Determinants of endotoxin levels in carpets in New Zealand homes

Abstract

Endotoxin in house dust has been shown to be associated with asthma severity. Little is known about the influence of housing characteristics on endotoxin distribution. Using standardized methods, dust was sampled from a 1m(2) site and the whole accessible carpet area in selected Wellington, New Zealand homes (n = 77). Endotoxin was measured using a Limulus Amoebocyte Lysate assay. Relative humidity and temperature were recorded using sensors placed in carpet bases. Questionnaires were used to collect information on housing characteristics. All analyses were performed for endotoxin units (EU)/mg and EU/m2 for each site. Geometric mean endotoxin levels were 22.7 EU/mg [geometric standard deviation (GSD) = 2.4] or 30,544 EU/m2 (GSD = 3.2) from the 1m(2) site, and 28.4 EU/mg (GSD = 3.4) or 5653 EU/m2 (GSD = 6.4) from the whole room. After controlling for confounding, endotoxin was positively associated with dogs inside [geometric mean ratio (GMR): 0.9-2.0], total household occupants (GMR: 1.7-2.0, for 1 m2 sample only), vacuum cleaners <1-year old (GMR: 2.3-2.7), reusing vacuum dust collection bags (GMR: 1.4-3.1), steamcleaning or shampooing the carpet (GMR: 1.4-2.2) and high relative humidity (GMR: 1.4-1.6). Lower endotoxin was associated with floor insulation (GMR: 0.4-0.8), and north-facing living rooms (GMR: 0.4-0.8). This study has identified home characteristics that could be modified to reduce endotoxin exposure.

Children’s residential exposure to selected allergens and microbial indicators: endotoxins and (1→3)-β-D-glucans

“…The mean levels of endotoxins found in the USA and in Germany were slightly higher than ours [26][27][28][29][30]. Slightly lower concentrations were observed in several studies from Europe, New Zealand, and Canada [23,[31][32][33][34][35]. Our results indicate that the concentration of endotoxins present in settled dust depends significantly on the type of floor.…”

Gene-environment interactions with CD14 C-260T and their relationship to total serum IgE levels in adults

“…Evidence showing that pet ownership is associated with higher house dust endotoxin levels [17][18][19]26 and the finding that children with both the TT genotype at CD14 2260 and dogs at home were least likely to have atopic dermatitis 27 suggested that the effect of pets might be mediated through endotoxin exposure. However, we did not observe a significant interaction between the CD14 2260 genotype and measures of pet exposure, nor were these interactions similar to the interaction observed for CD14 C-260T genotype and endotoxin exposure.…”

Microbial exposure of rural school children, as assessed by levels of N-acetyl-muramic acid in mattress dust, and its association with respiratory health☆

“…The presence of pets, 14,15 an increasing number of household occupants, older vacuum cleaners, a high relative humidity, and the absence of floor insulation were associated with increased endotoxin concentrations in settled household dust. 15 Endotoxin, however, represents only a part of the total microbial burden, because it occurs only in gram-negative bacteria. Peptidoglycan, in turn, is a major component of the cell wall of all species of the domain Bacteria, but not in species of the domain Archaea.…”