Acute effects of Aspergillus versicolor aerosols on murine airways.

Mice were exposed to aerosols from Aspergillus versicolor extract by inhalation (for 15-20 min). Changes in respiratory function parameters were monitored during the exposure to evaluate acute effects on the upper and lower respiratory tracts and the conductive airways. The single inhalation exposure to A. versicolor aerosols at the range of 12-151 mg/m3 provoked upper respiratory tract irritation in the airways of mice. The higher the exposure concentration the higher was the increase in the sensory irritation (SI) response. No bronchoconstriction or pulmonary irritation was observed. The causative agents for the SI response in the fungal extract are not known.

Slight respiratory irritation but not inflammation in mice exposed to (1-->3)-beta-D-glucan aerosols.

Airway irritation effects after single and repeated inhalation exposures to aerosols of beta-glucan (grifolan) were investigated in mice. In addition, the effects on serum total immunoglobulin E (IgE) production and histopathological inflammation in the respiratory tract were studied. The beta-glucan aerosols provoked slight sensory irritation in the airways, but the response was not concentration dependent at the levels studied. Slight pulmonary irritation was observed after repeated exposures. No effect was found on the serum total IgE levels, and no signs of inflammation were seen in the airways 6 h after the final exposure. The results suggest that, irrespective of previous fungal sensitization of the animals, inhaled beta-glucan may cause symptoms of respiratory tract irritation but without apparent inflammation. Respiratory tract irritation reported after inhalation of fungi may not be entirely attributed to beta-glucan.

The effects of wood dusts on the redox status and cell death in mouse macrophages (RAW 264.7) and human leukocytes in vitro.

Wood dusts are classified as carcinogenic to humans and also produce other toxic, allergic, and acute effects in woodworkers. However, little is known about causative agents in wood dusts and their mechanisms of action. The effects of different tree species and particle size for biological activity were studied. The differences in the production of reactive oxygen species (ROS) and cell death (necrotic and apoptotic) between mouse macrophage (RAW 264.7) cells and human polymorphonuclear leukocytes (PMNL) for pine, birch, and beech dust exposures were investigated in vitro. The pine and birch dust exposure (1-100 microg/ml) produced concentration-dependent ROS production in both the cells, which was one order of magnitude higher with pine dust. The ROS production was faster in human PNML than murine RAW cells. The higher concentrations (500 and/or 1000 microg/ml) decreased ROS formation. With pine and birch dust exposure, this was probably due to the necrotic cell death. The pine dust concentrations of 500 and 1000 microg/ml were cytotoxic to human PMNL. The beech dust exposure activated the ROS production and decreased the cell viability only at the highest concentrations, being least potent of the three dusts. A sign of the apoptotic cell death in the murine RAW cells was observed at the pine dust concentration of 100 microg/ml. The exposure to the birch and beech dusts with a smaller particle size (<5 microm) produced greater ROS production than exposure to the corresponding dust with a wide range of particle sizes. However, changing the particle size did not affect the cell viability. The results indicate that the type of wood dust (tree species and possibly particle size) has a significant impact on the function and viability of phagocytic cells.

Effects of aerosols from nontoxic Stachybotrys chartarum on murine airways.

Acute effects on the upper and lower respiratory tract due to inhalation exposure to Stachybotrys chartarum (Sc) extract were investigated in mice. In addition, the capacity of the Sc exposure to activate immune system and cause inflammation in the respiratory tract was studied. The inhalation of Sc extract aerosols was observed to provoke sensory irritation in the airways of both naive and Sc-immunized mice. In contrast, exposure to aerosolized ovalbumin or phosphate buffered saline did not cause this effect. Exposure to Sc twice a week for 3 wk increased significantly the serum total immunoglobulin E (IgE) levels in BALB/c mice immunized with Sc as well as in nonimmunized mice. A slight presence of inflammatory cells was observed in the alveoli 3 days after the last exposure to Sc. In conclusion, Sc extract has the capacity to provoke sensory irritation in the murine airways and to activate the murine immune system.

The relationship between measured moisture conditions and fungal concentrations in water-damaged building materials.

We determined the moisture levels, relative humidity (RH) or moisture content (MC) of materials, and concentrations of culturable fungi, actinomycetes and total spores as well as a composition of fungal flora in 122 building material samples collected from 18 moisture problem buildings. The purpose of this work was to clarify if the is any correlation between the moisture parameters and microbial levels or generic composition depending on the type of materials and the time passed after a water damage. The results showed an agreement between the concentrations of total spores and culturable fungi for the wood, wood-based and gypsum board samples (r > 0.47). The concentrations of total spores and/or culturable fungi correlated with RH of materials particularly among the wood and insulation materials (r > 0.79), but not usually with MC (r < 0.45). For the samples collected from ongoing damage, there was a correlation between RH of materials and the concentrations of total spores and culturable fungi (r > 0.51), while such a relationship could not be observed for the samples taken from dry damage. A wide range of fungal species were found in the samples from ongoing damage, whereas Penicillia and in some cases yeasts dominated the fungal flora in the dry samples. This study indicates that fungal contamination can be evaluated on the basis of moisture measurements of constructions in ongoing damage, but the measurements are not solely adequate for estimation of possible microbial growth in dry damage.

Sensory irritating potency of some microbial volatile organic compounds (MVOCs) and a mixture of five MVOCs.

The authors investigated the ability/potencies of 3 microbial volatile organic compounds and a mixture of 5 microbial volatile organic compounds to cause eye and upper respiratory tract irritation (i.e., sensory irritation), with an animal bioassay. The authors estimated potencies by determining the concentration capable of decreasing the respiratory frequency of mice by 50% (i.e., the RD50 value). The RD50 values for 1-octen-3-ol, 3-octanol, and 3-octanone were 182 mg/m3 (35 ppm), 1359 mg/m3 (256 ppm), and 17586 mg/m3 (3360 ppm), respectively. Recommended indoor air levels calculated from the individual RD50 values for 1-octen-3-ol, 3-octanol, and 3-octanone were 100, 1000, and 13000 microg/m3, respectively-values considerably higher than the reported measured indoor air levels for these compounds. The RD50 value for a mixture of 5 microbial volatile organic compounds was also determined and found to be 3.6 times lower than estimated from the fractional concentrations and the respective RD50s of the individual components. The data support the conclusion that a variety of microbial volatile organic compounds may have some synergistic effects for the sensory irritation response, which constrains the interpretation and application of recommended indoor air levels of individual microbial volatile organic compounds. The results also showed that if a particular component of a mixture was much more potent than the other components, it may dominate the sensory irritation effect. With respect to irritation symptoms reported in moldy houses, the results of this study indicate that the contribution of microbial volatile organic compounds to these symptoms seems less than previously supposed.

Evaluation of sensory irritation of delta3-carene and turpentine, and acceptable levels of monoterpenes in occupational and indoor environment.

The standard mouse bioassay was used for obtaining the RD50 (i.e., the concentration that causes a 50% decrease in respiratory frequency) and for estimating the irritation properties of d-delta3-carene (i.e., (+)-delta3-carene) and commercial turpentine. The chemicals studied possess mainly sensory irritation properties similar to the previously studied monoterpenes, pinenes. The irritation potency of d-delta3-carene (RD50 = 1345 ppm) was almost equal to that of d-pinenes. Thus, d-delta3-carene was about four times more potent as a sensory irritant than I-beta-pinene, whereas the difference with I-alpha-pinene was more marked; as a sensory irritant, I-alpha-pinene is almost inactive. Based on sensory irritation potency and physicochemical and structural properties of pinenes and delta3-carene, the potency of a closely related monoterpene, limonene, is discussed. For commercial turpentine, a mixture of monoterpenes (mainly d-delta3-carene, I-beta-pinene, alpha-pinenes, and limonenes), the RD50 (1173 ppm) was the same order of magnitude as those of d-pinenes and d-delta3-carene. Apparently, d-monoterpenes are responsible for the sensory irritation caused by turpentine. In the wood industry and in the indoor air of nonindustrial environments, monoterpenes are thought to be one of the causative agents for irritation symptoms. The occupational exposure limit (OEL) of turpentine (100 ppm in Finland and the United States) is also used for individual monoterpenes, excluding limonene. Using results from this and our previous study, proposed OELs and recommended indoor levels (RILs) for selected monoterpenes and turpentine were determined based on their RD50 values. According to our studies, the present OEL of turpentine (100 ppm; 560 mg/m3) in Finland and in the United States seems to be suitable only for I-pinenes. For d-monoterpenes and turpentine, an OEL about three times lower is suggested. Our results show that recommended indoor levels (RILs) for monoterpenes are high compared to the concentrations measured indoors in nonindustrial environments. Thus, it is very unlikely that monoterpenes alone can cause irritation symptoms in homes or offices under normal conditions.

Stereospecificity of the sensory irritation receptor for nonreactive chemicals illustrated by pinene enantiomers.

To clarify the existence of a receptor protein for sensory irritants in trigeminal nerve endings, D- [i.e. (+)] and L- [i.e. (-)] enantiomers of alpha- and beta-pinene as models of nonreactive chemicals were evaluated for their potency in outbred OF1 and NIH/S mice using ASTM E981-84 bioassay. All pinenes possess sensory irritation properties and also induced sedation and signs of anaesthesia but had no pulmonary irritation effects. According to the ratio of RD50 (i.e. concentration which causes a 50% decrease in respiratory rate,f) and vapour pressure (Po), all pinenes are nonreactive chemicals. For nonreactive chemicals, Po and olive oil-gas partition (Loil) can be used to estimate their potency as sensory irritant. Thus, for enantiomers with identical physicochemical properties, the estimated RD50 values are the same. In addition, although alpha- and beta-pinene do not have identical Po and Loil values, their estimated potencies are quite close. However, the experimental results showed that D-enantiomers of pinenes were the most potent as sensory irritants and a difference in potency also exists between alpha- and beta-pinene. RD50 for D-enantiomers of alpha- and beta-pinene were almost equal, 1053 ppm and 1279 ppm in OF1 strain and 1107 ppm and 1419 ppm in NIH/S strain, respectively. Values differed by a factor of approximately 4 to 5 from L-beta-pinene for which the RD50 was 4663 ppm in OF1 and 5811 ppm in NIH/S mice. RD50 could not be determined for L-alpha-pinene; this pinene was almost inactive. D-alpha-pinene seems to best fit the receptor because its experimental RD50 was one-half of the estimated value while for D-beta-pinene those values were equal. On the contrary, L-beta-pinene was about 3 to 4 times less potent than estimated. L-alpha-pinene was only slightly active although it was estimated to be as potent as D-alpha-pinene. The remarkable difference in potency between L-enantiometers is most likely due to a structural difference between alpha- and beta-pinene: the more flexible beta-pinene can bend to fit into the receptor better than the rigid alpha-pinene. The results showed that the commonly used physicochemical descriptors cannot fully explain the potency of these chemicals; their three-dimensional structure should also be considered. Because of the stereospecificity of pinenes, a target site for nonreactive sensory irritants is most likely a receptor protein containing a chiral lipophilic pocket.