How safe is the American food supply? Very safe, if you ask the experts—probably the safest in the world. But, even so, if food isn't handled correctly and becomes contaminated by disease-causing bacteria (pathogens), it can still make you sick.

Most of the disease-causing bacteria reside on the outside of food. This is especially true of meat, poultry, and fish. If meat is cut up or ground, the bacteria now has an additional surface on which to grow.

For the most part, bacteria are rendered harmless when meat, fish, or poultry is fully cooked to medium or well-done temperatures. The bacteria on a whole piece of meat are found only on a limited number of surfaces, unlike the multiple surfaces of ground meats.

In the grinding process, the meat becomes inverted—the middle becomes the outside and the outside becomes the middle. Grilling the hamburger kills the surface pathogens that are present, but doesn't necessarily kill those lurking on the inside unless the meat is fully cooked. Consider using a food thermometer to make sure meat is fully cooked. The color and texture aren't always enough to go by. Make sure you know how to use the thermometer properly and that you know what temperature your food should be at to be safe.

At a barbecue, hamburgers are often brought out to the grill on a platter. If the platter is used again to bring the cooked food to the table, without being washed in between, the cooked hamburgers served on that platter may become contaminated.

The cheese on a cheeseburger can become contaminated if it's brought to the grill on the same platter as the raw hamburger. Although the cheese cooks on top of the hamburger, it isn't fully cooked.

Some foodborne illnesses have been traced to the lettuce and cheese on a burger. In one case, the lettuce and cheese were stored under the hamburger, which was on the top shelf, and the meat dripped on the lettuce and the cheese. It's important to store food properly. Make sure that all meat, poultry, and seafood is in containers or sealed plastic bags in the refrigerator. If you won't be using the foods within a few days, put them in the freezer instead. Keep eggs in their original containers and store them in the main part of the refrigerator, not the door.