Increased incidence of allergic sensitisation and respiratory diseases due to mould exposure: results of the Leipzig Allergy Risk children Study (LARS)

Misalignment between Clinical Mold Antigen Extracts and Airborne Molds Found in Water-Damaged Homes

RATIONALE

Epidemiologic studies have demonstrated that exposure to molds and other fungi can play a role in a variety of allergic and pulmonary diseases in susceptible individuals. Species-specific mold antigen extracts are used in the clinical evaluation of suspected mold-related conditions, however alignment between these extracts and the species of molds identified in the indoor environment of water-damaged homes has not been rigorously evaluated.

OBJECTIVES

To identify the predominant genera and species of mold in the air of homes with water damage, mold growth, and/or occupants with respiratory complaints (complaint homes), and to assess their alignment with the mold antigen extracts used in clinical practice.

METHODS

The genera and species of molds identified in culture-type outdoor and indoor air samples collected from complaint homes throughout the U.S. and Canada from 2002-2017 were examined. Mold antigen extracts available and utilized for skin and serum testing in clinical practice were assessed and alignment between these data were evaluated.

RESULTS

Culture data from 24,455 indoor air samples from 7,547 complaint homes and 29,493 outdoor samples was evaluated. Mean exposure values (CFU/m3) were calculated for each genus and species, and indoor vs outdoor values compared. Penicillium was the predominant genus identified in water-damaged homes, with a mean exposure (233.3 CFU/m3) 2.9 times higher than that of the Aspergillus genus (81.4 CFU/m3). Five Penicillium (P. aurantiogriseum, P. brevicompactum, P. citrinum, P. crustosum, and P. variabile) and three Aspergillus (A. versicolor, A. sydowii, and A. niger) species were identified as the predominant indoor water-damage related fungi. However, none of these Penicillium species and only one of the Aspergillus species is currently available as an antigen extract for use in skin testing or serum testing panels.

CONCLUSIONS

Significant misalignment exists between the currently available mold antigen extracts and the predominant species of molds found in water-damaged homes. Improving alignment has the potential to enhance diagnosis of mold-related diseases including allergic asthma and hypersensitivity pneumonitis and to improve patient outcomes via interventions including antigen avoidance through building remediation and occupant relocation, consistent with the findings of a recent ATS Workshop Report.

Associations between household airborne culturable fungi and allergies and airway illnesses in childhood in Shanghai, China

Associations of household airborne fungi with allergies in childhood were inconsistent in the epidemiologic studies. During 2013-2014, we conducted a case-control study (phase two), which was nested in a cross-sectional study (phase one) during 2011-2012 in Shanghai, China. We inspected indoor air quality of 454 residences for 5-10 years old children. We defined cases as those children who were reported illnesses in the questionnaire of phase one or phase two and defined controls as those children who were not reported illnesses in both phases. A total of 436 living rooms and 445 bedrooms had valid data of household airborne fungi, and their mean concentrations were 301 cfu/m³ and 310 cfu/m³, respectively. In the multiple logistic regression analyses with adjusting for potential confounders, most associations of 16 studied illnesses with airborne fungi concentration were not statistically significant. Taking children in the 1st quartile that was stratified according to airborne fungi concentration in the living room as reference, only children in the 3rd quartile were significantly associated with a higher odd of lifetime-ever ear infections (adjusted OR, 95% CI 3.05, 1.29-7.21), and children in the 4th quartile were significantly associated with a higher odd of lifetime-ever wheeze (2.72, 1.28-5.75); but children in the 3rd quartile (0.33, 0.17-0.68) and in the 4th quartile (0.47, 0.23-0.97) were significantly associated with a lower odd of rhinitis in the past 12 months prior to the home inspection. Our results indicate that exposures to indoor airborne fungi in low concentrations seemingly have no significant impacts on the risks of most allergic and airway illnesses in childhood. Since families with sick participants might pay more attention to improve indoor air quality, effects of "avoidance behavior" on associations between indoor pollutants and childhood health should be considered in the data analysis and design of the nested case-control study.

Characterization and pro-inflammatory potential of indoor mold particles

A number of epidemiological studies find an association between indoor air dampness and respiratory health effects. This is often suggested to be linked to enhanced mold growth. However, the role of mold is obviously difficult to disentangle from other dampness-related exposure including microbes as well as non-biological particles and chemical pollutants. The association may partly be due to visible mycelial growth and a characteristic musty smell of mold. Thus, the potential role of mold exposure should be further explored by evaluating information from experimental studies elucidating possible mechanistic links. Such studies show that exposure to spores and hyphal fragments may act as allergens and pro-inflammatory mediators and that they may damage airways by the production of toxins, enzymes, and volatile organic compounds. In the present review, we hypothesize that continuous exposure to mold particles may result in chronic low-grade pro-inflammatory responses contributing to respiratory diseases. We summarize some of the main methods for detection and characterization of fungal aerosols and highlight in vitro research elucidating how molds may induce toxicity and pro-inflammatory reactions in human cell models relevant for airway exposure. Data suggest that the fraction of fungal hyphal fragments in indoor air is much higher than that of airborne spores, and the hyphal fragments often have a higher pro-inflammatory potential. Thus, hyphal fragments of prevalent mold species with strong pro-inflammatory potential may be particularly relevant candidates for respiratory diseases associated with damp/mold-contaminated indoor air. Future studies linking of indoor air dampness with health effects should assess the toxicity and pro-inflammatory potential of indoor air particulate matter and combined this information with a better characterization of biological components including hyphal fragments from both pathogenic and non-pathogenic mold species. Such studies may increase our understanding of the potential role of mold exposure.

Relationship between mold exposure, specific IgE sensitization, and clinical asthma: A case-control study

BACKGROUND

Most of the findings related to the noxious effect of mold sensitization on asthma come from investigations based on Alternaria alternata, Cladosporium herbarum, and Aspergillus fumigatus. However, species such as Penicillium spp, Cladosporium sphaerospermum, Cladosporium cladosporioides, or Aspergillus versicolor display a more pronounced indoor tropism, and their potential harmful respiratory effects cannot be neglected.

OBJECTIVE

The goal of this work was to relate mold sensitizations with asthma severity and with the level of indoor mold contamination among mold-sensitized patients with asthma and nonsensitized patients with asthma.

METHODS

A case-control study was conducted and several asthma severity markers were compared between patients with asthma with and without mold sensitization. Indoor contamination of patients' dwellings was also investigated.

RESULTS

Our findings confirmed the association between sensitization to A fumigatus and severity for patients with asthma in contrast with sensitization to other species. Indoor mold contamination was detected in approximately 90% of dwellings. Overall mold exposure was not associated with asthma severity. However, regardless of the sensitization, exposure to A fumigatus and Penicillium spp in dust was linked to an increased risk of severe asthma.

CONCLUSION

The harmful nature of mold sensitization and mold exposure for patients with asthma was not confirmed in this study. However, sensitization to A fumigatus was associated with an increased risk for severe asthma. A better investigation of the properties of Penicillium spp is recommended because its exposure was found to be associated with a more pronounced impairment of lung function.

Mold and Human Health: a Reality Check

There are possibly millions of mold species on earth. The vast majority of these mold spores live in harmony with humans, rarely causing disease. The rare species that does cause disease does so by triggering allergies or asthma, or may be involved in hypersensitivity diseases such as allergic bronchopulmonary aspergillosis or allergic fungal sinusitis. Other hypersensitivity diseases include those related to occupational or domiciliary exposures to certain mold species, as in the case of Pigeon Breeder's disease, Farmer's lung, or humidifier fever. The final proven category of fungal diseases is through infection, as in the case of onchomycosis or coccidiomycosis. These diseases can be treated using anti-fungal agents. Molds and fungi can also be particularly important in infections that occur in immunocompromised patients. Systemic candidiasis does not occur unless the individual is immunodeficient. Previous reports of "toxic mold syndrome" or "toxic black mold" have been shown to be no more than media hype and mass hysteria, partly stemming from the misinterpreted concept of the "sick building syndrome." There is no scientific evidence that exposure to visible black mold in apartments and buildings can lead to the vague and subjective symptoms of memory loss, inability to focus, fatigue, and headaches that were reported by people who erroneously believed that they were suffering from "mycotoxicosis." Similarly, a causal relationship between cases of infant pulmonary hemorrhage and exposure to "black mold" has never been proven. Finally, there is no evidence of a link between autoimmune disease and mold exposure.

Medical diagnostics for indoor mold exposure

In April 2016, the German Society of Hygiene, Environmental Medicine and Preventative Medicine (Gesellschaft für Hygiene, Umweltmedizin und Präventivmedizin (GHUP)) together with other scientific medical societies, German and Austrian medical societies, physician unions and experts has provided an AWMF (Association of the Scientific Medical Societies) guideline 'Medical diagnostics for indoor mold exposure'. This guideline shall help physicians to advise and treat patients exposed indoors to mold. Indoor mold growth is a potential health risk, even without a quantitative and/or causal association between the occurrence of individual mold species and health effects. Apart from the allergic bronchopulmonary aspergillosis (ABPA) and the mycoses caused by mold, there is only sufficient evidence for the following associations between moisture/mold damages and different health effects: Allergic respiratory diseases, asthma (manifestation, progression, exacerbation), allergic rhinitis, exogenous allergic alveolitis and respiratory tract infections/bronchitis. In comparison to other environmental allergens, the sensitizing potential of molds is estimated to be low. Recent studies show a prevalence of sensitization of 3-10% in the total population of Europe. The evidence for associations to mucous membrane irritation and atopic eczema (manifestation, progression, exacerbation) is classified as limited or suspected. Inadequate or insufficient evidence for an association is given for COPD, acute idiopathic pulmonary hemorrhage in children, rheumatism/arthritis, sarcoidosis, and cancer. The risk of infections from indoor molds is low for healthy individuals. Only molds that are capable to form toxins can cause intoxications. The environmental and growth conditions and especially the substrate determine whether toxin formation occurs, but indoor air concentrations are always very low. In the case of indoor moisture/mold damages, everyone can be affected by odor effects and/or impairment of well-being. Predisposing factors for odor effects can be given by genetic and hormonal influences, imprinting, context and adaptation effects. Predisposing factors for impairment of well-being are environmental concerns, anxieties, conditioning and attributions as well as a variety of diseases. Risk groups that must be protected are patients with immunosuppression and with mucoviscidosis (cystic fibrosis) with regard to infections and individuals with mucoviscidosis and asthma with regard to allergies. If an association between mold exposure and health effects is suspected, the medical diagnosis includes medical history, physical examination, conventional allergy diagnosis, and if indicated, provocation tests. For the treatment of mold infections, it is referred to the AWMF guidelines for diagnosis and treatment of invasive Aspergillus infections. Regarding mycotoxins, there are currently no validated test methods that could be used in clinical diagnostics. From the perspective of preventive medicine, it is important that mold damages cannot be tolerated in indoor environments.

Does Spore Count Matter in Fungal Allergy?: The Role of Allergenic Fungal Species

Purpose

Fungi have been known to be important aeroallergens for hundreds of years. Most studies have focused on total fungal concentration; however, the concentration of specific allergenic fungi may be more important on an individual basis.

Methods

Ten fungal allergic patients and 2 non-fungal allergic patients were enrolled. The patients with a decrease in physician or patient global assessment by more than 50% of their personal best were considered to have an exacerbation of allergic symptoms and to be in the active stage. Those who maintained their physician and patient global assessment scores at their personal best for more than 3 months were considered to be in the inactive stage. The concentrations of dominant fungi in the patients' houses and outdoors were measured by direct and viable counts at active and inactive stages.

Results

The exacerbation of allergic symptoms was not correlated with total fungal spore concentration or the indoor/outdoor ratio (I/O). Specific fungi, such as Cladosporium oxysporum (C. oxyspurum), C. cladosporioides, and Aspergillus niger (A. niger), were found to be significantly higher concentrations in the active stage than in the inactive stage. Presumed allergenic spore concentration threshold levels were 100 CFU/m³ for C. oxysporum, and 10 CFU/m³ for A. niger, Penicillium brevicompactum and Penicillium oxalicum.

Conclusions

The major factor causing exacerbation of allergic symptoms in established fungal allergic patients may be the spore concentration of specific allergenic fungi rather than the total fungal concentration. These results may be useful in making recommendations as regards environmental control for fungal allergic patients.

Predictors of microbial agents in dust and respiratory health in the Ecrhs

Background

Dampness and mould exposure have been repeatedly associated with respiratory health. However, less is known about the specific agents provoking or arresting health effects in adult populations. We aimed to assess predictors of microbial agents in mattress dust throughout Europe and to investigate associations between microbial exposures, home characteristics and respiratory health.

Methods

Seven different fungal and bacterial parameters were assessed in mattress dust from 956 adult ECRHS II participants in addition to interview based home characteristics. Associations between microbial parameters and the asthma score and lung function were examined using mixed negative binomial regression and linear mixed models, respectively.

Results

Indoor dampness and pet keeping were significant predictors for higher microbial agent concentrations in mattress dust. Current mould and condensation in the bedroom were significantly associated with lung function decline and current mould at home was positively associated with the asthma score. Higher concentrations of muramic acid were associated with higher mean ratios of the asthma score (aMR 1.37, 95%CI 1.17-1.61). There was no evidence for any association between fungal and bacterial components and lung function.

Conclusion

Indoor dampness was associated with microbial levels in mattress dust which in turn was positively associated with asthma symptoms.

Electronic supplementary material

The online version of this article (doi:10.1186/s12890-015-0042-y) contains supplementary material, which is available to authorized users.

Indoor environmental exposures and exacerbation of asthma: an update to the 2000 review by the Institute of Medicine

BACKGROUND

Previous research has found relationships between specific indoor environmental exposures and exacerbation of asthma.

OBJECTIVES

In this review we provide an updated summary of knowledge from the scientific literature on indoor exposures and exacerbation of asthma.

METHODS

Peer-reviewed articles published from 2000 to 2013 on indoor exposures and exacerbation of asthma were identified through PubMed, from reference lists, and from authors' files. Articles that focused on modifiable indoor exposures in relation to frequency or severity of exacerbation of asthma were selected for review. Research findings were reviewed and summarized with consideration of the strength of the evidence.

RESULTS

Sixty-nine eligible articles were included. Major changed conclusions include a causal relationship with exacerbation for indoor dampness or dampness-related agents (in children); associations with exacerbation for dampness or dampness-related agents (in adults), endotoxin, and environmental tobacco smoke (in preschool children); and limited or suggestive evidence for association with exacerbation for indoor culturable Penicillium or total fungi, nitrogen dioxide, rodents (nonoccupational), feather/down pillows (protective relative to synthetic bedding), and (regardless of specific sensitization) dust mite, cockroach, dog, and dampness-related agents.

DISCUSSION

This review, incorporating evidence reported since 2000, increases the strength of evidence linking many indoor factors to the exacerbation of asthma. Conclusions should be considered provisional until all available evidence is examined more thoroughly.

CONCLUSION

Multiple indoor exposures, especially dampness-related agents, merit increased attention to prevent exacerbation of asthma, possibly even in nonsensitized individuals. Additional research to establish causality and evaluate interventions is needed for these and other indoor exposures.

Residential culturable fungi, (1-3, 1-6)-β-d-glucan, and ergosterol concentrations in dust are not associated with asthma, rhinitis, or eczema diagnoses in children

Qualitative reporting of home indoor moisture problems predicts respiratory diseases. However, causal agents underlying such qualitative markers remain unknown. In the homes of 198 multiple allergic case children and 202 controls in Sweden, we cultivated culturable fungi by directly plating dust, and quantified (1-3, 1-6)-β-D-glucan and ergosterol in dust samples from the child's bedroom. We examined the relationship between these fungal agents and degree of parent or inspector-reported home indoor dampness, and microbiological laboratory's mold index. We also compared the concentrations of these agents between multiple allergic cases and healthy controls, as well as IgE-sensitization among cases. The concentrations of culturable fungal agents were comparable between houses with parent and inspector-reported mold issues and those without. There were no differences in concentrations of the individual or the total summed culturable fungi, (1-3, 1-6)-β-D-glucan, and ergosterol between the controls and the multiple allergic case children, or individual diagnosis of asthma, rhinitis, or eczema. Culturable fungi, (1-3, 1-6)-β-D-glucan, and ergosterol in dust were not associated with qualitative markers of indoor dampness or mold or indoor humidity. Furthermore, these agents in dust samples were not associated with any health outcomes in the children.

Microbial secondary metabolites in school buildings inspected for moisture damage in Finland, The Netherlands and Spain

Secondary metabolites produced by fungi and bacteria are among the potential agents that contribute to adverse health effects observed in occupants of buildings affected by moisture damage, dampness and associated microbial growth. However, few attempts have been made to assess the occurrence of these compounds in relation to moisture damage and dampness in buildings. This study conducted in the context of the HITEA project (Health Effects of Indoor Pollutants: Integrating microbial, toxicological and epidemiological approaches) aimed at providing systematic information on the prevalence of microbial secondary metabolites in a large number of school buildings in three European countries, considering both buildings with and without moisture damage and/or dampness observations. In order to address the multitude and diversity of secondary metabolites a large number of more than 180 analytes was targeted in settled dust and surface swab samples using liquid chromatography/mass spectrometry (LC/MS) based methodology. While 42%, 58% and 44% of all samples collected in Spanish, Dutch and Finnish schools, respectively, were positive for at least one of the metabolites analyzed, frequency of detection for the individual microbial secondary metabolites - with the exceptions of emodin, certain enniatins and physcion - was low, typically in the range of and below 10% of positive samples. In total, 30 different fungal and bacterial secondary metabolites were found in the samples. Some differences in the metabolite profiles were observed between countries and between index and reference school buildings. A major finding in this study was that settled dust derived from moisture damaged, damp schools contained larger numbers of microbial secondary metabolites at higher levels compared to respective dust samples from schools not affected by moisture damage and dampness. This observation was true for schools in each of the three countries, but became statistically significant only when combining schools from all countries and thus increasing the sample number in the statistical analyses.

Exposure assessment of residential mould, fungi and microbial components in relation to children's health: achievements and challenges

Each day we are exposed to a complex mixture of microbial agents and components in indoor environments. A major part of this mixture derives from fungal and bacterial origin. The impact between those microbial agents in the home environment in relation to respiratory health in children is still a major issue in research. There is little known about the causal agents that provoke or arrest the development of allergic respiratory disorders in children. Identification is complicated by the biodiversity and variability of microbial components in indoor air as well as the lack of validated and standardized exposure assessment methods. In this review, we aim to consider all important aspects in terms of research which may encounter an epidemiological study. Apart from the need for standardized exposure assessment methods which consider cost, handling and effort, especially for the participants, we suggest that a combination of different analysis methods such as chemical and molecular methods may have the potential to best describe the microbial milieu in indoor environments at present. Further, the impact of mould and moisture remediation activities on health is still heavily under investigated, especially in larger prospective cohorts of children and should be a topic of future research. Moreover, the exposure to mould and microbial agents might be embedded in a broader spectrum of children's health such as behavior and cognitive development.

Meta-analysis of mould and dampness exposure on asthma and allergy in eight European birth cohorts: an ENRIECO initiative

BACKGROUND

Several cross-sectional studies during the past 10 years have observed an increased risk of allergic outcomes for children living in damp or mouldy environments.

OBJECTIVE

The objective of this study was to investigate whether reported mould or dampness exposure in early life is associated with the development of allergic disorders in children from eight European birth cohorts.

METHODS

We analysed data from 31 742 children from eight ongoing European birth cohorts. Exposure to mould and allergic health outcomes were assessed by parental questionnaires at different time points. Meta-analyses with fixed- and random-effect models were applied. The number of the studies included in each analysis varied based on the outcome data available for each cohort.

RESULTS

Exposure to visible mould and/or dampness during first 2 years of life was associated with an increased risk of developing asthma: there was a significant association with early asthma symptoms in meta-analyses of four cohorts [0-2 years: adjusted odds ratios (aOR), 1.39 (95% CI, 1.05-1.84)] and with asthma later in childhood in six cohorts [6-8 years: aOR, 1.09 (95% CI, 0.90-1.32) and 3-10 years: aOR, 1.10 (95% CI, 0.90-1.34)]. A statistically significant association was observed in six cohorts with symptoms of allergic rhinitis at school age [6-8 years: aOR, 1.12 (1.02-1.23)] and at any time point between 3 and 10 years [aOR, 1.18 (1.09-1.28)].

CONCLUSION

These findings suggest that a mouldy home environment in early life is associated with an increased risk of asthma particularly in young children and allergic rhinitis symptoms in school-age children.

Influence of home characteristics on airborne and dustborne endotoxin and β-D-glucan

The aim of this study was to assess the associations between airborne and dustborne microbial contaminants (endotoxin and β-D-glucan) and estimate the effects of home characteristics on exposure levels of these microbial contaminants. Endotoxin and β-D-glucan concentrations in airborne inhalable particles, airborne PM1 (<1 μm) and vacuumed dust from 184 residential homes were determined using specific Limulus amebocyte assays. Home characteristics were recorded by visual inspection and questionnaires. Linear regression and correlation analyses were performed. Inhalable endotoxin correlated with dust endotoxin (r = 0.34, p < 0.001) and PM1 endotoxin (r = 0.33, p < 0.001). Inhalable β-D-glucan correlated with dust β-D-glucan (r = 0.18, p < 0.01), but not with PM1 β-D-glucan. Significant correlation was also found between PM1 and dust concentrations for endotoxin (r = 0.26, p < 0.001), but not for β-D-glucan. Multivariate regression analyses showed only one significant association between airborne contaminants and environmental characteristics: inhalable β-D-glucan was positively associated with relative humidity with an effect size (change in the dependent variable corresponding to a unit increase in the independent variable) of 2.32 and p < 0.05. In contrast, several associations were found between dust concentrations and environmental characteristics. Dust endotoxin was positively associated with temperature (2.87, p < 0.01) and number of inhabitants (2.76, p < 0.01), whereas dust β-D-glucan was inversely associated with the presence of dogs (-2.24, p < 0.05) and carpet (-3.05, p < 0.01) in the home. In conclusion, dustborne contaminants were more strongly affected by home characteristics than airborne contaminants. Furthermore, even though statistically significant, the correlations between airborne and dustborne contaminants were weak. This indicates that airborne concentrations cannot be reliably predicted based on dustborne concentrations.

Visually observed mold and moldy odor versus quantitatively measured microbial exposure in homes

The main study objective was to compare different methods for assessing mold exposure in conjunction with an epidemiologic study on the development of children's asthma. Homes of 184 children were assessed for mold by visual observations and dust sampling at child's age 1 (Year 1). Similar assessment supplemented with air sampling was conducted in Year 7. Samples were analyzed for endotoxin, (1-3)-β-D-glucan, and fungal spores. The Mold Specific Quantitative Polymerase Chain Reaction assay was used to analyze 36 mold species in dust samples, and the Environmental Relative Moldiness Index (ERMI) was calculated. Homes were categorized based on three criteria: 1) visible mold damage, 2) moldy odor, and 3) ERMI. Even for homes where families had not moved, Year 7 endotoxin and (1-3)-β-d-glucan exposures were significantly higher than those in Year 1 (p<0.001), whereas no difference was seen for ERMI (p=0.78). Microbial concentrations were not consistently associated with visible mold damage categories, but were consistently higher in homes with moldy odor and in homes that had high ERMI. Low correlations between results in air and dust samples indicate different types or durations of potential microbial exposures from dust vs. air. Future analysis will indicate which, if any, of the assessment methods is associated with the development of asthma.

Otitis, rhinitis, and atopy in relation to domestic endotoxin and β-glucan exposure among children in Singapore

BACKGROUND

Exposure to microbial cell wall agents (MCWAs) has been related to the risk for atopy, otitis, and rhinitis.

OBJECTIVES

To relate domestic exposure to two important MCWAs-β-glucan and endotoxin-to the risk for otitis, rhinitis, atopy, and allergy in a sample of children from Singapore.

METHODS

Subjects (n = 98) were recruited from July 2006 to December 2008. Blood samples were taken to determine nonspecific IgE and skin prick tests were performed. Dust samples were collected from the bedrooms of the subjects and analyzed for the content of β-glucan and endotoxin, using the Limulus method.

RESULTS

Levels of IgE were significantly higher among children with rhinitis, and these children also had a larger proportion of atopics. There were no differences in β-glucan values between children with otitis, children with rhinitis, and controls. Endotoxin levels were lower in the homes of children with otitis, with a tendency for the levels to be lower in those with rhinitis. Among children with a high level of β-glucan, there was a higher proportion of those with high IgE values and atopy.

CONCLUSIONS

The results suggest that a low level of endotoxin is a risk factor for otitis and that a high level of β-glucan is a risk factor for atopic sensitisation. Reactions to domestic indoor exposure are determined by several indoor agents and their relative exposure levels.

Simultaneous determination of 186 fungal and bacterial metabolites in indoor matrices by liquid chromatography/tandem mass spectrometry

This paper describes the application of a previously published multi-mycotoxin method for food and feed matrices based on liquid chromatography/electrospray ionization-tandem mass spectrometry (HPLC/ESI-MS/MS) to the analysis of microbial metabolites in indoor matrices. The range of investigated analytes has been extended by 99 fungal and bacterial metabolites to cover now 186 compounds overall. The method is based on a single extraction step using an acidified acetonitrile/water mixture (which has been determined to be preferable to methanol and ethyl acetate) followed by analysis of the diluted crude extract. The analytical signal of one third of the investigated analytes was reduced by more than 50% due to matrix effects in a spiked extract of house dust, whereas the other investigated materials were less critical in that aspect. For determination of method performance characteristics, a spiked reference material for house dust was chosen as a model sample for an extremely complex matrix. With few exceptions, coefficients of variation of the whole procedure of <10% and limits of detection of <50 microg kg(-1) were obtained. The apparent recoveries were below 50% for half of the investigated analytes due to incomplete extraction and/or detection-related matrix effects. The application of the method to 14 samples from damp buildings revealed the presence of 20 different analytes at concentrations of up to 130 mg kg(-1). Most of these compounds have never been identified before in real-world samples, although they are known to be produced by indoor-relevant fungi. This underlines the great value of the described method for the on-site determination of microbial metabolites.

Confirmed moisture damage at home, respiratory symptoms and atopy in early life: a birth-cohort study

OBJECTIVES

Most previous studies on the association between moisture or mold problems in the home and respiratory symptoms in children were cross-sectional and based on self-reported exposure. The aim of this study was to evaluate the impact of objectively observed moisture damage and visible mold in the homes on early-life respiratory morbidity and atopic sensitization in a birth cohort.

METHODS

Building inspection was performed by building engineers in the homes of 396 children, and the children were followed up with questionnaires from birth to the age of 18 months. Specific immunoglobulin E levels were measured at the age of 1 year.

RESULTS

Doctor-diagnosed wheezing was associated with the severity of moisture damage in the kitchen and with visible mold in the main living area and especially in the bedroom of the child. The risk for parent-reported wheezing apart from cold increased with the severity of moisture damage in the kitchen. Moisture damage in the bathrooms or other interior spaces had no significant association with wheezing. No significant associations were observed for other end points, such as cough, or respiratory infections. There was a suggestion for an increased risk for sensitization to cat dander linked with moisture and mold exposure.

CONCLUSIONS

This birth-cohort study supports previous observations that moisture mold problems in the kitchen and in the main living area increase the risk for wheezing in early childhood. The results underline the importance of assessing separately the health effects of moisture and mold problems in different areas of the home.

Determination of volatile metabolites originating from mould growth on wall paper and synthetic media

Microbial volatile organic compounds (MVOCs) emitted from the mould species Penicillium expansum, P. chrysogenum, Aspergillus versicolor, A. fumigatus, A. niger and Cladosporium cladosporoides were analyzed by means of solid phase microextraction (SPME) and GCMS. The mould species were cultivated on the synthetic agar dichloran chloramphenicol (DG 18) and on wet wall paper. The production of MVOCs was monitored over several weeks to detect changes in the emission rates between the initial stage and later periods of growth. The cultivation on the synthetic agar resulted in MVOC patterns with a wide variety of signals. In contrast, the growth on wet wall paper led to changed MVOC patterns with less signals. The emission rates were drastically reduced. Components emitted by all six fungi species on wall paper were 2-pentanol and 2-pentanone. 1-Octen-3-ol was emitted by five fungi species. 2-Pentanol was only detected in considerable amounts during the first days of growth whereas 1-octen-3-ol had a more constant emission rate over the whole period of growth. On the basis of our studies some MVOCs could be proposed as specific for single fungi on wall paper, e.g. 1,3-dimethoxybenzene for A. versicolor and 2,4-pentandione for A. fumigatus.

Identification of spore allergens from the indoor mould Aspergillus versicolor

BACKGROUND

Indoor mould growth and dampness are associated with respiratory health effects and allergies and several studies demonstrated that mainly Aspergillus versicolor and Penicillium expansum are responsible for indoor mould exposure. In contrast, commercialized test systems to diagnose allergic reactions to this mould species are not available. In this study, allergenic proteins from spores of the indoor relevant species A. versicolor and P. expansum should get detected and identified.

METHODS

We used two-dimensional (2D)-gel electrophoresis of spore proteins and immunoblotting with sera from patients participating in an epidemiologic study about indoor exposure of moulds and their influence on the development of allergies (ESTERSPEGA). Sera were screened for IgE antibodies specific for proteins from A. versicolor, A. fumigatus and P. expansum in one-dimensional blots and in 2D immunoblots. From the 2D gels, the corresponding spots were picked and identified by mass spectrometry.

RESULTS

More than 20 allergens from A. versicolor were identified; in particular, seven major allergens were selected, which were detected by more than 90% of the positive sera. The most abundant allergen was glyceraldehyde-3-phosphate dehydrogenase, followed by an unnamed protein, which displays a high homology to sobitol/xylose reductase. The other allergens were identified as catalase A, hypothetical protein AN6918.2, enolase, hypothetical protein AN0297.2 and a protein with homology to a fungal malate dehydrogenase.

CONCLUSIONS

The results indicate an important role of spore proteins from A. versicolor for sensitization against indoor moulds and identification of the major allergens might enable species-specific diagnosis of allergic reactions.

Industrial air pollution and children's respiratory health: a natural experiment in Călăraşi

BACKGROUND

In 1993-1997, we described a high incidence of wheezing in children living near the iron, steel, and coke factory of Călăraşi (Romania). In 1998, the factory was closed.

OBJECTIVE

To investigate the influence of closing the factory on the incidence of wheezing in children living near the factory.

METHODS

We used this natural experiment to compare wheezing occurrence in children below age 2 in an area near the factory and in a village 10 km from the factory (Roseţi). We studied three birth cohorts: those 2 years old before the closing of the factory (group 1), those born before the closing and returning 2 after the closing (group 2), those born after the closing (group 3).

RESULTS

The relative risk (95% CI) of having at least one episode of wheezing during the first life-year was 0.51 (0.30-0.85) in group 3 versus group 1, and 0.95 (0.64-1.40) for group 2 versus group 1. After adjusting for possible confounders, the incidence dropped in Călăraşi (odds ratio [OR] 0.38, 95% CI 0.19-0.76), while it increased in Roseţi (OR 8.36, 95% CI 1.84-38.0). Results for the 2-year incidence were similar.

CONCLUSION

Industrial air pollution by the factory was the main risk factor for wheezing during the first life-years of the children of Călăraşi. Closing the factory resulted in a significant decrease in wheezing incidence rates, which still remained higher than in a nearby village.

Mass spectrometry-based strategy for direct detection and quantification of some mycotoxins produced by Stachybotrys and Aspergillus spp. in indoor environments

Dampness in buildings has been linked to adverse health effects, but the specific causative agents are unknown. Mycotoxins are secondary metabolites produced by molds and toxic to higher vertebrates. In this study, mass spectrometry was used to demonstrate the presence of mycotoxins predominantly produced by Aspergillus spp. and Stachybotrys spp. in buildings with either ongoing dampness or a history of water damage. Verrucarol and trichodermol, hydrolysis products of macrocyclic trichothecenes (including satratoxins), and trichodermin, predominately produced by Stachybotrys chartarum, were analyzed by gas chromatography-tandem mass spectrometry, whereas sterigmatocystin (mainly produced by Aspergillus versicolor), satratoxin G, and satratoxin H were analyzed by high-performance liquid chromatography-tandem mass spectrometry. These mycotoxin analytes were demonstrated in 45 of 62 building material samples studied, in three of eight settled dust samples, and in five of eight cultures of airborne dust samples. This is the first report on the use of tandem mass spectrometry for demonstrating mycotoxins in dust settled on surfaces above floor level in damp buildings. The direct detection of the highly toxic sterigmatocystin and macrocyclic trichothecene mycotoxins in indoor environments is important due to their potential health impacts.

Air pollution: a threat to the health of our children

BACKGROUND/METHODS

Current air pollution levels pose a threat to the health of children starting from conception. The scientific evidence is presented for mortality, morbidity, and sub-clinical effects. The first section deals with exposure data, the following sections with the evidence of health effects from epidemiology and toxicology leading to recommendations.

RESULTS

Improved air quality reduces the number of infants' deaths as well as disease and pain.

CONCLUSIONS

Medical doctors have a responsibility to know the facts and to advise their patients. Doctors when visiting their patients' homes should be aware of the possibly grave impact of the indoor environment for the respiratory health of their patients. They should recognize and advise the parents on problems associated with environmental tobacco smoke, poor ventilation, mould growth, and maintenance of heating installations. With regard to outdoor air pollution, doctors could serve as role models and also advise their patients and parents on environmentally friendly behaviour. Such behaviour not only calls for personal commitment but also for the right infrastructure to be provided (e.g. public transport, district heating). Doctors should be proactive in the community and in their country as advocates for a healthier environment for our children.

Cytotoxicity assessment of gliotoxin and penicillic acid in Tetrahymena pyriformis

Various studies have documented the associations between mold exposure and effects on health. Mycotoxins, which occur in spores and mold fragments, can be involved in processes that have pathological effects, such as adynamia of the immune system, recurrent infections of the respiratory tract, or asthma. Using Tetrahymena pyriformis, a single-cell organism well established as a suitable model for human respiratory epithelium-cell functionalities, we investigated dose-response relationships of the mycotoxins gliotoxin and penicillic acid. Our study focused on the viability (cell count, MTT assay), energy levels (adenosine-5'-triphosphate content), energy-providing processes (MTT reduction per cell), and cell respiration (oxygen consumption). Both mycotoxins acted as cytotoxins in a dose-dependent manner. Gliotoxin had a stronger inhibitory effect (EC50 0.38 microM) than did penicillic acid (EC50 343.19 microM). The energy-providing processes were not inhibited or were only weakly inhibited under the influence of gliotoxin, whereas penicillic acid caused stimulation of the physiological parameters. Summarizing the results, it is clear that the two investigated mycotoxins must have different modes of action. They are not only different in the strength of their toxic effects but also in a variety of physiological aspects. In addition, T. pyriformis showed differences in its ability to overcome the negative effects of particular mycotoxin exposures.

Immunoglobulin G Antibodies Against Environmental Moulds in a Norwegian Healthy Population Shows a Bimodal Distribution for Aspergillus versicolor

Immunoglobulin G (IgG) antibodies against moulds related to indoor dampness problems are used as biomarkers to indicate exposure. In the present study, we evaluated the frequency of mould exposure in an adult healthy population by examining levels of mould-specific IgG antibodies in Norwegian blood donors. Using enzyme-linked immunosorbent assay, 106 blood donor sera were analyzed for IgG antibodies to Aspergillus versicolor, Penicillium chrysogenum, Cladosporium herbarum, Stachybotrys chartarum and Fusarium oxysporum. The levels of specific IgG antibodies to P. chrysogenum, C. herbarum and S. chartarum correlated (r = 0.46-0.62). Responses to A. versicolor were considerably stronger than to the other moulds, and another 996 blood donor sera were analyzed for IgG antibodies to this mould. Women had significantly higher levels of specific IgG antibodies to A. versicolor than men. The concentration of A. versicolor-specific IgG antibodies showed a non-Gaussian, bimodal distribution profile, in which 12.5% were defined as positive to exposure. This suggests that significant mould exposure in a healthy population can be calculated from mean + 1SD. Western blotting analyses showed that antibody responses to A. versicolor were largely directed against carbohydrate antigens of unknown saccharides.

Do indoor pollutants and thermal conditions in schools influence student performance? A critical review of the literature

To assess whether school environments can adversely affect academic performance, we review scientific evidence relating indoor pollutants and thermal conditions, in schools or other indoor environments, to human performance or attendance. We critically review evidence for direct associations between these aspects of indoor environmental quality (IEQ) and performance or attendance. Secondarily, we summarize, without critique, evidence on indirect connections potentially linking IEQ to performance or attendance. Regarding direct associations, little strongly designed research was available. Persuasive evidence links higher indoor concentrations of NO(2) to reduced school attendance, and suggestive evidence links low ventilation rates to reduced performance. Regarding indirect associations, many studies link indoor dampness and microbiologic pollutants (primarily in homes) to asthma exacerbations and respiratory infections, which in turn have been related to reduced performance and attendance. Also, much evidence links poor IEQ (e.g. low ventilation rate, excess moisture, or formaldehyde) with adverse health effects in children and adults and documents dampness problems and inadequate ventilation as common in schools. Overall, evidence suggests that poor IEQ in schools is common and adversely influences the performance and attendance of students, primarily through health effects from indoor pollutants. Evidence is available to justify (i) immediate actions to assess and improve IEQ in schools and (ii) focused research to guide IEQ improvements in schools.

PRACTICAL IMPLICATIONS

There is more justification now for improving IEQ in schools to reduce health risks to students than to reduce performance or attendance risks. However, as IEQ-performance links are likely to operate largely through effects of IEQ on health, IEQ improvements that benefit the health of students are likely to have performance and attendance benefits as well. Immediate actions are warranted in schools to prevent dampness problems, inadequate ventilation, and excess indoor exposures to substances such as NO(2) and formaldehyde. Also, siting of new schools in areas with lower outdoor pollutant levels is preferable.

Spatiotemporal distribution of airborne mould spores in apartments

Indoor air contamination with mould spores currently experiences an increasing interest with respect to their relevance to health. To assess adverse health effects, epidemiological studies combine the health outcome of individuals with their concomitant exposure to airborne spores, which is observed, for example, during the current month. While the latter is representative for the studied period, health effects might also be the result of long term-exposure or emerge in consequence of a peak of pollution throughout the year. To consider such questions, additional information about the spatiotemporal distribution of airborne spores is necessary. This paper aims at elucidating the spatial and temporal variation of spore concentrations in Leipzig, Germany. The analysis is based on 1165 matched pairs of indoor and outdoor measurements taken in the period 1998-2002. All data were collected in the frame of previous epidemiological studies and refer to apartments. The analysis comprised spore concentrations (as CFU m(-3) in air) of the most important genera, such as Penicillium, Aspergillus, Alternaria, Mucorales, Cladosporium, and also for yeasts. We found two groups of fungi differing in their spatiotemporal distribution. As this behaviour can be explained by the predominant origin and growing conditions, we call them indoor-relevant and outdoor-relevant genera. Penicillium species are a representative of the former group, while the latter is well represented by Cladosporium. In the studied period we did not observe a clear trend in the spore concentration. Outdoors there is a year-to-year variation of Cladosporium spore concentrations, which follow the prevalent climatic conditions. For the spore concentration of the outdoor-relevant group a significant annual cycle was observed. Highest concentrations occurred during the summer months and were about 100 x the winter burden. That means, for a direct comparison of measurements of spore concentrations taken during different months the season has to be considered. We summarise the findings in a seasonal model, which is fitted to our measurements. Based on the model we developed a procedure for seasonal adjustment, which enabled us to estimate the annual peak spore concentration utilising one monthly observation.

Indoor fungi levels in homes of children with and without allergy history

A study was performed at the four sentinel health departments of Baden-Württemberg between November 1999 and March 2000 to investigate the indoor levels of fungi at the homes of school children (mean age 10 y) and to describe possible associations with allergy statuses. Three hundred and ninety-seven households of school children with (n = 199) and without (n = 198) allergic history were included in the study. The median of colony forming units (CFU/m3) of fungi, measured in the children's bedrooms' in indoor air, was 105 (range 5 to 15,000), in outdoor air 110 (range 10 to 1500). The median of viable mould spores (CFU/g dust) in floor dust was 28,500 (range 1500 to 1,235,000), in mattresses 16,250 (range 0 to 2,500,000). Neither climatological conditions, nor differences between urban and rural regions showed a systematic influence on fungi counts. There was no difference in concentrations and distribution of fungi species levels between children with and without allergic history. The sensitization rate against molds (IgE) was higher for children with allergic condition (9.2%) than in control children (4.4%), but there was no association with the fungi counts in the rooms. In conclusion, the study defined the mould levels in children's rooms, but did not find an association with allergic history of the children or their sensitization rate.