Determinants of house dust, endotoxin, and beta-(1-->3)-d-glucan in homes of Danish children

Little is known about the geographic variation and determinants of bacterial endotoxin and beta -(1,3)-d-glucan in Danish house dust. In a population of 317 children, we: (i) described loads and concentrations of floor dust, endotoxin, and beta-(1-->3)-d-glucan and (ii) their correlations and (iii) assessed their determinants; (iv) Finally, we compared our findings with previous European studies. Bedroom floor dust was analyzed for endotoxin content by the kinetic limulus amoebocyte lysate assay and for beta-(1-->3)-d-glucan by the inhibition enzyme immunoassay. The parents answered questions regarding potential determinants. We found: geometric means (geometric standard deviations) 186 mg/m2 (4.3) for dust; 5.46 x 103 EU/m2 (8.0) and 31.1 x 103 EU/g (2.6) for endotoxin; and 142 mug/m2 (14.3) and 0.71 x 103 mug/g (7.3) for beta-(1-->3)-d-glucan. High correlations (r > 0.75) were found between floor dust and endotoxin and beta-(1-->3)-d-glucan loads, while endotoxin and beta-(1-->3)-d-glucan concentrations were moderately correlated (r = 0.36-0.41) with the dust load. Having a carpet was positively associated with dust load and with endotoxin and beta-(1-->3)-d-glucan concentrations. Pet keeping, dwelling type, and dwelling location were determinants of endotoxin concentrations. No other determinants were associated with beta-(1-->3)-d-glucan concentrations. Compared with other European studies, we found lower beta-(1-->3)-d-glucan loads and concentrations but higher endotoxin loads and concentrations suggesting a geographically determined different composition of Danish floor dust compared with other European regions