Risk of food borne illness in healthy adult

Factual Questions
1

I’m looking for information on the health risks associated with food left out overnight. Specifically the question at hand is: “1 in how many people get food poisoning from eating pizza left out overnight?” This is to win an argument with my silly silly husband, so I really need your help. :cool:

So, last night I made lasagna for dinner. Mmmm. Warm and gooey and delicious. After we ate, my husband played a game with his brother and I worked for a few hours until it got pretty late, and then we went to bed. I completely spaced on the leftover lasagna that had been sitting out on the table. This morning I woke up to the disappointing mess.

I sighed, and said to my husband, “Aww. I left out the lasagna. No leftovers for us.” He scoffs and says his immune system can take it, and eats a bite. I say that’s gross, and that it’s basic food safety–there’s bacteria all over that because it’s been left out for hours. He says I cooked it safely last night. I say that more bacteria have come in the night to the feast. He counters that he’s seen me eat leftover pizza that’s been left out in the box on the table all night. I say just because I’ve been disgusting doesn’t mean the risk isn’t there. He charges me to prove it, saying if it’s so dangerous, why haven’t we gotten food poisoning yet. I say it’s dumb luck.

And here we are. I’ve been able to find links from the FDA that discuss how to store leftovers and at what temperature, and the risks associated with young/old/pregnant people, but he says that doesn’t answer his question. :rolleyes:

So I ask the Straight Dope: Who’s right? Is the risk of food poisoning (from properly prepared food left out overnight) significant to the average healthy adult? Anyone know about any reputable studies on this topic?

2

bump

Just to clarify–I’m looking for information specific to the risks associated with healthy adults eating food that was previously perfectly safe, but has been left out in the average home for about 8-12 hours.

Yes, to anyone else, it would be obvious, and no, he’s not scoffing at food poisoning–at this point he’s just being stubborn, and hard numbers will shut him up. The only statistics I’ve been able to find are estimates of the number of cases per year and the number of deaths per year in various countries, but of course those numbers will include people with compromised immune systems and people who never wash their hands.

Looks like “old food is bad, dummy” is such an obvious thing that I’m finding it hard to find detailed stats or a risk analysis, and I’m just coming up with details on the various illnesses and how to prevent them.

ETA: yes, this is quite possibly the dumbest question ever, and if no one replies I’ll happily let this thread die a quick death.

3

It’s going to depend on a lot of factors, the most significant of which are ambient temperature/humidity and the specific pizza (i.e. pork sausage, pepperoni, type of cheese, etc.).

So how about an easier question. What kind of harmful bacteria can grow on food that has otherwise been properly cooked and not exposed to any uncooked foods? Or is the fear that cooking might not have killed all the harmful bacteria and now it has a chance to grow?

4

Food poisoning in the sense that some significant levels of toxin has been deposited in the unrefrigerated food? Bacteria would need time to grow and multiply before they exist in numbers large enough to excrete toxic byproducts. IANAMicrobiologist but to my knowledge, aerobic bacteria don’t produce nasty toxins like some anaerobic bacteria do. They produce fairly benign waste from their metabolic processes, such as alcohol via fermentation. Contamination by insects and vermin would be a greater threat.

I would eat your leftover lasagne without a second thought.

5

That’s a good point–if it sat there long enough to have enough dangerous bacteria, it might have been rendered inedible because of other factors long before, especially if it was sitting out in a clean apartment with no pets.

6

If food poisoning were as simple as eating stuff left out overnite, our college campuses would be full of kids vomiting from food poisoning instead of drunkenness…anyway…

“Food poisoning” is used as a loose slang to refer to two different categories of illnesses.

The first is a pre-ingested toxin. Bugs are growing in the food; they produce toxins; you eat the food with the toxin already in it and within a few hours you are vomiting and/or running off at the bowels. Sicker than a dog and you normally get better pretty fast, also.

The second way it’s sometimes used is that you ate food with bad live germs in it. You get the germs; they grow and multiply happily inside you and you get sick with an active infection of whatever bug it is (campylobacter, say, if you care).

The first thing you need to get food poisoning is an inoculum of a naughty germ–on the food for a preingested toxin; in your mouth for a foodborn active infection in your gut. Mr filthy hands lettuce picker touches the lettuce, contaminates it with a pathogenic strain of e coli; you eat the lettuce and the next thing you know you are hoping to be part of a class action against Dole.

I think you and the husband are talking about pre-ingested toxins, though. Food started clean. You leave the food out. It grows bacteria. They make their toxin. You spend the day in the bathroom or in my ED.

The answer to how common this is depends on whether or not the right (wrong?)bacteria got incoculated, what the food medium was like, and how robust the eater is. If by “properly prepared” you mean the food started off sterile–i.e. however it was prepared, it was enough to kill any bacteria it started with–then stuff left out overnite is not likely to be growing anything particularly terrible unless you and the old man brought that germ to the table (course if ya left something in a pizza box contaminated by the filthy kid who works at the nearby pizza parlor, all bets are off). It would be growing staph, for instance, but probaly not the kind of staphylococcus that gives you food poisoning. On the other hand, if the salad started off with a bad germ on it, simple refrigeration isn’t going to sterilize it, and you might get sick even if you didn’t leave it out.

Some bacteria prefer certain media, so the type of food can make a difference.

If you just want to win the argument by assuming the worst, it’s possible that “properly prepared” food newly contaminated by the mister’s unwashed hands will grow enough toxin-producing bacteria within a few hours to make him sick. It is, alas, unlikely for food prepared in your home, because you wouldn’t even be getting into this argument if you weren’t a neatnick, and surely the old goat showers at least once a day, too. It’s unlikely you have the right kind of germs running around in the first place.

This is why little Timmy can eat 5 day old dog poo, fer goodness’ sake, and survive. It’s also why that one tribe in the Amazon can bring home dead monkeys already rotting and enjoy the softened meat. Plus they have fairly robust host defenses, I’d say.

Now could you please convince my wife of all this? I only get about ten minutes before the milk has to get into the fridge, and god help us if we don’t come straight home from the grocery store. Nor will she be accompanying me on my adventure to the Amazon.

ETA on review this is disorganized. My apologies. Past my bedtime. I hope you get the idea.

7

My degree is in microbiology, for what it’s worth. Basically, if you leave food out in the “danger zone,” meaning a temperature that’s not too hot or too cold for bacteria to grow, then you’re taking some risk. Stuff could have survived to start growing - it’s possible. But in my opinion, food safety is much more important for big restaurants that are serving zillions of people every day. At home, well, I’ll just say that I would have eaten the leftovers quite happily. The risk isn’t as big as most people seem to think it is.

YMM, of course, V.

8

d’oh! Guess I lose this one.

Yes, I was talking about food that hadn’t been contaminated previously–how bad could it really get a relatively clean environment.

I kinda figured the risk wasn’t that big, I mean, like I’ve said, I’ve eaten stuff left out overnight, and not gotten sick. I thought there might be a chance that it could be worse than the average person assumes, though. But, like you say, I have to imagine that our ancestors would never have survived on things like rotten Amazonian monkeys if we couldn’t take the occasional germ. Mostly, the lasagna just grossed me out, but not him, and we got curious about the actual risks involved–how big a deal it really is.

Ignorance fought–it does make sense that the advice from the FDA and CDC would be overboard to compensate for the potentially gross behavior of the general public. (For those who are curious about its fate–the lasagna did end up in the trash, mostly because the noodles were crusty.)

Well, if it helps, you’ve convinced me. Of course, I’m not as big a neatnik as this whole thing makes me sound. I’ve even been known to eat cookie dough with raw eggs in it, so I know how to live dangerously. :cool: (Now watch, next time I’ll get salmonella…)

Thanks, everyone, especially Chief Pedant and Smeghead for your professional opinions.

9

Part of this may be due to the fact that the most common bacteria in your home are ones that your digestive system is used to handling. That’s why mexicans have no problem drinking the same water that makes tourists very sick.