The idea that we're too clean for our own good will be familiar to many. Scientists call it the hygiene hypothesis, and the theory is that far from benefiting our health, our obsession with cleanliness and hygiene is actually bad for us.
It's said that exposure to dirt and germs early in life 'primes' the immune system so it is prepared for any future threat - and that our constant wiping and sterilising of everything from kitchen work tops to children's toys may be undermining this important mechanism.
Last year, UK consumers spent £610 million on household cleaning products, up 16 per cent over a five-year period, according to market research experts Mintel. And the result of all this cleaning, according to proponents of the hygiene hypothesis, is an exponential growth in allergies.
The UK has one of the highest rates of allergy in the world - around 6,000 people a year need hospital treatment for potentially life-threatening reactions to animals, bee stings and foods such as peanuts.
Previously, researchers have focused mainly on allergies, asthma and eczema. Numerous studies show children raised on farms are less likely to get these diseases, either because they inhale all kinds of toxins or drink raw milk packed with bugs. Youngsters raised with cats or dogs also seem to be protected.
But now scientists believe the hygiene hypothesis could also explain the rising incidence of cancer.
Since the mid-Seventies, the number of people in the UK annually diagnosed with cancer has risen by 25 per cent, according to Cancer Research UK.
According to the hygiene hypothesis, repeated exposure to allergens, bacteria or certain toxins keeps the immune system on 'red alert', suppressing cancer cells in the earliest stages of development. Studies suggest that the more germs you get into your body, the less likely you are to get certain tumours.
Source - Daily Mail