Toxins in Dust Raise Risk of Asthma
Bacterial Toxins in Bedroom Floors and Bedding May Pose Major Asthma Risk
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
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
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.