Characterization of lipopolysaccharides in settled house dust.
Park J; Szponar B; Larsson L; Gold D; Milton D
American Industrial Hygiene Conference and Exposition, June 1-6, 2002, San Diego, California. Fairfax, VA: American Industrial Hygiene Association, 2002 Jun; :93
Chain-lengths of 3-hydroxy fatty acids (3-OHFAs) in the lipid-A portion of LPS vary with the type of bacteria. We used GC-MS to assay 190 house dust (HD) samples for 3-OHFAs to determine whether LPS in HD varies qualitatively and quantitatively within the home and between seasons. Dust samples from beds, bedroom floors, family rooms, and kitchen floors were collected as part of a birth-cohort study of childhood asthma (Study 1), and a longitudinal study of home allergens/endotoxin (Study 2). We also analyzed endotoxin activity (EA) by Limulus assay. Longer-chain 3-OHFAs (CI6:0 and C18:0) comprised 64% (Study 1) and 71% (Study 2) of the 3-OHFAs in HD. However, in the pooled data, EA was significantly (p<0.001) and more strongly correlated with short-chain (r=0.28, 0.29, and 0.35 for C10:0, C12:0, and C14:0, respectively) than with long-chain 3-OHFAs. This implies that the Limulus assay responds preferentially to LPS containing short-chain 3-OHFAs, and is not sensitive to the presence of LPS composed of long-chain 3-OHFAs. In addition, for Study 2, LPS in bed dust showed higher amounts of long-chain 3-OHFAs (p<0.01), and lower EA (p<0.000l) and lower potency (EU/nmole LPS: p<0.000l) than LPS in kitchen-floor dust; bed dust was not available from Study 1. However, kitchen-floor dust had the lowest percentage of long-chain 3-OHFAs, was characterized by increased amounts of short-chain 3-OHFAs, and had the highest EA (p-values<0.02) and potency (p-values<0.005) among all sample types. In both studies, short-chain 3-OHFAs concentrations were lowest in winter and similar during the other seasons; the amount of long-chain 3-OHFAs was highest in the fall. Thus, the distribution of different chain-length LPS may vary within the home and between seasons. The EA measured by Limulus assay may underestimate exposure, especially in bed dust where long chain 3- OHFAs predominate, if the LPS with long- chain 3-OHFAs have important biological effects in humans.
Polysaccharides; Fatty-acids; Bacteria; Dust-particles; Dust-sampling; Allergens; Endotoxins; Biological-effects; Humans; Children; Seasonal-factors; Respiratory-system-disorders; Bacterial-dusts; Bioassays
Work Environment and Workforce: Indoor Environment
American Industrial Hygiene Conference and Exposition, June 1-6, 2002, San Diego, California