I've been part of many discussions about why it's unsafe to store cooked food at room temperature past two hours. An old question (How long can cooked food be safely stored at room/warm temperature?) links to USDA with common guidance that it is not safe to keep cooked food at room temperature for beyond 2 hours.

However, government agency policies are fairly opaque. Here are specific questions:

If meat is cooked in a slow cooker, what happens to it once it cools off and is left at room temperature for over two hours? If it was safe to eat when it was hot, what happens past two hours? How to bacteria get in (were they already in) and when do toxins form?

I am looking only for published article citations, not common sense, government recommendations, popular websites of personal experiences. Pubmed preferred but anything goes, any study that either measured toxins/bacteria or was able to correlate cases of food poisoning to food storage. US/Canada preferred.

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    Downvoted for "lack of research effort" on a stunningly well-covered subject. Most of it so well covered so long ago you'll need microfilm rather than pubmed to find it.
    – Ecnerwal
    Commented Jun 8 at 21:35
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    I have spent time Googling, asking AI and generally poking around. The problem is not lack of information, the problem is the noise to signal ratio, this is why I’m asking for references. Commented Jun 8 at 22:49
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    I find the formulation 'unsafe past two hours' somewhat unfortunate. The guidelines say that it is guaranteed to be safe up to two hours. To me 'not guaranteed to be safe' and 'unsafe' are not quite the same thing.
    – quarague
    Commented Jun 10 at 6:12
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    @Ecnerwal Sorry, but the absolute safety is not correct. They determined an acceptable (very very small) risk and then provide guideline how to achieve that. Safe at all times from everything is simply impossible and no guideline will ever claim that. The difference between sticking to the 2 hour guideline and using 4 hours instead is the difference between 99.9% versus 99% or something like that.
    – quarague
    Commented Jun 10 at 12:41
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    asking AI The SNR was too low so you went to the noise factory, lol Commented Jun 10 at 23:08

1 Answer 1


Picking one of many bacteria with heat-resistant spores:

Prevalence of B. cereus in meat:


Heat resistance of B. cereus spores



Growth rates (which go hand in hand with toxin formation once the spore has returned to the vegetative state):

https://www.sciencedirect.com/science/article/abs/pii/S0168160597001104 (abstract only - article paywalled)

https://www.sciencedirect.com/science/article/abs/pii/S0168160521003792 (abstract only - article paywalled)


Since you only want citations, you'll have to connect the dots yourself. Nobody got research funding to explain how heat resistant spores in your room temperature crockpot turn into unsafe food unless perhaps it was 1920-30 era research funding.

Or perhaps this rather general published article will help:


As for the supposedly opaque intent of the USDA guidelines, they are to "protect the health of the public by providing food safety". But I'd have to refer you to a government site for that quote.

As an example of USDA responding to better data, (y'know, food science) they altered their unground meat temperature guideline for pork from 160°F to 145°F with a 3 minute rest added back in 2011. Ground meat remained at 160°F with poultry at 165°F

This comes pretty close to being exactly on point for what you asked, for Clostridium perfringens and has 64 references to lead you further if you click through to the fulltext.


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    Canned meat is pressure-canned at higher temperatures for times proven to be adequate to kill all spores - except when it isn't, and there's an outbreak - more common in home-canned than commercial products, but still happens in commercial products sometimes. Some light reading on the grand-daddy spore-former that's typically the highest concern, Clostridium botulinum: academic.oup.com/cid/article/66/suppl_1/S73/4780431?login=true
    – Ecnerwal
    Commented Jun 9 at 20:17
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    on another note, many countries like mine have food vendors that is kinda like chipotle or the likes with cooked chicken of fish just hanging out there from morning till , well until they are sold , respect to our body for fighting all those pathogens. Commented Jun 10 at 4:12
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    @encryptoferia we get that statement often, but it's based on false assumptions. Food safety standards are to define a safe time and temperature in a way that protects also vulnerable groups. It doesn't mean that beyond that slot everything immediately becomes rotten. See a more lengthy elaboration here.
    – Stephie
    Commented Jun 10 at 12:44
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    I cannot find any support for two hours being a dangerous period of time in any of the links you provide. (Of course, many are abstract-only, and I may have missed something.) Most of them do not contain specific time values but try to fit models to experimental data or compare various environmental and matrix conditions relative to each other. Where times are mentioned (e.g. in researchgate.net/publication/…) they are in the 18+ hour range. Commented Jun 10 at 17:12
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    Also, a condescending remark like "nobody got research funding to explain how heat resistant spores in your room temperature crockpot turn into unsafe food unless perhaps it was 1920-30 era research funding" is inadequate and false as well: Because germination and growth speed e.g. for Bacillus cereus varies between and even within strains and is highly dependent on a host of environmental and growth matrix conditions there is clearly room and funding for ongoing quantitative research, which is what the OP asked for. Commented Jun 10 at 17:17

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