Biomedical subjects

B Brunekreef

Publications and source records attributed to B Brunekreef.

At least 145 records · Page 8Linked to original sources

PubMed1994

Fungal propagules in house dust. I. Comparison of analytic methods and their value as estimators of potential exposure.

The presence of viable mold propagules in house dust was investigated by 10 different analytic methods, in order to determine to what extent different results are obtained when different analytic methods are used. Moreover, the value of this measurement as an estimator of the potential exposure to fungi in epidemiologic studies was assessed. Floor and mattress dust was sampled in 60 homes in The Netherlands during autumn 1990. For investigation of the variability in time, sampling was repeated in 20 homes after 6 weeks. Each analytic method is characterized by a unique combination of culture medium, suspension medium, and dilution step. The highest mean number of colony-forming units (CFU)/g dust was obtained by suspension of at least 100 mg dust in a peptone or sucrose solution in a ratio of 1:50 (w/w), followed by 10-fold dilution and plating on DG18 agar (geometric mean (GM) approximately 60,000 CFU/g dust). The lowest mean number of CFU/g dust was obtained by direct plating of 30 mg dust on V8 agar (GM approximately 5300 CFU/g dust). The mean coefficient of variation of duplicate analyses varied from 11%, for suspension in sucrose and plating on DG18 agar, to 27%, for suspension and dilution in sucrose in combination with V8 agar. The highest mean number of species isolated was obtained by direct plating of 30 mg dust on DG18 agar (mean number of species: 17). Suspension and dilution on DG18 or V8 agars yielded an average of approximately six species. In duplicate analyses, the mean percentage of agreement for the species isolated varied from approximately 35%, for suspension and dilution, to 60%, for direct plating.(ABSTRACT TRUNCATED AT 250 WORDS)

Colony Count, Microbial↗

PubMed1994

Fungal propagules in house dust. II. Relation with residential characteristics and respiratory symptoms.

As part of a case-control study on the relation between home dampness and respiratory symptoms of children, house-dust samples were collected from bedroom floors and mattresses in 60 homes in The Netherlands. The house-dust samples were analyzed for the presence of fungal propagules by plating 30 mg of dust directly onto DG18 agar. A checklist and questionnaire were used to obtain information on the home characteristics and occupant behavior that may have an effect on the presence of fungal propagules in house dust. The geometric mean (GM) numbers of colony-forming units (CFU)/g dust collected from the floors was 8990. The number of CFU/g dust was significantly higher in dust from carpeted floors than in dust from smooth floors (GM, respectively, 12,880 CFU/g dust and 3530 CFU/g dust). The GM number of CFU/g dust collected from mattresses was 6760. Overall, the mean numbers of CFU/g dust collected from floors and mattresses were higher in bedrooms where damp spots mold growth, or both were observed. However, these differences were not statistically significant. The relation between home characteristics and the number of CFU/g dust of the most frequently isolated mold species (n = 17), including Alternaria alternata, Cladosporium cladosporioides, Penicillium brevicompactum, and Scopulariopsis brevicaulis, was also investigated. Only the type of flooring had a significant and consistent effect on the number of CFU/g floor dust of the different mold species.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗

PubMed1994

Peak-flow variability in asthmatic children is not related to wall-to-wall carpeting on classroom floors.

The hypothesis was tested that wall-to-wall carpets on school classroom floors have a negative effect on the respiratory health of asthmatic children. Asthmatic patients (n = 98) were selected from the records of the Sophia Children's Hospital in Rotterdam. The patients were between 5 and 11 years old. All children had peak-flow measurements three times a day for a 1-month period. The parents of the children completed a diary in which respiratory symptoms and medication use were recorded daily for the same period. Dust samples were taken from classroom floors, living-room and bedroom floors, and mattresses of the children. The dust samples were analyzed for Der p I content, the major allergen of the house-dust mite Dermatophagoides pteronyssinus. The results of the study showed that there was no significant difference between children visiting schools with or without carpeted classroom floors in peak-flow variability, acute respiratory symptoms, or medication use. The Der p I content of dust collected from classroom floors was much lower than of dust collected from homes. There was a significant correlation between peak-flow variability and mattress dust Der p I content in asthmatic children sensitized to dust mites, but not between peak-flow variability and classroom floor dust Der p I content. We concluded that carpeted classroom floors do not contribute to asthma symptom severity, possibly because of the low levels of Der p I on them.

Allergens↗

PubMed1994

Respiratory effects of low-level photochemical air pollution in amateur cyclists.

A group of male amateur cyclists was studied in the summer of 1991 in the east of the Netherlands. Lung function was measured before and after training sessions or competitive races on a number of occasions. Continuous heart rate monitors were employed to document exercise levels. Heart rate averaged 161 beats/min during training, and 176 beats/min during races. Exercise duration averaged 75 min. Ozone concentrations during exercise were obtained from the nearest stations of the National Monitoring Network. The difference between pre- and postexercise lung function values was related to these ozone concentrations. Ozone concentrations were low on most occasions with an average of 87 micrograms/m3 and a maximum of 195 micrograms/m3. The difference between pre- and postexercise lung function was found to be negatively related to the ozone concentration during exercise. When all observations obtained at ozone concentrations higher than 120 micrograms/m3 were removed from the analysis, the relationship with ozone was still significant. The data also suggested that effects of ozone on lung function were stronger in midsummer than in the late summer. The difference between pre- and postexercise acute symptoms was positively related to ozone, for shortness of breath, chest tightness, and wheeze. Cough and eye irritation were not related to ozone. These results indicate that in healthy young men vigorously exercising outdoors, ozone is related to lung function changes and acute respiratory symptom changes at low levels of exposure.

Adolescent↗

PubMed1994

House dust mite allergen in bedroom floor dust and respiratory health of children with asthmatic symptoms.

The purpose of this study was to investigate the effects of house dust mite allergen in bedroom floor dust on respiratory health of children with asthmatic symptoms. Two hundred and twenty eight school children with reported attacks of shortness of breath with wheezing in the past year and/or with doctor-diagnosed asthma, were included in the study. Data on home characteristics, both past and present, were obtained. These included data on allergen avoidance measures because of the child's respiratory health. Dust samples were taken from the child's bedroom floor, and the allergen Der p I of the house dust mite Dermatophagoides pteronyssionus was measured. Health diaries were kept over 4 weeks. Acute respiratory symptoms and medication usage were recorded daily. Peak expiratory flow (PEF) was measured using Mini-Wright peak flow meters three times daily. Levels of Der p I in dust from carpeted floors were significantly higher than in dust from smooth floors. We found a positive relationship of Der p I levels, in floor dust collected from carpeted floors, with PEF-variability and also with the prevalence of wheeze, shortness of breath, and attacks of shortness of breath with wheezing during the observation period. The effects on peak flow variability was larger in children allergic to house dust than in children not allergic to house dust. Peak flow variability was significantly increased at exposure levels well below 10,000 ng Der p I.g-1 dust, which has been suggested to be a "threshold" for increased risk symptoms among sensitized asthmatics.(ABSTRACT TRUNCATED AT 250 WORDS)

Allergens↗

PubMed1993

Acute effects of ambient ozone on pulmonary function of children in The Netherlands.

In the spring and summer of 1989 an epidemiologic study was conducted to evaluate the acute effects of photochemical air pollution episodes on pulmonary function of children living in three nonindustrial towns in the Netherlands. Spirometry was performed repeatedly in the schools of the children, mostly during the morning hours. Data from 533 children having more than four valid pulmonary function tests were included in the analyses. The association between previous-day ambient ozone concentration and pulmonary function was evaluated, using individual linear regression analysis and subsequent evaluation of the distribution of individual regression coefficients. One hour maximum ambient ozone concentrations frequently exceeded 160 micrograms/m3 but were all lower than the Dutch Air Quality Guideline of 240 micrograms/m3 for all three populations. Significant negative associations of previous-day ambient ozone with FVC, FEV1, peak expiratory flow (PEF), and maximal midexpiratory flow (MMEF) were observed. There were indications of systematic differences in responses among the children. Children with chronic respiratory symptoms did not have a stronger response than children without these symptoms.

Air Pollution↗

PubMed1993

Effect of ambient winter air pollution on respiratory health of children with chronic respiratory symptoms.

The acute respiratory effects of ambient air pollution were studied in a panel of 73 children with chronic respiratory symptoms in the winter of 1990 to 1991. The participating children were selected from all children aged 6 to 12 yr in Wageningen and Bennekom, two small, nonindustrial towns in the east of the Netherlands. Peak flow was measured twice daily with MiniWright meters. A diary was used to register the occurrence of acute respiratory symptoms and medication use by the children. Exposure to air pollution was characterized by the ambient concentrations of sulfur dioxide (SO2), nitrogen dioxide (NO2), black smoke (BS), and particulate matter less than 10 microns (PM10). Associations between air pollution concentrations and health outcomes were analyzed using time series analysis. During the study period an air pollution episode occurred, with moderately elevated concentrations of PM10 and SO2. There were 6 days with 24-h average PM10 concentrations in excess of the WHO suggested lowest observed effect level of 110 micrograms/m3. After adjustment for ambient temperature, there were small but statistically significant negative associations of PM10, BS, and SO2 with both morning and evening PEF. There was a consistent positive association between PM10, BS, and SO2 with the prevalence of wheeze and bronchodilator use. Overall, the observed associations suggest a mild to moderate response to these moderately elevated levels of air pollution in a group of potentially sensitive children.

Air Pollution↗

PubMed1993

The relationship between low-level air pollution exposure and short-term changes in lung function in Dutch children.

Following air pollution episodes in the winters of 1985 and 1987, a series of studies was initiated to investigate short-term changes in health status in children in relationship to short-term changes in air pollution concentrations. Air pollution exposure was characterized by measurements of SO2, NO2, PM10, nitrate, sulfate, H+, and HONO. Panels of unselected children were studied in four winters (1987-1991). Lung function was measured repeatedly with spirometry in these children. In the winter of 1990/1991, a panel of children with chronic respiratory symptoms was studied as well, with repeated observations of Peak Expiratory Flow made at the home. The three winters of 87/88, 88/89 and 89/90 were very mild; no air pollution episodes with long range transport from the east occurred. In these three winters, lung function was measured on 86 different days. Altogether, over 800 children participated. H+ concentrations (expressed as H2SO4) were generally below 0.6 microgram/m3, with a maximum of only 3 micrograms/m3. Daily mean SO2 concentrations never exceded 100 micrograms/m3 in this period. Nevertheless, lung function in these unselected children was found to decrease with increasing levels of especially particulate matter air pollution. In the winter of 1990/1991, a minor air pollution episode occurred. Maximum SO2 and PM10 concentrations were 105 micrograms/m3 and 174 micrograms/m3 respectively. This episode was associated with decreased lung function in a group of about 112 unselected children. There was also a relationship with decreased daily PEF readings in a panel of 73 children with chronic respiratory symptoms.

Air Pollutants↗

PubMed1992

Associations between questionnaire reports of home dampness and childhood respiratory symptoms.

The relationship between home dampness and respiratory health was studied in two populations of children of 6-12 years old, living in the south east of the Netherlands. In one study, lung function was measured at the schools, and in both studies, information on respiratory symptoms was collected from a self-administered questionnaire completed by the parents of the children. Information on home dampness was collected by questionnaire. Information on other potential indoor determinants of respiratory health, like (sources of) nitrogen dioxide and smoking in the home was collected by questionnaire as well. Respiratory symptoms were found to be associated with home dampness. There was a weak, negative association between MMEF and reporting of mould in the home. Several potential biases were evaluated. It was not considered likely that the results could be explained by information, selection or confounding bias. However, further work is needed to conclusively exclude these biases, and to develop objective measures of home dampness for use in epidemiologic studies.

Asthma↗

PubMed1992

Pets, allergy and respiratory symptoms in children.

The relationship between pet ownership and respiratory allergy and symptoms was investigated in a population of 3344 Dutch children of 6-12 years old. Pet ownership was defined by the presence of cats, dogs, birds and/or rodents in the home. The reported prevalence of respiratory allergy and symptoms was lower among children of current pet owners than among children of parents who owned no pets. When past pet ownership was taken into account, however, a different picture emerged. The lowest prevalence of respiratory allergy and symptoms was found in children of current pet owners who had no pets in the past. The next lowest prevalence was found in children of current pet owners who had had pets in the past also. The next highest prevalence was found in children who never had pets in their life. The highest prevalence of reported pet allergy, chronic cough, wheeze, attacks of shortness of breath with wheezing, and doctor-diagnosed asthma was found in children who had pets in the past but not anymore. Past cat ownership especially was associated with a high prevalence of pet allergy and doctor-diagnosed asthma. Almost 2% of the population reported to never have owned pets for health reasons, and more than 12% reported removing pets from the home for health reasons in the past. These results show that selective avoidance and removal of pets leads to distortions of cross-sectional associations between pet ownership and respiratory allergy and disease among children.

Animals↗

PubMed1992

Damp housing and adult respiratory symptoms.

The relationship between home dampness and adult respiratory symptoms was investigated using data from a parent-administered questionnaire on childhood respiratory symptoms that also included questions on parental respiratory symptoms. Questionnaires were returned by the parents of 3344 children living in the town of Helmond, The Netherlands. The response was 73%. Home dampness was characterized by reports of damp stains or mould growth on indoor surfaces and was reported by 23.6% and 15.0% of the study population, respectively. Of the homes, 25.4% had dampness and/or mould. Information about respiratory symptoms was collected for the mothers and fathers of a population of 6-12-year-old schoolchildren. Symptoms analysed were cough, phlegm, wheeze, asthma, and allergy to pollen or house dust. Cough and phlegm in both men and women were found to be strongly associated with living in a damp home. Weaker associations were found for wheeze and asthma, and there was little association between living in a damp home and allergy to pollen or house dust. Current smoking was strongly associated with cough, phlegm and wheeze in both men and women. Smoking was inversely associated with allergy to pollen or house dust, suggesting that allergic subjects do not start smoking, or give up the habit. The results suggest that the association between home dampness and respiratory symptoms previously reported for children also applies to adults. Suggested mechanisms include exposure to biological contaminants produced by fungi or house dust mites, but it has not yet been documented to what extent these exposures are responsible.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1992

Presence of viable mould propagules in indoor air in relation to house damp and outdoor air.

The presence of viable mould propagules in indoor air was investigated using the N6-Andersen sampler in combination with DG18-agar, in relation to house damp (characterized with a checklist) and in relation to the presence of moulds in outdoor air. The first part of the study was conducted in 46 houses in the autumn of 1987, the second part in 84 houses in May 1989. Further, in the second part, the results obtained with settlement plates (OPD) were compared with those obtained with the N6-Andersen sampler. The number of CFU/m3 in the indoor and outdoor air varied widely. A large variety of mould genera and species was isolated. Species of Cladosporium, Penicillium and Wallemia predominated. The variability in time was high and the reproducibility of the measurements in terms of CFU/m3 and of species isolated was only moderate. The low predictive value of these measurements limits their use in epidemiological studies of the relationship between exposure to moulds and respiratory symptoms. Overall, the geometric mean concentration was somewhat higher outdoors than indoors. However, the clear differences found between the number of CFU/m3 belonging to different mould species in in- and outdoor air show that the presence of viable mould propagules in indoor air is not simply a reflection of the presence of moulds in outdoor air. The presence of moulds in indoor air was only weakly related to house damp as characterized by the checklist. High, statistically significant correlations were found between the CFU yield obtained with the OPD and the CFU/m3 yield obtained with the N6-Andersen sampler.(ABSTRACT TRUNCATED AT 250 WORDS)

Air Pollutants↗

PubMed1992

Reproducibility of childhood respiratory symptom questions.

The reproducibility of answers to childhood respiratory symptom questions was investigated by administering two childhood respiratory symptom questionnaires twice, with a one month interval, to the same population of Dutch school children. The questionnaires were completed by the parents of 410 children from 6-12 yrs old. One questionnaire was developed by the World Health Organization (WHO). The other questionnaire was developed for use by school health services and was based mainly on the American Thoracic Society (ATS) questionnaire for respiratory symptoms in childhood. It was called the Child Health Care (CHC) Questionnaire. Half of the parents received a questionnaire in which the WHO questions came first on both occasions, the other half a questionnaire in which the CHC questionnaire came first on both occasions. The reproducibility of the answers was assessed by calculating Cohen's Kappa, a chance-corrected measure of association. Questions about "wheeze", "asthma", "bronchitis", "cough and phlegm", and "pneumonia" were found to give good to excellent reproducibility, with Kappa values ranging from 0.60-0.96. Questions about "phlegm", "cough", "chest congestion" and "runny/congested nose" were less satisfactory in this respect, with Kappa values generally well below 0.60. The reproducibility of the answers did not depend on the order in which the questionnaires were administered, on the gender or age of the child, or on the smoking habits or educational level of the parents.

Child↗

PubMed1992

Time trends in repeated spirometry in children.

In a study on acute health effects of air pollution in the Netherlands, pulmonary function has been measured repeatedly in children aged 7-11 yrs. In study periods of approximately 3 months, 6-10 tests have been made in a group of 1,621 children. The spirometric data have been examined for the presence of trends of pulmonary function with day of study, independent of air pollution. Peak expiratory flow (PEF) increased more than expected from normal lung growth, whereas for maximal mid-expiratory flow (MMEF) a decrease with time was observed. For forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) a smaller than expected increase with time was observed. The observed deviation from the expected pattern was larger for the children with a one week interval between successive tests than for the children with a three week interval. For FVC and FEV1 a non-linear relationship with time was observed, for PEF and MMEF this relationship was approximately linear. The particular changes of spirometric variables with time need to be taken into account when repeated lung function tests are performed to investigate acute effects of air pollution exposure.

Air Pollution↗

PubMed1991

Sensitive subgroups and normal variation in pulmonary function response to air pollution episodes.

The Clean Air Act requires that sensitive subgroups of exposed populations be protected from adverse health effects of air pollution exposure. Hence, data suggesting the existence of sensitive subgroups can have an important impact on regulatory decisions. Some investigators have interpreted differences among individuals in observed pulmonary function response to air pollution episodes as evidence that individuals differ in their sensitivity. An alternative explanation is that the differences are due entirely to normal variation in repeated pulmonary function measurements. This paper investigates this question by reanalyzing data from three studies of children exposed to air pollution episodes to determine whether the observed variability in pulmonary function response indicates differences in sensitivity or natural interoccasion variability. One study investigated exposures to total suspended particulates (TSP), the other two investigated exposure to ozone. In all studies, each child's response to air pollution exposures was summarized by regressing that child's set of pulmonary function measurements on the air pollution concentrations on the day or days before measurement. The within-child and between-child variances of these slopes were used to test the hypothesis of variable sensitivity. Regression slopes did not vary significantly among children exposed to episodes of high TSP concentration, but there was evidence of heterogeneity in both studies of ozone exposures. The finding of heterogeneous response to ozone exposure is consistent with the epidemiologic and chamber studies of ozone exposures, but the lack of evidence for heterogeneous response to TSP exposures implies that observed variation in response can be explained by sampling variability rather than the presence of sensitive subgroup.

Air Pollution↗

PubMed1991

Childhood asthma and the indoor environment.

To investigate the influence of indoor air quality on respiratory health, a questionnaire-based study of 17,962 Canadian schoolchildren in kindergarten through grade 2 was carried out in 1988. The present report focuses on associations between several indoor environmental factors and childhood asthma. Increased reports of physician-diagnosed asthma were significantly associated (p less than 0.001) with exposure to environmental tobacco smoke (OR = 1.4), living in a damp home (OR = 1.5), the use of gas for cooking (OR = 2.0) and the use of a humidifier (OR = 1.7). Wheezing without a diagnosis of asthma also was associated (p less than 0.01) with environmental tobacco smoke (OR = 1.4, home dampness (OR = 1.6) and humidifier use (OR = 1.4), but not with gas cooking. Thus, several modifiable risk factors for respiratory illness may exist in Canadian homes. Further research is required to determine the nature of these cross-sectional observations.

Air Pollution, Indoor↗

PubMed1990

[The effect of elevated ozone levels in the ambient air on lung function of children engaged in sports].

In the summer of 1989, ozone levels in the ambient air were regularly found to be increased in The Netherlands. The question was studied whether this affected pulmonary function of children aged 7 to 12 years practising sports in the open air. Before and after sessions of training in the open air, the peak expiratory flow rate was determined using peak flow meters (mini-Wright). This was done on 37 different days with varying ozone concentrations. Measurements were carried out on four or more days in a total of 65 children. No correlation between ozone concentration during training and differences between pre- and post-training peak flows was found. No correlation was found either between the maximal ozone concentration on a given day and the peak flow at the end of training on that day. However, a negative correlation was found between the maximal ozone concentration on the day preceding the pulmonary function tests and the peak flow after the training.

Air Pollutants↗

PubMed1990

Estimated soil ingestion by children.

The amount of soil ingested by young children was estimated by measuring the titanium, aluminum, and acid-insoluble residue in soil and feces. As intake of each of these tracers is also possible from sources other than soil ingestion, the amount of soil ingested was estimated to be not higher than the lowest of the three separate estimates. This estimate, the limiting tracer method (LTM) value, was then corrected for the similarly calculated mean LTM value for a group of hospitalized children without access to soil and dust. The study groups included children in three different environmental situations: day-care centers, campgrounds, and hospitals. The day-care center groups were sampled twice. From these groups, 162 children produced usable feces samples during both sampling periods. The camping groups and the hospitalized (control) group were sampled once. For the day-care center groups, the estimated geometric mean soil intake varied from 0 to 90 mg/day and for the camping groups these estimates ranged from 30 to 200 mg/day (in dry weight). Using estimates of the "true" between-child GSD values, the 90th percentile of the estimated soil intakes was shown to be typically 40-100 mg/day higher than the geometric means of these estimates. In the day-care center groups few correlations with the geometric mean LTM values were found for variables concerning living conditions, mouthing behavior, playing habits, etc. A strong correlation was found with weather. During dry weather the younger children especially showed higher LTM values. In the camping group the weather also influenced the mean LTM value only in the younger age groups. Analysis of variance showed that a single LTM value of a child has a low predictive value with regard to the LTM value of the next few days or that of a few months later. Therefore it seems reasonable to use group statistics as estimates of soil ingestion in health risk assessments of soil pollution incidents.

Aluminum↗