A bit of dirt might just do us all good

How clean is too clean? How dirty can we be and still be healthy?

No matter which hygiene question you prefer to ask, this is one matter best mediated by one hand washing the other. Let Dr Gary Noskin explain:

"Always stop to wash your hands when they are visibly soiled," says Noskin, medical director of infection control at North-western Memorial Hospital, who has done numerous studies of the subject.

"We should wash them any time we come in contact with bacteria or viruses, such as when we touch our noses or use the bathroom. Our findings show that using soap, water and friction for 25 to 30 seconds is most effective."

Passing bacteria and viruses among us is the most common way we get sick with an infectious disease, including colds and flu. Hand-to-hand contact is a big culprit, as is touching items such as tap handles or telephones that harbour bacteria and other germs. That's why hand washing is a must for daily health.

Yet an ongoing scientific debate focuses on whether there is such a thing as being too clean. Researchers have been asking - and finding - that perhaps our homes and indoor environments are overly resistant to germs. There is growing scepticism about whether antibacterial soaps are necessary.

The American Medical Association has asked the Government to expedite review of such products to determine if they pose a health threat by encouraging the growth of super-resistant bacteria. It has even been argued that a young child covered head to toe in grime might be strengthening his immune system rather than just tracking in mud.

Dr Stuart Levy, of Tufts University School of Medicine in Boston, is an outspoken critic of antibacterial soaps and cleansers. He said these products were providing a false sense of security among consumers and "could be promoting superbugs that might otherwise be kept in check."

"The vast majority of bacteria are out there serving a purpose for us," he said. "They help our intestinal tract, and our immune system, to mature." Antibacterial soaps had no proven benefit over mild soap and water.

He recommends using stronger hand cleansers only when someone in the house is seriously ill or has lowered immunity. Parents might think they are doing the right thing using antibacterial soaps and household cleaners, strong laundry detergents, antiseptic nappies and minimising exposure to other children and pets. Now, it seems, they may need to think again.