Document R2pqGqG1eN9YZR781Opbj9rpn

hahlent tabestoe Concentrations Casa Mo. 48106-3 Ambient atmospheric concentrations of asbestos have not been exaained as intensively as indoor air levels. Ambient concentrations range Iran 0.01 to 0.1 ng/fc3 for rural areas and 0.1 to ?0 ug/to3 for urban areas. Fifty percent of urban residents are exposed to 30 ng/n^ (0.0004 optical fibers/cc). Connecticut has adaptad an ambient air quality standard of 30 ng^3 far a 30 day period. Current aethods far analysing asbestos air filtars are inaccurate at low ambient levels. Asbestos is the generic name for a elass at natural fibrous silicates with four ci swan: tally important forms: chrysotile, amen its, vthophylllte, and croci3olite. Chrysotile ccmpoeed 94% of the O.S. eonsoaption in 1974. Sabastoa Is currently used in sore than 5000 products including roofing, thermal, and electrical insulation, event pipe and sheet, flooring, gaskets, friction uaterials, coatings, plastics, tsxtiles, and paper products. Total production of asbestos dropped to 300 niIlian pounds in 1979, as suitable substitutes are developed. Biman exposure to asbestos occurs primarily by inhalation, althcMgh ingestion of fibers is considerable. Asbestos is so videly used that the entire population is exposed to some degree. Worker exposure occurs during the mining and milling of raw asbestos, manufacture of products and in the construction and ship building industries. 0SHA reports that about 2.5 nillion vokers are estimated to be exposed to asbestos. The general population is exposed to asbestos from air, beverages, drinking water, pharmaceutical and dental preparations, and consumer products. Families of asbestos workers have been exposed to high fiber levels through contaminated clothing which is laundered at heme. LLA 000736 -2- Asbestos fibers are released Into the environment by the wearing and deterioration of asbestos product* and the natural occurence at fibers in the earth. Major sources of atmospheric Missions include sines and silling facilities, sanofsctaring plants and vehicle brake linings. The application or deteriaration of asbestos containing fireproofing and insulating saterlale creates elevated Indoor levels of fibers. The renewal and disposal of building saterials releases asbestos into the anvtrwant. Asbestos levels in the workplace were originally restricted to a oMxisia concentration of 5 eppef by the Walsh-Healy Act of 1951. Nkaeeraus revisions at occupational asbestos standards have taken place with the current OSHA limit effective oe July 1, 1976. The 8-hour time-weigh ted average (TW) is 2 fibers greater than S a in length per cubic centiaeter of air. The celling value is 10 fibers greater than S taa in length per cubic centiaeter of air. The 8-hour TWA corresponds to a general public exposure of 25,000 ng/3 of asbestos. ' This is approximately 1000 tines greater than pravailing urban asbient levels. In 1977, the Consiater Product Safety CaMission restricted the use of asbestos in products by regulating patching cenrounds, gas fireplaces, and hand-held dryers. The EFA regulates asbestos under the Clean Air Act, Clean Hater Act, Tcocic Substance Control Act (TSCA) and Resource Conservation and Rtcwsry Act (RCM). The National Mission Standards far Hazardous Air Pollutants (HESHAP) reduced asbestos Missions by engineering and practice controls, Ambient air quality standarda for asbestos have been adopted by stse states (i.e., Connecticut). DlscussTbn **~i----------** 1r- have eeasured atmospheric asbestos concentrations in urban and rural areas. Philadelphia, Los Angeles, and Manhattan have asbestos levels ranging from 8 to 100 ng^^ (0.00016 to 0.002 optical fibers/cc) during the early 1970's. Boston had a lower average asbestos level of ^.0 ng,h3 (0.0001 optical fibers/cc) when eeasured by Nicholson et al, 1975. Mi intensive aebient monitoring program was conducted in Connecticut between 1974 and 1977 by Brucknan and Rubino, 1978. Asbient chrysotile asbestos levels in both urban and rural areas were bela 10 Saaples collected near industrial sources and adjacent to toll plazas were elevated\o the 10 to 25 ng/a3 range. The highest level of 41 rq/to3 vag meacured at a site near an urban toll station and ore of the largest industrial arbestos users in the state. The prevailing levels .ore "relatively low indicating the aabient asbestos problea is limited to peculations residing in close proximity to point sources of asbestos 'nissions* . W-A 000737 3 An indoor survey portarmed daring the Connecticut study suggested that tbs public health risk posed fay asbestos containing surface costings *may sot bo as great as previously thcwghtV indoor asbestos levels wars measured be lew 1 ng/*3. Ssvaral stadias have coopered asbestos levels Inside buildings containing spray asbestos and outsida air. Asbestos levels are directly related to the type, composition, and integrity of spray coatings in ccabination with sir change and circulation rates. A person working in a building with fibrous spray asbestos inhales 45% more asbestos than the aodian exposure level of 20 ng/W3 for urban populations. Nicholson et al, 1975, reported an average asbestos concentration of 2.5 og/to3 inside the JFK Building verses 5.0 ng/*3 in outside air in Boston. ) ftanerous surveys af asbestos levels have been perfumed by Bell Laba personnel. Although they focus on indoor air levels, asb ent samples were collected far a basis of comparison. Ambient concentrations ranged from 0.01 to 0.08 optical fibars/cc. The highest level was measured in Camden, New Jersey on February 23, 1976. Asbiint concentrations measured during Bell System industrial hygiene surveys ars cansidsxably higher than thorns io the literature. The major factor contributing to this difference is tbs sapling and analytical methods. Bell labn industrial hygiene surveys collect short term periodic saaples which are analyzed by qitical microscopy. Bm lonr limit of reliable seasureaent of this inOSH analytical aethod of fiber counting is 0.1 fiber/cc. Aebient atmospheric studies collect long term (monthly) samples at low toIibm and analyze the filters by electron microscopy. The accuracy at electron microscopy to determine concentrations in ng/a3 ranges is 'likely to be within 50% of the actual value and certainly within a factor of two". Conclusions \ Indoor and outdoor concentrations of asbestos are highly variable and directly influenced by the specific location, sapling duration, .. collection andKanalytical methods. The validity of ccnpariscns between various sites and studies is questionable. The ERA does not perform routine sampling to ccnpile a nationwide ambient database for urban asbestos levels (personal cur-unication with H. Steeker of Region II, ERA and H. Davis of Region I, ERA). EFA regulations have been proposed governing the renoval of indoor asbestos containing naterials. LLA 000738 -5 - References 1. Michaels, L., and Chiaelck, 8. 8. (1979), Asbestoe, Properties, Implications and Haaarda, Mon-Occupational Asbestoe filiations and Exposures, Qtapter 5, pge. 171-205. 2. National Toxicological Program (1981), Carcinogens, Asbestos, Research Triangle Park, NTIS PB 82-229808, pga. 37-41. 3. Brockman, L., and Rubiao, R. (1975) "Asbeetost Rational* Bahind a Proposed Standard," Journal of Bir Pollution Control Assoc. 25(12)1207-1212. 4. Bruckaan, L., and Rubino, R. (1978) "Monitored Aabeatoa Concen trations in Coonacticnt," Journal of Air Pollution Control Assoc.28(12) 1221-122*. 5. Ball Syataai Occupational Health and work Group (8SGRWG) . Baa*line Environmental Study, Volute 1, Mo. 1, November, 1975 to 1976, Asbestos Snarling and Results. 6. Bell Laboratories (1976) ATST Long Lines Baseline Industrial Hygiene Survey, Department of Environmental Health and Safety, Hurray Bill, New Jersey, Asbestos Saapling and Results. 7. National Institute of Occupational Safety and Health 01X061) (1977) Analytical Nethod for Dateraining Asbestos Fibers in PtCAM 239, Voliam 1. 239-1 to 239-21. V 1-LA 000739