Release Of Asbestos Fibers Research Articles

Asbestos Hazard in Serpentinite Rocks: Influence of Mineralogical and Structural Characteristics on Fiber Potential Release

Naturally occurring asbestos (NOA) represents a matter of social and environmental concern due to its potential release in the atmosphere during rock excavation and grinding in quarry and road tunnel activities. In most cases, NOA occurs in serpentinites, i.e., rocks deriving from low-grade metamorphic hydration of mantle peridotites. The potential release of asbestos fibers from serpentinite outcrops depends on several features, such as serpentinization degree, rock deformation, weathering, and abundance of fibrous veins. In this study, we selected a set of serpentinite samples from a representative outcrop in Tuscany (Italy), and we analyzed them by Optical, Scanning, and Transmission Electron Microscopies. The samples were treated by grinding tests following the Italian guidelines Decrees 14/5/96 and 152/2006 for the determination of the Release Index (RI), i.e., the fiber amount released through controlled crushing tests. The fine-grained powder released during the tests was analyzed by quantitative Fourier transform infrared spectroscopy (FTIR) to determine the variety and the amount of released fibers and to assess the potential hazard of the different serpentinite samples. Results indicate that the amount of released fibers is mostly related to serpentinite deformation, with the highest RI values for cataclastic and foliated samples, typically characterized by widespread occurrence of fibrous veins. Conversely, massive pseudomorphic serpentinite revealed a very low RI, even if their actual chrysotile content is up to 20–25%. Based on our original findings from the RI results, a preliminary investigation of the outcrop at the mesoscale would be of primary importance to obtain a reliable hazard assessment of NOA sites, allowing the primary distinction among the different serpentinites lithotypes and the effective fiber release.

Physicochemical analysis of primers and liquid membranes as asbestos’ encapsulant

Asbestos-containing materials pose significant health risks due to the potential dispersion of harmful fibers into the environment. This study presents a comprehensive physicochemical analysis of coatings, including primers and liquid membranes, designed to be applied on asbestos cement roofs, aiming to prevent the release of asbestos fibers and safeguard human health. Primers are normally used during the process of removing asbestos-containing panels to minimize the dispersion of fibers in the environment. By encapsulating the fibers on the surface, the primer helps to reduce the risk of fiber release during handling and removal. On the other hand, the primary goal of a liquid membrane is to encapsulate the asbestos fibers permanently, for long-term protection, preventing the potential health risks associated with asbestos exposure.To assess the reliability of primers and membranes is a matter of great importance especially for developing counties which have recently forbidden or are in the prohibition phase for the use of asbestos fibers. Two primers and two liquid membranes were investigated in a certified laboratory through a series of chemical and physical analysis. A primer was taken from commercial products in Colombia, a country that forbids asbestos but does not have legislation on these products, while two primers and a membrane were taken from a European country with high standards and decades of experience in the production of these materials to prevent asbestos exposure. The solid content, ash content, determination of primary solvents, thermogravimetry, infrared spectrum (FT-IR) of the polymer, infrared spectrum (FT-IR) of powders (fillers and pigments), and density were analyzed in the four products. Additionally, the membranes underwent testing for heat resistance, resistance to rain and freeze-thaw cycles, water impermeability, and accelerated aging (UVA 340, 1000 h). Furthermore, on membranes, adhesion capability (pull-off) was tested before and after heat-rain, freeze-thaw, UV ageing tests to ensure a durable bond between the coating and the asbestos surface.The results of the investigation revealed promising findings for both the primer and liquid membrane formulations. The primer demonstrated its potential applicability during the removal of asbestos panels, offering a preliminary safeguard against fiber dispersion. On the other hand, the liquid membranes exhibited excellent properties in encapsulating asbestos fibers effectively, providing long-term protection to the substrate. The Colombian membrane shown a calcium carbonate basis for the inorganic filler, with an almost pure acrylic polymer, while the second membrane shown a polymer styrene-acrylic matrix. This leads to less elasticity for the first membrane, and a possible exposure to acid rain attacks. Nevertheless, this chemical difference did not alter the results of the aging tests.

Risk assessment of asbestos containing materials in a deteriorated dwelling area using four different methods

The release of asbestos fibers in old buildings, during demolition, or remodeling is associated with severe public health risks to building occupants and workers. In Korea, asbestos was used in several building materials during the 20th century. Although the use of asbestos is currently banned, its widespread earlier use and the current government initiatives to revitalize dilapidated areas make it essential to accurately evaluate the location and status of asbestos-containing materials (ACMs). This study surveyed buildings in an area of deteriorated dwellings targeted for renewal and determined the status and distribution of ACMs in that area. Asbestos distribution maps were generated and asbestos characteristics were analyzed. In addition, the risk posed by the identified ACMs was assessed using four international methods (the Korean Ministry of Environment, US Environmental Protection Agency, American Society for Testing and Materials, and UK Health and Safety Executive methods), and the results were compared. Notable differences between the assessment results were identified and were found to reflect the specific characteristics of buildings in the study area. These findings suggest ACM risk assessments should be specifically tailored to the regions in which they are applied, thereby improving ACM management and promoting both worker and occupant health.

Management of Naturally Occurring Asbestos Area in Republic of Korea

ABSTRACT The Republic of Korea Government has adopted a whole-of-government approach in the management of naturally occurring asbestos (NOA) through a nationwide asbestos management plan. Regional and detailed mapping, and examination of NOA effects are still ongoing for NOA management by indoor air, noise and asbestos management division, Ministry of Environment. Plans by the Korea Rail Network Authority are under way to rebuild the Janghang double-track railway. The proposed Jannghang double-track railway route is through an area of high NOA probability that has serpentine and ultramafic rock. Chrysotile, tremolite, and actinolite asbestos were among the rocks identified within the project site (initial planning line and the operational design line). The level of asbestos in most soils was low (≤0.25 percent), while some soils contained 0.75 percent asbestos. Monitoring and analyses of air quality revealed below 0.01 fibers per cm3 (f/cc). However, there were no traces of asbestos detected in the groundwater and stream water. Despite the low asbestos content of the soil and rock, the disturbance of NOA-containing soils and rocks during railway construction could trigger the release of asbestos fibers into the air. NOA mitigation plans and measures are necessary for workers and residents during the construction of the railway.

Assessment of Naturally Occurring Asbestos in the Area of Episcopia (Lucania, Southern Italy)

Over the last few years, the risk to human health related to asbestos fiber exposure has been widely demonstrated by many studies. Serpentinites are the main rocks associated with naturally occurring asbestos (NOA). In order to investigate the presence of NOA, a mineralogical study was conducted on eleven serpentinite samples collected nearby the village of Episcopia (Lucania, Southern Italy). Various analytical techniques such as X-ray powder diffraction (XRPD), scanning electron microscopy combined with energy dispersive spectrometry (SEM-EDS) and derivative thermogravimetry (DTG) were used to determine the occurrence of asbestos minerals and to make morphological observations. Results pointed out that all of the samples contain asbestos minerals (e.g., tremolite, actinolite and chrysotile). Moreover, it was observed that both natural processes and human activity may disturb NOA-bearing outcrops and provoke the formation of potentially inhalable airborne dust causing the release of asbestos fibers into the environment, thereby increasing the risk to human health. For this reason, our study aims to highlight the requirement of a natural asbestos survey and periodic update in the area.

Evaluation of take-home exposure to asbestos from handling asbestos-contaminated worker clothing following the abrasive sawing of cement pipe

Although industrial uses of asbestos have declined since the 1970s, in recent years there has been a renewed interest in para-occupational (“take-home”) exposure to these fibers. The aim of this study was to quantify the release of asbestos fibers, if any, during the shaking out of crocidolite- and chrysotile-contaminated clothing in a simulated at-home setting. An exposure study was conducted in which personal and area air samples were collected during the handling (i.e. shake-out) of work clothing (shirt and pants) previously worn by an operator who had cut asbestos-containing cement pipe. During eight “loading” events, the operator cut a historically representative asbestos-containing cement pipe (10% crocidolite and 25% chrysotile) using a powered abrasive saw. Subsequently, 30-minute air samples were collected during four “shake-out” events, each of which consisted of the handling of two complete sets of contaminated work clothes. Samples were analyzed in accordance with NIOSH methods 7400 and 7402. The mean phase contrast microscopy equivalent (PCME) airborne concentrations were 0.52 f/cc (SD = 0.34 f/cc) for total asbestos fibers, 0.36 f/cc (SD = 0.26 f/cc) for chrysotile and 0.17 f/cc (SD = 0.096 f/cc) for crocidolite. Based on likely estimates of the frequency of laundering activities, and assuming that the dusty clothing (1) is not blown off in the occupational setting using compressed air and (2) is not shaken out before entering the home, a family member handling the clothing could potentially have a lifetime cumulative exposure to chrysotile and crocidolite of approximately 0.20 f/cc-year and 0.096 f/cc-year, respectively.

Assessment of asbestos exposure during a simulated agricultural activity in the proximity of the former asbestos mine of Balangero, Italy

The natural occurrence of asbestos (NOA) in rural areas is a serious concern for human health and the dispersion route of asbestos in the proximity of natural asbestos-rich settings has been marginally evaluated so far. NOA may affect air, but also water and soil quality. In rural areas population may be exposed to asbestos with a largely unknown impact on human health. This work investigates the potential exposure of a farmer cultivating a field nearby the largest former asbestos mine of Western Europe (Balangero, Italy). The concentration of waterborne asbestos in the stream used to water the field was measured (ca. 2×105 fibers per liter, ff/L) and the cultivated ultramafic topsoil characterized, evidencing a remarkable occurrence of chrysotile. The worker’s personal exposure and the environmental fiber dispersion during a simulated agricultural activity (tillage) were quantified in two independent trials. During the trials, the worker was exposed to average concentrations of 16 and 26ff/L, with a peak of 40ff/L. These data inform about the possible exposure of an agricultural worker to asbestos concentration higher than the accepted threshold of 2ff/L. The release of asbestos fibers into the environment was negligible (0–2ff/L).

석면함유 건축물의 석면 노출 및 위해성 평가

This study was performed to evaluate the asbestos exposure levels and to calculate excess lifetime cacer risks(ELCRs) in asbestos-containing buildings for maintenance and management. The range of airborne asbestos concentration of 33 buildings was 0.0018 ~ 0.0126 f/cc and one site exceeded indoor air-quality recommended limit 0.01 f/cc. And ELCRs based on US EPA IRIS(Integrated risk information system) model are 1.5E-06 ~ 3.9E-05 levels, and there was no site showed 1.0E-04 (one person per million) level or more, and 11 sites showed 1.0E-05 (one person per 100,000 people) level or more. To prevent the release of asbestos fibers, it needs operation and maintenance of asbestos-containing building materials, and there are some methods such as removal, repairment, enclosure and encapsulation. In conclusion, a risk-based air action level for asbestos in air is an appropriate metric for asbestos-containing building management.

Chrysotile Asbestos and Mesothelioma

Vol. 118, No. 7 PerspectivesOpen AccessChrysotile Asbestos and Mesothelioma Richard A. Lemen Richard A. Lemen Search for more papers by this author Published:1 July 2010https://doi.org/10.1289/ehp.1002446AboutSectionsPDF ToolsDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InReddit The Editor’s Summary for the article by Tse et al. (2010) stated the following:Assuming an average latency of 42 years, the authors predict that incidence rates will peak in 2009 and that diagnoses will peak in 2014. However, they caution that ongoing use of chrysotile asbestos (which has been implicated but not conclusively established as a cause of mesothelioma) and the release of asbestos fibers from older buildings during demolition or renovation may slow the projected decline.The statement concerning chrysotile asbestos being “implicated but not conclusively established as a cause of mesothelioma” is inconsistent with current scientific opinion. I refer you to the most recent evaluation by the International Agency for Research on Cancer in which Straif et al. (2009) stated,Epidemiological evidence has increasingly shown an association of all forms of asbestos (chrysotile, crocidolite, amosite, tremolite, actinolite, and anthophyllite) with an increased risk of lung cancer and mesothelioma. Although the potency differences with respect to lung cancer or mesothelioma for fibres of various types and dimensions are debated, the fundamental conclusion is that all forms of asbestos are “carcinogenic to humans” (Group 1).In addition, opinions such as that expressed in the Editor’s Summary are advanced only by scientists with prochrysotile industry bias.When I wrote the draft for the first IARC Monograph on asbestos in 1976, which the expert committee accepted and published in 1977 as IARC Monograph Volume 14, a similar conclusion was stated: “Many pleural and peritoneal mesotheliomas have been observed after occupational exposure to crocidolite, amosite and chrysotile.” Since then—more than 30 years—science has not changed its opinion that all forms of asbestos, including chrysotile, cause mesothelioma.In fact, in the article that is the subject of the Editor’s Summary, Tse et al. (2010) did not indicate that chrysotile is not a cause of mesothelioma; on the contrary, they stated the following:Although the mesothelioma incidence is anticipated to decline in the coming decades, it may not decrease to background risk levels given that chrysotile consumption has not been banned under the current legislation and that secondary asbestos exposure from the environment will likely continue. Nevertheless, the hypotheses generated from this ecologic study need further confirmation by subsequent analytic studies. The present study provides supportive evidence for an immediate and global ban on asbestos use.I hope that future Editor’s Summaries will reflect the conclusions of the article and not put forth statements that are not supported by mainstream science. I also support the conclusion of Tse e al. (2010) for “an immediate and global ban on asbestos use.”Editor’s Note: We appreciate Lemen’s concern about the incorrect statement that was included in the original Editor’s Summary for Tse et al. (2010), and we regret the error. The Editor’s Summary has been corrected in the online version of the paper, and an erratum was published in the June issue of EHP [118:A240 (2010)]; the text of the erratum is included below:The Editor’s Summary for the article “Are Current or Future Mesothelioma Epidemics in Hong Kong the Tragic Legacy of Uncontrolled Use of Asbestos in the Past?” by Tse et al. [Environ Health Perspect 118:382–386 (2010); doi:10.1289/ehp.0900868], has been corrected online: specifically, “(which has been implicated but not conclusively established as a cause of mesothelioma)” has been deleted.The author testifies in asbestos litigation on behalf of plaintiffs.ReferencesIARC. 1977. Asbestos. IARC Monogr Eval Carcinog Risk Hum 14:1-106. Google ScholarStraif K, Benbrahim-Tallaa L, Baan R, Grosse Y, Secretan B, El Ghissassi Fet al.. 2009. A review of human carcinogens—part C: metals, arsenic, dusts, and fibres. Lancet Oncol 10:453-45419418618. Crossref, Medline, Google ScholarTse LA, Yu IT, Goggins W, Clements M, Wang XR, Au JSet al.. 2010. Are current or future mesothelioma epidemics in Hong Kong the tragic legacy of uncontrolled use of asbestos in the past?Environ Health Perspect 118:382-38620064790. Link, Google ScholarFiguresReferencesRelatedDetails Vol. 118, No. 7 July 2010Metrics About Article Metrics Publication History Originally published1 July 2010Published in print1 July 2010 Financial disclosuresPDF download License information EHP is an open-access journal published with support from the National Institute of Environmental Health Sciences, National Institutes of Health. All content is public domain unless otherwise noted. Note to readers with disabilities EHP strives to ensure that all journal content is accessible to all readers. However, some figures and Supplemental Material published in EHP articles may not conform to 508 standards due to the complexity of the information being presented. If you need assistance accessing journal content, please contact [email protected]iehs.nih.gov. Our staff will work with you to assess and meet your accessibility needs within 3 working days.

Are Current or Future Mesothelioma Epidemics in Hong Kong the Tragic Legacy of Uncontrolled Use of Asbestos in the Past?

BackgroundBecause of the long latent period of asbestos-related mesothelioma, investigators suggest that the high incidence of this disease will continue in the coming decades.ObjectivesWe describe the time trends of mesothelioma incidence and its relationship to historical consumption of asbestos in Hong Kong and project future trends of mesothelioma incidence.MethodsWe obtained local annual consumption of total asbestos for 1960–2006 (converted to kilograms per person per year). Age-standardized incidence rates (ASIRs) of mesothelioma were computed and depicted on graphs using the centered moving average method. Indirectly standardized rates were regressed on a transformation of consumption data that assumed that the latency between asbestos exposure and mesothelioma diagnosis followed a normal distribution with a mean ± SD of 42 ± 10.5 years.ResultsASIRs for males started to increase substantially in 1994 and were highest in 2004; for females, ASIRs climbed in the 1980s and in the early 1990s but have fluctuated without obvious trends in recent years. The highest asbestos consumption level in Hong Kong was in 1960–1963 and then decreased sharply afterward. Using past asbestos consumption patterns, we predict that the mesothelioma incidence rate for males will peak in 2009, with the number of cases peaking in 2014, and then slowly decline in the coming decades.ConclusionsHong Kong experienced an epidemic of mesothelioma from 2000 to 2006 that corresponded with the peak of local asbestos consumption in the early 1960s assuming an average latent period of 42 years. The incidence is anticipated to decline in the coming decades but may not decrease back to the background risk level (the risk unrelated to asbestos exposure).

Asbestos Release from Whole-Building Demolition of Buildings with Asbestos-Containing Material

The whole-building demolition method, which entails one-or two-story buildings pushed down by heavy equipment, loaded into trucks, and hauled away, is generally the most cost-effective means to remove small buildings. For taller buildings, a crane and wrecking ball may be used initially to reduce the height of the building. Demolitions might release asbestos fibers from friable asbestos-containing material (ACM). Fibers also might be released from nominally nonfriable ACM (Categories I and II nonfriable ACM) if it becomes friable after rough handling throughout the whole-building demolition process. This paper reports on asbestos air monitoring from two demolition projects involving ACM. In one building, Category II nonfriable ACM was present because it could not be removed safely prior to demolition. Both projects had large quantities of gypsum wallboard with ACM joint compound and ACM flooring. One building had large quantities of ACM spray-on ceiling material. During the demolitions personal air monitoring of the workers and area air monitoring downwind and around the sites were conducted. The monitoring found the concentrations of fibers detected by phase contrast microscopy were generally well below the permissible exposure limits (PEL) of workers. Electron microcopy analysis of samples at or near the PEL indicated most of the fibers were not asbestos, and the actual asbestos exposure was often below the detection limit of the procedure. The buildings were kept wet with fire hoses during the demolition and that required large quantities of water, 20,000–60,000 gal/day (75–225 m3/day). Earlier studies found little asbestos release from buildings containing only nonfriable ACM demolished by this method. This project found a negligible release of asbestos fibers, despite the presence of nonfriable materials that might become friable, such as ACM joint compound and spray-on ACM ceiling coating.

Simulation Tests to Assess Occupational Exposure to Airborne Asbestos from Asphalt-Based Roofing Products

This study sought to evaluate exposure from specific products to evaluate potential risk from roof repair activities. Five asbestos-containing fibered roof coatings and plastic cements, representing a broad range of these types of products, were tested in exposure simulations. These products were applied to representative roof substrates. Release of asbestos fibers during application and sanding of the product shortly thereafter (wet sanding) were tested initially. Other roof substrates were cured to simulate a product that had been on a rooftop for several months and then were tested to evaluate release of fibers during hand sanding and hand scraping activities. Additional tests were also conducted to evaluate asbestos release during product removal from tools and clothing. Two personal (n = 84) and background/clearance (n = 49) samples were collected during each 30-min test and analyzed for total fiber concentration [phase-contrast microscopy (PCM)] and for asbestos fiber count [transmission electron microscopy (TEM)]. PCM concentrations ranged from <0.005 to 0.032 fibers per cubic centimeter (f cc(-1)). Chrysotile fibers were detected in 28 of 84 personal samples collected. TEM concentrations ranged from <0.0021 to 0.056 f cc(-1). Calculated 8-h time-weighted averages (TWAs) ranged from 0.0003 to 0.002 f cc(-1) and were comparable to the background TWA concentration of 0.0002 f cc(-1) measured in this study. Based on these results, it is unlikely that roofers were exposed to airborne asbestos concentrations above the current or historical occupational guidelines during scraping and sanding of these products during roof repair.

Asbestos exposure from gaskets during disassembly of a medium duty diesel engine

Diesel engines have historically used asbestos-containing gaskets leading to concerns of fiber release and mechanic exposure. Other published studies regarding asbestos fiber release during gasket removal have reported on short-duration events; were conducted under simulated work conditions; or had other limitations. There are no comprehensive studies relating to diesel engine gaskets under conditions similar to those reported herein, evaluating asbestos fiber release from gaskets during all facets of a complete disassembly and cleaning of a medium duty diesel engine in a busy repair and service shop by a journeyman mechanic. Asbestos content of all gaskets was identified; all disassembly tasks were described and timed; and personal and area air monitoring was conducted for each task. Twenty seven of thirty three gaskets contained chrysotile asbestos in concentrations that ranged from 5 to 70%. All but one air monitoring sample reported results below the limit of reliable detection even though plumes of visible dust were evident during various removal, cleaning, and buffing procedures. The detection limit for airborne asbestos fibers in this investigation was influenced by the presence of other shop dust in the air. Our investigation demonstrates that using shop-standard procedures in an established repair facility, a journeyman mechanic has very little potential for exposure to airborne asbestos fibers during disassembly of an engine, approximately 10% or less than that currently considered to be acceptable by OSHA.

Fiber release during the removal of asbestos-containing gaskets: a work practice simulation.

Work practice studies were conducted involving the removal of asbestos-containing sheet gaskets from steam flanges. These studies were performed to determine potential exposure levels to individuals who have worked with these types of materials in the past and may still work with these products today. The work practices were conducted inside an exposure characterization laboratory (ECL) and were performed by scraping and wire brushing, chrysotile-containing (65% to 85%) sheet gaskets from a number of used steam flanges. Airborne asbestos levels were measured by phase contrast microscopy (PCM) and transmission electron microscopy (TEM) for the personnel and area air samples collected during the study. These workplace simulations showed substantial asbestos fiber release using scraping, hand wire brushing, and power wire brushing techniques during the gasket removal process. The range of concentration was 2.1 to 31.0 fibers/cc greater than 5 micrometers when measured by PCM. These results contrasted with the few reported results in the published literature where lower airborne asbestos levels were reported. In these studies the airborne asbestos fiber levels measured in many of the samples exceeded all current and historical Occupational Safety and Health Administration (OSHA) excursion limits (15-30 minutes) and some previous permissible exposure limits (PEL) based on eight-hour time-weighted average (TWA) standards. Also, individuals who performed this type of work in the past may have had exposures higher than previously suspected. The results demonstrated that employees who remove dry asbestos-containing gaskets with no localized ventilation should wear a full face supplied air respirator with a HEPA escape canister and the work area should be designated a regulated area.

Characterization of vehicular brake service personnel exposure to airborne asbestos and particulate.

Evaluation of fibers and total particulate generated during the servicing of drum brakes on motor vehicles as well as during the resurfacing (arcing) of brake shoes was conducted. Conditions for the studies were based on review of contemporary (approximately 1950-1980) working practices in the industry. This work was conducted in two parts. Phase 1 estimated the release of asbestos fibers and total particulate during brake inspection and replacement of light-duty vehicle rear drum brakes at an auto/truck repair facility. Two distinct work practices were evaluated: One rear wheel from each vehicle was serviced using compressed air to remove dust while the second rear wheel was serviced without compressed air. Area and personal monitoring of fiber levels demonstrated counts (without compressed air) that ranged from 0.05 to 0.2 f/cc. Fiber counts when using compressed air averaged from 0.05 to 0.9 f/cc. Results from real-time aerosol monitoring indicated elevated dust levels for about 15 minutes after blow out. With shop doors open, dust levels increased to 5.0 mg/m3 at blow out and returned to 0.08 mg/m3 within two minutes. When the shop doors were closed, the dust levels reached 13.5 mg/m3 at blow out and decreased to 1.68 mg/m3 within one minute and to background within 14 minutes. The Phase 2 series evaluated the release of fibers and other particulate from are grinding. For operations conducted under conditions simulating a workplace, a mean of 0.19 f/cc +/- 0.16 was determined. Dust levels averaged 0.25 mg/m3 +/- 0.05. Brake service monitoring in these tests demonstrates that asbestos fiber concentrations, considered on a time weighted average basis, should not exceed currently acceptable workplace standards whether or not the worker uses compressed air, nor during the arc grinding process when arcing is conducted in accord with the design of the equipment.

Asbestos fiber release from the brake pads of overhead industrial cranes.

The purpose of this evaluation was to determine the actual contribution of airborne asbestos fibers to the work environment from the operation of overhead cranes and hoists that use asbestos composition brake pads. The evaluation was conducted in a working manufacturing facility. Other potential sources of asbestos were accounted for by visual inspection and background air monitoring. An overhead crane assembly comprised of a trolley and two hoists was employed for this study. The crane was operated for two consecutive eight-hour shifts representative of a heavy-duty cycle. Forty-four personal and area air samples were collected during the assessment. Asbestos fibers were analyzed for by phase contrast (NIOSH 7400), and transmission electron (NIOSH 7402) microscopy methods. Eight-hour time-weighted average (TWA) asbestos fiber concentrations ranged from < 0.005 to 0.011 fibers/cc (PCM), and < 0.0026 to < 0.0094 f/cc (TEM). There were no asbestos fibers detected by the TEM method from air samples collected during the operation of the cranes.

Release of asbestos fibers during casting ring liner manipulation

Civil lawsuits have been filed that allege wrongful deaths of at least one dentist and one dental technician from asbestos exposure. However, no known published scientific studies support such allegations. To assess what potential exposure could occur, air samples were collected while casting rings were lined with asbestos liner. Fibers were collected on filters and counted by use of phase-contrast microscopy and transmission electron microscopy. The concentrations of fibers 5 microns long or greater on all filters was less than allowed by federal guidelines. Based on this simulation the potential health risk from using asbestos ring liner seems low.

A Study Determining Asbestos Fiber Release during the Removal of Valve Packing

Asbestos packing material used in valves is generally considered to be a nonfriable material unless cut or torn. In a controlled, contained area within a steam power plant, personal and area air samples were collected before and during removal of asbestos packing material from valves that had been used at the plant. The results of this study show asbestos fibers can be released into the air during the generally used procedures for the removal of asbestos packing material. Air concentrations were measured by phase contrast microscopy in the range of 0.2 to 1.3 fibers/cc and by transmission electron microscopy in the range of 1.5 to 4.2 fibers/cc for all diameter fibers greater than 5 μm in length.

Asbestos Fiber Release Associated with Room Humidifiers

Abstract A study was carried out to determine if portable room humidifiers (nebulizing or evaporative types) could aerosolize asbestos fibers from contaminated water. Deionized water seeded with chrysotile fibers obtained from a commercial source (23×106 fibers/L) was added to the humidifiers, which were run for 1 hour in a previously purged, 17-m3, unventilated room. Approximately 3000 L of air from each trial were collected by Gilian Aircon 520 high volume samplers. Simultaneous total particle counts were obtained using a Climet particle counter. Samples were examined by both phase contrast microscopy (PCM) and transmission electron (TEM) microscopy. The evaporative humidifiers did not emit asbestos fibers (≥5 μm in length) detectable by either PCM or TEM. From the nebulizing humidifiers, TEM (but not PCM) detected an average of 5.3 fibers (≥5 μm) per 10 grid squares corresponding to approximately 0.01 fiber/cc of air (range 0.0077-0.0140). Results provide evidence that asbestos fibers can be emitted by...

EVALUATION OF EROSION RELEASE AND SUPPRESSION OF ASBESTOS FIBERS FROM ASBESTOS BUILDING PRODUCTS

Test methods have been developed to measure the release of asbestos fibers from the surfaces of a range of asbestos building products when subjected to an airstream (air erosion) or to light brush contact (brush erosion). The tests allowed discrimination of differences in fiber release from the products and assessment of the effectiveness of encapsulants in suppressing fiber release. Application of “good” encapsulants (by using tough binders and optimum application rates) reduced fiber release to very low or nondetectable levels for all products tested.