Journal of Exposure Analysis and Environmental Epidemiology最新文献

{"title":"Industrial hygiene sampling and applications to ambient silica monitoring.","authors":"F J Hearl","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Interest in ambient exposures to silica has prompted an evaluation of the applicability of the industrial hygiene sampling and analysis experience. Exposure to excessive levels of silica in the workplace has long been recognized as a risk factor for the development of a variety of disabling and sometimes fatal lung diseases. Initial efforts to control occupational exposure to dust were based on reducing exposures as measured by particle-counting techniques. Because silicosis, the disease resulting from exposure to silica, occurs in the lower airways, which can be reached only by small \"respirable dust\" particles, size selective sampling procedures were introduced for dust monitoring. The analysis of silica in collected dust samples also has undergone development. Initial methods used involved acid digestion of soluble silicates, with subsequent chemical analysis of the insoluble \"free silica\" fraction. Current methodology relies on the use of X-ray diffraction and infrared technologies to quantify these materials. However, these methods are sensitive to the particle size distribution of the samples. Standard reference materials (SRMs) have been developed for use with respirable size dust samples. Ambient particulate matter is now measured using the U.S. Environmental Protection Agency sampling methods for particulate matter < or = 10 microns, which approximate the collection efficiency for thoracic fraction samplers. Because the existing calibration SRMs were produced for the measurement of occupational crystalline silica, the need to develop appropriate standards and methods for ambient silica measurements should be evaluated.</p>","PeriodicalId":15789,"journal":{"name":"Journal of Exposure Analysis and Environmental Epidemiology","volume":"7 3","pages":"279-89"},"PeriodicalIF":0.0,"publicationDate":"1997-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20190895","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Soil derived dust as a source of silica: aerosol properties, emissions, deposition, and transport.","authors":"D Gillette","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Quartz is an abundant mineral in wind generated dust throughout the United States. Of the 18.9 million tons of particles smaller than 10 microns (PM10) dust emitted into the atmosphere by the wind, a significant fraction is silica. Transport of some of this silica to populated areas is possible.</p>","PeriodicalId":15789,"journal":{"name":"Journal of Exposure Analysis and Environmental Epidemiology","volume":"7 3","pages":"303-11"},"PeriodicalIF":0.0,"publicationDate":"1997-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20188891","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Initiating the risk assessment process for inhaled particulate materials: development of short term inhalation bioassays.","authors":"D B Warheit,&nbsp;M A Hartsky","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>This study describes a short term inhalation bioassay in rats to predict the potential for inhaled particles to produce chronic lung disease in humans (e.g., pulmonary fibrosis). To validate the method, rats were exposed for 6 h or 3 days to various concentrations of two reference materials: (1) a known fibrogenic material (i.e., aerosolized alpha-quartz silica particles in the form of Berkeley Min-U-Sil (Pennsylvania Glass and Sand Company, Pittsburgh, PA), or (2) carbonyl iron (CI) particles, as a negative control. Cells and fluids from groups of sham and dust exposed animals were recovered by bronchoalveolar lavage (BAL). Alkaline phosphatase, lactate dehydrogenase and protein values were measured in BAL fluids at several times postexposure. Cells were identified, counted, and evaluated for viability. The lungs of additional exposed animals were processed for histopathology. Although particle deposition patterns for the two dusts were similar, brief exposures to silica particles produced a persistent pulmonary inflammatory response characterized by neutrophil recruitment at sites of particle deposition and consistently elevated biomarkers of cytotoxicity in BAL fluids. In addition, alveolar macrophage clearance functions were impaired. Progressive histopathologic lesions were observed within 1 mo after a 3-day exposure. Light and electron microscopy of silica exposed lung tissue revealed a chronically active pulmonary inflammatory response characterized by hyperplasia of Type II alveolar epithelial cells and the infiltration of macrophages and neutrophils into alveoli and interstitial compartments. The lesions were progressive, leading to the development of a multifocal, granulomatous-type pneumonitis within 2 mo postexposure. In contrast to the observed effects of silica, 3-day exposures to CI particles produced no significant adverse biochemical or histopathological effects on pulmonary tissues. These results demonstrate that short term, high dose inhalation exposures of silica produce effects similar to those previously observed using intratracheal instillation or chronic inhalation models and lend support to this method as a reliable short term bioassay for evaluating the pulmonary toxicity and mechanisms associated with exposure to new and untested respirable materials.</p>","PeriodicalId":15789,"journal":{"name":"Journal of Exposure Analysis and Environmental Epidemiology","volume":"7 3","pages":"313-25"},"PeriodicalIF":0.0,"publicationDate":"1997-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20188892","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Noncancer inhalation toxicology of crystalline silica: exposure-response assessment.","authors":"J S Gift,&nbsp;R A Faust","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Silicosis from inhalation of silica has long been recognized as an occupational hazard. Concern has arisen regarding the potential risk of silicosis from ambient silica (primarily quartz dust). This presentation reviews available data regarding ambient silica levels and estimates of the risk of silicosis at low exposure levels as they relate to the current U.S. Environmental Protection Agency National Ambient Air Quality Standards (NAAQS) for particulate matter. Current data indicate that for individuals not compromised by other respiratory ailments and for ambient environments expected to sustain 10% or less silica fraction in particulate matter with a mean aerodynamic diameter of < or = 10 microns (PM10), maintenance of the 50 micrograms/m3 annual NAAQS for PM10 is adequate to protect against fibrotic effects from ambient silica exposures. Issues such as the large divergence of risk estimates within the occupational setting (particularly at high cumulative exposures) and factors to consider for extrapolating risk in an occupational setting to risk from ambient exposure are discussed.</p>","PeriodicalId":15789,"journal":{"name":"Journal of Exposure Analysis and Environmental Epidemiology","volume":"7 3","pages":"345-58"},"PeriodicalIF":0.0,"publicationDate":"1997-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20188893","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Laboratory studies on silica induced toxicity and relationship to carcinogenicity.","authors":"J Rabovsky","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>A review of published laboratory studies was undertaken to provide insight into the biologic basis for silica induced lung toxicity. Experimental animals exhibit markers of silica induced toxicity similar to those exhibited by humans and may also provide a model for resistant populations. Cell culture studies are useful to discern the roles of specific lung cell types and cell mediators in the development of silica induced fibrotic events. The biochemical relationships between silica induced fibrosis and carcinogenesis have not been fully established. Temporal and dose-response relationships for events linking the two endpoints are unknown. Research in this area will provide a more complete understanding of the relationship between the two disease states and hence of the role of silica exposure in human disease.</p>","PeriodicalId":15789,"journal":{"name":"Journal of Exposure Analysis and Environmental Epidemiology","volume":"7 3","pages":"267-78"},"PeriodicalIF":0.0,"publicationDate":"1997-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20190894","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The changing risk assessments for crystalline silica.","authors":"D F Goldsmith,&nbsp;J S Gift,&nbsp;L D Grant","doi":"","DOIUrl":"","url":null,"abstract":"","PeriodicalId":15789,"journal":{"name":"Journal of Exposure Analysis and Environmental Epidemiology","volume":"7 3","pages":"265-6"},"PeriodicalIF":0.0,"publicationDate":"1997-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20190893","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ambient PM10 emissions: contributions and impact on silica emissions.","authors":"R Ruble,&nbsp;D F Goldsmith","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>This paper reviews the ambient air literature and discusses the link between particulate matter with an MMAD < or = 10 micrograms (PM10) emissions and estimates of silica particulate concentrations. Silica appears to represent a range of 0.4-21% of PM10 emissions, although this estimation needs more research (including direct measurements) to contribute to increased confidence in the methodology.</p>","PeriodicalId":15789,"journal":{"name":"Journal of Exposure Analysis and Environmental Epidemiology","volume":"7 3","pages":"327-44"},"PeriodicalIF":0.0,"publicationDate":"1997-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20188895","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evidence for silica's neoplastic risk among workers and derivation of cancer risk assessment.","authors":"D F Goldsmith","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Although there has been debate in the medical community about silica's carcinogenicity since the 1930s, only in the past decade have there emerged scientific data supporting a causal association between industrial silica exposure and lung cancer. This paper examines the evidence for the association, with a particular focus on those studies appropriate for cancer risk assessment. The cancer risk extrapolations from epidemiology studies suggest that the levels of risks are approximately two factors less than that derived from animal studies. Additional research is needed to provide a stronger basis for the extrapolations so that policy makers can have more confidence in their estimates.</p>","PeriodicalId":15789,"journal":{"name":"Journal of Exposure Analysis and Environmental Epidemiology","volume":"7 3","pages":"291-301"},"PeriodicalIF":0.0,"publicationDate":"1997-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20188890","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Uptake and decay of volatile organic compounds at environmental concentrations: application of a four-compartment model to a chamber study of five human subjects.","authors":"L A Wallace,&nbsp;W C Nelson,&nbsp;E D Pellizzari,&nbsp;J H Raymer","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Five subjects were exposed to nine volatile organic compounds (VOCs) at concentrations that can be encountered in everyday life. Breath samples were collected during a 10-h uptake phase and a 24-h decay phase. It was possible to determine four distinct slopes in the decay curve for each chemical. The distribution in the body and residence times in different tissues were calculated using a linear four-compartment mass-balance model. The model was used to predict breath concentrations for two subjects in a second chamber experiment including the same nine VOCs, representing three chemical classes (aromatic, aliphatic, and chlorinated compounds). Predicted values were generally within 25% of those observed, suggesting that the model parameters calculated here could be useful in estimating exposure and body burden to other VOCs in these three classes. Median residence times for the nine VOCs ranged from 3-12 min for compartment 1 (metabolizing); 0.3-2 h for compartment 2; 2-5 h for compartment 3; and 1-4 d for compartment 4. The fraction of the parent compound exhaled at equilibrium was estimated to range from 0.06-0.16 for four aromatic compounds and decane; 0.22-0.23 for trichloroethylene and dichloromethane; 0.35 for hexane; and 0.88 for 1,1,1-trichloroethane. Limited blood measurements were obtained for six of the nine VOCs in two subjects simultaneously with the breath samples over four-hour decay periods. Blood/breath ratios agreed well between the two subjects, but were higher than human blood/air partition coefficients reported in subjects exposed to high concentrations. This observation is consistent with results from other studies at relatively low concentrations.</p>","PeriodicalId":15789,"journal":{"name":"Journal of Exposure Analysis and Environmental Epidemiology","volume":"7 2","pages":"141-63"},"PeriodicalIF":0.0,"publicationDate":"1997-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20131406","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparative evaluation of methods for estimating potential human exposure to ozone: photochemical modeling and ambient monitoring.","authors":"P G Georgopoulos,&nbsp;V Purushothaman,&nbsp;R Chiou","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Photochemical modeling and ambient monitoring of ground-level ozone concentrations provide two alternative/complementary methods for calculating potential population exposure estimates. A comparative evaluation of these methods was undertaken over a study area comprised of the entire state of New Jersey and neighboring parts of Delaware, Maryland, Pennsylvania, and New York. Kriging, a geostatistical interpolation technique, was used for the interpolation of hourly ozone data from 38 air quality monitoring stations operating within the study area, to derive concentration fields for the entire domain. The Urban Airshed Model (UAM-IV), a comprehensive photochemical grid-based model, was then used to calculate the same concentrations from emissions and meteorology inputs. Concentration fields, thus developed, were linked with corresponding population data to calculate potential population exposure estimates to outdoor ozone (Ep.o). The adequacy of kriging as an interpolation technique was evaluated by comparing Ep.o estimates derived via photochemical UAM modeling with those calculated by using concentrations obtained from kriging UAM-calculated values at the locations of the monitoring stations. In general, UAM was found to predict higher Ep.o compared to those derived by kriging observations. In order to test the robustness of the interpolation methodology with respect to assumptions of statistical correlation, two different semivariogram models, spherical and exponential, were used for kriging. Application of the different semivariograms yielded almost identical Ep.o patterns.</p>","PeriodicalId":15789,"journal":{"name":"Journal of Exposure Analysis and Environmental Epidemiology","volume":"7 2","pages":"191-215"},"PeriodicalIF":0.0,"publicationDate":"1997-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20131412","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}