As Hurricane Sandy hits the Mid Atlantic, causing widespread damage in the form of flooding and downed trees, it also poses an invisible threat in the form of food spoilage. More than five million people have already lost power due to lines downed by the storm, and millions more are expected to be without electricity as Sandy continues its course. During a power outage, perishable food that is not kept at the proper temperature can spoil. Other foods risk contamination from flood waters seeping into containers. Government food safety officials recommend a series of measures to prevent food spoilage or avoid eating spoiled food. The U.S. Department of Agriculture and the federal Food and Drug Administration recommend taking the following precautions:

– Make ice cubes or freeze gel packs or containers of water so that you can keep food cold in the case of a power outage

– Group food together in the freezer to help it stay cooler longer

– Freeze refrigerated items you don’t need immediately, such as leftovers, fresh meat or milk

– Store food on high shelves or upper floors so that it will be out of the way of contaminated water should the house flood.

For those who have experienced a power outage, USDA and FDA recommend the following steps to keep food safe:

– If you have an appliance thermometer, use it to measure the internal temperature of the fridge and freezer. Refrigerators should stay at 40 degrees Fahrenheit, while freezers should be at zero degrees F.

– Put a block of ice or dry ice in the refrigerator or freezer to keep it cold. If you have access to dry ice, 50 pounds of it will keep an 18-cubic-foot refrigerator cold for 2 days, according to USDA.

– Keep the doors of the fridge and freezer closed as much as possible to keep them cold. An unopened refrigerator will keep food safely for about 4 hours without power if the door is unopened. A full freezer will hold its temperature for around 48 hours if unopened, according to USDA, while a half-full freezer will stay adequately cool for 24 hours.

In order to tell whether food is safe to eat after a power outage:

 – The first rule of post-emergency food safety is, “Never taste food to determine its safety!”, cautions USDA.

– If you have an appliance thermometer and determine that the interior temperature of the fridge dropped below 40 degrees F for more than 2 hours, discard any perishable items in it, including meat, poultry, fish, soft cheeses, eggs, leftovers and deli items. If food remained at the proper temperature, be sure to cook raw meats, poultry and eggs thoroughly to kill any foodborne pathogens that may be on it, advises FDA.

– If you do not have an appliance thermometer and your refrigerator remained without power for more than 4 hours or was opened repeatedly before that time, throw out perishable items. Foods that are still safe after being in the refrigerator for more than 2 hours above 40 degrees include hard and processed cheeses, butter or margarine, fruits and fruit juices, raw vegetables, fresh mushrooms, herbs and spices, opened vinegar-based dressings, peanut butter, and condiments such as jelly, relish, taco sauce, Worcestershire, Hoisin, soy and barbecue sauces, mustard, ketchup, olives and pickles. Condiments containing mayonnaise or fish sauce should be thrown out, as should fresh fruits that have been previously cut. For a full list of foods that can be kept or should be discarded, see  USDA’s Consumer’s Guide to Food Safety: Severe Storms and Hurricanes 

– When feeding infants, try to use prepared, canned baby formula that requires no added water. When using concentrated or powdered formulas, prepare with bottled water if the local water source is potentially contaminated, says FDA.

– Frozen foods will be safe and can be refrozen if the freezer remained at 40 degrees F or below during the power outage. If you don’t have a thermometer, but the food still contains ice crystals, it can be refrozen.

– Wash fruits and vegetables with water from a safe source before eating.

 After Flooding

– Drink bottled water that has not been exposed to floodwaters if it’s available. If not, heat tap water to a boil before drinking. If the water is cloudy, filter it through clean cloths or allow it to settle, drawing off the clear water for boiling.

– If you can’t boil water, disinfect it with household bleach, advises FDA. Add 1/8 teaspoon, of regular, unscented liquid household bleach to each gallon of water, and let it stand for 30 minutes before drinking.

– Discard any food that may have come into contact with floodwater if it is not in a sealed, waterproof container. Lids that are not waterproof include screw of snap-tops, pull tops and crimped caps.

– Discard any damaged cans of food. For undamaged, watertight containers of food, remove labels since they may be harboring bacteria, and thoroughly wash packaging with soap and water, using hot water if it’s available. Sanitize cans and sealed pouches by either boiling them in hot water for two minutes or placing them in bleached water (1 tablespoon of liquid bleach per gallon) for 15 minutes.

– Use the same sanitizing process for dishes and pans exposed to floodwaters.

– Thoroughly wash countertops with soap and water, then apply bleached water (1 tablespoon per gallon) to these surfaces.

A video on food safety during a power outage is available on USDA’s Food Safety and Inspection Service‘s website.