A Bit Of Dirt Will Not Kill You by Nick Vassilev

When I was in my student days, one of my flatmates was a microbiology undergraduate. Over one fortnight, she had an experiment which involved Petri dishes being placed at odd places around the house and left to grow mould. Now, we all know student fridges can be bit dubious at the best of times, but while Katy (name changed for privacy reasons) had her bacterium cultures growing in the fridge, you just didn't want to look very hard...

Katy also kept us informed about the amount of bacteria that float around the typical house and the millions of bacteria that grow in tea towels. But were we constantly sick in that flat? No. Did we scour the place regularly with hospital grade antiseptic and boil everything in sight? No. OK, we did change the teatowels daily.

The truth is that the human immune system does a pretty good job of keeping you safe from most of the invaders that try to make their way into the system. And another uncomfortable truth is that using too many disinfectants and antiseptics around the house can actually be dangerous for you.

One doctor (Dr Paul Brand, the medical missionary to India who made some crucial breakthroughs in understanding and treating leprosy) claims that a commercial antiseptic is "merely a cell-killer [which] also destroys the body's good cells... the average American household is more in danger from chemical germ-killers than from germs" (Fearfully and Wonderfully Made (1981) pg.19). No doctor would dismiss the need for antiseptics completely (during surgery, for instance) or turn the body's defences totally over to the white blood cells and go about drinking dubious water, eating unsafe food and so forth, but Dr Brand certainly has a point.

Have you ever noticed what happens to your skin if you get strong disinfectant on it? My skin, at any rate, becomes dry and cracked. This is because the antiseptic chemicals are not just killing the bacteria in my toilet, but they are also killing my skin cells. And let's not forget the toxic fumes that other antiseptics produce, especially chlorine bleach.

It's tempting to want to kill all the germs that could possibly live in our environment, especially if we have small children who we want to protect from illness. But we need to stop and think before we try to give all the toys a weekly dunk in disinfectant or bring out the hospital-grade disinfectants for all food-preparation surfaces. If you've been feeding your child decent food, he/she will probably have a pretty sound immune system. I've even read one scientist hypothesising that the reason for the increase in allergies is because children's healthy immune systems don't get much to work on in a sterilised environment, so they start reacting to innocuous stuff (Strachan, DP. Hay fever, hygiene, and household size. BMJ 299: 1259'1260, 1989). A little bit of dirt doesn't hurt.

In fact, a bit of dirt can actually be good for you. No, don't eat it deliberately. But getting hands in the dirt and rolling in the grass was one prescription given by a specialist to somebody who had contracted a "superbug" while they were in hospital (probably Staphylococcus aureus, the best known antibiotic-resistant bacterium). This is because S. aureus is something of a wimp in the bacteria world and usually gets dealt to by all the other bacteria, etc. in our environment - its one strength is the ability to survive antibiotics and the like. When the other bacteria are removed, S. areus has a field day.

There may be another reason why getting a bit dirty can help deal to "superbugs". Dirt contains a vast amount of bacteria and micorrhizae (moulds and fungi), some of which have not yet been classified by scientists. Some of these bacteria and mould are likely to be beneficial - there could very easily be a hitherto undiscovered antibiotic in the mud on the bottom of your Wellington boots. After all, Alexander Fleming discovered penicillin on a piece of mouldy bread which most of us would have thrown out in horror, if we found it in our cupboard.

So what do we do? How do we keep healthy without going over the top? - Eat well - give your immune system all the strength it can get.

- Be sensible and minimise the amount of germs that your system has to deal with - wash your hands before eating, cook food properly and don't go out of your way to eat dirt.

- Keep your house clean, but don't try to make it sterile.

- Don't worry about hidden dirt - just get rid of the visible stuff.

- Let your kids play outside and get dirty occasionally. Get dirty yourself once in a while.

- Have your vaccinations - this is boot camp for your white blood cells so they can deal to the really nasty illnesses.

- Don't bother with antibacterial soap - ordinary soap will do just fine.

- Don't ask your doctor for antibiotics for every little illness - save these for when you really need them.