Toxins in Dust Raise Risk of Asthma

Dec. 1, 2005 - Bacterial toxins found in household dust may be a major risk factor for asthma, and the biggest problem may be in your bedroom.

A new nationwide study shows levels of bacterial toxins called endotoxins in house dust were directly related to asthma symptoms and use of asthma medications.

The strongest link between endotoxin levels and asthma risk was found in bedroom floors and bedding, even though concentrations of endotoxins in these areas were much lower than those in other areas of the house.

Researchers say it's the first national sampling of house dust, and the levels of endotoxins found in U.S. homes was much higher than those found in previous studies of European homes. This may be a factor in the increasing frequency of asthma in the U.S.

Endotoxins are toxic substances found in certain types of bacteria. These substances are released when the bacteria disintegrate. Previous research has shown that exposure to endotoxins can cause lung inflammation.

Common indoor sources of endotoxins include dust, pets, humidifiers, pests, and outdoor air.

Dust Component Linked to Asthma

In the study, reported in the American Journal of Respiratory and Critical Care Medicine, researchers evaluated dust samples from 831 U.S. homes. The residents of the homes also completed questionnaires about their health and asthma symptoms.

Researchers examined samples from five locations within the homes, including bedroom floors, bedding, family room floors, sofa surfaces, and kitchen floors.

The results showed endotoxin concentrations were highest in the kitchen and living room floor dust and lowest in bedding (mattress and pillow).

In addition, researchers found a significant relationship between household endotoxin levels and diagnosed asthma, recent asthma symptoms, and current use of asthma medications and wheezing.

The closest relationship between asthma risk and endotoxins was from endotoxin levels in the bedroom floor and bedding dust. But this relationship was found only in adults and not in children.

Researchers say the link between endotoxin levels and asthma was seen both in people with allergies and those without allergies. This suggests that the main impact of endotoxin exposure on asthma risk may be related to its effect on lung inflammation.