Oxidative capacity and hemolytic activity of settled dust from moisture‐damaged schools

Abstract

Exposure to moisture‐damaged indoor environments is associated with adverse respiratory health effects, but responsible factors remain unidentified. In order to explore possible mechanisms behind these effects, the oxidative capacity and hemolytic activity of settled dust samples (n = 25) collected from moisture‐damaged and non‐damaged schools in Spain, the Netherlands, and Finland were evaluated and matched against the microbial content of the sample. Oxidative capacity was determined with plasmid scission assay and hemolytic activity by assessing the damage to isolated human red blood cells. The microbial content of the samples was measured with quantitative PCR assays for selected microbial groups and by analyzing the cell wall markers ergosterol, muramic acid, endotoxins, and glucans. The moisture observations in the schools were associated with some of the microbial components in the dust, and microbial determinants grouped together increased the oxidative capacity. Oxidative capacity was also affected by particle concentration and country of origin. Two out of 14 studied dust samples from moisture‐damaged schools demonstrated some hemolytic activity. The results indicate that the microbial component connected with moisture damage is associated with increased oxidative stress and that hemolysis should be studied further as one possible mechanism contributing to the adverse health effects of moisture‐damaged buildings.

The Toxicity of Wiped Dust and Airborne Microbes in Individual Classrooms Increase the Risk of Teachers’ Work-Related Symptoms: A Cross-Sectional Study

“…Although the immunotoxicity of indoor samples in the mouse RAW264.7 macrophage assay has been described to reduce after the renovation of moisture-damaged schools [31,34], it was not possible to distinguish moisture-damaged schools from control schools with this method [32,35]. The same holds true for hemolytic activity tested on human erythrocytes or oxidative capacity by plasmid scission assay [36].…”

Bioreactivity, Guttation and Agents Influencing Surface Tension of Water Emitted by Actively Growing Indoor Mould Isolates

“…Reduction of the surface tension of water may be caused by anthropogenic chemicals and/or be microbially produced, but surface-active substances exist in much higher airborne concentrations in indoor environments compared to outdoor air [24,25]. Tensiometric measurements and assays measuring plasma membrane damage [48,71] could be used for monitoring surfactant activity in indoor samples, but only chemical analyses could reveal their microbiological or anthropogenic origin [59].…”

The Roles of Autoimmunity and Biotoxicosis in Sick Building Syndrome as a “Starting Point” for Irreversible Dampness and Mold Hypersensitivity Syndrome

“…As reported, air samples were collected from settled dust on cardboard boxes or by electrostatic dust fall collectors [65]. These techniques completely ignore the fact that toxigenic indoor microbes, such as Stachybotrys, emit toxins as liquid vesicles (micro vesicles, exoms) in which the concentrations of toxins are more than 1000-fold higher than the emissions coming from the same microbial particle (spores, hyphae fragments) [66].…”