This is particularly concerning for pregnant women, older adults, and people with weakened immune systems.
Listeria infection can cause fever, muscle aches, headache, nausea, and diarrhea. In vulnerable individuals, it may lead to serious complications.
Other microorganisms can also contaminate improperly stored meat products.
How long should deli meats stay in the refrigerator?
General food-storage guidance for refrigerated deli meats includes:
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Opened packages or freshly sliced deli meats: approximately three to five days.
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Unopened packages of certain prepackaged luncheon meats: approximately two weeks, provided they remain within the manufacturer's use-by date and storage instructions.
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Cooked sausages and leftovers: generally three to four days.
The exact period depends on the product, packaging, processing method, and manufacturer's instructions.
Always follow the label, particularly for products that require refrigeration before opening.
If the meat becomes slimy, develops an unpleasant odor, shows mold, or has unusual discoloration, discard it.
Do not assume that heating spoiled processed meat will make it safe.
The connection between processed meat and colorectal cancer
Food safety is not the only reason to pay attention to processed meats.
The World Health Organization's International Agency for Research on Cancer has classified processed meat as carcinogenic to humans, based on evidence linking its consumption with colorectal cancer.
Processed meat includes meat that has been transformed through salting, curing, fermentation, smoking, or other processes designed to improve flavor or preservation.
Examples include:
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Bacon.
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Ham.
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Sausages.
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Hot dogs.
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Salami.
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Some smoked and cured meat products.
This classification does not mean that eating one sausage causes cancer.
It means that evidence supports a causal relationship between processed meat consumption and colorectal cancer, particularly with regular consumption over time.
The IARC has estimated that eating 50 grams of processed meat every day is associated with approximately an 18% higher relative risk of colorectal cancer.
This is a relative increase, not an 18-percentage-point increase in an individual's absolute risk.
The practical message is to limit processed meat consumption rather than panic about an occasional serving.
Choose a varied diet that includes vegetables, fruits, whole grains, legumes, fish, and other protein sources.
4. Spoiled Seafood: A Food Safety Risk You Should Never Ignore
Seafood is nutritious and can provide high-quality protein, omega-3 fatty acids, vitamin B12, iodine, and other important nutrients.
But fish, shrimp, squid, and shellfish are highly perishable foods.
They require careful handling from the moment they are harvested until they reach the kitchen.
When seafood is stored improperly, bacteria can multiply rapidly. Certain species of fish can also develop toxins that are not destroyed by ordinary cooking.
Why seafood spoils quickly
Seafood generally has a high moisture content and delicate tissues.
After harvesting, natural enzymes and microorganisms begin breaking down the flesh. If seafood is not chilled promptly, this process accelerates.
Common warning signs include:
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A strong, unpleasant, or ammonia-like odor.
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Slimy surfaces.
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Mushy or unusually soft flesh.
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Discoloration.
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Damaged packaging.
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Unusual liquid collecting in the container.
Fresh fish should generally have a mild smell rather than a strong, sour, or ammonia-like odor.
Fresh shrimp should be firm and should not have an unpleasant smell.
Shellfish should come from reliable sources and be handled according to appropriate food-safety guidance.
However, appearance and smell alone cannot guarantee safety. Some dangerous toxins and pathogens may be present without obvious signs of spoilage.
The special danger of histamine in certain fish
Some fish, particularly tuna, mackerel, mahi-mahi, and other species with naturally high histidine levels, can develop histamine when they are not properly chilled.
Certain bacteria convert histidine into histamine.
This can cause scombroid fish poisoning.
Symptoms may include:
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Facial flushing.
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Headache.
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A rash or hives.
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A burning or peppery sensation in the mouth.
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Nausea.
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Vomiting.
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Diarrhea.
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A rapid heartbeat.
One important detail is that cooking, freezing, or reheating does not reliably destroy histamine once it has formed.
This is why proper temperature control is essential from the moment fish is caught.
Shellfish can contain toxins that cooking cannot eliminate
Certain shellfish, including mussels, clams, and oysters, can accumulate marine biotoxins produced by harmful algae.
These toxins may cause different forms of shellfish poisoning.
Depending on the toxin, symptoms can include vomiting, diarrhea, tingling, numbness, muscle weakness, or neurological problems.
Some marine toxins are heat-stable. This means ordinary cooking cannot be relied upon to make contaminated shellfish safe.
Buying seafood from approved and traceable suppliers is particularly important.
Never collect shellfish from waters that have been closed to harvesting because of harmful algal blooms or contamination.