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tv E. I. du Pont de Nemours & Company iritmuta Maskcu. Laboratory aor Toxicology and Industrial. Medicine Eucton Road. Newark. Delaware 19711 CENTRAL. RCSCARCH ANO DEVELOPMENT DEPARTMENT C October 13, 1982 "i. L. ADAM 3. W. CULPEPPER C. C. GRIFFITH C. B. HAGERTY R. A. HARRINGTON T. E. LEWIS R. S. LIGO J. R. MARTIN T. J. NELSON J. L. PHILLIPS R. 0. RICHARDSON M. E. SABLA H. E. SERENBET2 K. A. SMITH -- ER BOD-1442 - ER - N-11400 - PHOTO - RSQ-210 - LEGAL w D-3048 - LEGAL - D-3044 - CtP ~ B-6216 - ER ~ N-11400 - ER - BOD-1442 - BIO - BARLEY MILL - LEGAL - D-7083 - BIO - BARLEY MILL - tf - N-4450A - PPD - M-5625 - PPD - M-5525 WORKING PROTECTION FACTOR STUDIES ON SINGLE USE RESPIRATORS FOR DUSTS Background information and the procedure for field studies on the effectiveness of single use respirators for asbestos containing dusts are attached for your information. Studies will be done during the last quarter of 1982. SWD/dar Attachment STEPHEN W. DIXON SECTION SUPERVISOR INDUSTRIAL HYGIENE iM-sm DU 030426 DUP 0913761 WORKING PROTECTION FACTOR STUDIES SINGLE USE RESPIRATORS FOR DUSTS Sack ground- On August 25, 1980 NIOSH issued s "Notice to All Respirator Manufacturers" which was subsequently published in the December 1980 issue of the AIHA Journal (attached). This notice questioned the effectiveness of air purifying dust fume and mist respirators (particularly single use) for asbestos and other carcinogenic substances. Two concerns were raised: ^ 1. The ability of the filter media to effectively remove the particulate. 2. The amount of leakage around the facepiece to face seal. In this letter they stated, "It is not our position that single use dust respirators will provide adequate protection against the cancer causing potential of asbestos." This proclamation raised serious questions on the status of current NIOSH approvals for these respirators for asbestos as a "fibrosis producing dust." DU 030427 OOP 0913162 Subsequent to this, one manufacturer of single use respirators, the Norton Company, issued a notice to users of their respirators on May 22, 1981, which stated that their single use dust respirator,should not be used for protection against asbestos dust but that an elastomeric half mask or full facepiece respirator with high efficiency cartridges should be used (attached) . S. w. Dixon contacted 3M, American Optical and MSA about their respirators and summarized findings in a November 5, 1981 letter (attached). No other manufacturers followed Norton's example but continue to recommend any respirator with current NIOSH approvals for asbestos. Though no filtering efficiency tests have been run for asbestos, they feel that it should be easier to filter asbestos dusts, consisting of rod shaped particulates, than the 0.4-0.6 um silica dust which NIOSH had used to test their respirators. Little data is available on facepiece to face seal leakage for disposable respirators. 1. A study done using a sodium chloride aerosol of 0.7 um mass median diameter showed protection DU 030428 2 DVP *13763 factors of 2 to 10 (mean of 5) for the 3M-8710 and 5 to 100 (mean of 20) for the AO-R-1050.^ 2. A working protection factor study on carbon setters in the aluminum industry for aluminum oxide, fluoride and carbon particulates showed protection factors of 2-1041 (mean of 16) for the 3M-9010.2 3. No studies have been done on asbestos dust. Though the performance of the filter matrix against long, thin asbestos rods would logically be as good as for the small particulates studied in the above studies, no experimental data is available to demonstrate effectiveness. A protection factor of five has been assigned to single use dust respirators, based on the studies above. Thus, protection would be afforded for up to 10 fibers/ce for chrysotile and 2.5 fibers/cc for amosite, based on their 1982 TLV's. Protection factors of greater than 5 are likely to be obtained by persons who are fit tested and proprerly trained , DUP 0913764 . DU 030429 in use of disposable respirators as required by OSHA standards and Du Pont guidelines. This would particularly be true for better fitting single use respirators such as the AO-R-1050 and 3M-9920. v.'orking protection factor studies will be done to determine wpp's for single use respirators for a good respirator program and to demonstrate effectiveness m response to NIOSH's notice. As a basis for comparison, studies to determine the WPF's for elastomeric half face air purifying respirators will be done to provide a basis for an alternate recommendation, should disposables prove ineffective. The objective of this work is to ascertain the types of respiratory protection which are effective against asbestos containing dust, to confirm that Du Pont practices are consistent with preventing occupational illness. Cost, maintenance and practical advantages of single use respirators favor their use if effective. -4 DUP 0913765 DU 030430 Procedure Train and fit test wearers using NPCA and 3M-F10 methods. Sample inside and outside of probed respirators during use (AO-1050, 3M-8710, 3M-9920, MSA Comfo II). Use 0.8 urn cellulose ester filters at a 2 Lpm sample rate. Analyze for asbestos fibers using the standard phase contrast method. Special cassettes from Glass Rock will be used to obtain uniform sample deposition for closed face cassette sampling (confirmed by laboratory studies). Check three pairs of inside and outside filters for small fibers (< 0.5 grn diameter) by transmission electron microscopy. Calculate WPF as fiber concentration outside fiber concentration inside Define WPF distribution and determine a safe assigned protection factor. Study sites: Glenolden (insulation removal). Corpus Christi (caustic/chlorine cell work) and Kingston (insulation removal). DU 030431 -5- DUP 0913766  Sample size: minimum of 3 WPF for each of 3 test subjects for each respirator, additional WPF for best candidates . Based on the WPF study results and a review of Du Pont site airborne asbestos levels, an AEL may be needed to resolve discrepancies in limits for asbestos by OSHA and ACGIH. References 1. Lowry, P. L., Hesch, P. R. and W. H. Revoir, "Performance of Single Use Respirators," AIHA Journal, 38 (9):462-467 -- <1977>* 2. Fergin, <3. S., "Respirator Evaluation for Carbon Setters, presented at American Industrial Hygiene Conference, Cincinnati, Ohio, June 9, 1982. SWD/dar 9/29/82 - DU 030432 dup 091376'7