Dented cans — no deal or no problem?

It happens the same way every time.

I come home from a trip to the grocery store and begin putting the food away — a bag of grapes, a carton of mushrooms, half a gallon of milk — when suddenly, halfway to the pantry door, I look down at the can of tuna in my hand and notice a horrifying disfigurement: a dent.  My day instantly sours.

Dented cans have a long-established place in my list of personal neuroses.  My fear: the unlikely (but possible) risk of botulism contamination.  Botulism is a deadly illness caused by various strains of the Clostridium bacterium, most commonly Clostridium botulinum.  The bacteria has a strong affinity for low-oxygen environments (like cans and jars) and produces a neurotoxin that can cause victims to suffer increasing loss of muscle control. Gone untreated, the illness can spread from the face to the limbs, trunk and ultimately the respiratory system — resulting in death by suffocation. It’s a terrifying bacterium, every bit as nasty as its cousin Clostridium tetani, which causes tetanus.

My hesitation seems rational. Sure, most cans are processed with a pressure cooker that reaches temperatures high enough to kill off any adult bacteria and spores that might be present.  But improper canning happens — usually among people who can their own meats and veggies at home, although not always. In these instances, sneaky spores can inhabit the can, altering its shape and contaminating its contents. A can full of bacteria can appear swollen or misshapen. Additionally, the U.S. Department of Agriculture reports that deep dents — especially ones that create sharp edges or furrows in the metal — can damage the can’s seams allowing bacteria inside.

Yet even when I discover a dented can in my grocery bag, I often cringe at the thought of wasting what could be perfectly good food. So, before my latest hurt can of tuna got placed directly into the cabinet (where I’m pretty sure a dented can of refried beans I bought in January currently resides), I decided to figure out just how scared I should be about botulism contamination.

According to the Centers for Disease Control and Prevention, an average of just 145 cases of botulism are reported in the U.S. each year, equal to roughly 0.0000005 percent of the population. What’s more, just 15 percent of these are caused by foodborne bacteria. Even in the remote case of an infection, botulism doesn’t necessarily result in certain death — it can be treated at a hospital with antitoxins. These days, only about 3–5 percent of infected people die, although some will experience lingering effects like fatigue and shortness of breath for months or years afterward.

The misshapen cans in my cabinet are almost certainly the result of a bumpy trip home from the store, rather than multiplying bacteria — but it’s hard to shake that nagging paranoia. Yet armed with my new knowledge, I may break out the can opener tonight and finally dig into that dented can of refried beans. Bon appetít.