Types of cross contamination – What is cross contamination of food ?

Types of cross contamination – Cross contamination is the transfer of bacteria or microorganisms from one substance to another. Other types of cross contamination include transfer of food allergens, chemicals, or toxins. According to WHO, an estimated 600 million people fall ill and 420,000 people die each year after consuming contaminated food. Cross contamination is one of the factors that causes food poisoning. 

Anyone can experience cross contamination. However, there are several groups that are most vulnerable to experiencing it. Namely:

  1. Pregnant women
  2. Children under 5
  3. Adults over 65 years of age
  4. Those with weakened immune systems – for example, people with HIV / AIDS, uncontrolled diabetes, or cancer

Cross contamination of food may occur during food processing, transport, storage and distribution of food. We must really pay attention to what we consume. So, what are the types of cross-contamination of food?

Types of Cross Contamination

Type of cross-contamination in food there are 3 types, such us:

Food to Food

Raw food that are not cleaned properly would potentially be contaminated with bacteria. Some of the bacteria are Salmonella, Clostridium perfringens, Campylobacter, Staphylococcus aureus, E. coli, and Listeria monocytogenes. All of which could harm your health if you consume it. Some foods that have highest risk of contamination are seafood, green vegetables, bean sprouts, leftover rice, unpasteurized milk, soft cheeses, and raw eggs. Consuming uncooked fish and not cleaning it properly would cause food poisoning to consumers because it has been contaminated. Another example is that adding unwashed lettuce into a salad has the potential of contaminating the whole salad ingredients. Storing food in the refrigerator for too long could cause the bacterial overgrowth, which would cause cross-contamination to other foodstuffs in the refrigerator. 


The most common type of cross contamination but not many people are familiar with is the equipment-to-food contamination. According to Sarah Finn, the bacteria that causes cross-contamination can survive for a long time on the table, cutlery, cutting boards, storage containers and food manufacturing equipment. If we don’t clean up utensils properly, there is a potential for the transfer of large amounts of harmful bacteria to your food. This can happen at any time during food production / cooking, either at home or in a food factory. An example of this type of contamination that usually occurs at home is when we use the same cutting board and knife without washing it after cutting raw meat and vegetables. So, washing vegetables, hands, utensils or cutting board before & after food preparation is very important.

Human to food

Humans can easily cause the cross contamination in food. Bacteria can move from the body or clothing to food during the food preparation or processing process. For example, someone who coughs and covers their mouth with their palms and then without washing their hands touches the food has the potential to cross-contaminate the food. According to study data ­JSW Wong‘s 2019 on 190 adults, only 58% of participants reported washing their hands before cooking or preparing food. It indicates that cross-contamination from humans also has the potential to make food unsafe for consumption. The most effective way to reduce the risk of cross-contamination from humans is to wash your hands often & properly with soap and water for at least 20 seconds. 

This cross contamination will certainly have various effects on our bodies. Then, what are the side effects of consuming foods that have been cross-contaminated? 

Effects of Cross Contamination 

The side effects of eating cross contaminated food usually appear within 24 hours. These effects include stomach upset, loss of appetite, headache, nausea and diarrhea. Severe side effects include diarrhea for more than 3 days, bloody stools, fever, dehydration, organ failure, and even death. 

Given the type of cross contamination that occurs, it is very important to practice safe food handling when at home or in food processing companies so that there are no adverse effects to consumers. Food processing companies are required to carry out laboratory testing to test the bacteria content in food products before selling them to the market. 

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