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Passive sampler used for simultaneous measurement of breathing zone size distribution, inhalable dust concentration and other size fractions involving large particles.

The particle size-dependent sampling velocity of the passive dust sampler developed by Vinzents (1996) is investigated under field conditions. Microscopical determination of the projected area equivalent diameter is used to quantify particles deposited on the sampler foils. Parameters for a semi-empirical model for particle deposition velocities on upward and forward facing foils are fitted to the data and it is shown that deposition mechanisms other than gravitational settling on the upward facing foil can be neglected. For calculation of airborne mass concentration no information on particle density is needed and only the ratio between the dynamic and volume shape factors needs to be known. Given the sampling velocity, the airborne mass per diameter interval is calculated from samples obtained in the wood industry, from which inhalable dust concentrations are calculated. The results are in line with parallel samples obtained with an inhalable dust sampler. A 'total' dust sampling characteristic can be fitted which reproduces measured 'total' dust with a closed face monitor. The results of this study demonstrate the validity of the passive dust sampling principle in environments involving even large (>100 microm) particles and the potential to predict the concentration of several size fractions.

Air Pollutants, Occupational↗

Exposure to inhalable dust, wheat flour and alpha-amylase allergens in industrial and traditional bakeries.

This study was designed to characterize exposure to inhalable dust, wheat flour and alpha-amylase allergens in industrial and traditional bakeries. The study included 70 bakeries from the northern part of Belgium. Based on the degree of automation and a clear division of individual job tasks, four bakeries were identified as industrial and the remaining 66 were identified as traditional ones. Personal, as well as stationary, samples of inhalable dust were collected during full shift periods, usually 5-7 h. The portable pumps aspirated 2 l/min through Teflon personal dust samplers (Millipore, pore size 1.0 microm) mounted in PAS-6 sampling heads. In the collected samples the inhalable dust, wheat flour and alpha-amylase allergens were determined. Wheat flour allergens were measured using enzyme-linked immunosorbent assay inhibition and an antiwheat IgG4 serum pool. The alpha-amylase allergens were measured using a sandwich enzyme immunoassay with affinity-purified polyclonal rabbit IgG antibodies. In total, 440 samples (300 personal and 140 stationary) were processed. The highest inhalable dust exposure was observed in traditional bakeries among bread [geometric mean (GM) 2.10 mg/m3] and bread and pastry workers (GM 1.80 mg/m3). In industrial bakeries the highest dust exposure was measured in bread-producing workers (GM 1.06 mg/m3). Similar relations were observed for wheat flour and alpha-amylase allergens. Bread baking workers in traditional bakeries had the highest exposure to both allergens (wheat flour GM 22.33 microg/m(3), alpha-amylase GM 0.61 ng/m3). The exposure to wheat flour and alpha-amylase allergens in industrial bakeries was higher in bread baking workers (wheat flour GM 6.15 microg/m3, alpha-amylase GM 0.47 ng/m3) than in bread packing workers (wheat flour GM 2.79 microg/m3, alpha-amylase GM 0.15 ng/m3). The data presented suggest that, on average, exposure in the Belgium bakeries studied-industrial as well as traditional-is lower than or similar to bakeries in The Netherlands, Canada, Sweden, the United Kingdom and Finland. Furthermore, the exposure levels in traditional bakeries seem to be higher than in industrial bakeries.

Allergens↗

An environmental nuisance: odor concentrated and transported by dust.

Intensive swine production generates odorous emissions which flow from the buildings housing the animals. High ventilation rates bring in fresh air, remove heat and moisture and enhance pork productivity. Numerous compounds contribute to the uniquely offensive odors from swine facilities, including fatty acids, amines, aromatics and sulfur compounds. Dust particles, which originate predominantly from feces and feed, can adsorb and concentrate odorants in swine facilities. In addition, organic particles can decay and generate odorous compounds. Odorants can exist in much higher concentrations in the dust particles than in equivalent volumes of air. Thus, inhalation of odorous dust and deposition of the dust particles in the mucus overlying the olfactory mucosa are likely responsible for some odor-related complaints by swine farm neighbors. Accurate prediction of odor transport and dispersion downwind from swine farms may require models of dust dispersion and correlation between dust and odorant levels. Unfortunately, many approaches to estimating odor impact currently incorporate filtering of air to remove particulate matter before sensing by humans or electronic sensors. Accelerated progress in understanding this and other 'real world' odor control problems will require methodological innovations that allow quantification of odor in response to air streams containing vapor and particulate phases.

Air↗

Analytical method development for 18 pesticides in house dust and settled residues using SEC, SPE, TMS methylation, and GC-MS.

An analytical method is developed to analyze eighteen pesticides in carpet dust and also dust that has settled on surfaces in order to determine the potential exposure of children to pesticide residues. For nonacid pesticides, the extract after centrifugation and filtration is cleaned up using size-exclusion chromatography (SEC) and then analyzed by gas chromatography (GC) coupled with a mass spectrometer (MS). The best solvent for extraction is ethyl acetate-cyclohexane (3:1). The recoveries of spiked nonacid pesticides from 2 g of dust are between 72% and 110% with a variation between 4.2% and 25.6%, and the detection limit is 10 to 50 ng/g dust, depending on the pesticide. For acid pesticides, the dust is extracted with a saturated Ca(OH)2 solution, centrifuged, cleaned up by polyvinylbenzene/polystyrene-type solid-phase extraction cartridges, and methylated with trimethylsilyldiazomethane (TMS). Acid pesticides on filter paper samples are extracted with acidified acetone (3 mM H3PO4) and methylated with TMS. Methylation with TMS is fast and easy to perform. Methyl esters of the pesticides are completely separated and detected at low levels by GC-MS in the selective ion monitoring mode. The average recoveries of pesticides from 2 g of dust are between 81% and 104%. The average recoveries of pesticides spiked on filter paper are between 88% and 113%. A capillary column with a stationary phase of trifluoropropylmethyl polysiloxane gives the best separation and sensitivity for most pesticides on the GC-MS.

Carboxylic Acids↗

Reducing airborne pathogens, dust and Salmonella transmission in experimental hatching cabinets using an electrostatic space charge system.

Electrostatic charging of particles in enclosed spaces has been shown to be an effective means of reducing airborne dust. Dust generated during the hatching process has been strongly implicated in Salmonella transmission, which complicates the cleaning and disinfecting processes for hatchers. Following two preliminary trials in which dust reduction was measured, four trials were conducted to evaluate the effectiveness of an electrostatic space charge system (ESCS) on the levels of total aerobic bacteria (TPC), enterobacteriaceae (ENT), and Salmonella within an experimental hatching cabinet. The ESCS was placed in a hatching cabinet that was approximately 50% full of 18-d-old broiler hatching eggs. The ESCS operated continuously to generate a strong negative electrostatic charge throughout the cabinet through hatching, and dust was collected in grounded trays containing water and a degreaser. An adjacent hatching cabinet served as an untreated control. Air samples from hatchers were collected daily, and sample chicks from each hatcher were grown out to 7 d of age for cecal analysis in three of the trials. The ESCS significantly (P < 0.05) reduced TPC and ENT by 85 to 93%. Dust concentration was significantly reduced (P < 0.0001) during the preliminary trials with an average reduction of 93.6%. The number of Salmonella per gram of cecal contents in birds grown to 7 d of age was significantly (P < 0.001) reduced by an average log10 3.4 cfu/g. This ionization technology is relatively inexpensive and could be used to reduce airborne bacteria and dust within the hatching cabinet.

Air Microbiology↗

Influence of dust loading on the alpha-particle energy resolution of continuous air monitors for thin deposits of radioactive aerosols.

Alpha-particle continuous air monitors must sometimes be operated in dusty environments where significant dust loading of the filter can be anticipated. It is important to understand how this dust loading affects the response of the continuous air monitors. Not only must a filter be changed if there is a reduction in airflow, but a change may be necessary if the energy resolution deteriorates and the continuous air monitor loses sensitivity and specificity for the radioactive aerosols of interest. A series of experiments were conducted to investigate alpha-particle energy resolution of continuous air monitor filters, particularly under dust loading conditions. Aerosol particles of various sizes were tagged with radon decay products to serve as surrogates for radioactive aerosols of interest such as plutonium or uranium. While the size of radioactive aerosols, filter type, and dust type affected the energy resolution, the thickness of an underlying (nonradioactive) dust layer did not show significant effect for the materials studied and a loading range of 0.01-10 mg x cm(-2). Our results indicate that it is possible for continuous air monitors to detect the release of radioactive aerosols with little deterioration in energy resolution under conditions of significant dust loading provided that the deposited layer of radioactive aerosols remains thin (< or = 0.1 mg x cm(-2)).

Aerosols↗

Depleted uranium dust from fired munitions: physical, chemical and biological properties.

This paper reports physical, chemical and biological analyses of samples of dust resulting from munitions containing depleted uranium (DU) that had been live-fired and had impacted an armored target. Mass spectroscopic analysis indicated that the average atom% of U was 0.198 +/- 0.10, consistent with depleted uranium. Other major elements present were iron, aluminum, and silicon. About 47% of the total mass was particles with diameters <300 microm, of which about 14% was <10 microm. X-ray diffraction analysis indicated that the uranium was present in the sample as uranium oxides-mainly U3O7 (47%), U3O8 (44%) and UO2 (9%). Depleted uranium dust, instilled into the lungs or implanted into the muscle of rats, contained a rapidly soluble uranium component and a more slowly soluble uranium component. The fraction that underwent dissolution in 7 d declined exponentially with increasing initial burden. At the lower lung burdens tested (<15 microg DU dust/lung) about 14% of the uranium appeared in urine within 7 d. At the higher lung burdens tested (~80-200 microg DU dust/lung) about 5% of the DU appeared in urine within 7 d. In both cases about 50% of that total appeared in urine within the first day. DU implanted in muscle similarly showed that about half of the total excreted within 7 d appeared in the first day. At the lower muscle burdens tested (<15 microg DU dust/injection site) about 9% was solubilized within 7 d. At muscle burdens >35 microg DU dust/injection site about 2% appeared in urine within 7 d. Natural uranium (NU) ore dust was instilled into rat lungs for comparison. The fraction dissolving in lung showed a pattern of exponential decline with increasing initial burden similar to DU. However, the decline was less steep, with about 14% appearing in urine for lung burdens up to about 200 microg NU dust/lung and 5% at lung burdens >1,100 microg NU dust/lung. NU also showed both a fast and a more slowly dissolving component. At the higher lung burdens of both DU and NU that showed lowered urine excretion rates, histological evidence of kidney damage was seen. Kidney damage was not seen with the muscle burdens tested. DU dust produced kidney damage at lower lung burdens and lower urine uranium levels than NU dust, suggesting that other toxic metals in DU dust may contribute to the damage.

Air Pollutants, Radioactive↗

Reduction of lung dust burden in pneumoconiosis by whole-lung lavage.

Pneumoconioses are characterized as irreversible, progressive respiratory diseases. No effective therapy exists to prevent progression of these diseases. Whole-lung lavage (WLL) might limit the rate of disease progression through the removal of dust, inflammatory cells, and cytokines. We performed WLL on a 54-year-old underground miner employed as a motorman and roof bolter and a 55-year-old driller at a surface coal mine. Both demonstrated normal lung function and chest radiographs showing ILO profusion category 2 nodular interstitial changes. From Subject 1, we recovered 5.24 x 10(8) cells (90% macrophages) from the right lung and 3.45 x 10(8) cells (94% macrophages) from the left lung. WLL removed 1.82 g of mineral dust (non-coal) on the right and 1.64 g on the left. From Subject 2, we recovered 7.49 x 10(8) cells (46% macrophages) from the right and 9.78 x 10(8) cells (69% macrophages) from the left lung. WLL removed 0.40 g of mineral dust on the right and 0.53 g on the left. Proinflammatory cytokines, growth factors, and cellular enzymes were also recovered. In cases of pneumoconiosis, WLL is capable of removing relatively large quantities of dust, cells, and soluble materials from the lungs. Only long-term follow-ups of individuals with progressive dust-induced disease who receive WLL therapy in the context of a clinical trial will provide information regarding the importance of removing mineral dust and inflammatory cells from the lung.

Bronchoalveolar Lavage↗

Wood dust and nasal cancer risk. A review of the evidence from North America.

In this article, biomedical literature assessing risks of nasal cancer and nonmalignant nasal pathology among woodworkers in North America is reviewed in detail and contrasted with experience from Europe and elsewhere. Exceptionally high rates of nasal adenocarcinoma have occurred among European hardwood furniture workers, but the epidemiologic evidence documents a disparity in findings between North America and Europe. Cohort studies of American wood-dust-exposed groups do not reveal excesses of nasal cancer, and wood-dust associations from US and Canadian case-control studies of nasal cancer tend not to be strong and differ across studies. Quantitative wood-dust exposure data are generally unavailable, but general dose information in European studies suggests that the excess risk of nasal cancer is associated with high levels of exposure. There is also an inconsistent association between wood-dust exposure per se and mucostasis or nasal histologic changes, and the mucostasis/metaplasia/dysplasia route to nasal cancer is still an unverified hypothesis. Considering the totality of evidence on the risk of cancer in exposed workers, it appears that wood-dust-related nasal adenocarcinoma essentially can be eliminated in Europe and its occurrence prevented in the United States if wood-dust exposures do not exceed an 8-hour time-weighted average 5 mg/m3 standard.

Adenocarcinoma↗

Ossicular fixation caused by bone dust after saccus decompression surgery.

HYPOTHESIS: To highlight the clinical and histologic features of ossicular fixation produced by bone dust during mastoid surgery. BACKGROUND: Bone dust deposition in the middle ear may occur during temporal bone surgery, but the ossicular fixation that may result from it remains underreported. METHODS: A case is reported of delayed conductive hearing loss after saccus decompression surgery resulting from ossicular fixation by bone dust deposition. RESULTS: Six months after the initial surgery, the patient experienced a 45 dB conductive hearing loss. The findings on second-look tympanotomy were stapes fixation and round window niche occlusion by newly formed tissue. Histologic examination of the latter showed fibrosis and new bone formation in reaction to particles of bone dust. New bone formation is a frequent concomitant of fibrosis in the middle ear and is probably not a growth from the bone dust. CONCLUSION: The use of high-speed drilling of bone in temporal bone surgery carries the risk of bone dust particle deposition in the middle ear. Measures are discussed that can be used to prevent this complication.

Audiometry, Pure-Tone↗

Asthma due to Central American walnut (Juglans olanchana) dust.

The purpose of our study was to describe a case of asthma due to Central American walnut (Juglans olanchana) dust and to ascertain whether an IgE antibody mechanism was implicated. The subject was a 48-year-old man who developed asthma following exposure to Central American walnut dust. Although intradermal testing with an aqueous extract of walnut dust produced no response, inhalation challenge with the extract produced significant bronchoconstriction. Another asthmatic person exposed to the wood dust had a positive skin test, but did not respond to the bronchial challenge. A direct radioallergosorbent test (RAST) on both subjects showed no evidence of serum IgE antibodies to Central American walnut dust. Consequently, the mechanism responsible for the sensitivity to the walnut dust remains unknown.

Asthma↗

Importance of house dust mite and Alternaria allergens in childhood asthma: an epidemiological study in two climatic regions of Australia.

The relation of house dust mite allergen levels to asthma and allergy was examined in two population samples of children aged 8-11 years in northern New South Wales. We studied 805 children in Lismore (a hot, humid, coastal region) and 770 in Moree/Narrabri (a hot, dry inland region). Respiratory symptoms were measured by questionnaire, bronchial hyperresponsiveness (BHR) by histamine inhalation test, and allergy by skin-prick tests. Current asthma was defined as the presence of both wheeze in last 12 months and BHR. Der p I levels were measured in dust from the bed and floors in the homes of 57 randomly selected children in the coastal region and of 74 inland children. Der p I levels were significantly higher by the coast (83.0 vs 11.2 microg/g, P < 0.001). House dust mite sensitivity was of similar prevalence in both regions (28.6 vs 26.4%, n.s.) but Alternaria sensitivity was higher inland (4.0 vs 15.2% P<0.001). Bronchial responsiveness was more severe in coastal children sensitized to house dust mites and in inland children who were sensitized to Alternaria. The adjusted odds ratios for current asthma in children sensitized to house dust mites were 21.3 (95% CI 10.5, 43.2) by the coast and 2.7 (95% CI 1.3, 5.4) inland, and in children sensitized to Alternaria were 3.4 (95% CI 1.3, 9.1) in the coastal region and 5.6 (95% CI 3.1, 10.1 inland. These studies suggest that high house dust mite allergen levels in a humid, subtropical region act to significantly increase bronchial responsiveness in sensitized children, and that Alternaria allergens have a similar but less potent action in a dry, rural region.

Allergens↗

Wheat antigen exposure assessment for epidemiological studies in bakeries using personal dust sampling and inhibition ELISA.

BACKGROUND: Asthma in bakery workers caused by exposure to wheat flour proteins is an important occupational health problem. Until recently, gravimetric dust measurements were the only available technique for quantitative exposure assessment in bakeries. However, it is questionable whether dust levels are a good exposure parameter or only give a crude approximation of the actual flour allergen concentration. OBJECTIVE: In the present study we have investigated a method to measure wheat flour antigens with immunochemical methods. METHODS: Wheat flour antigens were measured in 449 personal dust samples taken in bakeries, using enzyme-linked immunosorbent assay (ELISA) inhibition and an anti-wheat IgG4 serum pool. Western-blotting was performed to compare the wheat flour proteins detected by IgE and IgG4. RESULTS: Electrophoresis and immunoblotting showed that many wheat flour proteins can bind IgG4 and IgE, but also a reasonable similarity in major allergens detected by our IgG4-serum pool and IgE-positive sera. Inhibition tests showed some cross-reactivity with some cereal species, but not with other ingredients used in bakeries. In bakeries, large differences in personal airborne flour levels were found between occupational titles. For several groups clear differences in wheat antigen exposure levels existed, where no differences in dust exposure levels could be found. The relationship between dust and wheat antigen exposure varied considerably, depending on the specific bakery occupation, the size of the bakery, and the type of product produced by the bakery. This study also shows that personal sampling of wheat antigens is possible on a large scale and can be used for epidemiological field studies. CONCLUSION: Measurement of airborne wheat antigens in bakeries is a more specific and sensitive measurement tool than measuring dust samples, and will probably be essential for epidemiologic field studies focusing on exposure-response relationships.

Air Pollutants, Occupational↗

Clinical significance of the house dust mite (Dermatophagoides pteronyssinus) in asthmatic children in Japan.

Clinical studies were conducted to evaluate the role of the house dust mite. Dermatophagoides pteronyssinus, as an allergen in children's asthma in Japan. Skin testing and Prausnitz-Küstner type skin testing showed good correlations between the allergenicity of house dust and the mite. A positive Prausnitz-Küstner type skin reaction to house dust was neutralized by a mite extract. Radioallergosorbent test showed good correlation between house dust and the mite (r=0.687). The mite exhibited in vitro inhibition of radioallergosorbent test to house dust. The inhalation provocation test resulted in an acute respiratory attack in one of the patients. These results suggest that the house dust mite is an important allergen in asthmatic children in Japan.

Adolescent↗

Mite fauna and fungal flora in house dust from homes of asthmatic children.

Mite fauna and fungal flora in the house dust from homes of asthmatic children with positive and negative skin test to house dust allergen and non-asthmatic controls were examined. There was no conspicuous difference in mite species distribution among the three groups. Pyroglyphid mites dominate the mite fauna in house dust more than half of which being Dermatophagoides: D. pteronyssinus and D. farinae. There was no statistically significant difference in numbers between the two species and either species could dominate depending on the conditions of the individual houses. The average number of acarina in 0.5 g of fine dust did not differ statistically among the three groups; however, mite number per square meter floor differed between patients with positive skin test and negative skin test. The results suggest that house-cleaning might influence the possible sensitization of children. The genetic distribution of mould fungi in house dust was largely similar to that of airborne fungi. The average number of fungal colonies detected in 0.5 g of dust did not differ statistically among the three groups. Wallemia with its minute spores may cause sensitization but has so far been insufficiently investigated.

Allergens↗

Effects of cemented tungsten carbide dust on rat lungs following intratracheal injection of saline suspension.

In order to examine the effect of cemented tungsten carbide dust on the animal lung, saline suspensions were intratracheally administered into the lungs of rats in a single dosage. About one-fifth of the animals died during the first three days. The acute response of the lungs was hemorrhagic edema with intense alveolar congestion. The animals killed at six months all presented pulmonary lesions of patchy fibrosis in the vicinity of the deposited dusts, occasionally associated with focal traction emphysema and bronchobronchiolar ectasia. At twelve months, two-third of the animals had neither fibrosis nor dust deposition, although the remaining animals showed pulmonary lesions similar to those seen in the six-months responders. Fibrosis of the lungs seemed to consist of collapsed alveoli with condensation of the preexistent reticulin fibers, but without noticeable collagenization. It is supposed that both the early toxic and the late fibrogenic effects of the carbide dust are attributable to the cytotoxic action of cobalt present in the dust particles. It is possible that recovery of the pulmonary lesions results from removal of the dusts from the lesions.

Animals↗

The bioaccessibility of lead (Pb) from vacuumed house dust on carpets in urban residences.

Risk assessments for toxicants in environmental media via oral exposure often rely on measurements of total concentration in a collected sample. However, the human digestive system cannot dissolute all of a toxicant present in the binding matrix, and cannot absorb it with nearly 100% efficiency. In vitro bioaccessibility has been developed as a method to estimate oral bioavailability of a toxicant using a physiologically-based extraction procedure. Bioaccessibility measurements are more physiologically relevant than strong acid leaching measurements of concentration. A method for measuring bioaccessible lead in house dust was derived from the bioaccessibility method currently used for heavy metals in contaminated soils. House dust was collected from carpets in typical urban residences. Bioaccessible lead was measured in house dust (<75 microm) from the homes of 15 participants. The bioaccessibility ranged from 52.4% to 77.2% in gastric fluid, and 4.9% to 32.1% in intestinal fluid. House dust samples from five homes were analyzed to assess the relationship among lead bioaccessibility of three particle size fractions (<75, 75-150, and 150-250 microm). Changes in lead bioaccessibility as a function of particle size fraction were not significant for gastric fluid (p= 0.7019); however they were significant for intestinal fluid (p= 0.0067). This decrease of bioaccessibility may result from the readsorption of dissolved lead onto the dust particles or precipitation of lead with phosphates in a high-pH environment. The bioaccessibility data obtained for two biofluids were applied to the IEUBK model, and results for intestinal bioaccessibility of lead provide support for the model default value of 30% lead bioavailability of dust as a reasonable population indicator for dose, but the higher values for gastric bioaccessibility of lead appeared to provide an upper bound that approached actual blood lead levels in the children living in the studied homes. This upper bound seemed to overcome some of the limitations of the model when it lacks child-specific activity data and characterization of all exposure routes.

Biological Availability↗

Do central vacuum cleaners produce less indoor airborne dust or airborne cat allergen, during and after vacuuming, compared with regular vacuum cleaners?

UNLABELLED: Vacuum cleaners with a central exhaust may lead to lower airborne dust and allergen concentrations compared with regular vacuum cleaners. In 12 houses, equipped with a central vacuum cleaning system, a standardized vacuum cleaning protocol was performed comparing airborne dust and allergen concentrations between the central system and a regular cleaner. Airborne dust concentrations during (104 vs. 95 microg/m(3)) and after vacuum cleaning (38 vs. 36 microg/m(3)) were not significantly different. In houses with a cat, Fel d 1 concentrations were also not significantly different either during (6.12 vs.5.91 ng/m(3)) and after (0.64 vs. 0.91 ng/m(3)) use of the vacuum cleaners. Airborne dust and Fel d 1 concentrations increased considerably during use of both vacuum cleaners. Compared with central vacuum cleaning systems, conventional modern vacuum cleaners do not cause higher airborne dust or cat allergen concentrations during and after use. PRACTICAL IMPLICATIONS: This study shows that the amount of dust or cat allergen in the air during and after vacuum cleaning is similar when comparing a central vacuum cleaner with a regular vacuum cleaner. Therefore, allergen avoidance advice given to reduce exposure of allergic asthmatic patients to allergens, does not necessarily have to include switching to a central vacuum cleaner.

Air Pollution, Indoor↗