Document KRpDMbGnkzMgE2YMB13JZMKEQ
FILE NAME: Kaiser Gypsum (KG)
DATE: 1966
DOC#: KG093 DOCUMENT DESCRIPTION: Report - Documentation of Threshold Limit Values American Conference of Governmental Industrial Hygienists
Documentation of
COMMITTEE ON THRESHOLD LIMIT VALUES
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Hygienists
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Copyright 1966 by
American Conference o f Governmental Industrial Hygienists
Re fere n ces:
1. Henderson, Y ., Haggard, H.W.: Noxious Gases, Reinhold Publishing C o ., N.Y.
(1943). .
______ _________
2. Nau, C .A .: South. Med. J . 41, 341 (1948).
3. E lk in s, H .B .: Chemistry o fT n d u stria l Toxicology, Wiley & Sons, N .Y ., (1959).
4. Bulmer, F .M .R ., et a l . : J . Ind. Hyg. & Tox. 22, 111 (1940).
ASBESTOS
5 mppcf
Asbestos is a generic term applying to a number o f mineral s ilic a te s that are incombustible in a ir and can be separated into filam en ts. The most widely used in
industry is ch ry so tile , a magnesium s ilic a t e frorr serpentine. Other types include amosite (an iron magnesium s i l i c a t e ) , cro cid o lite (a sodium iron s il i c a t e ) , trem olite (a calcium magnesium s ilic a t e ) and anthophyllite (also an iron magnesium s i l i c a t e ) .
M ille r and Sayers (1) showed that intraperit^neal in je ctio n o f amosite, chryso t i l e and cro cid o lite in guinea pigs produced the reaction o f an inert dust. Vorwald
et a l . (2) confirmed th is fo r short fibers (under 3y) but observed that long fib ers produced a fibrous reaction . Continuing unpublish ;d work by Gardner, these workers demonstrated that long fib ers (20 microns and abo/e) produced peribronchiolar fib ro sis in lower animals, and developed evidence that thi . resulted from mechanical rather than chemical action. Asbestos dust containing 0.t> per cent fib e rs longer than 10 microns, in concentrations o f 138 mppcf (or 0 .8 m llio n "long" fib ers per cu. f t . ) , was capable o f producing experimental asbestosis n guinea p ig s. When the concentration was 6.7 per cent fibers over 10 microns, 40 mppcf (equivalent to 2.7 m illion "long" fib e rs per cu. f t . ) , the reaction developed in apfroximately h a lf the time.
That exposure to asbestos is associated with development of a p oten tially d is abling pneumoconiosis in man has been amply demonstrated by industrial experience,
( 3 ,4 ,5 ,6 ,7 ,8 ,9 ,1 0 ,1 1 ). The present threshold lim it was recommended by Dreessen e t
a l . (8 ), a fte r study o f 541 employees in three asbestos t e x tile plants using chryso
t i l e . Only three doubtful cases o f pneumoconiosis were found in those exposed to dust concentrations under 5 mppcf, whereas numerous well-marked cases were found
above 5 mppcf. Counts were from im pinger-collected samples in ethyl alcohol and d is
t il l e d water. Both fibrous and nonfibrous p a r tic le ; were counted, but the la t te r greatly predominated. While chemical analyses o f c ille c te d samples o f air-borne dust corresponded to those o f se ttle d dust samples, i t is believed that dust counts o f p articu lates by conventional methods can be expectid to give only an in d irect measure of the risk o f asbestosis because o f the great r e lit iv e importance o f long fib e r s .
References:
1. M ille r , J.W ., Sayers, R .R .: Pub. Health R ep., 56^, 264 (1941). 2. Vorwald, A . J . , Durkan, T .M ., P ra tt, P .C .: Ard , Ind. Hyg. 1 (1951). 3. Merewether, E .R .A .: J . Ind. H yg., 12_, 198-239 (1930). Pneumoconiosis A bstracts,
1926-1938, Vol. I , p. 128. 4. Wood, W .B., Gloyne, S .R .: Lancet, Dec. 22, 19C4, pp. 1383-1385. 5. Fulton, W .B., Dooley, A ., Matthews, J . L . , Houtz, R .L .: Penn. Dept. Labor and
Ind. B u ll. 42 (1935). 6. Lanza, A . J . , McConnell, W .J ., Fehnel, J.W .: Pub. Health Rep. 50^, 1 (1935). 7. Donnelly, J . : J . Ind. Hyg. & T o x., 18, 222 (1936). 8. Dreessen, W .C., D a lla V a lle , J .W ., Edwards, T . I . , M ille r , J.W ., Sayers, R .R .:
Pub. Health B u ll. No. 241, Washington, D .C ., 1338. 9. Lynch, M.: Arch. Ind. H ealth, 1^, 185 (1955). 10. Smith, K.W.: Arch. Ind. Health L2, 198 (1955). 11. C a r tie r , P .: Arch. Ind. Health 11, 204 (1955).
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