A 'bag monster' at a U.S. grocery store gives shoppers the message that there are too many plastic bags in use. (Kim Komenich/Associated Press)

Canadians should wash their cloth grocery bags frequently, especially after carrying fresh produce or meat, Health Canada said Wednesday.

Reusable bags and bins help reduce the use of plastic, but it is important to prevent cross-contamination with bacteria that cause food-borne illnesses, the department said.

"Because these bags and plastic bins are reused frequently, they can pick up bacteria from the foods they carry, or from their environment (the ground, the back of your car or the items stored in them between grocery trips)," Health Canada said in a release.

Health Canada's tips to prevent cross-contamination include:

• When using cloth bags, make sure to wash them frequently, especially after carrying fresh produce, meat, poultry or fish.
• Reusable grocery bags may not all be machine washable. If they aren't, wash them frequently by hand, with hot soapy water. Plastic bins should also be washed regularly using hot soapy water.
• Put fresh or frozen raw meat, poultry and fish in separate bins or bags, away from fresh produce and other ready-to-eat foods.
• Putting fresh or frozen raw meat, poultry or fish in plastic bags will help prevent the juices from leaking out and contaminating your reusable containers and other foods. (The clear bags found in the produce and some meat sections work well for this.)
• Fresh produce should also always be put in plastic bags to protect it from contamination.
• If you are using your grocery bags or bins to store or transport non-food items, wash them thoroughly before using them for groceries.

Last month, the Canadian Plastics Industry Association commissioned a study of reusable bags that suggested nearly 30 per cent (seven of 25 bags tested) had bacterial counts higher than the amount considered safe for drinking water, and 64 per cent of used reusable bags (16 of 25) had some level of bacterial contamination.

About 11 million cases of food-related illnesses occur in Canada every year, according to Health Canada.