Dust May Protect Kids from Asthma
A common bacterial toxin found in not-so-clean environments, from farm animal pens to household dust, may help protect young children from developing allergies and asthma, new studies suggest.
Researchers say the results suggest a reason for the lower risk of allergies and allergy-triggered asthma that has been found among children who grow up on farms or with household pets. Bacterial components called endotoxins, which are particularly high when farm animals are around, may push the developing immune system to tolerate the environmental irritants commonly behind allergies.
The new study, conducted in rural Germany, Austria, and Switzerland, found that school-age children whose mattresses contained relatively higher levels of endotoxins were less likely to suffer from hay fever or allergy-related asthma, or to show sensitization to airborne allergens like pollen and cat dander. The findings are in the September 19th issue of the 2002 New England Journal of Medicine.
Endotoxins exists in the cell wall of certain bacteria, and the feces of larger animals are a major source of endotoxins exposure, although household pets, as well as dust and dirt, offer up their share. Early childhood exposures to farm animals, pets and dust, as well as to other children in places like day care, have all been tied to a lower risk of developing allergies and asthma. Researchers explain this connection with the so-called "Hygiene Hypothesis", which holds that exposure to bacteria, viruses and their byproducts early in life helps push the developing immune system toward infection-fighting mode, and away from the tendency to overreact to environmental irritants. Some investigators point to increasingly clean living in industrialized societies as one reason for their growing rates of asthma.