Homemade pizza left out overnight

I'd say it depends. If you are dead-set on observing all food safety rules, the pizzas are probably unsafe to eat. But in the real world, it is possible to bend some of those rules and get by unscathed. But you have to be smart about it--not all rules safely bend as far as others.

What was on the pizzas? Shrimp? Chicken? Raw sausage? Those things have a pretty short safety window. Cured meats like pepperoni are safer longer (that's why they're cured in the first place).

How hot was your kitchen?

How long did they sit out?

And then of course it comes down also to how long and how hot you're cooking things. You might well be able to kill off germs in things that aren't outright spoiled. Pizza isn't that long-cooking, so there's risk there.

Ultimately, you have to be the arbiter of safety. Check the USDA website about food safety and follow every rule if you want to feel certain.

When in doubt, throw it out. (anon)

12+ hours is an eternity for microbial life—who need only food, water, and amicable temperatures to multiply quickly. Most guidelines suggest throwing cooked food that's been held at room temperature after 2 hours (1 hour if the ambient temperature is over 90F).

Note that the risk is in both the pathogens shipped with the food, and the ones introduced by anyone handling it during and after cooking it (cross contamination is the greater risk here). The risk after 24 hours is significant, and could result in severe infection. Do not eat this food.

You will not always get sick after eating pizza left out for 12+ hours, but when the food happens to be cross-contaminated that amount of time is enough to brew a large colony of nasties, enough time that heat will not necessarily kill the entire colony. So the times that you do get sick, you run the risk of getting very sick. No fun at all!

Further reading:

• US food safety guidelines
• Canadian safety guidelines
• Wikipedia on Food Safety

If there is no raw meat on them, I'd imagine they'd still be safe (the crust will have over-proofed, though). I would not eat them if there is any raw/uncured meat on it. I can't think of any other ingredient that would spoil dangerously overnight.

Also, all of these rules are designed to absolutely avoid hazards, and much of it has to do with how hearty your immune systems are. In a deli or restaurant it is not unusual for these type of ingredients to sit out for many hours, and not5 cause problems, particularly after being cooked.

With no raw meats, I would say that you are safe unless members of your family are prone to food-borne illness, probably would be susceptible if your family is very cautious about germs and 'over-sanitizes.' If not, you should be OK.

This may depend a lot on where you live, and the atmosphere of your kitchen. In general, I would agree with other commenters that the risk is probably minimal. However, there was a flat I lived in once where in warm humid weather, most cooked food would go visibly mouldy within 24 hours if left out (so was probably not good to eat after about 6–8 hours). So, if you have some past experience of how quickly food goes mouldy in your kitchen, that could also be worth taking into account.