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Biomedical subjects

B Brunekreef

Publications and source records attributed to B Brunekreef.

At least 163 records · Page 9Linked to original sources
PubMed1990

Indoor nitrogen dioxide exposure and children's pulmonary function.

Elevated concentrations of nitrogen dioxide (NO2) are produced in the home by the use of unvented gas appliances. In studies on potential health effects of indoor exposure to NO2, exposure has mostly been estimated from the presence or absence of sources like gas cookers in the home. This leads to misclassification of exposure, as NO2 concentrations in the home depend also on source use, ventilation habits, time budgets, etc. The availability of cheap, passive monitoring devices has made it possible to measure indoor concentrations of NO2 directly in health effects studies, albeit with averaging times of one to several days. So far, it has not been evaluated whether this increases the sensitivity of a study to detect health effects of NO2. In this paper, a comparison is made between NO2 sources and weekly average indoor NO2 measurements, as predictors of pulmonary function in a study among children aged 6-12 years. The relationship between exposure and lung functions was found to be generally non-significant in this study. The results further suggested that in this study, measuring indoor NO2 concentrations with passive monitors offered no advantage over the simple use of source presence as exposure variable.

Air Pollutants↗
PubMed1990

Enumeration and identification of airborne viable mould propagules in houses. A field comparison of selected techniques.

A number of techniques for the enumeration and identification of viable mould propagules in the indoor air of houses were evaluated in order to document to what extent different results are obtained when different methods are used. A comparison was made between the results obtained with five commercially available air sampling devices (Slit-to agar sampler, N6-Andersen sampler, Surface Air System sampler, Reuter Centrifugal Air sampler, Gelatine Filter sampler) and a non-volumetric sampler (the Open Petri Dish), in combination with four culture media (malt extract agar, dichloran glycerol-18 agar, oxytetracycline glucose yeast extract agar and dichloran rose bengal chloramphenicol agar). The coefficients of variation were high (generally greater than 20%) for all combinations. Statistical analysis showed that the Slit sampler and the N6-Andersen sampler in combination with DG18 and MEA gave the best precision and the highest yield in terms of colony forming units per square cubic meter of air (CFU/m3) and number of species isolated.

Air Microbiology↗
PubMed1990

Respiratory health effects of the indoor environment in a population of Dutch children.

The effect of indoor exposure to nitrogen dioxide on respiratory health was studied over a period of 2 yr in a population of nonsmoking Dutch children 6 to 12 yr of age. Lung function was measured at the schools, and information on respiratory symptoms was collected from a self-administered questionnaire completed by the parents of the children. Nitrogen dioxide was measured in the homes of all children with Palmes' diffusion tubes. In addition, information on smoking and dampness in the home was collected by questionnaire. There was no relationship between exposure to nitrogen dioxide in the home and respiratory symptoms. Respiratory symptoms were found to be associated with exposure to tobacco smoke and home dampness. There was a weak, negative association between maximal midexpiratory flow (MMEF) and exposure to nitrogen dioxide. FEV1, peak expiratory flow, and MMEF were all negatively associated with exposure to tobacco smoke. Home dampness was not associated with pulmonary function. Lung function growth, measured over a period of 2 yr, was not consistently associated with any of the indoor exposure variables. The development of respiratory symptoms over time was not associated with indoor exposure to nitrogen dioxide. There was a significant association between exposure to environmental tobacco smoke in the home and the development of wheeze. There was also a significant association between home dampness and the development of cough.

Air Pollutants↗
PubMed1990

Presence of viable mould propagules in the indoor air of houses.

The aim of the first part of this study was to select the optimal technique for the enumeration and identification of viable mould propagules in the indoor air of houses. A comparison was made between the results obtained with six commercially available air sampling devices in combination with four culture media. The optimal technique was defined as the technique with the best precision and the highest yield. The coefficients of variation were high (generally greater than 20%) for all combinations. Statistical analysis showed that the Slit sampler and the N6-Andersen sampler in combination with DG18 and MEA gave the best precision and the highest yield in terms of CFU/m3 and number of species isolated. In the second part of this study the presence of viable mould propagules in the indoor air of 46 houses in relation to the dampness of these houses was investigated, using the N6-Andersen sampler in combination with DG18. To assess the variability in time, the measurements were repeated after five weeks. Overall, between the two periods no difference was found between the average number of CFU/m3 in the investigated homes. However, the variation between homes was much smaller than the variation within homes. The mean number of CFU/m3 was somewhat higher in "damp" houses than in "dry" houses. However, this difference was not significant. Furthermore, there were no demonstrable differences in the presence of specific mould species in "damp" and "dry" houses.

Air Microbiology↗
PubMed1990

Effects of air pollution episodes on pulmonary function and respiratory symptoms.

In January 1985, a decline of primary school children's pulmonary function was observed during an air pollution episode. Ambient 24 hour average levels of SO2, TSP and RSP were in the range of 200-250 micrograms/m3. The response persisted for at least two weeks. In January 1987, again a decline of school children's pulmonary function was observed associated with an air pollution episode. Levels of TSP were about as elevated as in the 1985 episode. Two weeks after the episode, lung function levels were even lower than during the episode. In June 1987 a long term study was started to investigate potential effects of winter and summer air pollution episodes on pulmonary function and occurrence of acute respiratory symptoms of primary school children. An important issue for this study is the characterization of short term variation of lung function in absence of air pollution. Exposure is characterized by ambient levels of several gases (SO2, NO2, O3, HNO3), PM10, TSP and components of particulate matter (SO4(2-), NO3-, H-, NH4+). Sampling is being conducted on a daily basis to obtain a continuous exposure estimate. In the winter of 1987/1988, no air pollution episodes were observed. The study will continue through the winters of 1988/1989, and 1989/1990.

Air Pollution↗
PubMed1990

Lung growth of pre-adolescent children.

Lung growth was studied in 420 Dutch children aged 6-11 yrs. Forced vital capacity (FVC), forced expiratory volume in one second (FEV1), peak expiratory flow (PEF) and maximal mid-expiratory flow (MMEF) were measured four times over a 2.5 yr period with a rolling-seal spirometer. In boys, pulmonary function increased with approximately the same velocity at all ages studied. In girls, however, the growth velocities of FVC and FEV1 increased markedly at age 10 yrs, and growth velocities of PEF and MMEF had increased already at age 9 yrs. The minimum pulmonary function growth velocity could not be determined from the available data in boys. In girls, the minimum pulmonary function growth velocities preceded the minimum height growth velocity at the onset of the pubertal growth spurt. All lung function growth rates were significantly associated with the growth rate of height. In girls, the growth rate of FVC was also associated with the weight growth rate. There was also some association between the growth rates of PEF and MMEF and age. In boys, there was a negative association between age and the growth rates of FVC and FEV1, after adjustment for the growth rate of height.

Body Height↗
PubMed1989

Estimation of maximum expiratory flow-volume variables in children.

Different protocols for pulmonary function testing were evaluated in 611 children, 6-9 years old. Attention was paid to the necessary minimum number of acceptable maneuvers, the necessary maximum number of attempts, and the best of seven different methods for summarizing variables from maximum expiratory flow-volume (MEFV) curves. The results of the study indicate that it is not useful to continue pulmonary function testing after eight attempts. The differences between the results from three or five acceptable maneuvers are not substantial for any method; in children, obtaining three acceptable curves seems sufficient. When flow variables are selected from one acceptable curve, as in the American Thoracic Society (ATS) guidelines, the reproducibility is somewhat less good than in methods in which results of various curves are averaged or selection is made from different curves. The method that has been recommended by the European Community for Coal and Steel for the selection of MEFV variables in teenagers and adults in Europe, was also demonstrated to be suitable for younger children.

Child↗
PubMed1989

Potentially allergenic airborne particles in the vicinity of a yeast and penicillin production plant.

Potential health risks of exposure to emissions of a yeast and penicillin production plant were investigated by measuring viable particles and protein contents of particles in ambient air. The results showed a clear decrease of the downwind number of yeast colony-forming units with increasing distance from the source. Upwind the number of yeast colony-forming units was zero. Identification showed that nearly all yeast were of the species Saccharomices cerevisiae. Such a trend could not be found for the total number of colony-forming units (yeasts, molds, and bacteria) although the upwind concentration was slightly lower than the downwind concentration. The downwind protein concentration was significantly elevated compared to the upwind concentration.

Air Pollutants, Occupational↗
PubMed1989

Pulmonary function changes associated with an air pollution episode in January 1987.

In January 1987, an air pollution episode occurred in central and western Europe. Levels of SO2, NO2, black smoke, sulphates and other components were elevated, with 24 hour average concentrations of SO2 reaching a maximum of close to 300 micrograms/m3 in an area in the southeast of the Netherlands. Pulmonary function was measured in a group of children of 6-12 years old at the end of the episode, and also two and three and a half weeks after the episode. A baseline lung function value was obtained about three months before the episode. Pulmonary function growth between baseline and retest dates was estimated from a simple growth model which was validated using measured pulmonary function growth data from a longitudinal study. A decline of pulmonary function (FVC, FEV1 and PEF) from predicted baseline levels was observed, starting on the last day of the episode. Two weeks after the episode, FVC, FEV1, PEF and MMEF were all decreased, and three and a half weeks after the episode, there was still a deficit compared to predicted baseline levels for FVC and FEV1.

Air Pollution↗
PubMed1989

Respiratory symptoms in damp homes. A pilot study.

The association between living in damp homes and the prevalence of health symptoms was investigated in a population of 519 occupants (adults and children) of 185 homes. Positive associations were found between the reporting of respiratory and some other health symptoms and living in a damp home. The concentration of variable mould spores in indoor air was measured, using modified Andersen samplers, in the living rooms of a sample of 36 homes. The results were compared with the occurrence of dampness characteristics in their homes as reported by the occupants. Homes with at least two dampness characteristics showed higher average spore counts and higher prevalence of respiratory symptoms.

Allergens↗
PubMed1989

Home dampness and respiratory morbidity in children.

This study examined the relationship between measures of home dampness and respiratory illness and symptoms in a cohort of 4,625 eight- to 12-yr-old children living in six U.S. cities. Home dampness was characterized from questionnaire reports of mold or mildew inside the home, water damage to the home, and the occurrence of water on the basement floor. Symptoms of respiratory and other illness were collected by questionnaire. Pulmonary function was measured by spirometry. Signs of home dampness were reported in a large proportion of the homes. In five of the six cities, one or more of the dampness indicators were reported in more than 50% of the homes. The association between measures of home dampness and both respiratory symptoms and other non-chest illness was both strong and consistent. Odds ratios for molds varied from 1.27 to 2.12, and for dampness from 1.23 to 2.16 after adjustment for maternal smoking, age, gender, city of residence, and parental education. The relationship between home dampness and pulmonary function was weak, with an estimated mean reduction of 1.0% in FEF25-75 associated with dampness and 1.6% with molds. We conclude that dampness in the home is common in many areas of the United States and that home dampness is a strong predictor of symptoms of respiratory and other illness symptoms among 8- to 12-yr-old children.

Asthma↗
PubMed1988

Weak associations in environmental epidemiology.

Several suggestions have been made to enhance study designs to strengthen weak associations. Among these are reduction of non-differential misclassification, and restriction of studies to populations with low underlying risk of disease, due to low exposures to other known determinants of the health effect under investigation. To some extent, these suggestions have been put to use in environmental epidemiology, and in this paper, some prospects and problems associated with these attempts are discussed using examples from our own research.

Air Pollutants↗
PubMed1987

A method for estimating soil ingestion by children.

In recent years, many cases of soil pollution have been unearthed in the Netherlands. The ingestion of soil particles due to mouthing behaviour of young children is an important potential pathway of exposure and may constitute a health risk. For an assessment of these health risks, a reliable estimation of the daily inadvertent ingestion of soil particles is necessary. A method to estimate soil ingestion is the use of titanium (Ti), aluminium (Al) and acid insoluble residue (AIR) content of the soil as a tracer. By measuring these tracers in faeces of children and in soil, an estimate can be made of the amount of soil ingested. This method can be used if the following conditions are met: tracer intake by other routes (food) is low and not too variable; tracer absorption from soil in the gastro-intestinal (GI) tract is negligible; tracer concentrations in soil are high and not too variable. A small pilot study was conducted among 18 children visiting a nursery school and 6 hospitalized children without any possibility of soil contact. The results of the pilot study indicate that each tracer is present in faeces in highly variable amounts, but that a combination of these three tracers produces a useful picture of potential soil ingestion. Quantitatively, a difference between the two populations of 55 mg/d, expressed as soil ingestion, was found. Despite the small numbers involved, this difference was statistically significant as the population standard deviations were small. In a number of different soil types, tracer concentrations were found to be almost equal. Further studies are planned to test the validity of the assumptions, and to investigate larger child populations living in different circumstances.

Administration, Oral↗
PubMed1987

Hydroxyproline excretion in schoolchildren and its relationship to measures of indoor air pollution.

The urinary hydroxyproline excretion was investigated in a population of 6- to 9-year-old schoolchildren living in the Netherlands. Early morning samples of urine were collected at the end of a week in which personal and home monitoring for nitrogen dioxide (NO2) was carried out, and in which detailed information on gas appliances and on parental smoking habits was gathered. In addition, the pulmonary function of the children was measured, and their respiratory symptoms were collected using a standardized questionnaire which was completed by the parents. The hydroxyproline concentrations were standardized for urinary creatinine content. The hydroxyproline/creatinine ratio (HOP/C ratio) was found to be unrelated to NO2 exposure. The presence of major NO2-sources in the kitchen, vented and unvented gas-fired waterheaters, was significantly associated with elevated HOP/C ratios, due to a negative relationship with the creatinine concentration. There was a tendency for HOP/C to increase with the amount of tobacco smoked in the presence of a child. Respiratory symptoms and pulmonary function were unrelated to HOP/C. In this population, the urinary HOP/C ratio was not found to be a close correlate of exposure to NO2 or tobacco smoke, and of respiratory symptoms and pulmonary function.

Air Pollutants↗
PubMed1987

Variability of exposure measurements in environmental epidemiology.

In studies in environmental epidemiology, exposure to harmful agents is often highly variable in time and space. It is not usually possible to measure the relevant, personal exposure of study subjects to these agents directly. Instead, exposure measurements are performed at fixed sites and/or for limited periods of time in many cases. Such measurements are imperfect in the sense that they only approximate the "true" personal exposure of study subjects. When measures of exposure are highly variable in time and space, single measurements approximate the true exposure only to a limited extent. The variability of measures of exposure can be investigated by repetition of the measurements in time and space. Analysis of variance techniques can be used to separate the within-subject or "error" variance from the between-subjects or true variance. Computation of the ratio between the error variance and the true variance is a useful technique to evaluate the potential bias in correlation and regression coefficients calculated with these measures of exposure. Using data from a number of different studies, the authors have estimated the variance ratio of lead exposure and nitrogen dioxide exposure variables. The results suggest that these ratios may be large. Empirical illustrations are given of bias in regression coefficients of childhood blood levels on different lead exposure variables. It is recommended that pilot studies be performed more routinely to estimate the magnitude of the variance ratios of exposure variables of interest in studies in environmental epidemiology.

Adolescent↗