What makes people ill, and the rules that stop it

Take two chicken breasts. One is poached very gently, and a thermometer in its centre reads 150°F (65.6°C) and stays there for five minutes. The other is on a hot grill, and when you check it the centre reads 150°F too, on its way up. Same meat, same reading. By the tables the US regulator publishes for meat plants, the first breast has probably had enough heat to be safe, and nobody can say that about the second, because a reading is a moment and safety takes time.

That idea is what this lesson is built on. It explains why the US says 165°F for chicken and the UK says 70°C for 2 minutes, why a big pot of stew can make people ill the next day, why a fridge slows germs without killing them, and why the most famous piece of kitchen advice, don't wash your chicken, turned out to be about something else. It is also the first lesson in the course to handle raw meat, so it is where the kitchen routine that goes with raw meat is set up.

Where the germs are

The NHS lists the usual causes of food poisoning: food that is not cooked or reheated thoroughly, isn't stored correctly, is handled by someone who is ill or hasn't washed their hands, or is eaten after its use-by date.³¹ Every one of those is about time, temperature or hands, which is what this lesson covers. Raw chicken is the example this lesson keeps coming back to. The CDC says raw chicken "can be contaminated with Campylobacter, Salmonella, or Clostridium perfringens germs", and that "1 in 25 packages of chicken at the grocery store are contaminated with Salmonella."¹ In the UK, the Food Standards Agency (FSA) calls Campylobacter "the main cause of bacterial food poisoning in the UK", and says it "has a low infective dose", meaning it takes few germs to make you ill.²

Where the germs sit inside the meat matters as much as whether they are there. The FSA's cooking page draws the line. Whole cuts of beef and lamb, such as steaks and joints, "only ever have bacteria on the outside surface of the meat", so they "can be served pink in the middle according to taste" once the outside is cooked. But "Poultry (such as chicken, turkey, duck, and game birds) and pork can have bacteria all the way through the meat," so those need cooking all the way through, and so does anything minced, because mincing spreads what was on the surface into the middle.³¹² Hold on to that. It's why a rare steak and a rare burger are different questions, which lesson 7 takes up.

How many people get ill is a figure with dates on it. The CDC's current estimate, published in 2025 from 2019 data, covers seven major germs and counts 9.9 million illnesses in the US that year, with 53,300 hospital stays and 931 deaths; norovirus causes the most illnesses and Salmonella the most deaths.⁴ In the UK, the FSA puts foodborne disease at about 2.4 million cases a year, a figure due to be replaced by new models by early 2027.⁵

Time plus temperature

Here's the principle. Heat kills bacteria at a rate, not a switch. At a given temperature, a fixed fraction of the germs dies in each stretch of time, so the count falls tenfold, then tenfold again, and so on for as long as the food stays there. Food scientists count kills in those tenfold steps, called log reductions. A 7-log reduction is ten million to one: start with ten million Salmonella and one is left.

Douglas Baldwin's sous vide guide gives one measured rate: at 140°F (60°C), Salmonella in minced beef "is reduced by a factor ten every 5.48 minutes".⁶ Hold it there 11 minutes and you have a hundredfold kill; hold it 22 and you have ten thousandfold. Heat it hotter and each tenfold step comes faster. Published rates vary with the food and the study, which is why regulators publish tables rather than one rate. But the shape is always the same: a lower temperature does the same job as a higher one if you hold it longer.

The chart draws those FSIS figures for chicken, with the UK's own time and temperature pairs laid over them.

The lines are FSIS's Table 3 (7-log Salmonella, chicken, 1% and 12% fat).⁷ The squares are the FSA's list: 60°C for 45 minutes, 65°C for 10, 70°C for 2, 75°C for 30 seconds, 80°C for 6 seconds.³ Time is on a log scale, so each gridline up is ten times longer. The lines stop where FSIS's time reaches zero.

Look at where the squares sit. Every UK pair sits above the US lines. At 65°C (149°F) the FSA asks for 10 minutes; one degree Fahrenheit hotter, at 150°F, the FSIS chicken table needs 2.7 to 4.2. The two lists are not measuring the same thing. FSIS's table is a 7-log kill of Salmonella in chicken. The FSA's is a rule for "the middle of the food", any food, and its burger guidance says 70°C for 2 minutes gives a "six-log" reduction "in harmful bacteria" without naming one germ.¹² A six-log kill is a smaller one than FSIS's seven, so the log count doesn't explain why the UK asks for more time; it points the other way. The pages read here don't say how the UK pairs were worked out, so this course does not explain the gap. What they share is the shape. Both are a curve of time against temperature, and the FDA's code for restaurants has the same curve for a beef roast: 112 minutes at 130°F (54.4°C) gives the same kill as 4 minutes at 145°F.⁸

So 165°F (74°C) held for no time and 70°C held for 2 minutes are the same kind of rule: a point on a curve, chosen so a home cook can check it.

Why a reading is not a guarantee

Now the two breasts from the start. The poached one sat at 150°F (65.6°C) for five minutes, and the FSIS table asks for 2.7 minutes (lean) to 4.2 minutes (12% fat) at that temperature.⁷ If the reading was right and the centre stayed there, that breast got its 7-log kill.

The grilled one passed 150°F on the way up. It did not stay anywhere. If you took it off at that reading, the centre might climb a little more and then cool, and there's no way to know from one reading how long it spent at any temperature. It has not met the table and it has not met the consumer rule.

There is a second wrinkle. Lesson 2 gave FSIS's figure for how far a food thermometer can be off: most read "within 2 to 4 degrees F".⁹ So a reading of 150°F could be a centre at 146°F, next door to 145°F, where the table wants 8.4 to 13 minutes.⁷ A rule set at the instant-kill point, 165°F, has room for that error built in.

Cook: the thermometer, or the cues

The two countries agree on the curve and differ on how a home cook should check it.

The US says use a thermometer. The FSIS chart gives the numbers: poultry 165°F (73.9°C), minced meat 160°F (71.1°C), steaks, chops and roasts of beef, pork, veal and lamb 145°F (62.8°C) "and allow to rest for at least 3 minutes".¹⁰ The CDC says "You can't tell if food is safely cooked by checking its color and texture (except for seafood)."¹¹ FSIS gives the reason for burgers: "Ground beef may turn brown before it has reached a temperature at which bacteria are destroyed."⁹

The UK accepts either. The FSA's cooking page tells you to check food is cooked and "use visual cues, such as making sure the food is steaming hot", and to "consider using a food thermometer". Its detailed advice gives the thermometer first and then the cues, which it introduces with "If you don't have a food thermometer". For chicken the cue is to "cut into the thickest part and check there is no pink meat left and that juices run clear".³ So the real difference is that the UK treats those cues as a sound check, and the CDC says colour and texture can't tell you. The cues aren't careless, though: they check the right place, the thickest part, which lesson 2 showed is the last to heat. Where the FSA thinks colour is not enough, it says so. Its guidance to restaurants says "The colour of a beef burger cannot be used as the sole indication of safe cooking."¹²

Pork is where the two sets of advice come apart most visibly. The US has allowed whole cuts of pork at 145°F with a rest, pink in the middle, since 2011; the UK says pork must be cooked through with no pink.¹⁰³ This course's reading, from its research, is that this is a difference in how cautiously each agency phrases advice for the public rather than a disagreement about germs, and the FSA's own list is the evidence: it accepts 60°C (140°F) for 45 minutes, which is below 145°F.³ Lesson 7 takes pork and burgers further. Whichever country you are in, follow its rule, and if you live somewhere else, follow your own regulator; these two are shown side by side because both were read.

Clean, separate, cook, chill

The US calls the framework four steps: clean, separate, cook, chill. The UK calls it the 4Cs: cleaning, chilling, cooking and avoiding cross-contamination.¹³² Same content. Cross-contamination is germs moving from something raw to something that won't be cooked again: from chicken to your hands, from your hands to the tap, from the tap to the lettuce.

Cleaning starts with your hands: soap and water for at least 20 seconds, which FSIS says is humming "Happy Birthday" twice.¹⁴ foodsafety.gov says plain soap works and to "skip the antibacterial soap".¹³ For boards and utensils, FSIS gives a home sanitiser: "one tablespoon of unscented liquid chlorine bleach with a gallon of water".¹⁴ That is about 15 ml in 3.8 litres. It also says why the cleaning matters: "Campylobacter can survive in your kitchen for up to 4 hours and Salmonella can last for up to 32 hours."¹⁴

Separating is where lesson 1's board comes back. FSIS says one board for produce and bread and a separate one for raw meat, poultry and seafood.¹⁵ If you have one board, the FSA's instruction is to "prepare vegetables and fruit first followed by raw meat, fish or poultry last".¹⁵ In the fridge, the CDC and the FSA both say raw chicken goes on the bottom shelf,¹²⁵ and FSIS says raw meat, poultry and seafood should be sealed or wrapped "to prevent raw juices from contaminating other foods."¹⁶

A salad and roast chicken thighs, with one board

Here's that worked through for a dinner of green salad and roast chicken thighs with carrots, on one board and one knife.

1. Clear the sink and the draining board, and wash your hands.
2. Wash the salad leaves and cut everything that won't be cooked: the cucumber, the tomatoes, the dressing's garlic. The salad goes into its bowl, covered, well away from where the chicken will be.
3. Cut the carrots for the tray. They will be cooked, but doing them now keeps the board clean for longer.
4. Now the chicken. Open the pack over the roasting tray. If there's something on a thigh you want off, pat it with a paper towel and bin the towel. Trim on the board if you need to. Season in the tray.

6. Cook the thighs to 165°F in the thickest part (US), or until steaming hot with no pink and clear juices (UK).
7. Serve the cooked chicken onto a clean plate. The tray, board and tongs that held it raw count as raw until they are washed.

The hand-washing is the regulators' advice; the order of steps 5 and 7, and the list of things to wipe, are this course's application of the separate principle. The USDA study in the next section is the reason for them.

Washing raw chicken

This is the piece of food-safety advice people argue about most, and it is worth getting right, because the research behind it says something more useful than "don't".

A lot of cooks wash chicken. In a 2015 national US web survey of 1,504 people, "Nearly 70% of consumers reported washing or rinsing raw poultry before cooking it".¹⁷ The advice from every regulator read is the same in direction. FSIS says washing raw poultry "is not recommended as the safest method."¹⁴ The FSA says "never wash chicken/poultry", because washing "can spread campylobacter by splashing it onto hands, work surfaces, clothing and cooking equipment."² The CDC says raw chicken "doesn't need to be washed first", and then adds: "If you choose to wash chicken, do so as safely as possible".¹¹

In 2019 the USDA reported the first results of a study, published in full in 2022, of 300 people who said they usually washed their chicken. About half were first sent the USDA's messages advising against it. Then everyone was filmed cooking chicken thighs, dosed with a harmless strain of E. coli the researchers could trace, and making a salad, and the researchers watched what each person actually did.¹⁹

So the salad was reached by washers and non-washers alike, and washing added a contaminated sink. The study's authors drew the conclusion themselves. The high levels of the E. coli strain they tracked in the sink and on the lettuce, they wrote, "suggest that microbes transferred to the sink from the chicken, packaging, or contaminated hands are a larger cause for concern than is splashing contaminated chicken fluids onto the counter." And they recommended changing the frame of the "don't wash your poultry" message "to instead focus on preventing contamination of sinks and continuing to emphasize the importance of hand washing and cleaning and sanitizing surfaces."¹⁹ That is the course's question at work. What is "don't wash chicken" protecting? The sink and the salad. The researchers behind the USDA's own study moved the message to the thing it protects.

Why cooks wash, in their own words

The reasons are real, and they are not ignorance. Carolyn Desalu, writing for Food52 in 2022, grew up in a Belizean and Nigerian family where, as she puts it, "washing meat is the start to well-prepared food". "To us, it's a ritual, a mandate. We care equally about cleaning, eating, and communing." Her own method: "a running water rinse, then soaking in a large bowl of cold water plus lemon juice and/or vinegar for a few minutes to 'wash' away the germs". Her 83-year-old cousin Bobbi remembers buying meat at a Belize City market where "you saw someone handling your meat with their bare hands. That was more than enough reason to wash it at home." The market gave way to supermarkets, and it "never changed her stance on meat washing." Bobbi rubs each piece with cut lemons, seasons it, and then cleans her sink and counters "with the leftover lemons to avoid cross contamination".²⁰

Julius Jackson, a chef and cookbook author in St. Thomas in the US Virgin Islands, told her: "Everyone I saw in the kitchen, including my mother, cleaned their meat before seasoning." His mother used "warm water and lemons or vinegar". He gives history as part of the reason: "The United States Virgin Islands was a port for slavery. Food for [slaves] were leftovers kept in dirty buckets." His own method is practical about the risk: "Use a really large bowl because it prevents splashing and try to avoid washing in your sink."²⁰

Researchers who've asked cooks find the same range of reasons. Drexel University's Jennifer Quinlan and colleagues found that home cooks wash because of a "desire to control the process of preparing food, have a lack of trust in chicken processing and/or the habitual nature of the behavior."²¹ In Philadelphia focus groups, washing with "acidic solutions" was found among African American and Hispanic participants; the authors caution that their small sample "cannot be extrapolated".²² Desalu's piece and those studies are the only accounts of the practice this course has read, so this lesson names no tradition beyond the ones they name.

Does an acid wash kill the germs? A 2018 lab study by the same Drexel group washed chicken in 10% lemon juice or 10% vinegar and found that live Salmonella stayed on the chicken and in the wash water, calling it "an inefficient method for removing pathogens".²³ The limits matter: the chicken was deliberately loaded with a very high dose of Salmonella, and 10% is a diluted solution, not neat juice. But nothing read here suggests a lemon wash makes chicken safe. Cooking does that.

So the microbiology is settled, and whether to keep washing is the cook's call, as the title of the USDA's own 2019 release says: "Our Science, Your Choice."¹⁸ If you are going to wash, here's the version that does least harm. The steps come from the CDC, the USDA, FSIS, Jackson and Chapman, except the second, which is this course's application of them:

• Make the salad and anything else eaten raw first, as in the order of work above.¹⁸
• Clear the sink and draining board before you start.
• Wash in a large bowl rather than under the tap, as Jackson does, or if you use the tap, "Run the water gently over the chicken to reduce splashing".¹²⁰
• Treat the wash water, lemon or vinegar included, as raw chicken juice. Food scientist Benjamin Chapman told Desalu to "Look at the liquid like it's a pathogen", and FSIS's advice for a soak is to "Carefully pour out the soak and do not reuse it."²⁰¹⁴
• Clean and then sanitise the sink afterwards, and wash your hands for 20 seconds.¹ Chapman says "Bleach-based solutions are the safest for cleaning", and of vinegar: "We don't have good data that proves vinegar kills what's in your sink. It does [help], but lemons and vinegar don't do enough."²⁰

If the reason is slime, the USDA's alternative is to "pat the area with a damp paper towel and immediately wash your hands."¹⁸ If the lemon or vinegar is there for flavour, it can stay as a marinade step; it just isn't a safety step. Desalu ends her piece still washing, and planning to teach her son, but with one change: she'll "update my family tradition by sanitizing with a bleach-based solution instead of vinegar because tradition can change a little."²⁰

Chill: fridges, cooling and leftovers

Bacteria grow fastest in the temperatures between the fridge and the plate. FSIS says they "grow most rapidly in the range of temperatures between 40 °F and 140 °F, doubling in number in as little as 20 minutes."²⁴ The UK draws that danger zone at 8 to 63°C.³ The fridge figures differ by about a degree: the US says 40°F (4°C) or below;¹³ the FSA says "between 0 and 5°C".²⁵

A fridge slows germs. It does not kill them, and freezing does not either: "Freezing does not destroy harmful germs, but it does keep food safe until you can cook it."¹³ And one germ grows in the cold. FSIS notes that "some bacteria such as Listeria monocytogenes thrive at cold temperatures, and if present, will multiply in the refrigerator over time".¹⁶ That is why the higher-risk section below is about chilled foods.

Cooling a big pot

Cooling fails for the reason heating does. Lesson 2 showed heat entering from the surface, with the centre last. A big pot of stew loses heat the same way in reverse, so its middle can sit in the danger zone for hours while the edges are cold. The answer is to divide it, and here the two countries agree. FSIS: "A big pot of soup, for example, will take a long time to cool", so use shallow containers.²⁶ The FSA: "To cool food quickly, divide food into smaller portions in containers or freezer bags before putting in the fridge or freezer."²⁵ The FDA's 2026 code for restaurants added a new benchmark: food spread "at a depth of no more than 2 inches", about 5 cm.⁸ Lesson 10 explains which germ this rule is aimed at.

Where the two countries differ is the fridge door. FSIS says "Hot food can be placed directly in the refrigerator or be rapidly chilled in an ice or cold water bath before refrigerating."²⁶ The FSA says "Don't place hot or warm food in your fridge. Instead, cool cooked food at room temperature and place in the fridge within one to two hours."²⁵ Both want food cold fast. The US answer lets the cooling happen inside the fridge; the UK answer does it outside, against a deadline. Neither page read gives its reasoning, so this course will not guess at it.

The clock on the counter and in the fridge

The US rule for food out of the fridge is 2 hours, or 1 hour "If the temperature is above 90 °F" (32°C).²⁴ The FSA allows chilled food out during preparation for "a maximum of four hours" and wants cooked food cooled and in the fridge within one to two hours.²⁵ For ready-to-eat food, its Listeria page adds a hot-weather version: eat it "within 4 hours or within 2 hours on a very warm day" of taking it out of the fridge.²⁸

Leftovers: FSIS says "3 to 4 days" in the fridge.²⁶ The FSA says "Eat leftovers within 48 hours or freeze them".³ Reheating: FSIS says to 165°F, with "sauces, soups and gravies" brought "to a rolling boil".²⁶ The FSA says steaming hot, and adds a rule the FSIS pages don't give: "you should only ever reheat once".³

Thawing: FSIS gives three safe ways, "in the refrigerator, in cold water, and in the microwave", with the cold water changed every 30 minutes, and says cooking from frozen is safe too.²⁷ After thawing in the fridge, it says, poultry, mince and seafood keep "an additional day or two before cooking", and red meat cuts 3 to 5 days.²⁷ The FSA lists the fridge, or the microwave's defrost setting "directly before cooking", and says to use food "within 24 hours after it's been fully defrosted".²⁵ Neither lists the counter. FSIS says never thaw there, because the outside can sit in the danger zone while the middle is still frozen,²⁷ and the FSA calls the fridge "the safest way to defrost food".²⁵ Lesson 12 comes back to freezing and thawing when you plan a week.

Your nose, and the dates

Most people check doubtful food by smelling it, and the reason that doesn't work is worth knowing. FSIS says there are "two completely different families of bacteria". Spoilage bacteria make food "develop unpleasant odors, tastes, and textures". Pathogens, the ones that make you ill, "do not generally affect the taste, smell, or appearance of a food. In other words, one cannot tell that a pathogen is present."¹⁶ Its conclusion has two halves: "Food that has been left too long on the counter may be dangerous to eat, but could look fine. Food that has been stored too long in the refrigerator or freezer may be of lessened quality, but most likely would not make anyone sick." The exception it adds is Listeria, which grows in the cold.¹⁶ And the fridge still has a clock: the same agency's rule for leftovers is 3 to 4 days.²⁶ The FSA says the same about looks and smell: "You cannot see, smell or taste bacteria that causes foodborne illness".²⁸

So a bad smell tells you about quality, and a good one tells you nothing about safety. The UK's date labels are built on that distinction. A use-by date tells you "when the food is no longer safe to eat" and is required on foods that go off quickly, like meat products and ready-to-eat salads. A best-before date "tells you when the food might start to reduce in quality", and only after a best-before date does the FSA say "you can use sight, taste or smell to decide".²⁹ Food can be eaten after its use-by date if it was cooked or frozen on or before it.²⁹

The US works differently. FSIS says that "Except for infant formula, dates are not an indicator of the product's safety and are not required by Federal law", and that past the date a product "should still be safe and wholesome if handled properly until the time spoilage is evident."³⁰ So in the US, for handled-properly food, the date is the maker's quality estimate, and the safety tools are the time and temperature rules above.

Cooking for someone at higher risk

For most healthy adults food poisoning is unpleasant and short; the NHS calls it "rarely serious".³¹ For some people it is more dangerous. The CDC lists pregnant women, newborns, people 65 and older and people with a weakened immune system as at higher risk from Listeria.³² The FSA lists pregnant women and their unborn babies, people with weakened immune systems, and older people, whose risk "increases with age".²⁸ Listeria is the reason for most of the food rules in this section, because it grows in the fridge and, in the FSA's words, "it is more common in ready-to-eat foods".²⁸ The CDC says that "1 in 4 pregnant women who get this illness lose their pregnancy or their baby shortly after birth", though the infection itself is rare.³²

The lists of foods are similar in the two countries and differ in detail.

• The US (CDC). For people in these groups: avoid unheated deli meat, cold cuts and hot dogs, or reheat them "to 165°F or until steaming hot"; avoid refrigerated pâté and refrigerated smoked fish; avoid unpasteurised milk and cheese made from it, unheated queso fresco-type cheeses, raw or lightly cooked sprouts, ready-made deli salads, and cut melon left out more than 2 hours or kept in the fridge more than a week.³²
• The UK (NHS and FSA). In pregnancy: mould-ripened and soft blue cheeses must be "thoroughly cooked"; cold cured meats such as salami "should be cooked until steaming hot"; cold-smoked fish such as smoked salmon "must be cooked until steaming hot"; pre-cooked meats, pâté and pre-packed sandwiches kept chilled and eaten before the use-by date.³³ The FSA advises pregnant women and people with weakened immunity to avoid ready-to-eat cold-smoked or cured fish, and says "cooking will kill any listeria that may be present".²⁸

The one thing the two countries share: heating these foods until steaming hot deals with the Listeria risk. Burgers, raw flour and runny eggs have rules for these groups too, and they are taught in lessons 7, 11 and 5. This course is not a pregnancy diet guide; a midwife or doctor is the person for that.

This callout appears in the lessons that cook eggs and meat, so that anyone arriving there first meets it.

Allergens: a different kind of hazard

Everything so far is about germs, which cooking kills. Food allergy is different, and the difference is the reason it has a section here even though this course does not teach managing an allergy.

The US names nine major food allergens: milk, eggs, fish, crustacean shellfish, tree nuts, peanuts, wheat, soybeans and, since 2023, sesame.³⁴ UK food law names fourteen: celery, cereals containing gluten, crustaceans, eggs, fish, lupin, milk, molluscs, mustard, peanuts, sesame, soybeans, sulphur dioxide and sulphites, and tree nuts.³⁵ The FDA's warning is blunt: "a mild allergic reaction does not always mean the allergy is mild."³⁴

Two facts change what a cook does. First, heat does not help. The FSA: "heating does not remove the allergenic potential of proteins in food unless they are completely hydrolysed, and heating temperatures in the kitchen will not do this."³⁵ Second, the amounts are tiny. If you've served someone a food they can't eat, "just taking it off their plate is not enough. This is because an extremely small amount can be enough to cause an allergic reaction."³⁵ The FDA's name for an allergen getting into food by accident is cross-contact: "Cross-contact occurs when a major food allergen, which is not an intentional ingredient in a food, is unintentionally introduced into that food."⁸ The FSA calls it cross-contamination. Either way it is the separate step again, with the difference that cooking afterwards does not fix it.

When you cook for someone with an allergy, the FSA's steps are to ask them (or a child's parents or carers) what they can and cannot eat, keep allergens separate, check the labels of sauces, dressings and desserts, keep a note or the packet of what went in, and avoid extra toppings. It adds that your guest "will have the best understanding of their specific allergy".³⁵ Lesson 12's project asks how you handled it if you cook for anyone with one.

The two countries side by side

This is the course's reference table. Later lessons point back to it.

The rows come from the pages cited above, plus the FSA's fact checker for eggs and rice.^{310132425262728293033}

Hazards later in the course

Some hazards belong to particular foods and are taught where the food is cooked: garlic in oil (lesson 3), runny and raw eggs (5), pork, rolled joints, burgers and kebabs (7), slow cookers (8), rice and red kidney beans (9), big pots of stock and stew cooling slowly (10), raw flour and dough (11), and freezing, thawing and home canning (12).

What people get wrong

"Wash chicken to make it safe." Washing doesn't make it safer and, with lemon or vinegar, still leaves live Salmonella on the chicken and in the water.²³ Cooking makes it safe. The bigger risk is the sink and your hands.¹⁹

"You can tell it's done by the colour." For burgers, neither country says so: FSIS says ground beef can brown before it's safe, and the FSA says a burger's colour can't be the only check.⁹¹² The UK's cues for chicken aren't colour alone either. They're steaming hot, no pink at the thickest part and clear juices, and the FSA offers them for when you don't have a thermometer.³

"Hot food will ruin the fridge" and "never leave food out to cool." These are the two countries' versions of one goal, cooling fast. FSIS says hot food may go in; the FSA says cool it first but have it in the fridge within one to two hours.²⁶²⁵

"Freezing kills the germs." It keeps food safe until you cook it, and does not destroy the germs.¹³

"If it smells fine, it's fine." The germs that make you ill generally don't change the smell.¹⁶

"48 million Americans get food poisoning every year." That was the CDC's 2011 estimate, covering all causes. Its 2025 estimate covers seven major germs and counts 9.9 million. The CDC says the two "cannot meaningfully" be compared, so the smaller number is not a fall, and it says the older estimates "were not wrong".⁴

Practice

Connections

Lesson 1 gave you the separate board, and this lesson gave you the routine for when you have only one. Lesson 2 gave you the thermometer and the centre that lags, and both did the work here: the thermometer goes in the thickest part because that's the last place to reach the temperature, and a big pot cools slowly for the same reason. Nutrition: The Evidence's first lesson, "What a food study can tell you", explains what an observational study like the USDA's can and cannot show: the researchers assigned the messages but not the washing, so the comparison between washers and non-washers is not a controlled trial of washing.

Lesson 5 cooks the first animal food of the course, eggs, and it is where the two countries' rules change what's on your plate. Every lesson after it that cooks meat, grains or stock uses this lesson's table.

Go deeper

• FSA, Cooking your food. Read in full for this course. Short, and the clearest statement of the UK's approach: the equivalence list, the visual cues and which meats can be pink.
• FSIS, Cooking Guideline for Meat and Poultry Products (Revised Appendix A), December 2021. Read in full. Written for meat plants, not kitchens, but its tables for beef, chicken and turkey are the whole of time plus temperature, and you can now read them.
• Carolyn Desalu, "Washing meat is cultural, yet mandatory", Food52, republished by Salon, 2022. Read in full (the Salon copy). The practice described by the people who keep it, with a food-safety scientist and an editor who disagree given their say.
• CDC, Preventing Listeria Infection. Read in full. A two-column table of foods to avoid and what to choose instead, for anyone cooking for someone at higher risk.

Sources

1. CDC, "Chicken and Food Poisoning", reviewed 29 April 2024, read through a 2026 Internet Archive capture . Read level: full. Supports: the three germs, 1 in 25 packages, the bottom shelf, and the safe-washing steps including running water gently and sanitising the sink.
2. FSA, "Campylobacter", GOV.UK, published 9 January 2018, https://www.gov.uk/government/publications/campylobacter/campylobacter . Read level: full. Supports: the main bacterial cause, low infective dose, splashing, "never wash chicken/poultry", and the 4Cs.
3. FSA, "Cooking your food", GOV.UK, published 18 December 2017, https://www.gov.uk/government/publications/cooking-your-food/cooking-your-food . Read level: full. Supports: whole cuts against poultry, pork and mince, the equivalence list, the visual cues and "If you don't have a food thermometer" (Stage 4 note, lesson 4), the 8 to 63°C danger zone, leftovers within 48 hours, reheat once. The reading of the pork difference as one of phrasing is this course's, from its research (SOURCES D3d), as the body says.
4. CDC, "Estimates: Burden of Foodborne Illness in the United States", reviewed 19 March 2025, and "Burden of Foodborne Illness: Questions and Answers", read through Internet Archive captures; E. J. Scallan Walter and colleagues, "Foodborne Illness Acquired in the United States: Major Pathogens, 2019", Emerging Infectious Diseases 31(4), April 2025 . Read level: full. Supports: 9.9 million, 53,300, 931, norovirus and Salmonella, the 48 million comparison.
5. FSA, "Foodborne pathogens" research page (Internet Archive, June 2026 capture; read in part) and board paper "FSA 26/03/07 Foodborne Disease Update", published 25 June 2026 . Read level: partial and full. Supports: about 2.4 million cases and new models by early 2027.
6. Douglas Baldwin, "A Practical Guide to Sous Vide Cooking", version 0.4k, https://douglasbaldwin.com/sous-vide.html . Read level: full. Supports: the tenfold reduction every 5.48 minutes at 140°F.
7. USDA FSIS, "FSIS Cooking Guideline for Meat and Poultry Products (Revised Appendix A)", December 2021, FSIS-GD-2021-14, read from the North Carolina Department of Agriculture's copy . Read level: full; the tables read from their images. Supports: Table 3's chicken times drawn in the chart and quoted in the body, and that the guideline is written for meat establishments. The turkey times in the quiz are Table 4.
8. US FDA, Food Code 2026, released 17 September 2026 . Read level: the PDF searched in full for the sections used. Supports: the roast table (112 minutes at 130°F, 4 minutes at 145°F), the 2-inch cooling depth, and the definition of cross-contact in Annex 3.
9. USDA FSIS, "Food Thermometers", last updated 21 March 2025, and "Doneness Versus Safety", last updated 10 July 2024, read through Internet Archive captures . Read level: full. Supports: accuracy within 2 to 4°F, and ground beef browning before it's safe.
10. USDA FSIS, "Safe Minimum Internal Temperature Chart", last updated 14 April 2025, read through the Internet Archive's September 2026 capture . Read level: full. Supports: 165°F, 160°F, 145°F with a 3-minute rest. The 2011 date of the pork change, and the agency's statement that pork cooked to 145°F with its rest "may still be pink but is safe to eat", are from CIDRAP's report of it, read in full (SOURCES D3d; Stage 4 note, lesson 4).
11. CDC, "Preventing Food Poisoning", reviewed 24 November 2025, read through a 2026 Internet Archive capture . Read level: full. Supports: colour and texture, "doesn't need to be washed first", "If you choose to wash chicken".
12. FSA, "Less than thoroughly cooked beef burgers: guidance for food businesses", GOV.UK, version of 22 May 2023 . Read level: full. Supports: the colour sentence.
13. foodsafety.gov, "4 Steps to Food Safety", read through the Internet Archive's September 2026 capture . Read level: full. Supports: the four steps, plain soap, 40°F (4°C), freezing does not destroy germs.
14. USDA FSIS, "Washing Food: Does it Promote Food Safety?", last updated 7 February 2024, read through the Internet Archive's September 2026 capture . Read level: full. Supports: "not recommended as the safest method", survival times, the bleach sanitiser, hand washing, and pouring out a soak (Stage 4 note, lesson 4).
15. FSA, "Why avoiding cross-contamination is important", GOV.UK, published 18 December 2017; USDA FSIS, "Cutting Boards", last updated 27 August 2024 . Read level: full. Supports: vegetables first and raw meat last on one board; separate boards.
16. USDA FSIS, "Refrigeration and Food Safety", last updated 23 March 2015, read through the Internet Archive's 23 September 2026 capture . Read level: full, directly. Supports: the two families of bacteria, pathogens not changing smell, both halves of its quality-against-safety conclusion, Listeria growing in the fridge, wrapping raw meat.
17. K. M. Kosa and colleagues, Journal of Food Protection 78(1), 2015, 180 to 186, PMID 25581194 . Read level: abstract. Supports: nearly 70% of 1,504 respondents.
18. USDA, "Washing Raw Poultry: Our Science, Your Choice", press release, 20 August 2019, read through the Internet Archive . Read level: full; the study's own report was not read. Supports: 60%, 14%, 26% and 31%, salad first, the damp paper towel.
19. E. T. Shumaker and colleagues, "Observational Study of the Impact of a Food Safety Intervention on Consumer Poultry Washing", Journal of Food Protection 85(4), 2022, 615 to 625, PMID 35051277 . Read level: abstract. Supports: the study's design (300 people who reported washing, about half sent USDA messages, chicken thighs carrying a traceable harmless E. coli), the lettuce figures for both groups, the sink and hands sentence and the recommendation to reframe the message (Stage 4 note, lesson 4).
20. Carolyn Desalu, "Washing meat is cultural, yet mandatory", Food52, republished by Salon, 7 August 2022 . Read level: full, the Salon copy. Supports: her account and her conclusion, her cousin's, Julius Jackson's, and Benjamin Chapman's comments (the fuller Chapman and Jackson passages and Desalu's conclusion: Stage 4 note, lesson 4).
21. Drexel University News, "Don't Wash Your Chicken: It's Risky, It's Unnecessary and There's a Better Way!", 30 August 2022 . Read level: full, rechecked directly. Supports: Quinlan's three reasons.
22. S. C. Henley, S. E. Stein and J. J. Quinlan, "Identification of unique food handling practices that could represent food safety risks for minority consumers", Journal of Food Protection 75(11), 2012, 2050 to 2054, PMID 23127716 . Read level: abstract. Supports: acidic solutions among African American and Hispanic participants; "cannot be extrapolated".
23. S. C. Henley, N. Launchi and J. J. Quinlan, "Survival of Salmonella on raw poultry exposed to 10% lemon juice and vinegar washes", Food Control, December 2018 . Read level: abstract. Supports: the 10% lemon juice and 10% vinegar washes, Salmonella surviving on the chicken and in the water, and the quoted phrase.
24. USDA FSIS, "Danger Zone (40°F - 140°F)", last updated 28 June 2023, read through a 2026 Internet Archive capture . Read level: full. Supports: doubling in as little as 20 minutes, the 2-hour and 1-hour rules.
25. FSA, "How to chill, freeze and defrost food safely", GOV.UK, published 18 December 2017 . Read level: full. Supports: 0 to 5°C, four hours, cooling within one to two hours, dividing food into smaller portions, the bottom shelf, thawing methods, the fridge as the safest way to defrost, and 24 hours after defrosting (Stage 4 note, lesson 4).
26. USDA FSIS, "Leftovers and Food Safety", last updated 31 July 2020, read through the Internet Archive . Read level: full. Supports: shallow containers, hot food straight in, 3 to 4 days, reheating to 165°F and a rolling boil.
27. USDA FSIS, "The Big Thaw: Safe Defrosting Methods", last updated 15 June 2013, read through the Internet Archive . Read level: full. Supports: the three methods, water changed every 30 minutes, cooking from frozen, the counter, a day or two after fridge thawing for seafood.
28. FSA, "Listeria", GOV.UK, https://www.gov.uk/government/publications/listeria/listeria . Read level: full, directly. Supports: the higher-risk groups, "more common in ready-to-eat foods", "You cannot see, smell or taste bacteria", the smoked fish advice, 2 hours on a very warm day for ready-to-eat food.
29. FSA, "Understanding food labelling: Best before and use-by dates", GOV.UK . Read level: full. Supports: the two dates and what each means.
30. USDA FSIS, "Food Product Dating", read through the Internet Archive's September 2026 capture . Read level: full. Supports: the quoted sentences on US dates.
31. NHS, "Food poisoning", last reviewed 19 December 2024, https://www.nhs.uk/conditions/food-poisoning/ . Read level: full. Supports: the usual causes, "rarely serious".
32. CDC, "Preventing Listeria Infection", dated 31 January 2025, read through the Internet Archive's August 2026 capture; CDC, "People at Increased Risk for Listeria Infection", reviewed 24 September 2025 . Read level: full. Supports: the groups, the list of foods, reheating to 165°F, and 1 in 4 pregnancies.
33. NHS, "Foods to avoid in pregnancy", last reviewed 15 June 2026, https://www.nhs.uk/pregnancy/keeping-well/foods-to-avoid/ ; FSA, "Home food fact checker", GOV.UK, updated 21 August 2026 . Read level: full. Supports: the UK pregnancy food list, the eggs row and the rice row.
34. US FDA, "Food Allergies: What You Need to Know", content current as of 16 August 2024 . Read level: full, directly. Supports: the nine major allergens, sesame from 2023, the mild reaction sentence.
35. FSA, "Food allergy and intolerance advice for consumers", GOV.UK, updated 7 August 2026 . Read level: full, directly. Supports: the fourteen allergens, heating, "just taking it off their plate", and the steps for cooking for a guest.