If you have a health problem, especially one that may have impaired your immune system, don't eat raw shellfish and use only pasteurized milk and cheese, and pasteurized or concentrated ciders and juices.
Choose eggs that are refrigerated in the store. Before putting them in your cart, open the carton and make sure that the eggs are clean and none are cracked.
Select frozen foods and perishables such as meat, poultry or fish last. Always put these products in separate plastic bags so that drippings don't contaminate other foods in your shopping cart.
Don't buy frozen seafood if the packages are open, torn or crushed on the edges. Avoid packages that are above the frost line in the store's freezer. If the package cover is transparent, look for signs of frost or ice crystals. This could mean that the fish has either been stored for a long time or thawed and refrozen.
Check for cleanliness at the meat or fish counter and the salad bar. For instance, cooked shrimp lying on the same bed of ice as raw fish could become contaminated.
When shopping for shellfish, buy from markets that get their supplies from state-approved sources; stay clear of vendors who sell shellfish from roadside stands or the back of a truck. And if you're planning to harvest your own shellfish, heed posted warnings about the safety of the water.
Take an ice chest along to keep frozen and perishable foods cold if it will take more than an hour to get your groceries home.
Source: Excerpted from FDA Consumer - The Unwelcome Dinner Guest: Preventing Foodborne Illness, Jan.-Feb. 1991; Revised Dec. 1997, Feb. 1999, Oct. 1999, and June 2000