# Why didn't our lunches make us sick? **URL:** \ **Category:** Factual Questions\ **Created:** [February 26, 2012, 5:07pm UTC](https://boards.straightdope.com/t/why-didnt-our-lunches-make-us-sick/614061 "2012-02-26T17:07:23Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![aceplace57](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aceplace57/32/3500_2.png) [@aceplace57](https://boards.straightdope.com/u/aceplace57)\ **Post date:** [February 26, 2012, 7:23pm UTC](https://boards.straightdope.com/t/why-didnt-our-lunches-make-us-sick/614061/21 "2012-02-26T19:23:54Z")
I can’t recall ever being in a schoolroom that wasn’t heated & air conditioned. Once in awhile a warm winter day might result in a hot classroom and the teacher would open a couple windows. But, I’d say for sure it never got over 79 degrees in school. Lunches aren’t going to spoil that quickly in only 4 hours before lunch. Some parents would resend lunch items. You’d find that uneaten apple or banana in your lunch the next day. I’d certainly hope no parent ever sent yesterdays uneaten sandwich again. That would be dangerous. ---
**Author:** ![Smeghead](https://avatars.discourse-cdn.com/v4/letter/s/f1d935/32.png) [@Smeghead](https://boards.straightdope.com/u/Smeghead)\ **Post date:** [February 26, 2012, 7:46pm UTC](https://boards.straightdope.com/t/why-didnt-our-lunches-make-us-sick/614061/22 "2012-02-26T19:46:24Z")
I’m seeing a lot of not-quite-right information here about mayonnaise. Mayo, by itself, is quite safe, even at room temperature, which is why you find it in the regular aisle at the store rather than in the fridge. It’s not sterile, which is an important distinction. Because eggs are one of the major ingredients, salmonella contamination is an big concern. However, mayo is an emulsion, and so has a very low water activity. Essentially, all of the water is tied up and unavailable for bacterial growth. So if salmonella bacteria are present, they can’t grow and make you sick. All that changes when you mix mayonnaise with something else - bread, meat, fish, potato salad, etc. Suddenly, you have a _potential_ salmonella source being plopped onto stuff the bacteria can eat and use to grow, and that plus time plus warm temperatures could mean real trouble. That’s the reasoning behind keeping mayo cold after it’s been opened. Even sticking a dirty knife in the mayo jar could theoretically starting things going bad. I don’t know if rates of salmonella contamination in commercial mayonnaise have changed in the last few decades or not. I know people seem to be a lot more paranoid about it these days. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [February 26, 2012, 8:12pm UTC](https://boards.straightdope.com/t/why-didnt-our-lunches-make-us-sick/614061/23 "2012-02-26T20:12:26Z")
> [@Alka\_Seltzer](#): > > Likewise, you can take food with you on a picnic without poisoning yourself. It takes a while for bacterial growth to be a problem. Usually, it’s not difficult to tell if food has gone off. If it smells bad, it is bad. This is not correct. Not all of the things that make food smell bad are harmful, and not all foodborne pathogens cause odour - The two things _may_ happen in parallel, or they may not. If it were true, pathogenic food poisoning would be uncommon. ---
**Author:** ![Chefguy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chefguy/32/138_2.png) [@Chefguy](https://boards.straightdope.com/u/Chefguy)\ **Post date:** [February 26, 2012, 8:13pm UTC](https://boards.straightdope.com/t/why-didnt-our-lunches-make-us-sick/614061/24 "2012-02-26T20:13:34Z")
> [@GiantRat](#): > > [snipped again] > > Tuna salad without mayo? How do you lube the tuna? Am I missing out on a secret tuna salad recipe? I often just use olive oil. ---
**Author:** ![Reply](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/reply/32/15952_2.png) [@Reply](https://boards.straightdope.com/u/Reply)\ **Post date:** [February 26, 2012, 8:29pm UTC](https://boards.straightdope.com/t/why-didnt-our-lunches-make-us-sick/614061/25 "2012-02-26T20:29:52Z")
> [@MsWhatsit](#): > > Well, it’s tuna and celery and soy sauce. I guess maybe not technically tuna salad. The kids like it, though. Interesting. Out of curiosity, have you or would you ever try vegenaise? ---
**Author:** ![Lynn\_Bodoni](https://avatars.discourse-cdn.com/v4/letter/l/e47c2d/32.png) [@Lynn\_Bodoni](https://boards.straightdope.com/u/Lynn_Bodoni)\ **Post date:** [February 26, 2012, 8:30pm UTC](https://boards.straightdope.com/t/why-didnt-our-lunches-make-us-sick/614061/26 "2012-02-26T20:30:21Z")
> [@GiantRat](#): > > [snipped again] > > Tuna salad without mayo? How do you lube the tuna? Am I missing out on a secret tuna salad recipe? My mother was on Weight Watchers for most of my childhood, and she customarily made tuna “salad” with mustard, rather than mayo. To this day, I prefer a good glop of mustard and not much mayo in my tuna salad. ---
**Author:** ![Michael63129](https://avatars.discourse-cdn.com/v4/letter/m/3da27b/32.png) [@Michael63129](https://boards.straightdope.com/u/Michael63129)\ **Post date:** [February 26, 2012, 9:00pm UTC](https://boards.straightdope.com/t/why-didnt-our-lunches-make-us-sick/614061/27 "2012-02-26T21:00:47Z")
> [@Smeghead](#): > > I’m seeing a lot of not-quite-right information here about mayonnaise. > > Mayo, by itself, is quite safe, even at room temperature, which is why you find it in the regular aisle at the store rather than in the fridge. It’s not sterile, which is an important distinction. Because eggs are one of the major ingredients, salmonella contamination is an big concern. However, mayo is an emulsion, and so has a very low water activity. Essentially, all of the water is tied up and unavailable for bacterial growth. So if salmonella bacteria are present, they can’t grow and make you sick. > > All that changes when you mix mayonnaise with something else - bread, meat, fish, potato salad, etc. Suddenly, you have a _potential_ salmonella source being plopped onto stuff the bacteria can eat and use to grow, and that plus time plus warm temperatures could mean real trouble. That’s the reasoning behind keeping mayo cold after it’s been opened. Even sticking a dirty knife in the mayo jar could theoretically starting things going bad. > > I don’t know if rates of salmonella contamination in commercial mayonnaise have changed in the last few decades or not. I know people seem to be a lot more paranoid about it these days. I’m pretty sure they use pasteurized eggs ([source](http://www.chow.com/food-news/54481/will-mayonnaise-give-me-food-poisoning/)) when uncooked eggs are used in any product, including mayo. Even if they don’t, the chances of an egg being contaminated is actually [pretty low](http://www.incredibleegg.org/egg-facts/egg-safety/eggs-and-food-safety#2): > [@](#): > > Scientists estimate that, on average across the U.S., only 1 of every 20,000 eggs might contain the bacteria. So, the likelihood that an egg might contain Se is extremely small – 0.005% (five one-thousandths of one percent). At this rate, if you’re an average consumer, you might encounter a contaminated egg once every 84 years. (not that there aren’t [outbreaks](http://www.msnbc.msn.com/id/38741401/ns/health-food_safety/t/recall-expands-more-half-billion-eggs/#.T0qbI3lktkg) though) Also, as **Chefguy** pointed out, preservatives are widely used in lunch meats (I’d be more concerned about the [long-term health effects of processed meats](http://www.webmd.com/heart-disease/news/20100517/processed-meat-linked-to-heart-disease-risks), at least if it is red meat, than salmonella). A personal anecdote - when I was a kid, my mother would make milk shakes using raw eggs as an ingredient, and I never got sick from them. ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [February 26, 2012, 9:07pm UTC](https://boards.straightdope.com/t/why-didnt-our-lunches-make-us-sick/614061/28 "2012-02-26T21:07:53Z")
> [@Smeghead](#): > > All that changes when you mix mayonnaise with something else - bread, meat, fish, potato salad, etc. Suddenly, you have a _potential_ salmonella source being plopped onto stuff the bacteria can eat and use to grow, and that plus time plus warm temperatures could mean real trouble. That’s the reasoning behind keeping mayo cold after it’s been opened. Even sticking a dirty knife in the mayo jar could theoretically starting things going bad. I do not believe commercially prepared mayonaisse is a potential salmonella source. And Miracle Whip certainly is not. The other ingredients in a mayo based recipe have been shown to be the source of bacteria, not the mayo. Most foods harbor bacterial growth, usually on the surface, even when kept refrigerated. This would not be the case in home made mayo using fresh eggs though. But I think that is not very common for school lunches. ---
**Author:** ![Foggy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/foggy/32/1082_2.png) [@Foggy](https://boards.straightdope.com/u/Foggy)\ **Post date:** [February 26, 2012, 9:15pm UTC](https://boards.straightdope.com/t/why-didnt-our-lunches-make-us-sick/614061/29 "2012-02-26T21:15:05Z")
Damn it people, now I’m hungry. FWIW: Starting in 3rd grade I made my & my brother’s lunches, usually PB&J. No fruit, no pudding cup, no thermos, just one sandwich each. Eventually we got on the school lunch program and my dark days of tolling over hot PB&J were at an end. ---
**Author:** ![dracoi](https://avatars.discourse-cdn.com/v4/letter/d/90db22/32.png) [@dracoi](https://boards.straightdope.com/u/dracoi)\ **Post date:** [February 26, 2012, 9:15pm UTC](https://boards.straightdope.com/t/why-didnt-our-lunches-make-us-sick/614061/30 "2012-02-26T21:15:50Z")
> [@GiantRat](#): > > Tuna salad without mayo? How do you lube the tuna? Am I missing out on a secret tuna salad recipe? Sour cream here. Half the calories of mayo for the same volume and a much more interesting flavor. I’ll also go half sour cream and half mayo if I want a more traditional flavor. ---
**Author:** ![njtt](https://avatars.discourse-cdn.com/v4/letter/n/ecd19e/32.png) [@njtt](https://boards.straightdope.com/u/njtt)\ **Post date:** [February 26, 2012, 9:16pm UTC](https://boards.straightdope.com/t/why-didnt-our-lunches-make-us-sick/614061/31 "2012-02-26T21:16:02Z")
My parents didn’t even own a refrigerator until I was in my teens. A generation or so before, they had not even been invented. How do you think people survived back then?! ---
**Author:** ![Hairy\_Bob](https://avatars.discourse-cdn.com/v4/letter/h/ecc23a/32.png) [@Hairy\_Bob](https://boards.straightdope.com/u/Hairy_Bob)\ **Post date:** [February 26, 2012, 9:31pm UTC](https://boards.straightdope.com/t/why-didnt-our-lunches-make-us-sick/614061/32 "2012-02-26T21:31:02Z")
> [@GiantRat](#): > > [snipped again] > > Tuna salad without mayo? How do you lube the tuna? Am I missing out on a secret tuna salad recipe? Why, salad **cream** , of course! Vastly improves most savoury foodstuffs. Meat, fish, crackers with cheese, day old pizza, pretty much whatever you fancy really… ---
**Author:** ![Acsenray](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/acsenray/32/4519_2.png) [@Acsenray](https://boards.straightdope.com/u/Acsenray)\ **Post date:** [February 26, 2012, 9:32pm UTC](https://boards.straightdope.com/t/why-didnt-our-lunches-make-us-sick/614061/33 "2012-02-26T21:32:00Z")
> [@Tom\_Tildrum](#): > > Mayo has vinegar (i.e., a preservative) in it, doesn’t it? It _can_ have vinegar. The basic ingredients of mayonnaise are oil and eggs. Everything else is optional. ---
**Author:** ![Ferret\_Herder](https://avatars.discourse-cdn.com/v4/letter/f/e47774/32.png) [@Ferret\_Herder](https://boards.straightdope.com/u/Ferret_Herder)\ **Post date:** [February 26, 2012, 9:38pm UTC](https://boards.straightdope.com/t/why-didnt-our-lunches-make-us-sick/614061/34 "2012-02-26T21:38:47Z")
> [@Smeghead](#): > > Mayo, by itself, is quite safe, even at room temperature, which is why you find it in the regular aisle at the store rather than in the fridge. I’m pretty sure it’s there because it’s been pasteurized and vacuum sealed; it does say to refrigerate (whether MW or mayo) after opening the lid. You can find shelf-stable milk or tofu, canned veggies, all kinds of things that really should go in the fridge after the seal is broken. ---
**Author:** ![samclem](https://avatars.discourse-cdn.com/v4/letter/s/a9a28c/32.png) [@samclem](https://boards.straightdope.com/u/samclem)\ **Post date:** [February 26, 2012, 9:42pm UTC](https://boards.straightdope.com/t/why-didnt-our-lunches-make-us-sick/614061/35 "2012-02-26T21:42:20Z")
> [@njtt](#): > > My parents didn’t even own a refrigerator until I was in my teens. A generation or so before, they had not even been invented. How do you think people survived back then?! Probably because they had \* iceboxes\*. How old are you that your parents didn’t have a refrigerator? ---
**Author:** ![Acsenray](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/acsenray/32/4519_2.png) [@Acsenray](https://boards.straightdope.com/u/Acsenray)\ **Post date:** [February 26, 2012, 9:58pm UTC](https://boards.straightdope.com/t/why-didnt-our-lunches-make-us-sick/614061/36 "2012-02-26T21:58:16Z")
> [@samclem](#): > > Probably because they had \* iceboxes\*. Things like eggs and bread and cured meats and cheese were not commonly stored in iceboxes, I believe. ---
**Author:** ![SciFiSam](https://avatars.discourse-cdn.com/v4/letter/s/47e85d/32.png) [@SciFiSam](https://boards.straightdope.com/u/SciFiSam)\ **Post date:** [February 26, 2012, 10:32pm UTC](https://boards.straightdope.com/t/why-didnt-our-lunches-make-us-sick/614061/37 "2012-02-26T22:32:17Z")
> [@Acsenray](#): > > Things like eggs and bread and cured meats and cheese were not commonly stored in iceboxes, I believe. Eggs and bread don’t need to be stored in the fridge now, either. But I’m pretty sure people back then used pantries which are significantly cooler than normal room temperature. That’s what my flat in Slovakia in the 90s had - no fridge. And if people were too poor to have a pantry, then they were probably also too poor to have food in the house long enough for it to rot. ---
**Author:** ![njtt](https://avatars.discourse-cdn.com/v4/letter/n/ecd19e/32.png) [@njtt](https://boards.straightdope.com/u/njtt)\ **Post date:** [February 26, 2012, 11:26pm UTC](https://boards.straightdope.com/t/why-didnt-our-lunches-make-us-sick/614061/38 "2012-02-26T23:26:02Z")
> [@samclem](#): > > Probably because they had \* iceboxes\*. How old are you that your parents didn’t have a refrigerator? I just turned 60, and no we didn’t have an icebox either. Anyway, you won’t have to go very far back to find a time when no-one, or virtually no-one, had iceboxes either. People who live in poorer parts of the world, which are often hot - rural India, for instance - still do not have refrigerators or iceboxes. They may get food poisoning a little more often than suburban Americans, but they are not constantly suffering from it. _This question is just ethnocentrism. All current middle-class American customs are entirely rational and necessary: How could people possibly live differently from the way middle-class Americans live now?_ ---
**Author:** ![astro](https://avatars.discourse-cdn.com/v4/letter/a/9dc877/32.png) [@astro](https://boards.straightdope.com/u/astro)\ **Post date:** [February 26, 2012, 11:44pm UTC](https://boards.straightdope.com/t/why-didnt-our-lunches-make-us-sick/614061/39 "2012-02-26T23:44:25Z")
The large majority of “food poisoning due to spoiled food” stories I see are typically church socials or large family picnic and outdoor get together cooking scenarios where lots of homemade food has been prepared from scratch, often more than 24 hours in advance, and has gone up to a day or longer without adequate refrigeration. A sandwhich 6 -12 hours out from the fridge made with processed or anti-spoilage treated meat and commercially produced mayo etc. is not really the same scenario. ---
**Author:** ![Acsenray](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/acsenray/32/4519_2.png) [@Acsenray](https://boards.straightdope.com/u/Acsenray)\ **Post date:** [February 26, 2012, 11:58pm UTC](https://boards.straightdope.com/t/why-didnt-our-lunches-make-us-sick/614061/40 "2012-02-26T23:58:14Z")
Even less so with things like peanut butter and jelly, cheese, or fruit, whether fresh or canned. [Previous page](https://boards.straightdope.com/t/why-didnt-our-lunches-make-us-sick/614061.md?page=1) [Next page](https://boards.straightdope.com/t/why-didnt-our-lunches-make-us-sick/614061.md?page=3)