Re: House dust endotoxin study.

January 4, 2006

Had a look at the study abstract. No air concentration studies were

done. Symptoms were self reported. Here are my comments.

" Endotoxin concentration (EU/mg) and load (EU/m2) were highly

correlated (r = 0.73–0.79). "

The more dust the more endotoxins. No surprise here. Just a

housekeeping issue. My allergist always said to keep the house clean

and to remove all house dust regularly.

" Geometric mean endotoxin concentrations were as follows (in EU/mg):

bedroom floors, 35.3 (5th–95th percentile, 5.0–260); bedding, 18.7

(2.0–142); family room floors, 63.9 (11.5–331); sofas, 44.8 (6.4–240);

and kitchen floors, 80.5 (9.8–512). "

This shows at least two orders of magnitude in dust levels on the floor

and bedding. Some really poor housekeepers.

Multivariate analysis demonstrated significant relationships between

increasing endotoxin levels (Aka dust levels on the floor) and

diagnosed asthma, asthma symptoms in the past year, current use of

asthma medications, and wheezing among residents of the homes. These

relationships were strongest (?) for bedroom floor and bedding dust

and were observed in adults only. (An interesting inconsistency since

more children have asthma.)

" Modeling the joint effect of bedding and bedroom floor endotoxin on

recent asthma symptoms yielded an adjusted odds ratio of 2.83 (95%

confidence interval, 1.01–7.87). "

So when you compress you old dusty mattress and generate a dust cloud

and stir up the dust on the floor walking into the bedroom, you can

trigger asthma symptoms. So what exactly was the dose that triggered

the response? Can one be absolutely sure it was the endotoxins and not

the just the dust causing the asthma symptoms or a combination? This

is directly related to the recent discussion of irritation and allergic

reactions.

" When stratified by allergy status, allergic subjects with higher

endotoxin exposure were no more likely to have diagnosed asthma or

asthma symptoms than nonallergic subjects. "

No difference between allergic and non allergic subjects? Then, was it

just the dust and not endotoxins?

Bob

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