October 21, 2005
Friday

It's not just your bed, it's an ecosystem, and a swampy one at that. New research has found that your pillow is home to millions of fungal spores from the bathroom, kitchen and other places where you might not want to rest your head.

It's well known that few people actually sleep alone: Most beds are home to thousands of microscopic dust mites, which produce so much excrement they can add a pound or two of weight to your mattress every year, by some estimates. Humans feed the mites by shedding dead skin, and add water from about 100 liters of sweat a year, says Ashley Woodcock, a researcher at the University of Manchester in England.

Still, he was surprised at both the amount and variety of fungi he found when he tested 10 pillows.

"We really thought it was the kind of stuff you find on a bathroom wall in a damp house. To find it in the bed you sleep in is really a surprise," said Woodcock, whose findings are to be published this week in the journal Allergy.

He and his colleagues found up to 16 species of fungi, including types normally found in bread and bathrooms, and a more worrisome species called Aspergillus fumigatus, which is the leading cause of death from infection in patients with leukemia and bone-marrow transplants.

Sleeping with fungi isn't dangerous for healthy people, Woodcock said. But it could be deadly for sick people, especially those with weakened immune systems. In the hospital, pillows are encased in plastic. But when patients return home, and are still vulnerable, they may be sleeping with fungi that can make them sick. Exposure to this fungus may also worsen asthma.

Woodcock's team examined 10 pillows that were between 18 months and 20 years old. The newer pillows did not have significantly fewer spores than the old ones, he said, so you can't make your bed fungi-free by buying a new pillow every few years.

Pillows made from synthetic materials were worse than feather pillows, Woodcock said. That may be significant for parents of children with asthma, or for adults who suffer from the illness. Many have been advised for years to use synthetic pillows to lessen their exposure to dust mites and the mites' feces, he added. Many experts believe exposure to dust mites - and their excrement - is an important factor in the increasing rate of asthma in children.

But in an earlier and much larger study, involving pillows in 150 homes, Woodcock found that synthetic pillows had five times more dust-mite fecal material than feather pillows, which usually are encased in tightly woven fabrics to keep in the feathers.

He noted that the kind of bedding people use has changed dramatically over the past 20 to 30 years. In many homes, blankets, which can be washed, have been replaced by comforters made from synthetic materials, which make people sweat more and can be harder to wash.

It is still just a theory, but he believes that the rise in childhood asthma rates may have something to with modern bedding. Parents might want to consider switching back to feather pillows, he said, or to quilts and blankets that can be washed regularly in hot water. Other experts recommend using plastic-covered mattresses, or encasing a regular mattress in a dust-mite-proof cover. They say blankets should be washed every month in hot water, and sheets should be washed every week.

Each bed, Woodcock said, is its own miniature ecosystem. Dust mites feed off fungi, which in turn may use dust-mite excrement as a source of nutrition. Then there is all that sweat, 100 liters a year a person, he added.

"Well, it is a feral soup, isn't it? It is an ideal culture medium for fungi."

At least fungi and dust mites don't bite. Bedbugs are making a comeback around the world, including in North America and Europe. Toronto and Vancouver are coping with infestations that have hit apartments, single-family homes, hotels and homeless shelters. Some pest-control companies report a 500 percent increase in calls about bedbugs over the past year. The bugs feed on human blood, and their bites can turn into itchy welts and become infected.

Getting rid of bedbugs is a lengthy and sometimes difficult process. They can hide in cracks in furniture, and even in tears in wallpaper, and in televisions, smoke detectors and curtains, and behind paintings. Pest-control companies recommend washing bedding and clothes in hot water and putting them in the dryer, and fumigating the areas where the insects are found.

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