Document Rj0Q5Dkogjr4jQBrw3131M0O7

`.v .i'i "i r. V A i Payr :>J6 INDUSTRIAL MEDICINE Xcvembt'r, 15. Maximum Allowable Concentrations of Industrial Atmospheric Contaminants --Prepared by Warren A. Cook, Director, Division of Industrial Hygiene and Engineering Research, Zurich Insurance Companies; formerly President of the American Industrial Hygiene Association and Chairman of the American Public Health Association's Committee on Standard Methods of Analysis of Industrial Atmospheric Contcminants-- issue. I: is acivAthat these be carefully read as a bah ground to the application of maximu allowable concentrations. It is to be emphasized that the : tent in presenting: these maximu allowable concentrations is to prcvh a handy yardstick to be used as gu: T"'' H following taoie presents a list of maximum allowable concentrations c: industrial atmospheric cor.cam j. nsncs as set up by a number of states, Maximum Allowable Concentrations of industrial Atmospheric Contaminants and includes the values recommended, ; T n all column* except I, the figures by the U. S. Public Health Service -* in this (Able refer to parts of gas or and the American Standards for sub ' vapor per million parts of air (abbrestances so far promulgated by the ' viatsd in the di.-custior. which follows American Standards Association. A a? ppm.) with the exception of the iist of accepted and tentative values . figures for dusts, fumes and mists is also presented for practical use in . which are expressed as milligrams of the control of occupational disease and the substance per cubic meter of air for the provision of both healthful ` (abbreviated as mg., nr). Ah' figures and comfortable working conditions expressed in units of mg./ir.1 in col where toxic or obnoxious materials may umns A through K are designate." with ar. asterisk. Under H, the first column include1 values normally expressed as parts per million. The second column, gives round number equivalents in milli grams per cubic meter so that there may be a comparison between the ioxicities of the various substances or. the basis of mass per unit volume. be present. A number of these values ' A B C i D : F- ! F 1 0 K ; r are soundly founded on a combination of animal experimentation and ex perience with workers under actual in dustrial conditions. Others of these ' Acetaldehyde........................ Acetic acid............................ Acetone............................. 50<t 1i 10 ! - ; 500 1000 , C.On j 1 200 : ! ppm nu; .'/n1 i 200 4C0 10 25 1 ; 500 loco values have a basis only in animal ex Acetylene tetrachloride (See I. .2. 2--Tetrach ioroe char-e i ,1 perimentation, some of which is so : Acrolein................................ AcrvUmicrUe........................... ! 2i) limited as merely to give an indica Ammonia.............................. root 1 3..1 | 1 20 20 ! 20 100 100 100 500 too ; 0.5 1 20 100 1 50 50 tion of the approximate concentrations Amyl acecate........................ 400i 200 400 400 -.'CO ; 400 200 1000 which should be permitted. Still others of these values are based on judgment which has its foundation in sensory response of persons to known concen trations of the atmospheric contami nant or in human experience under occupational conditions of insufficient extent to be truly significant. The final column of accepted and tentative values is offered with the iso-Amyl aienhoi................... ! Aniiine.................................. Arsenic..................... ............ Arsine................................... Barium peroxide (as Ba>.... Benzene (Benzol).................. Bromine................................. 1, 3-Butadiene........................ n-Butanol (Butvl alcohol).... 2-Butanone............................. ! n-Btity! acetate. ..................... 2001 200 55.65 1 3! 5 5 5 5-7 * 5 | 0.15* 0.15* 0.1S*,; 0.15* 0.5* I 0.05 l 0.5 l 0.5* 100 100 75 50 75 75-100 1000 1000 1000 M5, 1 0.5*100 100 I II 200 51) 200 5001 300 100 100 i1 400 200 400 400 400 400 I-. 100 5 1 100 l 5000 50 200 200 400 20 0.15 2 0.5 200 5 10000 200 500 >000 hope that further work both in the Butyl cellosolve...................... 50 experimental laboratory and under i Cadmium............................... t Carbon dioxide....................... 0.1* 0.1* 50001 0.1' 0.1* 0.1* 5000 5000 industrial conditions may be stimu Carbon disulfide...................... 20 20 20 20 20 lated. Already correlation of medical Carbon monoxide.................... 1001 100 100 100 100 findings, both clinical and laboratory, Carbon tetrachloride............... lOOi 100 SO Carrene No. 2 (See Monofiuorotrichloromethane) 75 50 with the results of determinations of Cellosolve............................... 500 0.1* 5550 20 100 100 500 ; 0.1* (0.1P 5000 20 20 100 100 100 200 v 5 000 20 W0 10 0 ) 2001 icoo 0.1 10000 50 100 500 1C00 concentrations of atmospheric con Cellosolve acetate................... taminants have given us much infor Chlorine.................................. 1 1 1 l l 1 100 \ 500 2 5 \ 10 mation. Only through further corre 2-Chlocohutadiene (Chloroprene > 83 25 \ 100 lated activity of this type can we arrive at more complete dependable Chlorodiphenyl....................... Chloroform............................. Chlotonaphthalenes............... 100 5* l* 0.3* 100 1-5 1* 100 \1 IQQ \ SCO \ information on these maximum allow fSee Penta and trichloronaphthaler.es) 1 able concentrations. It is advised that there be medical observation of work I-Chloro-I-nicropropane.......... Chromic acid........................ 0.L- 0.1 Cyclohexane........................... 0.1* 0.1* 0.1- 0.1* 0.1* 0.1* , 20 400 \ 100 0.1 11000 ers whose exposure to an atmospheric Cyclohexar.ol.......................... 1 100 \ 400 contaminant may be close to the al Cyclohexanone........................ i 100 1 400 lowable concentration especially where it may be one of those values based on such limited data as to be of ques tionable reliability. More complete discussions of the use ar.d limitations of maximum allow able concentrations are given by J. H. STERNER in INDUSTRIAL MEDICINE. 12, Cyclohexene........................... t^Dichloi'obeo2ene................. Dichiorcriltluurorae thane (Frfeon-12! ........................ I. I-Diciioroethaae (et'r.yiiduie chloride)............ 1, 2-Dichioroethane 'ethylene dichloride)............ 2-Die3*t>roethyiene.............. DicrJoroethy! ether................. 75 100 2O0 15 75 75 75 75 100 100 15 15 - i 400 , 75 V.'V'O pw i 100000 500000 1 100 ; 400 100 100 100 15 100 . 400 1 100 ; 4U0 | 15 / 100 51-1-518 (August, 1943), `'Determining Margins of Safety--Criteria for De fining a `Harmful' Substance"; by ludwig TELEKY in Industrial Hygiene Supplement of Industrial Medicine 9, 63-71 (October, 1940), "Toxic Lim its"; ana in an editorial on pages 53, From the Appendix of the forthcoming book. "Job Placement of the Physically Hanoi- capped." by Clark D. Director of Conservation Service.-. Zurich Insurance Com- f.anies. to be published by the MvGra-.v .HI!: Look Co-.v-iry ;n 1 ;4. DicV.loromethar.e.................... Dich.!oromoQ''>fJ<JCiromethine l, l-Dichloro-l-nicroethane . . Dichlorotetrafluoroechane (Freon-114;....................... Dificoromonochloromethane (Freon-22)....................... Dimethylaniline...................... Dimethylsulfate........ ........... ; Dinitrotclucit* 1 Dicxane........ ; Ethyl acocaw . . . . 1 Ethyl uier/vd.... r.--: 200 5 500 $5 5 1.5'| : -o | 500 2000 1 5000 ' 200x0 | 10 / 50 10000 i I ei)nOO :5 i 50000 50O0<1 -5 ....._d 1.5 F[ Ztt.y! bromide. ............................. ; 1700 *:hy! chloride..................................;20000' i roo ; ; | i 20000 Ethylene chiorhyd,-in....................1 .; 'chyleae dichiotide .Commercial name for 1. 2-D;.chiuroe:hane' `ylene oxide.................................! ' <250 ayi ether................................. 4001 400 : 400 400 400 Ethyl formate.................................. \ j Ethyl silicate....................................j ,, [ ' <500 ; Fluoride dusts, smokes .............. i Formaldehyde................................. ; r | 1** j 2" 10, 10 i 10 . 5 , 10 20; Freon (See respect;-.- D'.chloro, Diiluo.-o and Mor.otiuoro Co mpour.de; furfural................................. ; 11 :: C-asoliae..............................................1 'OOCXOOO 1000 1000 S00 1000 1000 Septan................................................ Hexane................................................:' ` ppn 500 5-'-00 ID ; too 500 200 !oi) *7 *' 2000 10'MO 25 200 2000 500 2000 10 to 10 See note ; 500 2C00 ' 500 2000 i 1000 4000 Hexasone (See methyl butanoae) ; E3m ,'See methyl tsobutanone) Hydrochloric odd j .hydrogen chioride`>...................! 10 2 10 20 3 10 20 1.5 20 20 20 Iron oxide........................................ 10 10 Ifl 33 20 20 l 05-1.0 00* 10 20 3 20 :c vt 3 20 \ ' 20 0.15* 0.15* 0.15' 0.15* 0.15* 0.15' 15* 5- S* 6* 8* S' 5-50* 0.L* 0.1* 0.1' 0.1' 0.1*!0.i-0.2': 0.15* 3,15' {6- 0.1- 0.1* Kvckv't b'jzaaoae........................... 200 200 200 200 100 100-20C 400 500 35 35 50-100 <1500 200 200 i : , Methyl ceilosolve............................ <25 500 100 500 Methyl cyclohexanol..................... Msthylcyclohexanoae................... Methyl ethyl ketone (See 2-8ut.moce) Monochiorobenzeae....................... 75 75 75 <1500 1000 75 75 L0 20 3 0.1 20 0.1 25 50 200 100 20 200 100 100 200 1000 100 100 400 200 75 10 20 2 .2 20 1 30 too 0.15 15 8 0.1 200 200 200 50 500 1000 500 400 4000 500 500 1000 600 400 onoduorocrichlorotne thane (Freoa-11--CarreneA2).......... Naphtha (Coal tar)....................... 100 200 Nitrobenzene.................................... N'itroechaae...................................... Nitroglycerine................................. 5 25 25 5 10 200 500 55 5000 1-3 40 25 10-40 10-40 5 $ 25 05 1.0* 1 0.5' 0.5' Pentanone (methyl propaaone) 500 Perchlorethylene (Commercial name for tetrachloroethylene) Phosgene.............. .............................. Phosphine.......................................... 11 1 1 11 11 Phosphorus trichloride................. 1 1 0.5* 1500 1 2 0.7 10000 5 100-200 500 5 200 50000 25 200-500 2000 25 500 25 25 100 0.5 5. 200 500 1 5000 400 500 2000 2 0.5 10000 1000 15 1i 0.5 4 iso-Propanol (iso-Propyl alcohol).......................................... Propyl acetate................................. iso-Propyl ether.............................. Radon (radium emanation) ... Sribtne................................................. Stoddard solvent............................ Styrene monomer........................... 750 400 400 400 400 400 Sulphur chloride.............................. Sulphur dioxide............................... 10 10 to 10 to to (400; 400 1000 200 1000 500 2000 10-- 11 curie/1 10 50 500 2000 400 1000 15 10 25 Sulphuric acid................................. Tellurium.......................................... 1, 1, 2, 2-Tecrachloroethane... . Tetrach'ioroethylene...................... Toluene (Toluol)............................ Toluidine............................................ Trichloroethylene........................... Trichloronaphtha'sene................... Trinitrotoluene (TNT)................ 1C 200 1.5* 200 200 200 200 10* 1.5* 5* 5 10 10 200 200 200 200 200 200 200 200 200 5' 5* 5* 2' t.5* 2 to 200 200 200 5* . 1.5* 10 200 200 200 200 1 5 0.01 10 50 200 1000 1.0 200 500 0 20 200 1000 5 1.5 'urpentine........................................ Vinyl chloride................................... Vinvl cyanide (See acrylonitrile) 200! TOO Xylene (Xylol).............................. 200 200 I 15*! 200 200 200 200-70C 500 200 200 200 15*1 15* 200 18* 200 (O.lr 200 (200 IS* 100 500 1000 1000 0.1 roentgen 200 500 L5 NOTE: A number Ol gases, sueu as acetylene, octane, euiuae. etu^ ,ene, ii}w|tu, nisv.--.t, helium and nitrogen, are considered to be essentially non-toxic hut act as simple asphyxiants at high w.or,r rations ance foi- "he roukr.e induiiriui cor.cvo! o: these health hazards--r.oc that compliance with the figures listed would guarantee protection against ili health on the part of exposed workers, nor should the maintenance of the suggested concentrations be considered a substitute for medical control. In every case, the concentrations given are considered allowable for prolonged exposures, usually assum ing a 40-hour week. The several lists in the table refer to the isilowing sources: A. California Industrial Accident Commission, September, 1945. 2. Conneccicuc State Department of Health. Bureau of Industrial Hy giene. Regulation '2S1 of the Sanitary Code. September. 1S45. C. Massachusetts Department of Labor and Industries. Mot oif.cial, but used by the Division of Occupational Hygiene as a guide. September, 1345. D. Mew York State Department of Labor. Mcc official, but used by the Division of Industrial Hygiene as a guide. June, i.945. E. Oregon State Board of Health. Rules and Regulations for the Pre vention and Control of Occupational Diseases. .August, 1945. F. Utah Department of Health. Compiled by the Industrial Hygiene Division as part of a booklet on `'Use ful Criteria in the Identification of Certain Occupational Health Haz ards," 1945. G. United States Public Health Service. Presented as a guide for occupational disease control, as pub lished in "Manual of Industrial Hy giene," W. B. Saunders Company, Philadelphia, 1943, with revisions here to show U. S. Public Health Service opinion as of September, 1945. H. American Standards promul gated by the American Standard Association up to September, 1945. Parentheses indicate value is an "American War Standard" only.. I. Accepted ana tentative values based on industrial experience, animal experimentation, sensory responses of persons, or a combination of these. Following the table is an indication of the basis and reliability of each of the values given, in Column I. Since there is no fine line cf demarcation be tween physiological response to small differences in concentrations of any of these atmospheric contaminants, round numbers are used in most in stances. For example, if 1000 parts per million of a contaminant such as gasoline vapor cause irritation but somewhat lesser concentrations--per haps 750 or 825 parts per million--do not cause irritation of some group of persons under observation, the allow able concentration is giver, as 500 parts per million rather than an inter mediate value. Basis of Values In Column I. Acetaldehyde: Iwanocf, in Arch. f. - J- Hyg., 73, 32 (1911), reported that cats showed no noticeable effects on -.i cait tc j.-^r mentations pucr.sr.eu under tr.e gen million. The value of 200 ppm is based on this brief exposure since the im mediate irritative effect of low con centrations appears to be more promi nent than systemic effects. Acetic Acid: 10 ppm is based on sensory response to this irritant. Acetone: This substance is one of' the least toxic of the commercially used solvents as has been shown both by industrial exposures involving many hunch*eds of persons and also eral title "Toxicology of Acrylonitrile u';.u.-:i'.UHlun 01 U.O (Vinyl Cyanide)" as follows: H. C. per cubic meter (as barium) has W* Dudley and P. A. Neal, "(I) A Study suggested by the U. S. Public Health of the Acute Toxicity," J. [nd. Hyg. Service as a guide. Where workers & Tox., 24, 27-36 (February, 1942) ; are exposed to concentrations an H. C. Dudley, T. R. Sweeney and J. W. proaching this value they should be Miller, "(II) Studies of Effects of placed under medical observation: Daily Inhalation," J. Ind. Hyg. A: Benzene (Benzol) ; Though 100 ppm Tox., 24, 255-258 (November, 1942); has been adopted as. the American A. H. Lawton, T. R. Sweeney and Standard, there is evidence that poj. H. C. Dudley, "(III) Determination soning has occurred at less than 100 of Thiocyanates in Blood and Urine,". . ppm. The National Safety Council f i S' o' N 5' C1 ; c< J I* ; 2 through- animal experimentation. From the point of view of' toxicity, an allowable concentration of even 2000 J. Ind. Hyg. & Tox., 25, 13-19 (Janu Study of Benzol Poisoning, as sum ary, 1943). . marized by C-E. A. Winslow in j Ammonia: The authority for 100 Ind. Hyg. <* Tox., 9, 61 (1927), th ia or 3000 ppm may be lower than r.eces. sary. H. Specht, J. W. Miller and P. J. Valaer, in Reprint No. 2076, Pub. Health Repts., 54, 044-955 (June 2, 1939), "Acute Response of Guinea Pigs to the Inhalation of Dimethyl Ketone (Acetone) Vapor in Air," reported that 1% acetone vapor in air for approximately 48 hours caused systemic injury to experi mental animals. The tentative value of 500 ppm is based on sensory re ' sponse to acetone vapor which caused irritation of the eyes, nose and throat of a group of human subjects at con ppm goes back to K. B. Lehmann, in Arch., f. Hyg., 5, 68 (18S6). This con centration is generally accepted today. Amyl. Acetate: The value of 200 ppm is based on irritative effects as reported by Nelson, et al. in the "Sen sory Response" paper, J. Ind. Hyg. <& Tox., 25, 282-285 (September, 1943). Amyl Alcohol: The value of 100 ppm is based on irritative effects as shown by Nelson, et al., J. Ind. Hyg. & Tox., 25, 282 (September, 1943). ' Aniline: W. F. von Oettingen, in Pub. Health Bull. 271 (1941), "The Aromatic Amino and Nitro Com technical data of which was published by L. Greenburg, in Reprint No. 1096 Pub. Health Rents., 41 1367, Hio' 1519 (1926), concluded that a substan tial hazard is involved even where the average exposure is below 100 ppm_ M. Bowditch and H. B. Elkins, in j hid. Hyg. <fe Tox., 21, 321-330 '(Octo ber, 1939), "Chronic Exposures to Benzene (Benzol). I. The Industrial Aspects," suggested 75 ppm as a maximum allowable concentration but cited two cases of poisoning where they believed the average exposure was below this concentration. It is O' a.- S N Oj , -d: . sc tc to et "O . of i cc V: PI centrations of 500 ppm as reported by K. W. Nelson, J. F. Ege, Jr., Morwick Ross, L. E. Woodman, and Leslie Sil- verman, in J. Ind. Hyg. & Tox., 25, pounds, their Toxicity and Potential Dangers -- A. Review of the Liter ature," stated that the available liter ature is not sufficient to allow the accordingly suggested that exposures be kept below 50 ppm until further experience either substantiates the suggested limit of 100 ppm as safe or P` b* a-. to 282-285 (September, 1943), "Sensory establishment of definite standards, causes it to be decreased. Response to Certain Industrial Solvent but quoted the table from Henderson Benzine: This term is applied to \ -c. Vapors." Although the exposed group and Haggard, "Noxious Gases," 1927, petroleum distillates such as gasoline. .M estimated 200 ppm as the highest sat in which 7.0 to 25.0 ppm are described See "Gasoline" for discussion. . J- isfactory exposure for eight hours, as giving slight symptoms after sev Bromine: Zederbaum, in Gig. Truda ' to it is felt that some habituation usually eral hours. Workers exposed to page 68 (1527), referred to by Koelsch pc develops on daily exposure to mod concentrations approaching the sug in Munch, mod. Wochschr., No. 33 al erately irritative atmospheres. In war gested value of 5 ppm should be under (1928), found 4 ppm in a workroom . th .i industries where hundreds of workers medical observation--particularly as to be productive of no noteworthy in - SC Jt i i were exposed to acetone, it was found (necessary to maintain vapor concen-. trations below 700 ppm to avoid irri aniline is readily absorbed through the skin. -' Arsenic and Arsenic Trioxide: The jury. An unidentified reference to K. B. Lehmann by Flury and Zernik in "Schadliche Gase," 1931, stated pv ; cc 1 se i tation. A number of state depart allowable concentration of 0.15 mgs. six hours' exposure to bromine was v ments have found it necessary to per cubic meter for metallic arsenic without noticeable symptoms at a con require limitation of acetone vapor to and arsenic trioxide was based on centration of 0.75 parts per million. H 500 ppm to avoid irritation. There is analogy with other metals such as The value of 1 ppm should receive no published evidence that concentra cadmium and lead in setting up the further substantiation. 1 re C tions of 1000 ppm are regularly toler American War Standard by the Butadiene: C. P. Carpenter, C. B. t-r ated without irritation, though in some American Standards Association. On Shaffer, C. S. Weil and H. F. Smyth, I cl large industries such concentrations are said to exist with no complaints by those exposed. Where irritative qualities of a substance are the decid ing factor in recommending a con the basis of long experience involving many occupational exposures, at least one large concern considers it permis sible to increase this limit to 5. mg. per cubic meter. R. M. Watrcus, Jr., in J. hid. Hyg. < Tox., 26. 69-78 (March, 1944) "Studies on the Inhala tion of 1, 3-Butadiene," concluded that concentrations cf 600, 2200, and 6700 ppm caused r.o significant progressive i e: xc cl xr. centration which may be appreciably M.D., and M. B. McCaughey, in injury to small animals during an Iv lower than the toxic limit, this fact Industrial Medicine, 14. ~ 639-646 eight months' exposure, although ths should be fully recognized in the ap (August. 1945) "Occupational Ex highest concentration retarded growth w SV plication of the suggested value. Acrolein: Since a concentration of 1 ppm of acrolein produces marked irritation of eyes and nose in five min posure to Arsenic -- In the Manu facture of Arspher.amir.e and Related Compounds--" reported that expo sures in manufacturing operations slightly and caused light cloudy swell ing in some livers. r:-3n:anoi: H. F. Smyth and H. F. Smyth, Jr., in J. hid. Hyg., 19. 261-271 e: ? c ? P 21 utes or less, as shown by W. ?. Yant, ranging from 0.007 to 0.60 milligrams (October, 1928), "Inhalation Experi H. H. Schrenk, F. A. Patty, and R. R. per cubic meter as As-CL resulted in ments with Certain Lacquer Solvents." u: F Sayers, in U. S. Bureau of Mines Re port of Investigations No.-3027 <, 193), "Acrolein as a Warning .Agent for De tecting Leakage of Methyl Chloride from .Refrigerators." a concentration of half this value is tentatively sug no clinical symptoms attributable to arsenic except in a few isolated work ers during a short period of unusually heavy exposure. A The value of 1 ppm is sug gested as a guide by the U. S. Public reported development cf pathology cr. ar.irr.al experimentation with expo sures at 100 ppm. I. R. Tabershaw. J. ?. Fahy, ar.c J. 3. Skinner, J. Ind. Hyg. < Tox., 26, 323-330 (December, 1944) "Industrial Exposure to 3u- \ v; iD TV ( iW W gested for prolonged exposure. .-He: The U. 3. Public Health Service suggests 29 ppm as Health Service. Flury and Zernik in "Schadliche Case," 1931, stated in an unidentified reference to K. B. Leh tar.oi," found that eye inflammation will result when atmospheric concen trations exceed'50 ppm ar.d that no rc n: no: definitely established but to serve mann that 3.1 ppm is tolerable for six systemic effects may be expected'beiow as a gride following animal experi hours without apparent symptoms. 100 parts per million. . ir ;N JLcTi'KiAL M EDIC1N F Page 039 . -Uataimnc: Although the acute re use of guinea pigs to butanone, as trved by F. A. Patty, H. H. -.renk and W. P. Yant, in Reprint . 1702 from Pub. Health Repts., * '-1223 (September 6, 1935), w lat 3000 parts per million Id volerated by animals for sev! hours without serious disturbance, Aon, et a!., in J. Ind. Hyg. & Tox., 232 (1943), demonstrated sufficient Itation to humans at concentrations .>50 ppm to recommend 200 ppm as Tactical limit. -Butyl Acetate: The acute response guinea pigs to normal butyl acetate, shown by R. R. Sayers, H. H. ;renk, and F. A. Patty in Reprint . 1769 from Pub. Health Repts., 1229-1236 (September 4, 1936), in cited the maximum exposure for eral hours with siight or no symp;s to be 3300 ppm. Sensory response this vapor, as shown by Nelson, in J. Ind. Hyg. <6 Tox., 25, 282 43), was severe throat irritation .vhich all subjects complained at a centration of 300 ppm. Though 100 !i was recommended by the exposed sons, a concentration of 200 ppm is 'g suggested, as this group was not nstomed to occupational exposure ;he material. ''tyl Cellosolve: H. W. Werner, >V. Nawrocki, J. L. Mitchell, J. W. ler, and W. F. von Oettingen, in id. Hyg. & Tox., 25, 374-379 (Oc:r, 1943), "Effects of Repeated Ex.irar Rats to Vapors of Mono:\ 4 ene Glycol Ethers/' found : exposures of rats to a range of to 400 ppm of n-butyl glycol ether iuced small but measurable toxigical effects on daily exposure of n hours, five days a week for five idmiuin: L. Prodan, in J. Ind. 14, 174-196 (May, 1932), "Cad- n Poisoning. II. Experimental Tiium Poisoning/' reported on exive animal experimentation in:ng inhalation. Although the low. concentrations used were much in ss of those considered poisonous continued exposure, it is to be con:-d from Prodar/s work that cadu is as poisonous as lead or somet more so. In view of the rapidity which excessive cadmium expoi can cause serious pulmonary .a and death, as shown bv L. W. -ar. J. ;. Keppier, and H. G. sr. in /. hid. Hyg. & Tox.. 26, 149 (September, 1944), "'Cadmi"cisor.ing in Industry: Report of Cases, Including One Death," tew exposure to cadmium dust or r should be carefully watched, ruination of concentrations to ; workers are exposed together medical observation of the :-rs ' important both for avoidfc injury and to gain more !e .formation concerning the rum allowable concentration, i-ort Dioxide: Flury and Zerrrlk, id-iche Case," 1931. refer to LehHess as authority that six ' exposure to 5550 ppm carbon dioxide caused r.o noticeable symptoms. Carbon Disulfide: F. H. Wiley, W. C. Kueper, W. S. von Oettingen, in J. Ind. Hyg. S: Tox., 18, 733-740, (1936), "On the Toxic Effects of Low Concentration of Carbon Disulfide," reported that animals exposed to con centrations of 30 ppm over a long term showed no significant toxic effects. N. L. Barthelemy, in J. Ind. Hyg. <ft Tox., 21, 141-151 (1239), "Ten Years Experience with Industrial Hy giene in Connection with the Manu facture of Viscose Rayor./' reported that no trouble whatever was experi enced where carbon disulfide exposures were kept in less than 30 ppm. Carbon Moiioxide: Y. Henderson, H. W. Haggard, M. C. Teague, A. L. Prince, and R. M. Wunderlich, in J. Ind'. Hyg. <& Tox., 3, 79-137 (1921), "Physiological Effects of Automobile Exhaust Gas and Standards of Ven tilation`for Brief Exposure," showed that 100 ppm could be considered al lowable for an exposure of several hours. R. R. Sayers, W. P. Yant, E. Levy, and W. B. Fulton, in Public Health Bulletin No. 1S6 (1929), "Effects of Repeated Daily Exposure of Several Hours to Small Amounts of Automobile Exhaust Gas," re ported that the daily exposure of six men over a period of 68 days to 200 ppm of carbon monoxide caused some of the more susceptible persons to develop slight but not discomforting symptoms after two hours. R. F. Siever?, T. I. Edwards, A. L. Murray, and H. H. Sehrenk, in J.A.hl.A., 11S, 585-588 (February 21, 1942), "Effect of Exposure to Known Concentrations of CO," reported that a group of 156 Holland Tunnel traffic officers ex posed over a 13 year period to an average of 70 parts per million of carbon monoxide aid not reveal any evidence of injury to health attribut able to the exposure. Carton Tcirackloinde: H. F. Smyth, H. F. Smyth, Jr., and C. P. Carpenter, in J. Ind. Hyg. < Tox., IS, 277-293 (1936), "The Chronic Toxicity of Car bon Tetrachloride: Animal Exposures and Field Studies," conduced on the basis of animal experiments over a period of 10vo months that 100 ppm is safe for continuous exposure of workmen throughout the cay, and day after day. There has been an in creasing amount of evidence since the date of that publication that con centrations of less than 100 ppm may cause ir.'urv to health. As ir. the case of benzol, it is recommended that ex posures be kept at less than half the maximum allowable limit for carbon tetrachloride until such time as fur ther experience either provides justi fication of the present suggested limit or causes it to be revised downward. Cclieso! re: H. V. Werner, C. W. Nawrocki. J. L. Mitchell. J. V. Miller, and W. F. von Oettingen. in J. Ind. Hyg. <C Tox., 25. 374-379 (October, 1943), "Effects of Repeated Exposures of P.ats to Vapors of Monoalkvl Ethy lene Glycol Ethers," found that ex posures of rats to a range of 300 to 400 ppm of ethyl glycol ether (cello solve) produced small but measurable toxicological effects on daily exposures of seven hours five days a week for five weeks. . Cellosolve Acetate: The maximum allowable concentration of 100 ppm is based on an unpublished report of tests made by the Chemical Hygiene Fellowship at Mellon Institute, re ported in July, 1945. Chlorine: Early work has indicated that 1 ppm should be taken as the maximum allowable concentration and this has been generally followed. P.onzani, Arck. f. Hygiene, 67, 2S5 (1909), showed that 1.7 ppm caused impaired nutrition and blood changes in ani mals, but that 0.7 ppm caused no disturbances. K. B. Lehmann listed in a table in 1912, quoted in U. S. Bureau of Mines Tech. Paper 243 (1921), that 1 ppm causes slight symptoms after several hours and 4 ppm is the maximum concentration without symptoms for one hour ex posure. As long ago as 1899, Lehmann observed that an increase in resistance occurs on acclimatization (Arck. f. Hyg., 34, 302). Capable research of more recent date in this.country con ducted by the American University Experiment Station of the Chemical Warfare Service, referred to in U. S. Bureau of Mines Tech. Paper 24$ (1921), showed the least concentra- tion to give detectable odor was 3.5 ppm; to cause throat irritation, 15.1 ppm; and to cause coughing, 30.2 ppm. On the basis of these data, it is con sidered in order to suggest 5 ppm rather than 1 ppm as the allowable concentration. Ckloro-butadiene (Ckloroprene) : W. F. vor. Oettingen, W. C. Hueper, W. Deichmarm-Gruebler, and F. H. Wiley, in J. hid. Hyg. & Tox., 18, 240 {1936), "2-Chlorobutadiene (Chloroprene) : Its Toxicity and Pathology and Mechanism of its Action/' re ported that animal experimentation indicates that continued exposure to 0.3 mgs. per liter (83 ppm) and even less may cause toxic effects. It is consequently considered desirable to suggest 25 ppm until further data are available as to effects or. man on prolonged exposure. Chlorodif.kcnyl: C. K. Drinker, in J. Iy\d. Hyg. < Tox., 21, 155-159 (May, 1839 i. "Further Observations on Pos sible Systemic Toxicity of Certain of the Chlorinated Hydrocarbons with Suggestions for Permissible Concen trations in the Air of Workrooms," lists a table of 14 chlorinated hydro carbons with permissible limits. Ex posure of rats to 0.5 mgs..nr/ in one test and 10.0 mgs./r.r in another was found to cause no injury. A maximum allowable concentration of 1 mg. .'nr is suggested, though it is very pos sible that exposure to this substance may extend to 5 mgs., nr without in jury to health. Chloroform: Since there is r,o pub lished work on prolonged exposures of animals under experimental condi tions or of humans in industrial oc t'z'JC ''AO cupations to known low concentrations of chloroform, a value of 100 ppm is generally accepted on the basis of analogy with carbon tetrachloride. The value as given should be further 'ubstantiated and there should be y.ose medical observation of any group of workers exposed to chloroform con. centrations approximating 100 ppm. As is the case with carbon tetrachlo ride, it would be wise to retain ex posures to less than 50 ppm until more data are available. Ckloronaphthalenes: Results of ani mal experiments with chloronaphthalenes are given in the reference cited under "Chlorodlphenyl." Inhala tion of a concentration of 10 mgs./m3 of trichloronaphthalene by rats caused no pathology. In view of the fact that industrial experience has indicated that there is an unusually marked difference in susceptibility, 5 mgs.m/3 is generally accepted as the allowable concentration. As the chlorine con tent of the compound increases, a lower allowable limit is necessary to avoid poisoning. For a combination of tetra' and penta chloronaphthalenes, a limit of 1 mg./m* was suggested; for a mixture of penta and hexachloronaphthalenes, a limit of 0.5 mgs./m3. 1 -Chloro-1 -nitropropane: Willard Machle, E. W. Scott, J. F. Treon, F. F. Hevroth, and J. V. Kitzmiller, in J. 7nd. Hyg. < Tox., 27, 95-102 (April, 1945), "The Physiological Response of Animals to Certain Chlorinated Mononitroparafhns," showed by animal experiment that this substance is con siderably less toxic than 1,1-dichIoro1-nitroethane. The longest exposure to the propane derivative was for two hours only. The allowable concen tration of 20 ppm for long exposures is based on a comparison with that of the ethar.e derivative on which more extensive research was done. Longer animal experimentation or human ex perience under medical observation may indicate that a somewhat higher concentration is not injurious. Cyclohexane: J. F. Treon. W. S. Crutchfield. J.. and K. V. Kitzmiller, in J. Ind. Hug. <- Tox.. 25, 323-347 (October, 1943), "The Physiological response of Animals to Cyclohexane. Methycycichexane. and Certain De rivatives of these Compounds.'- re ported that animal experimentation of 50 periods o: exposure of six hours each, showed barely demonstrable mi croscopic changes in the liver and kid neys of rabbits that had been exposed to 7S5 ppm and no toxic changes after similar periods of exposure to 434 ppm. As the pathological erects of the higher exposures were so slight, it is considered permissible to set the allowable concentration at 400 ppm. Cyclohexancd: The reference quoted under "Cyclohexane" includes similar data on cyciohexanol. These authors showed that 693 ppm caused barely demonstrable pathological changes or a monkey and that 2 4-5 ppm caused >canty but definite changes in the liver and kidneys of rabbits, with the con clusion that this latter exposure is INL)l -t . .ti AL .up!u iCih r. very near to the maximum safe level for rabbits. One hundred ppm is be ing suggested as the maximum allow able concentration but, until there is more experience with human expo sure, there should be medical observa tion of workers exposed to these com pounds where concentrations approach the allowable limits. Cyclohexanone: In the preceding reference these authors reported the maximum allowable concentration for cyclohexanone is. slightly below 190 ppm. A maximum allowable limit of 100 ppm is suggested for this com pound. In the experimental human exposures to cyclohexanone carried ort by Nelson, et al., and described in J. Ind. Hyg. & Tox., 25, 282 (Septem ber, 1943), irritation was experienced at 75 ppm. If actual industrial ex posures show similar irritation to workmen, the permissible exposure should be adjusted downward. Cyclohexene: The only quantitative toxicological work conducted on this compound is that, on acute exposures which N. W. Lazarew reported in Arch, ezptl. Path. Pharmakol., 143 223 (1929), "On the Toxicity of Va pors of Different Hydrocarbons," showing that 9000 ppm caused ex perimental animals to assume "side- position," indicating mild narcosis. On analogy to the toxicity of cyclo hexane which it closely resembles structurally, though introduction of a double bond may increase its toxicity somewhat, the maximum allowable concentration of 400 ppm is suggested. With this inadequate basis for setting an allowable concentration, medical observation should be afforded work ers who may be exposed to concentra tions approaching this value. o-Dichlorobenzene: A value of 75 pom is recommended by the U. S. Public Health Service as a guide. Dichlorodf.ifnorometha ne (Freon- 22) : R. R. Sayers. W. P. Yar.t. John Chorr.yak,- and H. W*. Shoaf stated in U. S. Bureau of Mines Report of In vestigations No. 3013 "Toxicity of Di- c'nlcrodinuoromethane: A New Refrig erant," (May, 1930) that a 12 week daily exposure of animals to 20% by volume of this vapor caused no gross pachcicgy attributable to the exposure. Since generalised tremor and a gait simulating alcoholic ataxia were ob served in some of the animals, it is recommenced that the maximum ex posure be no more than 10% or 100,000 ppm. _ _ 1.1 -uichloroeihcr-c (c-thylidine Chlo ride) : The value of 100 ppm is set up for this compound as its action is con sidered by "jury and Zerr.ix. "Schad- liche Gase," 1931. to be analogous to chloroform though less severe. The only reported animal experimentations are those by Lazarew and Mueller, who determined narcotic action of con centrations only as low as 7400 ppm and 4400 ppm respectively. Their work is reported in Arch. cxr-iL Pain, ph.i. .-r-akol.. 141. 19 C1924). and 109. 276 il?25'>. respectively. 1.2-Diehlor ox c <Eihy!crc ll'i- /KOcr, i p - chloride) : The value of 100 ppm }s recommended by the U. S. Public Health Service as a guide and is gen. orally accepted though there is sorne indication that somewhat lower con centrations should be used as the maximum allowable limit. Where ex posures approach this value, medical observation of workers is recom mended. Dichlorocthylene: The value of 100 ppm is suggested as a tentative value but no specific work has been done on prolonged exposure to known concen trations of this material. There has been some suggestion that the un saturated chlorinated hydrocarbons do not cause liver damage at as low con centrations as do the saturated com pounds, but specific information should be developed on this particular un saturated chlorinated hydrocarbon be fore the suggested value is increased to possibly 200 ppm. Dichloroetkyl Ether: H. H. Schrenk, F. A. Patty, and W. P. Yant, in Re print No. 1602 from Public Health Repts., 48, 1389-1398 (November 17, 1933) "Acute Response of Guinea Pigs to Vapors of Dichloroethyl Ether," re ported that slight nasal irritation was noted among experimental animals at 35 ppm. It has been generally ac cepted that where prolonged exposures are contemplated, the exposure should not exceed 15 ppm. Dichloronteihane: L. A. HeopeJ. P. A. Neal, T. L. Perrin, M. L. Orr' and V. T. Porterfield, in J. hid. Hyg. < Tox., 26, 8-16 (January, 1944), "Toxicology of Dichloi'omethane (Methylene Chloride)concluded that on the basis of animal experimentation the maximum allowable limit be tenta tively set at 500 ppm for eight hours daily exposure. Although Henderson and Haggard, in "Noxious Gases," 1943, quote F. Flury in Lehmann and Flurv, "Toxicoiogv and Hygiene of Industrial Solvents," (Williams & Wilkins, 1943) that 290 ppm should be a maximum allowable concentra tion, it is to be noted that the animal experimentation by Heppel, et a!., of the U. S. Public Health Service, cited above, showed that even at 5000 parts per million, repeated seven hours ex posures, five days a week for six months, caused no evidence of toxic action by rats, rabbits or dogs. Dich lorornon-ofiuoromctkane (Freon- 21): Shewn by the Underwriters' Laboratories Report MH 2330 (1935) and U. S. Bureau of Mines Report R. I. 3185 (1933) to be somewhat more toxic than monofiuorotrichicromethane (Treon 11) for which the value c: 10.000 ppm is suggested. l.l-Dichiorc-l-niiroeihane: '\ i.iaru Machle, E. W. Scott. J. F. Treer., F. F. Hevroth. and K. V. Kitzmiller. in J. Ind. Hyg. & Tox.. 27, Y5-102 (April. 1945), "The Physiological Response of Animals to Certain Chlorinated ?!c-no- nitroparamns." reported that expo sure of animals to 25 ppm was with -t lethal effect for 204 hours. Thc-y ob served that the irritation or. exp-rare to this compound was greater caused by equivalent concenrra- ns of di'ethyl ether but definitely than that resulting from equiva- :it exposure to acid gases. Dichlorotetrafluoroethane (Freon A H. Nuckolls, in Underwriters' ;i -iries Report MH-2375 (No- ;.n-t 1923), reported that animals .owed occasional retching movements ;-om which they recovered quickly :':er two hours' exposure to 2.5% of ;:is material, though no pathological .-nditions were found on autopsy after -.e two hours' exposure. There has :-en no published work on prolonged vposure. ! Dimetkylsulfate: Flurv and Zernik, Schadliche Gase," 1931, reported .-ithout giving specific reference to riginal work, that 20 ppm killed nts in 11 minutes and that 13 ppm aused severe poisoning on 20 minutes' xposure. On the basis of these ani- r.al experiments, a value of 1 ppm is uggested as the maximum allowable oncentration. However, there should y all means be close medical super vision wherever there may be exposure this dangerous substance.' Difinoromonochlororacthane (Freon _>) : Underwriters' Laboratories Re- ort MH 3134 (1940) concluded that his substance is less toxic than Freon 1 and than carbon dioxide but more .txic than Freon 12. DimcihylaniHne: The U. S. Public ealth Service suggests that this com pound is similar to aniline in its oxipitv. 1 ololuene: The toxicity of dini- roV^. .^ne is considered similar to that : TNT for which the U. S. Public iealth Service suggests 1.5 mgs. per. ubic meter as a guide. Dioxane: A. Fairley, E. C. Linton, .r.d A. H. Ford-Moore, in J. Hyg., 34, S6 (1934), "The Toxicity to Animals f 1.4-Dioxan," report kidney and Iver damage to animals on exposures : 100 ppm ever periods for the most art of 100 to 200 hours' duration, ersons who are exposed to dioxane at vneentrations approaching that con- idered allowable should be under .edical observation until more data re available concerning effects of nown concentrations. Ethyl Acetate: This material is mong the lesser toxic of organic sol- fr.ts but causes irritation of eyes. ;-se and threat to experimental hu- subjects at 400 rpm according to lelsor.. et a:.. :r. J. Ind. Hyg. .C- Tc-x.. 292 (September, 1942). Atten- .: should be giver, to complaints at xposures even less than this cor.cen- aticn as experimental subjects esci- ated that the ecrcc-rtratton would are to be reduced to '.00 ppm. to e considered satisfactory for eight ,-urs' exposure. Ei'--1 Alcohol: Although as reliable n ,rity as Lehmar.n and Flury, Tv k>gy and Hygiene of Indus- :r.l Solvents." (Williams d: Wilkir.s. 43) observed. without specific refer- ,cg. that 1000 ppm in the air is con- lered a dangerous concentration, rge numbers of workers in this e.untvy have been exposed over long periods of time to concentrations of 1000 ppm with no demonstrable in jury to health and with no increase in accident frequency. There is an occasional initial complaint of eye irritation but this is only on very first introduction to the exposure. Ethyl Benzene: W. P. Yant, H. H. Schrenk, C. P. Waite, and F. A. Patty, in Renrint No. 1379 from Public Health Repts., 45, 1241-1250 (May 30, 1930) "Acute Response of Guinea Pigs to Ethyl Benzene," found no symptoms other than eye and nose irritation on exposures of 1000 ppm for as long as 4S0 minutes. N. W. Lazarew, in Arch, exvtl. Path. Pkar~ makol., 143, 223 (1929), "On the Toxicity of Vapors of Different Hy drocarbons," reported that ethyl ben-' zene has greater narcotic action than benzene. Ethyl benzene thus com pares with toluene in its relation to benzene on high exposure and, from its structural formula, can be ex pected to correspond to toluene on extended exposure to lower concen trations. A value of 200 ppm is ac cordingly suggested. Where expo sures approach this concentration, there should be medical observation of persons exposed in view of the lack of specific data supporting this value. Ethyl Bromide: R. R. Sayers, W. P. Yant, B. H. G. Thomas, and L. B. Berger, in Public Health Bulletin No. 135 (March, 1929), "Physiological Response Attending Exposure to Vapors of Methyl Bromide, Methyl Chioride, Ethyl Bromide and Ethyl Chloride," observed that exposures of animals to 1700 ppm for 540 minutes caused no symptoms. In view .of the lack of experimental data covering exposure over prolonged periods or quantitative information on exposure of workers, a value of approximately one-quarter of the above concentra tion or 400 ppm is arbitrarily sug gested as a tentative allowable con centration. Where workers may be exposed to concentrations approaching this value, they should be under med ical observation. Ethyl Chloride: Public Health Bul letin No. 1S5 (March, 1529), cited as reference for "Ethyl Bromide." recommended 20,000 ppm as the maxi mum amount for long exposures. Fol lowing the same arbitrary rule as for ethyl bromide. 5000 ppm is suggested for ethyl chloride. Here again persons who may be regular'}' exposed to con centrations approaching this value should be ur.cer medical observation. Ethiene Chlorhydrin: Hugh Dierker and Paul G. Brown, in J. Ind. Hyg. & Tex., 20. 277-279 (October. 1944), "Study of a Fatal Case of Ethylene Chiorohydrir. Poisoning," found that the victim had been exposed to a con centration of 305 ppm for only two hours. Animal exposure to a. concen tration of 255 for two hours caused pathological conditions to develop. Until further data on effects of pro longed exposures are available, it is recommended that concentrations not exceed 10 r.pm. Particularly in view of the considerable skin absorption of ethylene chlovohydrin, as observed by H. F. Smyth, Jr., and C. P. Carpenter, in J. Ind. Hyg. & Tox., 27, 93 (March, 1945), "Note upon the Toxicity of Ethylene Chlorohyririn by Skin Ab sorption," workers exposed to this solvent should be under medical obser vation. Ethylene Oxide: C-. P. Waite. F. A. Patty, and W. P. Yant. in Rent. No. 1401, Pub. Health Rents.. 45.* 1S32- 1843 (August S, 1930). "Acute Re sponse of Guinea Pigs to Ethylene Oxide," found that 250 ppm caused no symptoms on exposure of animals for 480 minutes. With lack of long-time animal experiments and no published data on prolonged exposures of the workers at known concentrations, a value of 100 ppm is arbitrarily sug gested. Where workers are exposed to concentrations in the vicinity of this value, they should be under med ical observation. Ethyl Ether: In this country, large numbers of persons are at work in operations involving exposures of 500 to 1000 ppm and as high as 2000-3000 ppm without demonstrable effect on health. Unfortunately there has been no publication correlating prolonged exposures to these concentrations with medical findings--or lack of them. Nelson, et al., in J. Ind. Hyg. < Tox., 25, 2S2 (1943), reported nasal irrita tion at 200 ppm to persons under ex perimental conditions who considered that 300 ppm would be objectionable as a working atmosphere. However, this experimental group had no op.portunity for occupational acclima tization. The concentration of 500 ppm is suggested as the maximum allow able, not that appreciably more than this concentration cannot be reguiarly tolerated without injury to health, but to avoid irritation and complaint. Ethyl Formate: Flury and Zerr.ik in "Schadliche Gase." 1531. reported that 330 ppm causes slight irritation of the eyes and rapidly increasing nasal irritation. In view of the in adequate data available concerning exposure to this material, there should be medical observation of workers who may be exposed to concentrations in the vicinity of the suggested limit o? 200 ppm. Ethyl Silicate (Tetraethyl orih:Silicate) : J. .A. Rasper. C. ?. McCord, and W. G. Fredrick, ir. Industrial Medicine, 6. ?60-084 tl937). "The Toxicity of Organic Silicon Com pounds. I. Tetraethyi orthc-Silicate." reported that animals exposed to 164 ppm, eight hours a day for 17 cays did not shown weight increases equal to the controls, but mentioned r.c other indications of injury from this expo sure. H. F. Smyth. Jr., and J. Seaton, in J. Ind. Hyg. <& Tox.. 22. 28S-255 (September, 1940} "'Acute Response of Guinea Pigs and Rats to Inhalation of the Vapors of Tetraethyl Ortho silicate (Ethyl Silicate)," found that concentrations as low as 245 ppm gave rise to some pathology ir. animals M iiJ i:f rKM after several hours exposure. An al lowable limit of 100 ppm is suggested for prolonged exposure, but with the lack of industrial experience at known concentrations, any workers subjected to an exposure approaching 100 ppm should be under medical observation. Fonnaldehyde: The principal effect of exposure to low concentrations of formaldehyde is irritation, especially in the nose and eyes with lachrymation. E. C. Barnes and H. W. Speicher, in J. Ind. Hyg. < Tox., 24, 10-17 (January, 1942) '`The Deter mination of Formaldehyde in Air," stated that they exposed themselves to 20 ppm for a short length of time. From the discomfort and lachrymation produced, it was their opinion that somewhat lower concentrations would be desirable for continued ex posure. It is generally accepted that exposures should not exceed 10 ppm. Furfural: According to the pro ducer, with reasonably good ventila tion, the health hazard presented by the use of furfural is slight under practically all industrial conditions. Over the 20 years of its industrial use, there has not been a single case of injury to health from industrial ex posures, its low vapor pressure pre sumably maintaining atmospheric concentrations at less than injurious levels under normal industrial condi tions. Gasoline: Philip Drinker, C. P. Yaglou, and M. F. "Warren, in J. Ind. Hyg. < Tox., 25, 225-232 (June, 1943), "The Threshold Toxicity of Gasoline Vapor," concluded "that 0.1 per cent gave the beginning of real effects in our group." The human sub jects used in these experiments com plained only of subjective symptoms such as irritation or headache. R. R. Sayers, A. C. Fieldner, W. P. Yant, and B. G. H. Thomas, in "Experi mental Studies on the Effect of Ethyl Gasoline," Kept, of the U. S. Bureau of Mines (1927), reported that 0.07 to 0.28% gasoline vapor caused dizzi ness. The concentration of 500 ppm is suggested as the maximum so that these subjective symptoms may be avoided. Furthermore, present-cay gasoline contains varying amounts of aromatic hydrocarbons which tend to increase its toxicity. Heptane: Since 1000 ppm was shown to cause slight dizziness in the experimentation carried on by the U. S. Bureau of Mines as given in the Report of Investigations No. 2979 (1929), an allowable limit of 500 ppm is suggested. However, exposures somewhat in excess cz this concentra tion are not considered toxic. Hexar-e: Philip Drinker, C. ?. Yaglou. and M. F. Warren, in J. Ind. Hyg. & Tox., 25, 225-232 (June. 1943) "The Threshold Toxicity of Gasoline Vapc-r," reported on exposure to a petroleum distillate, 90% of which boiled between 107;F and 2S0CF, thus including the hexane ran%*e. Two groups of persons were exposed to concentrations in one case of 1500 ppm and in the other 1400 ppm. Sickness at the stomach, headache, throat irri tation and eye irritation were com plained of, but no one considered the exposure disagreeable or felt unwill ing to work in such atmosphere. Nel son, et al., in J. Ind. Hyg. <* Tox., 25, 2S2 (1943), exposed a group of per sons to 500 ppm of hexane which proved to be quite innocuous. Though higher concentrations were not used, the opinion was that much greater amounts could be tolerated. A maxi mum allowable concentration of 1000 ppm is accordingly suggested. Hydrochloric Acid (Hydrogen Chlo ride): Willard Machle, K. V. Kitzmil'er, E. W. Scott, and J. F. Treon, in J. Ind. Hyg. A Tox., 24, 222-225 (October, 1942), "The Effect of the Inhalation of Hydrogen Chloride," concluded on exposure of animals six hours a day, five days a week for four weeks that the upper limit of safety is about 30 ppm though it is possible that even this concentration would be harmful if daily exposures were con tinued for periods longer than a month. The maximum allowable con centration of 10 ppm is generally accepted. Hydrogen Cyanide: Reference is made by Flury and Zernik in "Schadliche Gase," 1931, to Lehmann-Hess that IS to 36 ppm could be tolerated over a six hour period without appar ent symptoms. A value of 20 ppm is generally accepted as the maximum allowable concentration. Hydrogen Fluoride: E. Ronzani, in Arch./.Hygiene, 70, 217-269 (1909), found no injurious action on animals exposed for 30 days to 3 ppm. K. Roholm, in '`Fluorine Intoxication. A Clinical, Hygiene Study," (Lewis & Company, London, 1937). and "Fluo ride Compounds" Occupation and Health Supplement, International International Labor Office (Septem ber, 1938), reported that r.uorosis of the bones occurred among cryolite workers after prolonged exposure to 2 to 3 ppm. Three ppm has been gen erally accepted as a maximum allow able concentration. Hydrogen Selenitic: H. C. Dudley and J. W. Miller, in Reprint No. 1S55, from. Pub!. Health P.epts.. 52, 1217 (1937), found that animals exposed to six parts per million for 60 minutes all died within 24 days. These work ers, in a subsequent study in J. Ind. Hyg. d: To::.. 23. 470-477 (1541), ``Toxicology of Selenium. VI. Effects o: Subacute Exposures to Hydrogen Seienide," reported that death oc curred in 50% o: animals exposed for eight hours to a concentration of from 0.3 to 1.2 ppm. A concentration oi 1.5 ppm was intolerable to man, producing eye and r.zsal irritation, but .3 ppm caused no such irritation. In view of the great toxicity of this gas. the allowable concentration of 0.1 ppm is suggested with the recommendation that wherever men may be exposed they be under medical observation and information be maintained con cerning exposures. Hydrogen S>d.hde: H. L. Barthel- -my, in J. Ind. Hyg. < Tox., 21 151 (April, 1939), "Ten Years' perience with Industrial Hygien^' Connection with the Manufacture of Viscose Rayon," concluded that with hydrogen sulfide at less than 20 ppni no trouble whatsoever was experi. enced. This value is generally accepted as causing neither poisoning or "eve irritation. " Iodine: Henderson and Haggard "Noxious Gases," 1943, and Flury and* Zernik, "Schadliche Gase," 1931, both quote Matt, Dissertation at Wurzburg 1S89, as authority for 0.1 ppm being the concentration at which "work is not disturbed." The infrequent exn<> sure of iodine vapor hardly justifies much research on this material but added data are needed to substantiate this tentative value of 0.1. Iron Oxide: It has been shown through determination of iron oxide concentrations at many welding op erations that the condition is satis factory where the iron oxide fume is kept below 30 mgs. per cubic meter. Although exposures to iron oxide in excess of this value will not cause poisoning, continued exposure to higher concentrations -may produce a chronic bronchitis. This suggested allowable concentration is given bv Philip Drinker and A. G. Cranch in "Control of Welding Hazards in De fense Industries," Special Bulletin No. 5, U. S. Division of Labor Stand ards (1942). Isophorone: H. F. Smyth, Jr., J. Seaton, and L. Fischer, in J. Ind. Hyg & Tox.. 24, 46-50 (March, 1942), "Re sponse of Guinea Pigs and Rats to Repeated Inhalation of Vapors of Mesityl Oxide and Isophorone," con cluded on the basis of animal experi mentation of 30 eight-hour exposures that no effect whatever results from exposure of 25 ppm of isophorone. Lead: The American Public Health Association Committee on Lead Poi soning--R. A. Kehce, Chairman, J. C. Aub, E. L. Belkr.ap, W. C. Dreessen, G. H. Gehrman. M. H. Kror.enberg, May R. Mayers, and W. ?. Yant--in the 1943 Committee P.epcrt "Occupa tional Lead Exposure and Lead Poi soning" stated that, when the air of workrooms regularly contain no more than 0.15 mgs. per cubic meter, cases of disabling lead intoxication do not occur and cases c: questionable or mild intoxicatic-n are rare. This ecu- elusion is based on such extensive studies as those by the U. 5. Public Health Service in storage battery plants as reported by A. E. Russell. R. ?.. Jones, J. J. Bloomneld. R. H. Britten, and L. R. Thompson in Pub lic Health Bulletin No. 205 C1933), and by W. C- Dreessen. T. I. Edwards, W. H. Reinhart. R. T. Page. S. H. Webster, D. W. Armstrong and R. F- Sayers. Public Health Bulletin No. 262 (1241L ncima7:cxc: R. H. Fiir.r.. P. A. Neal. W. H." Reinhart. ,T. M. Laiiavaile. \V, B. Fulton, and A. E. Doc ley. in Public Health Bulletin No. 347 > :i-4v- "Chronic Manganese- P d-c r i-.g :r. :.r. t.C!'" :~" Mi;!.'' ;h0','.'od uh.lt ...'orhev< exposed to less than SO mgs. ,,er cubic'meter of manganese devel oped no symptoms of poisoning but '.hat workers exposed to more than 90 ^ijs. per cubic meter were found to II- the disease. Since only a small | * of men with limited exposure .eluded in the study, and as the exposure could be readily reduced to *; mgs- per cubic meter, the U. S. Pub- ,:c Health Service has recommended, :g National Institute of Health Bul letin No. 1S2 (1943), "Industrial >Uganese Poisoning" by L. T, Fair- ;;311 and P. A. Neal, that the maximum allowable concentration be tentatively placed at 6 mgs. per cubic meter. ` Magnesium: Philip Drinker, R. M. Thomson, and J. L. Flinn, in J. Ind. #yg., 9, 187 (1927), "Metal Fume fever. III. The Effects of Inhaling Magnesium Oxide Fume," reported on, experimental production of metal fume fever from excessive inhalation 0f this fume. It was considered that exposure to less than 16 mgs. per cubic meter will cause no such mani festation. ' . Mercury: P. A. Neal, R. H. Flinn, T. I. Edwards, W. H. Reinhart, J. W. Hough, J. M. Dallavalle, H. Goldman, tf. Armstrong, A. S. Gray, A. L. Cole man, B. F. Postman, Pub. Health Bull. Mo. 263 (1941), "Mercurialism and Its Control in the Felt Hat Industry," found on the basis of examination of .534 hatters in five representative felt -at factories that no injury to health occurred where the exposure was less 1 mg. per cubic meter. A, jl Oxide: H. F. Smyth, Jr., J. eaton and L. Fisher, in J. Ind. Hyg. ( Tox., 24, 46-50 (March, 1942), "Re- por.se of Guinea Pigs and Rats to Repeated Inhalation of Vapors of Mesityl Oxide and Isophorone," report hat no effect whatever was found vom 50 ppm of mesityl oxide after i eight-hour exposures of all animals. Methanol: R. R. Sayers, W .P. Yant, H. Schrenk, J. Chovnyak, S. J. iarce. F. A. Patty, and J. G. Linn, in S. Bureau of Mines Report of ivestigation No. 3617 <. 1942) , "Meth- .ic! Poisoning. I. Exposure of Dogs 450-500 ppm Methanol Vapor in ir," observed no symptoms or un- ua! behavior among dogs exposed hours daily seven days a week ; :;79 days to 450-500 ppm. It is t-crdir.giy considered that 200 ppm r. be accepted as a maximum allow- ,e concentration. Methyl Aceiaie: Although no ani- r: experimentation work has been yorted or. low concentrations of this vent, work done by Nelson, et ah, iud. Hyg. < To*., 25. 252 < 19431. ethyl, butyl and amyl acetate indi tes that 100 ppm is the highest con- .-.ration which would be satisfactory eight hour exposure from the :t:' :sw of sensory response to the view of the possibility of poi nt'.,, .nrough hydrolysis of this ester bin the body and the conserve:'.: luctsor. M methanol, workers >:- .d to concentrations exceeding the suggested limit should be under med ical observation. Methyl Bromide: D. D. Irish, E. M. Adams, H. C. Spencer, and V. K. Rowe, in J. Ind. Hyg. & To*., 22, 218 230 (June, 1940), "The Response At tending Exposure of Laboratory Ani mals to Vapors of Methyl Bromide," reported that six months' exposure of rats, guinea pigs and monkeys to 33 ppm was without gross symptoms or histopathological changes. However, the rabbits developed paralysis on re peated exposures. With concentra tions dropped to 17 ppm, no abnormal conditions were noted. R. M. Watrous, in Industrial Medicine, 11, 575-579 (December, 1942), "Methyl Bromide --Local and Mild Systemic Toxic Effects," discussed an industrial ex posure where 90 persons were at work at concentrations generally less than 35 ppm and mild systemic symptoms occurred in 33 of these workers. A maximum allowable limit of 20 ppm is suggested.- Workers exposed to or working with methyl bromide should be under medical observation and ex posures checked Quantitatively. Methyl Butavone: H. H. Schrenk, W. P. Yant, and F. A. Patty, in Re print No. 1747 from Pub. Health Repts., 51, 624-631 (May 15, 1936), "Acute Response of Guinea Pigs to Vapors, of Hexanone (Methyl Butyl Ketone)," found that animals ex posed to 1000 ppm for 810 minutes showed but slight or no symptoms although human beings noted a strong odor and developed moderate eye and nasal irritation at this exposure. Arbi trarily placing the maximum allow able limit for prolonged exposure at less than quarter of the amount sug-. gested for acute response, the maxi mum allowable concentration of 200 ppm is suggested. Medical observa tion of workers exposed to vapors at this concentration may result in a more liberal limit. Methyl CeUosolve: H. W. Werner, J. L. Mitchell, J. W. Miller, and W. F. von Oettir.gen. in J. Ind. Hyg. & Tox., 25, 409-414 (November 19, 1943), `Effects of Repeated Exposure of Dogs to Monoalkyl Ethylene Glycol Ether Vapors," reported on findings after exposure of seven hours daily, five cays a week for 12 weeks to a concentration of S00 parts per mil lion ox ethyl cellcsolve. Blood changes are recorded at this concentration. L. Greer.burg, M. R. Mayers, L. J. Goidwater. W. J. 3urke, and S. Moskowitz, in J. Ind. Hyg. < Tox., 20, 134-147 (February. 1&3S), "Health Hazards in the Manufacture of `Fused Collars.' I. Exposure to Ethylene Gly col Monomethy] Ether," reported on workrooms concentrations where poi soning occurred. The ventilation was functioning ineffectively following the poisoning cases but was placed in proper condition when atmospheric analyses were made. The methyl celIcsolve portion of the combined sol vent concentration was then found to vs 25 ppm with ail windows wide open and 76 ppm. with windows partly closed to reptc-sent conditions in cold weather. Though it was concluded by these investigators that the concen tration should be kept below 25 ppm, it would seem, in view of the more favorable conditions under which the analyses were made, that the maxi mum allowable concentration of 100 ppm should be permissible. This sug gested limit is supported by an un published report of tests made by the Chemical Hygiene Fellowship at Mel lon Institute, reported in July, 1945. Methyl Celh$o!ve Acetate: The maximum allowable concentration of 100. ppm is suggested on the basis of an unpublished report of tests made by the Chemical Hygiene Fellowship at Mellon Institute, reported in Julv. 1945. ' " Methyl Chloride: R. R. Sayers, W. P. Yant, B. G. H. Thomas, L. B. Berger, in Pub. Health' Bull. No. 185 (1929), "Physiological Response At tending Exposure to Vapors of Methyl Bromide, Methyl Chloride, Ethyl Bro mide and Ethyl Chloride," found on exposing animals for a period of 800 minutes that from 500 to 1000 ppm caused slight symptoms after several hours exposure. Arbitrarily taking one-fourth of this value for continued exposure, a maximum allowable con centration of 200 ppm is suggested. Workers exposed to concentrations in this vicinity should be under medical observation. Methylcijclohexane: J. F. Treon, W. E. Crutchfield, Jr., and K. V. Kitzmiller, in J. Ind. Hyg. & Tox., 25, 323-347 (October, 1943), "The Physio logical Response of Animals to Cyclo hexane, Methylcyciohexane, and Cer tain Derivatives of these Compounds," concluded that a maximum safe con centration for prolonged exposure of rabbits lies between 1162 and 2886 ppm. A concentration of 1000 ppm is suggested as a maximum allowable limit but if workers are exposed to such a concentration, medical observa tion is recommended until data are obtained on effects of human exposure within this range. Meihylcyclohexcn.ol: In the refer ence cited above for methylcyclohex- ane, the maximum safe concentration for prolonged exposure of rabbits to methy3cyc 3ohexar.oi was found to be slightly below 145 ppm. One hun dred ppm is suggested as allowable, but workers exposed to, such a con centration should be ur.ter medical observation. Meihylcyclokexo.H'jne: The forego ing reference cited for trsthylcyclo- bexane is authority for the conclusion that the maximum safe concentration for prolonged exposure c: rabbits to methyicycichexanor.e lies between 152 and 514 ppm. A maximum allowable concentration of 190 ppm. is suggested but here again medical observation is recommenced where exposures are of this order. Methyl Forr/dc: H. H. Schrenk. IV. P. Yar.t, John Chernyak, and F. A. Patty, ir. Reprir.t No. 1773 from Publ. Health Reports. 51. 1329-1337 (Sep- tember -'.o, 392','). "Acute Response, of Sit rob-, azciic: The U. S. Public v.-as stated that iovO ppm of immtar;.-. Guinea Pigs to Vapors of Methyl For Health Service suggests a maximum caused slight dizziness. Octane i CCn_ Vi. mate," concluded that the maximum exposure .for several hours without serious disturbance lies between 1500 and 2000 ppm. Reducing this concen tration for acute exposure arbitrarily to one-fourth the value, a maximum allowable concentration of 400 ppm is suggested for prolonged exposure. Until information is obtained on re sponse of humans to exposures of this order, workers exposed to such con centrations should be under medical allowable concentration of 5 ppm to serve as a guide. A value of 1 ppm has been used in the past, based pre sumably on this value as listed with out specific reference in Henderson and Haggard, "Noxious Gases," 1927, as a maximum amount that can be inhaled for one hour without serious disturbance. Nitroethane: Willard Machle, E. W. Scott, and Joseph Treon, J. hid. Hyg. & Tox., 22, 315-332 (October, sicered to be somewhat more narcotic than heptane but*to cause substan tially the same physiological reaction Ozone: C. E. Thorp, in Neu-s EdC. tion, American Chemical Society 19 6S6-6S9 (June 25, 1941), "Influence of Nitrogen Oxides on the Toxicity of Ozone," reported that 1 ppm of pure ozone becoming annoying to 257? of exposed persons but even at seven hours a day tor five days did not cause irritation of nose or threat tri: log ovc 4 et (S in tvs su: at 'J th ph observation. Methyl iso-butanone (Hexone) : H. Specht, in Reprint No. 1911 of Pub. Health Reports, 53, 292-300 (Febru ary 25, 193$) '`Acute Response of Guinea Pigs to Inhalation of Methyl 1949), "The Physiological Response of Animals to Some Simple Mononitro. paraffins and to Certain Derivatives of These Compounds," exposed animals to concentrations of as low as 1009 ppm and 500 ppm. At the former Thorp refers to earlier work in -vhic'' oxides of nitrogen are presumably coni taminating the ozone and headaches and sore throats are produced in two hours to three hours at concentrations of 1.0 ppm. - he wc tic co: shi Iso-butyl Ketone," concluded that a concentration below 1000 parts per million is welltclerated by guinea pigs but causes eye and nose irritation in man. Applying the arbitrary rule of reducing this concentration to onefourth where there is prolonged ex posure to the vapor, the maximum allowable limit of 200 ppm is sug gested; Until further data are ob tained on human response, medical concentration, death resulted in some of the animals and no fatalities at the latter concentration. Since no data are given as to the possibility of symp toms or of pathology on long exposure of these animals to 500 ppm, a tenta tive allowable concentration of 200 ppm is suggested. In view of the lack of quantitative 'data on experi ence with persons where nitroethane may be present in industrial atmos Pcntachloronaphthalene: References on these compounds are given under the heading, "Chloronaphthalenes." Pentane: U. S. Bureau of Mines Reports of Investigations No. 2973 (1929) reports that 5000 ppm pro duces no effect after 10 minutes' exposure. Since the allowable con centration of this almost' non-toxic hydrocarbon is properly to be based more on sensory response rather than ab' ge ex; fcio Hi inc on 1 tai bu tin observation is recommended where ex posures may be of this order. , Monochlorobenzene: The maximum pheres, there should be medical ob servation of workers exposed to such concentrations. on systemic poisoning, this concen tration of 5000 ppm is tentatively suggested as allowable. l E. | J. allowable concentration of To ppm is suggested by the U. S. Public Health Service as a guide. Monofiuorotrichlorov,ethane (Freon- \11--Carrene Mo. 2): A. H. Nuckolls, in Underwriters' Laboratories Miscel laneous Hazards Report No. 2375 (No (. vember, 1933), found that animals Nitrogen Oxide: L. W. LaTowsky, E. L. MacQuiddy," and J. P. Tollman, in J. Ind. Hyg. & Tox., 23, 129-133 (April, 1941), "Toxicology of Oxides of Nitrogen. I. Toxic Concentrations," concluded on animal experimentation that the concentration of 30 ppm of NO- on three hour exposure produces Pentanone (Methyl Propancne); \V. P. Yant, F. A. Patty. H. H. Schrenk. in Reprint No. 1739. Pub. Health Re ports, 51, 392-399 (April 3. 1936), "Acute Response of Guinea Pigs to Vapors of Pentanone (Methylpropylketone)," concluded on exposure of animals for 810 minutes that the \ 19 - to * of 4 po I co: f 40 i !0' have occasional tremors and retching movements upon two hours' exposure to 2.2 to 2.57c in air. Consequently a maximum allowable limit of 10,000 ppm is suggested for prolonged ex posure. In view of the lack of infor mation on prolonged exposures on no immediate or delayed harmful effects on guinea pigs and that a concentration of 55 ppm on two to three hour exposure may or may not produce harmful effects on rats and mice but no effect on rabbits, cats and guinea pigs. This and other recent maximum amount for several hours with slight or no symptoms is 1500 ppm. This concentration was found to be very irritating to men even for short exposures. A maximum allow able concentration of 400 ppm for pro longed exposure- is arbitrarily taken 1 5a. } su ba tic th O" * fc humans to this refrigerant, there should be medical observation if ex posures approach this value. data support the American Standard of 25 ppm. Nitroglycerine: The U. S. Public at one-fourth of the suggested limit for several hours exposure. With lack of quantitative information on human qw Mcmoniiroicluene: The maximum Health Sendee have found no systemic subjects at these concentrations, there allowable concentration for this com pound is considered by the U. S. Pub lic Health Service to be similar to that of nitrobenzene for which a value of 5 ppm is suggested as a guide. Naphtha (Coal Tar): A maximum allowable concentration c: 100 to 200 ppm is suggested, dependent upon the relative proportions of benzene, tolu ene and xylene present. If the boiling effects occur even at exposures of 10 ppm, but after absence of exposure for as little as a 40 hour period over a week-end, severe headaches occur on being first exposed to as little as 0.5 ppm for a brief period. Skin absorp tion is a major source of intake where there is contact with nitroglycerine. .Virroj-;f/!Cj;c: In the reference quoted ::r "Nitroethane." Willard should be medical observation of workers exposed to vapor in the vi cinity of this limit. Phosgene: U. S. Bureau of Mines, Technical Paper No. 24S (1921), "Gas Masks for Gases Met in Fighting Fires." by A. C. Fieldner. S. H. Katz, and S. P. Kinne, referred to ra wer!: of the American College Experi ment Staticr. Chemical Warfare Serv B L. F la 3 rr. H d. P point range of a solvent naphtha ob Machle. E. W. Scott, and Joseph Treon ice, as authority for considering S rrm tained from coal tar or .from by found that no deaths have occurred on as the maximum concentration a'.icw- ; s. a' product coke distillation includes any daily six hour exposure for a total of able for prolonged exposure. Flury appreciable percentage between the 140 hours to 500 ppm. A maximum and Zernik. "Schadiiche Case." 1931. boiling point of benzene and toluene, allowable concentration of 200 ppm is gave in a table without specific refer ! r.o mere than 11*0 ppm should be per suggested in view of lack of specific ence to original work that the per mitted; but i: the coiling point of the data on effect of nitre-methane on per. ceptible concentration was between 1.4 major portion cf this naphtha is above sons under industrial exposures. and 2.$ ppm. _ that of toluene, then 200 ppm may be considered allowable. References are giver, under the respective chem ical compounds. A'aphtha (Pci'-cdc.on : A concen Where exposures approach the sug gested allowable concentration, there should be medical observation of such exposed persons. Octane: A suggested allowable limit Phosphorus Trichloride: Bu:; ag. :r. Arch. /. Hyg.. 49, 307 11904). reported on the basis of animal experimentation that 0.7 ppm caused only slight irrita tion. ., ! : t c l r e tration of 500 ppm is suggested on the basis of the discussion and references included under gasoline. of 500 ppm is based on the U. S. Bu reau of Mines Report of Investiga tions No. 2979 (1929), in which it isc'-Prcpoiol (iso-Propw! iuo'^o.^: Although brief exposures to annuais have been conducted at high cercen- i c. t 1 U. No. i i iNOL'STR1AL MEDICINE Pcgc 0 4 ) :ions, trtere has been no toxico- cal work done on low exposures c prolonged periods of time. Nelson, :\h in J. Ind. Hyg. & Tox., 25, 282, Her, 1943), reported that mild It. if the eyes, nose and throat s caused at 400 ppm among human jeets experimentally but that even ?00 ppin the effects were not severe ugh the majority declare the atmos- re unsuitable. Iso-propyl alcohol is -.ewhat more toxic than ethyl alco- . but it is believed that no difficulty uld be experienced at cor.centra-' its of 400 ppm. Workers exposed to .ventrarior.* approaching this value uld be under medical observation. propyl Acetate: A maximum allow- le concentration of 200 ppm is sug- ded, not that somewhat higher pesures are toxic but to avoid irritan. Although Nelson, et al. in J. Ind. <<7. & Tox., 25, 2S2 (1943),' did not dude this ester among the solvents which sensory responses were ob- ned, on analogy with ethyl and *yl acetates, it is considered that ' suggested limit is in order. :so-Propyl 'Ether: Willard Machle, W. Scott, and Joseph Treon, in Ind. Hyg. ii Tox.. 21, 72-95 (March, 39), ``The Physiological Response Isopropyl Ether and to a Mixture Isopropyl Ether and Gasoline," re- vted on exposure of animals for 20 o-hour and three-hour periods to ncentrations down to 3000 ppm and 00yT'--m No noticeable effect fcl,va exposure. The toxicity of iprt^yi ether and gasoline were conlered to be closely parallel on the sis of these animal experimer.tams. Although it appears possible at exposures may be appreciably eater than the suggested limit he re toxic action occurs, any increase this vaiue should be based on antitative results of exposures to vksrs. Pna'on (Radium Erue.ration) : An .isorv committee to the National mean of Standards, composed of F. Curtiss. R. D. Evans, G. Failla. iderick 3. Flinr.. Harrison S. Mart- :d. J. Z. Paul. J. S. Rogers, C. S. .-pher.scn ar.d C-. T. Taylor, reccm- .nded ir. National Bur. of Stand, .ndbook H 27 (1941>. "Safe nan ny Radioactive Luminous Com unis." that the radon concentration the a:m.;s;;here of workroom* :uii no: exceed curio per liter, d that the whole-body exposure of : worker to gamma radiation should : exceed 0.1 roentgen per working y. These figures, noted as being icercing to present knowledge" in -11. continue to be accepted in 1945. {.Hydrogen riiimonice) : :ck. Guttmar.n, and Gergell, Bcr. soft. '"cm. Ges.. 37. SS3 (1904). re- :t At 100 parts per million on ; : for 20 minutes causes death tev a few days. The maximum allow- le concentration of 10 ppm is tenta- e'v suggested. Wherever there may possibility of exposure to* stibir.e. rkers should be under medical ob- vation. Stoddard Solvent: A maximum al lowable concentration of 500 ppm is suggested on the basis of the discus sion on gasoline. Although the higher boiling constituents which are in cluded in Stoddard Solvent are some what more toxic than those included in gasoline, it is believed that expo sures could be considerably greater than the suggested concentration with out causing toxic effect. The limit is set up largely to avoid subjective symptoms. Nelson, et al., in J. Ind. Hyg. & Tox., 25, 2S2 (1943), reportthat experimental human subjects complain of no marked effects of Stod dard Solvent vapor up to 400 ppm and conclude that the exposure can exceed this amount somewhat and still be considered a satisfactory atmos phere. Styrene Monomer: H. C. Spencer, D. D. Irish, E. M. Adams, and V. K. Rowe, in J. Ind. Hyg. & Tox., 24, 295-301 (1942), "The Response of Laboratory Animals to Monomeric Styrene," concluded on the' basis of lack of effect on animals exposed for seven hours a day over a period of six months to 650 ppm that this con centration would probably produce no serious disturbances in man but is definitely irritating to the eyes and nose. It was considered that 400 ppm which Spencer, et al., considered as giving a disagreeable odor but not producing appreciable eye or nose irritation, could be suggested tenta tively as a permissible limit for repeated exposures. This has been ac cepted as an "American War Stand ard." Experience has already indi cated that this concentration causes sufficient irritation under actual work ing conditions to revise this Standard downward. Until broader experience is available, it is suggested that con centrations be not allowed to exceed half the tentative value of 400 ppm. Sulfur Chloride: Adler-Herzmark, in Zcn.tr. Gexcerbehyg. u. Unfaiiveri-.iii., 6, 97 (1929), reported that cats tolerated 12 parts per million for 15 minutes without death. At 4$ ppm for 15 minutes, death occurred after sev eral days. A maximum allowable con centration of 1 ppm is suggested as a tentative'' limit. Sulfur Dioxide: Fieldner and Katz, in Enc. S: Mining 107. 623 i1909), considered 10 ppm as the highest con centration tolerable for prolonged exposure. Flury and Zerr.ik ir. "Sehadiiche Gase." 1931. include an unidenti fied reference to Lehmar.n-Kess in which a concentration o: 3 to 12 ppm is suggested a* permissible for several hours' exposure. Sulfuric Acid: The individual sus ceptibility to irritation by sulphuric acid differs widely among individuals, much higher concentrations being tol erated by workers habitually exposed. Flury and Zerr.ik. "Schadliche Cased' 1931. includes one reference indicating 40 milligram* per cubic meter and ever, two to three times this concen tration as being non-injurious or hardly injurious and another refer- ence indicating that 0.5 to 2 milli grams per cubic meter caused slight trouble with 3 to 4 milligrams per cubic meter causing definite trouble. J. H. Sterner, in Industrial Medi cine, 12, 514-518 (August, 1943), "Determining Margins of Safety-- Criteria for - Defining a `Harmful' Exposure," lists 5.0 milligrams per cubic meter in his well considered table of maximum allowable concen trations. . 1,1,2,2-Tetrachloroetkane: On the basis of severe poisoning of workers in industry resulting in a number of deaths together with animal experi mentation showing it to cause nar cosis with smaller amounts than are necessary for carbon tetrachloride, a maximum allowable concentration of 10 ppm has been suggested for tetra- chloroethane. Such cases are cited by A. Hamilton in "Industrial Toxicol ogy/' PP- 212, et seq., Harper and Co., 1934, and more recently by H. A. Coyer in Industrial Medicine, 13, 230-233 (March, 1944). Medical ob servation of persons exposed to known concentrations of tetrachloroethane under industrial conditions are neces sary to substantiate this tentative maximum allowable concentration. Tetrachloroetkylene: C. P. Carpen ter, in J. Ind. Hyg. & Tox., 19, 323 336, (September, 1937), "The Chronic Toxicity of Tetrachloroethylene," re ported on animal exposure to low con centrations for periods up to 1200 hours and oh exposures of humans to concentrations of.500 ppm and above. No injurious exposure was observed at 70 ppm but at 230 ppm some of the animals showed effects of the solvent on kidneys, spleen and liver though there were no signs of progressive injury to the liver. This author con cluded that on the basis of the find-' ir.gs, a concentration somewhere be tween 100 and 500 ppm is considered safe for daily exposure not in excess of 40 hours a week. Until more evi dence i* available on human exposures under industrial conditions, workers exposed to concentrations in the vicin ity of the suggested allowable limit of 200 ppm should be under medical ob servation. Tcii'rriubi: H. H. Steinberg, S. C. Massari. A. C. Miner, and R. Rink, in J. Ind. Hyg. & Tor.., 24. 133-192 (Sep tember. 1542), "Industrial Exposure :o Tellurium.: Atmospheric Studies ar.d Clinical Evaluation," reported on industrial exposure of worker* to tellurium and tellurium oxide fume together with clinical and laboratory findings. At exposures ranging for the most part from. 0.01 to 0.1 milli grams per cubic meter, no evidence of tellurium as such was found but a social stigma resulted from the presence of garlic odor of the breath and ci the sweat. On the basis of these finding*, the maximum allow able c ncentration of 0.01 milligrams per cubic meter is suggested, not that concentration* 10 time* this limit will cause poisoning but to avoid the dev--:, opm.er.; of the exceedingly distasteful  r'uge !K6 1N DUST RIAL MEDICI X K A over,iher. i.045 garlic odor eminated by the exposed person. > Teiryl: The U. S. Public Health Service stales, in "Manual of Indus trial Hygiene" (W. B. Saunders Com pany, 1943) .that "no specific infor mation is available but 1.5 milligrams per cubic meter is believed to present no health hazard." . Toluene (Toluol) : W. F. von Oettingen, P. A. Neal, D. D. Donahue, J. L. Svirbely, H. D. Baernstein, A. R. Monaco, P. J. Valaer, ar.d J. L. Mit` chell, in Pub. Health Bull. No. 279, (1942) "The Toxicity and Potential . Dangers of Toluene, with Special Pveference to Its Maximal Permissible Concentration," concluded that it ap pears, as far as toxicity is concerned, the maximal permissible concentration . for toluene in air for eight hours ex posure daily is 200 ppm. Since the - exposure causes slight but definite . impairment of coordination and reac tion time, it was suggested that where ' the occupation may cause specific ac . cident hazards, this concentration might prove to be too high. Trichloroethylene: Josech Seifter, in J. Ind. Hyg. & Tox., 25, 250-252 (September, 1944), "Liver Injury in Dogs Exposed to Trichloroethylene," reported that an exposure of 500 to 750 ppm four to six hours daily, five days a week for eight weeks resulted ` in liver injury to experimental dogs. There is no published animal experi mentation at concentrations lower \ than this value. It has'been rather ~ generally accepted that a concentra tion of 200 ppm can be tolerated with out injury to health. K. M. Morse and Louis Goldberg, in Indust. Hyg. Sup plement, Industrial Medicine, 12, 706-713 (October, 1943), "Chlorinated Solvent Exposures at Degreasing Op erations," reported that lS'yc of some 336 vapor degreasing tanks provided with condensers exposed the operators to more than 200 ppm. Although this paper does not include clinical find ings on exposed workers, the fact that no reference is made to cases of poisoning among operators of these tanks would indicate that 200 ppm is not greatly out of line as the maxi mum allowable concentration. There is evidence, however, that a concen tration of this order may cause diffi culty among a sufficient number of operators to require that it be re duced. Morse and Goldberg, cited above, report that some men will com plain of headaches, r.ausea and diz ziness ever, at concentrations of 100 pom. Consequently, it is recom mended that, until further clinical evidence is available concerning pos sible injury at concentrations lower than 200 ppm exposures be net al lowed to exceed half the value sug gested as the maximum allowable con centration. Tr:r;: lorouaok thclcnc : This com pound was discussed under the head ing "Chloror.aphthaiene." T.'yritro'oli'CnC (TN'T): The U. S. Public Health Service recommends that 1.5 milligrams per cubic meter be used as a guide. W. F. von Got tingen, D. D. Donahue, R. K. Snyder, and A. R. Monaco in Public Health Bull. No. 2S5 (1944), "Experimental Studies on the Toxicity and Potential Dangers of Trinitrotoluene (TNT). IY. Toxicity of TNT for Dogs with Inhalation of Its* Fumes." stated that an attempt was made to determine the effect of various concentrations of TNT vapor on dogs but it was found very difficult if not impossible to volatilize TNT in sufficient quantities to produce definite systemic and toxic effects on them. Experience has shown that where there is exposure to TNT dust, fume' or vapor, workers should be under medical observation. Toluidine: Henderson and Haggard, "Noxious Gases," 1927, include a table, without specific reference to original work, which states that slight symptoms after several hours expo sure are caused by concentrations in the range of 7 to 26 ppm. This same table refers to similar response being caused by a range of 7 to 53 parts per million of aniiin. Since a broader experience with aniline indicates that 5 ppm can be considered as a maxi mum allowable limit, a similar concen tration is suggested for toluidine. In view of the lack of specific data on prolonged exposure, persons subjected to toluidine should be under medical observation. . Turpentine: H. F. Smyth and H. F. Smyth, Jr., in J. I?id. Hyg., 10, 261 (1323), "Inhalation Experiments with Lacquer Solvents," found that con tinued inhalation of 750 ppm caused no injury to experimental animals. K. B. Lehmann, in Arch. f. Hyg., 83 239 (1914), "Comparative Research on the Toxicity of Turpentine," re ported that inhalation by himself and his assistant of concentrations ox 750 to 1000 ppm for several hours caused eye irritation, headache, dizziness and nausea. Nelson, et al., in J. Ind. Hyg. Tox., 25, 232 (1943), found eye and nose irritation at 175 ppm and throat irritation at 125 ppm. A maximum allowable concentration of 100 ppm has been suggested not that an ap preciably higher concentration will cause poisoning but to avoid irritation. Vinyl Chloride: F. A. Patty, W. ?. Yant, and C. P. Waite, in Reprint No. 1405 from Pub. Health Rents.. -15. 1963-1371 (August 22, 1930), "Acute Response of Guinea Pigs to Vapor of Vinyl Chloride." found on exposure of animals to periods as long as 50; minutes that the maximum amount for several hours without serious dis turbance was -5000 ppm. Arbitrarily using approximately a fourth o: this value as the maximum allowable con centration for proler.gc-d exposure, a value of 100 ppm has been suggested. Ir. view of the lack of anim.ai experi mentation over a long period and of -industrial exposure to known concen trations, there should be medical ob servation of exposed workers where concentrations may be in the vicinity of the suggested limit. X-ray: Although the International X-ray and Radium Protection Com mission recommended in 1937 that about 0.2 roentgen per day or on* roentgen per week could be tolerated by a person in normal health as pub lished in Radiology, 30, 511 (April 193S), an able and representative committee under the chairmanship.0f George Singer, National Bureau of Standards, set up the American War Standard of 0.1 roentgen as the permissible daily dose under th= American Standards Association pro'cedure, May, 1945. This maximum allowable limit is now general-,- accepted. ` Xylene (Xylol): On the basis of analogy of the action of xyler.e with that of toluene, a maximum allowable concentration of 200 ppm is suggested" Xylene vapor is somewhat more irri tating to the eyes than that of toluene and it is probable that a somewhat lower limit of exposures may be re quired to permit comfort of the worker. Zinc: Philip Drinker, R. M. Thom son, and J. L. Finn, in J. Ind. Hyg. Tor., 9, 331-345 (August, 1927), "Metal Fume Fever: IV. Threshold Doses of Zinc Oxide," found that con centrations of 14 milligrams of zinc oxide per cubic meter (measured as zinc) produced no reaction on the average subject after an exposure of eight hours. They add that if the dosage of zinc oxide is insufficient to cause fever, there is no evidence that daily inhalation of the fumes does chronic damage. D. Mark Hegsted, J. M. McKibbin, and' C. K. Drinker, in Supplement No. 179 to Pub. Health Repts., (1945), "The Biological, Hy gienic, and Medical Properties of Zinc and Zinc Compounds," include the statement that "15 mg. zinc c-xide per cubic meter of air are considered as representing a safe maximum, there being no possibility of barm from pro longed exposure at this level of con centration in the air breathed." Georgia Section Organized he Georgia Section of the Amer Tican Industrial Hygiene Associa tion was formally organized at meeting held in Atlanta on June 1. 1C-45. Attending the .meeting --ere representatives from industry, govern mental agencies and professional groups concerned with industrial hy giene in this state. Prior to the meet ing. a trip was made through the Marietta Plant of the Beil Aircraft Corporation where the meeting was a The following centers were elected: President, x. v. hendricks. Georgia Department of Public Health; Vice President, L. brown, m.d., Physician. Bell Aircraft Corporation; SecretaryTreasurer, C. G. bender, Beil Aireraft Corporatior.. L. M. petriz. Director of the Industrial Hygiene Division cf the Georgia Department of Public Health, introduced the principal speaker of the evening, major t. r. thomas of the United States Public Health Service.