Abstract  A method was developed to analyze metals in asbestos (1332214) samples by neutron activation. Samples of asbestos were dried at 100 degrees-C, cooled, and 100 milligram portions were sealed in silica ampules. Standards were also prepared in silica ampules, and both samples and standards were placed in aluminum cans. They were irradiated, weighed, sintered with sodium-peroxide, and dissolved in hydrochloric-acid. Chemical separation was carried out by means of hydroxide precipitation followed by anion exchange, and their radiation products were eluted. A gamma ray spectrometer was also used as a comparison to determine if the standards prepared by milling were different from the standard reference samples. The metals determined were chromium (7440473) (Cr), nickel (7440020), cobalt (7440484) (Co), iron (7439896) (Fe) and scandium (7440202) (Sc). No significant differences were detected in the milled and nonmilled standards. Several types of asbestos, Canadian chrysolite (12001295) and crocidolite (12001284) samples were analyzed using this method. The chrysolite samples had concentrations ranging from 1.8 to 5.0 percent Fe, 120 to 1200 parts per million (ppm) Cr, 39 to 110ppm Co, 550 to 2600ppm Ni, and 4.1 to 12.0ppm Sc. The African crocidolite samples had concentrations ranging from 20 to 26 percent Fe, 0.4 to 0.9ppm Co, and 0.04 to 0.6ppm Sc. The Cr content was less than 20ppm, and the Ni content was less than 100ppm. The authors conclude that these metals can be determined in asbestos samples with good sensitivity by neutron activation.

Abstract  The Doriri Creek (DC) Ni-Pd-Pt prospect was discovered in 1966 in the Papuan Ultramaflc Belt (PUB) in PNG. The DC was interpreted as a hydrothermal Ni accumulation. The DC is located in the southern proximity of Mt Suckling (similar to 180 km SE of Port Moresby), where local intrusive rocks are intermediate to acid dykes and small stocks, within the tec tonized contact zone of the Australian and Woodlark Plates. The active volcanoes of Mount Victory and Waiowa indicate recent thermal activity in the area. The Doriri Creek prospect is the result of episodic hydrothermal fluid flow running through the Doriri prospect, that resulted in Ni concentration of up to 1.55 wt.%, formed by alteration of an ultramafic unit of peridotites/pyroxenites within a Mg-rich gabbronorite envelope. Ni was concentrated in chlorite and serpentine group minerals in addition to Fe oxides, with a minor amount in pentlandite in locally sulfidic samples. Ore mineralogy is also associated with a high phosphorous content as apatite, that concentrates LREE (light rare earth elements). Palladium concentrations are up to 037 ppm. Platinum is present in concentrations up to 0.06 ppm within the ore. The alteration halo associated with Doriri Creek mineralization is similar to 100 m in width. Primary mineralogy comprises pyroxene, olivine and plagioclase, which have been altered extensively to amphibole and chlorite-serpentine group minerals. This halo is characterized by enrichments of U, K and W over background values. Local magnetite concentration is up to similar to 35% of whole rock, which is very pronounced in the sulfide rich area of the system. The top part of the DC system is overprinted by tropical weathering at metric scale, which displays LREE enrichment and positive Ce anomalies. The Papuan Ultramafic Belt is described as a highly prospective ground for hydrothermal Ni systems based on its availability of Ni, active thermal flow engines, and the geologic regional context dominated by mafic rock suites and the presence of carbonate/siliciclastic units. Crown Copyright (C) 2012 Published by Elsevier B.V. All rights reserved.

Abstract  The aim of this study was to determine the inorganic filler fractions and sizes of commercially alginates. The inorganic particles volumetric fractions of five alginates - Jeltrate(J), Jeltrate Plus(JP), Jeltrate Chromatic Ortho(JC), Hydrogum(H) and Ezact Krom(E) were accessed by weighing a previously determined mass of each material in water before and after burning samples at 450 degrees C for 3 hours. Unsettled materials were soaked in acetone and chloroform and sputter-coated with gold for SEM evaluation of fillers' morphology and size. The results for the volumetric inorganic particle content were (%): J - 48.33, JP - 48.33, JC - 33.79, H - 37.55 and E - 40.55. The fillers presented a circular appearance with helical form and various perforations. Hydrogum fillers looked like cylindrical, perforated sticks. The mean values for fillers size were (mu m): J - 12.91, JP - 13.67, JC - 13.44, E - 14.59 and H - 9 (diameter), 8.81 (length). The results of this study revealed differences in filler characteristics that could lead to different results when testing mechanical properties.

Abstract  BACKGROUND: A major French chlorine chemical plant (chlor-alkali process with diaphragm cell and manufacturing of organochlorine chemicals) has used or produced known or suspected carcinogenic compounds.

METHODS: A cohort study, based on the plant occupational health service and the regional cancer registry, analyzed the standardized incidence ratios of malignant tumors for the period 1979-2002. Individual exposures were estimated from workers' occupational histories in a dual division of jobs into 9 sectors and 115 workshops with known exposures.

RESULTS: Men (2,742) were followed, corresponding to 52,794 person-years. Primary tumors (304) were observed for 290 expected cases, a non-significant 5% excess. A significant excess was found of pleural mesothelioma and bladder cancer in employees hired before 1964.

CONCLUSION: Excesses of mesothelioma and bladder cancer were found, whereas there was no excess of hematopoietic cancers despite high benzene and dioxin exposures. Surprisingly, mesothelioma cases did not include workers who were the most exposed to asbestos.

Abstract  The role of occupational risk factors in oral and pharyngeal cancer is not well known and is possibly underestimated. This quantitative review summarizes epidemiological findings on exposure to asbestos, polycyclic aromatic hydrocarbons and solvents, and cancers of the oral cavity and pharynx.

A systematic literature search was performed. We analyzed 63 publications: 8 from case-control studies and 55 from cohort studies. For agents with at least five available studies with homogenous exposure, a series of meta-analyses was conducted to provide quantitative pooled estimates of risks, using random effect models.

Exposure to asbestos (meta-RR 1.25; 95% CI 1.10-1.42) and to polycyclic aromatic hydrocarbons (meta-RR 1.14; 95% CI 1.02-1.28) was found to be associated with oral and pharyngeal cancer risk. On the other hand, no association was found with exposure to solvents in general (meta-RR 0.98; 95% CI 0.77-1.23) but the strong heterogeneity between studies suggested differences in exposures. The small number of studies with homogeneous exposure did not allow meta-analyses for specific solvents.

Future investigations should overcome common weaknesses of past studies, in terms of sample size, characterization of exposure, and classification of cancer sites.

Abstract  The action of different concentrations of sodium chloride, benzocaine and clove oil in the survival of fingerling and juvenile tilapia (Oreochromis niloticus), chitralada lineage, was tested during 5 hours for transportation. A total of 1350 fingerlings were used (weight 9.74 +/- 0.04 g and length 6.79 +/- 0.01 cm) and 270 juveniles (average weight 29.6 +/- 0.06 g and length 11.52 +/- 0.01 cm). The fish were maintained without food for 24 hours in four 500L asbestos boxes with constant aeration. Subsequently, the fish were distributed in 54 5 L plastic bags and maintained in a solution of sodium chloride at a concentration of (0; 4; 8 g/L), benzocaine (0; 20; 40 mg/L) and clove oil (0; 2; 5 mg/L). A randomized block experimental design was used with three replications, in multi-factorial arrangements, with three factors: substances, fish and different concentrations for each substance used. Dissolved oxygen, temperature, pH, salinity and ammonia were measured at the beginning of the experiment and the fish glucose at the end of the experiment. The largest glucose levels were detected in the juveniles maintained in water with clove oil and sodium chloride. Significant differences were not observed in the survival among types of fish and substances. However, the doses used of sodium chloride and benzocaine caused significant differences in the survival rate. There was low fingerling survival with 0 g/L of sodium chloride that differed from the doses 4 and 8 g/L. The clove oil presented similar results at all the different doses and all the substances on the glucose rates. Survival was satisfactory at the end of the experiment, with a general average of 97.26%, showing that the three substances can be used to transport fingerlings and juveniles during 5 hours. Sodium chloride is recommended because it was the most cost-effective.

Abstract  This work aimed at elucidating on the micromorphology and microchemistry of serpentine minerals occurring in the Moshaneng Serpentinite associated with the Neo-Archaen Taupone Dolomite Group, Botswana. Samples obtained from Moshaneng Serpentinite abandoned mine were analysed by environmental scanning electron microscopy (ESEM) and energy dispersive X-ray (EDX) spectrometry in order to identify and characterise their mineral constituents. The micromorphology of the samples depicted fine grained platy lizardite and tubular fibre veins of chrysotile. Results of microchemical analyses indicated that the samples consisted of MgO and SiO2 in acceptable wt %ages for serpentine. Varied wt %ages of Al2O3, Fe2O3, CaO, SO2, Cl2O, K2O, TiO2, and MnO in the samples could be due to isomorphic substitution of Al and Fe in the octahedral and tetrahedral sheets of serpentine. Mineralization in Moshaneng Serpentinite is considered to have been of two phases: the first being the formation of lizardite through isochemical serpentinization of olivine; and the second being the mineralization of chrysotile by allochemical serpentization of lizardite. Because chrysotile is the dominant asbestos mineral in the Moshaneng Serpentinite, aspects of environmental and human health as well as rehabilitation of the abandoned mine should be addressed with exigency.

Abstract  The extent of airborne release of fibers from asbestos substitute materials used in high friction products was evaluated. Dust was collected after rubbing brake and clutch linings containing man made mineral fibers and Kevlar with emery paper. Four air samples were collected and examined by transmission electron microscopy (TEM) and energy dispersive X-ray analysis. At x3000, TEM examination showed Kevlar fibers in the respirable range which were capable of deep penetration into the lungs. Of the fibers, 96% had diameters below 2.5 microns and all were more than 80 microns in length. Significant amounts of dust were produced by the clutch plates; samples included carbon (7440440) and inorganic fibers of silicon (7440213) (Si), aluminum (7429905) (Al), calcium-sulfate (7778189), and calcium (7440702) (Ca), as well as some metallic fibers like copper (7440508). The truck brake shoes for trucks had inorganic fibers containing Si, Ca, Al, sulfur (7704349), magnesium (7439954), sodium (7440235), and a small amount of chrysotile (12001295) was also found, while Kevlar was not detected. The majority of car brake shoe fibers were glass. The authors conclude that replacement fibers generate substantially fewer fibers than asbestos, but that the size and inertness of Kevlar fibers may indicate the potential for pulmonary retention.

Abstract  Induction of matrix metalloproteinase, tissue inhibitors of metalloproteinase, and extracellular matrix mRNA expression by mineral fibers and cigarette smoke was studied in rats. Male Wistar-rats were instilled intratracheally with 2 milligrams of chrysotile (12001295) or aluminum-silicate (12141467) ceramic fibers (RCFs) after which they were sham exposed or exposed to sidestream cigarette smoke 5 days per week for 4 weeks. After exposure the rats were killed and their lungs removed. Some lungs were examined for histological changes. The RNA was extracted from other lungs and analyzed for mRNA coding for matrix metalloproteinase-1 (MMP-1), matrix metalloproteinase-2 (MMP-2), tissue inhibitors of MMP-1 (TIMP-1) and MMP-2 (TIMP-2), and type-I and type-IV collagen by a reverse transcription/polymerase chain reaction assay. All treatments significantly increased MMP-1 mRNA expression. The increase induced by chrysotile plus cigarette smoke was additive. Neither chrysotile, the RCFs, nor cigarette smoke alone affected MMP-2 mRNA expression. Combined exposure to chrysotile plus cigarette smoke or RCFs plus cigarette smoke significantly increased the level of MMP-2 mRNA expression. TIMP-1 mRNA expression was not detected in control, chrysotile or RCF exposed lungs. Cigarette smoke alone and cigarette smoke plus chrysotile induced TIMP-1 MRNA expression. TIMP-2 mRNA expression was not induced by either RCFs or chrysotile. Cigarette smoke significantly decreased TIMP-2 mRNA expression. This effect was not altered by RCF nor chrysotile coexposure. Neither RCFs nor chrysotile increased type-I collagen mRNA expression. Cigarette smoking decreased type-I collagen mRNA expression. Expression of type-IV collagen mRNA was not detected in any of the lung tissue samples. Foreign body giant cells and mononuclear cell infiltration around bronchioles were observed in lung tissues from chrysotile and chrysotile plus cigarette smoke exposed rats. No treatment related histopathological changes were seen in lung tissues from the other groups. The authors conclude that MMPs and TIMPs may be associated with remodeling of lung tissues induced by exposure to mineral fibers and cigarette smoke.

Abstract  Associations between inorganic fiber burdens and job category in the lungs of industrial workers were examined. Lung tissue sections were collected from 21 workers employed in gold, zinc, and copper mining, 18 iron foundry workers, 22 noniron foundry workers, four welders, three sandblasting workers, four construction workers, three technical or professional workers, seven workers in 'miscellaneous trades', 13 former asbestos (1332214) workers with mild asbestosis, and 20 persons from the general population (controls). The tissue samples were digested in aqueous sodium-hypochlorite. After drying, the digests were prepared for analysis for quartz (14808607) and other elements by transmission electron microscopy and energy dispersive spectroscopy. The quartz analyses were also performed by X-ray diffraction analysis. The highest quartz concentrations varied from 0.69 to 3.90 million particles per milligram dry lung tissue (mp/mg) and were found in tissues from the miners, iron foundry, and sandblasting workers. Lung quartz burdens in the workers in the other occupations varied from 0.05 to 0.65mp/mg, the highest concentrations in these groups being found in the welders and technical and professional personnel. The quartz concentrations in the asbestos workers and controls averaged 0.40 and 0.23mp/mg, respectively. High levels of metallic particles were found in the lungs of welders and iron foundry workers, averaging 6.13 and 1.10mp/mg, respectively. The particles consisted primarily of aluminum (7429905), nickel (7440020), manganese (7439965), cadmium (7440439), and chromium (7440473). When stratified according to fiber characteristics, the highest concentrations of long fibers were found in noniron foundry workers and asbestos workers. High concentrations of ferruginous bodies were also found in these groups. The noniron foundry workers had been exposed to ceramic and asbestos fibers. The authors conclude that the composition of the particles found in the lungs of these workers can be explained on the basis of their work histories. The broad range of particle types identified demonstrate the complexity of trying to determine disease origins in these occupational settings.

Abstract  Exposures to potentially confounding chemical and physical agents were estimated as part of a study on the relationship between cancer and chronic exposure to electric and magnetic fields among electrical workers. Confirmed or suspected carcinogen (CSC) exposure estimates for 64 job categories from 1950 through 1990 were presented for the Hydrouebec electrical utility. A list associating 57 tasks and general exposures with exposure to one or more CSC was provided. Interviews of foremen and senior workers identified 24 CSC and 15 surrogate exposures present at the facility. Long term exposure was limited to skin exposure to dielectric oils. Acute inhalation exposure to asbestos (1332214), carbon dust, chromium (7440473), nickel (7440020), and methylene-chloride (75092) and skin exposure to mineral oils, polychlorinated biphenyls (PCB) and sunlight were considered for equipment electricians and mechanics in generation and substation repair and maintenance. Regular dermal exposure to wood preservatives was seen for distribution linemen. Exposures for other trades were considered low or rare. No chronic exposures were found to exceed threshold limit values (TLV). Exposure data on 11 CSCs identified in the OSHA National Health Sampling Results as well as surrogate exposure were summarized. Estimated exposures to CSCs classified by job category and time weighted average inhalation exposure were provided. Exposures to specific agents such as asbestos, dielectric oils and PCBs, diesel and gasoline exhaust, herbicides, soldering and welding fumes, solvent use, paint, and wooden poles and wood treatment, were discussed. Activities involving acute exposure to asbestos included cutting/removing gaskets, installing or removing asbestos wrapping, brake work on vehicles or turbine alternators, and working with asbestos blankets, panels or tiles. Dielectric oils and PCBs were the most common exposures, with 21 trades having regular skin contact. The authors conclude that long term exposure rarely exceeded 25% of the TLV for a CSC.

Abstract  The purpose of this survey was to evaluate the effects of smoking and occupational exposures on the decline in forced expiratory volume in one second (FEV1), and the presence of airflow limitation (FEV1 x100/forced vital capacity (FVC) being < 65) at follow-up. A random sample of 1,933 men aged 22-54 years in Bergen, Norway, were invited into the survey. Smoking habits and measurements of FEV1 were recorded at the initial survey in 1965-1970 (n = 1,591) and at follow-up in 1988-1990 (n = 951). Past or present self-reported occupational exposures to eleven airborne agents (dusts, gases, vapours and fumes) and measurements of FVC were recorded at follow-up only. The decline in FEV1 was associated (p < 0.001) with age, body height and smoking. Smoking cessation reduced the decline to the level of lifetime nonsmokers. Accelerated decline in FEV1 was observed in subjects exposed to sulphur dioxide gas and to metal fumes. The adjusted decline in FEV1 increased progressively in subjects exposed to increasing numbers of occupational agents (test for trend: p < 0.01). Airflow limitation was observed in 9.5% at follow-up, and increased with age and cigarette consumption. In this community follow-up survey in men, smoking and occupational exposures to sulphur dioxide gas, metal fumes and the numbers of specific agents were found to be important predictors for accelerated decline in FEV1.

Abstract  Much concern has been raised over the health consequences of workers exposed to carbon nanotubes. In order to characterize multi-wall carbon nanotubes (MWCNT) suspended in a phosphate-buffered saline containing 0.1% Tween 80 for an intratracheal instillation study. Length and width distributions of the MWCNT fibers, dispersion of MWCNT in the suspension and in the lung tissue and the MWCNT contents of metal impurities were investigated. Arithmetic mean length and width of the MWCNT fibers as measured on scanning electron microscope (SEM) photographs were 5.0 microm and 88 nm, respectively, and fibers longer than 5.0 microm were 38.9% of all fibers measured. Dynamic light scattering size measurement revealed that 5-min ultrasonication, together with addition of Tween 80 into the suspension, decreased the hydrodynamic diameters of the agglomerated MWCNT to those of finer particles below 1.0 microm. SEM observation showed good dispersion of MWCNT in the suspension, and in the alveoli on Day 1 after instillation. Concentration of iron, chromium and nickel in the MWCNT were 4,400, 48 and 17 ppm (wt/wt), respectively, all of which were below levels that would elicit positive pulmonary toxic responses to these metals. The results suggest that well-dispersed, long and thin MWCNT fibers exhibit asbestos-like pathogenicity in the lung.

Abstract  During the recent decades, rapid urbanization growth has led to even faster growth of motor vehicles and especially in large cities. Hence, evaluation of the actual level of traffic emissions has gained more interest. This paper, for the first time, presents a bottom-up approach for evaluation of vehicular emissions in Tehran- the capital of Iran- using the International Vehicle Emission (WE) model. The IVE model uses local vehicle technology levels and its distributions, power based driving factors, vehicle soak distributions and meteorological parameters to tailor the model for specific evaluation of emissions. The results of this study demonstrate that carbon monoxide (CO) emission with 244.45 ton/hr during peak traffic hour is the most abundant criteria pollutant. About 25% of this quantity is emitted during start-up periods. Other pollutants such as NOx, VOCs, PM, VOCevap and SOx are ranked after CO accordingly. Also, carbon dioxide (CO2) emissions of 1744.22 ton/hr during the study period indicate that light vehicles are responsible for more than 82% of this amount. Based on IVE's evaluation, about 25% of the total vehicle emissions in Tehran come from districts 2, 4 and 6 respectively. It has further been inferred that the development of public transportation systems and proper land-use and urban spatial planning for various centers in these districts are essential.

Abstract  The asbestiform mineral balangeroite [(Mg,Fe2+,Fe3+,Mn2+)42Si16O54(OH)36], whose toxic potential is unknown, is associated with chrysotile asbestos in the western Alps (Balangero mine, Piedmont, Italy). In order to examine whether such fibers may contribute to the oxidative damage produced by local asbestos dusts when inhaled, balangeroite was studied by means of both cell-free and cellular tests, comparing the results with those concerning the most pathogenic asbestos form, crocidolite. Similarly to the crocidolite surface, iron was mobilized from balangeroite by chelators, to a different extent: deferoxamine > ascorbic acid > ferrozine. Poorly coordinated surface ions, as evaluated from the adsorption of NO as a probe molecule (by both calorimetry and infrared spectroscopy), are even more abundant on balangeroite than on crocidolite. The spin trapping technique shows that surface iron-derived Fenton activity (HO* from H2O2) is similar for the two fiber types, while a pretreatment in ascorbic acid, by reducing previously oxidized surface iron, activates the potential to cleave a C-H bond (yielding *CO2- from formate anion). Balangeroite, like crocidolite, produces nitrite accumulation, lipid peroxidation, and NO synthase activation in a human lung epithelial cell line (A549). All these findings, regarded as features related to the toxic potential of asbestos, suggest that balangeroite may be a potentially hazardous fiber per se and could be partly responsible for lung diseases reported in epidemiological studies in exposed miners.

Abstract  The purpose of the study was to compare the cytotoxicity of man-made vitreous fibres (MMVFs): four refractory ceramic fibres (RCFs 1-4), two glasswool fibres (MMVF 10 and 11), a rockwool fibre (MMVF 21) and a slagwool fibre (MMVF 22). The ability of the fibres to induce haemolysis in sheep erythrocytes, to release lactate dehydrogenase (LDH) from rat alveolar macrophages (AM) and to increase the production of reactive oxygen metabolites (ROMs) in human polymorphonuclear leukocytes (PML) was studied. To assess the relative cytotoxicity of MMVFs, their toxicity was compared with that induced by quartz, chrysotile or titanium dioxide. MMVFs induced a modest, but dose-dependent, increase of haemolysis at doses of 0.5, 2.5 and 5.0 mg ml-1. The amount of haemolysis and LDH release induced by MMVFs was generally similar to that induced by titanium dioxide. Glasswool fibre MMVF 10 induced less LDH release from rat AM than rockwool MMVF 21 or slagwool MMVF 22 fibres, whereas glasswool fibre MMVF 11 induced less LDH release than slagwool fibre MMVF 22 (P < 0.05). All fibres also dose-dependently increased the production of ROMs at doses between 25 and 500 micrograms ml-1. The shapes of the time-courses of MMVF-induced production of ROMs suggest that the mechanisms whereby the different fibres induce ROM production may exhibit similar features. There are clear-cut differences in the potency of various MMVFs to induce cytotoxicity and oxidative burst. The present results also emphasize the importance of using several measures of toxicity when assessing the biological activity of various fibres in vitro.

Abstract  The Nevoria deposit (production 11.88 t Au, 0.41 t Ag) is one of more than 20 gold skarns mined in the 3.1 to 3.0 Ga Southern Cross greenstone belt. The belt constitutes part of the continental foreland of the 2.7 to 2.6 Ga Norseman-Wiluna fold belt, the youngest Archean orogen of the Yilgarn craton. The Nevoria skarns are confined to iron formations at the limb of a regional F, anticline bent around the Ghooli orthogneiss dome. The refolding (F-2) took place at 2775 to 2724 Ma during batholith emplacement and contact metamorphism at estimated P-T conditions of 610degrees +/- 50degreesC and 400 +/- 100 MPa (14-km burial depth). This structural setting differs from that of the mezozonal lode gold deposits in the adjacent fold belt, which are controlled by fault-vein arrays in crustal-scale shear zones. The Nevoria orebodies (6-7 g/t Au), composed of pyrrhotite-rich hedenbergite-actinolite and almandine-hornblende skarns, are dated by a concordant U-Pb age (2635.7 +/- 1.2 Ma) and by a less precise Pb-Pb errorchron age (2630 +/- 13 Ma, MSWD = 5.9, n = 7), both defined by allanite-bearing almandine and by cogenetic scheelite. These ages demonstrate that the skarns formed 90 m.y. after amphibolite-facies metamorphism in the Southern Cross greenstone belt and at least 20 m.y. after transpressional faulting related to late-orogenic deformation in the Norseman-Wiluna fold belt. The peak fluid temperature during skarn formation is estimated at 550degrees to 600degreesC, based on the Fe-Mg exchange thermometry of almandine-biotite and almandine-hornblende pairs. Calcic-potassic mineral assemblages in skarn hosted by amphibolite constrain the pressure to 300 to 400 MPa, based on the reaction of biotite + cummingtonite + anorthite to almandine + grossular + biotite. The pressure estimate confirms that the Nevoria deposit formed at considerable depth (11-14 km) in a midcrustal environment. Substantial uplift did not take place until 2565 25 Ma, when biotite in the associated granite closed to Rb-Sr diffusion at 300degreesC ambient temperature. The Nevoria orebodies are cut by pegmatite dikes and are underlain by a 500-m-thick pluton of peraluminous two-mica granite. The concordant zircon U-Pb age (2634 4 Ma) of the granite is indistinguishable from the age of the skarn. The abundance of pegmatite in the main intrusion, increasing upward to a more than 80-m-thick roof zone, indicates that an aqueous fluid separated from the melt. The enrichment of aluminum, Au, As, Bi, Cu, Nb, W, and Zn in the upper pegmatite suggests that these elements were transported to the roof by an early magmatic fluid (700degrees-600degreesC), prior to the development of disseminated muscovite-epidote-carbonate alteration at a lower temperature (400degreesC). The major and trace elements elevated in the pegmatite are also enriched in the ore skarn, implicating the granite as the fluid source. Fluid inclusion data indicate that the magmatic fluid was CO2 bearing, aqueous, and of moderate salinity (about 10 wt % CaCl2 + NaCl equiv). Gold skarn formed in the iron formations above when the infiltrating fluid became progressively reduced during the replacement of grunerite. Other gold skarn deposits in the continental foreland of the Norseman-Wiluna fold belt show a similar space-time relationship to differentiated I-type granites (Thornton-Tuttle index >90). These granites (2.66-2.62 Ga) postdate the compressional deformation in the fold belt and are thus classified as postorogenic. The scheelite-bearing Archean gold skarns share characteristic features such as gangue-sulfide mineralogy and granite association with the deep-seated (150-250 MPa), reduced tungsten skarns located on the continental side of the North American Cordillera. Cretaceous deposits such as MacTung contain up to 2 g/t gold, locally.

Abstract  In two serpentinite mines and in a factory producing asphalt pavements using serpentinite, exposure to dusts and polycyclic aromatic hydrocarbons (WWA-fraction soluble in benzene) was assessed. In rock samples taken in the serpentinite mine and in dust samples from work posts crystalline phases were determined (using X-ray radiography and spectrometry in infrared). Also, morphology of dust particles was performed using electron microscopy. Both in the rock samples and in dust fibrous antigorite, a mineral of strong cancerogenic properties, was found. Total dust concentrations varied between 1.05 and 280 mg/m3, concentration of respirable mineral fibres from 0.01 to 3.56 fibre/cm3, and concentration of aromatic hydrocarbons varied between 266.7 and 850 micrograms/m3. The study will be continued concerning evaluation of biological effect of serpentinite in animal experiments and assessment of extraoccupational exposure of people living in the neighbourhood of serpentinite mines and plants processing this mineral.

Abstract  To investigate lung cancer risk, the authors conducted a historical cohort mortality study of 4,459 mild steel welders who had been employed at three midwestern plants which manufactured heavy equipment. Follow-up began in the mid-1950s and extended through 1988. All welders had at least 2 years welding experience (average duration, 8.5 years). This cohort had no occupational exposure to asbestos or stainless steel fumes (containing nickel and chromium), two potential confounders in previous welders studies. A comparison population of 4,286 nonwelders, all with at least 2 years employment at the same plants, was also studied. Nonwelders had never been welders and were allowed to have no more than 90 days employment as a painter, foundryman, or machinist. Sampling data collected from 1974–1987 indicated that welders were exposed to 6–7 mg/m3 of total particulate and 3–4 mg/m3 of iron oxide, while nonwelders had negligible exposures to welding fumes. When compared with the United States population, both welders and nonwelders had elevated rates for lung cancer (standardized mortality ratios (SMR5): welders, SMR = 1.07; nonwelders, SMR = 1.17), but neither SMR was significantly elevated. Limited smoking data based on a 1985 survey indicated that both welders and nonwelders smoked more than the United States population, possibly accounting for part of their elevated lung cancer rates. There was no trend of increased risk for welders with increased duration of exposure. The only other cause of death significantly elevated was emphysema among welders. Nonmalignant respiratory disease was not elevated for welders (SMR = 0.96). When welders were compared with nonwelders directly for lung cancer, the rate ratio was 0.90.

Abstract  Titanium dioxide (TiO2) nanoparticles (NPs) are the important nanoscale components of composites. Although TiO2 NPs and their related nanocomposites have been widely used in industrial and medical applications, the adverse effects of TiO2 nanomaterials have not been well studied. Here, we investigated the cytotoxicity of TiO2 NPs in vitro using four liver cell lines: human hepatocellular carcinoma cell line (SMMC-7721), human liver cell line (HL-7702), rat hepatocarcinoma cell line (CBRH-7919) and rat liver cell line (BRL-3A). We checked cell viability, cell morphology, and the levels of reactive oxygen species (ROS) and glutathione (GSH) after TiO2 exposure at varying concentrations (01-100 mu g/mL) and different exposure periods of time (12-48 h). Compared to the NP-free control, all four cell lines exposed to TiO2 NPs showed cytotoxicity in a dosage-dependent and time-dependent manner, which was associated with the changes of cell viability and cell morphology, increased intercellular ROS levels, and decreased intracellular GSH levels. Further, we observed that carcinomatous liver cells and human liver cells exhibited more tolerance to TiO2 NPs exposure for 24 h, compared to normal liver cells and rat liver cells, respectively. The results indicate that the in vitro cytotoxicity induced by NPs should be assessed with great caution before the use of nanocomposites and that there is a need to standardize the cytotoxicity testing procedure of nanoscale components in composites when using different cell lines. (C) 2011 Elsevier Ltd. All rights reserved.

Abstract  Objective-To assess the risk of cancer from inhalation of mineral acid mists. Methods-A cohort study and nested case-control study of upper aerodigestive tumours were carried out in men employed since 1950 at two battery plants and two steel works in Britain. The cohort was identified from personnel records and included 2678 men with definite exposure to acid mists (mainly sulphuric acid), 367 with possible exposure, and 1356 who were unexposed. Mortality was compared with that in the national population by the person-years method. Cases of upper aerodigestive cancer were identified from death certificates and cancer registrations, and their exposure to acids was compared with that of age matched controls (five per case) from the same plant by conditional logistic regression. Results-In follow up to 31 December 1993, 93% of men were traced, including 1277 who had died. Among the men definitely exposed to acid mists, overall mortality was less than in the national population (standardised mortality ratio (SMR) 0.92, 95% confidence interval (95% CI) 0.85-0.98) as was mortality from all cancers (SMR 0.92, 95% CI 0.79-1.05) and specifically from cancer of the larynx (SMR 0.48, 95% CI 0.01-2.70) and lung (SMR 0.98, 95% CI 0.78-1.22). A total of 15 incident or fatal cases of upper aerodigestive cancer were identified during follow up. When these men were compared with controls, risk was moderately increased in those who had worked for at least five years in jobs entailing exposures to sulphuric or hydrochloric acid in excess of 1 mg/m(3) (OR 2.0, 95% CI 0.4-10). Conclusions-These findings are consistent with those from other studies which have indicated a hazard of upper aerodigestive cancer from acid mists. However, they indicate that any risk from exposures to sulphuric and hydrochloric acid below 1 mg/m(3) is small.

Abstract  BACKGROUND: The Avon Longitudinal Study of Pregnancy and Childhood is a prospective study of women who were resident in Avon and who were expected to deliver a baby between April 1991 and December 1992.

METHODS: The study provided an opportunity to test the repeatability of responses from 220 women who experienced a miscarriage and who reported exposure to occupational substances and common household products and appliances in two questionnaires. The first questionnaire was completed in the early part of the pregnancy and the second after the miscarriage. Women were asked to score their frequency of exposure on a five-point scale from 'daily' to 'never'. Their responses were analysed to assess the degree of agreement between replies to identical questions in the two questionnaires using the kappa statistic. A new frequency variable was created which compared the replies for the two questionnaires; this was analysed for all exposures by cross-tabulation with possible explanatory variables (age of mother, social class, history of miscarriage and the time lag between questionnaires).

RESULTS: In general there was good agreement in the reported exposures to 48 substances and products. The results showed a small and consistent pattern of reporting exposures less frequently in the second questionnaire, i.e. after miscarriage. This was not explained by the analysis of possible confounding variables. Given the literature, the authors had expected to find a shift in the opposite direction.

CONCLUSION: The study reinforces the need to be cautious when using the results from single surveys of retrospective self-reported exposure.

Abstract  Residential radon has been shown to be a risk factor for lung cancer in several studies-but with limited power in each single study. The data of two case-control studies performed during 1990-1997 in Germany and used for previous publications have been extended and pooled. Both studies have identical study designs. In total, data of 2,963 incident lung cancer cases and 4,232 population controls are analyzed here. One-year radon measurements were performed in houses occupied during the 5-35 y prior to the interview. Conditional logistic and linear relative risk regression was used for the analysis. Measurements covered on average 70% of the exposure time window, with an average radon exposure of 61 Bq m(-3). The smoking and asbestos-adjusted ORs were 0.97 [95% confidence interval (CI) 0.85 to 1.11] for 50-80 Bq m(-3), 1.06 (95% CI 0.87 to 1.30) for 80-140 Bq m(-3) and 1.40 (95% CI 1.03 to 1.89) for radon concentrations above 140 Bq m(-3), compared to the reference category <50 Bq m(-3). The linear increase in the odds ratio per 100 Bq m(-3) was 0.10 (95% CI -0.02 to 0.30) for all subjects and 0.14 (95% CI -0.03 to 0.55) for less mobile subjects who lived in only one home in the last 5-35 y. The risk coefficients generally were higher when measurement error in the radon concentrations was reduced by restricting the population. With respect to histopathology, the risk for small cell carcinoma was higher than for other subtypes. This analysis strengthens the evidence that residential radon is a relevant risk factor for lung cancer.

Abstract  Titanate fibres and whiskers are new materials with high heat resistance and good chemical stability. They have found numerous applications such as ion exchanger materials, thermal insulators, reinforcements, catalysts, photocatalysts and substitutes of asbestos. In this paper, the methods of fabricating potassium titanate fibres and whiskers have been discussed, e. g., calcination, hydrothermal reaction, flux growth, sol-gel technique, and others. Because asbestos fibres are known to cause fibrotic diseases in lungs we also refer to studies into the toxicity and carcinogenicity of potassium titanate fibres and whiskers.