Clean but Deadly: The Hidden Dangers of Cross-Contamination

You walked into your home (or office) that has just been deep cleaned. You observed that the grime that have been hidden in some corners have been completely cleaned off. Your home feels lighter – as though some heavy furniture has been removed! You did a quick check of your items and became reassured that nothing is missing. You smiled as it dawned on you that the lightness of your environment is as a result of accumulated dirt that has been cleaned away. You took a deep breathe…oh!..the freshness of your space is almost palpable! You concluded that your home has never been this clean!

But is it really clean? Is it free of disease-causing agents?


Research conducted by a team from the University of Buffalo revealed that bacteria such as S. pyogenes and S. pneumoniae can survive on surfaces for extended periods and can spread. In developing countries, S. pneumoniae which often leads to pneumonia and sepsis is responsible for the death of 1 million children each year!

If you or your loved ones regularly “mark attendance” at your family hospital, then you need to continue reading this article.

There are simple things you can do to keep healthy and keep the doctors away. One of such things is to avoid cross-contamination. By the end of this article, you will know what cross-contamination is, the various ways it occurs, its adverse effects on human health and practical ways to protect yourself and family from unhealthy exposures.

What is Cross-Contamination?

Cross-contamination is the process by which disease-causing micro-organisms or other contaminants are unintentionally transferred through unhygienic handling procedures from one object, site or person to another, with harmful effects on health. Cross-contamination is also known as cross-infection.

The three most common types of contaminants are:

  1. Biological contaminants such as bacteria, viruses and fungi
  2. Physical contaminants such as a piece of steel from your steel sponge
  3. Chemical contaminants such as insecticides

 How Does Cross-Contamination Occur

Cross Contamination mainly occurs during cleaning and food preparation.

During Cleaning:

Cross-contamination can occur when the same cleaning cloth is used to wipe the toilet bowl and the wash hand basin including the tap; or when the same cleaning cloth is used to wipe a kitchen top where raw meat has been prepared and to wipe every other surface in the kitchen. Cross-contamination can also occur when the same mop is used in the restrooms and other areas of the home or office.

During Food Preparation:

There are a number of places in which food can get contaminated: from
the factory where they are processed to the retails stores right down to the kitchen.
Cross-contamination can occur during meal preparation when the same knife and chopping board that was used in cutting raw meat is used, without thorough washing, to cut fruits or vegetables that would be eaten raw.
Other ways in which food can become contaminated include:

  • Leaving food uncovered
  • Sneezing or coughing near uncovered food
  • Touching parts of the body while handling food. For instance, scratching your nose will transfer bacteria to the fingernails which would in turn be transferred to food if hands are not washed
  • Not washing hands after going to the toilet during food handling
  • Licking fingers while handling food can transfer staphylococcus bacteria from the human saliva to food
  • Storing uncooked food (meat, fish) and ready to eat foods (fruits) in the same section of the refrigerator

Have you or your cleaning service provider been doing any of the above-mentioned things? If yes, you’ve been inadvertently spreading germs around your work/living space and exposing yourself and loved ones to avoidable health risks.

What are the Effects of Cross-Contamination?

Food Poisoning

You have probably suffered from food poisoning or know someone who has. The culprit for those intense stomach pains, nausea, diarrhea, and weakness that you felt is none other than contaminants that got into your system through cross-contamination.  When you eat food that is contaminated with E. Coli or Salmonella, the bacteria can multiply in your digestive tract and make you sick. Food poisoning arising from harmful strains of E Coli could lead to a type of kidney failure called Hemolytic Uremic Syndrome (HUS).  In severe cases, food poisoning has been known to lead to death. Pregnant women, babies, the elderly and people with weakened immune systems are more prone to the adverse effects of food poisoning.

 Food Intoxication

Food intoxication is a type of food poisoning caused by bacterial toxins. Although the bacteria Staphylococcus Aureus and Clostridium Botulinum will not make you sick, the toxins that they release into food can. Clostridium Botulinum bacteria can lead to a disease called botulism which if not properly treated can result in paralysis and possibly death within 3 to 7 days.

Mercury Poisoning

Mercury is a neurotoxin present in fish (tuna, swordfish and mackerel) that damages the nervous system, decreases fertility level and increases the risk of heart disease. Young children and pregnant women are the most vulnerable to the adverse effects of mercury poisoning.

 How Can Cross-Contamination be Prevented?

The measures for preventing cross-contamination are simple and well known; we only need to be reminded of them. We will look at the preventive measures under two sub-headings:

  1. Tips for preventing cross-contamination during cleaning
  2. Tips for preventing cross-contamination during food preparation

Tips for Preventing Cross-Contamination During Cleaning

Frequent and Proper Washing of your Hands.

I wash my hands several times during the course of any one day, so I am not really exposed to the dangers of cross contamination, right? Not necessarily right, particularly if you are not washing your hands the proper way. World Health Organization (WHO)  provided a pictorial guide to proper hand washing. See below:

Do not forget to wash your wrists also. It appears WHO missed that out! The whole hand washing process should take between 30 to 45 seconds. By thoroughly washing your hands, you minimize the risk of transferring germs across surfaces you touch and ultimately into your mouth. It is not enough to wash your hands properly, but you should wash them frequently. For instance, your hands should be washed before, during and after completing a cleaning task, before and after preparing or eating meals, before and after using the restrooms, before and after caring for a sick person and when you come in contact with animals or dirty surfaces.

Adopt Modern Cleaning Methods and Tools

Cleaning is as old as man. The Holy Book recorded that one of the major duties God gave to Adam was to tend the garden. Part of tending the garden would have involved keeping it clean and organized. Over the centuries, cleaning has been done using different methods and tools. Although it seems like another lifetime, I still have vivid recollections of me getting on my knees to labouriously clean the floors of an entire house using a rag!

The traditional string mop that has become so popular was patented in 1893. Owing to a number of limitations associated with the traditional string mop (excessive use of water and cleaning solutions, cross-contamination amongst others), the microfiber flat mop was developed. Microfiber mops are made of lint-free synthetic fibers which create a static charge that allows them to attract and retain dust and germs during cleaning, unlike traditional mops and cloths that spread dust and germs around. A case study conducted by the U.S. Environmental Protection Agency revealed that there was a 99% bacteria reduction on a surface cleaned using a microfiber mop as opposed to a 30% bacteria reduction on a surface cleaned using the traditional string mop. Switching from the traditional string mop to a microfiber mop will help minimize cross-contamination.

Other modern cleaning methods and tools that you could adopt to minimize cross-contamination include:

  1. Adopt the use of microfiber cloths, dusters and wands which are designed to capture 99% of bacteria and pathogens.
  2. Fold your microfiber cloth into four quadrants and use one quadrant per cleaning surface
  3. Where practicable, replace your regular vacuum cleaner with an HEPA (High Efficiency Particulate Air) filter vacuum that is capable of trapping even the smallest airborne particles and improving the indoor air quality of your living or workspace
  4. Clean from top to bottom and pay particular attention to such high-touch areas as door knobs, switches, railings and countertops

Use colour-coded cleaning tools (cloths, mops, mop buckets, dusters).

Assign specific colours to specific areas to be cleaned. For instance, red cloth for restrooms, blue for offices, classrooms and living room. Choose whatever colour works for you but take steps to document your colour code and ensure everyone who has to clean your space complies with the colour-coding system. This will ensure that the cleaning tools used do not unintentionally contaminate your space.

Separately Clean and Store Cleaning Tools

Mops, dusters and other cleaning tools should be properly cleaned and dried before they are stored as studies have shown that wet mops support the growth of bacteria. Your colour-coded cleaning tools should be cleaned separately and stored separately. For instance, when cleaning out your colour-coded mops, use separate buckets and water. Also, do not store bathroom mops next to kitchen mops or on top of each other. It is no use using colour coded cleaning materials if they will eventually be cleaned and stored together.

Personal Hygiene

Clean up and wear fresh clothes once your cleaning tasks have been concluded so that contaminants that may have settled on their clothes during cleaning will not be transferred to other surfaces

Tips for Preventing Cross-Contamination During Food Preparation

Some foods are more prone to food poisoning than others; therefore, special care needs to be taken in the handling, storage and preparation of such foods. These foods include chicken, meat, seafood, eggs, milk and all dairy products (yoghurt, cheese, butter and ice-cream).

Knowing the dangers of cross-contamination, do you want to make sure you prepare healthy meals that will nourish rather than poison your loved ones? The tips below will show you how.

  • Wash hands properly before, during and after preparing meals. Germs are invisible to the naked eye but under a microscope, we can see them for what they truly are!

Boy! These creatures look really horrible; little wonder they wreck such havoc on human health! Bearing a mental picture of how germs look should prompt you to take hand washing more seriously.

  • Use separate colour-coded cutting boards, knives and other utensils for the preparation of raw meat, fruits and vegetables. Alternatively, thoroughly wash utensils used for the preparation of raw meat before using same for fruits and vegetables
  • Thoroughly wash fruits and vegetables before eating; particularly when they are to be eaten raw
  • Store each type of food separately such that raw meat and their packaging do not come into contact with ready to eat foods
  • Put food away before using chemical sprays or cleaning agents
  • Cook foods to the right temperature that will kill bacteria. Most food poisoning germs cannot survive temperatures above 60°C
  • Store foods at temperatures that will inhibit growth. Most germs cannot multiply at temperatures below 5°C. Thawing and refreezing foods can promote the growth of bacteria. Therefore, foods should be stored in the refrigerator/freezer only in small portions that can be eaten once
  • Clean up spilled food in the refrigerator or cabinet as soon as they occur
  • Do not expose garbage in the cooking area or kitchen
  • Keep flies, cockroaches, rats and pets out of the kitchen
  • Areas where dry foods are stored should be regularly checked for evidence of the presence of pest eg rat droppings
  • Ensure all your cooking utensils are properly washed and dried before storing them away
  • Do not prepare meals for others when you are sick

The recent prevalence of hitherto uncommon diseases in Nigeria has debunked the general belief amongst Nigerians that “Disease no dey kill African man.” It is wisdom to save the money you would otherwise have spent on treating infections to have a fun-filled, relaxing time with your family in a well cleaned environment.

Your aim during cleaning should not only be to leave a place looking clean but also to ensure that it is contaminant-free. The practical measures mentioned in this article will help you to achieve this.

I recommend that you bookmark this page so that you can always make reference to it for practical tips you can adopt to avoid cross-contamination and keep healthy.

Please drop your comments in the comments section below; we will be happy to read them.


American Society for Microbiology 2013, Biofilm Formation Enhances Fomite Survival of Streptococcus pneumoniae and Streptococcus pyogenes, accessed 25th April 2019, Government (Department of Health) 2010, Food Poisoning and Contamination, accessed 3rd May 2019

Livestrong, Effects of Contaminated Food, accessed 28 May 2019,

LFA Tablet Presses, Different Types Of Contamination, Causes And Prevention For Pharmaceutical Industry, accessed 14th May 2019,

Canadian Food Inspection Agency 2017, Causes of Food Poisoning, accessed 8th May 2019,

About the Author

Banke Ogunlesi

Banke Ogunlesi started her career in 2007 as a Charted Stockbroker with a stockbroking firm in Lagos, Nigeria. After more than a decade in the financial industry, during which she rose to occupy middle and top management positions, she decided to pursue her dreams of creating clean, healthy and beautiful environments. She is currently the CEO of Blossom Crest Ltd.

27 thoughts on “Clean but Deadly: The Hidden Dangers of Cross-Contamination”

  1. Thank you for the priceless information; highlighting the importance of maintaining a healthy environment.

  2. This article is quite enlightening. Thank you for the detailed explanation of cross contamination. Truly good health is next to godliness. Incidentally cheap to maintain if one follows the tips you have outlined.

  3. This is fantastic Banks.
    It reminds me of your regular habit when you are studying in unilag as undergraduate and simultaneously preparing for your ican’ professional examination.
    Back then at cibn library, yaba, you are in the habit of putting a newspaper on the floor before placing your legs down and settled down to your studies.
    This was my observation of the degree of your neatness then!
    You are likely to be surprised because I never mention this to you for once!
    To me God has destined you to be great in taking cleaning as a business!
    This timely article demonstrated turning your passion into business!
    I am sold!

    • still remember the newspaper I’d always place on the floor! I’d actually forgotten. The final piece to a fulfilling study time was turning on my Walkman and plugging the earpiece to my ears. People would always ask me how I managed to study with the Walkman on. The combination for me was just perfect!

      Thank you for your kind words and for taking me down memory lane.

  4. This is very interesting, makes you know cleaning shouldn’t be done carelessly or absentmindedly, it is a conscious and deliberate act.

    I really never thought reading about cleaning will be such engaging, it shows your writing skills, you have made me a cleaner now.

    • Indeed, cleaning should be done with thorough planning and the utmost care because of its impact on health and productivity. Thank you for your kind words!

      • Thorough. Clean and clear detail about facts we often ignore or usually can’t see. The savings on cost of healthcare are invaluable! Thanks

        • True. We can consciously maintain a healthy lifestyle and save on healthcare cost by adopting some simple, practical tips. Thank you.

  5. This is a great write-up that is full of educative and insightful material. My eyes were opened on the contents
    Thank you. Well done

      • Wow very enlightening. The part that really got me is “Wash your hands before and after using the restroom” I knew it to be wash your hands after using the restroom. I have learnt so much from your article.

        Thanks I look forward to reading more of your article.

        • Yes, hands should be washed both before and after using the restroom. If hands are not washed before using the restroom, we stand the risk of transferring contaminants to our sensitive parts while using the restroom. Many thanks for your feedback.

        • Thorough. Clean and clear facts we often ignore or can’t see. Yet the enormous savings that knowing this means to healthcare is so obvious.

  6. Nice write-up Banke, I love it. I have learned a lot from this powerful article. Well done and please keep it up.

  7. This is an instructive article. I now understand cleaning better. I look forward to more of this kind. Welldone Banke.

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