An indoor air quality study of an alligator (Alligator mississippiensis) holding facility.

An environmental microbiologic investigation was conducted in an alligator (Alligator mississippiensis) holding facility in a zoo in the southeastern U.S. The facility had housed five alligators between March 1999 and February 2005. In the exhibit, one alligator died and all experienced poor health. It was hypothesized that environmental microbial contamination was associated with these issues. Samples were collected for fungal identification and quantification, microcystin analysis, and airborne mycotoxins. Analyses of air and water were conducted and an examination of the heating, ventilation, and air-conditioning system (HVAC) for design, maintenance, and operating issues was made. Two control sites, a facility for false gharials (Tomistoma schlegelii) and an off-site alligator breeding facility, were also tested. Morbidity and mortality records were examined for all sites. Results showed that, compared to the control sites, the test alligator facility and its HVAC system were extensively contaminated with a range of fungi. Nearly all sampled surfaces featured fungal growth. There were also significantly higher counts of Penicillium/Aspergillus-like and Chrysosporium-like spores in the air (P < 0.004). The design, maintenance, and operation of the HVAC system were all inadequate, resulting in poorly conditioned and mold-contaminated air being introduced to the facility. Morbidity records revealed solitary pulmonary disorders over time in three alligators, with one dying as a result. The other two alligators suffered from general malaise and a range of nonspecific symptoms. The control facilities had no morbidity or mortality issues. In conclusion, although no causal links could be demonstrated because of the nature of the morbidity data, environmental mold contamination appeared to be associated with the history of morbidity and mortality in the alligator exhibit.

Effect of chlorine dioxide gas on fungi and mycotoxins associated with sick building syndrome.

The growth of indoor molds and their resulting products (e.g., spores and mycotoxins) can present health hazards for human beings. The efficacy of chlorine dioxide gas as a fumigation treatment for inactivating sick building syndrome-related fungi and their mycotoxins was evaluated. Filter papers (15 per organism) featuring growth of Stachybotrys chartarum, Chaetomium globosum, Penicillium chrysogenum, and Cladosporium cladosporioides were placed in gas chambers containing chlorine dioxide gas at either 500 or 1,000 ppm for 24 h. C. globosum was exposed to the gas both as colonies and as ascospores without asci and perithecia. After treatment, all organisms were tested for colony growth using an agar plating technique. Colonies of S. chartarum were also tested for toxicity using a yeast toxicity assay with a high specificity for trichothecene mycotoxins. Results showed that chlorine dioxide gas at both concentrations completely inactivated all organisms except for C. globosum colonies which were inactivated an average of 89%. More than 99% of ascospores of C. globosum were nonculturable. For all ascospore counts, mean test readings were lower than the controls (P < 0.001), indicating that some ascospores may also have been destroyed. Colonies of S. chartarum were still toxic after treatment. These data show that chlorine dioxide gas can be effective to a degree as a fumigant for the inactivation of certain fungal colonies, that the perithecia of C. globosum can play a slightly protective role for the ascospores and that S. chartarum, while affected by the fumigation treatment, still remains toxic.

Efficacy of chlorine dioxide as a gas and in solution in the inactivation of two trichothecene mycotoxins.

The efficacy of chlorine dioxide (ClO2) in detoxifying two potential bioterrorism agents, the trichothecene mycotoxins verrucarin A and roridin A, was evaluated. In the first experiment, verrucarin A (1, 5, or 10 microg) and roridin A (5 or 10 microg) were each inoculated onto square-inch sections of glass, paper, and cloth and exposed to 1000 ppm of ClO2 for either 24 or 72 h at room temperature. In the second experiment, verrucarin A and roridin A (1 or 2 ppm in water) were treated with 200, 500, or 1000 ppm ClO2 for up to 116 h at room temperature in light and dark conditions (N = 9 per treatment for test and control). A yeast assay using Kluyveromyces marxianuswas used to quantify the toxicity of verrucarin A and roridin A. Additionally, high-performance liquid chromatography was performed on selected samples. Results for the first experiment showed that ClO2 treatment had no detectable effect on either toxin. For the second experiment, both toxins were completely inactivated at all tested concentrations in as little as 2 h after treatment with 1000 ppm ClO2. For verrucarin A, an effect was seen at the 500 ppm level, but this effect was not as strong as that observed at the 1000 ppm level. Roridin A toxicity was decreased after treatment with 200 and 500 ppm ClO2, but this was not significant until the 24-h exposure time was reached. These data show that ClO2 (in solution) can be effective for detoxification of roridin A or verrucarin A at selected concentrations and exposure times.

An investigation into techniques for cleaning mold-contaminated home contents.

This study examined the efficacy of the following treatments to reduce selected fungal spore and mycotoxin levels on materials commonly found in home contents: (1) gamma irradiation at a 10-13 kiloGray exposure, (2) a detergent/bleach wash, and (3) a steam cleaning technique. A minimum of six replicates were performed per treatment. Paper, cloth, wood, and carpet were inoculated with either fungal spores (Stachybotrys chartarum, Aspergillus niger, Penicillium chrysogenum, or Chaetomium globosum) at 240,000 spores/2.54 cm2 of material or with the mycotoxins roridin A, T-2, and verrucarin A at 10 microg per 2.54 cm2 of material. Treatments were evaluated with an agar plating technique for fungal spores and a yeast toxicity culture assay for mycotoxins. Results showed that gamma irradiation inactivated fungal spores, but the treatment was not successful in inactivating mycotoxins. The washing technique completely inactivated or removed spores on all materials except for C. globosum, which was reduced on all items except paper (p < 0.05). Washing inactivated all mycotoxins on paper and cloth but not on carpet or untreated wood (p < 0.001). The steam cleaning treatment did not completely eliminate any fungal spores; however, it reduced P. chrysogenum numbers on all materials, C. globosum was reduced on wood and carpet, and S. chartarum was reduced on wood (p < 0.05). Steam cleaning was unsuccessful in inactivating any of the tested mycotoxins. These results show that the bleach/detergent washing technique was more effective overall in reducing spore and mycotoxin levels than gamma irradiation or steam cleaning. However, the other examined techniques were successful in varying degrees.