Document zrN4dQbOyaYyDwz5eGejmrmn

FILE NAME Dental Asbestos DEN DATE 2017 Feb DOC DEN007 DOCUMENT DESCRIPTION Journal Article - American Journal of Industrial Medicine - Malignant Mesothelioma Due to Asbestos Exposure in Dental Tape AMERICAN JOURNAL OF INDUSTRIAL MEDICINE Malignant Mesothelioma Due to Asbestos Exposure in Dental Tape Steven B. Markowitz MD DrPH1 and Jacqueline M. Moline MD M.Sc Although most cases of malignant mesothelioma of the pleura are caused by one or more readily recognized sources of exposure to asbestos cases of the disease with more occult exposure occur especially since asbestos has been used in over 3,000 products Dental lining tape contained asbestos from the 1930s until at least the 1970s and was used in the lost wax method ofcasting crowns bridges and other metal dental prosthetic devices We report six cases of pathology malignant mesothelioma mostly among dentists following exposure to airborne dust from asbestos dental tape which resulted in asbestos tort litigation According to evidence available at present chrysotile asbestos was the type of asbestos used in dental tape in the past in the United States and the described cases followed relatively brief and intermittent exposure to this type of asbestos These cases underscore the need for comprehensive exposure histories to determine exposure scenarios Am J. Ind Med '2017 Wiley Periodicals Inc. KEY WORDS mesothelioma dental tape chrysotile asbestos dentist INTRODUCTION Given that the vast majority of cases of malignant mesothelioma of the pleura are caused by one or more specified sources of exposure to asbestos Leigh and Driscoll 2003 Marinaccio et al 2010 Lacourt et al 2014 it is both feasible for and incumbent upon health care providers to identify these sources Many of the principal sources of asbestos exposure are known and readily recognized cement sealing materials textiles brakes and others However asbestos was used in over 3,000 products in the past so that cases of malignant mesothelioma are likely to occur following less common uses of asbestos which may elude the clinician taking a history It is nonetheless important to alert clinicians to these sources both to enhance decision in Queens College City University of New York Queens New York Northwell Health and Hofstra Northwell School of Medicine New York New York * Correspondence to SB Markowitz MD DrPH Queens Remsen Hall 65- 30 Kissena Blvd Queens NY 11367 mail steven markowigtcz cuny edu Accepted 13 January 2017 DOI 10 1002 22696 Published online in Wiley Online Library wileyonlinelibrary.com wileyonlinelibrary.com diagnosis and screening for asbestos diseases and to communicate the breadth of the continuing asbestos disease epidemic Beginning in the 1930s asbestos was used in dentistry as a liner during fabrication of crowns and other metal prostheses Sichletidis et al 2009 To our knowledge there is a single published case report in the English language ofa mesothelioma in a dentist Reid et al 1991 We present six cases of individuals with malignant mesothelioma who were exposed to asbestos in the 1960s to the 1970s while using containing dental tape to fabricate dental crowns and bridges or in one case using dental lining tape to cast jewelry All six were diagnosed with malignant mesothelioma and all died from the disease The cases were referred to the authors SM and JM for medico evaluation as part of tort litigation All information was obtained from medical records and legal depositions of the cases and in one case also a brother who was a dentist In every case a pathology report confirmed the diagnosis of malignant mesothelioma Informed consent and Institutional Review Board review were not obtained in these cases because deceased individuals are not considered human research subjects subject to Institutional Review Board review '2017 Wiley Periodicals Inc. 2 Markowitz and Moline CASE PRESENTATIONS Case 1 TU was a year dentist with a history of hypertension hyperlipidemia and gout when he developed severe coughing episodes and syncope in April 2014. A chest ray showed a large left pleural effusion and a chest CT scan showed near complete opacification of the left chest Numerous areas of calcified pleura were seen in the lower posterior left chest Repeat thoracenteses showed atypical mesothelial cells and a PET scan demonstrated numerous areas of increased uptake in the left chest TU underwent left assisted thoracoscopic surgery and parietal pleurectomy in late May 2014. The surgeon noted the presence of scattered pleural plaques consistent with some prior asbestos exposure Pathology review including immunohistochemical stains confirmed the presence of a malignant mesothelioma of the pleura TU received six cycles of pemetrexed and cisplatin chemotherapy and subsequently participated in a clinical vaccine trial followed by additional chemotherapy His health deteriorated and he died from malignant mesothelioma in October 2015 TU attended dental school in the United States between 1970 and 1974. He fabricated crowns and bridges using the lost wax method of casting He recalled making 114 units during dental school He described that he tore the dental tape by hand which he associated with producing some dust and placed it in the casting crucible After heating he scraped out the lining material creating airborne dust He later swept up the debris that landed on his work table by hand After dental school TU worked in a dental practice where he continued to make dental prostheses using the same lost wax method and dental tape though less frequently TU's only other potential exposure to asbestos was when he applied and sanded some joint compound in a limited renovation of his own home in 1976-1977 Case 2 In September 2004 a year dentist FX presented to a physician with dyspnea fever chest discomfort cough and wheezing He had a history of a retroperitoneal liposarcoma which was successfully resected in 2001. A chest ray in September 2004 showed a large right pleural effusion and FX underwent thoracentesis at the local Emergency Department cytology review indicated no evidence of malignant cells A chest CT showed a likely pleural mass FX's symptoms worsened and he had a PET scan bronchoscopy and thoracoscopy with talc pleurodesis Thoracoscopic biopsy was positive for malignant mesothelioma of the right pleura biphasic type In late September FX started combination chemotherapy with pemetrexed and cisplatin In November 2004 he underwent an extrapleural pneumonectomy followed by adjuvant radiation in late December 2004. His condition worsened during the ensuing months and FX died from malignant mesothelioma of the pleura in June 2005 FX's was a lifelong practicing dentist He attended dental school from 1971 to 1975 where he produced approximately 100 crowns using the lost wax technique employing containing tape as the lining material He ripped or cut the dental tape and discarded the debris from the casting work He reported that this work was dusty from his own and also from other student use of dental tape After graduating from dental school he no longer performed crown fabrication and had no other known asbestos exposure Case 3 TZ was a 55 year practicing healthy dentist who developed fatigue fever and chills in the spring of 2003. Past medical history was notable for hypertension and benign prostatic hypertrophy Due to significant nocturia an abdominal CT scan was performed in June 2003 showing an abnormality of the left inferior pleura A chest CT was significant for extensive pleural thickening along the medial pleural surface of the left chest He underwent a thoracotomy which revealed a soft necrotic pleural tumor and pathology review of biopsy material demonstrated a malignant mesothelioma of the pleura epithelial and anaplastic type with pleomorphic giant cells TZ underwent a left extrapleural pneumonectomy in July 2003. He then received radiation treatment and chemotherapy initially with gemcitabine and carboplatin and subsequently with pemetrexed and carboplatin He developed atrial flutter depression anxiety and significant chest pain TZ died from malignant mesothelioma of the pleura in May 2004 at the age of 56 TZ attended the same dental school as Case 2 from 1969 to 1973 and produced multiple crowns using asbestoscontaining tape for lining the casting rings during the second half of dental school TZ recalled that both ripping the liner and using a hammer to break the crown out of the hardened investment material generated visible dust He reported that the work laboratory was dusty from his work and that of his classmates and he had to clean up the dust with a handheld broom At one point in school he did this work on a daily basis for 2 months After graduating from dental school he reported no further asbestos exposure Case 4 BT was a year dentist who developed a fever weight loss and fatigue in 2003. A CT scan of the chest Mesothelioma Due to Asbestos in Dental Tape 3 showed a suspicious right upper lung mass A directed biopsy of the chest mass was on pathology review positive for malignant mesothelioma biphasic type which was confirmed by results of immunohistochemical staining In September 2003 BT underwent radical extrapleural pneumonectomy resection and construction of the right side of the pericardium and the right diaphragm Tumor nodules were seen on the visceral and parietal pleura and the right diaphragm The surgeon commented in the operative report on an apparent benign pleural plaque which was seen but not removed Pathology review of obtained tissue confirmed the presence of malignant mesothelioma in the pleura diaphragm pericardium and lung parenchyma He did poorly in the months following surgery and died of malignant mesothelioma of the pleura in January 2004 BT attended dental school in the United States between 1964 and 1969. Beginning in his first year BT used asbestoscontaining dental tape in making crowns inlays and bridge castings This involved tearing asbestos tape pressing the tape in the process of making the mold and removing and discarding the tape after casting Pictures of the laboratory of the dental school in 1966 confirmed that dozens of students were working with dental lining tape within a few feet of each other at laboratory benches BT also used asbestos tape in doing dental laboratory work in a laboratory at a dental fraternity house He had no subsequent exposure to asbestoscontaining products Case 5 In June 2006 69 year UM developed sided chest pressure dyspnea on exertion and weight loss He had a chest ray in November 2006 which showed a right pleural effusion and an accompanying infiltrate Chest CT scan on the following day showed a right pleural effusion with multiple pleural nodules in the right upper chest atelectasis and pleural thickening In December 2006 results of a thoracentesis suggested a possible malignancy UM then underwent a thoracotomy but the entire tumor could not be removed due to invasion of the chest wall Pathology review of surgical tissue confirmed the diagnosis of malignant mesothelioma of the pleura In late January 2007 he began treatment with pemetrexed and cisplatin for six cycles and received radiation therapy which was completed in August 2007. UM died in May 2010 From 1967 to 1973 UM attended dental technician school and used asbestos tape to line casting rings during crown and bridge production He used scissors or an Exacto knife to cut the asbestos tape which was supplied in boxes that contained dust He used containing gloves to remove casting rings from the ovens He had daily exposure to asbestos in the laboratory setting during his years at dental technician school There were approximately 75-100 other technicians in the laboratory room He recalls sweeping his work area which he described as being dusty UM had other possible sources of exposure to asbestos UM's father worked in shipyards for approximately 5 years in the 1940s In high school chemistry laboratory UM recalled potential exposure to asbestos sheets on the tripods of Bunsen burners Case 6 HK was a year woman with a history of hysterectomy and oopherectomy who was hospitalized for small bowel obstruction in August 2005. A CT scan of the abdomen showed omental caking Core needle biopsy of the tumor underwent pathology review with the diagnosis of malignant mesothelioma of the peritoneum epithelial type as confirmed by results of immunohistohemical staining She sought treatment at a university hospital where pathology review confirmed the mesothelioma She received chemotherapy with cisplatin and pemetrexed and subsequently underwent laparatomy debulking of tumor omentectomy and small bowel resection in October 2005. Pathology review of tissue obtained at surgery again supported the diagnosis of malignant mesothelioma of the peritoneum HK received chemotherapy during the 7 months following surgery but suffered progression of the mesothelioma and died in November 2006 HK was a silversmith She had received undergraduate and graduate degrees in art in 1978 and 1981. For 1 year in college she cast jewelry using the lost wax method of casting lining the sides of the crucible with asbestos dental tape prior to casting After casting she scraped out the asbestos tape creating airborne dust She also used this asbestos tape to line a surface on which to solder jewelry and she reported that the tape deteriorated and became dusty after repeated use She swept with a dry broom in the art classroom where casts were fabricated HK additionally used asbestos boards on which she soldered as a student and recalled that these boards eventually broke after repeated use HK did not subsequently use containing materials as an artist or have any other exposure to asbestos after receiving her academic degrees DISCUSSION Malignant mesothelioma the signal cancer of asbestos exposure is known to occur following limited exposure to asbestos Or as succinctly expressed in a consensus report on attribution of asbestos diseases two decades ago an occupational history of brief or level exposure should be considered sufficient for mesothelioma to be designated as occupationally related Helsinki 1997 Numerous epidemiological studies have provided quantitative estimates of 4 Markowitz and Moline the increased risk of malignant mesothelioma in relation to relatively modest occupational and occupational exposures to asbestos Iwatsubo et al 1998 Agudo et al 2000 Magnani et al 2000 Rodelsperger et al 2001 Lacourt et al 2014 Markowitz 2015 The exposure to containing dental tape described in these case reports was episodic limited in degree and in most of the cases occurred over a few years only In all six cases reported herein dental lining tape was their exclusive four cases or primary two cases source of exposure to asbestos Each case personally described use of the dental tape that created visible airborne dust and worked in proximity to other students who were performing similar work adding to the asbestos exposure of the index cases Latency between onset of exposure to asbestos and diagnosis of mesothelioma was typical ranging from 28 to 44 years Asbestos was used in dental lining tape from the 1930s until at least the 1970s The dental lining tape was used to cast metal dental prostheses and contained chrysotile asbestos in the United States Cutright et al 1980 Davis 1987 In the early 20th century dentistry began to employ the lost wax method of casting dental prostheses This method involves making a positive reproduction of the desired object in wax placing it in a ring or crucible and then surrounding the wax object with refractory or investment material The inner surface of the crucible or ring was lined with asbestos lining tape prior to casting at a high temperature Metal is injected into the mold and replaces the wax After casting and cooling the crucible is opened the lining and refractory material chipped or scraped off and the desired object recovered Jewelry production subsequently adopted this method of producing rings and other items Only one case of malignant mesothelioma attributable to dental materials containing asbestos has been reported in the English language published literature Reid et al 1991 Reid et al 1991 reported a year dentist with malignant mesothelioma of the pleura whose lung tissue showed 0.7 ^ 10 crocidolite fibers per gram dry lung which was elevated compared to the general population No other source of asbestos exposure was identified Sichletidis et al 2009 reported finding typical asbestos calcified pleural plaques among three lifelong dentists who had previously used asbestoscontaining dental tape to cast dental prosthetic devices Prior studies of chronic respiratory disease and cancer among dental personnel are complicated by multiple exposures including silica beryllium and chromium Choudat et 1993 Radi et 2002 Notably Radi et al 2002 studied 134 dental technicians and 131 exposed controls and found an association between report of prior exposure to asbestos and the presence of radiographic small lung opacities with profusion 1/0 Choudat et al 1993 found predominantly small linear irregular opacities s or t according to the ILO scale on chest films of dental technicians which increased in prevalence with increasing duration of employment as a dental technician Nayebzadeh et al 1999 examined lung tissue of a dental technician with silicosis and hard metal pneumoco- niosis Transmission electron microscopy and energy dispersive spectrometry analysis of lung biopsy material showed 12,600 chrysotile fibers < per mg dry lung and 5,440 chrysotile fibers > per mg dry lung which was 1.5 to two times higher than the pulmonary chrysotile fiber burden found among Quebec miners and millers and 24 3t2imes higher than that of the reference population No other types of asbestos fibers were described The authors concluded that the measured concentration of asbestos fibers was indicative of occupational exposure to asbestos and given the absence of any history of asbestos exposure in work other than dental work the patient's asbestos fiber burden was due to his work in the dental laboratory Nayebzadeh et al 1999 Mortality studies of dentists conducted over the past several decades do not report deaths from malignant mesothelioma Eriksson et al 1998 Shimpo et al 1998 Simning and van Wijngaarden 2007 Koifman et al 2014 However studies that relied on ICD coding prior to 1998 when ICD was adopted did not have a code specific for malignant mesothelioma to use In addition a relatively low but nonetheless elevated risk of malignant mesothelioma would be difficult to detect unless the study included a large number of deaths Finally if use of containing dental tape was highest in the 1960s and 1970s the resultant cases of malignant mesothelioma would not be expected until 2000 or after and would not have been recorded in studies to date which describe mortality patterns prior to 2000 There has been little published research assessing asbestos exposure in dental casting operations Brune and Beltesbrekke 1981 used light microscopy to measure airborne asbestos fiber concentrations during dismantling of a finished mold in a dental workroom In short air samples they found levels 21 21 and 27 asbestos fibers at 12 inches from the mold at the time of dismantling Levels declined to 2 fibers after 10 min following dismantling Brune and Beltesbrekke 1981 Davis used phase contrast microscopy to measure airborne asbestos fiber concentrations in three samples over 30 min periods following tearing placement and removal of dental tape and found breathing zone concentrations of 0.065-0.092 fibers Davis 1995 Sichletidis simulated the dental casting operation in 2009 and found 0.008 chrysotile asbestos fibers during a single 4 hr sampling period using phase contrast microscopy Sichletidis et al 2009 Notably according to evidence available at present dental tape used in the United States contained chrysotile fiber Mesothelioma Due to Asbestos in Dental Tape 5 rather than the commercial amphiboles Cutright et al , 1980 Davis 1987 The duration frequency and likely intensity of asbestos exposure for the cases reported herein indicated a likely modest cumulative exposure to chrysotile but no exposure to the commercial amphibole varieties of asbestos except for the possible presence of a small amount of tremolite in commercially used chrysotile These findings add to current evidence that exposure to chrysotile asbestos at relatively low exposure levels can cause malignant mesothelioma In the setting of a known causal link between an exposure and disease especially one with as close a link as exists between asbestos and malignant mesothelioma a case series can establish that a particular set of asbestos exposure conditions can cause malignant mesothelioma Checkoway et al 2004 Given the absence or near absence of alternative exposures to asbestos the finding of the characteristic latency period between onset of asbestos exposure and diagnosis of malignant mesothelioma and pathologic confirmation of disease the conclusion that the dentists and jeweler reported herein developed malignant mesothelioma is justified Moreover the cases described herein used the containing dental tape in different schools and different exposure settings providing evidence that the exposure to asbestos through manipulation of dental tape was fairly robust Sporadic cases of malignant mesothelioma in other atypical occupations are likely to occur in the foreseeable future and may be readily detected by taking a thorough occupational history AUTHORS CONTRIBUTIONS SM and JM participated in the following a conception or design of the work b the acquisition analysis or interpretation of data c drafting the work and revising it critically for important intellectual content d final approval of the version to be published and e agreement to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved ACKNOWLEDGMENT Thanks to Lauren Zajac MD MPH who assisted in finding relevant literature and abstracting some information for the report FUNDING The conception design interpretation writing and decision to publish this report received no funding ETHICS APPROVAL AND INFORMED CONSENT Informed consent and Institutional Review Board review were not obtained in these cases because deceased individuals are not consider human research subjects subject to Institutional Review Board review DISCLOSURE AUTHORS The authors have served as expert witnesses in cases involving asbestos tort litigation DISCLOSURE BY AJIM EDITOR OF RECORD Rodney Ehrlich declares that he has no conflicts of interest in the review and publication decision regarding this article DISCLAIMER None REFERENCES Agudo A Gonzalez CA Bleda MJ Ram^>rezJ Hern^ndezS L^pezF. 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