This paper suggests that very high relative humidity (RH) within walls is a strong risk factor for their infestation with the 'toxic mold' Stachybotrys chartarum. Besides, data from the literature demonstrate that other molds are able to produce mycotoxins when RH is very high. Thus, measurement of wall RH, which is easy to perform and very cheap, could be used as a screening tool to select those dwellings where mold identification should be performed and remediation should be promptly carried out.
The objective of this study was to assess the level of macrocyclic trichothecenes (MCT), one of the most potent mycotoxins, on wall surfaces, floor dust and air samples from moldy dwellings. The study was based on an index group comprising 15 flooded dwellings contaminated by Stachybotrys chartarum or Chaetomium and a control group comprising nine dwellings without molds on visual inspection and mold sampling. Three samples were collected from each dwelling: a sample from the moldy wall, using a swab, a floor dust sample on a 0.5 m(2) surface with a cloth and an air sample using a pump comprising a 1 microm Teflon filter. The MCT level was measured using a monoclonal, antibody-based ELISA test. Compared with measurements performed in index dwellings, higher MCT values were measured on floor dust samples from moldy dwellings (P = 0.02). Samples from wall surfaces demonstrated nearly significant differences (P = 0.06). No significant differences were observed for air samples (P = 0.15), but some samples showed increased MCT levels. Significant correlations were observed between the levels measured on wall surfaces, floor dust and air samples (P = 0.02 to 0.05). In contrast, no correlation was observed between moldy surface and MCT levels. In conclusion, this paper reports for the first time direct evidence for the presence of MCT in moldy dwellings.
Nowadays, flooding occurs more frequently. Although development of mold species depends on environmental conditions, few studies have so far described mold species occurring following flooding in order to compare mold species sampled in flooded dwellings and in unhealthy dwellings. About 185 dwellings flooded in Arles, southern France, on 2-5 December 2003 and 341 unhealthy dwellings. Home inspections included mold sampling using the paper-gummed technique. The prevalence of Alternaria species and Stachybotrys chartarum was much greater (P \ 0.001) in flooded dwellings whereas Aspergillus and Penicillium were more often encountered in unhealthy dwellings (P \ 0.001). Two mold species, namely Alternaria and Stachybotrys chartarum, were over-represented in flooded dwellings. This finding is important because these mold species may produce mycotoxins with a potential health impact.
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