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PubMed1996

Western red cedar dust exposure and lung function: a dose-response relationship.

The relationship between levels of cumulative red cedar dust exposure and decline in lung function was explored in an 11-yr follow-up study of 243 sawmill workers who participated in at least two occasions. We also studied 140 office workers in a similar manner as control subjects. Workers with asthma were excluded from the analysis. During the period of the study, 916 personal and 216 area samples of dust were collected from the sawmill. Cumulative wood dust exposure was calculated for each sawmill worker according to the duration and exposure in each job, based on the geometric mean of all dust measurements for that job. Average daily dust exposure was calculated by dividing the total cumulative exposure by the number of days of work. Workers were divided into low-, medium-, and high-exposure groups with mean daily level of exposure of < 0.2, 0.2 to 0.4, and > 0.4 mg/m3, respectively. Sawmill workers had significantly greater declines in FEV1 and FVC compared with office workers adjusted for age, smoking, and initial lung function. A dose-response relationship was observed between the level of exposure and the annual decline in FVC. We conclude that exposure to Western red cedar dust is associated with a greater decline in lung function which may lead to development of chronic airflow limitation.

Adult↗

PubMed1998

Mineral dusts directly induce epithelial and interstitial fibrogenic mediators and matrix components in the airway wall.

Exposure to mineral dusts is associated with the development of chronic airflow obstruction, probably mediated in part by dust-induced fibrosis of the small airways. To investigate the mechanism of fibrosis, we exposed rat tracheal explants to amosite asbestos, iron oxide, or titanium dioxide. Explants were then maintained in air organ culture, and the expression of genes encoding for various mediators and matrix components assessed by reverse transcriptase-polymerase chain reaction (RT-PCR). At 7 d, all dusts produced significant increases in platelet-derived growth factor-A (PDGF-A) and transforming growth factor-beta1 (TGF-beta1) gene expression compared with control; asbestos and titanium dioxide produced increases in PDGF-B, and titanium dioxide increased TGF-alpha expression. Only asbestos caused increases in procollagen expression. No dust increased expression of tumor necrosis factor-alpha (TNF-alpha), fibronectin, or tropoelastin. Elevations in these factors coincided temporally with transport of particles into the epithelium and then to the subepithelial space. By in situ hybridization, TGF-beta gene expression was found in both the epithelium and subepithelial (interstitial) space, and PDGF-B and procollagen gene expression in the subepithelial space. Chemical analysis showed a small increase in hydroxyproline, a measure of collagen content, in asbestos-treated explants. We conclude that mineral dusts can induce airway wall fibrosis by directly upregulating proliferative and fibrogenic mediators as well as matrix components in the airway epithelium and interstitium, and that neither airspace nor circulating inflammatory cells are required for these effects. Different mineral dusts produce different patterns of reaction.

Airway Obstruction↗

PubMed1987

Inhalation of road dust by human subjects.

We measured pneumomagnetic field strength (PMFS) in 42 healthy control subjects living in districts of Northern Japan with low levels of road dust pollution and in 39 healthy subjects living in areas with high levels of road dust pollution. Suspended road dust produced by studded tires increases from 30 micrograms/m3 during the summer season to levels as high as 400 micrograms/m3 during the snow season in the downtown areas of Sendai, Japan. Road dust retained in the lungs, containing 3% iron, was magnetized from the surface of the chest wall, and PMFS was measured. Three to 5 sequential PMFS measurements were made in each subject in March and October of 1984 and 1985, and in March 1986. The PMFS in control subjects in March 1984 was 37 +/- 14 pico-Tesla (mean +/- SD) and did not significantly differ from the PMFS in October 1984 or that in March 1985. In March 1984, the PMFS of the subjects in highly polluted areas was 95 +/- 100 pico-Tesla (mean +/- SD) and was significantly higher than that of control subjects (p less than 0.01) and subsequently decreased in March 1985 and in March 1986, corresponding to a decrease in suspended road dust brought about by a campaign to eliminate the use of studded tires. Our findings suggest that some road dust caused by studded tires is retained in the lungs.

Adult↗

PubMed1988

Antigenic analysis of household dust samples.

Household dust samples from the homes of 106 allergy clinic patients in Baltimore were analyzed for specific allergen content. Dust mite antigen content was determined by enzyme-linked immunosorbent assays (ELISA) specific for the major allergens of Dermatophagoides pteronyssinus, D. farinae, and D. microceras. Cat and dog antigen content were determined by ELISA using antisera for Fel d 1 (formerly cat allergen 1) and dog allergens 3 and 13, respectively. Mold content was assessed by culture with microscopic identification. Dust mite antigen was detected in 99% of homes (D. farinae, 95%; D. pteronyssinus, 88%; D. microceras, 31%), with total antigen content ranging from 50 ng/g dust (the lower limit of detection) to 30,170 ng/g (median, 1,123 ng/g). Animal allergens were found in 100% of samples (cat: range, 2 to 130,000 ng Fel d 1/g; median, 90 ng/g; dog: range, 112.5 to 585,000 IU/g; median, 2,719.5 IU/g). Although there were highly significant differences in antigen content (p less than 0.001) between homes with and without a particular pet in residence, many homes without pets contained pet allergens at high concentrations. Molds were also detected in 100% of homes (range, 4 to 761 colonies/30 mg dust; median, 72 colonies/30 mg). No correlation was demonstrated between antigen content and skin test results, a history of asthma, symptoms on allergen exposure, or the age of the home (except for molds) for any of the allergens detected. We conclude that dust mite allergens, cat and dog allergens, and molds are virtually ubiquitous in Baltimore homes and that our ability to predict the presence and relative quantities of these allergens on clinical grounds is very limited.

Adolescent↗

PubMed1990

Toxicity of intratracheally instilled cotton dust, cellulose, and endotoxin.

Cotton dust includes respirable particles containing endotoxin and elastase, agents associated with emphysema. To examine whether a respirable fraction of cotton dust could produce emphysema in an animal model, we intratracheally instilled hamsters with respirable cotton dust particles (0.75 mg/100-g animal), mass median aerodynamic diameter less than or equal to 4.8 microns, twice weekly for 6 wk. We also examined whether instilled endotoxin (255 micrograms/100-g animal) could produce emphysema in hamsters and whether cellulose (0.75 mg/100-g animal) is an appropriate inert comparison dust. A saline-instilled group was the control. Hamsters were killed 8 wk after the last instillation. Static pressure-volume deflation curves of air-filled excised lungs were analyzed to measure lung distensibility. Lungs were fixed in inflation using glutaraldehyde and were examined morphometrically to obtain surface area and numbers of granulomata. Endotoxin-treated animals had increased distensibility, reduced surface-to-volume (S/V) ratio, and morphologically apparent mild centrilobular emphysema. Cellulose-treated animals had decreased distensibility, normal S/V ratio, and significant numbers of granulomata with patchy areas of thickened interalveolar septa. Cotton-dust-instilled animals had normal distensibility, reduced S/V ratio, significant numbers of granulomata, and mild centrilobular emphysema. These data suggest that cotton dust produces a significant parenchymal lesion with elements similar to both the emphysematous response to endotoxin and the fibrotic nodular response to cellulose.

Animals↗

PubMed1979

Human response to controlled levels of inert dust.

We studied nasal mucous flow, airway resistance, and subjective response in 16 young healthy subjects during 5-hour exposures to 2, 10, and 25 mg of inert dust per m3 in an environmental chamber. The dust was a fully polymerized plastic dust containing carbon black. The number of these particles in room air, expressed as a per cent of the total number of particles was 36, 41, 14, 7, and 2, respectively, for the aerodynamic size ranges less than or equal to 1.8, 1.9 to 5.3, 5.4 to 8.9, 9.0 to 12.4, and greater than or equal to 12.5 micron. No significant changes in nasal mucociliary clearance rate or nasal resistance were observed. At all dust concentrations there was a decrease in 1-sec forced expiratory volume, but not in the forced vital capacity or the forced expiratory flow during the middle half of the forced vital capacity. The nasal penetration fraction of particles was approximately 55 per cent for the smallest particles and 20 per cent for the largest particles. Discomfort was proportional to the concentration of dust, but lagged almost 2 hours behind the changes in dust concentration. The discomfort was never excessive; the main complaints were dryness in the nose and pharynx.

Adult↗

PubMed1985

Pulmonary function and peripheral airway disease in patients with mineral dust or fume exposure.

Cigarette smoking and mineral dust exposure combined result in small airways function abnormalities difficult to distinguish from smoking effects alone. To determine if mineral dust or fume exposure in smokers results in additional changes in small airways structure and function, we studied small airways disease and pulmonary function in 25 persons (62.4 +/- 8.8 yr) with exposure to mineral dust or fume for 10 yr or more and compared them individually with control subjects without dust exposure (61.8 +/- 8.5 yr) matched for age, smoking history, and lobe resected. All subjects were patients undergoing surgical resection for isolated coin lesions. Occupational histories and measurements of lung volumes, flow rates, small airways function, diffusing capacity, and pressure-volume relationships were obtained preoperatively. Membranous bronchioles were graded for the presence and degree of mural inflammation, fibrosis, muscle, pigment, and squamous and goblet cell metaplasia. Respiratory bronchioles were similarly graded for inflammation, fibrosis, muscle, pigment, and lumenal macrophages. The dust-exposed group had increased fibrous tissue deposition and goblet cell metaplasia in the membranous bronchioles (p less than 0.05). When the exposed group was divided according to occupation into miners (n = 13) and nonminers exposed in other dusty jobs (n = 12), the pathologic changes were evident in both exposed groups. No differences in pulmonary function were seen between the 2 groups. We conclude that occupational exposure to mineral dust and fume produces structural changes in peripheral airways that are greater than those seen with smoking alone, but these changes were not associated with a greater deterioration in lung function.

Aged↗

PubMed1993

LFA-1 and ICAM-1 in homotypic aggregation of rat alveolar macrophages: organic dust-mediated aggregation by a non-protein kinase C-dependent pathway.

We have examined the role of cell adhesion molecules in the homotypic aggregation of rat alveolar macrophages after exposure to wool and grain dusts. Molecules such as bacterial lipopolysaccharide (LPS) and phorbol myristate acetate (PMA) can upregulate adhesion molecules, resulting in aggregation of lymphocytes. In rats treated intratracheally with an inspirable sample of wool dust collected from the air of British wool textile mills, and sieved grain dust, aggregates of macrophages were present in the bronchoalveolar lavage (BAL). Our hypothesis was that substances present on the dust surface could activate and upregulate adhesion molecules of the CD11/CD18 complex on the BAL cells and account for the aggregates. Macrophages from untreated rats form aggregates in vitro, which averaged 19 cells/aggregate; when treated with both wool and grain dusts, this rose to 25 and 24 cells/aggregate, respectively. LPS, PMA, and the proinflammatory cytokine tumor necrosis factor (TNF) also caused increases in aggregate size. Staurosporine, an inhibitor of protein kinase C (PKC), reduced the number of cells per aggregate from 35 cells/aggregate in LPS- and PMA-treated macrophages to 18 cells/aggregate, the same as untreated. In contrast, staurosporine had no effect in reducing the size of aggregates produced by the organic dusts. Removal of divalent cations, which are essential for maintaining integrin stability and PKC activity, resulted in complete abolition of aggregate formation. Treatment with monoclonal antibodies to lymphocyte function-associated antigen-1 (LFA-1) alpha and beta and intercellular adhesion molecule-1 (ICAM-1) resulted in the inhibition of aggregate formation in a dose-dependent manner.(ABSTRACT TRUNCATED AT 250 WORDS)

Alkaloids↗

PubMed1970

Respiratory mechanics and dust exposure in byssinosis.

Acute exposures to hemp dust, in healthy subjects as well as hemp workers with byssinosis, resulted in two different responses. Men with symptoms (chest tightness, coughing, and wheezing) after exposure showed decreases of forced expiratory volumes (FEV(1.0)), flow rates on maximum expiratory flow-volume (MEFV) curves, and of vital capacity (VC), while airway conductance (Gaw: TGV ratio) did not decrease significantly ("flow rate response"). Men without symptoms after exposure showed no changes of VC, FEV(1.0), and MEFV curves, but had a significantly decreased airway conductance ("conductance response"). The flow rate response is attributed to a pharmacological bronchoconstrictor effect of hemp dust on small airways, the conductance response to a mechanical or reflex effect of hemp dust on large airways. Both responses were abolished by a bronchodilator drug. The type of response reflects a difference between individuals and is not related to age, smoking habits, or prior exposure history. Men with normal control function data had either a flow rate or a conductance response. All men with abnormal control data had a flow rate response.Long-term hemp dust exposure causes irreversible obstructive lung disease, in particular among men who respond to acute dust exposure with symptoms and flow rate decreases. The detection of this response, with FEV(1.0) measurements and MEFV curves, is essential in the study of byssinosis. Decreases of airway conductance after dust exposure have no consistent relation to the development of clinical symptoms. The relative value of measurements of maximum expiratory flow rates and of airway conductance in other lung diseases needs to be reassessed.

Bronchodilator Agents↗

PubMed1990

Consequences of middle ear bone dust during neurotologic surgery.

Most otologists are cautioned at some point in their training that if bone dust is allowed to enter the middle ear while the mastoid is being drilled, there may be adverse consequences. Two cases of ossicular fixation and conductive hearing loss after retrolabyrinthine vestibular nerve section prompted us to examine the issue of bone dust in the middle ear. In a study of 13 temporal bones that had undergone neurotologic surgery, we found 11 that showed evidence of viable bone dust in the middle ear, and three that had ossicular fixation. Viable bone dust was always encased in a mucous membrane lining. These findings suggest that bone dust that enters the middle ear may indeed remain viable and cause ossicular fixation. The surgeon should therefore take every precaution to prevent bone dust from entering the middle ear during neurotologic procedures in which conservation of hearing is attempted.

Bone and Bones↗

PubMed2026

Unveiling microbial risks in Chinese household dust: a comprehensive analysis from absolute abundance to virulence unit.

BACKGROUND: People spend the majority of their lives indoors, yet the risk and virulence potential of household microbiota remain largely unexplored, particularly in developing countries. RESULTS: Here, we conducted a nationwide survey on both dust samples and health information across 118 Chinese households. The microbiota composition and its functional units were analyzed using absolute 16S rRNA/ITS sequencing, metagenomics, and metaproteomics. Cross-domain network analysis of the core microbial communities revealed robust co-occurrence patterns in household dust. The mean absolute abundance of potentially pathogenic bacteria and fungi in households was 2.39 × 105 and 2.83 × 106 DNA copies/g dust. The potentially pathogenic community was primarily influenced by latitude, relative humidity, and average temperature. Although total absolute abundance was substantially lower in urban areas, the relative abundance of potentially pathogenic bacteria was markedly higher compared to rural environments. While urban-rural differences existed, the underlying statistical drivers were the environmental variables. The absolute abundance of potential pathogens was significantly associated with the prevalence of rhinitis, wheeze, and dermatitis in 266 participants. Children were identified as the highest-risk group from inhalation exposure of average daily dose. A total of 170 bacterial, 223 fungal virulence factors (VFs), and 370 antibiotic resistance genes (ARGs) were detected in dust and dust extracellular vesicle (EV)-associated DNA. EV-associated cargoes contributed 47.13% to the bacterial VF profiles, 11.90% to fungal VF profiles, and 44.45% to ARG profiles. Metaproteomic analysis confirmed the presence of VF profiles in dust EVs, which was further verified by curated proteomics data from 35 household pathogens. CONCLUSIONS: This study provides a comprehensive, quantitative framework linking indoor microbial exposure to health risks, highlighting EVs as a non-negligible, novel, extracellular mechanistic pathway for health impact in household environments. Video Abstract.

Child↗

PubMed2001

Dermal exposure assessment of polycyclic aromatic hydrocarbons: in vitro percutaneous penetration from coal dust.

To understand the dermal uptake of chemicals bound to soil and dust, information on the neat substance is helpful but does not seem sufficient. Because of its content of polycyclic aromatic hydrocarbons (PAHs) coal is suspected to be carcinogenic. However, experimental carcinogenity studies on coal dust never succeeded in demonstrating a higher incidence of cancer in treated animals. The aim of the study was to assess dermal penetration through human skin of PAHs from coal dust. A sample of coal dust was grinded and sieved, using the particle size of < 30 microm. An in vitro static diffusion cell system validated by in vitrolin vivo comparison has been used to study dermal penetration through human skin of PAHs from coal dust compared with their percutaneous absorption as pure compounds. No percutaneous penetration of PAHs was observed in the cells where coal dust was applied, while dermal penetration was demonstrated for PAHs applied in an acetone solution. Results agree with the literature that PAHs are poorly absorbed through the skin from solids. Dermal risk assessment of PAHs should take into account not only the degree and the extent of skin contamination, but also their bioavailability, which is heavily influenced by the physico-chemical characteristics of the matrix.

Administration, Cutaneous↗

PubMed2000

Longitudinal study of dust and airborne endotoxin in the home.

To characterize the seasonal variability of endotoxin levels, we measured endotoxin in dust from the bed, bedroom floor, and kitchen floor in 20 homes, and in air from the bedroom in 15 of the homes. All homes were located in the greater Boston, Massachusetts, area and were sampled each month from April 1995 to June 1996. Outdoor air was collected at two locations. We found greater within-home than between-home variance for bedroom floor, kitchen floor, and airborne endotoxin. However, the reverse was true for bed dust endotoxin. Thus, studies using single measurements of dust endotoxin are most likely to reliably distinguish between homes if bed dust is sampled. Dust endotoxin levels were not significantly associated with airborne endotoxin. Airborne endotoxin was significantly (p = 0. 04) and positively associated with absolute humidity in a mixed-effect model adjusting for a random home effect and fixed effect of sampling month and home characteristics. This finding implies that indoor humidity may be an important factor controlling endotoxin exposure. We found a significant (p < 0.05) seasonal effect in kitchen floor dust (spring > fall) and bedroom airborne endotoxin (spring > winter), but not in the other indoor samples. We found significant seasonal pattern in outdoor airborne endotoxin (summer > winter).

Air Pollution, Indoor↗

PubMed2002

Dust: a metric for use in residential and building exposure assessment and source characterization.

In this review, we examine house dust and residential soil and their use for identifying sources and the quantifying levels of toxicants for the estimation of exposure. We answer critical questions that focus on the selection of samples or sampling strategies for collection and discuss areas of uncertainty and gaps in knowledge. We discuss the evolution of dust sampling with a special emphasis on work conducted after the publication of the 1992 review by McArthur [Appl Occup Environ Hyg 7(9):599-606 (1992)]. The approaches to sampling dust examined include surface wipe sampling, vacuum sampling, and other sampling approaches, including attic sampling. The metrics of presentation of results for toxicants in dust surface loading (micrograms per square centimeter) or surface concentration (micrograms per gram) are discussed. We evaluate these metrics in terms of how the information can be used in source characterization and in exposure characterization. We discuss the types of companion information on source use and household or personal activity patterns required to assess the significance of the dust exposure. The status and needs for wipe samplers, surface samplers, and vacuum samplers are summarized with some discussion on the strengths and weaknesses of each type of sampler. We also discuss needs for research and development and the current status of standardization. Case studies are provided to illustrate the use of house dust and residential soil in source characterization, forensic analyses, or human exposure assessment.

Air Pollution, Indoor↗

PubMed1983

Effect of mineral dusts on metabolic cooperation between Chinese hamster V79 cells in vitro.

The mode of action of inorganic fibers as carcinogens is unknown. There is conflicting evidence whether they act by inducing lesions in DNA, such as initiating carcinogens, or alternatively act as promoters of carcinogenesis. Recent evidence has suggested that promoters inhibit the process of cell-to-cell chemical communication known as metabolic cooperation. Chinese hamster V79-4 cells in culture exhibit metabolic cooperation which can be blocked by the promoter tetraphorbol-13-acetate (TPA). Three kinds of mineral dust were tested to determine whether or not they could interfere with the intercellular communication. The three dusts studied were: amosite, a fibrous asbestos from the Union Internationale Contre le Cancer (UICC) standard reference series, which is a typical carcinogenic fibrous dust inducing pleural tumors following intrapleural injection into rats; ball-milled amosite, a nonfibrous dust derived from UICC amosite by ball-milling, which has the physical properties characteristic of a noncarcinogenic dust; and Min-U-Sil silica, a widely available sample of fibrogenic quartz which does not induce pleural tumors following intrapleural injection into rats. The results demonstrated that metabolic cooperation between V79-4 cells cannot be reduced by carcinogenic asbestos fibers or by relatively large numbers of nontoxic dust particles. It is concluded that if inorganic fibers promote carcinogenesis, then they do not operate by blocking metabolic cooperation.

Animals↗

PubMed1986

Cotton dust concentrations and particle size distributions associated with genotypes.

The problem of byssinosis has plagued cotton textile mills for hundreds of years, and it is still a problem today. With the regulations on airborne raw cotton dust set by OSHA and the ACGIH, research regarding the measurement of cotton dust in lint fiber is a necessity. A procedure known as the mass concentration particle size distribution (MCPSD) technique, developed at Texas A&M University, was used to measure the characteristics of cotton dust as affected by harvesting method and genotype. Cotton genotypes from three harvest seasons were analyzed by using a Coulter Counter, Model TAII, to obtain the mass concentrations and particle size distributions of dust present in the lint fiber. The genotypes were subjected to both hand harvesting and conventional spindle harvesting for comparison purposes. Results from the dust concentration analyses of particles less than 100 micron, 16 micron, and 8 micron in diameter, respectively, are presented. Also, a proposed procedure to obtain large quantities of "cotton dust" from gin trash material is discussed.

Byssinosis↗

PubMed1986

Evaluation of mechanical prototype machines for continuous separation of respirable cotton dust fractions.

The original cotton particulates analyzer used stationary screens to separate aerodynamically the coarse and fine dust fractions from small samples of cotton. By replacing stationary with rotary screens that were continuously cleaned, larger supplies of respirable dust were obtained without interruption. A ginned and a waste cotton were used to test two methods of separation: a rotating 38-micron screen and a tandem rotating 710- or 38- micron screen and cyclone. The fine dust fractions from both systems were captured on filters and examined gravimetrically, by Coulter counter, and scanning electron microscope. The dust passing 38 micron stationary or rotary screens contained particles of 15 micron maximum diameter whereas dust from the 710-gmm rotary screen and tandem cyclone exhibited particles of 10 micron maximum diameter and lint fragments. Dust fractions with particles less than 10 micron diameter and free of lint were obtained with a 38-micron rotary screen and tandem cyclone.

Air Pollutants, Occupational↗

PubMed1986

Physical properties of five grain dust types.

Physical properties of grain dust derived from five grain types (soybean, rice, corn, wheat, and sorghum) were measured and reported. The grain dusts were obtained from dust collection systems of terminal grain handling facilities and were assumed to be representative of grain dust generated during the handling process. The physical properties reported were as follows: particle size distributions and surface area measurements using a Coulter Counter Model TAII; percent dust fractions less than 100 micron of whole dust; bulk density; particle density; and ash content.

Dust↗