Asbestos Concentrations Research Articles

Structurally controlled growth of fibrous amphibole in tectonized metagabbro: constraints on asbestos concentrations in non-serpentinized rocks

The nucleation and concentration of asbestos in rocks are mostly associated with mechanisms of fibre formation, combined with the water-dependent mineralogical alteration produced during the serpentinization of ultramafic masses. Very little is known about the structural settings and tectonic histories that influence and control the occurrence of asbestos in non-serpentinized rocks diffusely embedded within tectonized ophiolitic suites. Focusing on a case history provided by a tectonized metagabbro from the Ligurian Alps (northern Italy), a multiscale structural–petrographic approach is used to investigate the relationships between rock fabric and fibrous amphibole growth within the metagabbro. Meso- to microstructural observations are used to document the role of structurally controlled fluid–rock interactions in localizing the growth of fibrous amphibole during ductile-to-brittle shearing (mylonitic foliation to shear veins). A qualitative structural scenario is provided to illustrate the growth of asbestos amphiboles in shear veins during the progression of shear deformation towards semi-brittle rheological conditions. The mechanisms of the structurally controlled growth of fibrous amphibole in non-serpentinized rocks imply an examination of the tectonic boundary conditions that are at the origin of the concentration of asbestos in ophiolitic rocks involved in orogenic belt construction.

The Concentration of Asbestos Fibers in Bulk Samples and Its Variation with Grain Size

The aim of this work was to establish whether asbestos fibers homogeneously occur in the different fractions ground from naturally occurring asbestos lithotypes, and to calculate the contribution of fibers from each fraction to the overall concentration in the sample. Serpentinite, metabasalt, calc-schist, clay, debris material, and soil, were addressed. Grain size fractions below 20 mm were sieved at 2 mm and 0.106 mm; they were then were mechanically milled to obtain powders below 0.106 mm. The three powdered fractions were characterized using a scanning electron microscope coupled with energy dispersive spectroscopy following M.D. 06/09/94. The still in use (in some cases), Italian normative M.D. 161/2012 specifies that analyses must be performed on the <2 mm fraction and the concentration (mg/kg) correlated with the weight of the whole sample <20 mm. However, the fiber counts yielded asbestos concentrations 50–60% lower compared with total asbestos analyses according to the new R.P.D. 120/2017. Consequently, there is a need to standardize the normative worldwide regulations for the management of asbestos-containing materials, by re-evaluation of sample preparation and quantification of asbestos.

Geological Mapping and Characterization of Possible Primary Input Materials for the Mineral Sequestration of Carbon Dioxide in Europe

This work investigates the possible mineral input materials for the process of mineral sequestration through the carbonation of magnesium or calcium silicates under high pressure and high temperatures in an autoclave. The choice of input materials that are covered by this study represents more than 50% of the global peridotite production. Reaction products are amorphous silica and magnesite or calcite, respectively. Potential sources of magnesium silicate containing materials in Europe have been investigated in regards to their availability and capability for the process and their harmlessness concerning asbestos content. Therefore, characterization by X-ray fluorescence (XRF), X-ray diffraction (XRD), and QEMSCAN® was performed to gather information before the selection of specific material for the mineral sequestration. The objective of the following carbonation is the storage of a maximum amount of CO2 and the utilization of products as pozzolanic material or as fillers for the cement industry, which substantially contributes to anthropogenic CO2 emissions. The characterization of the potential mineral resources for mineral sequestration in Europe with a focus on the forsterite content led to a selection of specific input materials for the carbonation tests. The mineralogical analysis of an Italian olivine sample before and after the carbonation process states the reasons for the performed evaluation. The given data serves as an example of the input material suitability of all the collected mineral samples. Additionally, the possible conversion of natural asbestos occurring in minerals as a side effect of the carbonation process is taken into consideration.

Effects of Legal Regulation on Indoor Air Quality in Facilities for Sensitive Populations - A Field Study in Seoul, Korea.

Facilities for sensitive populations have increased in Korea; and its indoor air quality (IAQ) was strictly regulated by the Korean government compared to other facilities. However, merely public facilities on certain level of total floor area were lawfully regulated. This study aims to characterize the indoor environment at facilities for sensitive populations in Korea and investigate the effects of legal regulation on IAQ throughout the duration of 1 year. Sixty facilities for sensitive populations were investigated. Particulate matter (PM10), nitrogen dioxide (NO2), carbon dioxide (CO2), carbon monoxide (CO), total bacteria count (TBC), total volatile organic compound (TVOC), formaldehyde (HCHO), radon (Rn), ozone (O3), asbestos, fine particulate matter (PM2.5), and volatile organic compounds (VOCs) were target pollutants. As a result, none of the rooms' concentration of CO, NO2, O3, Rn, asbestos, and VOCs exceeded the Korean Standard of Indoor Air Quality, while some rooms' concentration of other pollutants exceeded the KSIAQ. Statutory facilities had lower indoor pollutant concentrations and exceedance rates due to efficient ventilation system and the lack of kitchen location within the building, as opposed to non-statutory facilities. In addition, the VOCs had significant differences depending on the number of years it took for the building to be constructed. To reduce the indoor pollutants concentrations, efficient ventilation systems should be installed while controlling the main sources of pollutants. In addition, construction and remodeling using eco-friendly materials should be considered. The standards of IAQ for small size facilities should be included in the KSIAQ in the future.

Petrofacies for the prediction of NOA content in rocks: application to the “Gronda di Genova” tunneling project

Realization of large geo-engineering projects in rocks containing naturally occurring asbestos (NOA) must address several crucial geo-environmental issues, including the design of the construction site, the enforcement of health protection measures and the environmentally responsible spoil management. This leads to a compelling need to develop effective and standard procedures to evaluate the distribution and concentration of NOA in rock volumes. NOA petrofacies are here proposed as an innovative tool to evaluate the asbestos distribution and concentration in complex geological settings. NOA petrofacies are fundamental asbestos-bearing rock types, consisting in recurrent lithological and structural features controlling asbestos occurrence. Here we describe and discuss how the NOA petrofacies approach was utilized in a geo-environmental study for the evaluation of asbestos content in a complex meta-ophiolite suite, which will be crossed by the “Gronda di Genova” highway by-pass project (Genoa, NW Italy). NOA petrofacies were used to predict the distribution and relative abundance of NOA in geologically homogeneous zones characterized by the occurrence of specific NOA minerals.

Serpentinite from Moeche (Galicia, North Western Spain). A Stone Used for Centuries in the Construction of the Architectural Heritage of the Region

Serpentinites are characterized by highly variable mineralogical, physical, and mechanical properties. Serpentinites from Moeche (North Western Spain) have been studied to establish their mineralogical, petrographic, and textural characteristics, as well as their physical and mechanical parameters and the factors influencing rock failure, to evaluate the possible use of these rocks either for new construction or for conservation-restoration of the architectonic heritage of the region. In this paper, we highlight the importance of a detailed mineralogical and petrographic characterization in the fracture zones, which will determine the viability of quarrying the stone. A strong correlation between the petrographic features and the uniaxial compression strength values has been observed. The most important aspects were found to be the rock texture, the mineralogical composition of the fracture area and foliation, although mineralogy was also found to be involved (% of carbonates) in the strength of the stone. An important preliminary result of the study was the low asbestos content of these serpentinites, which will help in the potential re-opening of the quarries.

Potential Airborne Asbestos Exposure and Risk Associated with the Historical Use of Cosmetic Talcum Powder Products

Over time, concerns have been raised regarding the potential for human exposure and risk from asbestos in cosmetic-talc-containing consumer products. In 1985, the U.S. Food and Drug Administration (FDA) conducted a risk assessment evaluating the potential inhalation asbestos exposure associated with the cosmetic talc consumer use scenario of powdering an infant during diapering, and found that risks were below levels associated with background asbestos exposures and risk. However, given the scope and age of the FDA's assessment, it was unknown whether the agency's conclusions remained relevant to current risk assessment practices, talc application scenarios, and exposure data. This analysis updates the previous FDA assessment by incorporating the current published exposure literature associated with consumer use of talcum powder and using the current U.S. Environmental Protection Agency's (EPA) nonoccupational asbestos risk assessment approach to estimate potential cumulative asbestos exposure and risk for four use scenarios: (1) infant exposure during diapering; (2) adult exposure from infant diapering; (3) adult exposure from face powdering; and (4) adult exposure from body powdering. The estimated range of cumulative asbestos exposure potential for all scenarios (assuming an asbestos content of 0.1%) ranged from 0.0000021 to 0.0096 f/cc-yr and resulted in risk estimates that were within or below EPA's acceptable target risk levels. Consistent with the original FDA findings, exposure and corresponding health risk in this range were orders of magnitude below upper-bound estimates of cumulative asbestos exposure and risk at ambient levels, which have not been associated with increased incidence of asbestos-related disease.

Asbestos exposure and mesothelioma mortality among atomic veterans

Background The United States (U.S.) conducted 230 above-ground atmospheric nuclear weapons tests between 1945 and 1962 involving over 250,000 military personnel. This is the first quantitative assessment of asbestos-related mesothelioma, including cancers of the pleura and peritoneum, among military personnel who participated in above-ground nuclear weapons testing. Methods Approximately 114,000 atomic veterans were selected for an epidemiological study because they were in one of eight series of weapons tests that were associated with somewhat higher personnel exposures than the other tests and because they have been previously studied. We were able to categorize specific jobs into potential for asbestos exposure based on a detailed database of the military activities of the atomic veterans. Standardized mortality ratios (SMR) were calculated by service, rank (officer/enlisted) and ratings (occupation code and work location aboard ship) after 65 years of follow-up. Results Mesothelioma deaths were significantly increased overall (SMR 1.56; 95% CI 1.32–1.82; n = 153). This increase was seen only among those serving in the PPG (SMR 1.97; 95% CI 1.65–2.34; n = 134), enlisted men (SMR 1.81; 95% CI 1.53–2.13; n = 145), and the 70,309 navy personnel (SMR 2.15; 95% CI 1.80–2.56; n = 130). No increased mortality rates were seen among the other services: army (SMR 0.45), air force (SMR 0.85), or marines (SMR 0.75). Job categories with the highest potential for asbestos exposure (machinist’s mates, boiler technicians, water tender, pipe fitters, and fireman) had an of SMR 6.47. Job categories with lower potential (SMR =1.35) or no potential (SMR =1.28) for asbestos exposure had non-significantly elevated mesothelioma mortality. Conclusions The large excess of mesothelioma deaths seen among atomic veterans was explained by asbestos exposure among enlisted naval personnel. The sources of exposure were determined to be on navy ships in areas (or with materials) with known asbestos content. No excess of mesothelioma was observed in other services or among naval personnel with minimal exposure to asbestos in this low-dose radiation exposed cohort.

Asbestos in fresh water fish of a pond in Milan. Where is it coming from

«Asbestos in fresh water fish of a pond in Milan. Where is it coming from?».Introduction:Cement-based material containing asbestos was found in the water of a pond in the city of Milan, Italy, where recreational fishing activities take place. Some fishes are in ‘no-kill’ fishing areas, others are caught and consumed.Objective:To verify the presence of asbestos in water, sediments and some fish species living in the pond. To verify the presence of asbestos in fish feed and to test fish exposure by ingestion.Methods:Samples of water, sediments, fish feed and fish species have been collected and the presence of asbestos fibers has been ascertained in the different matrices.Results:No traces of asbestos were found in water. Instead, the asbestos content in sediments was beyond regulatory limits. Asbestos was detected also in benthic fish species, and in rainbow trout (Oncorhynchus mykiss) that does not reproduce in the pond but must be restocked periodically through aquaculture. In the meat of the grass carp (Ctenopharyngodon idella) 36,000,000 fibers/100 g of wet cloth have been found. Values up to 15,000,000 ff/100 g of wet cloth have been detected in the rainbow trout. Asbestos has also been found in animal feeds, in particular crocidolite fibers and asbestos tremolite bundles.Conclusions:Benthic fish species have likely been contaminated by their close contact with the polluted bottom of the pond. Instead, the presence of asbestos in the trout is probably linked to a previous contamination during farming, since this fish spend a brief period of time in the water of the pond. Asbestos distribution and concentration exclude a risk for public health; however, some values of asbestos found in fish meat deserve attention. Accordingly, precautionary indications have been given to the Municipality of Milan and to the fishermen association. A larger scale monitoring of water, food and animal feed is worth performing to better assess exposure by ingestion.

New comprehensive approach for airborne asbestos characterisation and monitoring.

High concentrations of airborne asbestos in the ambient air are still a serious problem of air quality in numerous localities around the world. Since 2002, elevated concentrations of asbestos minerals of unknown origin have been detected in the ambient air of Pilsen, Czech Republic. To determine the asbestos fibre sources in this urban air, a systematic study was conducted. First, 14 bulk dust samples were collected in Pilsen at nine localities, and 6 bulk samples of construction aggregates for gravel production were collected in a quarry in the Pilsen-Litice district. The quarry is the largest quarry in the Pilsen region and the closest quarry to the built-up urban area. X-ray diffraction of the asbestos minerals revealed that monoclinic amphibole (MA, namely actinolite based on subsequent SEM-EDX analysis) in the bulk samples accounted for < 1-33% of the mass and that the highest values were found in the bulk dust samples from the railway platform of the Pilsen main railway station. Simultaneously, 24-h samples of airborne particulate matter (PM) at three localities in Pilsen were collected. Actinolite was identified in 40% of the PM samples. The relationship between the meteorology and presence of actinolite in the 24 PM10 samples was not proven, probably due to the long sampling integration time. Therefore, highly time-and-size-resolved PM sampling was performed. Second, sampling of size-segregated aerosols and measurements of the wind speed (WS), wind direction (WD), precipitation (P) and hourly PM10, PM2.5 and PM1 were conducted in a suburban locality near the quarry in two monthly highly time-resolved periods (30, 60, 120min). Three/eight PM size fractions were sampled by a Davis Rotating-drum Uniform-size-cut Monitor (3/8DRUM) and analysed for the presences of asbestos fibres by scanning electron microscopy with energy dispersive x-ray spectroscopy (SEM-EDX). Asbestos fibre detection in highly time-resolved PM samples and current WD and WS determination allows the apportionment directionality of asbestos fibre sources. The number of critical actinolite asbestos fibres (length ≥ 5μm and width < 3μm, 3:1) increased with the PM1-10/PM10 and PM2.5-10/PM10 ratios, WS > 2ms-1 and precipitation < 1mm. Additionally, the number of critical actinolite asbestos fibres was not related to a specific WD. Therefore, we conclude that the sources of airborne critical actinolite asbestos fibres in Pilsen's urban area are omnipresent. Frequent use of construction aggregates and gravel from the metamorphic spilite quarries in the Pilsen region and in many localities around the urban area is a plausible explanation for the omnipresence of the critical actinolite asbestos fibres concentration in Pilsen's ambient air. Mitigation strategies to reduce the concentrations of critical actinolite asbestos fibres must be developed. Continuous monitoring and performing SEM-EDX analysis of highly time-and-size-resolved PM samples, correlated with fast changing WS and WD, seems to be a strong tool for efficiently controlling the mitigation strategies of critical actinolite asbestos fibres.

Asbestos Exposure and the Mesothelioma Incidence in Poland.

Asbestos is carcinogenic to humans; the exposure to asbestos causes a wide range of diseases. Aim: Malignant mesothelioma (MM) is unique for asbestos exposure. Methods: Based on the physical inventory of asbestos-cement roofing, the social-economic situation of communes, the proximity of asbestos manufacturing plants, the land use data referring to the surface of the built-up area, and the historical data on the annexations, the amount of asbestos-containing products in use was estimated by computing best Random Forest models. Per capita asbestos use is an indicator to compare the state of asbestos use among countries. MM cases in the local administrative units (provinces) were tested by the application of Moran’s I and Getis and Ord statistic. Results: The total amount of asbestos roofing in Poland was estimated at 738,068,000 m2 (8.2 million tons). In total there were 28 plants in Poland located in 11 provinces throughout the country. The amount of asbestos-cement roofing in use is correlated primarily with the measurements of asbestos concentration fibers (rs = 0.597). MM raw morbidity rate was calculated, stratified by province, and classified into five groups with respect to incidence. Hotspots of MM cases are in the southern part of Poland. Conclusions: MM cases are concentrated in the same geographical areas, which may indicate an increasing impact of environmental exposure. The results of the local and global autocorrelation clearly indicate a statistically significant relationship between incidences of MM in provinces. Poland and other Eastern European countries are among countries with low MM incidence rate. Detailed investigation is desirable since the current MM morbidity rate in Poland seems to be underestimated.

Innovative unattended SEM-EDS analysis for asbestos fiber quantification

Scanning electron microscopy with energy dispersive spectrometry (SEM-EDS) is the only affordable analytical technique that can discriminate both morphology and elemental composition of inorganic fibers. SEM-EDS is indeed required to quantify asbestos in confounding natural matrixes (e.g. ophiolites), but is also time-consuming, operator dependent, and strongly relies on the stochastic distribution of the fibers on the filter surface. The balance between analytical time/cost and the method sensibility allows only about 0.5% of the filter to be analyzed, strongly affecting the statistical significance of results. To improve sensitivity and precision and enhance productivity, an unattended quantitative measurement of the asbestos fibers by SEM-EDS is proposed. The method identifies the particle shape first and determines their chemical composition later, saving EDS analytical time. Our approach was tested on four asbestos standards and the relative error on replicated measurements was < 10%. The proposed unattended method quantifies asbestos in natural confounding matrix, also with a very low asbestos content.

Monitoring and Simulating Environmental Asbestos Dispersion from a Textile Factory.

Although workplace asbestos concentrations (AC) have been reported several times, the past environmental AC are relatively poorly studied. Due to the harmful effects of the asbestos industry, production has moved from early industrialized countries (Japan), to late industrialized countries (Korea), and finally to industrializing countries (Indonesia). The purpose of this study was to determine current occupational exposure levels and evaluate neighborhood environmental exposure levels in an Indonesian asbestos textile factory through collaboration among three generation of industrialized countries. Asbestos concentrations were measured inside and outside of the factory and compared with simulated data. ACs in the factory were similar to those of 1980s and 1990s levels in the Korean factory that transferred the machines. Environmental ACs were dispersed according to wind direction. There were no significant differences between monitored and simulated data, and correlation coefficients between downwind, upwind, and middle wind directions were high, with some statistical significance. This study can be used to estimate past environmental ACs to understand the causality of asbestos related diseases. Because of the small sample size and specific weather conditions, a large-scale study of various asbestos exposure sources, including asbestos cement factories, shipyards, and mines, and various atmospheric conditions is required.

Naturally occurring asbestos: Validation of PCOM quantitative determination

The quantitative determination of the content of asbestos in rock matrices is a complex operation that is susceptible to significant errors. The principal instruments used for the analysis are the Scanning Electron Microscope (SEM) and the Phase Contrast Optical Microscope (PCOM). Although the PCOM resolution is inferior than that of SEM (0.5 µm VS 1 nm), PCOM analysis has several advantages, including more representativity of the analyzed sample, more effective recognition of chrysotile and a lower cost. The PCOM error evaluation generally provided by analysis laboratories varies between 50% and 150%. There are not, however, enough specific studies that discuss every error in addition to the instrumental error or that link them to the asbestos content in rock samples. Our work aims to provide a validation of a methodology for the determination of the total content of asbestos using PCOM. The threshold for asbestos concentration in soils is 1000 mg/kg, as defined by Italian law in force. (D. Lgs. 152, 2006).

Joint Iranian-Russian studies of airborne asbestos concentrations in Tehran, Iran, in 2017

Assessment of airborne asbestos in urban areas of Tehran is important due to its potential health risks posed by a significant excess of current standards. Determination of airborne fibers can be performed using Phase Contrast Microscopy (PCM) as well as such a modern technique as Facade pane and its spectrum (SEM). Since PCM cannot differentiate asbestos and non-asbestos fibers, SEM is recommended to monitor the airborne asbestos content. The objective of this study was to determine asbestos fiber concentrations in ambient air in different areas of Tehran. Following the collection of samples using standard methods, we determined all fiber counts using PCM and asbestos fiber counts using SEM with X-ray diffraction microanalysis. The study results were then compared to the data related to the past six years obtained from the Air Quality Control Company (Iran) conducting annual airborne dust measurements in residential areas of Tehran using PCM. It should be noted that the scope of activities of the Air Quality Control Company did not include differentiation of asbestos from non-asbestos fibers.According to the results, all airborne fibrous particles sampled were either organic or mineral fibers, the appearance and specter of which were different from those of asbestos. Filter loading with mineral and organic fibers as well as soot particles from automobile exhausts indicated generally high ambient air pollution at all sampling sites. Optical and electron microscopy analyses of five dust samples collected from horizontal outdoor surfaces detected no asbestos fibers. We recommend regular monitoring of ambient air pollution in the streets of Tehran at different seasons of the year and establishing asbestos fiber concentrations using scanning electron microscopy for complete characterization of air pollution.

Evaluation of airborne asbestos exposure from routine handling of asbestos-containing wire gauze pads in the research laboratory

Three independently conducted asbestos exposure evaluations were conducted using wire gauze pads similar to standard practice in the laboratory setting. All testing occurred in a controlled atmosphere inside an enclosed chamber simulating a laboratory setting. Separate teams consisting of a laboratory technician, or technician and assistant simulated common tasks involving wire gauze pads, including heating and direct wire gauze manipulation. Area and personal air samples were collected and evaluated for asbestos consistent with the National Institute of Occupational Safety Health method 7400 and 7402, and the Asbestos Hazard Emergency Response Act (AHERA) method. Bulk gauze pad samples were analyzed by Polarized Light Microscopy and Transmission Electron Microscopy to determine asbestos content. Among air samples, chrysotile asbestos was the only fiber found in the first and third experiments, and tremolite asbestos for the second experiment. None of the air samples contained asbestos in concentrations above the current permissible regulatory levels promulgated by OSHA. These findings indicate that the level of asbestos exposure when working with wire gauze pads in the laboratory setting is much lower than levels associated with asbestosis or asbestos-related lung cancer and mesothelioma.

Polarized light microscope method for the determination of asbestos fiber of textile

ABSTRACTOptical spectrogram and optical characteristic parameters of six kinds of asbestos standard products were established by polarizing microscope to analyze the asbestos fiber, and utilized horizon estimation to get the semi-quantitative asbestos content in the samples. The sample had been observed form, refractive index, interference color, dispersion, ductility, color, pleochroism, cleavage, contour lines, bumps, rough, baker characteristics under different refractive index of oiled, to compare with standard optical spectra and characteristic parameters. Comparison between the situation of asbestos fiber particles and the standard map of mineral chips in the field of view, the percentage of asbestos fibers in the sample is estimated. The results showed that this method is accurate, simple and fast.

DNA methylation profiling of asbestos-treated MeT5A cell line reveals novel pathways implicated in asbestos response.

Occupational and environmental asbestos exposure is the main determinant of malignant pleural mesothelioma (MPM), however, the mechanisms by which its fibres contribute to cell toxicity and transformation are not completely clear. Aberrant DNA methylation is a common event in cancer but epigenetic modifications involved specifically in MPM carcinogenesis need to be better clarified. To investigate asbestos-induced DNA methylation and gene expression changes, we treated Met5A mesothelial cells with different concentrations of crocidolite and chrysotile asbestos (0.5 ÷ 5.0µg/cm2, 72h incubation). Overall, we observed 243 and 302 differentially methylated CpGs (≥ 10%) between the asbestos dose at 5µg/cm2 and untreated control, in chrysotile and crocidolite treatment, respectively. To examine the dose-response effect, Spearman's correlation test was performed and significant CpGs located in genes involved in migration/cell adhesion processes were identified in both treatments. Moreover, we found that both crocidolite and chrysotile exposure induced a significant up-regulation of CA9 and SRGN (log2 fold change > 1.5), previously reported as associated with a more aggressive MPM phenotype. However, we found no correlation between methylation and gene expression changes, except for a moderate significant inverse correlation at the promoter region of DKK1 (Spearman rho = - 1, P value = 0.02) after chrysotile exposure. These results describe for the first time the relationship between DNA methylation modifications and asbestos exposure. Our findings provide a basis to further explore and validate asbestos-induced DNA methylation changes, that could influence MPM carcinogenesis and possibly identifying new chemopreventive target.

Past and current asbestos exposure and future mesothelioma risks in Britain: The Inhaled Particles Study (TIPS)

BackgroundOccupational and environmental airborne asbestos concentrations are too low and variable for lifetime exposures to be estimated reliably, and building workers and occupants may suffer higher exposure when asbestos in older buildings is disturbed or removed. Mesothelioma risks from current asbestos exposures are therefore not known.MethodsWe interviewed and measured asbestos levels in lung samples from 257 patients treated for pneumothorax and 262 with resected lung cancer, recruited in England and Wales. Average lung burdens in British birth cohorts from 1940 to 1992 were estimated for asbestos-exposed workers and the general population.ResultsRegression analysis of British mesothelioma death rates and average lung burdens in birth cohorts born before 1965 suggests a lifetime mesothelioma risk of approximately 0.01% per fibre/mg of amphiboles in the lung. In those born since 1965, the average lung burden is ∼1 fibre/mg among those with no occupational exposure.ConclusionsThe average lifetime mesothelioma risk caused by recent environmental asbestos exposure in Britain will be about 1 in 10 000. The risk is an order of magnitude higher in a subgroup of exposed workers and probably in occupants in the most contaminated buildings. Further data are needed to discover whether asbestos still present in buildings, particularly schools, is a persistent or decreasing hazard to workers who disturb it and to the general population, and whether environmental exposure occurs predominantly in childhood or after beginning work. Similar studies are needed in other countries to estimate continuing environmental and occupational mesothelioma hazards worldwide, including the contribution from chrysotile.

Framework for assessment and phytoremediation of asbestos-contaminated sites.

We examine the feasibility of phytoremediation as an alternative strategy to limit the exposure of asbestos in site with asbestos-containing materials. We collected soils from four locations from two sites-one with naturally occurring asbestos, and another, a superfund site, where asbestos-containing materials were disposed over decades-and performed ecotoxicology tests. We also performed two experiments with crop cultivar and two grasses from serpentine ecotype and cultivar to determined best choice for phytoremediation. Asbestos concentrations in different size fractions of soils varied by orders of magnitude. However, different asbestos concentrations had little effect on germination and root growth. Presence of co-contaminants such as heavy metals and lack of nutrients affected plant growth to different extents, indicating that several of these limiting factors should be considered instead of the primary contaminant of concern. Crop cultivar survived on asbestos-contaminated soil. Grasses from serpentine ecotype did not show higher biomass than the cultivar. Overall, these results showed that soil conditions play a critical role in screening different crop species for phytoremediation and that asbestos concentration has limited to no effect on plant growth. Our study provided a framework for phytoremediation of asbestos-contaminated sites to limit long-term asbestos exposure.