Predictors of High Endotoxin Concentrations in the Settled Dust of German Homes

Abstract

Endotoxin concentrations in settled house dust were measured within the collaborative study named INGA (Indoor Exposure and Genetics in Asthma) together with other asthma-related indoor factors in 405 randomly selected homes in two German cities. Endotoxin was assayed using the quantitative kinetic chromogenic Limulus Amebocyte Lysate (LAL) method. The mean concentration of 2,274 ng endotoxin/g dust in living rooms is about two orders of magnitude below mean occupational exposure (e.g. agriculture). Endotoxin concentrations are higher in old buildings (means ratio = (MR) 1.52, 95% C.I.: 1.14; 2.04), and in the lower storey of the dwelling (MR = 1.30, 95% C.I.: 1.04; 1.62). Furthermore, higher endotoxin concentrations are associated with longer occupancy in the apartment (MR = 1.63, 95% C.I.: 1.21; 2.18), high utilisation of the apartment during the sampling period (MR = 2.52, 95% C.I.: 1.42; 4.47), infrequent vacuum cleaning of the carpets (MR = 1.67; 95% C.I.: 1.10; 2.54), an indifferent attitude to ventilation (MR = 1.37; 95% C.I.: 1.03; 1.82), keeping cats (MR = 1.91; 95% C.I.: 1.43; 2.55) and dogs (1.57; 95% C.I.: 1.08; 2.30), as well as the occurrence of mice (MR = 1.39; 95% C.I.: 1.00; 1.93). The season and indoor climate (operative temperature and relative humidity) did not effect endotoxin concentration. These results indicate that high endotoxin concentration in settled dust is an indicator of poor hygienic conditions in homes.

Endotoxin in inner-city homes: Associations with wheeze and eczema in early childhood

“…In NYC, differences in endotoxin among the neighborhoods may reflect the differences in housing stock. Unlike a German study, we did not find any associations with the story of the apartment (30). The same German study also reported higher endotoxin in older buildings (before 1980).…”

“…These findings are in keeping with a German study (30) that found an association with mouse sightings and the U.S. National Home Survey that found an association with cockroach allergen (29). With regression analysis, mouse and cockroach allergens were found to be independently associated with endotoxin; however, these variables combined only explained 11% of the variation in endotoxin.…”

Reproducibility of allergen, endotoxin and fungi measurements in the indoor environment

“…Results on biocontaminant levels of the first home visit of the INGA study have been published previously (Fahlbusch et al, 1999Koch et al, 2000;Heinrich et al, 2001;Bischof et al, 2002;Gro et al, 2001). Here we present the results on repeated measurements of biocontaminants collected in the same homes.…”

Nonallergic respiratory morbidity improved along with a decline of traditional air pollution levels: a review

“…Endotoxin concentrations in living-room floor dust sampled in homes without pets and vermin were lower than those sampled in homes with pets or vermin [24]. Endotoxin concentrations were higher in old buildings and in the lower storey of the dwelling, and were associated with longer occupancy in the apartment, high utilisation of the apartment during the sampling period, infrequent vacuum cleaning of the carpets, and an indifferent attitude to ventilation and keeping cats and dogs [25]. Summarising the results of comparative indoor measurements in Erfurt and Hamburg, it was concluded that despite detected regional differences, these differences probably only contribute a little to the different prevalences in atopic outcomes.…”