IAQA - White Paper Archives

IAQA 18th Annual Meeting & Indoor Environment and Energy Expo (IE3) The views and opinions herein are those of the volunteer authors and may not reflect the views and opinions of IAQA. The information is offered in good faith and believed to be reliable but it is provided without warranty, expressed or implied, as to the merchantability, fitness for a particular purpose or any other matter. Looking at the relationship between spore counts in the air and endotoxin levels in the dust (Figure below), we did not find a correlation between them (R2=0.0398). Some areas with low spore counts had high endotoxin and some areas with high spores had low endotoxin. There was no discernible pattern. Discussion We found that moldiness levels in homes were not positively correlated to endotoxin in the dust and thus they were not good predictors of one another.This was also the conclusion of similar research published comparing endotoxin in the air with moldiness. Other published studies have looked at levels of fungi, dust mites and Gram negative bacteria postulating that they would co-exist due to the common need of available water sources. However, they also found that endotoxin was unrelated to reported mold. One other publication found endotoxin and spore trap data poorly or not related at all to beta-glucan or ergosterol which are strong measures of moldiness and fungal load. ERMI (qPCR for mold) was also found not related to endotoxin levels. Overall, this dataindicates then that it really depends on the nature of the water event or damage whether or not Gram negative bacteria are going to be present with ensuing higher levels of endotoxin. In residential buildings this would mean black water events that introducea high load of bacterial contaminants. Water dripping through the roof, for example, would not give that same introduction of Gram negative bacteria. Researchers have found that endotoxin levels are positively correlated with the presence of a dog or even the past presence of a dog in the home. Also, positively correlated with the use of a cool-mist humidifier but negatively correlated with the use of a dehumidifier or central air conditioner. Presumably lowering humidity levels will help control condensation on surfaces and available water for bacteria to grow. High levels of endotoxin were found to be predicted by lower family income, presence of a child, dog, cat, cockroaches, smokers in the home, carpeted floors, and overall poor hygiene practices in the home. People exposed to endotoxin were significantly associated with wheeze in the past 12 months, wheeze during exercise and the use of prescription medications for wheeze.With allergies continuing to rise over the years in our population, we should not discount the presence and effect of endotoxin in our indoor environments. Bibliography Endogenous endotoxin-core antibody (EndoCAb) as a marker of endotoxin exposure and a prognostic indicator: a review. 1995.Barclay, GR., ProgClinBiol Res. 392:263-72. Bacterial Endotoxins: Lipopolysaccharides from Genes to Therapy. 1995. Editors Jack Levin, Carl R Alving, Robert S Munford and Heinz Red, John Wiley & Sons Inc., New York Relationship Between Dust Endotoxin Levels and Mould Spore Counts y = -26.646x + 6641.3 R 2 = 0.0398 -5000 0 5000 10000 15000 20000 25000 0 50 100 150 200 250 300 Endotoxin Levels in Household Dust (EU/mg) Maximum Total Spores (counts/m3)

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