Abstract  In the area of the Taro-Ceno Valleys (Northern Apennine, Emilia-Romagna region, Italy), waters of meteoric origin interact with ophiolite rocks of the External Ligurides. Fresh water springs issuing from basalts have a Ca-HCO3 composition, whereas freshwater springs from ultramafites vary in composition from Ca-HCO3 or Mg-HCO3 to Na-OH OF Na-SO4 types and in pH values from 7.3-8.8 LIP to pH 11, respectively. In addition, the boron content of the alkaline waters is LIP to 13 mg/L, which is unusually high for freshwaters in general and ultramafites that have undergone oceanic serpentinisation in particular and gives a boric alkalinity to the waters. The springs waters show evidence of recent low-temperature continental serpentinisation and the process is modeled by reaction paths using an updated geochemical thermodynamic database, consistent with the local primary and secondary serpentinite paragenesis. For the model, bicarbonate waters evolve to alkaline waters supersaturated in Ca-(Mg)-carbonate, based on the assumption that the dissolution of serpentinite results in supersaturation with respect to kaolinite, ferrihydrite, vermiculite, Fe2+-Mg2+-saponite, and poorly crystalline serpentine. The alkaline composition and the chloride content of the waters suggest a prolonged interaction with the rocks at depth that led to dissolution of albite and leaching of olivine-hosted fluid inclusions. A similar evolution is also proposed for the more developed springs issuing from the ultramafic rocks of the Voltri Group (Liguria region), where solutions are supersaturated in brucite and are in equilibrium with enstatite and/or chlorite. (C) 2008 Elsevier B.V. All rights reserved.

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  Asbestos-containing brake linings were used in heavy-duty construction equipment such as tractors, backhoes, and bulldozers prior to the 1980s. While several published studies have evaluated exposures to mechanics during brake repair work, most have focused on automobiles and light trucks, not on heavy agricultural or construction vehicles. The purpose of this study is to characterize the airborne concentration of asbestos to workers and bystanders from brake wear debris during brake removal from 12 loader/backhoes and tractors manufactured between 1960 and 1980. Asbestos content in brake lining (average 20% chrysotile by polarized light microscopy) and brake wear debris [average 0.49% chrysotile by transmission electron microscopy (TEM)] was also quantified. Breathing zone samples on the lapel of mechanics (n = 44) and area samples at bystander (n = 34), remote (n = 22), and ambient (n = 12) locations were collected during 12 brake changes and analyzed using phase contrast microscopy (PCM) [National Institute for Occupational Safety and Health (NIOSH) 7400] and TEM (NIOSH 7402). In addition, the fiber distribution by size and morphology was evaluated according to the International Organization for Standardization method for asbestos. Applying the ratio of asbestos fibers:total fibers (including non-asbestos) as determined by TEM to the PCM results, the average airborne chrysotile concentrations (PCM equivalent) were 0.024 f/cc for the mechanic and 0.009 f/cc for persons standing 1.2-3.1 m from the activity during the period of exposure ( approximately 0.5 to 1 h). Considering the time involved in the activity, and assuming three brake jobs per shift, these results would convert to an average 8-h time-weighted average of 0.009 f/cc for a mechanic and 0.006 f/cc for a bystander. The results indicate that (i) the airborne concentrations for worker and bystander samples were significantly less than the current occupational exposure limit of 0.1 f/cc; (ii) approximately 2% of respirable fibers were >20 microm in length; and (iii) approximately 95% of chrysotile in the brake linings degraded in the friction process. The industrial hygiene data presented here should be useful for conducting retrospective and current exposure assessments of individuals, as well as hazard assessments of work activities that involve repairing and replacing asbestos-containing brakes in heavy construction equipment.

Abstract  OBJECTIVE: To investigate whether asbestosis is a risk factor for mortality of lung cancer.

METHODS: A fixed cohort study was established in an asbestos plant in Chongqing, China, and followed up for 30 years from the beginning of 1972. Basic personal information on life state, cause of death, and diagnosis of asbestosis was collected. Multiple logistic regressions were applied to analyze risk factors.

RESULTS: During the 30-year follow-up, 584 male workers constituting a total of 14,664 person-years were monitored and data were analyzed. Among them, 203 (34.8%) died and the mortality rate was 13.8 per 1000 person-years, cancer accounting for 37.4%. Excess risks were observed for lung cancer (OR = 3.72) and nonmalignant respiratory diseases (OR = 2.73) among workers with asbestosis. High-exposure level was another risk factor for lung cancer (OR = 3.20). Workers with category II of asbestosis demonstrated a higher OR of both lung cancer and nonmalignant respiratory diseases than those with category I of asbestosis.

CONCLUSION: High asbestos exposure level and asbestosis were the risk factors for death of lung cancer and nonmalignant respiratory diseases. Asbestosis is an independent risk factor for lung cancer among Chinese workers exposed to chrysotile, the risk increases with the increasing profusion of opacities of lung.

Abstract  The rationale behind and operation of the Workplace Analysis Scheme for Proficiency (WASP) were described. WASP was designed as an external quality assurance check for laboratories conducting chemical analysis of air samples collected in the workplace. The types of samples offered in the initial rounds of WASP included samples of lead (7439921), cadmium (7440439), chromium (7440473), benzene (71432), toluene (108883), m-xylene (1330207), 1,1,1-trichloroethane (71556), trichloroethene (79016), and tetrachloroethane (79345) loaded onto glass fiber, membrane filter, charcoal, or Tenax mediums. The analyte loading ranges of each sample reflected levels that would normally be collected by sampling work atmospheres between 0.2 and 2.0 times the relevant occupational exposure limit. The participating laboratories received four samples of each type selected and were allowed one month to return the results. Conclusions from the WASP surveys conducted to date indicated that there are significant differences in performance between laboratories, and many analyses are not of an acceptable standard.

Abstract  Objectives: Pulmonary parenchymal changes appear many years after the start of exposure to asbestos and their progression has been observed to continue many years after cessation of the exposure. The aim of the present analysis is to assess the risk of progression of radiological changes in the respiratory system, based on long-term follow-up of groups of workers occupationally exposed to asbestos dust. Materials and methods: The analysis included 3144 individuals voluntarily applying for a medical examination in 2000-2010, who had performed at least two radiographs of the chest. Probability of progression in subsequent studies was based on the evaluation of radiographs for the presence of small, irregular type s, t, u opacities in the parenchymal lung tissue with profusion categories as specified in the classification of ILO, 1980. Multistate hidden Markov model was used in the statistical analysis. Results: In the group of patients, small irregular opacities with a profusion of 1/1 or higher occurred in 640 (20%) patients in the first examination, and in 918 (29%) patients in the last examination. No parenchymal changes were observed in 1360 (43%) patients in the first examination (opacity profusion category 0/0), and in 645 (20%) patients in the last examination. The risk of progression of radiographic changes in former workers of asbestos processing plants is higher in smokers, from profusion category 0 to 1 - by 30% (HR = 1.30, 95% CI: 1.15-1.47), from profusion category 1 to 2 - by 50% (HR = 1.50, 95% CI: 0.92-2.45). The risk of progression of parenchymal changes decreases in the workers employed in subsequent calendar years: for category changes from 1 to 2, the decrease is nearly 40% for every 10 years of subsequent employment (HR = 0.60, 95% CI: 0.45-0.80). The probability of the progression increases with longer latency period: for change of category from 1 to 2, the increase is about 20% (HR = 1.19, 95% CI: 1.00-1.42) per 10 years of employment for blue collar workers. The risk of the 1 to 2 category progression is significant, nearly 2.5-fold higher in the workers employed in the asbestos-processing textile industry. Conclusions: Our results show that the risk of progression of pulmonary parenchymal fibrotic processes was higher in the smokers, workers employed during the earlier calendar years of the discussed period, those with longer latency period, blue collar workers involved directly in the production processes, and employees of the asbestos cement and/or textile industries.

Abstract  ABSTRACTS BACKGROUND: Multi-walled carbon nanotubes (MWCNT)s are suspected to induce pulmonary and pleural cancers due to their asbestos-like configurations. Therefore, accurate measurement of inhaled nanotubes in target organs is crucial for assessing cancer risk. Conventionally, nanotubes are measured after combustion at high temperature for conversion into CO2; however, the sensitivity is poor and the method lacks versatility. We have therefore developed a novel approach using hybrid markers for nanotube analysis, featuring high sensitivity and the capacity to conduct repeated analyses. The method involves adsorption of markers to nanotubes, followed by their desorption and assessment by means of high performance liquid chromatography (HPLC).

METHODS: Recovery of MWCNT from rat lungs was conducted, and pulmonary MWCNT amounts were determined using rats intratracheally-exposed to MWCNT aerosol at 5 mg/m3 for 6 hours/day.

RESULTS: The correlation coefficient for the calibration curve of MWCNT weight and the HPLC area was 0.9991. Consequently, the lower quantitation limit yielded was 0.2 μg. The recovery was 92-98% at approximately 0.4-2.0 μg demonstrating that MWCNTs in the lung could be measured accurately and precisely.

CONCLUSIONS: We have developed a novel method using a hybrid marker approach for nanotube analysis, featuring very high sensitivity and the capacity to conduct repeated analyses. We further confirmed correlations between the amounts of nanotubes and markers and pulmonary nanotube measurement demonstrated that trace amounts could be detected with values closely relating to the administered dose, verifying that the method is sensitive and precise.

Abstract  INTRODUCTION: Brake linings and brake pads are among the asbestos-containing products that are readily available in Colombia. When sold separated from their support, brake linings require extensive manipulation involving several steps that include drilling, countersinking, riveting, bonding, cutting, beveling, and grinding. Without this manipulation, brake linings cannot be installed in a vehicle. The manipulation process may release asbestos fibers, which may expose brake mechanics to the fibers.

METHODS: Three brake repair shops located in Bogotá (Colombia) were sampled for 3 or 4 consecutive days using US National Institute for Occupational Safety and Health (NIOSH) methods 7400 and 7402. Standard procedures for quality control were followed during the sampling process, and asbestos samples were analyzed by an American Industrial Hygiene Association accredited laboratory. Personal samples were collected to assess full-shift and short-term exposures. Area samples were also collected close to the brake-lining manipulation equipment and within office facilities. Activities were documented during the sampling process.

RESULTS: Using Phase Contrast Microscopy Equivalent counts to estimate air asbestos concentrations, all personal samples [i.e. 8-h time-weighted averages (TWAs) and 30-min personal samples] were in compliance with the US Occupational Safety and Health Administration standards. Personal asbestos concentrations based on transmission electron microscopy counts were extremely high, ranging from 0.006 to 3.493 f cm(-3) for 8-h TWA and from 0.015 to 8.835 f cm(-3) for 30-min samples. All asbestos fibers detected were chrysotile. Cleaning facilities and grinding linings resulted in the highest asbestos exposures based on transmission electron microscopy counts. There were also some samples that did not comply with the NIOSH's recommended exposure limits.

CONCLUSION: The results indicate that the brake mechanics sampled are exposed to extremely high asbestos concentrations (i.e. based on transmission electron microscopy counts), suggesting that this occupational group could be at excess risk of asbestos-related diseases.

Abstract  Background: The objective of this work was to investigate the association between occupational exposure and lung cancer risk based on a case-control study. Material and Methods: The study of 414 primary lung cancer cases, recorded in the Lodz industrial center in the years 1998-2002, was carried out under the international multicentre case-control study, coordinated by the International Agency for Research on Cancer (IARC). The control group, composed of individuals who did not report any tobacco-related diseases or other cancers, were matched by gender and age. Data on lung cancer risk factors were derived from a questionnaire survey on life styles and occupational exposure. The detailed information on the occupational history of all the study subjects and exposure to lung carcinogens was collected and subsequently assessed by occupational hygienists. Logistic regression was used in the data analysis. Confounders, such as age, gender, education, diet and cigarette smoking were controlled in the analysis. Results: A total of 88 case patients and 79 controls had been employed in occupations and industries associated with the evidenced or suspected risk of lung cancer development. The corresponding odds ratio was 0.71 (95%CI: 0.48-1.06). The study population was mostly exposed to organic dust, lubricating oil mist, sand, mild steel dust, organic solvents and abrasives dust. Conclusions: The present study provides evidence that occupational exposure in the investigated Lodz industrial center is responsible for a moderate increase in lung cancer risk among exposed persons. However, only a small fraction of the study population was exposed to well documented carcinogens.

Abstract  BACKGROUND: Drywall joint compound contained asbestos fibers, primarily chrysotile, in the 1950s through the 1970s. Workers in a variety of construction trades and homeowners were exposed to respirable asbestos from the use of these products, including during handling, mixing, sanding, and sweeping. Disturbance of in-place asbesto-containing joint compound continues to be a potential source of exposure during demolition or repair of wallboard. Studies from the 1970s and 1980s report air fiber measurements above current and historic regulatory limits during intended usage, and typical asbestos-related disease in drywall construction workers.

OBJECTIVES: We present three cases of mesothelioma in which the only known exposure to asbestos was from joint compound and review the literature on exposure circumstances, dose and fiber types.

CONCLUSIONS: Physicians treating mesothelioma patients should obtain a history of exposure to these products during work or home remodeling.

Abstract  BACKGROUND: The question of whether chrysotile asbestos-containing brake dust can plausibly serve as a cause of mesothelioma in an exposed individual has become a matter of heated debate in the medical literature despite multiple international, federal, and state governmental agencies acknowledging a causal association.

OBJECTIVES: We describe and provide an analysis of various industry and academic perspectives contributing to the debate.

METHODS: A framework is presented for evaluating the general and specific causal relationship between brake dust exposure and mesothelioma utilizing the principles of forensic epidemiology, and by applying the Bradford-Hill criteria.

RESULTS AND CONCLUSIONS: We conclude that there is a "net" of evidence favoring a causal relationship between brake dust-associated chrysotile exposure and mesothelioma. The industry-sponsored position that there is insufficient evidence to support a contiguous "chain" of causation is specious from both a methodologic and evidentiary perspective. Finally, we suggest a semiquantitative approach for the evaluation of individual causation in putative cases of mesothelioma with a history of significant brake dust exposure.

Abstract  Serpentinized oceanic lithosphere may be an important source for boron and other fluid-mobile elements that are anomalously enriched in are volcanic rocks. However, the integrated water/rock ratios associated with different styles of serpentinization may be variable. For example, large water/rock ratios are involved in the serpentinization of abyssal peridotites exhumed to the seafloor, whereas much lower water/rock ratios are likely to dictate serpentinization along deep faults and fractures. To address how fluidmobile element enrichments vary with serpentinization at different settings, we investigated serpentinized harzburgites from the Feather River Ophiolite (FRO) in northern California. Major and trace element systematics indicate that serpentinization of the FRO ultramafics involved seawater. However, FRO serpentinites have unradiogenic Os isotopic compositions and near-chondritic platinum group element relative abundances, contrasting with serpentinized abyssal peridotites, which have radiogenic Os isotopic compositions and disturbed platinum group element systematics. These observations indicate that the integrated water/rock ratio involved in FRO serpentinization was smaller than that involved in abyssal peridotite serpentinization. B concentrations in the FRO (5-15 ppm), while substantially higher than primitive mantle (< 0.1ppm), are still lower than in abyssal peridotites (10- 170 ppm). These low values are not due to metamorphic loss as there is no petrographic evidence for prograde metamorphism (the serpentine minerals are low temperature forms like chrysotile and lizardite) and there is no consistency between observed fluid-mobile element (B, As, Ph, and Li) contents and depletions predicted from metamorphic dehydration models. Low B and fluid-mobile element contents in the FRO may thus be an intrinsic feature of low water/rock ratio serpentinization. Such values may be more representative of serpentinized oceanic lithospheric mantle rather than abyssal peridotites, which sample only the top veneer of the lithosphere. (c) 2007 Elsevier B.V. All rights reserved.

Abstract  To investigate factors related to lung cancer mortality in six Arizona copper smelter towns, we identified 185 lung cancer cases and two matched controls per case from decedent residents during 1979-1990. Detailed information on lifetime residential, occupational, and smoking history was obtained by structured telephone interviews with knowledgeable informants. Interviews were completed for 82% of 183 eligible cases and 88% of the targeted number (366) of controls. Estimated historical environmental exposures to smelter emissions, based on atmospheric diffusion modeling of measured SO2 concentrations, were linked with residential histories to derive individual profiles of residential exposure. Occupational histories were characterized by potential exposure to smelter emissions, asbestos, and ionizing radiation. Conditional logistic regression was used to compare study factors in cases and controls with adjustment for potential confounding factors: gender, Hispanic ethnicity, and smoking. In overall and gender-specific analyses, no statistically significant associations were observed between lung cancer risk and any of the measures of residential exposure to smelter emissions considered (town of residence at time of death, highest level of exposure, and duration or cumulative exposure above background levels), or any of the estimated occupational exposures (definite or potential asbestos, potential ionizing radiation, definite or potential smelter). Among male residents of some, but not all, towns, there was some evidence of a positive association between lung cancer risk and reported copper smelter-related employment (reported as definite), with the highest risk observed for Miami, Arizona. This study provided little evidence of a positive association between lung cancer mortality and residential exposure to smelter emissions. Specific factors associated with the apparent heterogeneity in lung cancer risk across study towns cannot be identified in this community-based study.

Abstract  Numerous sources of asbestos exist that may contribute to non-occupational exposures, among the important ones being building surfacing materials that have been damaged or allowed to deteriorate. Even more important is the potential exposure from improperly controlled maintenance activities in buildings. Evidence exists suggesting that vehicle braking makes a significant contribution to ambient asbestos levels, but more data are required to establish its extent. Many asbestos materials are present in homes, and fibres may be released during home renovations or repairs. Little information exists on the levels of other mineral fibres in the non-occupational environment or on the relative contributions from potential sources.

Abstract  This study reports on personal airborne lead exposure levels of workers removing windows painted with lead-based paint (LBP) and having asbestos caulking. Abatement/Removal of windows with LBP and asbestos caulking is becoming a common practice in the United States by environmental firms. As a result of both asbestos and lead regulations, many state regulatory agencies are categorizing this type of work as abatement and specification requirements are being issued for such work. However, little information has been published on exposure levels to asbestos and lead during various work practices. Exposure results presented in this study provide some historical (objective) data for abatement of windows with asbestos-containing materials (ACM) and LBP.

Abstract  Certain measurement techniques (such as the asbestos method using phase contrast microscopy) require uniform deposits of the sample on a filter. The asbestos fiber analytical methods require such uniform deposition because the analysis only observes small, randomly chosen locations on the filter. In this study, a vibrating orifice monodisperse aerosol generator was used to generate methylene blue particles. The aerosols were dried by filtered compressed air and then neutralized by inducing a charge on the droplet stream that emerged from the vibrating orifice. An Aerodynamic Particle Sizer was used to measure the number concentration and size distribution of the generated aerosol particles. Meanwhile, the filter deposits were examined via image processing, combined with statistical methods for defining uniformity. In order to better define uniformity and make the indicator more universal, the uniformity was defined as the exponential of the negative CV (coefficient of variation) value which was a transformation for easily understanding the uniformity of the filter deposits. The experimental results demonstrated that, when aerosol counting was performed, the equal area approach was superior to the equivalent distance approach.

Abstract  Prevailing theories suggest that acicular, or fiber-like, particles induce enhanced toxicity over isotropic materials through hindrance of phagocyte-mediated clearance mechanisms and through the aggravation of proximal cells via mechanical interactions. Currently, the degree to which either of these mechanisms operates is not well understood. To gain a more fundamental understanding of acicular particle toxicity, we have synthesized submicron and nanoscale amorphous silica spheres and rods as model materials for shape-driven toxicological experimentation. To accentuate contributions from mechanical damage in vitro, exposure studies were performed in the presence and absence of simulated lung mechanics. To promote and mitigate cell-particle contact-mediated mechanical interactions, the adhesion of the particles to the cell membrane was respectively modified by the physisorption of fibronectin and the chemisorption of polyethylene glycol to the silica particle surface. Lactic acid dehydrogenase (LDH) and interleukin (IL)-8 release were used as endpoints for cytotoxicity and inflammation, respectively. The results indicate that particle exposures in the presence of physiological stretch induce increased LDH release and IL-8 expression regardless of shape. Moreover, it is evident that shape-induced aggregation may play a significant role in mitigating particle clearance pathways.

Abstract  To determine whether carbon nanotubes can induce any significant health hazards we applied methods routinely used in the pathophysiological testing of asbestos-induced disease to show that the soot with a high content of CNTs does not induce any abnormalities of pulmonary function or measurable inflammation in guinea pigs treated with carbon nanotubes.

Abstract  Major and trace element compositions for chrysotile (2 samples), amosite, crocidolite, and anthophyllite UICC standard asbestos samples have been determined using UV-visible spectrophotometry, atomic absorption spectometry, flame photometry, volumetric analysis, and gravimetric analysis for major elements and x-ray and optical spectrometry for trace elements. The trace element data are for Li, S, Cl, Sc, V, Cr, Co, Ni, Cu, Zn, Ga, Rb, Sr, Zr, Nb, Ba, La, Ce, Pb, and Th and distribution in the various mineral phases is discussed.

Abstract  In a population-based case-referent study, the occupational experience of 86 men with oral or oropharyngeal cancer and 373 referents was analyzed with respect to employment in 41 occupations and 40 industries, as well as to exposure to 16 chemicals, as estimated via a job-exposure matrix. Among the occupations and industries at higher risk were machinery operator (odds ratio [OR] 2.0; 95% confidence interval [95% CI] 1.0-4.0), plumber (OR 5.0, 95% CI 1.2-21.5), building industry (OR 2.5; 95% CI 1.3-4.5), textile industry (OR 2.5; 95% CI 0.6-4.6), and electricity production (OR 2.8; 95% CI 0.7-12.1). All the OR estimates were adjusted for age, education, area of birth, tobacco smoking, and alcohol consumption. An association between formaldehyde exposure and oral cancer was suggested (OR for any exposure 1.6, 95% CI 0.9-2.8; OR for probable or definite exposure 1.8, 95% CI 0.6-5.5). No other chemical included in the matrix showed any risk pattern. The evidence of an association between formaldehyde exposure and oral or oropharyngeal cancer is strengthened by the results of this study.

Abstract  Quantitative estimates of the risk of lung cancer or mesothelioma in humans from asbestos exposure made by the U. S. Environmental Protection Agency (EPA) make use of estimates of potency factors based on phase-contrast microscopy (PCM) and obtained from cohorts exposed to asbestos in different occupational environments. These potency factors exhibit substantial variability. The most likely reasons for this variability appear to be differences among environments in fiber size and mineralogy not accounted for by PCM.

In this article, the U. S. Environmental Protection Agency (EPA) models for asbestos-related lung cancer and mesothelioma are expanded to allow the potency of fibers to depend upon their mineralogical types and sizes. This is accomplished by positing exposure metrics composed of nonoverlapping fiber categories and assigning each category its own unique potency. These category-specific potencies are estimated in a meta-analysis that fits the expanded models to potencies for lung cancer (K(L)'s) or mesothelioma (K(M)'s) based on PCM that were calculated for multiple epidemiological studies in our previous paper (Berman and Crump, 2008). Epidemiological study-specific estimates of exposures to fibers in the different fiber size categories of an exposure metric are estimated using distributions for fiber size based on transmission electron microscopy (TEM) obtained from the literature and matched to the individual epidemiological studies. The fraction of total asbestos exposure in a given environment respectively represented by chrysotile and amphibole asbestos is also estimated from information in the literature for that environment. Adequate information was found to allow K(L)'s from 15 epidemiological studies and K(M)'s from 11 studies to be included in the meta-analysis.

Since the range of exposure metrics that could be considered was severely restricted by limitations in the published TEM fiber size distributions, it was decided to focus attention on four exposure metrics distinguished by fiber width: "all widths," widths > 0.2 mu m, widths < 0.4 mu m, and widths < 0.2 mu m, each of which has historical relevance. Each such metric defined by width was composed of four categories of fibers: chrysotile or amphibole asbestos with lengths between 5 mu m and 10 mu m or longer than 10 mu m. Using these metrics three parameters were estimated for lung cancer and, separately, for mesothelioma: K(LA), the potency of longer (length > 10 mu m) amphibole fibers; rpc, the potency of pure chrysotile (uncontaminated by amphibole) relative to amphibole asbestos; and rps, the potency of shorter fibers (5 mu m < length < 10 mu m) relative to longer fibers.

For mesothelioma, the hypothesis that chrysotile and amphibole asbestos are equally potent (rpc = 1) was strongly rejected by every metric and the hypothesis that (pure) chrysotile is nonpotent for mesothelioma was not rejected by any metric. Best estimates for the relative potency of chrysotile ranged from zero to about 1/200th that of amphibole asbestos (depending on metric). For lung cancer, the hypothesis that chrysotile and amphibole asbestos are equally potent (rpc = 1) was rejected (p <= .05) by the two metrics based on thin fibers (length < 0.4 mu m and < 0.2 mu m) but not by the metrics based on thicker fibers.

The "all widths" and widths < 0.4 mu m metrics provide the best fits to both the lung cancer and mesothelioma data over the other metrics evaluated, although the improvements are only marginal for lung cancer. That these two metrics provide equivalent (for mesothelioma) and nearly equivalent (for lung cancer) fits to the data suggests that the available data sets may not be sufficiently rich (in variation of exposure characteristics) to fully evaluate the effects of fiber width on potency. Compared to the metric with widths > 0.2 mu m with both rps and rpc fixed at 1 (which is nominally equivalent to the traditional PCM metric), the "all widths" and widths < 0.4 mu m metrics provide substantially better fits for both lung cancer and, especially, mesothelioma.

Although the best estimates of the potency of shorter fibers (5 < length < 10 mu m) is zero for the "all widths" and widths < 0.4 mu m metrics (or a small fraction of that of longer fibers for the widths > 0.2 mu m metric for mesothelioma), the hypothesis that these shorter fibers were nonpotent could not be rejected for any of these metrics. Expansion of these metrics to include a category for fibers with lengths < 5 mu m did not find any consistent evidence for any potency of these shortest fibers for either lung cancer or mesothelioma.

Despite the substantial improvements in fit over that provided by the traditional use of PCM, neither the "all widths" nor the widths < 0.4 mu m metrics (or any of the other metrics evaluated) completely resolve the differences in potency factors estimated in different occupational studies. Unresolved in particular is the discrepancy in potency factors for lung cancer from Quebec chrysotile miners and workers at the Charleston, SC, textile mill, which mainly processed chrysotile from Quebec. A leading hypothesis for this discrepancy is limitations in the fiber size distributions available for this analysis. Dement et al. (2007) recently analyzed by TEM archived air samples from the South Carolina plant to determine a detailed distribution of fiber lengths up to lengths of 40 mu m and greater. If similar data become available for Quebec, perhaps these two size distributions can be used to eliminate the discrepancy between these two studies.

Abstract  OBJECTIVES: This community based case-referent study was initiated to investigate aetiological factors for squamous cell carcinoma of the upper gastrointestinal tract. METHODS: The study was based on all Swedish men aged 40-79 living in two regions of Sweden during 1988-90. Within that base, efforts were made to identify all incident cases of squamous cell carcinoma of the oral cavity, oropharynx and hypopharynx, larynx, and oesophagus. Referents were selected as a stratified (age, region) random sample of the base. The response was 90% among cases and 85% among referents. There were 545 cases and 641 referents in the final study group. The study subjects were interviewed about several lifestyle factors and a life history of occupations and work tasks. The exposure to 17 specific agents were coded by an occupational hygienist. The relative risk (RR) of cancer was calculated by logistic regression, standardising for age, geographical region, and alcohol and tobacco consumption. RESULTS: Exposure to asbestos was associated with an increased risk of laryngeal cancer, and a dose-response relation was present. The RR was 1.8 (95% confidence interval (95% CI) 1.1 to 3.0) in the highest exposure group. More than eight years of exposure to welding fumes was associated with an increased risk of pharyngeal cancer (RR 2.3 (1.1 to 4.7)), and laryngeal cancer (RR 2.0 (1.0 to 3.7)). There were indications of a dose-response for duration of exposure. Associations were also found for high exposure to polycyclic aromatic hydrocarbons (PAHs) and oesophageal cancer, RR 1.9 (1.1 to 3.2). Exposure to wood dust was associated with a decreased risk of cancer at the studied sites. CONCLUSIONS: Some of the present findings confirm known or suspected associations--such as asbestos and laryngeal cancer. The study indicates that welding may cause an increased risk of pharyngeal as well as laryngeal cancer. The findings corroborate an association between exposure to PAHs and oesophageal cancer.

Abstract  Objective: In order to examine the associations between sinonasal cancer and occupational exposures other than wood dust and leather dust, the data from 12 case–control studies conducted in seven countries were pooled and reanalyzed. Methods: The pooled data set included 195 adenocarcinoma cases (169 men and 26 women), 432 squamous cell carcinomas (330 men and 102 women), and 3136 controls (2349 men and 787 women). Occupational exposures to formaldehyde, silica dust, textile dust, coal dust, flour dust, asbestos, and man-made vitreous fibers were assessed with a job-exposure matrix. Odds ratios (ORs) were adjusted for age, study, wood dust, and leather dust, or other occupational exposures when relevant. 95% confidence intervals (CIs) were estimated by unconditional logistic regression. Results: A significantly increased risk of adenocarcinoma was associated with exposure to formaldehyde. The ORs for the highest level of exposure were 3.0 (CI = 1.5–5.7) among men and 6.2 (CI = 2.0–19.7) among women. An elevated risk of squamous cell carcinoma was observed among men (OR = 2.5, CI = 0.6–10.1) and women (OR = 3.5, CI = 1.2–10.5) with a high probability of exposure to formaldehyde. Exposure to textile dust was associated with non-significantly elevated risk of adenocarcinoma, among women only: the OR for the high level of cumulative exposure was 2.5 (CI = 0.7–9.0). High level of asbestos exposure was associated with a significantly increased risk of squamous cell carcinoma among men (OR = 1.6, CI = 1.1–2.3). Conclusions: The results of this pooled analysis support the hypothesis that occupational exposure to formaldehyde increases the risk of sinonasal cancer, particularly of adenocarcinoma. They also indicate an elevated risk of adenocarcinoma among women exposed to textile dust, and suggest that exposure to asbestos may increase the risk of squamous cell carcinoma.

Abstract  SW Iberia is interpreted as an accretionary magmatic belt resulting from the collision between the South Portuguese Zone and the autochthonous Iberian terrane in Variscan times (350 to 330 Ma). In the South Portuguese Zone, pull-apart basins were filled with a thick sequence of siliciclastic sediments and bimodal volcanic rocks that host the giant massive sulphides of the Iberian Pyrite Belt. Massive sulphides precipitated in highly efficient geochemical traps where metal-rich but sulphur-depleted fluids of dominant basinal derivation mixed with sulphide-rich modified seawater. Massive sulphides formed either in porous/reactive volcanic rocks by sub-seafloor replacement, or in dark shale by replacement of mud or by exhalation within confined basins with high biogenic activity. Crustal thinning and magma intrusion were responsible for thermal maturation and dehydration of sedimentary rocks, while magmatic fluids probably had a minor influence on the observed geochemical signatures. The Ossa Morena Zone was a coeval calc-alkaline magmatic arc. It was the site for unusual mineralization, particularly magmatic Ni-(Cu) and hydrothermal Fe-oxide-Cu-Au ores (IOCG). Most magmatism and mineralization took place at local extensional zones along first-order strike-slip faults and thrusts. The source of magmas and IOCG and Ni-(Cu) deposits probably lay in a large mafic-ultramafic layered complex intruded along a detachment at the boundary between the upper and lower crust. Here, juvenile melts extensively interacted with low-grade metamorphic rocks, inducing widespread anatexis, magma contamination and further exsolution of hydrothermal fluids. Hypersaline fluids (delta(18)O(fluid) > 5.4 parts per thousand to 12 parts per thousand) were focused upward into thrusts and faults, leading to early magnetite mineralization associated with a high-temperature (>500 degrees C) albite-actinolite-salite alteration and subsequent copper-gold-bearing vein mineralization at somewhat lower temperatures. Assimilation of sediments by magmas led in turn to the formation of immiscible sulphide and silicate melts that accumulated in the footwall of the layered igneous complex. Further injection of both basic and sulphide-rich magmas into the upper crust led to the formation of Ni-(Cu)-rich breccia pipes. Younger (330 to 280 Ma?) peraluminous granitoids probably reflect the slow ascent of relatively dry and viscous magmas formed by contact anatexis. These granitoids have W-(Sn)- and Pb-Zn-related mineralization that also shows geochemical evidence of major mantle-crust interaction. Late epithermal Hg-(Cu-Sb) and Pb-Zn-(Ag) mineralization was driven by convective hydrothermal cells resulting from the high geothermal gradients that were set up in the zone by intrusion of the layered igneous complex. In all cases, most of the sulphur seems to have been derived from leaching of the host sedimentary rocks (delta(34)S =7 parts per thousand to 20 parts per thousand) with only limited mixing with sulphur of magmatic derivation. The metallogenic characteristics of the two terranes are quite different. In the Ossa Morena Zone, juvenile magmatism played a major role as the source of metals, and controlled the styles of mineralization. In the South Portuguese Zone, magmas only acted as heat sources but seem to have had no major influence as sources of metals and fluids, which are dominated by crustal signatures. Most of the magmatic and tectonic features related to the Variscan subduction and collision seem to be masked by those resulting from transpressional deformation and deep mafic intrusion, which led to the development of a metallogenic belt with little resemblance to other accretionary magmatic arcs. (c) 2005 Elsevier B.V. All rights reserved.

Abstract  OBJECTIVE: Our previous study demonstrated the presence of environmental tremolite and chrysotile asbestos fiber exposure in Hekimhan town in Malatya located in eastern Turkey. The aim of this study was to investigate whether environmental asbestos exposure increases the incidence of lung cancer and mesothelioma. METHOD: One hundred and forty-nine patients with mesothelioma and lung cancer living in the center or in the towns of Malatya were retrospectively analyzed. The Incidences of lung cancer and mesothelioma were calculated. RESULTS: The incidences of lung cancer and mesothelioma were 3.39/100,000 and 0.21/100,000, respectively, for the whole population of Malatya; while they were 8.23/100,000 and 1.45/100,000 in Hekimhan. The incidences were strikingly high (22.39/100,000 for lung cancer and 7.46/100,000 for mesothelioma) in Arguvan, another town in Malatya where an analysis for asbestos could not be performed. The overall incidence in Turkey was reported as 5.9/100,000 by the Health Ministry in 1994. The incidences of lung cancer were nearly 1.3-fold higher in Hekimhan and fourfold higher in Arguvan then in the general population of Turkey. CONCLUSION: The incidences of mesothelioma and lung carcinoma in Hekimhan were higher than those of the general population in Turkey, suggesting a role of environmental asbestos exposure in lung cancer and mesothelioma.