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FILE NAME: Asbestos Cement Pipe and Sheet (ACPS) DATE: 2012 DOC#: ACPS096 DOCUMENT DESCRIPTION: Journal Article - Asbestos Exposure among Mitering Workers - Case Reports SH W Safety and Health i Work ,, e-shaw.org pISSN: 2093-7911 elSSN. 2093-7997 Saf Health Work 2012;3:235-40 | http://dx.doi.Org/10.5491/SHAW.2012.3.3.235 Case Report Asbestos Exposure among Mitering Workers W antanee PHANPRASIT1, D usit SUJIRARAT1, P iru tch ad a MUSIGAPONG2, Penpatra SRIPAIBOONKIJ3 and Chalerm chai CHAIKITTIPORN1 fa c u lty of Public Health, Mahidol University , 2Suranaree University of Technology, Naxhon Ratchasima 3Faculty of Public Health, Thammasart University, Bangkok, Thailand The objectives are to compare the airborne asbestos concentrations resulted from mitering of abestos cement roof sheets by a high-speed motor and a hand saw, and to monitor whether other workers near the test sites are vulnerable to the- fibers exceed ing the occupational exposure limit. Four test cases were carried out and altogether 7 personal and 4 area air samples were col lected. The NIOSH method 7400 was employed for the air samplings and analysis. Using the phase contrast microscopy, fiber counting was conducted under Rule A. The study showed that the fiber concentration medians for personal air samples gathered from the two tools were 4.11 fibers/cc (ranged: 1.33-12.41 fibers/cc) and 0.13 fibers/cc (ranged: 0.01-5.00 fibers/cc) respectively. The median for the area samples was 0.59 fibers/cc (ranged: 0.14-3.32 fibers/cc). Comparing each study case, the concentration level caused by the high-speed motor saw was more than twice that of the hand saw. According to the area samples, the workers nearby the test site are at risk from high exposure to asbestos. Key Words: Asbestos, Cement sheets, Mitering, Construction, Exposure Introduction Due to its resulting health hazard [1-3], asbestos has been completely or partially prohibited in many countries. Asbestosbased products are used extensively in several countries because of its usefulness in providing, good insulation and resistance to acid, base, and heat. In addition, it is a good reinforcement for cement and resin. The use of asbestos is particularly common in Asia and Africa [4,5], The most commonly used asbestos products are friction and construction materials, such as asbes tos cement (AC) flat, corrugated sheets, and cement pipes. In some countries, asbestos corrugated-roof sheets are popular be- Received: September 21,2011, Revised: March 31,2012 Accepted: April 20,2012, Available online: August 30,2012 Correspondence to: Wantanee PHANPRASIT Department of Occupational Health and Safety, Mahidol University 420/1, Bangkok [10400], Thailand Tel: +66-2-644-4069, Fax: +66-2-354-8561 E-mail: phwpp@mahidol.ac.th cause they are cheap, durable and provide good heat insulation [ 6- 8] , Recent studies in four AC roof tile factories in Thailand [9] and one in India [10] indicated that the average fiber concentra tion levels in these two studies were relatively low at 0.078 (0 19) fibers/cc and 0.04-0.07 fibers/cc respectively, while the asbestos roof-tile removal generated 0.1-0.4 fibers/cc approximately [11], The low concentration levels can result in a low health-risk im pact on the population. Thus, these factors could be the reason for reported cases of asbestos illness in Thailand. One study [12] went as far as indicating negative results for the expected increases in the asbestos-related mortality. Low environmental exposure to asbestos was cited by these studies. As a result, supporters of asbestos use in Thailand have tried to convince authorities that AC roof sheets are of the non-friable asbestos containing material (ACM) type and that the quantity of asbes tos fibers generated from the products is very low In addition, supporters claimed that occupational exposure could be limited Copyright 2012 by Safety and Health at W ork (S H O W ) This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http //creativecommons org/licenses/by-nc/3 0/), which permit - unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited Phanprasit W et al. Safety and Health at Work ` Vol 5, No }, Sep ?0, 2012 easily by engineering-control measures and good practices in the workplace. However, some parts of the AC roof-tile life cycle were ignored, such as mitering and disposal. In Thailand's rural areas, as in other countries in Asia and Africa, people tend to build their own houses to save the labor cost and most often do the roof mitering work by themselves. This practice endangers their health, the health of their co workers, and the health of individuals adjacent to a high-level asbestos exposure. The pro-asbestos group, however, believes that the situation does not subject people to health risks from high doses of fiber exposure because the work is normally car ried out in the open areas, which dilute the dust concentration to the extent it may no longer cause any harm. This study aims to show that there are high-level concen trations of airborne asbestos fiber generated during roof-tile mitering by each type of the test tools, a high-speed motor saw with fiber blade and a hand saw. Case Report Corrugated roof sheets contain by weight approximately 10% to 15% of asbestos and are usually mitered by a high-speed motor saw and a metal-cuttmg or wood-cutting saw. Four cases were studied with each performed separately by a worker on different days in various ventilated, open-air locations. In Cases 1-3, the workers employed both types of equipment, while in Case 4, worker used only a high-speed motor saw. The workers were duly informed of the study's goals, procedures, risks, benefits and of their freedom of choice. They were encouraged to ask questions; those agreemg to participa tion were continued in the study. The workers were asked to perform mitering by both types of saw, and to cut at the speed and quantity of roof sheets as they would normally. The miter ing time was 15 minutes for each saw Both personal and area air samples were collected us ing the National Institute for Occupational Safety and Health (NIOSH) method 7400. The SKC Airchek model 224-PCXR4 personal pumps (SKC Inc., Pennsylvania, PA, USA) were used to draw air in at the flow rate of 2 L/minute, passing through the 25 mm cellulose ester membrane filter placed in a cassette equipped with an extension cowl. The pumps were calibrated by the bubble meter (primary standard set) before and after the collection of the samples. The average flow rates of pre- and post-calibration were used for the calculation of air sampling volume. A set of pump and sampler was attached to the worker for personal samplmg For the collection of area samples, the sampling instrument was set at approximately two to three meters away from the mitering pomt. The quantity of sheets cut simultaneously was recorded. During the test, workers' be haviors and environmental conditions of the surrounding areas were also observed. For Cases 1-3, the exercise began with a hand saw fol lowed by a high-speed motor saw. Each saw was used continu ously for 15 minutes, with a 30-minute break in between. A personal air sampling, which began immediately just before the mitering, was taken for each of the two aits, lasting about 30 minutes. An area samplmg was taken for the entire test for 60 minutes. Placed in a wooden box, the samples were car ried back to the laboratory and prepared for the counting by the phase contrast microscopy, equipped with Walton-Beckett Graticule type G-22 counting area of 0.00785 mm2. The sample analysis was in accordance with the N1OSH's counting Rule A, which sets the limit of detection at 7 fibers/mm2. Case 1 was conducted under the roof in a ventilated area (Fig. 1). Only one sheet at a time was cut using wood-cutting saw and two slowly being cut by a motor saw with the speed of 800 rpm. The worker was aware of the dust and positioned himself up-wind. Case 2 (Fig. 2) was conducted in a roof-shaded area and without any building nearby. The wind was stagnant for most of the time. Both the metal-cutting and high-speed motor (1,200 rpm) saws were used. One to 2 sheets were cut at a time by the metal-cutting saw and 4 to 5 by the latter. The worker per formed the task quickly and was conscious of putting himself at risk from dust exposure. Case 3 (Fig. 3) was tested in an outdoor area where the wind often changed direction. One or more was cut at the same time by a metal-cutting saw and then 3-4 by a high-speed motor (1,200 rpm) saw. Aware of the dust, the worker tried to protea Fig. 1. Hand saw mitering. e-shaw ong Asbestos Exposure among Mitering Workers Saf Health Work 2012,5 255-40 Fig. 3. Hand saw and motor saw mitering. himself by moving up-wind. The wind changed direction dra matically, and the worker was unable to escape the dust. Case 4 was conducted in a ventilated area situated be tween 2 buildings (Fig. 4). Using only a high-speed motor (1,200 rpm) saw, the worker slowly cut the roof-tile one at a time. The wind changed direction occasionally, but the worker's attempts to stay ahead of the wind were restricted by the site's space limitation. As shown in Table 1, the fiber concentration levels of all personal samples taken for 30 minutes from a high-speed motor saw exceeded the Occupational Safety and Health Administra tion of the United States (OSHA) 30 minutes excursion stan dard of 1 fibers/cc, with the median of 4.11 fibers/cc and the range in between 1.33-12.41 fibers/cc. During the tests using Fig. 4. Motor saw mitering. vv.\., e-shaw org Phanprasit W et al Safety and Health at Work : Vol J, No J, Sep JO, 2012 Table 1. Fiber concentrations obtaining from personal and area samples taken during the mitering Equipment (1) High speed motor saw Variables Type of sample Fiber concentration (fibers/cc) Personal Fiber density (fibers/mm2) Case 1 1.70 265.0 Case 2 12.41 1,745.2 Case 3 6.52 1,015.9 Number of sample 1 1 1 Number of sheet cut 2 4-5 3-4 Speed of tool (rpm) 800 1,200 1,200 (2) Hand saw Fiber concentration (fibers/cc) Personal 0.01* 5.00 0.13 Fiber density (fibers/mm2) Number of sample 1.3 780.3 20.4 1 1 1 Number of sheet cut 1 1-2 1-2 (1) + (2) Fiber concentration (fibers/cc) Area Fiber density (fibers/mm2) 0.44 135.7 3.32 1,035.0 0.74 231.4 *Lower than the limit of detection. Case 4 1.33 207.7 1 1 1,200 0.14 21.0 ; ; Median 411 0.13 0.59 hand saws, only one sample, taken from the Case 2, was over the excursion standard, showing the median of 0.13 fibers/cc and the range of 0.01-5.00 fibers/cc. All area samples from the 2 cutting tools showed the median of 0.59 fibers/cc with the range of 0.14-3.32 fibers/cc. Discussion Asbestos can last a long time m the lungs. The OSHA excur sion limit has been adopted to help protect workers from expos ing themselves, however briefly, from high doses of the harmful fibers. At construction sites, roof-tile cuttings are usually carried out all day long and for big projects can contmue for many days and even months. Since the data was collected from a brief, time-limited exercise, the results were compared with the OSHA's excursion limit. Had the test been carried out for eight hours continuously, for example, the fiber concentration levels from the use of a high-speed motor saw could be as high as 4.11 fibers/cc and 0.59 fibers/cc for personal and area samples re spectively, far exceeding the time-weighted average standard of 0 1 fibers/cc. As such, the workers and others working nearby would be subjected to the asbestos exposure levels higher than those set by the OSHA limit. The study shows that the number of sheets cut simultane ously has greater influence on the asbestos fiber-concentration levels than the speed of the saws. More sheets cut together at the same time cause invariably more concentrations. In Case 1, the 800 rpm motor saw, cutting 2 sheets at the same time, gen erated 1.70 fibers/cc, a level higher than that produced by Case 4, at 1.33 fibers/cc, cutting just only one sheet at the faster 1,200 rpm speed. The workers' behaviors and practices had an adverse effect on the exposure problem. Among the 4 cases, Case 2 's worker faced the greatest exposure risk from working rapidly and from positioning himself closer to the task (Fig. 2) In Cases 3 and 4, each worker tried to minimize the impact by staying up wind during the cuttings, which were performed at a normal speed. To avoid the dust, Case 4 's worker performed the cutting slowly. In all locations of the study, the environmental conditions and the surroundings' ventilation were good; the speed of air flow at each test site varied. In Case 2, the air movement was stagnant, but was stronger in Cases 3 and 4. Some turbulence was recorded in Case 3. These varied conditions had differen tial impacts on the asbestos concentration levels, regardless of the saws used and sheet quantity factors. The Case 2 sample showed the highest concentration level. We can conclude from the study that the environmental conditions, the number of sheets cut simultaneously, the work ers' behaviors and the choice of equipment have significant influences on the airborne asbestos concentration levels. Since the mitering duration at construction sites usually lasts much longer than those of the tests, and there is no threshold for as bestos as a cancer causing agent; mitering increases chances of lung cancer not only among construction workers, but also the public at large. Many studies on occupational lung cancer on construc tion workers blame asbestos as one of the leading causes of / e-shaw org Asbestos Exposure among Mitering Workeis Saf Health Work 2012;3 2 -40 the workers' disease [13,14]. There is a counter-argument that construction materials used in Europe, the United States, and other cold-weathered regions are of the friable ACM type, which is claimed to generate more asbestos concentrations than the non-friable substances, such as the AC sheets that are used extensively in Thailand and in other Asian countries. Accord ing to the argument, the AC sheets are safe to use for workers and others living nearby. This study shows that the argument is invalid. The AC sheets release asbestos dust at concentrations harmful not only to the workers, but also to the general public as well. According to a survey of cancer patients in Thailand, lung cancer was most common among men between 2001-2009 (in cidence rates) [15]. A Thai public health study found the coun try's northern region to have the highest lung cancer incidence rate during 1998-2000. Another study blamed radon [16], air pollutions and home-made cigarettes for age-standardized inci dence rate (ASR, 30.7) [17], However, asbestos exposure from the roof-tile mitering is not considered as a contributing cause of lung cancer among Thais. However in Thailand, corrugated AC roof sheets have been used extensively for sometime. So far, international efforts to prohibit the use of asbestos have been inadequate and less powerful. The first attempt was made in 1999 by the Collegium Ramazzini, an international academic society specializing in environmental and occupa tional medicines, which issued a 3-fold rationale calling for the ban of asbestos on the premises [18,19]: "safer substitute ma terials are readily available, `controlled' use of asbestos is not possible, and the health risks of asbestos are not acceptable in either the industrialized or the newly industrializing nations." Later, the International Labor Organization has launched sev eral campaigns continuously on asbestos ban. Nevertheless, the use of asbestos has been halted in 44 countries in 2009 [20], and the number increased to 55 in the following year [21], In Thailand, efforts to restrict the use of asbestos have yet to be successful. False beliefs that effective environment-control measure and its relatively low costs are largely responsible for the lack of progress in limiting its use. Even if factories manage to have an effective workers' exposure control as some have claimed, the exposure problem, as illustrated by this study, does not confine asbestos to the workplace alone. In addition, the asbestos containing materials including AC roof tile wastes disposal have not yet been controlled. Failure to impose the restrictive use of asbestos products would not be beneficial to the public. Lately, nevertheless, some preventive measures have been adopted. To promote the public health risk awareness, the Office of the Consumers Protection Board in 2010 issued a regulation requiring mandatory affixing of warning labels on all asbestos-containmg products In 2011, the government approved a strategic plan calling for a ban on chrysotile, includ ing cement sheets. However, it did not set a time frame for the plan's adoption. As long as people have easy access to asbestos and benefit from its low cost, it will continue to be used extensively. But, the question is: would it be beneficial to the public as a whole if the people's health is put in jeopardy? There are available many asbestos-free and other substitute products, though at initially higher costs. The manufacturers should be made aware of their social responsibility and encouraged to replace asbestos with health-safe substitute materials. To ensure their well-being, con sumers would certainly prefer safer products. In the long run, greater demand will encourage greater production, resulting in greater supply and eventually to lowering production costs. The government can be instrumental in facilitating the massmarket production of asbestos-substitute goods by adopting long awaited national policies and strategic plans. Conflict of Interest No potential conflict of interest relevant to this article was re ported. Acknowledgments This study was part of the work supported by the Roofing and Accessories Industry Club. 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