Contamination is an ongoing problem in our food supply. From threats of biological and chemical contamination to the presence of foreign materials in our food, contamination is leading to more and more food recalls. 


Between 2013 and 2018, food recalls due to contamination increased 10%, and Class I recalls of meat and poultry — which are recalls prompted by the belief that there is a “reasonable probability” that the food is contaminated — rose an unprecedented 83%.


To prevent food contamination, it’s important to understand how food becomes contaminated, where those contaminants come from and what methods can be used to eliminate the risk of distributing contaminated food.

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How Food
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Table of Contents

What is food contamination?


Food contamination typically refers to foods that have been spoiled or tainted, either by coming in contact with toxic substances, being infiltrated by foreign materials, or because they contain microorganisms such as bacteria or parasites. 

All three of these types of contamination (chemical, physical and biological) can enter the supply chain through a number of different ways and make food unsafe for eating

The problems created by food contamination can be long lasting, both to consumers and to the brands that provide the food. According to the World Health Organization, the most common problems created by biological contamination are vomiting and diarrhea, while contamination from toxins such as heavy metals can cause long-term health problems such as cancer and neurological disorders. 

Additionally, contamination of food by foreign material can pose a threat for choking, dental damage, laceration of the throat, mouth and intestines or, in extreme cases, even death. 

The type of contamination that occurs will determine what steps must be taken to resolve the problem. And, in every instance of contamination, it’s important to determine where the contamination occurred to be able to eliminate the threat and prevent it from happening again.


How food gets contaminated throughout the production chain


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1. Production 

Food safety has been a concern for consumers since the early days of our industrialized food production system. As more processed foods have entered our world, so have greater risks for contamination.

From wires for cutting meat and cheese to metal flakes and fragments from cutting blades to nuts, bolts and rubber gaskets from machinery, there are many ways contaminants enter our food supply.

In the past few decades, X-ray detection for food has become a viable form of threat detection for manufacturers. As technology improves and the costs drop, food manufacturers have more choice in how to approach their food safety options. The introduction of X-ray inspection as an offline service provides the ideal complement to inline inspection capabilities.

Since third-party offline systems run at a slower rate, they can find even smaller foreign materials — down to 0.2 mm and less in some cases. At FlexXray, we use a custom-built system that leverages medical-grade technology that inline flat panel detectors can’t compete with. As technology continues to advance, so will innovations in food inspection — and so will the level of food safety enjoyed by consumers and manufacturers alike.


2. Processing

Processing is necessary to turn plants and animals into food, and each type of food has a different process it must go through. Depending on the type of processing required, contamination can come from such things as pathogens in storage containers that spread to the food inside them or when germs from an animal’s hide or intestines come in contact with the meat during the slaughter process. Or, if the water used to wash or pack fruits and vegetables is contaminated, it will contaminate those items as well.

The processing stage is also where foreign materials can enter food; the equipment used in processing may break and end up in the food, or workers may drop something into the food production line. Foreign materials entering the food at this stage can include bone, glass, metal, wood, cloth, screens and rust.

Food manufacturers can also run into problems within their plants that affect food safety, which is why such things as a robust pest control program and cleanliness of a facility should always be a priority. 

Creating a comprehensive food safety plan is one way to avoid some of the common contamination issues at this stage. And using proper food inspection processes to ensure that no foreign materials have entered the food, either during the production process or the actual processing, can improve the safety of food products as well.


3. Distribution 

Getting the food to the consumer — whether that means a restaurant, grocery store or something else — has its own set of challenges when it comes to food safety. In most cases, several steps are involved, with each step adding the potential for some sort of contamination to occur.

One common form of contamination in this part of the process comes from food not being kept at safe temperatures. This can happen if the truck that’s transporting it is not at the proper temperature or if the food is left on the loading dock for too long. 

Food can also become contaminated if the truck was not properly cleaned between deliveries; for example, if a truck was transporting animals, and then is transporting a load of vegetables, the vegetables could become contaminated if the truck was not cleaned in between the deliveries.

At this stage, the risks for physical contamination are lower, since the food is sealed and manufacturers have systems in place for preventing foreign materials from entering their food.


4. Preparation 

When it comes to food preparation, mishandling food can play a big role in contamination. If it is undercooked or left out on the counter, it can be susceptible to food-borne illness. 

But physical contamination can occur from items that get into the food, either accidentally (jewelry from a worker falls into the food or preparation utensils break in the food) or intentionally through employee sabotage.

Types of Food Contamination


Food can become contaminated in many different ways, and depending on the type of contamination, it will fall into one of four areas: biological contamination, chemical contamination, physical contamination and cross-contamination.

While recalls due to biological contaminants seem to be in the headlines almost daily, the fact is that physical contaminants are more common than biological ones. 

A five-year study by Stericycle found that foreign materials are the leading cause of food recalls. Let’s take a closer look at each type of contamination:



1. Biological

Biological contamination is the cause of many recalls, and the Center for Science in the Public Interest attributes most biological outbreaks to produce. Produce also causes the greatest number of illnesses per outbreak, with some of the more common occurrences attributed to E. coli and salmonella.

Other forms of biological contamination come from bacteria, viruses or parasites and are transferred through saliva, pest droppings, blood and fecal matter. Biological contamination is believed to be the most common cause of food poisoning worldwide.



2. Chemical

Food is exposed to chemicals at different points throughout the growth and production process. Some of the most common sources of chemical contamination are agrochemicals, including pesticides and veterinary drugs; environmental sources such as polluted water, air or soil; the migration of chemicals from packaging materials and the use of unapproved food additives.


3. Physical

Physical contamination occurs when a foreign object accidentally makes its way into food products — or when natural objects, such as bone, are left in the food. According to the FDA, physical contaminants come in two categories: hard/sharp physical hazards and choking hazards. Both of these are extremely dangerous because they can cause physical injuries that can, in extreme cases, lead to death.


4. Cross-contamination 

Cross-contamination is the process in which bacteria or other microorganisms are accidentally transferred from one surface or object to another and the results are harmful. (Some examples would be the transfer from cutting boards and utensils that are not cleaned properly between uses.)

“While recalls due to biological contaminants seem to be in the headlines almost daily, the fact is that physical contaminants are more common than biological ones. ”

Common sources of physical contamination of food


Physical contaminants can occur at any point in the food supply chain. The type of contaminant typically can help identify where it came from. 

Here’s a look at some of the more common examples of physical contaminants and where they come from:


Metal. Metal can end up in food products during the farming process and through different stages of food processing. If a metal blade snaps during the cutting or harvesting of plants, fragments of metal from that blade could be unknowingly passed along in the food. During processing, a machine may lose a nut or a bolt that falls into the food, or a broken piece of equipment may produce metal fragments and shavings that land in the food.

Bone. Bone is most likely to be found in meat products, and it’s a risk to any food producer working with meat. As a solution, many producers will use deboned meat as the raw ingredient, or they may use a specialized bone removal system.


Glass. Whenever the production process includes the use of glass containers, there’s a risk that some glass will end up in the product. Mechanized handling of the glass can increase the chances of breakage, but glass contamination can happen through any type of packaging method. In some cases, glass fragments can even get into the food as the result of overhead lights breaking in a production facility.

Plastic. When facilities use hard plastic tools and equipment (such as paddles and buckets), the plastic will wear down over time. This leads to cracks and breakage which, if not detected, can result in the plastic ending up in the food product. In 2018, plastic topped the list of foreign contaminants found in food.

Rubber. Between 2015 and 2016, contamination of food by rubber products increased 22%. That’s largely because rubber is such a commonly used material in manufacturing to create seals and O-rings that prevent leakage into the food. When those rubber parts wear out, they can break into fragments and fall into the food.

Wood. Wood contamination in food is fairly common as well; it comes from either wooden utensils and equipment used in manufacturing or from wood pallets used to transport the food.


Stone. Stones and rocks are most often a natural contaminant that enters the food early in the process. They aren’t toxic, like many other types of physical contaminants, but can cause choking or internal injury if swallowed. 

Risks of food contamination


Food contamination carries many risks, both physical and financial. It poses a threat to consumers and manufacturers alike and can cause lasting harm to both.

For consumers, the greatest threats of food contamination come from the health and safety risks they’re exposed to. Biological and chemical contamination of food can cause health problems including food poisoning and illness from harmful bacteria, viruses and parasites, or the exposure to chemical compounds that cause illness or injury. 

Physical contaminants can lead to problems ranging from choking hazards and damaged dental work to injuries such as lacerations that can, in extreme circumstances, lead to death.

Food companies face a different set of threats when it comes to food contamination. A single incident can have a lasting effect on a brand’s image and lead to costly lawsuits and recalls. 

If contaminated food causes injury or death, it can quickly lead to expensive lawsuits. And, according to Food Safety Magazine, the average recall costs a food manufacturing company at least $10 million. Those costs include notifying any pertinent regulatory bodies, the supply chain and consumers

It also includes the price of retrieving and destroying product that has already been shipped and destroying any related product still at the plant. There’s the cost of labor to perform those tasks, plus the labor costs to produce a replacement run of the product.

Even more harmful than the direct cost can be the expensive, long-lasting consumer response to a recall. After the threat has been removed, it can still influence consumer buying habits. 

One study found that, in the year following recalls of spinach and peanut butter, about 75% of consumers quit buying those products, even if they came from a different brand or manufacturer. And, according to a poll by Harris Interactive, 16% of consumers said they wouldn’t purchase that type of product from a company following a recall — and 17% would avoid all products made by that manufacturer.

Taking the right precautions can eliminate the risks both to consumers and manufacturers.

“16% of consumers said they wouldn’t purchase that type of product from a company following a recall — and 17% would avoid all products made by that manufacturer. ”

Download our X-ray food inspection case study, “What Should I Do If I Have a Foreign Material Problem?”

Let us show you how X-ray food inspection can help resolve your foreign material problems.


How to detect and remove physical contaminants


Metal Detector


X-Ray Inspection

Fortunately, ever-improving technology allows us to avoid physical contamination of food more efficiently and cost-effectively than ever before.

There are three primary types of food inspection machines or systems that can help detect foreign objects in food while it is still in the production stage. They are:

Magnetic separators. The simplest method, which can gather objects that contain iron and some types of stainless steel

Food Metal detectors. These are designed to locate metal contaminants in food as it passes through the manufacturing line

Food X-ray machines. Locate and reject potential foreign contaminants based on differences in product density

While all of these forms of detection have contributed to greater food safety, none of them can provide the kind of accurate inspection provided by FlexXray’s X-ray inspection. 

For example, metal detectors for food are effective at identifying metal particles, but won’t help if the product is contaminated with another type of foreign particle, such as bone or plastic. They also aren’t able to be used to inspect products in aluminum-coated packing materials.

Of all the methods of foreign object detection, X-ray food inspection is proven to be the most accurate and sophisticated, providing an effective way to prevent contaminated food from reaching customers. However, there are significant differences between inline X-ray inspection machines and third-party X-ray services such as those provided by FlexXray.  

The FlexXray difference


One of the biggest factors affecting the inline inspection process is line speed. While inline machines can locate fragments and contaminants within food products, they also must keep up with the speed of manufacturing. That prevents them from being able to consistently detect objects below 3mm or 5mm.

There’s also a notable difference between the size of inline X-ray machines and FlexXray’s custom machines. While inline inspections use flat panel detectors (similar to what is used for baggage screenings at airports), FlexXray uses medical-grade technology that allows the person monitoring the line to zoom in and enlarge the area for closer inspection.

An inline machine is effective at detecting the presence of foreign particles in food but, due to the line speed, manufacturers likely will not know exactly what the contaminant is or precisely where it’s located. 

Rather than incurring the costs of reinspecting or reproducing the quarantined product, food manufacturers can turn to FlexXray to locate and eliminate the contaminant.

Because FlexXray is dedicated specifically to finding contaminants, we run product at a slower rate, allowing us to stop the line whenever a change in shading or density is noticed. 

After zooming in on the area, our line technician will identify if it is a foreign material and, if so, will remove the product from the line.

Once a physical contaminant is found and the product is removed from the line for safe and proper disposal, the rest of the production run is inspected to ensure there are no other contaminants. 

Then the safe, inspected food can re-enter the supply chain, where it is shipped to wholesalers or customers with the assurance that the food is safe and free of contaminants.

Talk to a Foreign Material Detection Expert

The safety of your product is only as good as the processes you have in place. Adding an extra layer of protection through X-ray food inspection gives you the ability to guarantee compliance and make better decisions for the future of your company.

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