Abstract  BACKGROUND: Millions of people worldwide are exposed to arsenic-contaminated water. In the largest city in northern Chile (Antofagasta) >250,000 people were exposed to high arsenic drinking water concentrations from 1958 until 1970 when a water treatment plant was installed. Because of its unique geology, limited water sources, and good historical records, lifetime exposure and long-term latency patterns can be assessed in this area with better accuracy than in other arsenic-exposed areas worldwide. METHODS: We performed a population-based case-control study in northern Chile from October 2007 to December 2010 involving 232 lung and 306 bladder cancer cases and 640 age- and gender-matched controls, with detailed information on past exposure and potential confounders, including smoking and occupation. RESULTS: Bladder cancer odds ratios for quartiles of average arsenic concentrations in water before 1971 (<11, 11-90, 91-335, and >335 µg/L) were 1.00, 1.36 (95% confidence interval, 0.78 to 2.37), 3.87 (2.25 to 6.64), and 6.50 (3.69 to 11.43), respectively. Corresponding lung cancer odds ratios were 1.00, 1.27 (0.81 to 1.98), 2.00 (1.24 to 3.24), and 4.32 (2.60 to 7.17). Bladder and lung cancer odds ratios in those highly exposed in Antofagasta during 1958-70 but not thereafter were 6.88 (3.84 to 12.32) and 4.35 (2.57 to 7.36), respectively. Conclusions and Impact: The lung and bladder cancer risks that we found up to 40 years after high exposures have ended are very high, and suggest that prevention, treatment, and other mortality reduction efforts in arsenic-exposed countries will be needed for decades after exposure cessation.

Abstract  Background Person-years analysis is a fundamental tool of occupational epidemiology. A life table analysis system (LTAS), previously developed by the National Institute for Occupational Safety and Health, was limited by its platform and analysis and reporting capabilities. We describe the updating of LTAS for the Windows operating system (LTAS. NET) with improved properties.

Software Development Process A group of epidemiologists, programmers, and statisticians developed software, platform, and computing requirements. Statistical methods include the use of (indirectly) standardized mortality ratios, (directly) standardized rate ratios, confidence intervals, and P values based on the normal approximation and exact Poisson methods, and a trend estimator for linear exposure-response associations.

Software Features We show examples using LTAS. NET to stratify and analyze multiple fixed and time-dependent variables. Data import, stratification, and reporting options are highly flexible. Users may export stratified data for Poisson regression modeling.

Conclusions LTAS. NET incorporates improvements that will facilitate more complex person-years analysis of occupational cohort data. Am. J. Ind. Med. 54: 915-924, 2011. Published 2011. This article is a U. S. Government work and is in the public domain in the USA.

Abstract  A study of the incidence of pleural mesothelioma in residents of New Caledonia was conducted. All cases of primary pleural mesothelioma diagnosed in New Caledonia from 1978 through 1987 were reviewed in an attempt to identify any occupational or environmental factors. The incidence rates were compared with those of five cancer registries: Bas-Rhin, France 1978 to 1981; Doubs, France 1978 to 1982; England and Wales 1979 to 1982; New York State 1978 to 1987; and New South Wales, Australia 1978 to 1982. Twelve pleural mesothelioma cases, nine males, were diagnosed in New Caledonia during the study period. The age at diagnosis ranged from 31 to 79 years. Eight cases occurred in Melanesian subjects. One case was an Asian, two were Caucasians, and one was Wallisian. Three cases had been employed in the nickel mining industry on New Caledonia. The other cases had occupational contact with mines either personally or through their families. All cases had spent some time living in rural areas. The total number of cases and the number of cases among the Melanesians were significantly higher than expected. The risk was two to five times that indicated by the cancer registries. The authors conclude that an excess of pleural mesothelioma has been detected among the residents of New Caledonia. The excess cannot be attributed to occupational or geographical factors. The excess risk may reflect low exposure to an as yet unidentified agent.

Abstract  Male hamsters received chronic exposures to a respirable aerosol of Canadian chrysotile asbestos 7 hours per day, 5 days per week. Half of the animals were also exposed for 10 minutes to cigarette smoke three times per day, 5 days per week, for the duration of their life span. The other half of the animals received sham smoke exposures. Another group of hamsters served as controls. Half of the controls received smoke exposures, the other half received sham exposures. Asbestos exposure resulted in earlier and more severe lung lesions than in identical groups of concurrent experiments, which had received life span exposures to aerosols of nickel-oxide and cobalt-oxide, or which were treated with diethylnitrosamine. Asbestosis developed in all animals and forced discontinuation of the asbestos exposures after 11 months. Of 12 lung adenomas found in 510 hamsters, ten occurred among the 102 animals of the asbestos exposed groups, indicating an early neoplastic response. However, perhaps on account of their significantly shorter life span due to asbestosis, the incidence of laryngeal lesions and of malignant tumors was significantly lower in the asbestos plus smoke exposed group than in the control group having received smoke exposures. Neither a carcinogenic effect of asbestos nor a cocarcinogenic effect of cigarette smoke was observed. Cigarette smoke inhalation resulted in significantly lower mean body weights of the smoke exposed groups.

Abstract  BACKGROUND: More than 10 years have passed since the terrorist attack on the New York City World Trade Center on September 11, 2001. It is well known that long-term carcinogenic bioassays on rodents can predict the potential carcinogenic effects of chemical and physical agents for humans.

OBJECTIVE: A life-span carcinogenicity bioassay was conducted on Sprague-Dawley rats at the CMCRC of the Ramazzini Institute to test the potential carcinogenic effects of settled dust collected at the WTC immediately after the terrorist attack.

METHODS: The WTC material tested is a complex mixture of coarse particles (95%) contain pulverized cement, glass fibres, asbestos, lead, polycyclic aromatic hydrocarbons (PAH(S) ), polychlorinated biphenyls (PCB(S) ) and polychlorinated furans, and dioxin. The test matter was suspended in sterile saline and administered by intratracheal instillation (IT) to 8-week-old Sprague-Dawley rats (100 animals/sex), 3-4 days/week for 4 weeks. A group of 200 male and female rats served as controls. The animals were kept under observation until natural death.

RESULTS: Histopathological evaluation of the lungs (target organ) of instilled control and treated male and female rats, did not show any significant increased incidence of lung tumors. Two hemangiomas (one with endothelial atypia) and one hemangiosarcoma were found in the lungs of treated males. Moreover a modest increased incidence of terminal bronchiolar hyperplasia (TBH) and squamous metaplasia occurred in the lung of treated males and females compared to the controls.

CONCLUSION: Hemangioma and hemangiosarcoma are extremely rare tumors in the lung of our colony and we believe they are caused by WTC dust.

Abstract  Several types of zeolite materials were synthesized using industrial asbestos wastes, which were of different natures and origins: Cords (S1) and Plates (S2) of thermal insulation, but also a specimen of the Jussieu building in Paris (S3). This revaluing process includes two steps. Firstly, the alteration of the wastes into amorphous silica is achieved by acid leaching with H(2)SO(4) at different concentrations for variable periods of time. Preliminary characterizations performed on the treated materials revealed the presence of amorphous compounds that confirmed the structural damage of asbestos fibers. Secondly, zeolite materials such as Na-A (LTA), Na-X (FAU), silicalite-1 (pure silica MFI zeolite) and BEA are synthesized using the resulting amorphous compound as a unique silica source. The obtained materials were fully characterized by usual techniques. Amorphous silica derived from asbestos wastes is found to be an economical and highly reactive source for the zeolite synthesis. (C) 2009 Elsevier Inc. All rights reserved.

Abstract  OBJECTIVES: The aim of the study was to determine the causes of impairment of ventilatory function and diffusing capacity in smoking asbestos-exposed workers (N=590) showing radiological pleural thickenings or pulmonary fibrosis.

METHODS: High-resolution computed tomography (HRCT) and spirometry were performed, and diffusing capacity was measured. The workers were divided into five groups based on the HRCT scoring: pleural disease (N=190), pulmonary fibrosis (N=68), emphysema (N=148), combined fibrosis and emphysema (N=74), and marked adhesions (N=110). The graded lung function impairment was compared between the groups.

RESULTS: Moderate impairment of forced expiratory volume in 1 second [odds ratio (OR) 2.72, 95% confidence interval (95% CI) 1.31-5.57] and forced vital capacity (OR 2.81, 95% CI 1.05-6.89) was associated with the persons with combined fibrosis and emphysema. Marked impairment of diffusing capacity was associated with the combined fibrosis and emphysema (OR 4.94, 95% CI 2.48-9.77) but not with pleural disease (OR 0.21, 95% CI 0.09-0.45) or pulmonary fibrosis (OR 0.36, 95% CI 0.08-1.05). For the persons with combined fibrosis and emphysema, the mean fibrosis score did not differ between normal, slightly reduced, or markedly reduced diffusing capacity, but the emphysema score was significantly higher for the patients with marked impairment than for those with normal diffusing capacity (P < 0.01).

CONCLUSIONS: Different profiles of asbestos- and smoking-induced pulmonary or pleural disease were found. The results indicate that the most important factor determining the degree of functional impairment in smoking asbestos-exposed workers is the presence of pulmonary emphysema.

Abstract  This study aimed to determine the prevalence of respiratory morbidity among asbestos-exposed ironworkers and to determine the relationship between respiratory morbidity indices and length of exposure. A medical screening provided information on chest radiographic abnormalities, pulmonary function, rales, finger clubbing, and respiratory symptoms for 547 asbestos-exposed ironworkers. Union pension records furnished data on length of exposure. The study group exhibited on increased prevalence of small irregular opacities, pleural plaques, and pleural thickening on chest x-ray; reduced FEF 25-75; rales; and respiratory symptoms. After controlling for the effect of cigarette smoking and age, years since joining the ironworkers union were significantly associated with profusion, pleural thickening, pleural plaques, rales, percent predicted FVC, reduced FVC, reduced FEV1, reduced FEV1/FVC, and dyspnea grades I, II, III, and IV.

Abstract  To determine the nature of respiratory functional impairment caused by asbestos-induced visceral pleural fibrosis (VPF) and to discover which pulmonary physiological variable best reveals it, we examined 59 asbestos-exposed construction workers having asbestos-related changes on chest radiographs. Computed tomography scans of the thorax were also performed. Visceral pleural fibrosis was diagnosed in 29 subjects: seven had only VPF, 17 had VPF and pleural plaques, and five had VPF, plaques, and asbestosis. In subjects without VPF, 23 had plaques, six had plaques and asbestosis, and one had only minor fibrotic parenchymal changes insufficient for a diagnosis of asbestosis. Flow-volume spirometry, body plethysmography, static and dynamic compliance, and pulmonary diffusing capacity for carbon monoxide were measured. The subjects with VPF had significantly lower static (p = 0.005) and dynamic (p = 0.007) compliance values than those without. Other respiratory function variables failed to show any significant differences. We conclude that the measurement of static and dynamic compliance is a useful method in assessing pulmonary function impairment caused by visceral pleural fibrosis.

Abstract  Pulmonary function tests have been conducted on 155 asbestos workers and 130 referents. It was found that the lung function impairment in asbestos workers is predominantly a restrictive ventilatory defect appearing even when radiographic changes are not detectable. There was, however, no evidence of airway obstruction. As the disease progressed, all the pulmonary function indices, including vital capacity (VC), forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1.0), maximal ventilation volume (MVV), total lung capacity (TLC), and pulmonary diffusing capacity (DLCO), were reduced dramatically, with the exception of FEV1.0/FVC(%). It is suggested that both radiographic examination and pulmonary function tests should be used as early detection measures of asbestos-induced lung disorders. VC, FVC, and FEV1.0 are the simplest, most reproducible, and most valid indices for the health surveillance of asbestos workers, while the FVC test is the most valuable for epidemiologic study. With stepwise regression analysis a quantitative relationship between dust exposure and pulmonary function was demonstrated. There was no significant difference in the small airway function of the exposed workers and the referents. Further study is needed to investigate the possibility of asbestos-induced small airway obstruction and to estimate the roles played by cigarette smoking and air pollution.

Abstract  BIOSIS COPYRIGHT: BIOL ABS. RRM ABSTRACT HUMAN EPIDEMIOLOGY

Abstract  OBJECTIVE: Increased availability and technical improvements of computed tomographic (CT) scanning encourages its use for detecting asbestos-related disease. We compared low-dose scans and x-ray films in 2760 workers potentially exposed to asbestos, to assess their ability to detect interstitial lung disease (ILD) and pleural thickening (PT).

METHODS: A total of 2760 nuclear workers received radiography and CT scanning (2006 to 2009). X-ray films were read by a B reader for ILD and PT and CT scans by a thoracic radiologist, using a protocol for nodules, ILD, and PT.

RESULTS: Of the 2760 workers, 271 showed circumscribed PT on CT scans, and 73 on x-ray films, 54 (74%) of which were confirmed on CT scans; 76 showed ILD on CT scans, and 15 on x-ray film, 10 (67%) of which were confirmed on CT scans.

CONCLUSIONS: Radiographic readings of PT and ILD were generally confirmed on CT scans. Computed tomographic scans detected three to five times more cases; the majority were minor.

Abstract  Long term inhalation in Wistar-rats, intrapleural injection in Wistar-rats, and injection into the tracheal lobe of sheep were used to determine the effects of phosphorylation of chrysotile (12001295) on its subsequent pleuropulmonary effects. Studies were also performed using native, untreated, chrysotile fibers. Phosphorylated chrysotile (chrysophosphate) or chrysotile was administered to sheep by bronchoscopic catheterization and slow infusion in the tracheal lobe. Rats were administered chrysotile, chrysophosphate or titanium-oxide by intrapleural injection. For the inhalation study, rats were exposed whole body for 5 hours/day, 5 days/week for 24 months to chrysotile, chrysophosphate or titanium-oxide. Chrysophosphate and chrysotile exhibited similar pulmonary fibrogenicity in sheep and rats in these studies. During the final 6 months of the intrapleural rat study, mortality was higher in the chrysotile group and related to histologically identified mesotheliomas. The incidence of such tumors was lower in the chrysophosphate group, but not significantly so. The long term inhalation study did not show less pulmonary carcinogenicity for chrysophosphate. Squamous carcinomas occurred with greater frequency in the chrysophosphate than chrysotile exposed animals. The particular surface modifications induced by chrysophosphate treatment were ineffective in reducing the long term fibrogenicity and carcinogenicity of chrysotile in these animals.

Abstract  In response to a request from OSHA, possible hazardous working conditions at the McGraw-Edison (SIC-3612) facility located in Canonsburg, Pennsylvania were investigated. The company produced large power transformers plus various sizes of power circuit breakers. Exposures to welding fumes, high voltage electricity, paint solvent vapors, noise, and transformer oils were possible. Past exposures to oils containing polychlorinated-biphenyls (1336363), and asbestos (1332214) were possible. A group of 58 employees was examined in an attempt to verify possible clustering of cancer cases. Of the original 58, no records were found for three, and 18 individuals had died but had never had cancer. The remaining 37 were all confirmed cancer cases covering 13 different types. An apparent clustering of cancer in recent years was demonstrated. All but one case occurred in white males between the ages of 43 and 69 years. Lung cancer was the most common type, 16 of the 37 cases. The authors conclude that, compared with the general population, lung cancer was occurring probably at no greater rate among these employees than in the general population. No evidence was found to associate causally the number of cancer cases among the workers and any occupational exposures they may have been experiencing at this facility. The authors recommend that a thorough industrial hygiene survey be made at this facility.

Abstract  Mineralogical analyses of the saprolitic laterite material have been characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier transform infrared (FIR) spectroscopy, thermal analysis, scanning electron microscope (SEM) and energy dispersive X-ray analysis (EDAX). Results showed that the saprolitic laterite material consists mainly of nickel-substituted lizardite showing the pebble-like morphology and traces of magnetite and phlogopite. Leaching results showed that as much as 84.8% nickel could be leached under the experimental conditions of 10% (v/v) H(2)SO(4), 90 degrees C reaction temperature, leached within 5 min, particle size d(50) (=) 25 mu m, stirring at 500 rpm and liquid to solid ratio 3:1. The kinetics of nickel and magnesium leaching from the saprolitic laterite material have been investigated in a mechanically stirred reactor and the activation energies were determined to be 53.9 kJ mol(-1) for nickel and 59.4 kJ mol(-1) for magnesium respectively, which are characteristic for a chemical reaction controlled process. The similarity of the activation energies of nickel and magnesium leaching from the saprolitic laterite material by sulphuric acid means that nickel in lizardite is loosely bound within the octahedral layer and almost all of the nickel could be leached simultaneously with magnesium but without complete decomposition of the silicate structure. (C) 2009 Elsevier Ltd. All rights reserved.

Abstract  A preliminary study at the Institut National de l'Environnement Industriel et des Risques (INERIS] examined the dissolution of three man-made vitreous fiber samples (glasswool, rockwool, glass microfibers: JM 100) after intraperitoneal injections in male Wistar rats. The chemical composition of the original fibers was determined by inductively coupled plasma spectrometry (ICP). The urine of the rats was collected at fixed times between day 1 and day 204, and the ICP was used to look for elements known to be present in the original fibers. At day 204, a piece of omentum was removed at autopsy, ashed and analyzed by energy dispersive X-ray analysis (EDXA) to identify the elements remaining in the fibers. Silicon and aluminium were retained in the fibers from all samples at day 204. Losses in calcium, sodium, magnesium, and sulfur were observed, but these elements were not studied in the urine samples because they are naturally present in relatively high concentrations in rat cells and biological fluids. Although there was a loss of zinc from the glass microfibers, no corresponding difference was observed between the zinc levels excreted by the treated animals and by the controls. Similarly, despite the loss of manganese from the rockwool fibers al day 204, none was detectable in the urine samples. Titanium, present at the 0.3% level in rockwool, was not detectable by EDXA at day 204, but small quantities were detected in the first 2 weeks in the urine samples of rats treated with rockwool. The barium content of the retained glass microfibers (JM 100) had decreased at day 204, and this element was detectable in the corresponding urine samples, It was considered that Ti and Ba could be suitable biomarkers of exposure to rockwool and glass microfibers (JM 100).

Abstract  BIOSIS COPYRIGHT: BIOL ABS. RRM COPPER LEAD ASBESTOS ALUMINUM ENVIRONMENTAL TOXICOLOGY

Abstract  In a 1990-1996 case-control study in western Germany, the authors investigated lung cancer risk due to exposure to residential radon. Confirmed lung cancer cases from hospitals and a random sample of community controls were interviewed by trained interviewers regarding different risk factors. For 1 year, alpha track detectors were placed in dwellings to measure radon gas concentrations. The evaluation included 1,449 cases and 2,297 controls recruited from the entire study area and a subsample of 365 cases and 595 controls from radon-prone areas of the basic study region. Rate ratios were estimated by using conditional logistic regression adjusted for smoking and for asbestos exposure. In the entire study area, no rate ratios different from 1.0 were found; in the radon-prone areas, the adjusted rate ratios for exposure in the present dwelling were 1.59 (95% confidence interval (Cl): 1.08, 2.27), 1.93 (95% Cl: 1.19, 3.13), and 1.93 (95% Cl: 0.99, 3.77) for 50-80, 80-140, and >140 Bq/m(3), respectively, compared with 0-50 Bq/m(3). The excess rate ratio for an increase of 100 Bq/m(3) was 0.13 (-0.12 to 0.46). An analysis based on cumulative exposure produced similar results. The results provide additional evidence that residential radon is a risk factor for lung cancer, although a risk was detected in radon-prone areas only, not in the entire study area.

Abstract  This paper reviews the epidemiologic evidence of cancer risks among workers in aluminum reduction plants with emphasis on associations with specific work areas and exposures. Studies of workers manufacturing carbon products outside the aluminum industry were also reviewed since the work environment is similar to that encountered in the carbon area of aluminum plants. We obtained 22 reports from references cited in earlier reviews, through compact disc literature search 1980-1990, and from the Nordic Aluminum Industry's Secretariat for Health, Environment and Safety. Six reports were excluded because the material was included in later studies or because a critical evaluation was impossible. This left 16 publications from 11 separate studies. Work in potrooms with Söderberg electrolytic cells was associated with increased risk of bladder cancer, and the increase was correlated to duration of tar exposure. There was a suggestion of increased risk of leukemias and pancreatic cancers in potroom workers, and of kidney and brain cancers without any clear association with specific exposures or work areas. Singular results showed associations between lung cancer risk and tar exposure in Söderberg plants, and between lung cancer and work in prebake or carbon plants, but interpretation was limited by inadequate data on smoking and asbestos exposure, and by problems connected with the choice of reference populations in these studies.

Abstract  The Los Santos scheelite skarn deposit, located in the province of Salamanca, northwest Spain, occurs in meter-thick strata-bound but irregular lenses of <= 1 km in length and contains a current total resource of 3.09 million metric tons (Mt) with an average grade of 0.54 percent WO(3). It was produced by the metasomatic alteration of Upper Vendian-Lower Cambrian metasedimentary rocks and granitic rocks located in the western part of the Avila batholith plutonic complex. Magmatic activity in the Los Santos zone comprises two intrusions, including biotite monzogranite (281-280 +/- 6 Ma, granite 1) and porphyritic biotite granodiorite-monzogranite (270-269 +/- 6 Ma, granite II). The mineralized skarn distributed close to the intrusions occurred in two main stages (I) prograde skarn, and (II) retrograde alteration of the stage I skarn. The prograde exoskarn is made up of a thick, almost monomineral mass of hedenbergite (Hd(82-87)), accompanied by grossular (Grs(53-73)) and scheelite rich in Mo (Sch I). Early mineralization is associated with granite I; thus, it is possible to recognize an endoskarn of calcic plagioclase and clinopyroxene developed over aplitic granite. The stage I skarn formed from H(2)O-rich (X(CO2) <0.1) with an upper temperature limit of 630 degrees C at 0.18 to 0.2 GPa, a log f(O2) of -21, and log f(S2) ranging from -9.7 to -5.0. After the emplacement of granite II there was a late event characterized by pegmatites, dike swarms, breccia pipes, and intense fracturing associated with the retrograde alteration, which was superimposed on massive skarn. The retrograde skarn has a complex paragenesis that can be divided into two substages. In the first, subcalcic garnet formed, associated with the leaching of early scheelite and the precipitation of late scheelite poor in Mo (Sch II). There is also ferroactinolite, together with important amounts of anorthite, zoisite, apatite, titanite, quartz, and sulfides, mainly pyrrhotite. The first use of -23 and log f(S2) ranging from -10 to -7. The data on fluid inclusions indicate that fluid boiling and immiscibilty, at temperatures between 439 degrees and 405 degrees C and pressures ranging from 0.1 to 0.042 GPa, was a possible mechanism in the Sch II and sulfide deposition during the first substage of the retrograde alteration of the skarn. The second substage is characterized by the formation of clinozoisite, prehnite, quartz, calcite, chlorite, white mica, zeolite, and mineral phases belonging to the Bi-Te-Ag-S-Au system. The mineral assemblages indicate that the f(O2) values are between -25.9 and -33.4 while log f(S2) ranges from -10.6 to -6.3 for T <300 degrees C. All the data suggest that the development of the Los Santos skarn represents the evolution of a magmatic-hydrothermal system. In this model, carbon-aqueous fluids would have been exsolved from the plutonic complex during its emplacement and crystallization. The gradual interaction of magmatic fluids at high temperatures with the graphitic rocks of the Schist-Greywacke Complex resulted in a reduction in ore fluids and higher CH(4)/CO(2) ratios. The fluid associated with the last substage of the retrograde alteration of the deposit belongs to the H(2)O-Nacl system and suggests and influx of a surface-derived fluid.

Abstract  During braking, both the rotor and pads experience wear, generating particles that may become airborne. In field tests, it is difficult to distinguish these particles from others in the surrounding environment, so it is preferable to use laboratory test stands to study the amount of airborne wear particles generated. The purpose of this work is to investigate the possibility of separate, capture, and analyze airborne wear particles generated by a disc brake in a disc brake assembly test stand. This test stand used allows the cleanliness of the air surrounding the test specimens to be controlled and thus the airborne portion of the wear particles to be studied separately. One pair each of low-metallic (LM) and non-asbestos organic (NAO) brake pads was tested against grey cast iron rotors. Before testing, the elemental contents of the brake materials were analyzed using glow discharge optical emission spectroscopy (GDOES). The concentration and size of airborne wear particles were measured online during testing. In addition, airborne wear particles were collected on filters during the tests and afterward analyzed using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The analyzed wear particles contained elements such as iron, titanium, zinc, barium, manganese, and copper. Both the low-metallic and non-asbestos organic type of brake pads tested display a bimodal size distribution with peaks at 280 and 350 nm. Most of the airborne particles generated have a diameter smaller than 2.5 mu m.

Abstract  The modification of the chemistry of asbestos chrysotile fibres (Mg3(Si2O5)(OH)4) after their ingestion by cultured cells has been studied. Two types of cells involved in asbestos related pulmonary disease were used, rabbit alveolar macrophages (AM), recovered by bronchoalveolar lavage, and pleural mesothelial cells (PMC) obtained from the rat parietal pleura. Chemical characterisation of intracellular fibres was performed on unstained ultrathin sections by electron probe microanalysis. The results showed a progressive leaching of Mg, characterised by a time dependent decrease of Mg/Si. AM were more efficient than PMC at leaching intracellular chrysotile fibres since it took longer to obtain the same proportion of leached fibres with PMC than with AM. As in vitro Mg-leaching can be obtained by acid treatment, chrysotile fibres were incubated, either untreated or pretreated with cell membranes, at pH 4 or 7 for various times. The data show that the kinetic of leaching by AM was comparable with leaching at pH 4. The leaching by PMC was of the same order as leaching at pH 7. When membranes were adsorbed on to the fibres, a delayed leaching was observed. The results indicate that the solubilisation of chrysotile by AM could be an intraphagolysosomal event due to a pH effect. With PMC, however, it is not possible to draw this conclusion since nothing is known about the intracellular pH.

Abstract  Worker exposures to asbestos (1332214), sodium-hydroxide (1310732), total welding fumes, and metal particulates were surveyed on August 12 and 24, 1982 at Drive Train Industries, Incorporated (SIC-3714), Denver, Colorado. The evaluation was requested by an employee representative on behalf of an unspecified number of workers. Personal and area air samples were analyzed, and noise levels were measured. One area air sample for nickel (7440020) exceeded the NIOSH standard of 0.015 milligrams per cubic meter. All other chemical and fiber exposures were within acceptable limits. Noise levels exceeded the NIOSH limit of 85 decibels relative to the A-weighted scale. The author concludes that a noise exposure hazard exists at this facility. He recommends improved noise engineering controls and implementation of a hearing protection and audiometric testing program.