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PubMed1996

The dust content, dust generation, ammonia production, and absorption properties of three different rodent bedding types.

Vermiculite, pine shavings and unbleached eucalyptus pulp contact bedding were compared for dust content, dust production (as a result of animal activity), moisture absorption properties and ammonia production. The percentage of dust particles <300 microm found in pine shavings and vermiculite was 18 and 8 times greater respectively than was found in eucalyptus pulp. The lowest ammonia levels (<1-1 ppm), measured on day 7, were obtained using eucalyptus pulp. Although the ammonia levels obtained for vermiculite compared very well with those of pulp, high levels of dust, up to 5 times more than pulp, were experienced with vermiculite. Pine shavings were associated with the highest ammonia concentration (1-3 ppm), but produced approximately 50% less dust than vermiculite. The water absorption properties obtained for pulp were between 35% and 76% higher than those obtained for vermiculite and pine shavings respectively.

Aluminum Silicates↗
PubMed1983

[Bronchopulmonary diseases due to ultra-hard metal dust, with special reference to the result of the dust analysis].

In order to clarify the relationship between exposure to hard metal dust containing cobalt and bronchopulmonary diseases, cross-sectional medical and occupational hygienic investigations were conducted in a hard metal tool manufacturing factory. As a part of the environmental investigation, general air concentrations and personal exposure to both total dust and cobalt dust were measured. The highest total dust and cobalt concentrations in general atmosphere and personal samples were found in a powder handling room among all departments. The highest personal exposure concentration of cobalt was 1.29 mg/m3 (arithmetic mean value) in the dry grinder using diamond wheels. Powder handlers were exposed to cobalt 0.56 mg/m3, press operators to 0.66 mg/m3, shapers to 0.19 mg/m3, wet grinders to 0.07 mg/m3, and sintering workers to 0.03 mg/m3. In Japan TLV for cobalt has not yet been established. Dust exposure measurement should be carried out in all hard metal industries. TLV for cobalt is discussed by means of literature.

Air Pollutants, Occupational↗
PubMed1984

Acute bronchoconstriction induced by cotton dust: dose-related responses to endotoxin and other dust factors.

Fifty-four healthy humans, selected for their acute airway responsiveness to cotton dust, had spirometric tests immediately before and after 6 hours of exposure to card-generated cotton dust from seven different cottons (of several grades and growing regions). During exposures, we measured airborne concentrations of viable fungi and bacteria (total and gram negative), vertically elutriated gravimetric dust, and vertically elutriated endotoxin. Correlation between each of these five exposure indices and exposure-related acute changes in forced expiratory volume in 1 s showed a statistically significant relationship between all of the indices except concentration of viable fungi. Of the other four indices, endotoxin was the most highly correlated (r = -0.94; p less than 0.00001), and gravimetric dust was the least correlated (r = -0.34; p less than 0.05). These findings suggest that gram-negative endotoxin may play a major role in the acute pulmonary response to inhaled cotton dust.

Adolescent↗
PubMed1990

House dust mites and atopic dermatitis. A case-control study on the significance of house dust mites as etiologic allergens in atopic dermatitis.

The occurrence of house dust mites was measured in homes of 24 patients with atopic dermatitis, 30 patients with mite-sensitive asthma and 32 patients with asthma not related to house dust mites. Patients with mite-positive asthma and patients with atopic dermatitis had significantly higher exposure to house dust mites compared with patients with mite-negative asthma. For atopic dermatitis the higher exposure to house dust mites corresponded to a relative risk of 4.7 and a clear dose-response relationship was demonstrated between exposure and risk of disease in the subgroups of patients with atopic dermatitis. The present epidemiologic results support the idea that house dust mites may be an etiologic factor in a proportion of adult patients with atopic dermatitis.

Allergens↗
PubMed1989

[Dust deposition and elimination in the lung of rats inhaling coal and coalstone dusts].

The deposition and elimination of dust particles from the lung are very important in the occurrence of pneumoconiosis. Two samples of coal mine dusts were examined for their deposition and elimination from the rat lung. In the present study the phagocytic activity of alveolar macrophages in the transport of inhaled dust particles was determined with the method of luminol enhanced chemiluminescence. Coalstone dust was cleared from the alveolar lumen via the tracheobronchial tree more quickly than coal dust.

Animals↗
PubMed1977

[The importance of house dust mites and stored food mites as house dust allergens in the rural population].

House dust samples from rural districts contain more mite species (in particular stored food mites) than samples from urban areas, and the total number of mites is also approximately three times greater. 77 patients from rural districts, 48 of whom allergic to their own house dust, and 29 controls, were tested with mite extracts from Dermatophagoides pteronyssimus, D. farinae, Chortoglyphus arcuatus, Acarus siro, Glycyphagus destructor and Tyrophagus putrescentiae, and a house dust extract. Out of 32 patients who showed positive scratch tests to one or more mite extracts, 29 (90,6 percent) reacted positively to D. pteronyssimus, 25 (78.1 percent) to D. farinae and from 7 to 12 (20-40 percent) to the stored food mites. Out of the 48 patients allergic to their own house dust, 27 (56.2 percent showed positive reactions to D. pteronyssinus, 24 (50.0 percent) to the house dust extract and 21 (43.7 percent) to D. farinae. Only 5 (17.2 percent) out of the 29 controls reacted positively to one or more of the solutions tested. The stored food mites showed 2.5 to 4.5 times more positive reactions in the rural patients compared with the results obtained in urban patients. The importance of these mites in the sensitization of patients from rural districts is discussed.

Adolescent↗
PubMed1976

House dust mite and house dust allergy.

Skin testing and the radioallergosorbent test (RAST) with extracts of house dust and mite (D. farinae) were performed on 100 patients. Correlation between positive prick tests with the two antigens was low, many more reactions being obtained with the house dust antigen in patients clinically positive to house dust. Also, for both antigens, the degree of reactivity was higher with the prick test than with RAST. It is concluded that, in this geographic area, house dust extract is more suitable than mite extract for skin testing and, by inference, for hyposensitization therapy of house dust-sensitive patients.

Adolescent↗
PubMed2003

Providing dust mite-proof covers improves adherence to dust mite control measures in children with mite allergy and asthma.

INTRODUCTION: The most critical dust mite avoidance technique for asthmatic children with mite allergy is the use of dust mite-proof bedding covers. Adherence to allergen control measures is poor due to cost. The purpose of this study was to determine whether giving families mite-proof bedding encasings at the time of the diagnosis with mite allergy would improve adherence at a home visit 2 months later. METHODS: Parents of children (mean age 7.7 years) with asthma and positive skin tests for dust mite were assigned either to an intervention group, which received dust mite covers upon enrollment or a comparison group, which did not. Both groups were instructed in dust mite control measures by a medical provider and told to invest in the covers as part of standard care. Two months after enrollment, parent report and observational measures from each family were obtained during a home visit. RESULTS: The group provided allergen encasings was found to be significantly more likely to have used the casings at the home visit, t(22) = 2.77, P < 0.05. There were no differences between groups in adherence to other mite control strategies. Parenting stress was significantly related to poorer mite control compliance. The most common reason reported for nonadherence to control measures was cost. CONCLUSIONS: Providing mite bedding encasings at the time of diagnosis significantly increases compliance at a 2-month home visit. Medicaid and insurance companies should be encouraged to pay for casings as a cost effective measure to improve asthma care in children with mite allergy.

Adolescent↗
PubMed2006

Permanence of diced cartilage, bone dust and diced cartilage/bone dust mixture in experimental design in twelve weeks.

Bone dust and diced cartilage are used for contour restoration because their minimal donor site morbidity. The purpose of this study is to investigate permanence of bone dust, diced cartilage and bone dust/diced cartilage mixture in rabbits over 12 weeks. New Zealand white rabbits were used for this study. There were three groups in the study: Group I: 1 mL bone dust. Group II: 1 mL diced cartilage. Group III: 0.5 mL bone dust + 0.5 mL diced cartilage mixture. They were placed into subcutaneous tissue of rabbits and removed 12 weeks later. The mean volumes of groups were 0.23 +/- 0.08 mL in group I, 0.60 +/- 0.12 mL in group II and 0.36 +/- 0.10 mL in group III. The differences between groups were found statistically significant. In conclusion, diced cartilage was found more reliable than bone dust aspect of preserving its volume for a long period in this study.

Animals↗
PubMed2006

Protective effect of the DNA vaccine encoding the major house dust mite allergens on allergic inflammation in the murine model of house dust mite allergy.

BACKGROUND: Vaccination with naked DNA encoding antigen induces cellular and humoral immunity characterized by the activation of specific Th1 cells. OBJECTIVE: To evaluate the effects of vaccination with mixed naked DNA plasmids encoding Der p 1, Der p 2, Der p 3, Der f 1, Der f 2, and Der f 3, the major house dust mite allergens on the allergic inflammation to the whole house dust mites (HDM) crude extract. METHODS: Three hundred micrograms of these gene mixtures were injected into muscle of BALB/c mice. Control mice were injected with the pcDNA 3.1 blank vector. After 3 weeks, the mice were actively sensitized and inhaled with the whole house dust mite extract intranasally. RESULTS: The vaccinated mice showed a significantly decreased synthesis of total and HDM-specific IgE compared with controls. Analysis of the cytokine profile of lymphocytes after challenge with HDM crude extract revealed that mRNA expression of interferon-gamma was higher in the vaccinated mice than in the controls. Reduced infiltration of inflammatory cells and the prominent infiltration of CD8+ T cells were observed in histology of lung tissue from the vaccinated mice. CONCLUSION: Vaccination with DNA encoding the major house dust mite allergens provides a promising approach for treating allergic responses to whole house dust mite allergens.

Journal Article↗
PubMed1987

Monoclonal immunoassays for major dust mite (Dermatophagoides) allergens, Der p I and Der f I, and quantitative analysis of the allergen content of mite and house dust extracts.

Monoclonal, two-site radioimmunoassays (RIAs) were developed to measure allergen Der p I of Dermatophagoides pteronyssinus or Der f I of D. farinae. Microtiter plates coated with monoclonal antibody (Mab) were incubated with mite extract, and bound allergen was detected with a second 125I-labeled Mab of different epitope specificity. The Mab RIAs were very sensitive (nanogram range) and highly specific. D. pteronyssinus extracts with different concentrations of Der p I demonstrated parallel binding curves, whereas a potent D. farinae extract demonstrated less than 5% of the Der p I binding in the same assay. Similar parallel curves were obtained with several D. farinae extracts in the Der f I assay, whereas D. pteronyssinus extract demonstrated little or no binding. The Mab RIAs were compared with an inhibition RIA that measured cross-reacting determinants on both Der p I and Der f I (antigen P1 equivalent [AgP1Eq]). The results demonstrated good quantitative agreement between these assays in commercial mite and house dust extracts (mean difference 1.57 +/- 0.5-fold). Thirty house dust samples with known mite counts, Der p I, and AgP1Eq content were also compared. The summed Mab RIA values for Der p I and Der f I demonstrated a very good correlation with AgP1Eq values (r = 0.86; p less than 0.001) and with assessments of total mite-allergen content by RAST inhibition (n = 21, r = 0.77; p less than 0.001). Furthermore, in samples with more than 10 mites per 100 mg of dust, the Der p I: Der f I ratio closely correlated with the ratio of the two mites counted by microscopy (n = 15, r = 0.89; p less than 0.001). The Mab RIAs can measure allergen levels in mite or dust extracts without the need for purified allergen or affinity-purified antibodies and can readily be standardized. These assays will be useful in epidemiologic studies of allergic asthma, to assess patients' exposure to mite allergens, and the effects of avoidance regimens. Because of the long-term stability and reproducibility of the reagents, Mab-based assays for specific allergens will also play an important role in the standardization of mite and other allergen extracts.

Allergens↗
PubMed1987

Cat allergen content of commercial house dust extracts: comparison with dust extracts from cat-containing environment.

Eighteen lots of house dust extract from nine commercial sources (obtained as weight per volume or protein nitrogen unit per cubic centimeter) were analyzed for cat allergen content by direct quantitative immunoelectrophoresis after concentration. Cat allergen 1 was measurable (greater than 0.3 units) in 11 extracts with a mean (range) of 5.8 (1.3 to 31.0) U/gm of source material. Cat albumin was measurable (greater than 2.4 units) in 12 extracts with a mean (range) of 53.4 (11.5 to 319.7) U/gm. In order to evaluate whether the cat allergen 1 content is a significant contribution to the allergenic activity of the extract, 17 cat-allergic subjects were tested by prick test with a purified preparation of cat allergen 1. The mean (range) concentration that produced a 3 mm wheal was 0.01 (0.0013 to 1.33) U/ml. Therefore, the commercial house dust extracts studied, when these extracts were diluted to a concentration commonly used for prick testing, would frequently contain enough cat allergen 1 to produce strong prick test reactions in cat-allergic subjects. It is difficult to justify the use of such commercial dust extracts as diagnostic reagents. For comparison purposes, nine dust samples from an apartment housing two cats were similarly analyzed. Cat allergen 1 was measurable in seven samples with a mean (range) of 23.8 (1.8 to 64.3) U/gm. Cat albumin could be measured in all nine samples with a mean (range) of 32.3 (0.16 to 70.8) U/gm. The average amount of cat allergen 1 that could be washed off the surface of the cats was 270 units. Large reservoirs of cat allergen 1 were present.(ABSTRACT TRUNCATED AT 250 WORDS)

Allergens↗
PubMed1993

Allergens in school dust. I. The amount of the major cat (Fel d I) and dog (Can f I) allergens in dust from Swedish schools is high enough to probably cause perennial symptoms in most children with asthma who are sensitized to cat and dog.

BACKGROUND: We investigated the levels of Fel d I and Can f I in dust from tables, chairs, and floors in 29 classrooms in four Swedish schools. METHODS: School authorities were questioned about building characteristics, students were interviewed about their health and exposure to animals, and cleaning personnel were asked about methods and frequency of cleaning. Dust samples were taken from floors and horizontal surfaces of chairs and tables in all classrooms during a 6-week period. RESULTS: Higher amounts of Fel d I were found on chairs (geometric mean, 953 ng per gram of dust) than on tables (525 ng/gm) and floors (134 ng/gm). The concentration of Can f I (5.3 ng/gm) on chairs was 2 to 20 times higher than Fel d I. The concentration of Can f I (200 ng/gm) in dust from floors was twice as high as that of Fel d I. The concentration of Can f I on chairs was within the range previously found by other investigators in houses with dogs. CONCLUSIONS: Since the levels of both Fel d I and Can f I were much higher on chairs than on floors, we hypothesize that allergen is brought to schools on the clothes of students and teachers. We conclude that the levels of the two major allergens from furred pets (i.e., Fel d I and Can f I) in Swedish schools are probably high enough to sensitize children and to induce asthma in most children who are allergic to cats or dogs.

Adult↗
PubMed2000

Tantalum dust deflagration in a bag filter dust-collecting device.

An accidental tantalum powder deflagration with casualties occurred during the operation of a bag filter dust-collecting device. To understand the mechanism of the incident and its material hazards, experiments for determining the combustibility and ignition characteristics of the tantalum powder were performed. The magnitude of the tantalum dust explosion is classified as severe (K(st)=273), contrary to the classification found in the preceding literature. The minimum ignition energies for both a dust cloud and a dust layer of the tantalum powder were also found to be far lower than previous values. Judging from the observation of the surface with an SEM, the coral-like structure of each particle of the tantalum powder can enhance its fire and explosion hazards and affect its sensitivity to electrostatic sparks by increasing in particle surface area. A thin, non-conductive oxide layer of the tantalum powder surface has a high resistivity and generates electrostatic charge when rubbed with conductive materials like the wall of the collecting device. The authors conclude that the possible cause of the ignition was electrostatic discharge resulting from charging electrostatically.

Accidents, Occupational↗
PubMed1975

Effect of the 2.0 mg/m3 coal mine dust standard on underground environmental dust levels.

The 1969 Federal Coal Mine Health and Safety Act established environmental dust standards for underground coal mines. The Act requires that the average concentration of respirable dust in the active workings of a mine be maintained at or below 3.0 mg/m3; and, that effective December 30, 1972, the 3.0 mg/m3 standard be reduced to 2.0 mg/m3. This paper discusses the current status of dust levels in our underground coal mines, the effect of the 2.0 mg/m3 standard on underground dust levels, and associates the current levels with specific operations and occupations. The comparison is made between current levels and those existing prior to December 30, 1972.

Coal Mining↗
PubMed1978

Identification and prevalence of culturable mesophilic microfungi in house dust from 100 Danish homes. Comparison between airborne and dust-bound fungi.

In order to encircle possible allergen sources, fungi from house dust were cultivated and identified. Dust from vacuum cleaners was inoculated on Petri dishes containing V-8 agar with addition of penicillin and streptomycin to eliminate the bacterial flora. The number of genera identified were for the most part consistent with the genera trapped from the air. However, presumably owing to their dispersal biology it was demonstrated that members of Mucorales were much more frequently represented in the samples obtained by this method compared with gravimetric and volumetric measurements. The method is recommended as a simple way to demonstrate and identify the mould contents in house dust and as a tool for the identification of some of the real allergenic sources in house dust.

Air Microbiology↗
PubMed2005

Concentrations of cat and dust-mite allergens in dust samples from 92 large US office buildings from the BASE Study.

UNLABELLED: The concentrations of cat (Fel d1) and dust-mite (Der f1 and Der p1) allergens were measured in 92 large office buildings in the US Environmental Protection Agency's Building Assessment Survey and Evaluation (BASE) Study (251 dust samples; one to four samples per building). Fel d1 was detected in almost all buildings and samples (91 buildings, 99%; 235 samples, 94%; range: <0.01-19 microg/g; median: 0.3 microg/g). Cat allergen exceeded 1 microg/g (a lower symptom threshold) in 56 samples (22%) from 45 buildings, but exceeded 8 microg/g (a sensitization threshold) in only two samples (1%) from two buildings. Der f1 or Der p1 was found in approximately half of all buildings and samples (63 and 70% of buildings; 45 and 51% of samples; range: <0.01-53 microg/g and <0.01-25 microg/g; median: <0.02 and 0.03 microg/g, respectively). Mite allergen exceeded 2 microg/g (a sensitization threshold) in seven samples (3%) from five buildings and exceeded 10 microg/g (a symptom threshold) in three samples (1%) from three buildings. Fel d1 concentration was significantly higher in samples collected in summer (June to September, 48 buildings), but cat allergen was not correlated with either mite allergen. Der f1, but not Der p1, concentration tended to be higher in samples collected in winter (December to April, 44 buildings), and the two mite allergens were significantly correlated only in winter. Cat and mite allergens were detected in 78% of representative US office buildings, but the concentrations seldom exceeded levels associated with sensitization or symptom provocation. PRACTICAL IMPLICATIONS: The information on the concentrations of cat and dust-mite allergens in representative large US offices has expanded the baseline data available for interpretation of measurements from other building investigations. With suggested refinements, the BASE protocol for measurement of allergen concentrations in dust samples may serve as a guide to future studies of building characteristics, bioaerosol concentrations, and occupant perceptions of the indoor environment.

Air Microbiology↗
PubMed1996

Mineral dusts cause elastin and collagen breakdown in the rat lung: a potential mechanism of dust-induced emphysema.

It is now accepted that workers with exposure to mineral dusts can develop airflow obstruction. The basis of this process is uncertain, but carefully performed morphologic studies suggest that coal, silica, and perhaps other dusts may produce emphysema in humans. To investigate the mechanisms involved in this process, we administered crystalline silica (quartz) or titanium dioxide (rutile) to rats in a single intratracheal instillation. At varying times after instillation, the animals' lungs were lavaged, the lavageate from one lung was dried and hydrolyzed, and the amounts of desmosine (DES),as a measure of elastin breakdown, and hydroxyproline (HP), as a measure of collagen breakdown, were determined. The lavageate from the other lung was counted for inflammatory cells. Both silica and titanium dioxide caused a dose-dependent increase in DES and HP 24 h after instillation. When an equivalent dose (30 mg) of silica or rutile was administered and animals were sacrificed at various times up to 21 d, a sustained increase in lavage DES and HP was seen in the silica-treated animals, and this was accompanied by a sustained increase in polymorphonuclear leukocytes (PMN); in contrast, both lavage PMN and lavage DES/HP rapidly peaked and then declined in the titanium dioxide-treated animals. Numbers of macrophages remained elevated over the 21-d period of sacrifice with both types of treatment. These data show for the first time that mineral dusts can cause connective-tissue breakdown in the lung, with the release of matrix components into the alveolar spaces. The amount of connective-tissue breakdown appears to parallel the number of PMN but not the number of macrophages in the alveolar spaces, suggesting that PMN-derived proteolytic enzymes are responsible for the breakdown. This process probably plays a role in dust-induced emphysema.

Animals↗