Salmonella Prevention

The Issue

Salmonella are bacteria that cause intestinal illness (salmonellosis) in humans, usually because they have eaten contaminated food.

Background

Salmonella are a group of bacteria that normally live in the intestinal tracts of animals and birds. The bacteria are usually transmitted to people when they eat foods contaminated with animal feces. Contaminated foods are often of animal origin, such as beef, poultry, milk or eggs. But all foods, including fruits and vegetables, can become contaminated.

Approximately 6,000 to 12,000 cases of Salmonella are reported in Canada each year. Because many milder cases are not diagnosed or reported, or are believed to be the “stomach flu,” the actual number of infections is estimated to be many times more. Young children, seniors and those with weakened immune systems from diseases such as AIDS, or as a result of some cancer treatments, are the most vulnerable. The disease is more common in summer than in winter.

Sources of Salmonella

Contaminated foods, such as raw meat, poultry and eggs that have not been cooked properly, are the most common source of the disease. Not washing fresh fruits and vegetables before eating them, as well as not thoroughly cleaning work surfaces used to prepare raw meat and other foods in the kitchen can also expose you to Salmonella. Food can also be contaminated by food handlers who do not thoroughly wash their hands with soap after handling raw meat or after using the bathroom.

Salmonella can be found in the feces of some pets, especially those with diarrhea. Exotic pets, such as snakes, turtles and reptiles, may carry Salmonella even when healthy. People can become infected if they do not wash their hands after contact.

Health Effects of Salmonella

Most people infected with Salmonella develop diarrhea, fever and abdominal cramps 12 to 72 hours after being infected. The illness usually lasts four to seven days and most people recover without treatment. As with any disease causing diarrhea or vomiting, those infected should drink plenty of liquids to replace lost body fluids. This is particularly important with very young children and seniors. In severe cases, patients may need to be given fluids intravenously, which is usually done in hospital.

In a small number of cases, Salmonella may spread from the intestines to the blood stream and other body sites, causing severe illness and, in vulnerable people, death. In cases of severe illness, patients may be treated with antibiotics. However, some Salmonella bacteria have become resistant to many commonly used antibiotics.

A small number of infected people go on to develop pains in their joints, irritation of the eyes and painful urination, a condition called Reiter’s Syndrome. It can last for months or years, sometimes leading to chronic arthritis, which is difficult to treat.

Because many different illnesses cause the same symptoms as Salmonella, the only way to diagnose it is through laboratory tests on the stools of infected people. Once Salmonella has been identified, further testing can determine the type of Salmonella and the appropriate antibiotics to use in treatment.

Minimizing Your Risk

There is no vaccine to prevent salmonellosis, but you can minimize your chances of contracting it by following these steps.

• Contaminated foods may look and smell normal. Thoroughly cook foods to destroy the bacteria.
• Do not eat raw or undercooked eggs, poultry or meat. Remember raw eggs are contained in foods such as homemade hollandaise sauce, caesar and other salad dressings, tiramisu, homemade ice cream, homemade mayonnaise, cookie dough and frostings.
• Poultry and meat, including hamburgers, should be well-cooked, not pink in the middle. If you are served undercooked food in a restaurant, send it back.
• Avoid raw or unpasteurized milk and other dairy products. Mother’s milk is the safest food for infants. Breast feeding prevents salmonellosis and many other health problems.
• Thoroughly wash fruits and vegetables before eating them.
• When buying and storing groceries, keep meats separate from fruits, vegetables, cooked foods and ready-to-eat foods.
• Because bacteria grow quickly at room temperature, go directly home from grocery shopping and refrigerate or freeze food immediately.
• Always defrost food in the refrigerator, in cold water or in the microwave, never at room temperature. Set your refrigerator to 4 degrees C (40 degrees F) and your freezer to -18 degrees C (0 F).
• Wash your hands before handling any food. Be sure to wash your hands, cutting boards, counters, knives and other utensils after preparing uncooked foods.
• If you have been diagnosed with salmonellosis, do not prepare food or pour water for anyone else until you are clear of the bacteria.
• Wash your hands after contact with animal feces, for example, after changing the kitty litter or scooping up after your dog.
• Since reptiles can have Salmonella, always wash your hands after handling them. Reptiles, including turtles, are not appropriate pets for children and should not be in the same house as an infant.
• If you are diagnosed with salmonellosis, be sure that you or your doctor informs the local Public Health Department. If many cases occur at the same time, it may mean that a restaurant or a particular food item has a problem that needs to be corrected.

The Government of Canada’s Role

Health Canada sets policies and standards to ensure the safety and nutritional quality of all food sold in Canada. The Canadian Food Inspection Agency (CFIA) enforces the policies and standards and together with Health Canada helps to ensure that foodborne illness is detected early. The two organizations work together to ensure that all necessary warnings go out to the public quickly and that appropriate action is taken. When asked for help by a province, Health Canada will provide on-site expert assistance to help provincial health authorities identify the source of a Salmonella outbreak.

As a founding member of the Canadian Partnership for Consumer Food Safety Education, Health Canada also participates in public awareness campaigns about safe food practices. One example is Fight BAC™, a program that encourages Canadian consumers to think of food safety at every step of the food handling process, from shopping to preparing and re-heating foods.

Need More Info?

• For more Fight BAC™ tips
• For more information about Health Canada’s Food Program.
• For more about foodborne illnesses, visit Public Health Agency Web site.
• For more info on Canadian food issues/recalls, visit the Canadian Food Inspection Agency.

Safe Food Storage

Fresh? Frozen? Or shelf-stable? Food items in the supermarket are stored a certain way to maintain product quality and to keep foods safe. Once a food product has been chosen from the shelf or cooler, the consumer is responsible for making sure it is properly transported and stored at home. Failure to safely store food may cause bacteria in food to multiply and could result in a foodborne illness if the food is consumed.

At the supermarket

• Choose canned and dry goods first. Buy refrigerated/frozen and hot deli items last.
• Don’t choose cans that bulge, leak or are dented at the seam or rim.
• Double bag (in plastic) meat and poultry to prevent cross-contamination from any dripping juices.
• Check eggs to make sure that they are not cracked or dirty.

On your way home

• Foods containing bacteria that can cause foodborne illness can’t be in the “Danger Zone” (less than 60° C or 140° F or above 4° C or 40° F) longer than two hours. Bacteria multiply rapidly and can reach dangerous levels at this stage.
• Once you have purchased your food, go directly home. If this is not possible, place perishable foods in a cooler until you get home.

Storing shelf stable foods

• Store unopened dry foods, canned goods and high acid items (like ketchup, mustard and vinegar) in a clean, dry place where the temperature is neither too hot (above 100° F) or too cold. After opening, refrigerate any foods that need to be kept cool.
• Do not use food from cans or jars that are damaged.

Storing refrigerated food

Though food is refrigerated to prolong freshness and inhibit bacterial growth, there is a limit to how long food can be kept in the refrigerator. Once food begins to look or smell bad, it should be discarded. Follow these tips to help keep refrigerated food safe:

• Maintain a temperature of 4° C or 40° F or less to inhibit bacterial growth.
• Store eggs in their carton on a shelf, not in the door.
• Keep meat and poultry products in the original packaging. Less handling reduces the incidence of cross-contamination.
• Keep your refrigerator clean to avoid cross-contamination from spilled or spoiled foods.
• Don’t let meat or juices of raw meat and poultry contaminate other foods in the refrigerator.

Storing frozen foods

• Keeping food at -18°C (0° F) stops bacterial growth, but it will not kill bacteria already present.
• Food can safely be defrosted in the refrigerator, under cold running water or in the microwave. If you defrost food in the microwave, cook it immediately.
• Foods frozen near the beginning of their durable life will taste better than foods frozen near the end of their durable life.
• Food that is freezer burnt (dry in spots) is safe to eat (but may not taste very good).

Durable life information on food products

• Durable life is the amount of time that an unopened product will retain all of its wholesomeness, taste, nutritional value, and any other qualities claimed by the manufacturer, when stored under appropriate conditions.
• Manufacturers and retailers are responsible for determining the durable life of foods they manufacture and sell.
• Durable life information is not a guarantee of product safety.

For more information on foodborne illness and safe food handling practices, visit the Canadian Food Inspection Agency website at www.inspection.gc.ca

Microwave Ovens and Food Safety

http://www.hc-sc.gc.ca/hl-vs/iyh-vsv/prod/micro-f-a-eng.php

The Issue

Many Canadians use microwave ovens as a convenient way to thaw, cook and reheat food. A number of people have concerns, however, about the effect of microwaves on their health and on the health and safety of their foods.

Background

Many people who use microwave ovens say they are going to “nuke” their food. This reference to nuclear energy is incorrect and misleading. Microwaves are a form of radiofrequency electromagnetic energy. They are generated electronically. They do not come from radioactive sources and they do not cause food or the oven itself to become radioactive.

When microwaves penetrate food, they cause water molecules in the food to rotate. The rotation causes friction between the molecules and the result is a rapid rise in temperature. This is why the cooking time with microwave ovens is shorter than with conventional ovens. When you shut the microwave oven off, the microwaves disappear.

Health and Safety Concerns Associated With Microwave Cooking

Some microwave energy may leak from your oven while you are using it, but this would pose no known health risks, as long as the oven is properly maintained. The Need More Info? section below refers to an It’s Your Health article called Radiation Safety of Microwave Ovens. The article features safety tips to minimize your exposure to microwave energy when using a microwave oven.

Microwaves do not change the chemical components of in food and so the formation of new compounds, like carcinogens, is not expected. Some studies have been conducted to investigate any possible negative health effects of microwaving foods. These studies, which have been reviewed by Health Canada scientists, have found no evidence of toxicity or carcinogenicity.

In general, the health and safety concerns associated with microwave cooking are similar to the issues involved with other cooking methods, such as conventional ovens, stove-top cooking and grilling. For example, all cooking methods have some effect on the nutrients in food. The effect is worse if you over-cook the food. Microwave cooking tends to be less harsh on nutrients than conventional cooking methods, because the cooking times are shorter and less water is used. To help preserve nutrients when microwaving food, use techniques that promote the even distribution of heat. This will help prevent the formation of “hot spots” where portions of the food could be over-cooked. Steps to promote even heating are outlined in the Minimizing Your Risk section below.

There is no simple answer to questions about which cooking method is best for retaining nutrients. Research into the subject is ongoing. From a health perspective, there is no reason to use any one cooking method exclusively.

Other concerns associated with all methods of cooking, including microwave cooking, are foodborne illness and burns.

Minimizing Your Risk

Foodborne Illness

Raw food of animal origin, such as meats, seafood, poultry and eggs (including juices and drippings) may carry disease-causing bacteria. No matter which cooking method you use, the risk that bacteria will multiply and cause foodborne illness increases when foods are allowed to sit at temperatures in the “danger zone” between 4^o C and 60^o C (40^o F to 140^o F) for more than 2 hours. To minimize the risk of foodborne illness:

• When handling raw foods of animal origin, always chill promptly.
• Clean your hands and kitchen surfaces often.
• Keep foods separate and do not cross-contaminate.
• Cook food thoroughly.
• If you use the microwave oven to defrost or partially cook food, be sure to refrigerate or finish cooking the food by some other method right away. Do not let perishable foods linger in the “danger zone” for longer than 2 hours.
• Take steps to ensure that the microwave oven heats food evenly and does not leave underheated areas (cold spots) where bacteria might multiply and cause food poisoning. You can promote even heating in the microwave oven by:
  • cutting food into small pieces for uniform cooking
  • arranging items in a uniform manner
  • adding a liquid (such as water, juice or gravy) to solid foods
  • stopping part way through cooking to stir foods or rotate trays or containers
  • covering food with a microwave-safe lid or with microwave-safe plastic wrap to trap steam
  • following directions for “standing times”. This helps ensure that heat is distributed uniformly, even after cooking.
• Use a food thermometer to check that your food has reached a safe internal temperature. Take the temperature at several locations, especially in the thickest area of the meat, to ensure that the food is cooked all the way through. Make sure that the thermometer is inserted away from bone, fat or gristle. For example:
  • all ground beef products should be cooked to 71°C (160°F).
  • food mixtures containing poultry, eggs, meat and fish should be cooked to 74°C (165°F).
  • leftovers should be heated to 74°C (165°F).
  • Never cook whole poultry, including turkey in the microwave.

Burns

It is always important to be careful when handling or eating hot food. With conventional cooking methods, there are often warning signs that you are dealing with high temperatures. However, your microwave oven is enclosed and you cannot see the source of heat, so you may get a false sense of how hot the food and containers may be.

Therefore, with microwave ovens, there are specific concerns about potential burns related to:

• “superheated” liquids: These liquids are at or above the boiling point, but look harmless and show no sign (such as bubbling) that the liquid has boiled. When you remove superheated liquids from the microwave oven, they can erupt suddenly and cause serious skin burns.
• heat transfer from food to containers: Many microwave-safe containers and dishware are not heated directly by microwave energy. However, parts of these containers may become very hot due to heat transfer from the food being cooked.
• heating formula in baby bottles: When you heat baby formula in a microwave oven, the outer container (or baby bottle) may feel cool to the touch even though the formula inside is very hot. This can pose a risk of serious burns to the baby.

To minimize these risks when using the microwave oven:

• Be careful when heating liquids and removing them from the oven. Avoid superheating liquids by stopping the microwave oven part way through the heating process to stir the liquid.
• Always use containers labelled as microwave-safe.
• Use protective oven mitts or pot holders when you remove containers/dishware from the oven.
• If you heat a bottle of baby formula in the microwave, be sure to shake the contents and test the temperature of the formula on your own skin before you go ahead with feeding the baby. Health Canada recommends using conventional methods, such as a baby bottle warmer, to heat baby formula. With these methods, you can use the warmth of the bottle to measure the temperature of the inner liquid more accurately.

Other Concerns regarding Containers and Food Wraps

Some foods come wrapped in materials (e.g., styrofoam) that may not be suitable for use in the microwave. These materials could leach chemicals into your food or cause burns if they melt during microwave cooking. To minimize risks when using your microwave oven:

• Do not re-use trays or containers that come with convenience foods. These are designed for one-time use only.
• Do not use containers intended for cold storage (e.g., margarine tubs) or wrappings that come with packaged foods.
• Make sure the plastic wraps and containers you use are labelled as microwave-safe.

As a general safety precaution, always supervise young children when they use the microwave oven (or any other cooking appliance). Finally, read and follow the manufacturer’s directions for using the oven, and keep the oven in good working order.

Health Canada’s Role

Health Canada carries out many different activities to minimize risks related to the use of microwave ovens. For example, Health Canada has established a regulation under the Radiation Emitting Devices Act to govern the design, construction and functioning of microwave ovens that are imported, sold or leased in Canada. This regulation specifies limits for microwave leakage from ovens.

In addition, Health Canada assesses risks, sets standards and monitors the safety record of such products as microwave cooking containers and food packaging materials, and establishes policies on the safety and nutritional value of food. As a founding member of the Canadian Partnership for Consumer Food Safety Education, Health Canada also participates in public awareness campaigns about safe food practices. One example is CanFight BAC™, a program that encourages Canadian consumers to think of food safety at every step of the food handling process, from shopping for groceries to reheating leftovers.

Need More Info?

For information on Food Safety or contact: food-aliment@hc-sc.gc.ca

For more information on microwave radiation safety, contact:

The Consumer and Clinical Radiation Protection Bureau
775 Brookfield Road
Ottawa, ON K1A 1C1
Telephone: (613) 954-6699
Fax: (613) 952-7584
E-mail: CCRPB-PCRPCC@hc-sc.gc.ca

For additional information, visit the following Health Canada Web sites:

• It’s Your Health – Radiation Safety of Microwave Ovens
• For information on food packaging.

Additional information can also be located at:

• The Canadian Food Inspection Agency Web site, Food Safety Facts on Microwave Ovens.
• CanFight BAC™

For additional articles on other issues go to the It’s Your Health Web site.
You can also call (613) 957-2991.

Original: July 2005
© Her Majesty the Queen in Right of Canada,
represented by the Minister of Health, 2005L