Quartz Exposure Research Articles

Historical respirable quartz exposures of industrial sand workers: 1946-1996.

Besides a clear relationship to silicosis, crystalline silica-quartz-has been associated with lung cancer, nonmalignant renal disease, and auto-immune disease. To study diseases associated with crystalline silica further, NIOSH conducted a cohort mortality study of workers from 18 silica sand plants, which had quarry, crushing, and bagging operations to produce industrial sand. Twelve of these plants also had grinding mills to produce fine silica powder. The historical crystalline silica exposures of workers at these plants were estimated to facilitate exposure-response analyses in the epidemiologic study. NIOSH obtained personal respirable dust measurement records from Mine Safety and Health Administration (MSHA) compliance inspections at all 18 plants and from the archives of seven plants which had collected samples. These samples had been analyzed for quartz content by x-ray diffraction. Although no personal samples were available before 1974, impinger dust measurements were reported for 19 silica sand plants in 1946; these data were converted and used to estimate exposures prior to 1974. Statistical modeling of the samples was used to estimate quartz exposure concentrations for workers in plant-job-year categories from the 1930s when mortality follow-up of the cohort began until 1988 when follow-up stopped. Between 1974 and 1996, there were 4,269 respirable dust samples collected at these 18 plants. The geometric mean quartz concentration was 25.9 microg/m(3) (GSD = 10.9) with a range from less than 1 to 11,700 microg/m(3). Samples below 1 microg/m(3) were given a value of 0.5 microg/m(3). Over one-third of the samples -37%) exceeded the MSHA permissible exposure limit value for quartz (PEL = 10 mg/m(3)/(%quartz + 2)) and half (51%) of the samples exceeded the NIOSH recommended exposure limit (REL=50 microg/m(3)). The samples were collected from workers performing 143 jobs within the 18 plants, but too few samples were collected from many of the jobs to make accurate estimates. Therefore, samples were combined into 10 categories of jobs performing similar tasks or located within the same plant area. The quartz concentrations varied significantly by plant, job, and year. Quartz concentrations decreased over time, with measurements collected in the 1970s significantly greater than those collected later. The modeled exposure estimates improve upon duration of employment as an estimate of cumulative exposure and reduce exposure misclassification due to variation in quartz levels between plants, jobs, and over time. Am. J. Ind. Med. 38:389-398, 2000. Published 2000 Wiley-Liss, Inc.

DNA Damage and Inflammation in the Rat Quartz Model: Differences in Inflammatory Response and Formation of Oxidative DNA Adducts to High and Low Dose of DQ12 Quartz

Chronic exposure to poorly soluble particles such as quartz and diesel soot produces dose-dependent inflammatory responses in the rat lung. It has been shown that the inflammation in the rat lung causes persistent oxidative DNA damage and mutations in proliferation-competent cells, which are thought to be critical for tumorigenesis. In measuring various inflammatory parameters to a multidose quartz exposure in parallel with the amount of 8-oxoguanine (8-oxoGua) on the cellular level in rat lung, mechanistic data for understanding the underlying processes could be gained. Rat lungs (female Wistar, 180–220 g/bodyweight) were instilled with quartz DQ12 (doses 0.3, 1.5, and 7.5 mg/animal; controls: corundum at the same doses and physiological NaCl) and analyzed 90 days after intratracheal instillation. The bronchoalveolar lavage (BAL) fluid was determined for inflammation markers (differential cell count, protein, lung surfactant lipids, and tumor necrosis factor alpha); tissue sections of lungs were investigated for the amount of 8-oxoGua on the cellular level using an antibody against 8-oxoGua. The results reflect different responses for quartz versus all controls and show a clear dose-response relationship. Quartz elicited inflammatory reponses determined in the BAL fluid even at the low dose (0.3 mg/animal). In contrast, the level of 8-oxoGua in the lung of animals exposed to 0.3 mg quartz was not statistically increased above controls, whereas doses of 1.5 mg and 7.5 mg caused significant elevations. The data obtained indicate a no-effect level for the persistence of the mutagenic DNA adduct 8-oxoguanine in the epithelial lung cells at a low-dose quartz exposure that is still inflammatoric and fibrogenic.

Risks of respiratory disease in the heavy clay industry.

OBJECTIVES: Little information is available on the quantitative risks of respiratory disease from quartz in airborne dust in the heavy clay industry. Available evidence suggested that these risks might be...

Respirable Dust and Crystalline Silica (Quartz) Exposure Resulting from Potato Harvesting Operations

Occupational exposure to silica dust has historically been known to cause chronicrespiratory conditions. Workers and workplaces within agricultural industries remainremoved from the attention of occupational health and safety. The identification anddegree of exposure to respirable dust, crystalline silica, and endotoxins throughout thepotato harvesting process has been uncharacterized. A description of the potentialoccupational risks in this setting was therefore warranted. The purpose of this researchwas to identify the components of dust during the fall potato harvest in the San LuisValley of southern Colorado. The agricultural practices specific to potato harvest, thegeographic region, and the soil of San Luis Valley are believed to contribute tooccupational risk. Testing sites included seven farms in this region, chosen based ontheir location, variable soil types, and owner interest. The following parameters:respirable dust, respirable silica, bacterial endotoxins, and particle identification byscanning electron microscopy were measured. All exposures were based on 8-h time-weightedaverages. Exposure impact included: location of the farm, soil type (sand,rock, loam), job description, weather conditions; wind, rain, wet or dry soil duringharvest, humidity, and temperature. Results of air monitoring include 122 samplescollected, 93 revealed the presence of respirable dust, 18 detected respirable silica(quartz). The maximum respirable dust exposure was 5.05 mg/m 3 , respirable silica0.105 mg/m 3 , and percent silica of 12.85%. This information will allow employers torecognize where respirable dust and silica are generated and allow for planning andcontrol implementation to adequately protect workers.

Quartz Exposure in the Slate Industry in Northern Norway

In this study we have measured exposure levels to quartz in different parts of the slate industry in Alta, Northern Norway. Full shift personal samples were collected from the breathing zones of outdoor and indoor workers in the slate quarries and a slate factory. The quartz content of respirable dust was between 7 and 41%. The slate factory had the lower quartz levels although 41% of total and 73% of respirable samples were above the Norwegian TLV for quartz. The average concentration of total quartz in the slate factory was 0.27 mg⧹m3 and the average concentration of respirable quartz was 0.12 mg⧹m3. Outdoor in the quarries the average levels of quartz were 0.58 and 0.13 mg⧹m3 for total and respirable quartz, respectively. From the beginning of the last decade most of the quarry-workers have built quarry halls to protect themselves against a cold winter climate. Inside in these quarry halls the average levels were 1.74 mg⧹m3 total quartz and 0.46 mg⧹m3 respirable quartz. Assessment of historical exposure showed that 32 of totally 45 quarry workers with available exposure history had a lifetime inhaled quartz dose of more than 10 g. There is reason to fear that silicosis will be an increasing problem among quarry workers if efforts to reduce quartz exposure are not put into effect.

Quartz Exposure in the Slate Industry in Northern Norway

Quartz Exposure in the Slate Industry in Northern Norway

Association of years of occupational quartz exposure with spirometric airflow limitation in Norwegian men aged 30–46 years

BACKGROUNDThe association between occupational quartz exposure and ventilatory function was investigated in men in a general population after adjusting for other potential determinants of outcome.METHODSAll eligible men aged 30–46 years...

Quartz exposures and severe silicosis: a role for the hilar nodes.

BACKGROUND: Two stonemasons working together in an environment with high concentrations of quartz pursued very different clinical courses; one died of rapidly progressive silicosis and the other developed hilar adenopathy...

Differences between rat alveolar and interstitial macrophages 5 wk after quartz exposure.

Macrophages play an essential role in pulmonary host defense. We investigated differences between rat alveolar (AM) and interstitial (IM) macrophages after exposure in vivo to quartz, an inducer of intensive alveolitis. Rats were exposed to 0.5 ml of saline without (n = 8) or with (n = 8) 10 mg of quartz by intratracheal instillation. In a third group (n = 8), 10 mg of surfactant were added to the quartz mixture. Five weeks later, AM were recovered by bronchoalveolar lavage and IM by mechanical fragmentation of the lung, followed by enzymatic treatment. Contamination of AM to the IM fraction was calculated to be 12-15%. After quartz exposure, the expression of major histocompatibility complex class Ia was increased in both AM and IM fractions. The receptor corresponding to human complement receptor 3 increased in AM after quartz exposure, and AM from quartz-exposed animals had a lower metabolic activation. Our findings indicate that IM are immunocompetent cells and that differences between AM and IM fractions occur upon quartz-induced inflammation. This response is not affected by addition of surfactant.

Risks of silicosis in coalworkers exposed to unusual concentrations of respirable quartz.

OBJECTIVES: To describe the radiographic changes in coalworkers exposed to unusual concentrations of respirable quartz during the 1970s, and to relate these to exposure measurements. METHODS: Men who had worked...

Surfactant prevents quartz induced down-regulation of complement receptor 1 in human granulocytes.

Quartz is known to induce an inflammatory response in the alveolar space by recruitment of different effector cells. We investigated the interaction between granulocytes and quartz with respect to expression of complement receptor type 1 (CR1) and CR3, with and without the presence of surfactant. Granulocytes from hemolyzed blood were stimulated by N-formyl-methionyl-leucyl-phenylalanine (fMLP), which mobilize the intracellular pool of CR1 to the surface, and the mean fluorescence intensity (MFI) measured by cytofluorometry was 47.4 (46-63.6) (median; interquartile range). Quartz exposure reduced the CR1 expression to 23.2 (22.8-30.6) MFI units (P < 0.01), a porcine surfactant preparation added during quartz exposure abolished the down-regulation completely, 47.7 (43.2-62.3) MFI units (P < 0.001). Similar results were obtained after preincubation of the cells with surfactant followed by quartz exposure. No significant influence on CR1 expression was found by a synthetic lipid mixture, nor was the CR3 expression affected. In conclusion, this study demonstrates that the presence of surfactant inhibits quartz induced down-regulation of CR1 on activated granulocytes.

96/06563 Analysis of quartz exposure data obtained from underground and surface coal mining operations

96/06563 Analysis of quartz exposure data obtained from underground and surface coal mining operations

Analysis of Quartz Exposure Data Obtained from Underground and Surface Coal Mining Operations

Abstract The Mine Safety and Health Administration (MSHA) yearly performs quartz analysis on approximately 9000 respirable coal mine dust samples collected for various occupations in U.S. coal mines. All occupational quartz exposure data gathered by MSHA since 1985 have been compiled and analyzed to characterize current occupational exposures to quartz; to determine if the quartz percentages of samples collected for different occupations have changed during the period 1985 through 1992; and to study the intramine variability associated with quartz sample percentages of selected occupations. Analysis of the occupational data shows that regardless of the type of coal extraction process used, there are a substantial number of occupational samples that contain greater than 5 percent quartz and show quartz exposures that exceed 100 μg/m3. In underground mining operations, approximately 30 percent of the samples collected at the continuous-miner operator and continuous-miner helper occupations on continuous-min...

Quartz Exposure Trends in Metal and Nonmetal Mining

Abstract Since the early 1970s the Mine Safety and Health Administration has enforced health and safety standards in metal and nonmetal mines and mills. A major concern is exposure to respirable dusts containing quartz. More than 134,000 full-shift air samples have been collected since 1974 by inspectors to determine compliance. Of these samples, more than 82,000 contained at least 1 percent quartz. The objective of this article is to show the trends in this subset of the respirable dust data. However, exposure trends are affected by periodic procedural and policy changes and by the compliance sampling strategy; thus these data may not be representative of industry-wide exposures. Since 1988, 24 percent of nearly 23,000 respirable dust samples containing at least 1 percent quartz exceeded the permissible exposure limit. Statistical analysis by the U.S. Bureau of Mines has identified the commodities, locations, and occupations with the highest quartz exposures. Commodities with more than 50 percent of the ...

Further information on aluminium inhalation in silicosis.

In previous studies, a significant reduction in biological activity of quartz by the surface chemistry of aluminium was noted. Aluminium lactate inhalation one month after quartz exposure significantly suppressed silicosis. In a recent study, it was noted that aluminium inhalation failed to alter the silicosis process after disease was recognised by standard chest radiography in the first year after monthly treatment. That study was extended with the same groups of sheep, the aluminium treated group received weekly aerosol of 100 mg of aluminium lactate for an additional two years. All sheep were evaluated at three-month intervals by chest radiography, lung function, and lung lavage. The sheep with silicosis had significantly reduced lung functions, increased cellularity, phospholipids, and hyaluronan. These changes persisted for several years without significant differences between the silicotic sheep with or without the aluminium aerosol treatment. Aluminium aerosol treatment of silicosis after radiographic recognition of disease and the end of exposure did not alter the disease process.

Quartz Exposure Levels in the Underground and Surface Coal Mining Industry

Occupational quartz exposure data gathered from the Mine Safety and Health Administration's respirable dust enforcement program and a program to monitor quartz exposure in several mining occupations were compiled and analyzed to assess the status of quartz exposures in the coal mining industry. The analysis showed that, in underground mines, a substantial number of samples contained greater than 5% quartz. Occupations that showed a high frequency of excessive quartz exposure included the roof bolter, continuous miner operator, and continuous miner operator helper. In surface coal mines the highwall drill operator and helper, bulldozer operator, scraper operator, and truck driver were frequently exposed to high quartz concentrations.

The origins of health standards for quartz exposure.

The origins of health standards for quartz exposure. H E AyerCopyRight https://doi.org/10.2105/AJPH.85.10.1453-a Published Online: October 07, 2011

Quartz Exposure Levels in the Underground and Surface Coal Mining Industry

Quartz Exposure Levels in the Underground and Surface Coal Mining Industry

Freshly fractured quartz inhalation leads to enhanced lung injury and inflammation. Potential role of free radicals.

Silicosis is a devastating pulmonary disease that continues to occur in industrial workplaces. Its pathogenesis is under critical evaluation, and this report provides new concepts on the possible early events that occur in lungs resulting from the inhalation of freshly fractured versus aged quartz in the development of two diverse disease entities. In this study, we evaluated the biochemical and pathologic changes in the lavagate and lungs of rats exposed to freshly fractured quartz (generated by jet milling), aged quartz (milled then aged for 2 mo prior to use), or clean air 5 h a day for 10 d over a 2-wk period. The concentration of crystalline quartz in the chambers averaged 20 mg/m3. Particle concentrations and particle size were similar for the freshly milled and aged quartz exposures. However, free radical concentrations associated with the freshly milled quartz samples were significantly higher than those for aged quartz. After a 2-wk exposure, animals were killed and studied by bronchoalveolar lavage and pulmonary histopathology. Inhalation of aged quartz increased the number of bronchoalveolar lavage cells, demonstrated histopathologic evidence of increased pulmonary infiltrates, showed enhanced concentrations of biochemical markers of lung injury, increased lipid peroxidation, and the ability of pulmonary phagocytes to produce more oxygen radicals. In general, all these pulmonary responses were significantly more pronounced after inhalation of freshly fractured quartz compared with aged quartz. In contrast, antioxidant enzymes showed decreased concentrations in the freshly fractured quartz-exposed group compared with the aged quartz-exposed animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of aluminum treatments on pulmonary retention of quartz in sheep silicosis.

Previous experiments with the sheep model of silicosis have demonstrated a reduction of the pathological activity of quartz after treatments with aluminum lactate (Al-lac), such as Al-lac pretreatment of intratracheally injected quartz or Al-lac inhalation of quartz-exposed animals. Preliminary data also suggested a more effective alveolar clearance of quartz treated with Al-lac. The present study was undertaken to fully document the effect of Al-lac treatments on the pulmonary retention of quartz. Sheep (on average, 27 per group) received a single injection in the tracheal lobe of either 100 mg/100 mL of alpha-quartz, 100 mg/100 mL of alpha-quartz followed by Al-lac inhalations at 1-month intervals, or 100 mg/100 mL of alpha-quartz Al-lac pretreated in vitro. Samples of lung parenchyma were analyzed at 2, 6, and 10 months after the injection. The quartz concentration in each sample was measured using the X-ray diffraction method. The concentrations were expressed in micrograms of quartz per milligram of dry lung parenchyma. The geometric mean concentrations in each of the three groups at 2 months were statistically different (ANOVA of the log values; p = .016) as well as at 6 months (ANOVA of the log values; p = .001). Al-lac clearly reduced the pulmonary retention of quartz. Both modalities of Al delivery were equally effective in clearing quartz up to 2 months, which may explain the documented reduction in pathological activities after in both forms of therapy. However, quartz soaked in Al-Lac solution was more effective than inhalation of Al-lac after quartz exposure. The half-life of both native quartz and quartz Al-lactate inhaled was 5.05 and 4.99 months, respectively, while it was 3.1 months for Al-treated quartz. Al-lac inhalations after the second month of exposure do not significantly affect the rate of clearance of deposited quartz.