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FILE NAME Dental Asbestos DEN DATE 1977 DOC DEN103 DOCUMENT DESCRIPTION US Army Research Report - Asbestos A Subtle Carcinogen in the Dental Lab A045 027 UNCLASSIUNCLASFIFIED IUNCLEASSIDFIED ARMY INST ASBESTOS SEP 77 DE OF DENTAL RESEARCH WASHINGTON DC DC A SUBTLE CARCINOGEN IN THE DENTAL DE CUTRIGHT EF EF HUGET JM JM BRADY LABORATORY SEM G 6/5 AND --ETC SERRE EER) 09778 11..00 | 20 18 .25 1.4 1.6 09778 SECURITY SECURITY CLASSIFICATION CLASSIFICATION OF THIS PAGE When Data Entered REPORT DOCUMENTATION PAGE 1. REPORT NUMBER 2. GOVT AC SSION . READ INSTRUCTIONS ORE COMPLETING FORM IENT'S CATALOG NUMBER 4. TEE and Subtitle ; _ Asbestos A Subtle Carcinogen in the Dental Laboratory SEM and Microprobe Study ; ae es rn Be Ne DE./Cutright N . gene 3 EF./Huget EF./Huget EF./Huget and JoM./ Brady 5. . 5. TYPE OF REPORT & PERIOD COVERED COVERED ee PERIOD for Manuscript= | Jul Sept 77 NUMBER 8. CONTRACT OR GRANT NUMBER 9. PERFORMING ORGANIZATION NAME AND ADDRESS US Army Institute of Dental Research Vv Walter Reed Army Medical Center 11. CONTROLLING OFFICE NAME AND ADDRESS US Army Medical Research & Development Command || 7 EQDA SGRD Washington 14. MONITORING AGENCY NAME & ADDRESS different from Controlling Office September 77 UNCLASSIFIED 15. DECLASSIFICATION DECLASSIFICATIONDECLASIFICATION SCHEDULE DODOWW NGRADING NGRADING 16. DISTRIBUTION STATEMENT of this Report This document has been approved is unlimited for public release and sale its distribution 17. DISTRIBUTION DISTRIBUTION STATEMENT of the abstract entereidn Block 20 if different from Report 18. SUPPLEMENTARY NOTES D . cate 11 1977 {\ txt WES C 19. KEY WORDS Continue on side if and necessary identity by block number Asbestos chyrsotile carcinogen S.E.M. microprobe dental hazard i == == and by block 20. ABSTRACT Continue containing side if necessary Identify Particles of debris emanating an asbestos containing dental laboratory material were characterized with the scanning electron microscope and ray microprobe The dimensions and com- position of these particles suggest their potential to behave as subtle carcino- gens With almost daily use of dust producing asbestos in the dental laboratory improper handling of this substance could be hazardous to the health of den- personnel It is recommended that high standards of personal and laboratory be employed in the handling of asbestos :( 09778 yee ASBESTOS A SUBTLE CARCINOGEN IN THE DENTAL LABORATORY SEM AND MICROPROBE STUDY Duane E. Cutright D.D.S. Ph.D. Eugene F. Huget D.D.S. M.S ** John M. Brady D.D.S. M.S *** U.S. Army Institute of Dental Research Walter Reed Army Medical Center Washington D.C. 20012 Commercial materials and equipment are identified in this report to specify the investigative procedure Such identification does not imply recommendation or endorsement or that the materials and equipment are necessarily the best available for the purpose * ** *** Commander U.S. Army Institute of Dental Research Chief Division of Dental Materials Chief Department of Biophysics 09778 Risks encountered in dental practice have become foci of a number of studies Dangers associated with the inhalation of particulate matter bac- teria viruses enamel dentin calculus and amalgam from microbial aerosols 1,2 produced during the use of speed rotary instruments have been addressed Also investigations have been conducted to establish and to define acceptable limits for operating room levels of mercury vapor and of nitrous oxide 6-8 Recently concern has been shown for asbestos fibers which emanate from the powder component of some periodontal dressings as well as from liners for casting rings and crucibles 9-10 The present study was conducted to sample and to characterize particulate debris encountered in the use of asbestos in the dental laboratory MATERIAL AND METHODS A. A three segment of inch wide ring liner was torn from a roll of asbestos by each of two laboratory workers Particulate matter re- maining on the thumbs and index fingers of the test subjects was removed with the use of acetate tape Additionally the sites from which debris had been removed were resampled after the workers washed and dried their hands Two three strips of the asbestos were heated in a burnout furnace at 1,300 for 45 minutes The strips were cooled to room temperature in open air and torn by two volunteers Sampling of particulate matter from the thumbs and index fingers of these individuals was accomplished as de- scribed above ~~ B. Samples of debris were collected on acetate tape from a bench top upon which 20 phosphate investment molds had been broken from asbestos- lined metal casting rings Additional particles were removed from a wall * Material supplied with Ceramigold Investment Whip Corp. Louisville KY 40217 09778 against which the bench was located from the muffle of a furnace from a casting machine and from a drawer in which a roll of liner had been stored The sampling tapes were sealed to aluminum stubs The debris taining side of each tape was coated with gold and palladium or carbon and examined with the use of a scanning electron microscope Photomicrographs of the collected matter were analyzed for determination of shape size and distribution of particulate components Elemental constituents of selected carbon coated particles were determined by dispersive ray microanalysis# RESULTS A. Material collected from thumbs and index fingers Scanning elec- tron microscopic examination showed aggregates of relatively straight parallel fibers and single randomly dispersed fibers Figure 1 The fibers though fragmented did not exhibit axial cleavage Diameters of the linear particles ranged from 0.10 to 1.0 ...m Generally fiber length exceeded 200 um. Morphological differences between the particles broken from unheated and heated strips of the test material were not detected Dispersive ray analysis of selected particles revealed that magnesium and silicon were the predominant constituents of the test material However small amounts of iron were also detected as well as sulfur and calcium Figure 2 Approximate elemental composition of the fiber was as follows magnesium 45 silicon 40 sulfur % calcium % and iron % Heating at a conventional mold burnout temperature did not alter the elemental composition of the woven fibers + Scanning Electron Microscope model 1000 Advanced Metals Research Corporation Burlington MA 01803 # Energy Dispersive Ray Analyzer model 707A with EDIT II Software EDAX International Prairie View IL 60069 09778 Fibers were not detected in the particulate matter removed from the digits of washed hands Occasional small spheroidal and plate particles found in one sample exhibited a broad range titanium silicon chlorine potassium calcium and iron of elemental constituents B. Material collected from laboratory bench storage drawer wall furnace and casting machine Samples of debris removed from the laboratory bench and wall contained fragmented slender particles Figure 3 Particles of similar configuration were recovered from the casting machine and from the storage drawer Analysis revealed that these filamentous particles were composed of magnesium silicon sulfur calcium and iron in the same relative concentration as found on the finger tips Particles detected within the muffle of the furnace were not fibrous ration of length to diameter less than 3 to 1 Constituents of these particles included silicon phosphorous calcium and sulfur DISCUSSION Asbestos is a term used to identify any one of several minerals which can be cruis ntohfe ibed rs However a particular mineral substance known as chrysolite is the principle source of commercial asbestos Chrysolite is a hydrated silicate of magnesium the approximate composition of which is em. 37 to 44 percent silicon dioxide 39 to 44 percent magnesoixuidme 12 to 15 Set percent water and 1 to 6 percent iron oxide Analytical data suggest that the AR fibrous material examined in this study is chrysolite Compositional features POG of the nonfibrous particles removed from the fingers of washed hands and from the furnace muffle infer the presence of debris from refractory investment materials The occupational risk associated with asbestos exposure has been well documented 12-16 In man exposure to asbestos dust is associated with an in- 3 09778 creased incidence of tumors of the lung and with pleural and peritoneal mesothelioma Asbestos fibers are subtle carcinogens that do not produce an obvious exposure relationship Usually a long latency precedes the onset of fibrogenic or carcinogenic activity and the effects of repeated exposures over long periods of time are cumulativ1e9 The threshold limit value TLV below which asbestos would not affect adversely the health of man is not known The current eight time weighted TLV for asbestos is 2 fibers per cubic centimeter of air however this limit has not been evaluated with regard to its effectiveness in the prevention of asbestos disease Additionally the mechanisms by which fibrous materials produce malignant disease are uncertain It has been shown however that the degree of carcinogenicity is related to fiber size rather than to composition.21 composition.21 Data from animal experiments have indicated that durable fibers less than 3 ...min diameter and more than 20 ...min length present the greatest hazard and the fibers described in this report fall within this range of size Since it has been shown that cigarette smoking increases the risk of lung cancer in asbestos workers it should be discouraged especially within the working area 22 The actual risk incurred in the use of dust producing asbestos in dental laboratories is unknown However the potential for inhalation or ingestion of asbestos particles by dental laboratory workers would appear to be greater than that of members of the general population Figure 4 The need for rigorous standards of personal and laboratory hygiene in the handling of asbestos is obvious Hand washing for example as shown in this study effectively removes the material from fingertips In view of these results reported here and in conformity with correct occupational health practices the following protective measures are suggested in dental clinics 4 09778 1. Inform all office and laboratory personnel of the potential danger of asbestos 2. Confine the storage and use of asbestos to a small area of the laboratory or to a small isolated working chamber 3. Isolate operatories and other offices from the dental laboratory 4. Insure the wearing of face masks and surgical gloves when asbestos or containing debris is handled 5. Encourage cutting in lieu of tearing of asbestos 6. Prevent smoking and eating in the dental laboratory 7. Prevent the transmission of asbestos waste by sewage lines and air exhaust systems to preclude its discharge within the community environment SUMMARY Particles of debris emanating from an asbestos containing dental labora- tory material were characterized with the scanning electron microscope and ray microprobe The dimensions and composition of these particles suggest their potential to behave as subtle carcinogens With almost daily use of dust producing asbestos in the dental laboratory the improper handling of this substance could be hazardous to the health of dental personnel It is recommethnatdheigdh standards of personal and laboratory hygiene be employed in the handling of asbestos | | 09778 REFERENCES 1. Travaglini E.A Larato D.C and Martin A. Dissemination of organism droplets by speed dental drills J Prosthet Dent 132 Feb 1966 2 Micik R.E Miller R.L Mazzarella M.A and Ryge G. dental procedures J Dent Res 48:49 Feb 1969 Studies on 3. Battistone G.C Hefferren J.J Miller R.A and Cutright D.E. Mercury its relation to the dentist's health and dental practice charac- teristics JADA 1182 Jun 1976 4 Mantyla D.G. and Wright O.D. Mercury toxicity in the dental office a neglected problem JADA 1189 Jun 1976 5. Eames W.B Gaspar J.D and Mohler H.C. The mercury enigma in dentistry JADA 1199 Jun 1976 6. Linde H.W and Bruce D.L. Occupational exposure of anesthetists to halothane nitrous oxide and radiation Anesthesiology 363 Apr 1969 7 Johnson E.G. Harmful pollution by anesthetic gases Lancet 824 Oct 1972 8 Nikki P. Are anesthetic gases harmful to operating room staff Ann Oe Clin Res 247 Oct 1972 oy 9. Burnett G. Substitute for asbestos in casting rings Br Dent J 141 Sept 1976 10. Council on Dental Therapeutics and Council on Dental Materials and Devices Hazards of asbestos in dentistry JADA 777 Apr 1976 09778 11. Berg D. Inorganic insulating materials In Standard Handbook for Electrical Engineers ed 10. New York McGray Book Co. 1968 p 355 12. Enterline P.E. Type of asbestos and respiratory cancer in the asbestos industry Arch Environ Health 312 Nov 1973 13. Selikoff I.J.1 and Nicholson W.J. Asbestos air pollution Arch Environ Health 25 Jul 1972 14. Weill H. and others Radiographic and physiologic patterns among workers engaged in manufacture of asbestos cement products J Occupational Med 248 Mar 1973 15. Doll R. Mortality from lung cancer in asbestos workers Br J Industr Med 12:81 Apr 1955 16. Cordova J.F Tesluk .; and Knudtson K.P. Asbestosis and carcinoma of the lung Cancer 1181 Dec 1962 17. Huper W.C. Occupational and nonoccupational exposure to asbestos Ann NY Acad Sci 184 Dec 1965 18. Stanton M.F and Wrench C. Mechanisms of mesothelioma induction with asbestos and fibrous glass J Natl Cancer Inst 797 Mar 1972 19. Thomson J.C. Asbestos and the urban dweller Ann NY Acad Sci 196 Dec 1965 20 Nicholson W.J. Asbestos- Asbestos- the TLV approach Ann NY Acad Sci 271 Dec 1976 21 Stanton M.F. Fiber carcinogenesis is asbestos the only hazard J Natl Cancer Inst 633 Mar 1974 22. Berry G. Combined effect of asbestos exposure and smoking on mortality from lung cancer in factory workers Lancet 476 Sep 1972 09778 LEGFE ORN FID GURS ES Figure 1 Typical scanning electron photomicrographs of particulate matter removed from thumbs and index fingers of laboratory workers A Aggregates from dry unheated ring liner Initial magnification was X50 B Aggregates from heated ring liner Initial magnification was X50 C Particles of dry unheated ring liner Initial magnification was X5,000 D Particles of heated ring liner Initial magnification was X5,000 Figure 2 Dispersive ray analysis of a single fiber component of an asbestos casting ring liner Figure 3 Typical scanning electron photomicrographs of debris from laboratory bench top and laboratory wall A field of bench top debris Initial magnification was X50 B field of wall debris Initial magnification was X50 C Linear component of bench top debris Initial magnification was X5,000 D Bundle of linear components of wall debris Initial magnification was X5,000 Figure 4 Fragmented debris from laboratory asbestos in storage drawer 09778 i ea ee ewTee ee ree 09778 <a PubA-09778 09778 PubA-09778