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PubMed1986

Vegetable dust and airway disease: inflammatory mechanisms.

Exposure to cotton or grain dust causes an obstructive bronchitis in certain subjects, mechanisms of which are poorly understood. A difficulty encountered in discerning mechanisms of this airway disease is the lack of knowledge of the active components of these dusts. Clinical features suggest common but not exact mechanisms of the airway disease associated with these vegetable dusts. Human and animal studies show evidence of acellular and cellular inflammatory mechanisms of the bronchoconstriction and inflammation associated with these disorders. Potential cellular sources include alveolar macrophages, polymorphonuclear leukocytes, mast cells, basophils, eosinophils and lymphocytes. Acellular origins include the complement and humoral antibody systems, both of which have been implicated, although their pathogenic role in grain or cotton dust disorders is uncertain. In this review we critically address potential inflammatory mechanisms of airway alterations resulting from cotton or grain dust exposure. General mechanisms of bronchoconstriction are first presented, then specific studies dealing with either of the two dusts are discussed. We believe this area of research may be fruitful in dissecting mechanisms of bronchoconstriction and airway inflammation, especially as more human studies are undertaken.

Animals↗

PubMed1986

Acute symptoms following exposure to grain dust in farming.

History of acute symptoms (cough, wheezing, shortness of breath, fever, stuffy nose, and skin itching/rash) following exposure to grain dust was obtained from 661 male and 535 female current and former farmers. These symptoms were relatively common: 60% of male and 25% of female farmers reported at least one such symptom on exposure to grain dust. Association of cough, wheezing, shortness of breath, and stuffy nose with skin reactivity and capacity to form IgE is consistent with an allergic nature of these symptoms. Barley and oats dust were perceived as dust most often producing symptoms. On the other hand, grain fever showed a different pattern, i.e., it was not associated with either skin reactivity or total IgE. Smoking might modify the susceptibility to react to grain dust with symptoms. Only those who reported wheezing on exposure to grain dust may have an increased risk to develop chronic airflow obstruction.

Adult↗

PubMed1994

Influence of mineral dusts on metabolism of arachidonic acid by alveolar macrophage.

The alveolar macrophage (AM) responds to stimuli such as coal mine dust by releasing inflammatory mediators such as cytokines, growth factors, reactive oxygen species, and eicosanoids. Eicosanoids are synthesized by AM through the action of cyclooxygenase and lipoxygenase enzymes and serve to modulate the proinflammatory function of this cell as part of the lungs' host defense mechanism. Reactive oxygen species can be generated by AM as a by-product in the biosynthetic pathway of the prostaglandins. AM produces primarily prostaglandin E2, thromboxane A2, and leukotriene B4 as part of the cellular response to an inflammatory stimulus. There is evidence to suggest that eicosanoid production by AM is functionally linked to both surface interaction with mine dust particles like silica and by the phagocytosis of the dust particle itself. In this report, we examined the effects of an antioxidant, vitamin E, on dust-induced synthesis of PGE2 and TXB2 in vitro and in vivo by AM obtained by bronchoalveolar lavage from rats. We also looked at the effects of the surface of silica particles on AM eicosanoid biosynthesis under conditions of calcination, a process that removes exposed hydroxyl groups from the surface of silica particles, thus reducing the likelihood of soluble hydroxyl radical formation. Treatment of AM with vitamin E in vivo and in vitro reduced the augmentation in eicosanoid production usually observed when AM are exposed to mine dusts. These results suggest that vitamin E may effectively reduce the inflammatory and fibrotic response produced by inhalation of mineral dust through an antioxidant mechanism.(ABSTRACT TRUNCATED AT 250 WORDS)

Arachidonic Acid↗

PubMed2005

Health effects of natural dust: role of trace elements and compounds.

This article reviews the health effects of trace elements carried in natural dusts of geologic or geochemical origin. The sources of these dusts are diverse, including volcanoes, dust storms, long-range transport of desert dust, and displacement through natural processes such as landslides and earthquakes. The primary focus is dust exposures affecting communities rather than occupational groups (which have been comprehensively explored in other publications). The principal elements and compounds reviewed are trace metals (including As, Hg, Cd, and Fe), radioactive elements, fluoride, silicates, natural asbestiform compounds, and alkali salts. The pathways by which such agents affect human populations are explored, including carriage through water, air, soil, and the food chain. The mechanisms of biotoxicity and the acute and chronic consequences on health associated with these elements are described. The discussion explores problems inferring risk and disease causation from natural dust exposures using standard epidemiological indicators, particularly for chronic outcomes, and will argue for the importance of the ecological perspective in assessing pathogenesis. The authors stress the global scale of the problem, which remains underevaluated and underreported in terms of health implications.

Animals↗

PubMedDate not supplied

Adsorption of lipoproteins onto mineral dust surfaces: a possible factor in the pathogenesis of particle-induced pulmonary fibrosis?

We compare the adsorption behavior of high density lipoproteins (HDL) and low density lipoproteins (LDL) on "fibrogenic" and "nonfibrogenic" mineral dusts. The adsorption tests with bovine lipoprotein concentrate and human serum produced the following results: 1) All seven examined fibrogenic dusts (SiO2 DQ12, SiO2 F600, silica, graphite, TiC, kaolin, talc) adsorbed significantly more high density lipoproteins (HDL), than the five examined nonfibrogenic (inert) dusts (TiO2, SnO2, Al2O3, Fe2O3, Fe3O4). This different behavior was particularly conspicuous in the presence of competing adsorbates (serum proteins). 2) In contrast, the adsorption of LDL did not correlate with the fibrogenicity of the mineral dusts. 3) The known silicosis-protective substance polyvinylpyridine-N-oxide inhibits the HDL adsorption of alpha-quartz. These results indicate that the adsorption of HDL could have a causal relationship with the triggering of a fibrotic reaction. The adsorption on the surface of fibrogenic dust particles provides an exceptional opportunity for the intake of HDL by macrophages. During the phagocytosis of the inhaled dust particles, the HDL adsorbed on the surface of the particles could be taken up by macrophages regardless of the receptor. There the HDL particles and/or compounds associated with them, such as lecithin-cholesterol-acyltransferase, could stimulate the macrophages to release fibrogenic mediators by some yet unknown mechanism.

Adsorption↗

PubMed1987

[Air-borne dust and its protein in laboratory animal facilities].

Atopic individuals who were exposed to dust in animal rooms for a long time were more likely than non-atopics to have animal-related symptoms. Standard skin prick tests were performed using crude antigens from dander and urine, and 75 to 100% of atopic persons had positive skin reactions. It seems that allergens in animal rooms result from air-borne dust and the dust originates in animal urine and dander. The protein content occurs as dust particles both below and above 10 micron in diameter. The dust particles above 10 micron cannot pass through face masks, so half of the dust protein is arrested under the mask, but smaller particles pass through. In order to minimize the symptoms, we need to improve the design of cages, animal rooms, experimental rooms, ventilation systems and other protective equipment.

Adult↗

PubMed1999

The effect of dust lead control on blood lead in toddlers: a randomized trial.

BACKGROUND: Contaminated household dust is believed to be a major source of exposure for most children with elevated blood lead levels. To determine if a vigorous dust clean-up effort would reduce this exposure we conducted a randomized controlled field trial. METHODS: We randomized 113 urban children between the ages of 6 and 36 months: 56 children to a lead dust intervention composed of maternal education and biweekly assistance with household cleaning and 57 children to a control group. Household cleaning was done by two trained lay workers who focused their efforts on wet mopping of floors, damp-sponging of walls and horizontal surfaces, and vacuuming with a high-efficiency particle accumulating vacuum. Household dust lead levels, child blood lead levels, and maternal knowledge of lead poisoning and sources of exposure were measured before and after the intervention. RESULTS: Ninety-nine children were successfully followed for 12 +/- 3 months: 46 children in the lead group and 53 children in the control group. Age and blood lead were similar in the two groups at baseline and averaged 20 months and 12.0 micrograms/dL, respectively. Blood lead fell 17% in the intervention group and did not change among controls. Household dust and dust lead measures also fell significantly in the intervention group. Children in homes cleaned 20 or more times throughout the year had an average blood lead reduction of 34%. CONCLUSIONS: Regular home cleaning, accompanied by maternal education, is a safe and partially effective intervention that should be recommended for the large majority of lead-exposed children for whom, unfortunately, removal to lead-safe housing is not an option.

Air Pollution, Indoor↗

PubMed1999

Primary prevention of childhood lead exposure: A randomized trial of dust control.

BACKGROUND: Dust control is recommended as one of the primary strategies to prevent or control children's exposure to residential lead hazards, but the effect of dust control on children's blood lead levels is poorly understood. OBJECTIVE: To determine the effectiveness of dust control in preventing children's exposure to lead, as measured by blood lead levels, during their peak age of susceptibility. DESIGN: A randomized, controlled trial. SETTING: Rochester, NY. PARTICIPANTS: A total of 275 urban children were randomized at 6 months of age, of whom 246 (90%) were available for the 24-month-old follow-up visit. INTERVENTIONS: Children and their families were randomly assigned to an intervention group (n = 140), which received cleaning equipment and up to eight visits by a dust control advisor, or a control group (n = 135). OUTCOME MEASURES: Geometric mean blood lead levels and prevalence of elevated blood lead levels (ie, >10 microg/dL, 15 microg/dL, and 20 microg/dL). RESULTS: At baseline, children's geometric mean blood lead levels were 2.9 microg/dL (95% confidence interval [CI] = 2.7, 3.1); there were no significant differences in characteristics or lead exposure by group assignment, with the exception of water lead levels. For children in the intervention group, the mean number of visits by a dust control advisor during the 18-month study period was 6.2; 51 (36%) had 4 to 7 visits, and 69 (49%) had 8 visits. At 24 months of age, the geometric mean blood lead was 7.3 microg/dL (95% CI = 6.6, 8.2) for the intervention group and 7.8 microg/dL (95% CI = 6.9, 8. 7) for the control group. The percentage of children with a 24-month blood lead >/=10 microg/dL, >/=15 microg/dL, and >/=20 microg/dL was 31% versus 36%, 12% versus 14%, and 5% versus 7% in the intervention and control groups, respectively. CONCLUSIONS: We conclude that dust control, as performed by families and in the absence of lead hazard controls to reduce ongoing contamination from lead-based paint, is not effective in the primary prevention of childhood lead exposure.

Dust↗

PubMed2005

Relative ammonia concentrations, dust concentrations, and presence of Salmoneua species and Escherichia coli inside and outside commercial layer facilities.

Three air contaminants that may have serious health consequences to humans and poultry are ammonia, dust, and aerosolized bacteria. This study measured ammonia concentrations, dust concentrations, and the presence or absence of aerosolized Salmonella spp. and Escherichia coli inside and outside five commercial layer facilities. The average outside ammonia concentration measurements decreased as the distance from the facility increased from 10 to 40 ft. The measurements at 10 ft from the facilities were consistently higher than the average concentrations inside the facilities. The ammonia measurement trends inside of the facilities were affected by the temperature-dependent ventilation systems. Average dust concentrations inside the five facilities were consistently below 2 mg/m3. Three facilities also experienced average outside dust concentrations at all measured distances below 2 mg/m3. Two facilities had relatively high average dust measurements at 10 ft from ventilation fans (32.12 mg/m3 and 75.18 mg/m3). Escherichia coli and Salmonella were isolated from the air inside all five facilities and outside the facilities up to 40 ft from the ventilation fans. In condusion, dust concentrations may pose the largest risk to human and animal health at 10 ft away from the poultry facilities; risks associated with ammonia inhalation are greatest inside facilities during the coolest months of the year; and aerosolized bacteria are found inside and outside poultry facilities, but further work is needed to quantify the bacteria to further assess the health risk related to this issue.

Air Pollutants↗

PubMed1996

Lead-contaminated house dust and urban children's blood lead levels.

OBJECTIVES: This study assessed the relationship between lead-contaminated house dust and urban children's blood lead levels. METHODS: A random-sample survey was used to identify and enroll 205 children, 12 to 31 months of age, who had resided in the same house since at least 6 months of age. Children's blood and household dust, water, soil, and paint were analyzed for lead, and interviews were conducted to ascertain risk factors for elevated blood lead (> or = 10 micrograms/dL). RESULTS: Children's mean blood lead level was 7.7 micrograms/dL. In addition to dust lead loading (micrograms of lead per square foot), independent predictors of children's blood lead were Black race, soil lead levels, ingestion of soil or dirt, lead content and condition of painted surfaces, and water lead levels. For dust lead standards of 5 micrograms/sq ft, 20 micrograms/sq ft, and 40 micrograms/sq ft on noncarpeted floors, the estimated percentages of children having blood lead levels at or above 10 micrograms/dL were 4%, 15%, and 20%, respectively, after adjusting for other significant covariates. CONCLUSIONS: Lead-contaminated house dust is a significant contributor to lead intake among urban children who have low-level elevations in blood lead. A substantial proportion of children may have blood lead levels of at least 10 micrograms/dL at dust lead levels considerably lower than current standards.

Black or African American↗

PubMed2002

Effectiveness of a worksite intervention to reduce an occupational exposure: the Minnesota wood dust study.

OBJECTIVES: This study assessed the effectiveness of an intervention to reduce wood dust, a carcinogen, by approximately 26% in small woodworking businesses. METHODS: We randomized 48 businesses to an intervention (written recommendations, technical assistance, and worker training) or comparison (written recommendations alone) condition. Changes from baseline in dust concentration, dust control methods, and worker behavior were compared between the groups 1 year later. RESULTS: At follow-up, workers in intervention relative to comparison businesses reported greater awareness, increases in stage of readiness, and behavioral changes consistent with dust control. The median dust concentration change in the intervention group from baseline to follow-up was 10.4% (95% confidence interval = -28.8%, 12.7%) lower than the change in comparison businesses. CONCLUSIONS: We attribute the smaller-than-expected reduction in wood dust to the challenge of conducting rigorous intervention effectiveness research in occupational settings.

Adult↗

PubMed2005

Quantitation of house dust mite allergens (Der f 1 and group 2) on the skin and hair of dogs.

OBJECTIVE: To determine the concentration of house dust mite (HDM) allergens, Der f 1 and group 2, on the skin and hair of dogs and whether associations exist between the presence of Der f 1 and group 2 allergens on the skin and hair of dogs and household and dog characteristics. ANIMALS: 63 pet dogs from 50 homes. PROCEDURE: Dogs were weighed and body surface area in square meters was determined. Skin and hair samples were obtained by vacuuming dogs. Collected dust was analyzed by use of standard ELISA techniques. RESULTS: HDM allergen was detected in 21 of 59 skin and hair samples. Presence of group 2 allergen on skin and hair of dogs was significantly associated with long hair, compared with short or medium length hair. Median house dust sample concentrations of Der f 1 and group 2 allergens were high in homes with dogs that had skin and hair samples that were positive for Der f 1 and group 2 allergens. Dogs with skin and hair samples that were positive for Der f 1 and group 2 allergens resided in homes with a high number of house dust samples that were positive for Der f 1, group 2, or both allergens and in homes with a mean house dust sample allergen concentration of > or =2 microg/g of dust. CONCLUSIONS AND CLINICAL RELEVANCE: Associations exist between environmental HDM allergen concentrations and HDM allergens on the skin and hair samples of dogs. Environmental allergen load is a major factor in accumulation of allergens on the skin and hair of dogs.

Animals↗

PubMed1997

Comparative study of challenge aerosols for performance test for dust respirators.

A comparative study of challenge aerosols was conducted to review a performance test for dust respirators. The national approval test for dust respirator certification in Japan requires that air containing quartz particles of smaller than 2 microns in diameter should be used as the test aerosol. Aerosols with broad size distributions may therefore be used as the test aerosols. In view of the international harmonization of respirator certification standards, it is necessary to use alternative test aerosols for the approval test for dust respirators. The present study was undertaken to measure the collection efficiency of filters by using three kinds of test aerosols, i.e., quartz dust, sodium chloride and dioctyl sebacate mist aerosols. We used the cartridges of dust respirators and filtering facepieces from eight Japanese and foreign manufacturers, all of which have been certified by the national approval test. Good correlation among the measured collection efficiencies was found for the three test aerosols, but penetrations with sodium chloride and dioctyl sebacate mist aerosols were more than 10 times those of quartz dust aerosol.

Aerosols↗

PubMed1995

Dust suppression in swine feed using soybean oil.

Dust generation from swine feed (corn-soybean meal diet) treated with soybean oil was investigated using a cement mixer in a plywood box. Airborne total dust concentrations in the box were measured gravimetrically using a vacuum pump and filters while 12-kg feed samples were constantly mixed. The treatment factors were soybean oil concentration (0, 1, and 3%), corn bulk density (normal, 730 kg/m3 and low, 600 kg/m3), time of oil addition (before vs after grinding the corn), and storage time (0, 7, and 14 d). The feed was a mixture of soybean meal, base mix, and adjusted amounts of ground corn and soybean oil. Adding soybean oil after grinding at 1 and 3% levels to feed made with normal-bulk density corn suppressed total dust generation (3.39 and .99 mg/m3, respectively) (P < .001) compared with the no oil treatment (29.1 mg/m3). The 3% soybean oil treatment suppressed dust generation (.99 mg/m3) more than the 1% soybean oil treatment (3.39 mg/m3) (P < .001). Adding soybean oil after grinding the corn suppressed dust generation more than adding the oil to the corn before grinding for every oil level (P < .001). More dust was generated by feed made from low-bulk density corn than by feed made with normal-bulk density corn at every oil level (P < .001). There was no evidence of any storage time or treatment x storage time interactions.

Animal Feed↗

PubMedDate not supplied

Histological changes in the nasal mucosa in rats after long-term exposure to formaldehyde and wood dust.

Wood dust is a well known nasal carcinogen in man, as formaldehyde is in rats. In certain occupational environments, combined exposure to wood dust and formaldehyde is common. Little is known about the effects of this combination. A pilot study was performed on four groups of Sprague-Dawley rats: one exposed to wood dust (25 mg/m3), another to formaldehyde (12.4 ppm) and a third to both wood dust and formaldehyde; the fourth group served a control group. After 104 weeks of exposure the nose and lungs were examined histologically. One well differentiated squamous cell carcinoma was found in the formaldehyde group. Squamous cell metaplasia was found significantly more often among the formaldehyde-exposed rats. Squamous cell metaplasia with dysplasia was most frequently observed, however, in the group exposed to both formaldehyde and wood dust. There were also significantly more rats with pulmonary emphysema in the groups exposed to wood dust than in the other groups.

Animals↗

PubMed2003

Effect of a follow-up professional home cleaning on serial dust and blood lead levels of urban children.

Children residing in Philadelphia, Pennsylvania, who were enrolled in a clinical trial of oral chelation therapy (n=73) were studied to determine the effects of a follow-up professional lead dust cleaning of their homes 18 mo after an initial cleaning and commencement of therapy. Home dust lead levels were determined from dust-wipe specimens collected from the kitchen and playroom floors, and from a playroom windowsill, prior to, immediately following, and 3 and 6 mo after the second cleaning. Children's blood lead levels were assessed at 3-mo intervals before and after the follow-up cleaning. Professional cleaning produced immediate decreases in dust lead levels; however, dust lead re-accumulated to precleaning levels within 3-6 mo. Frequent, repeated cleanings may be required if blood lead or dust lead levels are to be reduced and sustained at low levels in urban homes.

Air Pollution, Indoor↗

PubMed2002

Organic dust exposure in dairy farmers in an alpine region.

OBJECTIVES: Epidemological studies suggest that farmers are at an increased risk for chronic obstructive pulmonary disease because of exposure to organic dust. We assessed the proportion of farmers among patients with end stage lung disease and we measured the seasonal exposure of dairy farmers to organic dust in a rural alpine region in Switzerland. METHODS: Six dairy farms of different sizes and infrastructures were chosen for measurements of organic dust (PM10 = particles with a 50% cut-off aerodynamic diameter of 10 gm). Indoor measurements were performed during 3-5 days at each farm in late winter, summer and early winter of one year. RESULTS: 17 measurements of organic dust were carried out on 6 different farms. The concentrations of PM10 ranged from 109-2207 microg/m3 for daily barn activities in winter months and from 76-4862 microg/m3 for hay storage in summertime. Exposure depended on farm infrastructure and season. It was higher in smaller and older cattle buildings and during the late winter months. The farmers were exposed to the measured amount of organic dust (PM10) for 5 to 6 hours per day during the winter (approximately 900-1260 hours/year). CONCLUSIONS: The study confirms a moderate to high exposure to organic dust (PM10) in these farmers, which, together with epidemiological data, suggests that such exposure over many years could be a major risk factor for the development of chronic obstructive pulmonary disease in dairy farmers.

Agricultural Workers' Diseases↗

PubMed1989

Respiratory health of brickworkers in Cape Town, South Africa. Appropriate dust exposure indicators and permissible exposure limits.

The predictive value for respiratory abnormalities of dust indicators was assessed for 268 brickworkers. The subjective/objective correlations were poor (r = 0.09). The subjective indicators were found to be predictive of early/mild abnormalities, while the objective indicators were better for more severe abnormalities. The respirable/total dust correlations were high (r = 0.99). Length of service was a good proxy predictor for most respiratory abnormalities, while respirable dust was a good proxy for respirable free silica. Simple screening measures with potential application in less-developed settings, like subjective questionnaire responses and total dust measurement, are suggested. The American Conference of Governmental Industrial Hygienists' threshold limit values for free silica and "nuisance" particulates appear to be too high to prevent the occurrence of abnormalities. The World Health Organization's health-based limit for respirable free silica (1 mg/m3) and hygienic standards of well below 5 mg/m3 would have prevented much of the respiratory abnormality found. Hygienic standards for dust and the concept of "nuisance" dust need to be reevaluated by further research.

Air Pollutants, Occupational↗