PubMed Health⌕ Search

Biomedical subjects

J Douwes

Publications and source records attributed to J Douwes.

At least 37 records · Page 2Linked to original sources
PubMed2002

Allergens and endotoxin on mothers' mattresses and total immunoglobulin E in cord blood of neonates.

The current authors examined whether mite and cat allergen and bacterial endotoxin levels in dust of the mothers' mattresses were associated with cord blood immunoglobulin (Ig)E (CB-IgE) levels in newborns. Data from 1,332 term and normal weight neonates, from an ongoing birth cohort study, influences of life-style related factors on the immune system and the development of allergies in childhood (LISA), with complete information on exposure to biocontaminants in mattress dust and CB-IgE were analysed. Two thirds of CB-IgE were undetectable (<0.35 kU x L(-1)). Thus, 0.35 and 0.45 kU x L(-1) (4th quartile) were chosen as cut-offs. Nonparametric smoothing (generalised additive models) showed statistically significant confounder-adjusted associations between elevated CB-IgE levels (> or = 0.45 kU x L(-1)) and log-transformed exposures to cat (linear), mite (inverse u-shaped), and endotoxin (u-shaped). After adjustment for covariables, elevated CB-IgE levels (logistic regression using the 1st-4th quartiles of exposure) were positively associated with high cat-allergen exposure and medium exposure to mite allergen, but were inversely associated with exposure to endotoxin. The associations were similar, but somewhat weaker, when 0.35 kU x L(-1) was used as cut-off. These results, showing an association between prenatal allergen and endotoxin exposures and immunoglobulin E production, suggest that the development of foetal immune responses may be affected.

Allergens↗
PubMed2001

Asthma and other respiratory symptoms in New Zealand pine processing sawmill workers.

BACKGROUND: To study respiratory symptoms in pine sawmill workers. METHODS: A respiratory health questionnaire was administered to 772 pine sawmill workers and the association between symptoms and job-title-based exposure was studied. RESULTS: Asthma in exposed workers (18%, n = 704) was more common than in the general population (12.1%, n = 592; adjusted OR (95% CI): 1.6 (1.1-2.3)). Asthma was also more common in the low exposure group (15.6%, n = 294) and high exposure groups (high exposure to 'green dust'; 20.4%, n = 212 and high exposure to 'dry dust'; 18.8%, n = 198) than in the non-exposed workers (9.2%, n = 65). Adjusted odds ratios were 1.9 (0.7-4.9), 2.7 (0.9-7.6), and 2.1 (0.8-5.7), respectively. Adjusted odds ratios for symptoms of cough were 2.7 (1.2-6.5) for the low, 5.2 (2.1-13.0) for the high 'green dust' and 3.3 (1.4-7.9) for the high 'dry dust' exposure groups. Moreover, eye and nose irritations were significantly more prevalent in the high and low exposure groups. CONCLUSIONS: Working in pine sawmilling is associated with an increased prevalence of asthma and cough symptoms and eye and nose irritation.

Adult↗
PubMed2001

Fungal extracellular polysaccharides, beta (1-->3)-glucans and culturable fungi in repeated sampling of house dust.

Fungal exposure inside homes has been associated with adverse respiratory symptoms in children and adults. While fungal assessment has traditionally relied upon questionnaires, fungal growth on culture plates and spore counts, new immunoassays for extracellular polysaccharides (EPS) and beta (1-->3)-glucans have enabled quantitation of fungal agents in house dust in a more timely and cost-effective manner, possibly providing a better measure of fungal exposure. We investigated associations among measurements of EPS, beta (1-->3)-glucans and culturable fungi obtained from 23 Dutch homes. From each home, dust samples were vacuumed from the living room floor twice during the Fall, Winter and Spring seasons for a total of six collections (every 6 weeks from October 1997 to May 1998). Samples were sieved and fine dust was analyzed for EPS from Aspergillus and Penicillium spp. combined, beta (1-->3)-glucans and culturable fungi. EPS was positively associated with glucan; an increase from the 25th to the 75th percentile of glucan concentration was associated with a 1.6-fold increase in EPS concentration (95% CI = 1.3 to 2.0; p < 0.01). The most significant variables associated with EPS and glucan concentrations were the surface type that was vacuumed and the concentration of total culturable fungi (in colony forming units (CFU)/g dust), with an increase in CFU/g from the 25th to the 75th percentile associated with a 1.3 (1.1-1.6)-fold increase in glucan and a 1.7 (1.3-2.2)-fold increase in EPS concentrations. In addition, the within-home variation of EPS levels were smaller than those between homes (25,646 U/g vs. 50,635 U/g), whereas the variation of glucan levels was similar within and between homes (1,300 vs. 1,205 micrograms/g). These positive associations suggest that house dust concentrations of beta (1-->3)-glucan, and particularly those of EPS, are good markers for the overall levels of fungal concentrations in floor dust which is a surrogate for estimating airborne fungal exposure.

Adult↗
PubMed2001

Pets and vermin are associated with high endotoxin levels in house dust.

BACKGROUND: Previous studies have shown that the risk for allergic sensitization is lower in children who grew up on farms and in young adults who were exposed to dogs in early childhood. A higher microbial exposure in general and in particular to endotoxin in early childhood might contribute to this lower risk of atopy. OBJECTIVE: We examined whether the presence of pets or vermin in the home is associated with higher endotoxin concentrations in settled house dust. METHODS: House dust was sampled in a standardized manner on the living room floors of 454 homes of German children aged 5-10 years (participation rate 61%). Endotoxin was assessed with a quantitative kinetic chromogenic Limulus Amebocyte Lysate (LAL) method. Associations between endotoxin levels, pets and vermin are presented as ratios of the crude and confounder adjusted geometric means (means ratios) in the category of study vs. a reference category using multiple linear regression models. RESULTS: Endotoxin concentrations in living room floor dust sampled in homes without pets and vermin were lower (1246 ng per square meter, 1519 ng endotoxin/g dust, n = 157) than those sampled in homes with pets or vermin (2267 ng per square meter, 2200 ng endotoxin/g dust, n = 296). After adjustment for city of residence, season of dust sampling, age of the building and story of the dwelling, means ratios for endotoxin expressed per gram of dust were statistically significantly increased for dog (1.64, 95% CI 1.09-2.46), for cat (1.50, 95% CI 1.03-2.18) and for cockroach (3.01, 95% CI 1.37-6.60), whereas no major statistically significant associations were found for other pets, ants and mice. CONCLUSION: Keeping a dog or a cat in the home is consistent with higher exposure to endotoxin and might therefore contribute to the lower risk of atopy in later life.

Air Pollution, Indoor↗
PubMed2001

Short term exposure to airborne microbial agents during farm work: exposure-response relations with eye and respiratory symptoms.

OBJECTIVES: Exposure to high levels of non-infectious microbial agents is recognised as a cause of respiratory disease in working populations, but except for endotoxins, little is known about exposure-response relations. As these effects do not depend on viability, exposure to non-viable microbial agents is important. Various methods not based on microbial cultures were explored to study the complex microbial exposure of farmers and associations with acute symptoms during work. METHODS: Airborne exposure was measured when farmers carried out specific tasks. Fungal spores, bacteria, endotoxins, beta(1-->3)-glucans, fungal antigens specific for Penicillium and Aspergillus species, and mites were measured by methods not based on microbial cultures. Also silica, inorganic and organic dust, ammonia, hydrogen sulphide, and nitrogen dioxide were measured. Respiratory, and nose and eye symptoms experienced during measurements were recorded by a short questionnaire. Both univariate and multivariate statistical analyses were applied to assess the relations between exposure and acute symptoms. RESULTS: 106 Farmers and their spouses participated in this study. Prevalences of work related symptoms were: wheezing 3%; chest tightness 7%; cough 14%; eye symptoms 18%; and nose symptoms 22%. Prevalence ratios for nose and eye symptoms were 4-8 after exposure to 20-500x10(3) fungal spores/m(3) and higher, and a prevalence ratio for cough was 4 after exposure to 500-17,000x10(3) fungal spores/m(3). Nose symptoms were also associated with exposure to silica with prevalence ratios of 4-6 after exposure to 0.015-0.075 mg /m(3) and higher. CONCLUSIONS: Farmers had a high occurrence of symptoms of the nose and eyes as well as cough during work. These symptoms were associated in a dose dependent manner with exposure to fungal spores. Nose symptoms were also associated with exposure to silica.

Aged↗
PubMed2001

Beta(1-->3)-glucan in house dust of German homes: housing characteristics, occupant behavior, and relations with endotoxins, allergens, and molds.

beta(1-->3)-Glucans are potent proinflammatory agents that have been suggested to play a role in indoor-related respiratory health effects. The aim of this study was to assess whether beta(1-->3)-glucan concentrations in house dust are correlated with levels of endotoxins, allergens, and culturable mold spore counts in house dust. Further, the associations of beta(1-->3)-glucan with housing characteristics and occupant behavior were assessed. beta(1-->3)-Glucan was measured in settled house dust from living room floors of 395 homes of two German cities, Erfurt and Hamburg, with a specific enzyme immunoassay. Concentrations ranged from below the limit of detection to 19,013 microg/m(2) (22,588 microg/g dust). Concentrations per square meter were found to be correlated with endotoxins, mite and cat allergens, and culturable mold spores. Correlations were weaker when concentrations were expressed per gram of dust, indicating that variance in concentrations of all factors is largely determined by the amount of dust sampled. Associations between beta(1-->3)-glucan, housing characteristics, and occupant behavior were found for concentrations per square meter but not for concentrations per gram of dust. The following characteristics were associated with a significant increase in beta(1-->3)-glucan levels: carpets in the living room [means ratio (MR) = 1.9-2.1], keeping a dog inside (MR = 1.4), use of the home by four or more persons (MR = 1.4), use of the living room for > 180 hr/week (MR = 2.1), lower frequency of vacuum cleaning (MR = 1.6-3.0) and dust cleaning (MR = 1.2 and 1.4, respectively), and presence of mold spots during the past 12 months (MR = 1.4). We conclude that that the amount of dust sampled can be used as a proxy for hygiene and that beta(1-->3)-glucan concentrations per square meter are related to the amount of dust sampled.

Air Pollution, Indoor↗
PubMed2001

Work-related symptoms in sewage treatment workers.

The aim of this study was to investigate health symptoms in sewage treatment workers. A health questionnaire was distributed among 147 sewage treatment workers. Correlating symptoms were clustered using principal component analysis and the association with self-reported exposure was assessed by calculating prevalence odds ratios (OR). Endotoxin was measured in two treatment plants. Personal endotoxin exposure was low (<10 Endotoxin Units/m(3)). Factor analysis of 29 symptoms resulted in four clusters of highly correlating symptoms: 'flu-like symptoms'; 'higher airway symptoms'; 'lower airway symptoms'; and 'neurological symptoms'. These clusters were positively associated with working with sewage, but only significant for 'flu- like symptoms' (OR=5.0; 95%CI=1.4-17.6; p<0.05) and 'neurological symptoms' (OR=4.2; 95%CI=1.5-11.7; p<0.01). Chemical exposure was associated with 'neurological symptoms' (OR=8.4; 95%CI=1.1-65.7; p<0.05). The use of daily washed working clothes was negatively associated with 'flu-like symptoms' (OR=0.3; 95%CI=0.1-0.6; p<0.01). In conclusion, sewage treatment workers develop a large variety of work-related symptoms that are not likely caused by endotoxin exposure only. Good hygienic practice at the workplace may prevent some of these symptoms

Adult↗
PubMed2000

Upper airway inflammation assessed by nasal lavage in compost workers: A relation with bio-aerosol exposure.

BACKGROUND: Exposure to microbial agents in the composting industry may cause work related airway inflammation. Nasal lavage (NAL) has been proposed as a noninvasive method to assess such effects in population studies. METHODS: Pre- and post-shift NAL were performed in the workers of a compost plant visited in 1995 (n = 14) and 1996 (n=15), of whom only four participated in both surveys. Total cells, cytokines and other inflammation markers were measured in NAL fluid, and pre-shift levels and post/pre concentration ratios were compared with NAL results obtained in the same periods in 10 and 9 controls, respectively, and with levels of airborne exposure to microbial agents endotoxin and beta(1,3)-glucan as measured in personal air samples. RESULTS: Job-title specific exposure levels in the first survey ranged from 75 to 527 EU/m(3) for endotoxin and from 0.54 to 4.85 microg/m(3) for beta(1,3)-glucan. In the second survey these values were lower, 29-285 EU/m(3) and 0.36-4.44 microg/m(3), respectively. In the first survey pre-shift NAL concentrations of total cells, MPO, IL-8, NO and albumin were significantly (1.1-4.8 fold) higher in compost workers than in controls. Post/pre ratios for various markers were significantly (1.2-3.2 fold) higher in compost workers in both surveys. NAL cells were mainly neutrophils, while eosinophils were only incidentally observed. A weak relation with exposure was found for pre-shift levels of MPO, uric acid and urea in the first survey. CONCLUSIONS: Occupational exposure of compost workers may cause acute and possibly (sub-)chronic inflammatory reactions in the upper airways, presumably induced by non-allergenic pro-inflammatory agents like endotoxins and beta(1, 3)-glucans.

Adult↗
PubMed2000

Worker exposures to airborne dust, endotoxin and beta(1,3)-glucan in two New Zealand sawmills.

BACKGROUND: Sawmill workers have an increased risk of developing occupational asthma and other respiratory symptoms. Wood dust and microorganisms have both been suggested to play a role, but few studies have measured microbial exposure levels in sawmills. METHODS: The preliminary study reported in this paper assessed airborne dust, bacterial endotoxin and beta(1,3)-glucan levels in 37 samples from two New Zealand sawmills. RESULTS: Nearly one-third of the measured dust levels exceeded 1 mg/m(3) and only one sample exceeded the legal limit of 5 mg/m(3). Endotoxin levels were clearly elevated with 50% of all measured exposures above 50 EU/m(3) (range: 7-588 EU/m(3)). beta(1,3)-glucan levels were comparable with levels measured in other industries where workers are exposed to organic dust. Workers in the planing department had the highest mean exposures to dust, endotoxin and beta(1,3)-glucan. Dust levels were only weakly correlated with endotoxin and beta(1,3)-glucan levels. CONCLUSIONS: Endotoxin exposures in sawmill workers are at levels sufficient to potentially contribute to the development of respiratory symptoms. Moreover, measurement of dust exposure is a poor proxy for beta(1,3)-glucan and endotoxin exposure in sawmill workers.

Dust↗
PubMed2000

Occupational respiratory symptoms in New Zealand hairdressers.

BACKGROUND: A study of occupational respiratory symptoms in hairdressers was carried out in 26 salons in New Zealand. METHODS: A questionnaire was administered to 100 hairdressers and 106 office and shop workers, recording respiratory symptoms, demographic data, and smoking habits. Pulmonary function was measured before each shift. RESULTS: Hairdressers had a higher prevalence of asthma symptoms, diagnosed asthma, and asthma attacks in the previous 12 months, but these differences reduced markedly when adjusted for age, gender and smoking. Hairdressers had a significantly lower pulmonary function, even after adjustment for smoking, but this difference was entirely due to differences between hairdressers and office workers and there were no such differences between hairdressers and shop workers. CONCLUSIONS: The excess symptom prevalence in hairdressers was largely due to the high smoking rates. Mean pulmonary function was lower in hairdressers but this finding requires further study.

Adolescent↗
PubMed2000

Increased levels of markers of microbial exposure in homes with indoor storage of organic household waste.

As part of environmental management policies in Europe, separate collection of organic household waste and nonorganic household waste has become increasingly common. As waste is often stored indoors, this policy might increase microbial exposure in the home environment. In this study we evaluated the association between indoor storage of organic waste and levels of microbial agents in house dust. The levels of bacterial endotoxins, mold beta(1-->3)-glucans, and fungal extracellular polysaccharides (EPS) of Aspergillus and Penicillium species were determined in house dust extracts as markers of microbial exposure. House dust samples were collected in 99 homes in The Netherlands selected on the basis of whether separated organic waste was present in the house. In homes in which separated organic waste was stored indoors for 1 week or more the levels of endotoxin, EPS, and glucan were 3.2-, 7.6-, and 4. 6-fold higher, respectively (all P < 0.05), on both living room and kitchen floors than the levels in homes in which only nonorganic residual waste was stored indoors. Increased levels of endotoxin and EPS were observed, 2.6- and 2.1-fold (P < 0.1), respectively, when separated organic waste was stored indoors for 1 week or less, whereas storage of nonseparated waste indoors had no effect on microbial agent levels (P > 0.2). The presence of textile floor covering was another major determinant of microbial levels (P < 0.05). Our results indicate that increased microbial contaminant levels in homes are associated with indoor storage of separated organic waste. These increased levels might increase the risk of bioaerosol-related respiratory symptoms in susceptible people.

Air Pollution, Indoor↗
PubMed2000

Is allergen exposure the major primary cause of asthma?

In recent decades a number of authors have argued that allergen exposure is the major primary cause of asthma, and that the global increases in asthma prevalence are due to increases in exposure to aeroallergens. We have assessed the epidemiological evidence in support of this hypothesis. No longitudinal studies were identified in which allergen exposure during infancy in a random population sample has been related to asthma risk after the age of six years. Two studies have been conducted in selected populations chosen on the basis of a family history of asthma or allergy; one study found a non-statistically significant association whereas the other study found no association. Many of the identified prevalence studies in children showed negative associations between allergen exposure and current asthma, and the weighted averages of the population attributable risks in children were 4% for Der p 1, 11% for Fel d 1, -4% for Bla g 2, and 6% for Can f 1. There was little change in these estimates in studies in which children whose parents had adopted allergen avoidance measures were excluded. Furthermore, evidence from population studies is equivocal and provides little consistent evidence that allergen exposure is associated with the prevalence of asthma at the population level. Population-based cohort studies are clearly required, but currently available evidence does not indicate that allergen exposure is a major risk factor for the primary causation of asthma in children.

Allergens↗
PubMed2000

(1-->3)-beta-D-glucan and endotoxin in house dust and peak flow variability in children.

House dust-associated bacterial endotoxins have been shown to be associated with asthma severity, and a similar role has been suggested for fungal (1-->3)-beta-D-glucans. In this study the relation between these agents and peak expiratory flow (PEF) variability was investigated in 148 children 7 to 11 yr of age of whom 50% had self- or parent-reported chronic respiratory symptoms. All children self-monitored twice daily their PEF for a period of 16 wk. Dust samples were collected from mattresses and from living room and bedroom floors, and endotoxin and (1-->3)-beta-D-glucan were measured in dust extracts. The relations with mean daily PEF variability (Ampl%mean) were investigated by linear regression analysis, adjusting for dust mite allergen levels, presence of pets, and type of floor cover. In unadjusted analyses the levels of both endotoxin and (1--> 3)-beta-D-glucan per square meter of living room floor were significantly associated with PEF-variability (but not when expressed per gram of sampled dust), particularly in atopic children with asthma symptoms. Adjusted analyses showed the same association for (1--> 3)-beta-D-glucan but not for endotoxin. Although no associations were found with microbial agent levels in bedroom floor or mattress dust, high levels of (1-->3)-beta-D-glucan in living room floor dust apparently increase PEF variability in asthmatic children.

Air Pollution, Indoor↗
PubMed1999

Fungal extracellular polysaccharides in house dust as a marker for exposure to fungi: relations with culturable fungi, reported home dampness, and respiratory symptoms.

BACKGROUND: Epidemiologic studies have demonstrated an association between indoor fungal growth and respiratory symptoms. However, in only a few studies was fungal exposure actually measured. OBJECTIVE: The purpose of this study was to evaluate the measurement by enzyme immunoassay of extracellular polysaccharides of Aspergillus and Penicillium species (EPS-Asp/Pen ) in house dust as a marker for fungal exposure and to study the relations between EPS-Asp/Pen levels and home dampness and respiratory symptoms in children. METHODS: Extracts of house dust samples from bedroom and living room floors and mattresses from homes of 31 children with chronic respiratory symptoms and 29 children with no chronic respiratory symptoms were analyzed for EPS-Asp/Pen. RESULTS: EPS-Asp/Pen were readily detectable (40 to 46,513 nanogram equivalent/g dust) in 161 house dust extracts, with highest concentrations in living room floor dust. EPS-Asp/Pen levels were 2 to 3 times higher on carpeted floors than on smooth floors. EPS-Asp/Pen were significantly correlated with total culturable fungi (r = 0.3 to 0.5) and with house dust mite allergens (r = 0.3 to 0.5). EPS-Asp/Pen levels in living room floor dust were positively associated with occupant-reported home dampness. This was not observed for EPS-Asp/Pen in bedroom floor and mattress dust. EPS-Asp/Pen levels in living room floor dust were positively associated with respiratory symptoms. EPS-Asp/Pen in bedroom floor and mattress dust showed a reversed association with respiratory symptoms, possibly because of allergen-avoidance measures taken in the bedroom. CONCLUSION: The enzyme immunoassay for fungal EPS-Asp/Pen may be a useful method for exposure assessment of indoor fungi.

Antigens, Fungal↗
PubMed1999

Review of methods applicable to the assessment of mold exposure to children.

This article presents discussion of the assessment of the exposure of children to fungi, substances derived from fungi, and the environmental conditions that may lead to exposure. The principles driving investigations of fungal contamination and subsequent exposure are presented as well as guidelines for conducting these investigations. A comprehensive description of available research sampling and analysis techniques is also presented.

Air Pollution, Indoor↗
PubMed1999

Application of the classic Limulus test and the quantitative kinetic chromogenic LAL method for evaluation of endotoxin concentration in indoor air.

The classic (gel-clot procedure) Limulus test (CLT) and the quantitative kinetic chromogenic LAL method (KQCL) used for the evaluation of bacterial endotoxin concentration in the indoor air of dwellings were compared. The scientific procedure included analyses of 40 air samples supplemented by the analysis of 20 sample duplicates (selected at random) which were taken during the fall season from 10 flats located in 3 towns of the Upper Silesian region (southern Poland). The particulate aerosol probes were sampled by Harvard impactor and Casella sampler. The same samples were analyzed in the Netherlands using the quantitative kinetic chromogenic LAL method, and in Poland using the classic Limulus test. Comparison of both methods revealed that the quantitative kinetic chromogenic LAL method was more precise, with better reproducibility (the coefficient of variation between analyses of the main probe and its duplicate was over two times smaller in the KQCL method than in the CLT method), fully automated in the phase of analysis and data reading, and faster and more effective than the classic Limulus test. Nevertheless, on the basis of the obtained results, the usefulness of the classic Limulus method for assessment of the degree of pollution of indoor air with bacterial endotoxin seems to be confirmed as in the majority of examined samples (21 out 40) the results obtained by both methods were of the same order of magnitude, and in the remaining 19 samples did exceed one order of magnitude. Thus, the data received by means of the classic Limulus test may be regarded as acceptable.

Air Microbiology↗
PubMed1998

Acute lung function changes and low endotoxin exposures in the potato processing industry.

Work-related respiratory symptoms, acute lung function changes and personal endotoxin exposure were studied in 61 workers from a potato processing plant. According to their job title mean endotoxin exposure level, workers were divided into low (AM = 21 EU/m3) and high (AM = 56 EU/m3) exposure categories. Shortness of breath and chest tightness during work were reported by 18% and 16% of the workers, respectively, mainly in the low endotoxin exposure category. A total of 148 across-shift lung function changes were measured during three consecutive afternoon shifts. The mean FEV1 and MMEF showed a decrease over the work shift, being largest on the first working day after a 3-day absence from work. Workers exposed to high endotoxin levels showed a larger across-shift decrease in lung function than workers exposed to low endotoxin exposures, the effect being most pronounced on the first day after a 3-day absence from work. At the start of the second work shift, FVC, FEV1 and MMEF were lower than at the start of the first work shift. This difference was larger for high exposed workers. High exposed workers with work-related respiratory symptoms showed an 8-10% across-shift change in FVC, FEV1 and MMEF We conclude that significant across-shift decreases in lung function of potato processing workers is related to endotoxin exposure levels above 53 EU/m3 over 8 hr.

Acute Disease↗