That hairline crack in an egg carton may look harmless. But food safety experts say it can turn a simple breakfast into a potential salmonella risk, as Food & Wine reports.

What's happening?

Once the shell is damaged, the egg loses part of its natural defense against contamination, the outlet noted. If the crack happened before you bought it, experts told Food & Wine that the safest move is simple if blunt. Leave that egg at the store.

Food & Wine spoke with experts who said shoppers should never buy eggs with cracked shells, even if the damage seems minor. A broken shell can give bacteria a point of entry, increasing the risk that the egg is no longer safe to eat.

Dr. Vanessa Coffman, Alliance Director for Stop Foodborne Illness, told Food & Wine that the estimate is about one salmonella-positive egg for every 20,000 shell eggs in the United States. A crack can increase the chance of bacterial growth, especially when the egg's protective barrier has already been compromised.

"The biggest concern is that you don't know how long the egg has been cracked or what it may have been exposed to during storage, transport, or handling," certified culinary scientist Jessica Gavin told Food & Wine.

There is no reliable way to tell how long it has been exposed or what it may have touched. That means even a tiny flaw in the shell should be taken seriously at the grocery store, where shoppers have no reliable way to know when the damage happened.

Why does it matter? 

Eggs are an everyday staple, used for quick breakfasts, baking, and inexpensive meals. So it's highly possible these pitfalls are ever-present in many consumers' diets.

The risks are also higher for certain groups. Coffman warned Food & Wine that older adults, children, pregnant women, and people with weakened immune systems are more likely to get sick and face more severe complications from salmonellosis.

There is also the problem of contamination beyond the cracked egg itself. Food & Wine reported that if any liquid leaks out, bacteria can be transferred to hands, countertops, the carton, and nearby eggs.

What can I do?

The first thing is not to take a cracked egg home. If you do happen to crack an egg on the way home or in your kitchen, experts say it may still be usable, but timing matters. Coffman recommended refrigerating it right away or ideally cooking it without delay, Food & Wine reported.

Gavin advised against storing an accidentally cracked egg for later use. Cracked eggs can also be used in foods that will be fully cooked, such as baked goods or other recipes in which the egg will not remain runny, per Food & Wine. Undercooked yolks are not the safest option in this situation.

Food & Wine reported that if the egg leaks onto the carton, the other eggs should be cooked thoroughly, hands should be washed, and any surfaces the raw egg touched should be cleaned. If it is not clear when or how the crack happened, Food & Wine advised throwing it out, and for good reason.

"Even a tiny crack weakens the egg's natural protective barrier, making it easier for bacteria like salmonella to enter through the porous shell," Gavin explained to Food & Wine.

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