Biomedical subjects

A Nevalainen

Publications and source records attributed to A Nevalainen.

At least 19 recordsLinked to original sources

PubMed2006

Moisture damage and childhood asthma: a population-based incident case-control study.

Most previous studies on the association between moisture damage and asthma have been cross-sectional and relied on self-reported exposure and health. The present authors studied the association by carrying out careful home inspections among new, clinically determined cases of asthma and controls. New cases of asthma aged 12-84 months (n = 121) were recruited prospectively and matched for year of birth, sex and living area with two randomly selected population controls (n = 241). Trained engineers visited all homes. Both cases and controls had lived >or=75% of their lifetime or the past 2 yrs in their current home. Risk of asthma increased with severity of moisture damage and presence of visible mould in the main living quarters but not in other areas of the house. Cases more often had damage in their bedroom. Associations were comparable for atopic and nonatopic asthma and for children aged >30 months or <or=30 months. The present results, using standardised assessment of exposure and asthma, suggest that moisture damage and mould growth in the main living quarters are associated with the development of asthma in early childhood.

Air Pollution, Indoor↗

PubMed2006

Dust sampling methods for endotoxin - an essential, but underestimated issue.

Exposure to farming environment in early life has been associated with lower risk for allergic diseases possibly caused by increased exposure to endotoxin. The aims of this study were to compare the reproducibility of different sampling methods for endotoxin, and to determine whether environmental characteristics have different effect on endotoxin levels of different sample types. The reproducibility of sampling methods (bed dust, floor dust, vacuum cleaner dust bag dust, settled dust and air samples) was studied with repeated sampling (five visits during 1 year) in five farming and five urban homes. To examine determinants of endotoxin for different types of dust sample, sampling was conducted once in 12 farming and 17 urban homes. Endotoxin was analyzed using Limulus Amebocyte Lysate assay. Bed dust samples had the best reproducibility (intraclass correlation, ICC=66%), but the difference between farming and non-farming homes was not clear with this sample type. The reproducibility of floor (ICC=52%) and settled dust (ICC=51%) was moderate. With these sample types the difference between farming and non-farming homes was clear. Settled dust had some seasonal variation. Based on this study, the best compromise for sampling for endotoxin appears to be floor dust sample followed by bed and settled dust samples. Practical Implications Endotoxins have been widely measured, even though the validity of different sample types to reflect the endotoxin exposure level of an indoor environment is poorly known. This study shows that bed dust samples have the best reproducibility, but they do not reflect the differences in exposure due to environmental factors such as farming. Floor dust samples with moderate reproducibility may be the best choice for sampling of endotoxin in large field studies.

Air Pollution, Indoor↗

PubMed2006

Children's homes--determinants of moisture damage and asthma in Finnish residences.

UNLABELLED: Certain housing characteristics increase the risk for moisture damage, which has been associated with increased risk for asthma in children. Modeling moisture damage as a function of these characteristics could therefore provide a simple tool to estimate building-related risk for asthma. This study aimed to find out specific associations between asthma case-control status of children and moisture damage and housing characteristics. The data consisted of information on 121 asthmatic children and predominately two age-, gender- and place of residence-matched control children for every case, and information on moisture damage and housing characteristics in the homes of the children. In a previous study, we found a statistically significant association between moisture damage observations in main living areas and asthma in children. Using logistic regression, five models were formulated to predict moisture damage status of the homes and moisture damage status of living areas. The models were able to classify the damage status correctly in 65.0-87.7% of the homes (kappa values 0.10-0.47) as functions of housing characteristics. None of the models qualified as a significant determinant of the case-control status of the children. PRACTICAL IMPLICATIONS: It can be hypothesized that building-related risk for asthma could be roughly estimated using models predicting moisture damage status of buildings as a function of easily obtainable housing characteristics. The results of this study indicated that, with a moderate certainty, it is possible to model moisture damage status of buildings using housing characteristics. However, the models developed did not associate with asthma in children. In conclusion, it was not possible to estimate the risk for asthma by studying housing characteristics only, but detailed information on moisture damage (e.g. location of damage) was crucial for such estimation.

Air Pollution, Indoor↗

PubMed2006

A preliminary study on the association between ventilation rates in classrooms and student performance.

Poor conditions leading to substandard indoor air quality (IAQ) in classrooms have been frequently cited in the literature over the past two decades. However, there is limited data linking poor IAQ in the classrooms to student performance. Whereas, it is assumed that poor IAQ results in reduced attendance and learning potential, and subsequent poor student performance, validating this hypothesis presents a challenge in today's school environment. This study explores the association between student performance on standardized aptitude tests that are administered to students on a yearly basis, to classroom carbon dioxide (CO2) concentrations, which provide a surrogate of ventilation being provided to each room. Data on classroom CO2 concentrations (over a 4-5 h time span within a typical school day) were recorded in fifth grade classrooms in 54 elementary schools within a school district in the USA. Results from this preliminary study yield a significant (P < 0.10) association between classroom-level ventilation rate and test results in math. They also indicate that non-linear effects may need to be considered for better representation of the association. A larger sample size is required in order to draw more definitive conclusions. Practical Implications Future studies could focus on (1) gathering more evidence on the possible association between classroom ventilation rates and students' academic performance; (2) the linear/non-linear nature of the association; and (3) whether it is possible to detect 'no observed adverse effect level' for adequate ventilation with respect to academic performance in schools. All of this information could be used to improve guidance and take regulatory actions to ensure adequate ventilation in schools. The high prevalence of low ventilation rates, combined with the growing evidence of the positive impact that sufficient ventilation has on human performance, suggests an opportunity for improving design and management of school facilities.

Air Pollution, Indoor↗

PubMed2005

pH effects on 10 Streptomyces spp. growth and sporulation depend on nutrients.

AIMS: Streptomycetes are regarded to prefer neutral to alkaline environmental pH, although they commonly occur at remarkably variable pH and nutritional conditions. Therefore, the dependence of 10 Streptomyces spp. pH tolerance on nutrients was determined. METHODS AND RESULTS: Ten environmental Streptomyces spp. were grown and sporulated between pH 4.0 and 11.5, at the interval of 1.5, on starch-casein-KNO(3), tryptone-yeast extract-glucose, glycerol-arginine and tryptone-soy agars, and three their modifications. On media with starch and casein; glucose, tryptone and yeast extract; tryptone and soy peptone; and glycerol-arginine and yeast extract strains grew over a broad pH range between 4.0-5.5 and 10.0-11.5. On glycerol-arginine and on medium with Na-propionate, NH(4)NO(3) and yeast extract, streptomycetes grew optimally at pH 7.0 and above. The high organic load enabled the growth over a wide pH range. The sporulation pH ranges followed those for growth. CONCLUSIONS: The high organic load enabled the growth over a wide pH range. The strain-specific differences in sporulation were greater than those caused by pH. The best medium for sporulation contained glucose and tryptone with minerals of glycerol-arginine agar at pH 5.5. SIGNIFICANCE AND IMPACT OF THE STUDY: The growth pH ranges, pH ranges for the optimal growth, and sporulation were strongly dependent on nutrients.

Agar↗

PubMed2005

Of microbes and men.

UNLABELLED: Moisture accumulation in building structures, the microbial ecology of water-damaged sites and human exposure to biological contaminants are complex phenomena and may result in various types of indoor air pollution and adverse health outcomes. Commonly reported are building-related irritation symptoms, respiratory infections and non-specific symptoms and occasionally neurological impairment. Various diseases have been associated with mold exposure, e.g. an increased risk of asthma development and exacerbation as well as clusters of hypersensitivity pneumonitis, pulmonary hemorrhage in infants and rheumatic diseases. The causal agents of these illnesses, still poorly understood, may be linked to the complex interactions between bacteria and fungi with environmental growth substrates and other microorganisms which lead to a wide diversity of exposures. Fungi and bacteria growing on building materials may produce toxic secondary metabolites, and the material appears to be a key determinant of metabolite production. Modern building technology has provided new ecological niches for microbes which readily exploit faults in moisture control. To better describe microbial exposures in buildings, current method development focuses on chemical markers of biomass and assays for specific genetic sequences. PRACTICAL IMPLICATIONS: Dampness and moisture phenomena in buildings, resulting microbial and chemical exposures and individual human responses are complex phenomena. While the causative links between exposing agents and health responses are still not well understood, the essential issue is to prevent the problems with good design, construction and maintenance.

Air Microbiology↗

PubMed2005

Effects of moisture-damage repairs on microbial exposure and symptoms in schoolchildren.

UNLABELLED: Effects of renovation on symptom prevalence and microbial status were studied in two moisture-damaged schools and in two non-damaged schools with longitudinal cross-sectional surveys before and after repairs. Over 1300 schoolchildren aged 6-17 returned questionnaires before and after repairs. After full renovation in one of the damaged schools, elevated concentrations and increased frequencies of indoor air fungi normalized and a significant decrease in the prevalence of 10 symptoms of 12 studied was observed among schoolchildren. No change in microbial conditions was seen after partial repairs in the other damaged school, and only slight improvement was observed in symptom prevalence. The change in the prevalence of symptoms in the reference schools was minor. The results suggest that increased symptom prevalence among schoolchildren in moisture-damaged schools can be managed with proper repair of the moisture damage. PRACTICAL IMPLICATIONS: This longitudinal intervention study showed the positive effects of the moisture and mold damage repairs of a school building on children's health. The success necessitates however, a thorough renovation including appropriate ventilation. Monitoring of airborne viable microbes revealed the damage status of the building and thus could be used as a tool in evaluating the quality of repairs.

Adolescent↗

PubMed2004

Detection of streptomycetes in house dust--comparison of culture and PCR methods.

Streptomycetes are gram-positive, spore producing, filamentous bacteria common in soil, but also present in indoor environments. They are potent producers of secondary metabolites and inducers of inflammatory responses in vitro. Polymerase chain reaction (PCR)- and culture-based detection methods for streptomycetes in house dust samples were compared. A total of 47 dust samples were investigated, and the presence of streptomycetes was determined by cultivation on tryptone-yeast-extract-glucose agar and PCR. The 16S rRNA gene of actinomycete isolates from house dust was partially sequenced to investigate if they belong to the genus Streptomyces. Both PCR and culture showed more frequent occurrence of streptomycetes in moisture-damaged homes, although the results did not correlate well. The occurrence of streptomycetes in house dust was associated with moisture damage of the home. The amount of Streptomyces-specific PCR amplification product was significantly higher in dust from moisture-damaged homes than in homes with no moisture damage (P < 0.05, Mann-Whitney U test). A correlation between streptomycetes and moisture damage, although not statistically significant, was also observed when using binary data, e.g. presence or absence of streptomycetes or moisture damage (P = 0.054 for PCR, and P = 0.127 for culture, Fisher's exact test). Altogether, the presence of streptomycetes in house dust seems to indicate the presence of moisture damage in the building.

Air Pollution, Indoor↗

PubMed2004

Personal exposures to particles and microbes in relation to microenvironmental concentrations.

UNLABELLED: The aim of this study was to compare the personal exposures of particles and microbes with the exposure being assessed by stationary samplers in the main microenvironments, i.e. home and the workplace. A random sample of 81 elementary school teachers in eastern Finland were selected to perform the two wintertime 24-h measurement periods. Particle mass concentration, black smoke (BS) concentration and concentrations of viable and total microorganisms on the sampled filters were determined using personal exposure sampling and microenvironmental measurements in homes and workplaces. In this paper, the correlations between different pollutants in each environment and correlations between personal exposures and home and work concentrations are presented. The results show that personal BS exposures correlated with both home and work BS concentrations. Furthermore, the concentrations of viable fungi and bacteria were related between personal and home concentrations. The time weighted microenvironmental model underestimated the personal exposures of particle mass, viable fungi, total fungi and total bacteria concentrations but the model might satisfactorily assess personal exposure to concentrations of BS and viable bacteria. The mass concentration of total fungi and bacteria was <1% of the total particle mass concentration. PRACTICAL IMPLICATIONS: Stationary samples are only surrogate measures of personal exposures. Personal exposure measurements conducted on individuals' breathing zone are needed to assess the exposure to particles and microbes. The time weighted microenvironmental model is a useful method to assess personal exposure to combustion related particles and viable bacteria concentrations but the model underestimates personal exposures of particle mass, viable fungi, total fungi and total bacteria concentrations.

Adult↗

PubMed2004

The bedding of laboratory animals as a source of airborne contaminants.

In work environments with laboratory animals, the bedding of animals binds the excreta as well as other compounds originating from the animals and their environment. These may be generated into the ambient air when the personnel handle bedding in different procedures. This study compares the dustiness of different types of six clean and four soiled beddings from rat or mouse cages. The dust generation of clean bedding varied from <1 to 25 mg/m(3). When used in the cages of rats or mice for 4 days, the dust concentration of the beddings decreased, increased or stayed the same, depending on the type of bedding and animal species. A decrease in dustiness was, however, more common. The levels in the soiled beddings varied from <1 to 8.6 mg/m(3). In the case of the aspen chip bedding, the contents of bedding used in mouse, rat or rabbit cages were analysed for mesophilic bacteria and fungi, mycobacteria and endotoxins. All of these contaminants were variably found in the bedding samples, the maximal concentrations for bacteria were >6 500 000 colony-forming units (cfu)/g, for fungi 212 000 cfu/g, and for endotoxins 6500 ng/g (81 000 EU/g). The results showed that the bedding of laboratory animals may contain biologically effective compounds, and that these may be distributed into the ambient air depending on the characteristics of the bedding material. The dustiness of different bedding types is an important factor affecting the amount and quality of the occupational exposure of the personnel to airborne contaminants.

Air↗

PubMed2004

The remediation of mold damaged school--a three-year follow-up study on teachers' health.

The health effects in teachers of a mold-damaged school before and during an extensive remediation process were assessed. Health data were collected with self-administered questionnaires from teachers (n=31) working in a moisture and mold damaged school and from the reference group of teachers (n=13) working in a non-damaged school. The questionnaire study was repeated three times. Spirometry was measured in 33 individuals in the spring 1997 and repeated in the spring 1999 and 2000. In the damaged school, a cluster of eight asthma cases was identified, the prevalence of asthma being 26%. Before the remediation, the number of sinusitis episodes was higher (p=0.040) and the mean duration of sick leaves longer (p=0.015) among the study group than in the reference group. A higher prevalence of hoarseness and perceived poor quality of indoor air were reported. During the follow-up, no new asthma cases appeared. After the remediation, bronchitis, conjunctivitis, symptoms of allergic rhinitis and the sum of respiratory infection episodes decreased significantly. Some of the asthmatics had low values in the spirometry but no changes in the lung function were observed at the group level. The remediation of the mold damage had beneficial effects on teachers' health.

Adult↗

PubMed2003

The relation between growth of four microbes on six different plasterboards and biological activity of spores.

Microbial growth on water-damaged building materials is commonly associated with adverse health effects in the occupants. We examined the growth of Stachybotrys chartarum, Aspergillus versicolor, Penicillium spinulosum, and Streptomyces californicus, isolated from water-damaged buildings, on six different brands of plasterboards. The microbial growth was compared with the biological activity of the spores, that is the potential to induce cytotoxicity and proinflammatory mediators in RAW264.7 macrophages. These results showed that the microbial growth on plasterboard depended on both the microbial strain and the brand of plasterboard used. The biological activity of spores appeared to be regulated by different growth conditions on plasterboards so that good microbial growth was associated with a low bioactivity of the spores, whereas the spores collected from plasterboard supporting only weak growth usually were biologically active. Cytotoxicity of either S. chartarum or A. versicolor did not correlate with any particular growth conditions or induced inflammatory responses. Instead, there were positive correlations between cytotoxicity and levels of induced proinflammatory cytokines for P. spinulosum and S. californicus. These data suggest that both the microbial growth on plasterboard and the resulting bioactivity of spores vary and might be affected by changing the growth conditions provided by the plasterboards.

Air Pollution, Indoor↗

PubMed2003

Starch in plasterboard sustains Streptomyces californicus growth and bioactivity of spores.

AIMS: The effects of plasterboard composition on Streptomyces californicus growth and bioactivity of spores were studied. METHODS AND RESULTS: Streptomyces californicus was grown on 13 modified plasterboards under saturated humidity conditions. The total content of fatty acid methyl esters was used for quantifying S. californicus biomass, while the spore-induced cytotoxicity and production of nitric oxide (NO), tumour necrosis factor-alpha, and interleukine-6 (IL-6) in mouse macrophages was used to assess the bioactivity of spores. Removal of starch completely from the plasterboard or only from the core reduced significantly the biomass production and the biological activity of spores in comparison with reference board. The biocide added into the core or on the liner decreased the growth markedly and inhibited the sporulation totally. The biomass production correlated positively with the spore number, cytotoxicity, and production of NO and IL-6. CONCLUSIONS: Streptomyces californicus grew under nutrient limitation on all studied plasterboards. The starch is the major factor enabling S. californicus to grow and to produce biologically active metabolites on plasterboard. SIGNIFICANCE AND IMPACT OF THE STUDY: The composition of building material has an impact on microbial growth and bioactivity of spores which may be involved in complex mechanisms leading to respiratory symptoms in the occupants in moisture damaged buildings.

Carbon↗

PubMed2002

Immunoglobulin G antibodies to moulds in school-children from moisture problem schools.

BACKGROUND: The purpose of the present study was to evaluate mould-specific immunoglobulin G (IgG) antibodies in children exposed to moisture and mould problems in their school, and the association between IgG antibodies and mould allergy, active or passive smoking and respiratory symptoms. METHODS: IgG antibodies were studied to 24 moulds in 93 children from three moisture problem schools and in 33 children from a reference school. The antibodies were measured by enzyme-linked immunosorbent assay and compared to positive adult sera. RESULTS: There were no significant differences in mould-specific IgG concentrations between exposed and non-exposed school-children. Antibodies to moulds common in moisture damaged buildings were associated with allergic diseases, as well as with mould-specific immunoglobulin E (IgE) or skin prick test (SPT) findings. Aspergillus fumigatus and A. versicolor were the moulds with the most consistent findings. Active and passive smoking were associated with low levels of antibodies to many moulds. Though the association between asthma, wheezing or cough symptoms, and IgG to moulds was not significant, 7 (39%) of the 18 children with multiple (> 7) elevated IgG findings suffered from asthma or wheezing. CONCLUSIONS: Allergy was, but asthma was not, associated with IgG antibodies to the moulds that can be found in moisture damaged buildings. However, no association was found between IgG antibodies to moulds and exposure to moisture and moulds in school.

Adolescent↗

PubMed2002

Indoor air microbes and respiratory symptoms of children in moisture damaged and reference schools.

Microbial indoor air quality and respiratory symptoms of children were studied in 24 schools with visible moisture and mold problems, and in eight non-damaged schools. School buildings of concrete/brick and wooden construction were included. The indoor environment investigations included technical building inspections for visible moisture signs and microbial sampling using six-stage impactor for viable airborne microbes. Children's health information was collected by questionnaires. The effect of moisture damage on concentrations of fungi was clearly seen in buildings of concrete/brick construction, but not in wooden school buildings. Occurrence of Cladosporium, Aspergillus versicolor, Stachybotrys, and actinobacteria showed some indicator value for moisture damage. Presence of moisture damage in school buildings was a significant risk factor for respiratory symptoms in schoolchildren. Association between moisture damage and respiratory symptoms of children was significant for buildings of concrete/brick construction but not for wooden school buildings. The highest symptom prevalence was found during spring seasons, after a long exposure period in damaged schools. The results emphasize the importance of the building frame as a determinant of exposure and symptoms.

Actinobacteria↗

PubMed2002

Diversity of streptomycetes in water-damaged building materials based on 16S rDNA sequences.

AIMS: The diversity of streptomycetes in two different types of water-damaged building materials was investigated. METHODS AND RESULTS: Direct PCR amplification of 16S rDNA from DNA isolated from building materials, cloning of the fragments and sequence analysis were used. In the phylogenetic analysis of the variable gamma region of the PCR amplification products, the sequences affiliated with five groups. CONCLUSIONS: Several different sequences were found in both materials, suggesting the presence of several species. Also, previously unknown sequences were detected, although all the sequences clustered together with sequences of known species. SIGNIFICANCE AND IMPACT OF THE STUDY: Streptomycetes are known as indicators for moisture and mould damage in buildings and potential health risk, but their diversity in indoor environments is still unknown.

Cloning, Molecular↗

PubMed2002

Fungal spores as such do not cause nasal inflammation in mold exposure.

The increased frequency of respiratory symptoms and diseases among sawmill workers has been linked to occupational exposure to airborne contaminants, especially to different fungi. Similar adverse health effects, together with elevated levels of inflammatory mediators in the nasal lavage (NAL) fluid, have been detected in people working in mold-damaged buildings. However, the indoor fungal spore concentrations in moldy houses are much lower than those in sawmills. To study the effect of fungal spores as such on the inflammatory markers in the NAL fluid, we conducted a similar study in sawmill workers who had an intense exposure to fungal spores. NAL was performed in 11 sawmill workers both during high occupational microbial exposure and during their vacation. Concentrations of nitric oxide (NO), tumor necrosis factor-alpha (TNFalpha), interleukin (IL)-4, IL-5, and IL-6 in NAL fluid were analyzed, and occupational exposure to inhalable dust, fungal spores, endotoxins and terpenes was confirmed by personal monitoring during the day of sampling. In addition, health data were collected with a questionnaire. Personal exposures to fungal spores varied from 2 x 10(5) spores/m(3) to 1.5 x 10(6) spores/m(3) (mean 7 x 10(5) spores/m(3)). Concentrations of inhalable dust, endotoxins, and terpenes were relatively low. There were no differences between work and vacation in the concentrations of NO and proinflammatory cytokines in NAL fluid or in the reporting of symptoms, and the levels were lower than in workers at a moldy school building. However, the concentration of TNFalpha in the NAL fluid was positively correlated with the concentration of terpenes in the working environment (r =.768; p =.006). These results show that microbial exposure as such does not invariably result in inflammatory changes detectable with the NAL method. We suggest that the type of microbial flora or microbial products in the occupational environment determines the proinflammatory potency of microbial exposure.

Adult↗

PubMed2002

Airborne contaminants in conventional laboratory rabbit rooms.

Besides the well known allergens, several other risk factors may exist for health in a laboratory animal unit. The exposure to these factors may be significant in animal units with poor general or local ventilation systems. Moreover, means to prevent the distribution of airborne contaminants may be limited in animal units housing rabbits or other bigger laboratory animals. Airborne contaminants in conventional laboratory rabbit rooms were sought to evaluate the occupational exposure of animal care personnel. Concentrations of airborne dust, bacteria, fungi, ammonia and endotoxins were measured during 2 days in three phases: before working activities began, during them and afterwards. Both stationary and some personal samples were taken. All of the contaminants sought were found in the rabbit room air. When compared to reported levels in farm animal production areas, the concentrations measured were generally low. However, moderate or high levels of airborne bacteria and fungi were found occasionally during work routines. Airborne contaminants should be considered as a potential occupational health risk for persons working with laboratory animals.

Air Microbiology↗