Toxigenic fungi in a water-damaged building: An intervention study

In an investigation of health complaints among employees of a water-damaged office building, the environment showed evidence of fungal contamination with the isolation of Stachybotrys chartarum in one of five bulk samples tested for fungal growth. In response, a public health official recommended that employees be relocated from the building. Employees were subsequently moved to a different environment. A focused environmental investigation of microbial growth within the building followed, revealing moderate to high levels of fungi (Penicillium, Aspergillus versicolor) and bacteria in bulk and surface samples. S. chartarum was identified in one of 19 (5%) environmental samples using Czapek agar. A health survey of building occupants revealed a high prevalence of multiple symptoms, with a predominance of neurobehavioral and upper respiratory tract complaints. The majority of symptoms were significantly less prevalent after relocation from the water-damaged environment. The initial hypothesis that exposure to toxigenic fungi was responsible for the high prevalence of reported symptoms is difficult to investigate and confirm given the current limits of epidemiological knowledge regarding exposure to these organisms and building-related illness. Future interventions where mycotoxin exposure is suspected should emphasize the importance of risk assessment and risk communication. Am. J. Ind. Med. 34:183–190, 1998. © 1998 Wiley-Liss, Inc.     

Assessment of environmental and surgical mask contamination at a student health center — 2012–2013 influenza season

Increased understanding of influenza transmission is critical for pandemic planning and selecting appropriate controls for healthcare personnel safety and health. The goals of this pilot study were to assess environmental contamination in different areas and at two time periods in the influenza season and to determine the feasibility of using surgical mask contamination to evaluate potential exposure to influenza virus. Bioaerosol samples were collected over 12 days (two 6-day sessions) at 12 locations within a student health center using portable two-stage bioaerosol samplers operating 8?hr each day. Surface samples were collected each morning and afternoon from common high-contact non-porous hard surfaces from rooms and locations where bioaerosol samplers were located. Surgical masks worn by participants while in contact with patients with influenza-like illness were collected. A questionnaire administered to each of the 12 participants at the end of each workday and another at the end of each workweek assessed influenza-like illness symptoms, estimated the number of influenza-like illness patient contacts, hand hygiene, and surgical mask usage. All samples were analyzed using qPCR. Over the 12 days of the study, three of the 127 (2.4%) bioaerosol samples, 2 of 483 (0.41%) surface samples, and 0 of 54 surgical masks were positive for influenza virus. For the duration of contact that occurred with an influenza patient on any of the 12 days, nurse practitioners and physicians reported contacts with influenza-like illness patients >60?min, medical assistants reported 15–44?min, and administrative staff reported <30?min. Given the limited number of bioaerosol and surface samples positive for influenza virus in the bioaerosol and surface samples, the absence of influenza virus on the surgical masks provides inconclusive evidence for the potential to use surgical masks to assess exposure to influenza viruses. Further studies are needed to determine feasibility of this approach in assessing healthcare personnel exposures. Information learned in this study can inform future field studies on influenza transmission.     

Culture-independent characterization of bacteria and fungi in a poultry bioaerosol using pyrosequencing: a new approach

Work in animal production facilities often results in exposure to organic dusts. Previous studies have documented decreases in pulmonary function and lung inflammation among workers exposed to organic dust in the poultry industry. Bacteria and fungi have been reported as components of the organic dust produced in poultry facilities. To date, little is known about the diversity and concentration of bacteria and fungi inside poultry buildings. All previous investigations have utilized culture-based methods for analysis that identify only biota cultured on selected media. The bacterial tag-encoded flexible (FLX) amplicon pyrosequencing (bTEFAP) and fungal tag-encoded flexible (FLX) amplicon pyrosequencing (fTEFAP) are modern and comprehensive approaches for determining biodiversity of microorganisms and have not previously been used to provide characterization of exposure to microorganisms in an occupational environment. This article illustrates the potential application of this novel technique in occupational exposure assessment as well as other settings. An 8-hr area sample was collected using an Institute of Medicine inhalable sampler attached to a mannequin in a poultry confinement building. The sample was analyzed using bTEFAP and fTEFAP. Of the bacteria and fungi detected, 116 and 39 genera were identified, respectively. Among bacteria, Staphylococcus cohnii was present in the highest proportion (23%). The total inhalable bacteria concentration was estimated to be 7503 cells/m3. Among the fungi identified, Sagenomella sclerotialis was present in the highest proportion (37%). Aspergillus ochraceus and Penicillium janthinellum were also present in high proportions. The total inhalable fungi concentration was estimated to be 1810 cells/m3. These estimates are lower than what has been reported by others using standard epifluorescence microscope methods. However, no study has used non-culture-based techniques, such as bTEFAP and fTEFAP, to evaluate bacteria and fungi in the inhalable fraction of a bioaerosol in a broiler production environment. Furthermore, the impact of this bTEFAP and fTEFAP technology has yet to be realized by the scientific community dedicated to evaluating occupational and environmental bioaerosol exposure.     

Health and immunologv study following exposure to toxigenic fungi (Stachybotrys chartarum) in a water-damaged office environment

 There is growing concern about adverse health effects of fungal bio-aerosols on occupants of water-damaged buildings. Accidental, occupational exposure in a nonagricultural setting has not been investigated using modern immunological laboratory tests. The objective of this study was to evaluate the health status of office workers after exposure to fungal bio-aerosols, especially Stachybotrys chartarum (atra) (S. chartarum) and its toxigenic metabolites (satratoxins), and to study laboratory parameters or biomarkers related to allergic or toxic human health effects. Exposure characterization and quantification were performed using microscopic, culture, and chemical techniques. The study population (n=53) consisted of 39 female and 14 male employees (mean age 34.8 years) who had worked for a mean of 3.1 years at a problem office site; a control group comprised 21 persons (mean age 37.5 years) without contact with the problem office site. Health complaints were surveyed with a 187-item standardized questionnaire. A comprehensive test battery was used to study the red and white blood cell system, serum chemistry, immunology/antibodies, lymphocyte enumeration and function. Widespread fungal contamination of water-damaged, primarily cellulose material with S. chartarum was found. S. chartarum produced a macrocyclic trichothecene, satratoxin H, and spirocyclic lactones. Strong associations with exposure indicators and significant differences between employees (n=53) and controls (n=21) were found for lower respiratory system symptoms, dermatological symptoms, eye symptoms, constitutional symptoms, chronic fatigue symptoms and several enumeration and function laboratory tests, mainly of the white blood cell system. The proportion of mature T-lymphocyte cells (CD3%) was lower in employees than in controls, and regression analyses showed significantly lower CD3% among those reporting a history of upper respiratory infections. Specific S. chartarum antibody tests (IgE and IgG) showed small differences (NS). It is concluded that prolonged and intense exposure to toxigenic S. chartarum and other atypical fungi was associated with reported disorders of the respiratory and central nervous systems, reported disorders of the mucous membranes and a few parameters pertaining to the cellular and humoral immune system, suggesting a possible immune competency dysfunction. Received: 3 May 1995/Accepted: 17 October 1995     

Hydrophilic fungi and ergosterol associated with respiratory illness in a water-damaged building

BACKGROUND: Damp building-related respiratory illnesses are an important public health issue. OBJECTIVE: We compared three respiratory case groups defined by questionnaire responses [200 respiratory cases, 123 of the respiratory cases who met the epidemiologic asthma definition, and 49 of the epidemiologic asthma cases who had current physician-diagnosed asthma with post-occupancy onset] to a comparison group of 152 asymptomatic employees in an office building with a history of water damage. METHODS: We analyzed dust samples collected from floors and chairs of 323 cases and comparisons for culturable fungi, ergosterol, endotoxin, and cat and dog allergens. We examined associations of total fungi, hydrophilic fungi (requiring water activity > or = 0.9), and ergosterol with the health outcomes using logistic regression models. RESULTS: In models adjusted for demographics, respiratory illnesses showed significant linear exposure-response relationships to total culturable fungi [interquartile range odds ratios (IQR-OR) = 1.37-1.72], hydrophilic fungi (IQR-OR = 1.45-2.19), and ergosterol (IQR-OR = 1.54-1.60) in floor and chair dusts. Of three outcomes analyzed, current asthma with postoccupancy physician diagnosis was most strongly associated with exposure to hydrophilic fungi in models adjusted for ergosterol, endotoxin, and demographics (IQR-OR = 2.09 for floor and 1.79 for chair dusts). Ergosterol levels in floor dust were significantly associated with epidemiologic asthma independent of culturable fungi (IQR-OR = 1.54-1.55). CONCLUSIONS: Our findings extend the 2004 conclusions of the Institute of Medicine [Human health effects associated with damp indoor environments. In: Damp Indoor Spaces and Health. Washington DC:National Academies Press, 183-269] by showing that mold levels in dust were associated with new-onset asthma in this damp indoor environment. Hydrophilic fungi and ergosterol as measures of fungal biomass may have promise as markers of risk of building-related respiratory diseases in damp indoor environments.     

Hatchery workers’ IgG antibody profiles to airborne bacteria

Occupational exposure to high concentrations of airborne bacteria in poultry production is related to an increased risk of respiratory disorders. However, etiology and in particular microorganisms’ potential role in pathogenesis still needs to be elucidated. Thus, detection of specific antibodies against occupational microbial antigens may lead to identification of potentially harmful species. For the purpose of IgG titer determination, indirect immunofluorescence on various bacterial isolates from duck hatchery air was combined with image-based quantification of fluorescence intensity. Moreover, in addition to established assays with pure bacterial cultures, a new approach utilized complex bioaerosol samples for detection of anti-microbial antibodies in human sera by determination of percentages of antibody-bound cells in different serum dilutions. Mean titers in sera from hatchery workers and a non-exposed control group did not display significant differences for most tested isolates and application of comprehensive cluster analysis to entire titer data revealed no structure reflecting workers and controls group. Furthermore, determination of immunoreactivity to the complete microbial community in workplace air displayed similar proportions of antibody-bound cells in both groups. Although no general differences in immunoreaction patterns were observed, mean titers to a Proteus mirabilis isolate and to 3 of 4 distinct Acinetobacter baumannii isolates were higher in the group of hatchery workers than in the reference group indicating a potential applicability as exposure markers. We conclude, despite long term bioaerosol exposure, hatchery workers’ IgG antibody profiles to tested antigens did not differ substantially from those of the control group. However, increased workers’ titers to A. baumannii and clinical relevance of this species should lead to further investigations regarding potential involvement in pathogenesis of occupational respiratory disorders.     

Effects of bioaerosol exposure on work-related symptoms among Swiss sawmill workers

Objective Exposure to bioaerosols in the occupational environment of sawmills could be associated with a wide range of health effects, in particular respiratory impairment, allergy and organic dust toxic syndrome. The objective of the study was to assess the frequency of medical respiratory and general symptoms and their relation to bioaerosol exposure. Method Twelve sawmills in the French part of Switzerland were investigated and the relationship between levels of bioaerosols (wood dust, airborne bacteria, airborne fungi and endotoxins), medical symptoms and impaired lung function was explored. A health questionnaire was distributed to 111 sawmill workers. Results The concentration of airborne fungi exceeded the limit recommended by the Swiss National Insurance (SUVA) in the twelve sawmills. This elevated fungi level significantly influenced the occurrence of bronchial syndrome (defined by cough and expectorations). No other health effects (irritations or respiratory effects) could be associated to the measured exposures. We observed that junior workers showed significantly more irritation syndrome (defined by itching/running nose, snoring and itching/red eyes) than senior workers. Lung function tests were not influenced by bioaerosol levels nor dust exposure levels. Conclusion Results suggest that occupational exposure to wood dust in a Swiss sawmill does not promote a clinically relevant decline in lung function. However, the occurrence of bronchial syndrome is strongly influenced by airborne fungi levels.     

Acute respiratory effects in the potato processing industry due to a bioaerosol exposure.

The relation between bioaerosol exposure in the potato starch industry and work related respiratory symptoms is described. One group of workers was exposed to high dust concentrations (geometric mean up to 56.0 mg/m3) with low endotoxin and antigen concentrations (geometric mean up to 12.6 ng/m3 and 90 relative antigen units (RAU) per m3). A second group was exposed to low dust concentrations (geometric mean up to 3.9 mg/m3), but the endotoxin and antigen concentrations were high (geometric means of environmental samples up to 72 ng/m3 and 2.9.10(2)RAU/m3). Twenty of the 48 workers had specific IgG4 titres to dust extract. Of these 20 workers, 14 showed an increase in IgG4 titre during the first month of the potato processing season. No specific IgE antibodies to dust extracts were found. Twenty two workers were equipped with a Mini-Wright peak flow meter during a four week period. Two workers showed a work related decline in peak flow values. It was concluded that exposure to dust made airborne during the refining process of potato starch may cause work related respiratory symptoms.     

Health effects of indoor fungal bioaerosol exposure

Occupational and environmental health professionals are confronted with issues concerning the health effects of indoor fungal bioaerosol exposure. This article reviews current data on the health effects of indoor mold exposure and provides practical suggestions for occupational and environmental health practitioners regarding how best to manage these exposures based on published human studies. We conducted MEDLINE searches and reviewed all English language studies on indoor mold exposure (visible survey or objective sampling) and human health effects published from 1966 to November 2002. The main findings of the studies are analyzed in conjunction with plausible association of health effects and fungal exposure. Five case control studies, 17 cross-sectional surveys, and 7 case reports met the selection criteria. Current evidence suggests that excessive moisture promotes mold growth and is associated with an increased prevalence of symptoms due to irritation, allergy, and infection. However, specific human toxicity due to inhaled fungal toxins has not been scientifically established. Methods for measuring indoor bioaerosol exposure and health assessment are not well standardized, making interpretation of existing data difficult. Additional studies are needed to document human exposure-disease and dose-response relationships.     

Antibodies against molds and mycotoxins following exposure to toxigenic fungi in a water-damaged building

Exposure to molds in water-damaged buildings can cause allergy, asthma, hypersensitivity pneumonitis, mucus membrane irritation, and toxicity--alone or in combination. Despite this, significant emphasis has been placed only on Type I allergy and asthma, but not on the other 3 types of allergies. In this study, we sought to evaluate simultaneous measurements of immunoglobulin (Ig) G, IgM, IgA, and IgE antibodies against the most common molds, and their mycotoxins, cultured from water-damaged buildings. Antibodies against 7 different molds and 2 mycotoxins were determined by enzyme-linked immunosorbent assay (ELISA) in the blood of 40 controls and 40 mold-exposed patients. The IgG antibody levels against all 7 of the molds used, as well as the 2 mycotoxins, were significantly greater in patients than in controls. The IgM antibody levels were significantly different in patients for only 6 of 9 determinations. Regarding IgA determinations, antibodies were elevated significantly against all antigens tested, except Epicoccum. However, the differences in IgE levels in controls and mold-exposed patients were significant only for Aspergillus and satratoxin. These differences implied that, overall, the healthy control group was different from the mold-exposed patients for IgG, IgM, and IgA antibodies, but not for the IgE anti-mold antibody. Most patients with high levels of antibodies against various mold antigens also exhibited elevated antibodies against purified mycotoxins, indicating that the patients had been exposed to mold spores and mycotoxins. Detection of high levels (colony-forming units per cubic meter) of molds--which, in this study, strongly suggested that there existed a reservoir of spores in the building at the time of sampling--along with a significant elevation in IgG, IgM, or IgA antibodies against molds and mycotoxins, could be used in future epidemiologic investigations of fungal exposure. In addition to IgE, measurements of IgG, IgM, and IgA antibodies should be considered in mold-exposed individuals.     

Resolution of sick building syndrome in a high-security facility

The main objective of this article is to serve as a case study for other industrial hygiene (IH) professionals' review as a "real world" effort in responding to a facility perceived as "sick" by its occupants. As many industrial hygienists do not have extensive backgrounds in evaluating microbial air contaminants or the mechanical function of building HVAC units, the overall intent is to provide "lessons learned" to IH generalists who may be asked to participate in indoor environmental quality (IEQ) surveys. In September 1994, a suspected case of "sick building syndrome" was investigated (with significant airborne fungal loads confirmed) at a communications center after numerous occupants reported upper respiratory disease and/or allergy-type symptoms. The setting was a two-story structure approximately 30 years old, with a normal occupancy load of 350 to 400 persons. In addition to continual structural modifications, the central HVAC air conditioning systems had poor maintenance histories. Inspection of HVAC components revealed visible fungal growth on air filters and air ducts and in cooling fan condensate drip pans. Fungal air samples were collected with an Anderson N6 air sampler and Sabouraund dextrose agar media. Over a study period of 23 months, three rounds of 26 air samples were collected for 5 minutes each at 28.3 liters/minute airflow. Cultures exhibited fungi such as Aspergillus, Penicillium, Alternaria, and Cladosporium. Certain strains of these fungi produce mycotoxins that may cause a variety of deleterious health effects such as those described by occupants. Initial 1994 airborne fungal concentrations ranged from 85 to 6157 colony forming units (CFUs) per cubic meter of sampled air (CFU/m3). Some investigators have reported fungal concentrations as low as 245 CFU/m3 associated with complaint sites in other buildings. Remediation efforts involved hiring a dedicated mechanic to implement a HVAC preventive maintenance program (including regular replacement of all HVAC air filters and cleaning of accessible components with water/bleach solution). Post-abatement January 1996 re-sampling revealed a significant drop in airborne fungal colonies up to 97 percent (range = 21 to 1092 CFUs/m3)--which also coincided with physicians at the local hospital sensing a qualitative reduction in patient visits from facility workers. To address seasonal bias, a final August 1996 air sample round revealed a range of 14 to 500 CFUs/m3. Of the 21 workspaces sampled in all three rounds, nine continued to show a decline in CFUs/m3 from September 1994 baseline counts. These results demonstrate the critical role of an ongoing HVAC maintenance program for reducing potential reservoirs of fungal organisms in indoor work environments. Building renovations (especially those involving major changes to building layout and usage) can adversely affect IEQ if plans do not include coordinated updates and regular preventive maintenance of HVAC systems. Eventual negative outcomes can be reduced occupant productivity and deleterious health effects.     

Exposure to airborne fungi, MVOC and mycotoxins in biowaste-handling facilities

Health impacts due to fungi in indoor air can only be estimated reliably, if both fungal propagules and fungal secondary metabolites are qualified and quantified. In the present study, the fungal species composition in a compost facility is compared to the spectrum of microbial metabolites in the air with regard to the physiological properties of different fungal species. A number of relevant fungi was tested for the production of both volatile and non-volatile metabolites on different substrata. The profiles of mycotoxins and microbial volatile organic compounds (MVOC) turned out to be specific for certain species in pure culture. Consequently, the fungi may have different toxicological health impacts, though information on the relevance of microbial volatiles is still limited.     

An environmental and respiratory health survey of workers in a grain mill in the Johannesburg area,South Africa

A respiratory health survey was conducted in a grain mill and the relationship of health indicators to quantitative measures of airborne dust, fungal, and bacterial contamination was examined. Respiratory symptoms were more prevalent in the high dust exposure categories; lung function levels were also higher in the high dust exposure categories, consistent with a “healthy” worker effect. Workers in the three higher dust exposure categories showed either no change or a decrease in lung function over the working week, while workers in the low exposure category demonstrated an improvement in lung function over the working week. Total dust and microbiological (fungal and bacterial) load were found to be significantly related to each other, and the relationship of microbiological load to lung function level and changes over the working week were similar to those found for total dust © 1993 Wiley-Liss, Inc.     

Allergic respiratory disease and fungal remediation in a building in a subtropical climate

An outbreak of allergic respiratory disease occurred in a new building that was characterized from initial occupancy by the presence of extensive visible mold (especially Aspergillus versicolor) on interior surfaces. Epidemiological study of the occupants of both the affected building and a comparison neighboring structure indicated high rates of respiratory and other symptoms among persons working in the affected building. Subsequent clinical evaluations of some persons occupying the building for up to five years identified several cases of building-related allergic respiratory disease, including asthma and hypersensitivity pneumonitis. Based on these findings, the building was evacuated before remediation began. The mycological goal of the three-year building restoration project was to reduce concentration of non-phylloplane fungi such as A. versicolor to the lowest feasible level. All visibly colonized materials in the building were discarded and all fine dust on interior surfaces was removed by vacuuming and/or damp wiping. A medical surveillance program utilizing serial self-reported questionnaires and readily available clinical evaluations was designed to monitor the health of building occupants after re-entry. Symptom rates just prior to building reentry were substantially lower than those found before evacuation and have remained unchanged after re-occupancy was completed. No new or recrudescent cases of illness are known to have occurred after building re-entry.     

Endemic work-related febrile respiratory illness among construction workers

Construction workers building Denver International Airport (DIA) reported work-related respiratory and flulike symptoms of several months duration. We performed a cross-sectional interview study of 495 randomly selected DIA workers from six contractors in comparison with preplacement workers. We defined cases as workers with two work-attributed lower respiratory symptoms and one work-attributed systemic symptom. Case rates were significantly higher among DIA workers (34%) compared with those who had never worked at DIA (2%). Risk factors for illness included exposure to fireproofing (OR, 4.21; 95% CI, 1.95–9.08), work in tunnels and adjoining areas (OR, 3.07; 95% CI, 1.84–5.12), length of DIA employment (OR, 0.65; 95% CI, 0.46–0.92), and preexisting bronchitis (OR, 2.43; 95% CI, 1.17–5.05). Our industrial hygiene investigation revealed alkaline dust (pH 11) present at a worksite associated with elevated risk of illness, and we identified airborne Penicillium mold widely distributed indoors at DIA. Clinical evaluation of 26 self-identified symptomatic DIA employees, including bronchoalveolar lavage and biopsy in 10, revealed work-related asthma in three workers and histologic evidence of chronic bronehitis in four who had never smoked. We concluded that future investigations of endemic work-related febrile respiratory illness among construction workers should evaluate its association with indoor exposure to dusts from alkaline fireproofing, Penicillium mold, mycotoxins, and bacterial bioaerosols.     

Populations and determinants of airborne fungi in large office buildings

Bioaerosol concentrations in office environments and their roles in causing building-related symptoms have drawn much attention in recent years. Most bioaerosol studies have been cross-sectional. We conducted a longitudinal study to examine the characteristics of airborne fungal populations and correlations with other environmental parameters in office environments. We investigated four office buildings in Boston, Massachusetts, during 1 year beginning May 1997, recruiting 21 offices with open workstations. We conducted intensive bioaerosol sampling every 6 weeks resulting in 10 sets of measurement events at each workstation, and recorded relative humidity, temperature, and CO2 concentrations continuously. We used principal component analysis (PCA) to identify groups of culturable fungal taxa that covaried in air. Four major groupings (PCA factors) were derived where the fungal taxa in the same groupings shared similar ecological requirements. Total airborne fungal concentrations varied significantly by season (highest in summer, lowest in winter) and were positively correlated with relative humidity and negatively related to CO2 concentrations. The first and second PCA factors had similar correlations with environmental variables compared with total fungi. The results of this study provide essential information on the variability within airborne fungal populations in office environments over time. These data also provide background against which cross-sectional data can be compared to facilitate interpretation. More studies are needed to correlate airborne fungi and occupants' health, controlling for seasonal effects and other important environmental factors.     

A systematic review of the public health risks of bioaerosols from intensive farming

Background

Population growth, increasing food demands, and economic efficiency have been major driving forces behind farming intensification over recent decades. However, biological emissions (bioaerosols) from intensified livestock farming may have the potential to impact human health. Bioaerosols from intensive livestock farming have been reported to cause symptoms and/or illnesses in occupational-settings and there is concern about the potential health effects on people who live near the intensive farms. As well as adverse health effects, some potential beneficial effects have been attributed to farm exposures in early life. The aim of the study was to undertake a systematic review to evaluate potential for adverse health outcomes in populations living near intensive livestock farms.

Contaminated commercial charcoal as a source of fungi in the respiratory tract.

OBJECTIVE: To investigate the possibility that contaminated commercial activated charcoal may serve as a source for fungal colonization or infection of the lower respiratory tract. DESIGN: The clinical course of a patient who aspirated commercial activated charcoal was reviewed. Fungal cultures were performed for 2 samples of an activated charcoal in sorbitol product from separate lots produced by a single manufacturer. Details of the manufacturing process were obtained from a representative of the manufacturer. SETTING: An intensive care unit in a large community teaching hospital. PATIENTS: A single patient with steroid-treated lung disease who developed a fatal pulmonary illness after aspirating a commercial activated charcoal product. RESULTS: After aspirating the charcoal product, the patient developed respiratory tract colonization and possible infection with Aspergillus niger, Paecilomyces variotii, and Penicillium species. Similar fungal species were isolated from cultures of samples obtained from two separate lots of the same commercial activated charcoal product. Several opportunities for contamination during the manufacturing process were identified. CONCLUSIONS: Physicians caring for immunocompromised patients should be aware that commercial activated charcoal products can be a source of fungal respiratory tract colonization that may mimic or cause pneumonia.     

Assessment of exposure to organic dust in a hemp processing plant

The aim of this preliminary study was to assess exposure to various constituents of the organic dust generated during the processing of hemp in a small group of exposed workers. Airborne levels of inhalable dust, endotoxin and soluble protein, and the respirable, thoracic and inhalable fractions of fungal, bacterial and actinomycete contamination were measured in the personal breathing zone of exposed workers. Inhalable dust, endotoxin, fungal and bacterial contamination all exceeded levels found in similar vegetable fibre processing factories, since inhalable dust levels ranged from 10.4 to 79.8 mg/m(3) and inhalable bacterial levels between 4.7 and 190 x 10(6) cfu/m(3). Soluble protein and endotoxin (r=0.99, P<0.0001), endotoxin and inhalable dust (r=0.94, P<0.005) and inhalable dust and protein (r=0.98, P<0.0001) were significantly correlated, suggesting that there was little variation in the composition of the dust from different sites or activities around the workplace. Andersen sampling gave an indication of background microbe levels, although no attempt was made to identify the specific microorganisms as all plates were significantly overgrown. Airborne assessments demonstrated that exposures were highly task specific. For example, sweeping the floor generated the highest exposure levels of total dust, protein, endotoxin, bacteria and fungi. Therefore, we have shown that a modern-day hemp fibre processing plant produces significant quantities of respirable dust which is highly contaminated with endotoxin and microorganisms. This organic dust has the potential to cause a range of ill health problems.     

Evaluation and a predictive model of airborne fungal concentrations in school classrooms

Exposure to airborne fungal products may be associated with health effects ranging from non-specific irritation of the respiratory tract or mucus membranes to inflammation provoked by specific fungal antigens. While concentrations of airborne fungi are frequently measured in indoor air quality investigations, the significance of these measurements in the absence of visual mold colonization is unclear. This study was undertaken to evaluate concentrations of airborne fungal concentrations in school classrooms within a defined geographic location in British Columbia, Canada, and to build a model to clarify determinants of airborne fungal concentration. All elementary schools within one school district participated in the study. Classrooms examined varied by age, construction and presence or absence of mechanical ventilation. Airborne fungal propagules were collected inside classrooms and outdoors. Variables describing characteristics of the environment, buildings and occupants were measured and used to construct a predictive model of fungal concentration. The classrooms studied were not visibly contaminated by fungal growth. The data were evaluated using available guidelines. However, the published guidelines did not take into account significant aspects of the local environment. For example, there was a statistically significant effect of season on the fungal concentrations and on the proportional representation of fungal genera. Rooms ventilated by mechanical means had significantly lower geometric mean concentrations than naturally ventilated rooms. Environmental (temperature, outdoor fungal concentration), building (age) and ventilation variables accounted for 58% of the variation in the measured fungal concentrations. A methodology is proposed for the evaluation of airborne fungal concentration data which takes into account local environmental conditions as an aid in the evaluation of fungal bioaerosols in public buildings.