How clean is too clean?

I witnessed an interesting scene at the supermarket last week. A mother with a toddler in tow cleaned a shopping trolley handle with (what looked like) antibacterial wipes from her handbag before allowing her daughter to sit in the child seat. Was she being a good mother concerned with hygiene or a complete germophobe?   The fact is the scene made me beg the question – is there such a phenomenon as being ‘too clean’? And are we as a society actually doing ourselves harm by fanatically striving for a ‘germ-free’ environment?

It was as recently as the mid-19th century that the practice of hand washing and sanitisation was first thought to reduce the mortality associated with infections. Dr Ignaz Semmelweis, a Hungarian obstetrician proposed this theory in 1847 after noting that the mortality rate associated with  childbirth fever dropped from 10-35% to less than 1% if doctors were made to wash their hands in chlorinated lime solution before examining patients. Unfortunately, this suggestion was considered extremely radical by the scientific community of the time and Semmelweis’ work was laughingly rejected. It took Louis Pasteur and his ‘germ theory of disease’ almost twenty years later for Semmelweis’ hypothesis to gain widespread acceptance. Nowadays, it seems ludicrous to think otherwise as antiseptic procedures have become so indoctrinated into everyday life.

The question I ask though, is have we taken this principle too far? For example, I am amazed at the range of ‘antiseptic’ products that have hit the markets in the space of a few years. In 2006 when I was planning to backpack around India, I struggled to find antiseptic hand wash in my local supermarket. These days it seems that a bottle of hand sanitiser is carried in most handbags with the same importance as an iphone or lip-gloss.

Interestingly, there is a growing mound of evidence to suggest that by decreasing the incidence of infections in Western and more recently developing countries, we have inadvertently increased the rates of autoimmune and allergic diseases. In the scientific community this is known as the ‘hygiene theory’ – the theory being that micro-organisms and parasites help to regulate and influence the development of the human immune system. They teach the immune system what is foreign and needs to be eliminated versus what is self and should be ignored. By ridding our environment of these microbes over the last century, our immune systems are no longer exposed to these challenges and have become confused rogue agents who overreact to normal stimuli.


The theory is based on decades of statistical data which shows a marked rise in the incidence of allergic and autoimmune diseases for the children of migrants within several generations of moving to developed ‘cleaner’ countries. More recently this data has been validated by animal and human trials. For the most part, the theory explains the phenomenal rise in the rates of diseases such as asthma, hay-fever, eczema, type 1 diabetes and multiple sclerosis for the Western world.

Of course it is not hand washing alone that has eliminated microbes from our environment. The past two centuries has seen the advent of sewerage systems and clean water, the introduction of immunization programs and broad spectrum antibiotics as well as the treatment and control of food to prevent bacterial contamination. I am not suggesting that we stop using any of the above – clearly they have drastically improved the health and quality of life of the general populace. At the same time however, it is sobering to think that we as a society may have inadvertently created medicine’s next major crisis.

The consensus from the scientific and medical communities is one of common sense – when it comes to protection against micro-organisms, moderation is the key. It should also be noted that some micro-organisms are in fact a part of the ‘normal’ makeup of the human body’s defence system and at any given time, can be found to live harmoniously in and on their human hosts. The reality of the situation is that most environmental bugs and simple infections (including those lurking on the handle of a humble shopping trolley), whilst annoying at the time, are not life-threatening.

So the next time you catch the seasonal cold or virus, think of it as a learning experience for your immune system.

Rowena Lalji is a doctor based in Brisbane who fuels both her career in medicine and her passion for writing using the nectar of the gods – expresso coffee.

Are you a clean freak? Have you bought hand sanitiser for your handbag? Do you believe the “dirt is good” philosophy or do you keep your bottle of Spray and Wipe close by at all times?

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