Why You Should Never Buy Canned Food Without Checking The Cans For This

In an ideal world, we could trust every product we pick up off the shelves at grocery stores. But in the real world, we need to be vigilant and know the top signs telling us to avoid items at the supermarket in order to rest assured we're bringing safe, healthy food home. Some of these signifiers are helpfully obvious, like moldy bread, slimy greens, or grayish meat. But there's one sign that is less clear, and the consequences of missing it could be deadly: bulging cans. 

Bulging cans can be tricky because we can only see what's going on with the packaging, not its contents. But when it comes to bulging cans, it's dangerous to eat that food. The bulge tells us that something is going on inside. Bacterial activity and food spoiling can release gas that pushes against the can. In the worst case, bulging indicates that a can may not have been sealed properly, so bacteria like clostridium botulinum, which causes the potentially fatal botulism, can get in. The environment inside cans — low in oxygen and acidity, high in moisture — are this bacteria's best friends. This bacteria produces a toxin that can make it hard to breathe and that can even cause paralysis and death. Essentially, you can't be too careful here, and cans misshapen in any way are safest when avoided. If we drop a can at home that gets a ding or scratch, it shouldn't affect the food inside, but it's definitely best to avoid heavily dented or damaged cans in the store.

Botulism is rare these days, but not non-existent, hence the need to watch out for those bulging cans. It was once much more prevalent: We know about several devastating foodborne botulism outbreaks in U.S. history. Not all have been can-related, but a terrible bout in 2015 was indeed traced back to canned potatoes. And a notorious botulism outbreak that came from canned olives in 1919 is what triggered the first food recall in the U.S. in which 18 people died. This outbreak led to the beginnings of the modern American food safety system, as organizations were established to inspect food and its packaging. 

This kind of government-backed system is necessary but not foolproof. In the early 1970s, with the Food and Drug Administration decades underway, a man died and his wife became very ill from botulism-infected canned soup. The FDA could issue a public warning and recall, but couldn't catch the initial can, an understandably impossible feat with millions of products hitting shelves every day. Any number of things can happen between a can leaving a manufacturer and getting picked up by a shopper in a market. Botulism is undetectable — you can't see it, smell it, or taste it — but that bulging is quite visible. While it doesn't necessarily mean that particular bacteria is waiting inside the can, it at leasts communicates that something is wrong. The food inside is likely spoiled, and you'd be strongly advised not to eat it.