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Physical Hazards

Illness and injury can result from hard foreign objects in food. These physical hazards can be introduced anywhere along the food chain from the field source up to and including the consumer. They can be inherent in the product, of field origin or derived raw materials or packaging. They can originate from many different sources (for example, on the processing line from plant equipment or employees).

Many types of extraneous material may be present in foods. Examples of physical hazards include:

  • bone or shell fragments, hair or feathers from animal products
  • stones, rocks and dirt (commonly found in fruits, vegetables and other foods that are grown close to the soil)
  • metal (commonly associated with processing activities such as cutting, slicing or grinding operations, as well packaging materials or containers such as metal shards, staples and nails)
  • jewelry and personal items (resulting from poor food handling practices)
  • glass or other contaminants from packaging materials or containers, or from the processing environment, for example, uncovered light fixtures
  • wood splinters from broken pallets or packaging material
  • flaking paint from overhead structures or equipment
  • insect pieces

Other Information

Unavoidable and avoidable extraneous material

Unavoidable and avoidable extraneous materials are two categories used to differentiate extraneous material in food.

Unavoidable extraneous material may occur in food as a by-product of the processing system or as something inherent to the product itself. Items such as stems in blueberries, microscopic airborne debris, dirt on potatoes, or minute insect fragments in figs are common examples of unavoidable extraneous matter.

Avoidable extraneous material consists of foreign matter which should not be present if proper GMPs are followed. Avoidable extraneous material may come in many different forms such as small glass fragments, pieces of plastic, chunks of rubber, pieces of jewelery, feather barbules, animal debris or any other unrelated foreign material.

Health Canada has developed a guidance document for determining the general cleanliness of foods. The document, Guidelines for the General Cleanliness of Food - An Overview includes information on foreign matter associated with objectionable conditions or practices in manufacturing, processing, storing, transporting and handling of food. Health Canada considers 2.0 mm or greater as the threshold size for consideration as a health risk.[1] For infant food, any size of injurious extraneous material may be considered a risk. Besides size, the risk associated with extraneous material is further evaluated through an assessment of shape, hardness, material, source, target consumer groups, etc.

For information on methods for the analysis of extraneous material in foods, including glass, magnetic metal particles and heavy filth, refer to Health Canada's Volume 4 - The Compendium of Analytical Methods.


  • [1] Health Canada. Field Compliance Guide 90-2, Subject: Injurious Extraneous Material. Ottawa: Health Products and Food Branch, Health Canada, 1990.

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