarantee that it will be safe for everyone, including small children". And no, it is not because health inspectors "make more money" that way. – Stephie Dec 10 '15 at 20:07
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    Compare to this: If a woman gives birth and the midwife doesn't wash her hands, it is not guaranteed that she will get childbed fever. In fact, surprisingly many women will be fine. But clean hands / gloves and basic hygiene can lower the risk of an infection to almost nill. It is similar with food safety, the time / temperature recommendations acting as "gloves". – Stephie Dec 10 '15 at 20:10
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    Quite honestly, your advice here is dangerous and wrong. The reason that authorities discourage this is that if everyone does it, a lot of people will get sick - especially people with weaker immune systems like children and elderly people, but it could be anyone - and some of them could easily die. The fact that some people have gotten away with it for some amount of time (possibly discounting a lot of stomach aches and such along the way) doesn't mean it's safe. This is like pointing at some people who've been smoking their whole lives and saying, see, no cancer! – Cascabel Dec 10 '15 at 20:13
  • Quite honestly, dreamnart did not give advice - merely a fascinating anecdote, (which wasn't really an answer either, but valuable because of the horrifying level of detail). – Lorel C. Aug 27 '16 at 3:34

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