Respiratory Effects in Mice Exposed to Airborne Emissions fromStachybotrys chartarumand Implications for Risk Assessment

Abstract

Stachybotrys charfarum, a mycotoxin producing mould found in some damp buildings, was grown in aluminum dishes in closed exposure chambers. The loading factor, 5.12 m2/m3, corresponded to 2.8 times the loading in a normal room with all surfaces covered by mould. Sensory irritation, bronchoconstriction and pulmonary irritation effects were investigated using a sensitive mouse bioassay in which the airway reactions were measured plethysmographically. Little effect was seen from the vapours in agreement with the predicted effects of the low concentrations of volatile organic compounds measured. Even under the influence of an airflow about four times that measured in normal buildings, the concentration of liberated spores and other particles was very low, corresponding to the biological effects observed, and probably reflecting the high water content of the substrate. These results demonstrate that many factors are important for the transport of biologically active mould metabolites from building material to occupants and that no direct relationship may exist between immediate biological effects and surface area covered with mould. Therefore, risk assessments should be based on estimated effects of emitted vapours, effects of liberated particles, e.g. sensitization potentials of the mould spores and effects of the generated metabolites (mycotoxins).

Indoor Mold, Toxigenic Fungi, andStachybotrys chartarum: Infectious Disease Perspective

“…Spores or fragments probably need to be Ͻ1 m in diameter to reach the lower respiratory tract by airborne exposure, and Stachybotrys spores are much larger than this. While intranasal instillation of spores causes them to be flushed into the lungs (296, 297), it does not reflect human exposure conditions (61)(62)(63)(64)445). This may explain why effects seen in murine experimental models have not been seen in humans.…”

“…Furthermore, the response to toxigenic spores is different from the response to toxins alone (296), and probably only the latter is physiologically relevant. In one of the only studies using a relevant model, Wilkins et al (445) grew Stachybotrys in an open dish in a closed chamber (to mimic human exposure) and examined acute murine pulmonary toxicity by a bioassay of respiratory parameters. The estimated exposure level was nearly three times estimated human levels (the satratoxin H level was Ն100 g/dish).…”

“…However, this is based on work involving extensively processed spores, which are of questionable relevance to actual exposure conditions (397). In more appropriate models, even if spores are liberated, it is unlikely they reach the lower airways due to their size (445). Stachybotrys spores are single-celled ellipsoid structures 5 to 7 by 8 to 12 m in size (144).…”

Detection of AirborneStachybotrys chartarumMacrocyclic Trichothecene Mycotoxins in the Indoor Environment

“…chartarum airborne mycotoxins have been studied in various laboratory settings (4,34,44,47) and are known to be detrimental in several animal models (32,37,49). However, research that effectively demonstrates the presence of airborne S. chartarum trichothecene mycotoxins in native indoor environments is lacking.…”

Toxic and other non-IgE-mediated effects of fungal exposures

“…The effects of passive inhalation of Stachybotrys were investigated in a mouse model. Mice were placed in a cham- [37]. Stachybotrys has been associated with toxicity, or stachybotryotoxicosis, via several routes, including contact, ingestion, or inhalation.…”