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Associations between house dust-associated beta-(1,3)-glucan exposure and airway inflammatory reactions have been reported, while such exposures in early childhood have been suggested to protect against asthma and wheezing. Most epidemiological studies have used reservoir dust samples and an inhibition enzyme immunoassay (EIA) for beta-(1,3)-glucan exposure assessment. The objective of this study was to develop inexpensive but highly sensitive enzyme immunoassays to measure airborne beta-(1,3)-glucans in low-exposure environments, like homes. Specificities of available anti-beta-(1,3)-glucan antibodies were defined by direct and inhibition experiments. Three suitable antibody combinations were selected for sandwich EIAs. beta-(1,3)-Glucans in passive airborne dust collected with an electrostatic dust fall collector (EDC) and floor dust from seven homes were measured with the three EIAs. Floor dust samples were additionally analyzed in the inhibition EIA. The sandwich EIAs were sensitive enough for airborne glucan measurement and showed different specificities for commercial glucans, while the beta-(1,3)-glucan levels in house dust samples correlated strongly. The feasibility of measuring glucans in airborne dust with the recently introduced EDC method was further investigated by selecting the most suitable of the three EIAs to measure and compare beta-(1,3)-glucan levels in the EDC and in floor and actively collected airborne dust samples of the previously performed EDC validation study. The EDC beta-(1,3)-glucan levels correlated moderately with beta-(1,3)-glucans in actively collected airborne dust and floor dust samples, while the glucan levels in the airborne dust and floor dust samples did not correlate. The combination of the newly developed beta-(1,3)-glucan sandwich EIA with EDC sampling now allows assessment in large-scale population studies of exposure to airborne beta-(1,3)-glucans in homes or other low-exposure environments.

The measurement of airborne endotoxins is thus far not standardized. Earlier studies reported higher endotoxin yields when Tween 20 was added to the media used for filter extraction and in the Limulus amebocyte lysate (LAL) assay. This study compared four common media and assessed the effects of Tween during extraction and analysis separately. Parallel airborne dust samples from five work environments (n = 250) were used to compare the four media (pyrogen-free water [PFW], PFW-Tween 20, PFW-Tris, and PFW-triethylamine-phosphate [TAP]) and an extraction time of 10 or 60 min. A subset of the extracts in PFW or PFW-Tween (n = 40) were analyzed in parallel LAL assays with PFW or PFW-Tween as the assay medium. The results produced by a shorter extraction time or the presence of Tris were similar to the results for the reference procedure (PFW and 60 min of shaking). The use of PFW-TAP showed overall lower yields and a deviant calibration curve. The presence of Tween in the extraction medium resulted in significantly (P < 0.05) higher endotoxin yields from all dust types, independent of the effect of Tween in the assay. Tween in the LAL assay, however, also strongly inhibited the reactivity of the lipopolysaccharide (LPS) standard, thus shifting the calibration curve to higher values. The inhibition of LPS in test samples was less pronounced and varied between dust sources, resulting in enhanced calculated concentrations. This assay effect could be circumvented by diluting extracts at least 50-fold before the LAL assay. In conclusion, of the media tested, only Tween enhances the efficiency of endotoxin extraction from airborne dust samples in a consistent manner. We recommend extraction in PFW-Tween combined with dilution and LAL analysis in PFW.

As part of environmental management policies in Europe, separate collection of organic household waste and nonorganic household waste has become increasingly common. As waste is often stored indoors, this policy might increase microbial exposure in the home environment. In this study we evaluated the association between indoor storage of organic waste and levels of microbial agents in house dust. The levels of bacterial endotoxins, mold beta(1-->3)-glucans, and fungal extracellular polysaccharides (EPS) of Aspergillus and Penicillium species were determined in house dust extracts as markers of microbial exposure. House dust samples were collected in 99 homes in The Netherlands selected on the basis of whether separated organic waste was present in the house. In homes in which separated organic waste was stored indoors for 1 week or more the levels of endotoxin, EPS, and glucan were 3.2-, 7.6-, and 4. 6-fold higher, respectively (all P < 0.05), on both living room and kitchen floors than the levels in homes in which only nonorganic residual waste was stored indoors. Increased levels of endotoxin and EPS were observed, 2.6- and 2.1-fold (P < 0.1), respectively, when separated organic waste was stored indoors for 1 week or less, whereas storage of nonseparated waste indoors had no effect on microbial agent levels (P > 0.2). The presence of textile floor covering was another major determinant of microbial levels (P < 0.05). Our results indicate that increased microbial contaminant levels in homes are associated with indoor storage of separated organic waste. These increased levels might increase the risk of bioaerosol-related respiratory symptoms in susceptible people.