Latest News

This article features otherwise unpublished food safety management data held by BRCGS and the monitoring module in Safefood 360° which, combined with real-time events, provides an unparalleled view of current and emerging issues and trends in the food safety industry.

 

Physical contamination of foods with foreign bodies is a significant driver of product withdrawals and public recalls but it is also one of the biggest reasons for customer complaints relating to food. Given such importance it is surprising that it does not attract the level of attention of chemical and microbiological hazards. This article will focus on the common physical hazards and their control.

 

The Background

The Codex General Principles of Food Hygiene define a contaminant as “Any biological, chemical or physical agent, foreign matter or other substances not intentionally added to food that may compromise food safety or suitability”. In this context, physical agents and foreign matter, often collectively referred to as foreign bodies, can include a broad range of materials. This may include material that originates from the product itself including fruit stones/pips, stalks, shell, or material that originates from other external sources e.g. plastic from equipment, glass from containers, etc. In its broadest sense foreign bodies extend to the presence of dead insects and mouse droppings (faecal matter) even though such issues would also be considered as pest infestation. The key point is that the foreign body is a physical object that should not be present in the product.

Foreign bodies include a wide range of potential contaminants of food including plastic, glass, metal, wood, stones, bones, insects, soil, insects, faecal droppings (See Table 1). Their presence in food may pose a hazard to the consumer or may simply be visibly or organoleptically objectionable. In relation to safety, foreign bodies most present a risk of personal injury to the consumer through lacerations of the mouth or gastrointestinal tract from pieces of glass or hard plastic, shards of metal, splinters of wood, choking from large objects due to blockage of the oesophagus and damage to teeth from chewing on hard objects such as fruit stones, mineral stones, hard plastic and even congealed food ingredients. However, foreign objects can also introduce microbiological hazards, particularly enteric pathogens such as Salmonella spp. from soil, faecal matter and pests.

Table 1: Foreign bodies, the hazard and sources

Foreign body	Hazard	Source
Glass	Laceration Choking Tooth breakage	Jars Bottles Lights Windows
Metal	Laceration Choking Tooth breakage	Swarf Screws Nails Knives Blades Staples Jewellery Pens
Plastic	Laceration Choking Tooth damage	Conveyors Containers Paddles Gloves Packaging Brush bristles Pens Plasters
Stone	Choking Tooth damage	Food stones e.g. olives, peach, apricot, etc. Mineral stones e.g. pebble, grit, sand, etc.
Wood	Laceration Choking	Packaging Pallets Containers
Bones	Laceration Choking	Chicken bone Fish bone Meat bone
Hair	Microbiological Organoleptic	Head Arms Pubic
Paper	Choking Organoleptic	Packaging Labels
Shell	Tooth damage Organoleptic	Nuts Eggs
Pests	Microbiological Organoleptic	Insects Mice / rat droppings Feathers
Other	Various	Shot (game) Needles (meat) Teeth (produce)

 

Physical contamination of food causes a large number of product recalls globally. In a review of recalls during 2024 (BRCGS Recalls: A review of last year), physical contamination was the underlying cause of 4 - 28% of the total recalls in the four countries reviewed. Metal was the biggest cause of physical recalls in three of the four countries (Germany 52%, UK 45%, USA 36%) whereas plastic was the main driver in Australia (25%). No specific food group predominated in the recall data for physical contamination although there was a tendency towards processed foods including prepared and ambient food.

Food safety legislation throughout the world includes a requirement to manage the risk presented by physical hazards although they are generally not well defined. European Union Regulation 178 / 2002 on the general principles and requirements of food law defines a hazard as “a biological, chemical or physical agent in, or condition of food or feed with the potential to cause an adverse health effect”. It also states that food shall not be placed on the market if it is unsafe with the definition of “unsafe” including it being “unsafe for human consumption” as a consequence of contamination by “extraneous matter”. Similar definitions exist in the United States Food & Drug Administration (FDA) Food Code and foods contaminated with foreign materials would be considered adulterated by the US Department of Agriculture (USDA) Federal Meat Inspection Act and Poultry Products Inspection Act. Some legislative guidance provides reference to the control of specific physical hazards such as the FDA compliance policy guide on adulteration involving hard or sharp foreign objects.

Control of Foreign Bodies

A systematic approach to the identification of foreign body hazards is a critical first steps in establishing effective control strategies. The most effective tool for this is through the application of hazard analysis and critical control point (HACCP) as defined by Codex. Foreign bodies/physical hazards are a fundamental consideration in the HACCP exercise but, as with any hazard, if it is not clearly identified, measures for its control will not be present. Physical hazards may arise from raw materials, production equipment, the environment, people, packaging and, if the product is not pre-packaged, during subsequent transportation and storage stages. As mentioned already, it is essential for physical hazards to be clearly identified through mapping of the entire process from raw materials to the customer. This provides the opportunity to then develop specific interventions to reduce or eliminate the risk of foreign bodies in the finished product.

Physical hazards are very often controlled through prerequisite (preventive) measures with typical examples including raw material supplier assurance programmes, employee training, policies and procedures and equipment design, planned preventative maintenance to prevent equipment breakages such as blades or paddles, loose nuts and screws, pieces of material from fraying belts or plastic from conveyors and replacing or covering light fittings and windows, etc. Alternatively, specific controls may be introduced to remove the hazard completely or reduce it to an acceptable level such as filtering, sieving, magnetic separation or sorting raw materials and / or finished products. An excellent review of the controls for physical hazards has recently been published and other industry guides also serve as useful reference sources for foreign body control (IFST, DN Insert BRCGS Guide) and specific foreign body hazards.

Monitoring for Foreign Bodies

Approaches to monitoring for the presence of foreign bodies are essential parts of the overall assurance programme in relation to physical contamination management. A number of the systems employed to monitor foreign bodies in food may also play a dual role in delivering additional control of the foreign body at the same time. Good examples include metal detection and x-ray inspection that deliver 100% inspection of a production run. However, the limitations of using such systems for control purposes must be recognised as their sensitivity and applicability can very markedly between different foods and for particular foreign bodies.

Monitoring systems for foreign bodies can vary from the simple e.g. manual visual inspection by line operatives through to sophisticated and automated in line optical sensors (daylight, infra-red, near infra-red, microwave, etc). Records of monitoring activity should always be kept and these, together with associated monitoring schedules are usually part of a site quality management system. Some system based solutions exist that support effective monitoring (Safefood 360° Monitoring 2.0).

Systems for the control and monitoring of foreign bodies are summarised in Table 2.

 

Table 2: Benefits and limitations of foreign body control and monitoring systems

Technology	Benefits	Limitations
Visual inspection	Speed Cost Flexibility Simplicity	Subjective Fatigue Not 100% inspection Sensitivity Surface contaminants only
Optical sorting (light, infrared, laser, etc)	Speed Flexibility 100% inspection	Cost Surface contaminants only Sensitivity Free flowing materials only
Metal detection	Speed Cost Sensitivity 100% inspection	Conductive metals only Small fragments not detectable Not applicable for some foods Not applicable for some foods e.g. canned
X-Ray inspection	Speed Sensitivity 100% inspection Range of foreign bodies	Cost Low density materials e.g. papers, pests, etc.
Magnetic separation	Speed Cost Sensitivity	Ferrous materials only Free flowing foods / liquids only
Mechanical separation e.g. filtration, sieving.	Speed Cost Range of foreign bodies	Free flowing foods / liquids only Risk of contamination from equipment Sensitivity

 

Validation and verification

Any system employed for the control or detection of foreign bodies must be validated to ensure it can detect the foreign body in the specified food material at the required level of sensitivity. Where it is used for control, the validation must also include the rejection system. Validation involves trials to understand the operational capability of the system under foreseeable worst case conditions and verification is the ongoing testing of the system to ensure it operates within its defined parameters. Validation will help establish whether certain equipment is suitable for different food types such as the use of x-ray detection where the density of the expected foreign body may be so close to that of the food that reliable detection is not feasible. Similarly, it should test the line speed, orientation and any other significant variable likely to be experienced when in use. Once chosen, verification should be undertaken to ensure the system responds as specified when challenged with foods contaminated with the associated foreign body. Most people will be familiar with the verification of metal detectors using test pieces of defined sizes placed in different orientations and in the least sensitive part of the detector.

It goes without saying that verification procedures can in themselves present foreign body contamination risks and several recalls have been caused by the test product finding its way into the final product or where product in the rejected ‘bin’ is inadvertently replaced on the production line.

The importance of ensuring that individuals responsible for managing the foreign body control, detection, validation or verification stages are fully competent to carry out their duty. Such duties often required detailed understanding of the associated processes and must be undertaken by suitably skilled and or qualified individuals.

Third party certification schemes

Foreign body control and detection is a fundamental part of all GFSI-recognised food safety management programmes. The BRCGS Global Standard Food Safety has a number of requirements for management of physical hazards including specific clauses for metal control, glass, brittle plastic, ceramics and similar materials, products packed into glass or other brittle containers, wood and other physical contaminants. The Standard generally specifies requirements for a policy on the use, storage and monitoring of the specified foreign body together with procedures for situations where a foreign body/foreign body risk is encountered e.g. broken glass, It also has detailed requirements for foreign-body detection and associated removal equipment for filters and sieves, metal detectors and x-ray equipment, magnets, optical sorting equipment, container cleanliness and other foreign body detection and removal equipment.

Summary

Foreign body contamination is a significant and frequent risk in the manufacture, distribution and sale of a food product and I hope this article has given you a glimpse into the issues regarding the management of foreign bodies in the supply chain and the importance of controlling such hazards.

 

Author   Alec Kyriakides Independent Food Safety Consultant