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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 (e.g., on the processing line from plant equipment or employees). They can be accidental or be deliberately introduced to the food (i.e. tampering).

In general, there are three health concerns usually associated with physical hazards (often referred to as extraneous material):

  1. Physical injury to the lips, inside the mouth, teeth, tongue, throat, oesophagus, stomach, colon
  2. Choking
  3. Product Tampering

Many types of extraneous material may be present in foods. Extraneous material that is associated with food may include bone fragments, hair or feathers from animal products. Stones, rocks and dirt are commonly found in foods that are grown close to the soil like fruits and vegetables. Metal is a common physical hazard that can be introduced anywhere along the food chain from field to consumer, but is most commonly associated with processing activities such as cutting, slicing, or grinding operations. Extraneous material can be introduced by anything that comes in contact with the food (e.g., from the person that handles the food or during transportation or storage). Jewelry and personal items are common physical contaminants that may be present due to poor food handling. [1] Extraneous material which originates from packaging or containers (e.g., glass would be included in this area of concern).

Examples of types of extraneous material include:

  • plastic
  • glass pieces, fragments, particles
  • wood
  • industrial rubber
  • metal pieces or shavings, wire, fragments, particles, injection needles, snap off knife blades, meat hooks or mesh gloves
  • fragments of equipment (e.g., belt lacing, sheared off bolts, nuts, nails, washers, pump parts, rubber, tool parts)
  • stones
  • shell fragments
  • pit fragments
  • cleaning equipment: sponges, cloth, bristles, tissue fragments
  • packaging material
  • metal twist ties, elastic bands, string
  • "quik" locks (the plastic closure tags used to close bakery products)
  • infestations, insect parts, rodent droppings, organic filth
  • medications
  • band-aid, finger cots (rubber or latex sock used to cover a finger), glove or glove fragments
  • tartrate crystals (wine diamonds)
  • struvite (mineral deposits in canned fish products)
  • anything else foreign to the food product such as pens, pencils, eyeglasses, keys, paper clips, staples, jewelry
  • live infestations
  • bone fragments

This section of the Reference Database for Hazard Identification contains information on extraneous material including guidelines that relate to the safety and cleanliness of food, factors in determining risk and the control of physical hazards.

Other Information

Extraneous Material Guidelines

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 is generally less tolerated than Unavoidable because it is preventable. It 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 jewellery, 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. These guidelines are designed to limit extraneous material in specific foods. The CFIA uses the guidelines to interpret relevant sections of the Food and Drugs Act (FDA) and to make decisions on the necessary follow up actions. Extraneous material may be evaluated on a case by case basis depending on whether appropriate guidelines are available.

Harmful or injurious extraneous material is often assessed in priority. Health Canada evaluates injurious extraneous material in food and it considers 2.0 mm or greater as the threshold size for consideration as a health risk. [2] Besides size, the risk associated with extraneous material is further evaluated through an assessment of shape, hardness, material, source, target consumer groups, quantity, etc.

Choking Hazards

Potential choking hazards are evaluated individually on a case-by-case basis, based on different characteristics including size, shape, ingredients, consistency, method of consumption, previous fatalities, medical opinion, etc. Of special concern is product in which a potential choking hazard seems to be associated with the product design.

Industry should take steps to eliminate or minimize the presence of extraneous matter in food. Prior to release, industry is encouraged to evaluate the product design carefully with a view to ensuring that the design properties themselves do not contribute to a potential choking hazard.

Factors in Determining Risk

Food companies including retailers, manufacturers, distributors, and importers, should be aware of the risk associated with the food products they distribute. Even though Health Canada considers extraneous material 2 mm in size or greater as the threshold for consideration as a health risk, a number of factors are evaluated when risk is assessed. Factors in determining the potential risk of physical injury to consumers include but are not limited to:

  • target audience for the food
  • type of product
  • method of consumption
  • size of the extraneous material
  • hardness of the extraneous material
  • sharpness of the extraneous material
  • shape of the extraneous material
  • type of extraneous material
  • ease of discovery

Extraneous materials found in high risk products including infant foods and beverages (due to the method of consumption) are considered most hazardous, and should be addressed immediately. Table 1 summarizes the injury risk of extraneous materials that are based on Health Canada's Field Compliance Guide 90-2. [2]

Table 1: Injury Risk of Extraneous Materials

Injury Risk - Commodity - Size of Extraneous Material

High - Infant Foods - Any size (including small particles less than 2 mm)

Violation: Section 4(a) of the Food and Drugs Act (FDA), which states "no person shall sell an article of food that has in or on it any poisonous or harmful substances"

High - Beverages - 2 mm or larger in size in any one dimension

Violation: Section 4(a) of the Food and Drugs Act (FDA), which states "no person shall sell an article of food that has in or on it any poisonous or harmful substances"

Moderate - All other foods (except infant foods or beverages) - 2 mm or larger in size in any one dimension

Violation: Section 4(a) of the Food and Drugs Act (FDA) which states "no person shall sell an article of food that has in or on it any poisonous or harmful substances"

Low - All other foods (except infant foods) - Less than 2 mm in size in all dimensions

Control of Physical Hazards

The key to controlling physical hazards in food is prevention. Extraneous material control is an important part of any product control system and is a built-in component of successful programs such as HACCP and GMP. Extraneous material can also serve as an indicator of other non-visual problems within an establishment (i.e. evidence of rodent activity indicates poor sanitation or pest control). In other words, sound extraneous material control usually reflects positively on other aspects of plant operations.

Control of physical contamination begins with the identification of raw material ingredients or packaging components that are at risk. An effective control program must include a commitment from vendors and suppliers. Proper maintenance of the buildings, facilities, grounds and processing equipment will help to further reduce the risk of introducing extraneous material into the finished product. [3]

Once hazards have been identified, a control program can be designed to manage and reduce these risks. Tools of the overall program include the implementation of an effective HACCP System, which consists of a prerequisite program and a HACCP plan. Information regarding HACCP may be found in the CFIA website at Food Safety Enhancement Program

Another means of controlling physical hazards is to be able to find them and remove them if, and when, they occur. Some common strategies employed for the control of physical hazards include [3], [4], [5]:

  • Physical exclusion of the hazard (e.g., screens, filters and sieves, etc.)
  • Effective detection and elimination systems
  • Proper equipment design, selection, calibration and maintenance
  • Effective facility maintenance
  • On-line visual inspection
  • Detection methods include metal detectors, x-ray machines, optical systems, magnets
  • Employee training program
  • Good Manufacturing Practices
  • Eliminate potential sources of extraneous material within the establishment
  • Screening assessment of raw materials
  • End product screening
  • Consumer feedback or complaint analysis

Examples: [1], [4]

  • A filter or sieve can be used to remove physical objects. The sieve plate allows small particles to pass and removes larger objects.
  • A water bath can be used to remove debris such as rocks, stones, and dirt from fruits and vegetables. Heavy objects like stones and rocks fall to the bottom of the bath where they can be removed.
  • When metal is a concern, a metal detector can be used. A calibrated metal detector can identify a food that contains a metal object so that food can be examined more closely.
  • Glass problems can be minimized through strict container controls and an efficient glass breakage policy on and around the processing line. Other controls include visual examination of empty glass containers, or cleaning a container with water or compressed air and inverting the container to remove any shards.
  • Light fixtures should be protected.
  • Good food handler training is needed since the food handler is an important source of physical hazards. Food handlers should be aware of the physical hazards that could be on their clothing or hands (such as jewelry and personal items such as artificial fingernails) and other items that could end up in food. Some companies, under their GMPs, do not allow metallic pens or other loose items in the production area.
  • An effective sanitation program includes good procedures for cleaning and sanitizing equipment. Effective sanitation also helps to reduce the possibility of physical hazards in the food.
  • Properly and regularly maintain equipment in the food facility to avoid sources of physical hazards such as foreign materials that can come from worn out equipment
  • Inspect raw materials and food ingredients for field contaminants (e.g., Stones in cereals) that were not found during the initial receiving process
  • Effective pest control can prevent pests from entering the production area and contaminating products during storage.

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

While important in itself, extraneous material control often provides a useful visual indicator of the overall sanitation level of the establishment. Obvious problems involving physical contamination usually reflect potential microbiological concerns and an overall lack of attention to the kind of detail needed for the consistent production and handling of safe and wholesome food.


  • [1] Cooperative Extension Services, Purdue University and Virginia Tech. Module 1: Understanding Hazards Associated with Foods. 1999.
  • [2] Health Canada. Field Compliance Guide 90-2, Subject: Injurious Extraneous Material. Ottawa: Health Products and Food Branch, Health Canada, 1990.
  • [3] Keener, Larry. "Chemical and Physical Hazards: The "Other" Food Safety Risks": Food Testing & Analysis. U.S.A.: The Target Group, 2001.
  • [4] U.S. Food and Drug Administration. Good Manufacturing Practices (GMPs) for the 21st Century - Food Processing Section Two: Literature Review of Common Food Safety Problems and Applicable Controls. 2004.
  • [5] Baughman, Kim. "Identifying and Combating Hazards in Food Processing" U.S.A.: Microbac Laboratories Inc., 2005.

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