Document ZBbKB0ypbEpgoND6rVZnn6JYV

& 2^ GrZC&G-E TLVs Threshold Limit Values for Chemical Substances and Physical Agents in the Workroom Environment with Intended Changes for 1977 C j?ep',k *j `t a) l' '' J 5 /f*l St>Ls f s*r*r rs L > h* Qf/i,i (Zs- r/ri- / /? J H t. fit 2 J.. SC 16286 LAA/I025089 Copyright 1977 by American Conference of Govern mental Industrial Hygienists. The American Conference of Governmental Industrial Hygienists will welcome requests for permission to re publish or reprint these Threshold Limit Values. Re quests for such permission should be directed to the Secretary-Treasurer, P.O. Box 1937, Cincinnati, Ohio 45201. PRICE EACH 1-49.............. 50-199.......... 200-999....... 1000-4999... 5000 or more $1.50 1.25 1.10 .75 .65 Documentation of the Threshold Limit Values for Sub stances in Workroom Air* A separate companion piece to the Chemical TLVs is issued by ACGIH under this title. This publication gives the pertinent scientific information and data with reference to literature sources that were used to base each limit. Each documentation also con tains a statement defining the type of response against which the limit is safeguarding the worker. For a better understanding of the TLVs it is essential that the Docu mentation be consulted when the TLVs are being used. Information concerning the availability of copies of the Documentation of the Threshold Limit Values for Substances in Workroom Air should be directed to the Secretary-Treasurer, ACGIH. TLVs Threshold Limit Values for Chemical Substances in Workroom Air Adopted by ACGIH for 1977 SC 16287 LAM025090 t TABLE OF CONTENTS 1977 TLV AIRBORNE CONTAMINANTS COMMITTEE i Hervey B. Elkins, Ph.D., Chairman Charles E. Adkins Hector P. Blejer, M.D. Paul E. Caplan, P.E., M.P.H. Paul Gross, M.D. John W. Knauber, M.P.H. Jesse Lieberman, P.E. Trent R. Lewis, Ph.D. Keith R. Long, Ph.D. FrederickT. McDermott, Ph.D. Floyd A. Madsen Col. Walter W. Melvin, Jr., M.D. Leonard D. Pagnotto, Secretary Meier Schneider, P.E., C.I.H. \ Herbert E.Stokinger, Ph.D. William D. Wagner Ralph C. Wands David H. Wegman, M.D. Chemical Substances Page Preface........................................................................ Threshold Limit Values and Short Term Exposure Limits...................................................................... Radioactivity................................................ Mineral Dusts............................................................. Nuisance Particulates................................................. Notice of Intended Changes....................................... Appendices A. Occupational Carcinogens............................... B. Substances of Variable Composition............. C. Mixtures: Calculation of TLVs........................ 0. Excursions Time-Weighted Average.............................. Peak Concentrations................................... E. Nuisance Particulates...................................... F. Asphyxiants..................................................... G. Conversion of Particle Count to Mass........... 2 9 31 32 33 34 36 43 45 50 51 52 52 53 Physical Agents WJW W WHt'f l Z. * ;? - W"W W W IV !* CONSULTANTS E. Mastromatteo, M.D. Preface........................................................................ 57 Threshold Limit Values Heat Stress............................................................. 58 James F. Morgan Marshall Steinberg, Ph. D. Appendix G. Heat Stress........................................... 59 Ionizing Radiation.................................................. 66 1 Theodore R. Torkelson, Sc.D. Lasers..................................................................... 66 ii i i Mitchell R. Zavon, M.D. Any comments or questions regarding these limits should be addressed to: Microwaves............................................................ Noise....................................................................... Impulsive or Impact Noise.................................... Ultraviolet Radiation................................................ 81 81 83 85 Secretary-Treasurer Notice of I ntended Changes....................................... 88 American Conference of Governmental Notice of Intent: Industrial Hygienists Establish TLV for Light.......................................... 90 P.0. Box 1937 Cincinnati OH 45201: (513)825-0312 Airborne Upper Sonic Acoustic Radiation............. 93 Agents Proposed for Study................................... 94 BjBt BWWffWH '-Wl SC 16288 j._________ LAM025091 rw w nw if M '. f PREFACE CHEMICAL CONTAMINANTS limit. (2) TWA-TLV Excursion Factors listed in Appendix D. (3) Pennsylvania Short-Term Limits for Exposure to Airborne Contaminants (Penna. Dept, of Hlth., Chapter 4, Art. 432, Rev. Jan. 25.1968). (4) OSHA Occupation Threshold limit values refer to airborne concentra al Safety and Health Standards, Fed. Reg. Vol. 36. No. tions of substances and represent conditions under 105, May 29,1971. The TWA-STEL should not be used ;i which it is believed that nearly all workers may be repea as engineering design criterion or considered as an tedly exposed day after day without adverse effect. Be emergency exposure level (EEL). f cause of wide variation in individual susceptibility, how c) Threshold Limit Value-Ceiling (TLV-C) -- the con i ever, a small percentage of workers may experience centration that should not be exceeded even instantan discomfort from some substances at concentrations at eously. or below the threshold limit; a smaller percentage may For some substances, e.g., irritant gases, only one be affected more seriously by aggravation of a pre-exist category, the TLV-Ceiling, may be relevant. For other i ing condition or by development of an occupational ill substances, either two or three categories may be rele i ness. Tests are available (J. Occup. Med. 15; 564, 1973; vant, depending upon their physiologic action. It is im portant to observe that if any one of these three TLVs is Ann. N.Y. Acad. Sci., 151, Art. 2: 968.1968) that may exceeded, a potential hazard from that substance is pre be used to detect those individuals hypersusceptible to a sumed to exist. variety of industrial chemicals (respiratory irritants, he The TLV-TWA should be used as guides in the con molytic chemicals, organic isocyanates, carbon disul trol of health hazards and should not be used as fine fide). lines between safe and dangerous concentrations. i i Three categories of Threshold Limit Values (TLVs) are specified herein, as follows; Time-weighted averages permit excursions above the limit provided they are compensated by equivalent ex a) Threshold Limit Value-Time Weighted Average cursions below the limit during the workday. In some (TLV-TWA) -- the time-weighted average concentration instances it may be permissible to calculate the average for a normal 8-hour workday or 40-hour workweek, to concentration for a workweek rather than for a workday. which nearly all workers may be repeatedly exposed, day after day, without adverse effect. The degree of permissible excursion is related to the magnitude of the threshold limit value of a particular b) Threshold Limit Value-Short Term Exposure Limit substance as given in Appendix D. The relationship be (TLV-STEL) -- the maximal concentration to which tween threshold limit and permissible excursion is a rule workers can be exposed for a period up to 15 minutes of thumb and in certain cases may not apply. The continuously without suffering from 1) irritation, 2) amount by which threshold limits may be exceeded for i chronic or irreversible tissue change, or 3) narcosis of short periods without injury to health depends upon a I sufficient degree to increase accident proneness, impair number of factors such as the nature of the contamin self-rescue, or materially reduce work efficiency, provid ant, whether very high concentrations -- even for short ! ed that no more than four excursions per day are permit periods -- produce acute poisoning, whether the effects S ted, with at least 60 minutes between exposure periods, are cumulative, the frequemy with which high concen i and provided that the daily TLV-TWA also is not exceed trations occur, and the duration of such periods. All-fac t d ed. The STEL should be considered a maximal allowable concentration, or absolute ceiling, not to be exceeded at any time during the 15-minute excursion period. STELs tors must be taken into consideration in arriving at a decision as to whether a hazardous condition exists. Threshold limits are based on the best available infor are based on one or more of the following criteria: (1) mation from industrial experience, from experimental % Adopted TLVs including those with a "C" or "ceiling" human and animal studies, and, when possible, from a i. r2 3 j j. SC 16289 i'rr^aw w B`xy|.i ^ LAM025092 combination of the three. The basis on which the values are established may differ from substance to substance; protection against impairment of health may be a guid ing factor for some, whereas reasonable freedom from irritation, narcosis, nuisance or other forms of stress may form the basis for others. The amount and nature of the information available for establishing a TLV varies from substance to sub stance; consequently, the precision of the estimated TLV is also subject to variation and the latest Documentation should be consulted in order to assess the extent of the data available for a given substance. The committee holds to the opinion that limits based on physical irritation should be considered no less bind ing than those based on physical impairment. There is increasing evidence that physical irritation may initiate, promote or accelerate physical impairment through in teraction with other chemical or biologic agents. In spite of the fact that serious injury is not believed likely as a result of exposure to the threshold limit con centrations, the best practice is to maintain concentra tions of all atmospheric contaminants as low as is prac tical. These limits are intended for use in the practice of industrial hygiene and should be interpreted and applied only by a person trained in this discipline. They are not Intended for use, or for modification for use. (1) as a relative index of hazard or toxicity, (2) in the evaluation or control of community air pollution nuisances, (3) in estimating the toxic potential of continuous, uninterrupt ed exposures or other extended work periods, (4) as proof or disproof of an existing disease or physical con dition, or (5) for adoption by countries whose working conditions differ from those in the United States of America and where substances and processes differ. Ceiling vs Time-Weighted Average Limits. Although the time-weighted average concentration provides the most satisfactory, practical way of monitoring airborne agents for compliance with the limits, there are certain substances for which it is inappropriate. In the latter group are substances which are predominantly fast act ing and whose threshold limit is more appropriately based on this particular response. Substances with this 4 type of response are best controlled by a ceiling "C" limit that should not be exceeded. It is implicit in these definitions that the manner of sampling to determine noncompliance with the limits for each group must differ, a single brief sample, that is applicable to a "C" limit, is not appropriate to the time-weighted limit; here, a sufficient number of samples are needed to permit a time-weighted average concentration throughout a com plete cycle of operations or throughout the work shift. Whereas the ceiling limit places a definite boundary which concentrations should not be permitted to exceed, the time-weighted average limit requires an explicit limit to the excursions that are permissible above the listed values. The magnitude of these excursions may be pegged to the magnitude of the threshold limit by an appropriate factor shown in Appendix 0. It should be noted that the same factors are used by the Committee in determining the magnitude of the value of the STELs, or whether to include or exclude a substance for a "C" listing. "Skin" Notation. Listed substances followed by the designation "Skin" refer to the potenfial contribution to the overall exposure by the cutaneous route including mucous membranes and eye, either by airborne, or more particularly, by direct contact with the substance. Vehicles can alter skin absorption. This attention-calling designation is intended to suggest appropriate measures for the prevention of cutaneous absorption so that the threshold limit is not invalidated. Mixtures. Special consideration should be given also to the application of the TLVs in assessing the health hazards which may be associated with exposure to mix tures of two or more substances. A brief discussion of basic considerations involved in developing threshold limit values for mixtures, and methods for their develop ment, amplified by specific examples are given in Ap pendix C. Nuisance Particulates. In contrast to fibrogenic dusts which cause scar tissue to be formed in lungs when in haled in excessive amounts, so-called "nuisance" dusts have a long history of little adverse effect on lungs and do not produce significant organic disease or toxic effect when exposures are kept under reasonable control. The 5 Sc 1s29q LAM025093 nuisance dusts have also been called (biologically) "inert" dusts, but the latter term is inappropriate to the extent that there is no dust which does not evoke some cellular response in the lung when inhaled in sufficient amount. However, the lung-tissue reaction caused by in halation of nuisance dusts has the following characteris tics: (1) The architecture of the air spaces remains in tact. (2) Collagen (scar tissue) is not formed to a significant extent. (3) The tissue reaction is potentially reversible. Excessive concentrations of nuisance dusts in the workroom air may seriously reduce visibility, may cause unpleasant deposits in the eyes, ears and nasal pas sages (Portland Cement dust), or cause injury to the skin or mucous membranes by chemical or mechanical action per se or by the rigorous skin cleansing proce dures necessary for their removal. A threshold limit of 10 mg/m3, or 30 mppcf, of total dust < 1% quartz is recommended for substances in these categories and for which no specific threshold limits have been assigned. This limit, for a normal work day, does not apply to brief exposures at higher concen trations. Neither does it apply to those substances which may cause physiologic impairment at lower concentra tions but for which a threshold limit has not yet been adopted. Some nuisance particulates are given in Appen dix E. Sbnple Asphyxiants -- "Inert' Gases or Vapors. A number of gases and vapors, when present in high con centrations in air, act primarily as simple asphyxiants without other significant physiologic effects. A TLV may not be recommended for each simple asphyxiant be cause the limiting factor is the available oxygen. The minimal oxygen content should be 18 percent by volume under normal atmospheric pressure (equivalent to a par tial pressure, p02 of 135 mm Hg). Atmospheres deficient in 02 do not provide adequate warning and most simple asphyxiants are odorless. Several simple asphyxiants present an explosion hazard. Account should be taken of this factor in limiting the concentration of the asphyx iant. Specific examples are listed in Appendix F. Physical Factors. It is recognized that such physical factors as heat, ultraviolet and ionizing radiation, humid- 6 tty, abnormal pressure (altitude) and the like may place added stress on the body so that the effects from expo sure at a threshold limit may be altered. Most of these stresses act adversely to increase the toxic response of a substance. Although most threshold limits have built-in safety factors to guard against adverse effects to moder ate deviations from normal environments, the safety fac tors of most substances are not of such a magnitude as to take care of gross deviations. For example, continu ous work at temperatures above 90"?, or overtime ex tending the workweek more than 25%, might be consid ered gross deviations. In such instances judgment must be exercised in the proper adjustments of the Threshold Limit Values. Biologic Limit Values (BLVs). Other means exist and may be necessary for monitoring worker exposure other than reliance on the Threshold Limit Values for industrial air, namely, the Biologic Limit Values. These values rep resent limiting amounts of substances (or their effects) to which the worker may be exposed without hazard to health or well-being as determined in his tissues and fluids or in his exhaled breath. The biologic measure ments on which the BLVs are based can furnish two kinds of information useful in the control of worker ex posure: (1) measure of the individual worker's over-all exposure; (2) measure of the worker's individual and characteristic response. Measurements of response fur nish a superior estimate of the physiologic status of the worker, and may be made of (a) changes in amount of some critical biochemical constituent, (b) changes in ac tivity of a critical enzyme, (c) changes in some physiolo gic function. Measurement of exposure may be made by (1) determining in blood, urine, hair, nails, in body tis sues and fluids, the amount of substance to which the worker was exposed; (2) determination of the amount of the metabolite(s) of the substance in tissues and fluids; (3) determination of the amount of the substance in the exhaled breath. The biologic limits may be used as an adjunct to the TLVs for air, or in place of them. The BLVs, and their associated procedures for determining compliance with them, should thus be regarded as an effective means of providing health surveillance of the worker. 7 bi ii W EWPWWMI^WIHIjW WW VTW W IBHU uiwhh p|i|j gi . SC 16291 if '- J V ... j LAM025094 Unlisted Substances. Many substances present or handled in industrial processes do not appear on the TLV list. In a number of instances the material is rarely present as a particulate, vapor or other airborne con taminant, and a TLV is not necessary. In other cases sufficient information to warrant development of a TLV, even on a tentative basis, is not available to the Commit tee. Other substances, of low toxicity, could be included in Appendix E pertaining to nuisance particulates. This list (as well as Appendix F) is not meant to be all inclu sive: the substances serve only as examples. In addition there are some substances of not incon siderable toxicity, which have been omitted primarily be cause only a limited number of workers (e.g., employ ees of a single plant) are known to have potential exposure to possibly harmful concentrations. "Notice of Intent." At the beginning of each year, proposed actions of the Committee for the forthcoming year are issued in the form of a "Notice of Intended Changes." This Notice provides not only an opportunity for comment, but solicits suggestions of substances to be added to the list. The suggestions should be accom panied by substantiating evidence. The list of Intended Changes follows the Adopted Values in the TLV booklet. Legal Status. By publication in the Federal Register (Vol. 36, No. 105, May 29, 1971) the Threshold Limit Values for 1968 are now official federal standards for industrial air. Reprint Permission. This publication may be reprint ed provided that written permission is obtained from the Secretary-Treasurer of the Conference and that it be published in its entirety. 8 Substance Abate............................. Acetaldehyde................. Acetic acid..................... C Acetic anhydride............ Acetone......................... Acetonitrile..................... Acetylene........ ............... Acetylene dichloride, see 1,2-Dichloroethylene. Acetylene tetrabromide... Acrolein......................... Acrylamide -- Skin........ Acrylonitrile -- Skin....... Aldrin --Skin................ Ally! alcohol -- Skin..... Allyrl chloride.................. Ally! gfycidyl ether (AGE) --Skin............ Allyl propyl disulfide....... Alunduni (Al203)............ 4-Aminodiphenyi -- Skin 2-Aminoethanol, see Ethanolamine............. 2-Aminopyridine............ Ammonia....................... Ammonium chloride-fume............ Ammonium sulfamate (Ammate).................. n-Amyl acetate.............. sec-Amyl acetate............ Aniline -- Skin.............. Anisidine (o-. p-isomers) -- Skin .... * Antimony & Compounds (as Sb)...................... ANTU (a-Naphthyl thiourea)................... ADOPTED VALUES TWA ppm' mg/m3*' __ 100 10 5 1,000 40 F 10 180 25 20 2,400 70 -- 200 790 1 14 0.1 0.25 -- 0.3 20 45 -- 0.25 25 13 5 22 2 12 __ E -- Alb 36 0.5 2 25 18 -- 10 -- 10 100 525 125 650 5 19 0.1 0.5 -- (0.5) -- 0.3 TENTATIVE VALUES STEL ppm' rng/m3*' 20 150 270 15 37 1,250 60 -- 3,000 105 250 1.25 0.3 __ 30 4 2 10 3 . -- 6 1.5 35 1,000 17.5 0.75 0.6 68 0.75 10 6 44 18 20 Alb 12 6 27 -- 20 __ 20 150 790 150 810 -- ---- ---- -- 0.9 Capital letters refer to Appendices. Footnotes (a thru h) see Page 31. **See Notices of Intended Changes. SC ...... LAM025095 Substance ADOPTED VALUES TWA ppm* mg/m1*' TENTATIVE VALUES STEL ppm* mg/m1* Argon.............................. * Arsenic & compounds (as As)....................... Arsine............................ Asbestos (an forms)....... Asphalt (petroleum) fumes.......................... Azinphos methyl -- Skin Saygon (propoxur)........ Barium (soluble compounds)............... Benzene -- Skin............ 3snzidine production -- Skin.... p-Benzoquinone, see Quinone...................... Benzoyl peroxide............ 3enz(a)pyrene................ Benzyl chloride............... BeryBium........................ Biphenyl......................... Bismuth teBuride............ Bismuth teBuride, Se-doped.................... * Borates, tetra, sodium salts, Anhydrous................. Decahydrate............... Pentahydrate............. Boron oxide.................... Boron tribromide............ C Boron tiifiuoride............ Bromine......................... Bromine pentafluoride.... Bromochioromethane.... Bromoform -- Skin....... Butadiene (1, 3-butadiene)............... Butane............................ F __ 0.05 -- _ -- -- 10, A2 -- 0.1 -- -- 1 -- 0.2 -- __ -- -- -- 1 1 0.1 0.1 200 0.5 1,000 600 -- (0-5) 0.2 Ala 5 0.2 0.5 0.5 30, A2 Alb 0.4 5 A2 5 0.002 1 10 5 F -- -- -- __ -- -- -- -- -- 0.3 -- -- -- -- -- -- -- 1 5 i 10 10 3 0.7 0.7 1,050 5 -- -- -- 3 -- 0.3 0.3 250 -- 2,200 1,250 1,400 750 F -- -- Ala 10 0.6 1.5 -- *-- Alb 1.2 -- A2 -- 0.025 -- 20 10 __ 20 30 -- 2 2 1,300 -- 2,750 1,610 Capital letters refer to Appendices. Footnotes (a thru h) see Page 31. "See Notice of Intended Changes. 1977 Addition. 10 Substance ADOPTED VALUES TWA ppm" mg/m1*' TENTATIVE VALUES STEL ppm*' rog/m3* Butanethiol, see Butyl mercaptan................. 2-Butanone................... 2-Butoxy ethanol (Butyl Cellosolve) -- Skin.... n-Butyl acetate.............. sec-Butyl acetate............ tert-Butyl acetate............ C n-Butyl alcohol -- Skin.. sec-Butyl alcohol............ tert-Butyl alcohol............ C Butylamine -- Skin........ C tert-Butyl chromate (as CrOj) -- Skin............ n-Butyl glycidyl ether (BGE)......................... n-Butyl lactate............... Butyl mercaptan............. p-teit-Butyftoluene......... Cadmium, dust & salts (as Cd) ...................... C Cadmium oxide fume (as Cd)............................. Calcium carbonate......... Calcium arsenate (as As) Calcium cyanamide........ ** Calcium hydroxide......... ** Calcium oxide................ Camphor, synthetic........ Caprolactam Oust.......................... Vapor......................... * Captafol (Difolatan*) -- Skin... Captan........................... Carbaryf (Sevin*).......... Carbof'uran (Furadan*).. Caibon black................. Carbon dioxide.............. Caibon disulfide -- Skin 0.5 200 50 150 200 200 50 150 100 5 _ 50 5 0.5 10 _ _ -- -- -- -- -- 2 5 -- -- -- __ 5,000 20 1.5 590 300 885 240 150 720 710 200 950 950 250 1.190 950 150 450 2_50 __ 1.190 - 300 15 1--50 450 __ 0.1 270 25 -- 1.5 -- 60 20 __ __ 120 0.05 0.15 0.05 E 1 0.5 5 (5) 12 -- __ __ __ 3 20 _1 __ 18 1 20 10 3 40 0.1 5 5 0.1 3.5 9,000 60 -- _ _ 15,000 30 15 10 7 18,000 90 Capital letters refer to Appendices. "See Notice of Intended Changes. *1977 Addition. 11 SC 16293 - J LAM025096 Substance Carbon monoxide........... Carbon tetrabromide..... Carbon tetrachloride -- Skin.. * Catechol (Pyrocatechol).. Cellulose (paper fiber).... Cesium hydroxide........... Chiordane -- Skin.......... Chlorinated camphene-- Skin..... Chlorinated diphenyl oxide........................... Chlorine......................... Chlorine dioxide.............. C Chlorine trifluoride.......... C Chioroacetaldehyde........ a-Chloroacetophenone (Phenacyl chloride).... Chlorobenzene (Monochlorobenzene). o-Chlorobenzylidene malonoitrile -- Skin... Cnionobromomethane.... 2-Chloro-l, 3-butadiene, see/3 Chloroprene..... Chi orodifluoromethane. Cniorodiphenyl (42% Chlorine) -- Skin....... Chlorodiphenyl (54% Chlorine) -- Skin....... 1-Ch(oro. 2, 3-epoxy-propane (Epichlorhydrin)......... 2-Chioroethanol (Ethylene chlorohydrin)............. Chloroethylene (Vinyl chloride) .................... AOOPTEO VALUES TWA ppm"' mg/m3*' 50 55 0.1 1.4 TENTATIVE VALUES STEL ppm"' mg/m3*' 400 440 0.3 4.2 10 5 65 20 --25 160 -- ---- E-- 2-- 20 -- -- 0.5 -- 2 _ 0.5 -- i 0.5 -- 1.5 1 33 9 0.1 0.3 0.3 0.9 0.1 0.4 -- -- 1 3-- "" 0.05 0.3 -- -- 75 350 -- -- 0.05 0.4 _ -- 200 1,050 250 1,300 25 1,000 __ _ SO 3,500 1 0.5 35 1,250 -- -- 135 4,3/5 -- 1 5 20 10 40 13 Ale -- Ale -- lt Capital letters refer to Appendices. *1977 Addition. 12 Substance "Chloroform (Trichloromethane).... bis-Chloromethyl ether... 1-Chloro-1-nitro-propane Chloropicrin.................. ^-Chloroprene -- Skin.. Chlorpyrifos (Dursban) --Skin... o-Chlorostyrene............. o-Chlorotoiuene -- Skin. 2-Chloro- 6-(trichloromethyl pyridine (N-Serve*)... Chromates, certain insoluble forms......... Chromic add and Chromates, (as Cr.)... Chromium, Sol. chromic, chromous salts (asCr.)............. Clopidol (Coyden*)...... Coal tar pitch volatiles (See Particulate polycydic aromatic hydrocarbons)............ Cobalt metal, dust and fume.......................... Copper fume.................. busts & Mists............ Corundum (AI2O3).......... Cotton dust, raw............ Crag* herbicide............. Cresol, all isomers -- Skin........ Crotonaldehyde............. Cmfomate.................... Cumene -- Skin............ ADOPTEO VALUES TWA ppm*' mg/m3*' (25) 0.001 20 0.1 25 _ 50 50 (120) Ala 100 0.7 90 0.2 285 250 10 0.05A1a 0.05 0.5 -- 10 Ala (0.1) -- 0.2 ___ 1 --E ___ 0.2> ____ 10 5 22 26 ___ 5 50 245 TENTATIVE VALUES STEL ppm*' mg/m3*' Ala ___ __ 35 135 0.6 75 430 75 375 20 Ala __ 20 Ala __ __ __ 2 __ E ___ 0.6 20 6 18 20 75 365 m) See p. 34. Footnotes (a thru h) see Page 31. "See Notice of Intended Changes. 13 * V -1 fi :U1 i f' 4X i. 1 r* t. \ i 16294 j_________ LAM025097 Substance Cyanamide.................... Cyanide, as CN -- Skin.. Cyanogen ..................... Cydohexane.................. Cydohexanol.................. Cyclohexanone............... Cyclohexene................... Cyclohexylamine -- Skin Cydopentadiene............. 2. 4-D (2, 4-Diphenoxy- acetic acid)................ DDT (Dichlorodiphenyl- trichloroethane)......... DDVP. See Dichlorvos ... Decaborane -- Skin...... Demeton -- Skin........ Diacetone alcohol (4-hydroxy-4-methyl2-pentanone)............ 1,2-Diaminoethane, See Ethylenediamine......... Diazinon -- Skin........... Diazomethane............... Diborane...................... 1,2-Oibromoethane (Ethylene dibromide) -- Skin....................... Dibrom........................ 2-N-Dibutylaminoethanol -- Skin..................... Dibutyl phosphate......... Dibutyl phthalate........... ) Dichloracetylene........... ) o-Dichlorobenzene......... p-Oichlorobenzene......... Dichlorobenzidine -- Skin.......................... Dichlorodilluoromethane. ADOPTED VALUES TWA ppm" mg/m**1 TENTATIVE VALUES STa ppm*' mg/m**' -- 2-- -- -- 5-- -- 10 20 -- -- 300 1,050 375 1,300 50 200 -- -- 50 200 300 1,015 10 40 -- -- -- -- -- 75 200 150 400 10 20 -- 1-- 3 0.1 1 0.3 3 0.05 0.3 0.15 0.9 0.01 0.1 0.03 0.3 50 240 75 360 10 25 -- -- -- 0.1 -- 0.3 0.2 0.4 -- --0.1 0.1 20 -- 2 1 -- 0.1 50 75 -- 1,000 145 30 3 "" 14 5 5 0.4 300 450 A2 4,950 4 2 -- -- -- 110 -- 1,250 220 6 28 10 10 -- -- 675 A2 6,200 ! | i : ; i ; j il i 1 Capital letters refer to Appendices. Footnotes (a thru h) see Page 31. *1977 Addition. 14 I \ Substanceppm*' mg/mJ>> ADOPTED TENTATIVE VALUES__________VALUES TWA ppm*1 mg/m3>l STa 1,3-Dichloro-5, 5-dimethyl hydantoin.. -- 1.1-Oichloroethane....... 200 1,2-Dichloroethane....... 50 1.2-Dichloroethylene.... 200 Dichloroethyl ether-- Sian............................ 5 Dichloromelhane, see Methylene chloride.... 200 ** Dichloromonofluoro- methane..................... (1.000) Cl, 1-Dichloro-1- nitroethane................. 10 1,2-Dichloropropane, see Propylene dichloride................... Dichlorotetrafluoro- 75 ethane........................ 1,000 Dichlorvos (DDVP) -- Skin....................... 0.1 * Dicrotophos (Bidrin) -- Skin............................ -- Dicyclopentadiene.......... Dicydopentadienyl iron.. 5 -- Dieldrin -- Skin............. __ Diethylamine.................. Diethylaminoethanol -- 25 Skin............................ 10 Diethylene triamine -- Skin............................ Diethyl ether, see Ethyl 1 ether........................... Diethyl phthalate............ 400 -- Difluorodibromomethane. C Diglyddyl ether (DGE).... 100 0.5 Dihydroxybenzene, see Hydroquinone............ -- Diisobutyl ketone........... 25 0.2 820 200 790 30 720 (4.200) 60 350 7.000 1 0.25 30 10 0.25 75 50 4 1,200 5 860 2.8 2 150 _ 250 75 250 10 250 _ _ 110 1.250 0.3 _ _ -- __ -- 500 150 _ 0.4 1,025 300 1.000 60 900 _ 525 8.750 3 _. _ 20 0.75 __ 1,500 10 1,290 3 Capital letters refer to Appendices. 1977 Addition. "See Notice of Intended Changes. 15 ! SC 16295 t. LAM025098 ADOPTED VALUES TWA Substanceppm" mg/m1*' TENTATIVE VALUES STEL ppm*' mg/mjtl Oiisopropylamine -- Skin............................ 5 Dimethoxymethane, see Melhylal..................... 1,000 Dimethyl acetamide -- Skin............................ to Dimethylamine............... 10 Dimethylaminobenzene, see Xylidene............... 5 Cimetiiylaniline (N-Dimethylaniline) -- Skin............................ 5 Dimethylbenzene, see Xylene........................ 100 Dimsthyl-1, 2-dibromo-2-dichloroethyl phosphate, see Dibrom....................... -- Dimethyltormamide -- S<in............................ 10 2. 5-Dimethylheptanone, see Diisobutyl ketone.. 25 1.1-Dimethylhydrazine -- Skin....................... Oimethylphthalate........... 0.5 -- C Dimethyl sulfate -- Skin............................ 0.1, A2 Dinitrobenzene (all isomers) -- Skin........ Dinitro-o-cresol -- Skin . 0.15 -- 3, S-Oinitro-o-toluamide (Zoalene*)................. Dinitrotoluene -- Skin ... . -- Dioxane, tech, grade -- Skin............................ 50 Dioxathion (Delnav)..... -- Diphenyl, see Biphenyl... 0.2 Diphenylamine............... -- 20 3,100 35 18 25 25 435 3 30 150 1 5 0.5, A2 1 0.2 5 1.5 180 0.2 1 10 -- 1,250 15 -- 10 10 150 20 1 -- _ 0.5 -- -- -- 0.6 -- -- 3,875 50 -- 50 50 650 6 60 2 10 _ 3 0.6 10 5 -- 3 20 Capital letters refer to Appendices. *1977 Addition. Footnotes (a thru h) see Page 31. 16 ADOPTED VALUES TWA Substanceppm** mg/m]>> TENTATIVE VALUES STEL ppm*1 mg/m** Diphenytmethane diisocyanate, see Methylene bisphenyl isocyanate (MDI)........ Dipropylene glycol methyl ether -- Skin .. Diquat........................... Di-sec, octyl phthalate (Di-2-ethylhexylphthalate).................. Disulfuram..................... Disyston -- Skin............ 2. 6-Diteit butyl-p-cresol............ ' Diuron........................... Dyfonate........................ Emery............................ Endosulfan (Thiodan) -- Skin...................... Endrin -- Skin.............. Epichiorhydrin -- Skin... EPN --Skin.................. 1, 2-Epoxypropane, see Propylene oxide......... 2. 3-Epoxy-1-propanol, see Glyddot................ Ethane........................... Ethanethiol, see Ethyl mercaptan................. Ethanobmine................. Ethion (Nialate) -- Skin 2-Ethoxyetiianol -- Sian. 2-Ethoxyethyl acetate (Cellosotve acetate) -- Skin........................... Ethyl acetate.................. Ethyl acrylate--Skin.... Ethyl alcohol (Ethanol)... Ethylamine..................... 0.02 100 -- -- -- .. -- -- -- _ -- 5 -- 100 50 F 0.5 3 -- 100 100 400 25 1,000 10 0.2 600 0.5 5 2 0.1 10 10 0.1 E 0.1 0.1 20 0.5 240 150 -- 1 6 0.4 370 540 1,400 100 1,900 18 0.02 150 -- __ -- -- __ 10 __ 150 65 F 1.5 6 -- 150 150 -- -- -- -- 0.2 900 1 10 5 0.3 20` _ 20 0.3 0.3 40 1.5 360 190 __ 3 12 -- 560 810 -- -- -- -- Footnotes (a thru h) see Page 31. *1977 Addition. 17 SC 16296 >__ LAM025099 Substance ADOPTED VALUES TWA ppma> mg/m11" TENTATIVE VALUES STEL ppm"' mg/mJ*' Ethyl sec-amyl ketone (4-M ethyl-3- heptanone)................. 25 Ethyl benzene................. 100 Ethyl bromide................ 200 Ethylbutyl ketone (3-Heptanone)............ 50 Ethyl chloride................. 1,000 Ethyl ether..................... 400 Ethyl foimate................. 100 Ethyl mercaptan.............. 0.5 Ethyl silicate................... (100) Ethylene......................... F C Ethylene chlorohydrin -- Skin............................ 1 Ethylene diamine............ 10 Ethylene dibromide, see 1.2-0ibromoethane... 20 Ethylene dichloride, see 1,2-Oichloroethane... 50 Ethyleneglycol, Particulate................. -- Vapor......................... 100 C Ethylene glycol dinitrate and/or Nitroglycerin -- Skin....................... 0.2- Ethylene glycol monomethyl ether acetate (Methyl cellosolve acetate) -- Skin............................ 25 Ethylene oxide................ 50 Ethylenimine -- Skin..... 0.5 Ethylidene chloride, see 1,1-Oichloroethane... 200 C Ethylidene notbomene... 5 N-Ethylmorpholine -- Skin............................ Fensulfothion (Dasanit).. 20 -- Ferbam........................... -- ------------------ Capital letters refer to Appendices. 130 -- 435 125 890 250 230 2,600 1,200 300 1 (850) 75 1,250 500 150 -- -- F 3-- 25 -- 145 30 200 75 10 -- 260 125 ---- 120 40 90 75 1-- 320 250 25 -- 94 20 0.1 -- 10 -- -- 545 1,110 345 3,250 1,500 450 -- -- -- -- -- 220 300 20 325 -- 180 135 -- 400 -- 94 -- 20 Substance Ferrovanadium dust....... Fluoride (as F)................ Fluorine......................... Fluorotrichloromethane.. C Formaldehyde................ Formamide..................... Formic acid.................... Furfural -- Skin............. Furftryl alcohol -- Skin . Gasoline......................... Germanium tetrahydride. Glass, fibrous" or dust.. "C Glutaraldehyde, activated or unactivated............ Glycerin mist................. Glycidol (2, 3-Epoxy- 1-propanol)................ Glycol monoethyl ether. see 2-Ethoxyethanol... Graphite (Synthetic)...... Guthion, see Azinphos-methyl........ Gypsum......................... Hafnium......................... Helium........................... Heptachlor --Skin........ Heptane (n-Heptane)..... Hexachlorocyciopenta- diene.......................... Hexachloroethane -- Skin............................ Hexachloronaphthalene -- Skin...................... Hexafluoroacetone......... Hexane (n-hexane). 2-Hexanone, see Methyl butyl ketone -- Skin .. Hexone (Methyl isobutyl ketone) -- Skin......... ADOPTED VALUES TWA ppm*' mg/m1*' __ -- 1 1,000 2 20 5 5 5 -- 0.2 -- 1 2.5 2 5,600 3 30 9 20 20 82 0.6 E -- (0.25) --E 50 150 100 370 --E -- 0.2 --E -- 0.5 F-- -- 0.5 400 1,600 0.01 0.11 1 10 -- 0.2 0.1 0.7 100 360 25 100 100 410 TENTATIVE VALUES STEL ppm*' mg/m1** __ 2 1,250 0.3 4 7.000 30 45 59 15 60 10 40 82 0.6 1.8 __ E __ __ E 75 225 150 560 __ __ __ 0.6 __ 20 -- 1.5 F-- 1.5 500 2,000 0.03 0.33 3 30 -- 0.6 0.3 2.1 125 450 40 150 125 510 Capital letters refer to Appendices. ' 'See Notice of Intended Changes. Baca iw a ro O T S K i . ' sc 16297 LAM025100 Substance sec-Hexyl acetate........... 1 Hexylene glycol.............. ' Hydratne -- Skin.......... Hydrogen........................ Hydrogenated terphenyls Hydrogen bromide.......... ! Hydrogen chloride......... Hydrogen cyanide -- Skin............................. Hydrogen fluoride........... Hydrogen peroxide........ Hydrogen selenide.......... Hydrogen sulfide............ Hydroquinone................ Indene............................. Indium & Compounds (as In)......................... Iodine.............................. iodoform......................... Iron oxide fume.............. Iron pentacarbonyl......... Iron salts, soluble (as Fe).............................. Isoamyl acetate.............. Isoamyl alcohol.......... Isobutyl acetate.............. Isobutyl alcohol.............. : Isophorone.................... Isophorone dfisocyanate -- Skin.. Isopropyl acetate............ Isopropyl alcohol -- Skin Isopropylamine............... Isopropyl elher............... Isopropyl glycidyl ether (I6E)........................... Kaolin.............................. Ketene............................ ADOPTED VALUES TWA ppm"1 mg/m**1 50 300 25 125 0.1 0.1 F-- 0.5 5 3 10 57 TENTATIVE VALUES STEL ppm"' mg/m**' __ __ ---- ---- F-- ---- ---- ---- 10 3 1 0.05 10 -- 10 -- 0.1 0.2 B3 0.01 -- 100 100 150 50 5 0.01 250 400 5 250 11 15 2-- 1.4 2 0.2 -- 15 15 2-- 45 15 16 __ 2.8 27 4 27 0.1 1 3 5 0.08 -- __ 0.4 __ -- 0.3 __ 0.6 10 1 __ 525 125 360 125 700 187 150 75 25 -- 2 655 450 875 225 -- 0.06 -- -- 950 310 1,185 980 500 1,225 12 10 24 1,050 310 1,320 50 240 75 360 -- E-- 20 0.5 0.9 1.5 2.7 Capital tetters refer to Appendices. *1977 Addition. 20 ADOPTED TENTATIVE VALUES__________ VALUES TWA STEL Substanceppm" mg/m1*' ppm*1 mg/m3>> Lead, inorg., fumes & dusts (as Pb)............. Lead arsenate (as Pb).... Lead Chromate (as Cr)... Limestone...................... Lindane -- Skin.............. Lithium hydride............. L.P.6. (Liquified petroleum pas)........... Magnesite....................... Magnesium oxide fume.. Malathion --Skin......... Maleic anhydride............ C Manganese & Compounds (as Mn).. Manganese cydopentadienyl tricarbonyl (as Mn) -- Skin............................ Marble............................ Mercury (Alkyl compounds) -- Skin, AsHg......................... Mercury (All forms except alkyl) as Hg .... Mesityl oxide................. Methane......................... Methanethiot, see Methyl mercaptan................. * Methomyl (Lannate*) -- Skin............................ Methoxychlor................. 2-Methoxyethanol -- Skin (Methyl cellosolve)................. Methyl acetate................ Methyl acetylene (propyne)................... -- 0.15 -- 0.15 -- 0.05, A2 --E -- 0.5 -- 0.025 1,000 -- -- -- 0.25 1,800 E 10 10 1 --5 -- 0.1 --E 0.001 -- 25 F 0.5 -- -- 0.01 0.05 100 1 2.5 10 25 200 1,000 80 610 .650 -- -- -- ------- -- 1,250 -- ____ _ _ -- -- 0.003 __ F -- 35 250 1,250 0.45 0._45_ 20 1.5 2,250 20 -- 0.3 20 0.03 0.15 = -- 120 760 2,060 `1977 Addition. Capital tetters refer to Appendices. 21 <9 3 SC 16298 LAM025101 Substance ADOPTED VALUES TWA ppm*' mg/m," TENTATIVE VALUES STEL ppm*' mg/mjl" Methyl acetylene-propadiene mixture (MAPP)......... Methyl acrylate -- Skin.. Methyl acrylonitrile -- Skin............................ Methyla! (dimethoxymethane).. Methyl alcohol (methanol) -- Skin.... Methytamine................... Methyl amyl alcohol, see Methyl isobutyl carbinol.................... Methyl 2-cyanoacrylate.. Methyl isoamyl ketone... Methyl n-amyl ketone (2-Heptanone)............ Methyl bromide -- Skin . Methyl butyl ketone, see 2-Hexanone................ Methyl cellosolve -- Skin see 2-Methoxyethanol. Methyl cellosolve acetate -- Skin, see Ethylene glycol monomethyl ether acetate............... Methyl chloride............... Methyl chloroform......... Methylcydohexene........ Methylcydohexanol........ o-Methycyclohexanone -- Skin....................... Methylcydopentadienyl manganese tricarbonyl (as Mn) -- Skin.......... Methyl demeton -- Skin. ; Methylene bisphenyl isocyanate (MDI)........ 1,000 10 1 1,000 200 10 25 2 100 100 15 25 25 25 100 350 400 50 50 0.1 -- 0.02 1,800 1,250 35 -- 32 3,100 1,250 260 250 12 -- 100 40 84 475 150 465 150 60 -- 100 40 80 35 120 210 1,900 1,600 235 230 35 125 450 500 75 75 0.2 0.3 0.5 -- 0.2 -- 2.250 -- 6 3.875 325 -- 150 16 710 710 -- 150 120 150 260 2.375 2,000 350 345 0.6 1.5 -- Capital letters refers to Appendices. 22 Substance ADOPTED VALUES TWA ppm*' mg/m**' * Methylene chloride (dichloromethane)...... 4,4'-Methylene bis (2-chloraniline) -- Skin............................ C Methylene bis (4-cydo- hexylisocyanate)........ Methyl ethyl ketone (MEK), see 2-Butanone................ C Methyl ethyl ketone peroxide..................... Meihyl tormate............... Methyl iodide --Skin.... Methyl isobutyl carbinol -- Skin...................... Methyl isobutyl ketone, see Hexone ................ Methyl isocyanate-- Skin............................ Methyl mercaptan........... Methyl methacrylate....... Methyl parathion -- Skin Methyl propyl ketone, see 2-Pentanone........ C Methyl siicate................ C tt-Meihyl styrene............ Molybdenum (as Mo) Soluble compounds... Insoluble compounds. * Monocrotophos (Azodrin)................. Monomethyl aniline -- Skin............................ C Monomethyl hydrazine -- Skin....................... Morpholine --Skin........ Naphthalene................... 200 0.02, A2 0.01 200 0.2 100 5 25 too 0.C2 0.5 100 -- 200 5 100 -- 2 0.2 20 10 720 0.11 590 1.5 250 28 100 410 0.05 1 410 0.2 700 30 480 5 10 0.25 9 0.35 70 50 TENTATIVE VALUES STEL ppm" mg/m**` 250 900 A2 250 150 10 40 125 125 - 250 ____ ___ 740 375 56 . 150 510 -- 510 0.6 875 - 10 20 4 18 30 105 15 75 Capital letters refer to Appendices. Footnotes (a thru h) see Page 31. *1977 Addition. 23 \" SC 16299 V.-------------J. LAM025102 I: Substance ADOPTED VALUES TWA ppm"' mg/m1*' TENTATIVE VALUES STEL ppm" mg/mJ*` /3-Naphthylamine........... Neon............................... * Nickel carbonyl............... Nickel metal................... Nickel, soluble compounds (as Ni)__ Nicotine--Skin............ Nitric add....................... Nitric oxide..:................ p-NitroaniGne-- Skin.... Nitrobenzene --Skin...... p-Nitrochlorobenzene-- Skin............................ 4-Nitrodiphenyl............... Nitroethane.................... C Nitrogen dioxide............ Nitrogen tritluoride........ Nitroglycerin10 --Skin... Nitrom ethane................. 1-Nitropropane............... 2-Nitropropane.............. N-NitrosocGmethylamine (dimethytnitrosoamine) -- Skin....................... Nitrotoluene -- Skin....... Nitrotrichloromethane, see Chloropicrin......... Nonane........................... Octachloronaphthalene -- Skin....................... Octane............................ Oil mist........................... Osmium tetroxide (as Os)............................. Oxalic add...................... Oxygen difluoride........... Ozone.................. ........ Paraffin wax fume.......... -- F 0.05 -- . -- 2 25 1 1 _ -- 100 5 10 0.2 100 25 25 5 0.1 200 300 -- 0.0002 -- 0.05 0.1 -- Alb -- 0.35 1 0.1 0.5 5 30 6 5 1 Alb 310 9 29 2 250 90 90 -- F -- -- _ -- 4 35 2 2 -- 150 -- 15 -- 150 35 -- A2 30 10 0.7 1,050 0.1 1,450 5 0.3 250 _ 375 -- 0.002 1 0.1 0.2 2 0.0006 -- 0.15 0.3 -- Alb -- -- -- 0.3 1.5 10 45 12 10 2 Alb 465 -- 45 -- 375 135 -- A2 60 2 1,300 0.3 1,800 10 0.006 2 0.3 0.6 6 Capital letters refer to Appendices. Footnotes (a thru h) see Page 31. *1977 Addition. 24 Substance * Paraquat--Skin............ Parathion -- Skin........... Paniculate polycyclic aromatic hydrocarbons (PPAH) as benzene solubles... Pentaborane.................. Pentachloronaphthalene. Pentachlorophenol-- Skin............................ Pentaerythritol................ Pentane......................... 2-Pentanone................... Perchloroethylene -- Skin............................ Perchloromethyt mercaptan................. Perchloiyl fluoride......... Petroleum distillates (naphtha)................... Phenol -- Skin............... Phenothiazine -- Skin.... p-Phenytene diamine -- Skin............................ Phenyl ether (vapor)....... Phenyl ether-Diphenyt mixture (vapor)......... Phenylethylene, see Styrene...................... Phenyl glyddyl ether (PGE)......................... Phenythydrazine -- Skin. I Phenylphosphine............ Phorate (Thrmet) -- Skin............................ Phosdrin (Mevinphos) -- Stan...................... Phosgene (carbonyl chloride).................... ADOPTED VALUES TWA ppm" mg/m1*' _ (0.5) -- 0.1 TENTATIVE VALUES STEL ppm" mg/m1*1 ..__ __ 0.3 -- 0.2, Ala 0.005 -- 0.01 0.5 -- 0.5 --E 600 1,800 200 700 __ 0.015 __ __ __ 750 250 100 670 150 0.1 0.8 _ 3 14 6 >B3 __ 63 5 19 10 __ 5 __ 0.1 __ 1 72 1 72 100 420 125 10 60 15 5 22 10 0.05 0.25 __ -- 0.05 __ 0.01 0.1 0.03 0.10 0.4 -- Ala 0.03 1.5 1.5 20 2.250 875 1.000 . 28 __ 38 10 __ 14 14 525 90 44 0.15 0.3 -- Capital letters refer to Appendices. "See Notice of Intended Changes. 25 *5 ,j 1 sc 16300 LAM025103 Substance Phosphine..................... Phosphoric add.............. Phosphorus (yellow)..... Phosphorus pentschloride............. Phosphorus pentasulfide Phosphorus trichloride... * Phthalic anhydride......... * m-PhJialodinitrJe........... Pidoram(Tordon*)....... Picric add--Skin.......... Pival(2-PivalyM, 3- ndancSone)................ Plaster of Paris............... Platinum (Soluble salts) asPt........................... Poiychlorobiphenyls. see Chiorodiphenyts......... Pclyteaafluoroethylene decomposition products.................... G Potassium hydroxide..... Propane......................... /S-Propiolactone.............. Propargyl alcohol -- Skin............................ n-Propyl acetate.............. Propyl alcohol-- Skin... n-Propyl nitrate............. Propylene....................... Propylene dichloride (1. 2-Oichloropropane).... Propylene glycol monomethyl ether..... Propylene im'me -- Skin. Propylene oxide............. Propyne, see Methyl-acetylene........ Pyrethrum..................... ADOPTED VALUES TWA ppm" mg/m3*' 0.3 0.4 --1 -- 0.1 TENTATIVE VALUES STEL ppm" mg/m3*' 11 --3 -- 0.3 -- 1-- 3 -- 1-- 3 0.5 3-- -- 1 64 24 -- 5-- -- -- 10 -- 20 -- 0.1 -- 0.3 -- 0.1 --E -- 0.002 -- -- -- 0.3 20 -- -- ---- -- -- -- F -- 1 200 200 25 F 75 100 2 100 .000 -- B1 -- 2-- --F A2 -- 23 840 250 500 250 110 40 --F 350 115 360 150 5-- 240 150 1.650 1,250 5-- B1 -- -- A2 6 1.050 625 140 -- 525 450 -- 360 2,050 10 Capital letters refer to Appendices *1977 Addition. 26 Substance ADOPTED VALUES TWA ppm" mg/m3*' TENTATIVE VALUES STEL ppm" mg/m3" Pyridine.......................... Quinone......................... RDX--Skin................... Resordnol..................... Rhodium, Metal fume and dusts (as Rh)....... Soluble salts............... Ronnd............................ Rosin core solder pyrolysis products (as formaldehyde)............ Rotenone (commercial).. Rouge................ ........... * Rubber solvent............... Selenium compounds (as Se)............................. Selenium hexafluoride, as Se.......................... Sevin* (see Carbaiyt).... Silane (see SiGcon tetrahydride)............... Silicon............................ Silicon carbide............... SiScon tetrahydride (Silane)....................... Silver, metal and soluble compounds, as Ag.... C Sodium azide................. Sodium fluoroacetate (1080) --Skin........... C Sodium hydroxide......... Starch ............................ Stibine............................ Stoddard solvent............ Strychnine...................... Styrene, monomer (Phenytethylene)........ ** Sucdnaldehyde (see Gluiaraldehyde)......... 5 0.1 -- 10 -- -- -- -- -- -- 400 -- 0.05 -- 0.5 -- -- 0.5 -- 0.1 -- -- -- 0.1 100 -- 100 -- Capital letters refer to Appendices. *1977 Addition. "See Notice of Intended Changes. 15 0.4 1.5 45 0.1 0.001 10 10 0.3 -- 20 -- -- -- 0.1 -- 5 . --- E 1,600 -- _ 0.2 __ 0.4 0.05 5-- 7-- E-- E __ 0.7 0.01 0.3 1 -- __ 0.05 2 E 0.5 575 0.15 -- -- -- 0.3 150 -- 420 125 (0.25) -- 30 1 3 90 0.3 0.003 __ 0.3 10 20 __ __ 0.4 10 ... 20 20 1.5 0.03 __ 0.15 -- 20 1.5 720 0.45 525 -- 27 sc 16301 ! ii <' .1 i to l i3 IM \ * . Hi :3 l* ` *1 LAM025104 ADOPTED VALUES TWA Substanceppm*1 mg/m1** TENTATIVE VALUES STEL ppm*1 mg/m1*' C Subtilisins (Proteolytic enzymes as 100% pure crystalline enzyme)...................... Sucrose.......................... Sulfur dioxide................ Sulfur hexafluoride......... Sulfuric add.................... Sulfur monochloride....... Sulfur pentafiuoride....... Sulfur letrafluoride.......... Sulfur/ fluoride.............. Systox, see Demeton... 2.4, 5-T......................... Tantalum......................... TEDP --Skin.................. Teflon* decomposition products.................... Tellurium........................ Tellurium hexafluoride, as Te........................... TEPP--Skin.................. CTerphenyls...................... 1,1,1,2-Tetrachloro-2, 2-tSfluoroethane......... 1,1.2,2-Tetrachloro-1, 2-difluoroethane........ 1,1.2. 2-Tetrachloroethane -- Skin....................... Tetrachloroethylene, see Perchloroethylene....... Tetrachloromethane. see Carbon tetrachloride... Tetrachloronaphthalene.. Tetraethyl lead (as Pb) -- Skin....................... 0.00006" --E S 13 1.000 -- 6,000 1 16 0.025 0.25 0.1 0.4 5 20 0.01 -- -- -- 0.1 10 5 0.2 _ 81 -- 0.1 0.02 0.004 1 0.2 0.05 9 500 4,170 500 4,170 5 35 100 670 10 65 --2 _ 0.100*' -- -- 1,250 -- 3 0.075 0.3 10 0.03 -- -- -- __ -- 0.012 -- 625 625 10 150 20 -- __ 20 -- 7,500 -- 18 0.75 1 40 0.3 20 10 0.6 B1 -- 0.15 -- 5,210 5.210 70 1.000 130 4 0.3 Capital letters refer to Appendices. Footnotes (a thru h) see Page 31. o) See Page 34. 28 Substanceppm*1 mg/m1*' ADOPTED TENTATIVE VALUES__________ VALUES TWA STEL ppm*' mg/m1* Tetrahydrofuran............. Tetramethyl lead (as Pb) 200 590 250 700 -- Skin...................... -- 0.150" -- 0.45 Tetramethyl sucdnonitrile -- Skin. 0.5 3 1.5 9 Tetranitromethane......... 1 8 Tetiyl (2,4, 6-trinitrophenyl- methylnitramine) -- Skin........................... Thallium, soluble 1.5 3.0 compounds (as Tl) -- Skin........................... 4,4 '-Thiobis (6-tert -- 0.1 -- -- butyl-m-cresol)........... -- 10 -- .. 20- Thiram*......................... 5 10 Tin, inorganic compounds, except SnH and Sn02> (as Sn) -- 2-- 4 Tin, organic compounds (as Sn) -- Skin......... Tin oxide....................... Titanium dioxide............ -- -- -- 0.1 -- E-- E-- 0.2 20 20 Toluene (toluol) --Skin. 100 375 150 560 C Toluene-2,. 4-diisocyanate (TDI)... 0.02 0.14 -- -- o-Toluidine..................... 5 22 10 44 Toxaphene, see Chlorinated camphene -- 0.5 -- 1.5 Tributyl phosphate......... -- 5 5 1,1,1-Trichloroethane, see Methyl chloroform 350 1,900 440 2,380 1,1,2-Trichloroethane -- Skin...................... 10 45 20 90 Trichloroethylene.......... 100 535 150 800 ** Trichloromethane, see Chloroform................ (25) (120) -- -- Trichloronaphthalene..... 5-- 10 1,2,3-Trichloropropane 50 300 150 450 Capital letters refer to Appendices. "See Notice of Intended Changes. 29 Sc 16302 LAM025105 ADOPTED VALUES TWA Substanceppm*11 mg/m1*' TENTATIVE VALUES STEL ppm"1 mg/m^1 1,1. 2-Trichloro 1.2. 2-trifluoroethane........ Triethylamine................. Tricyclohexyltin hydroxide (Plictran*). Trifiuoromonobromo- methane..................... Trimethyl benzene......... 2, 4, 6-Trinitrophenol, see Picric acid............ 2, 4, 6-Trinitrophenyl- methylnitramine, see Tetryl......................... Trinitrotoluene (TNT) -- Skin............................ Triorthocresy! phosphate Triohenyl phosphate....... Tungsten & compounds, as W Soluble................... Insoluble................ Turpentine..................... Uranium (natural) soluble & insoluble compounds, as U....... Vanadium (V2O5). asV ; Dust........................... Fume......................... Vinyl acetate................... Vinyl benzene, see Styrene..... ................ Vinyl bromide................ ' Vinyl chloride................. Vinyl cyanide, see Acrylonitrile................ ' Vinyl cyclohexene dioxide ...................... Vmylidene chloride........ Vinyl toluene................... 1,000 25 -- 1,000 25 -- -- -- -- -- -- -- 100 -- -- -- 10 100 (250) (200) 20 10 10 100 7,600 1,250 100 40 5-- 6,100 1,200 120 35 0.1 -- 1.5 (15) 0.1 3 -- -- -- -- 1-- 5-- 560 150 0.2 0.5 0.05 30 420 (1.100) (510) 45 60 40 480 -- -- -- 20 150 -- -- 30 -- 20 150 9,500 150 10 7,625 180 0.3 3.0 -- 0.3 6 3 10 840 0.6 1.5 -- 60 630 -- -- 70 -- 80 720 *1977 Addition. `See Notice of Intended Changes. 30 ADOPTED VALUES TWA Substanceppm" mg/m**1 Warfarin......................... * Welding fumes (Total particulate)................. Wood dust (nonallergenic).......... Xylene (0-, m-, p-isomers) -- Skin.... *C m-Xylene a. a'-diamine. Xyfidene -- Skin............ Yttrium.......................... Zinc chloride fume......... * Zinc chromate (as Cr).... Zinc oxide fume............. Zinc stearate.................. Zirconium compounds (as Zr)....................... -- 0.1 -- 5, B3 --5 100 435 -- 0.1 5 25 --1 --1 -- 0.05, A2 --5 --E --5 TENTATIVE VALUES STEL ppm*` mg/m1*1 __ 0.3 B3 10 150 655 -- __ 10 50 __ 3 __ 2 -- __ 10 __ 20 10 *1976 Addition Capital letters refer to Appendices. a) Parts ot vapor or gas per million parts of contami nated air by volume at 25C and 760 mm. Hg. pres sure. b) Approximate milligrams of substance per cubic meter of air. d) An atmospheric concentration of not more than 0.02 ppm, or personal protection may be necessary to avoid headache for intermittent exposure. e) < 7 ^m in diameter. f) As sampled by method that does not collect vapor. g) According to analytically determined composition. h) For control of general room air, biologic monitoring is essential for personnel control. Radioactivity: For permissible concentrations of radio isotopes in air, see U.S. Department of Commerce, Na tional Bureau of Standards Handbook 69, "Maximum Permissible Body Burdens and Maximum Permissible Concentrations of Radionuclides in Air and in Water for 31 Is af : ; '2 j. Sc l6303 LAM025106 Occupational Exposure," June 5, 1969. Also, see U.S. Department of Commerce National Bureau of Standards, Handbook 59, "Permissible Dose from External Sources of Ionizing Radiation," September 24.1954, and adden dum of April 15,1958. A report, Basic Radiation Protec tion Criteria, published by the National Committee on Radiation Protection, revises and modernizes the con cept of the NCRP standards of 1954, 1957 and 1958; obtainable as NCRP Rept. No. 39, P. 0. Box 30175, Washington. D.C. 20014. Substance MINERAL DUSTS SiUCA, SiOt Crystalline Quartz TLV in mppcf0: 300* % quartz +10 TLV for respirable dust mg/m3: 10 mg/m3** in % Respirable quartz + 2 TLV for "total dust," respirable and nonrespirable: 30 mg/m3 % quartz + 3 Cristobalite.............Use one-half the value calculated from the count or mass formulae for quartz. Tridymite Use one-half the value calculated from formulae for quartz. Silica, fused Use quartz formulae. Tripoli Use respirable*' mass quartz for mula * *Amorphous...................................................20 mppcf1' "See Notice of Intended Changes. 32 SILICATES (< 1% quartz) Asbestos, all formst Graphite (natural) Mica Mineral wool fiber Perlite Portland Cement Soapstone Talc (nonasbestiform) Talc (fibrous), use Asbestos limit. Tremolite, see Asbestos. 5 fibers/cc> 5/im in length"*; Ala 15 mppcf 20 mppcf 10 mg/m3 30 mppcf 30 mppcf 20 mppcf 20 mppcf COAL DUST 2 mg/m3 (respirable dust fraction < 5% quartz), if > 5% quartz, use respirable mass formula. NUISANCE PARTICULATES (see Appendix E) 30mppcfor10mg/m3H of total dust < 1 % quartz, or, 5 mg/m3 respirable dust. Conversion factors: mppcf x 35.3 = Million particles per cubic meter = particles per c.c.i) i) Millions of particles per cubic foot of air, based on impinger samples counted by light-field technics. j) The percentage of quartz in the formula is the amount determined from airborne samples, except in those instances in which other methods have been shown to be applicable. k) Both concentration and percent quartz for the appli cation of this limit are to be determined from the fraction passing a size-selector with the following characteristics: tA more stringent TLV for crotidoSte may be required. I), n) Seep. 34. 33 * ! SC 16304 i--. - j LAM025107 SC 16305 LAM025108 10 T Rjure 8 -- Threshold i 11 Conditioned (tanro==-- posure in excess of ~ However, such cnnor-- against skin cancer. NOTICE OF These physical aae^sr ues, comprise those --------proposed for the first------"Adopted" listing has -- proposed limits shnmrr ----remain in the listing fr- - after one year no evice==s the appropriateness or----be reconsidered for the^ SC 16306 onds times the pulse repetition rate in Hertz. Expo sure during an 8-hour workday shall not exceed the following values which are averaged over any 0.1 hour period: Power Density Energy Density Mean Squared Electric Field Strength Mean Squared Magnetic Field Strength 10mW/cm2 1 mWh/cm2 40,000 V2/m2 0.25 A2/m2 4. Exposure is not permissible in CW or repetitively pulsed fields with an average power density in excess of 25 mW/cm2 or approximate equivalent tree-space field strengths of 300 V/m or 0.75 A/m. NOTICE OF INTENT TO ESTABLISH THRESHOLD LIMIT VALUES LIGHT AND NEAR-INFRARED RADIATION These Threshold Limit Values refer to visible and near-infrared radiation in the wavelength range of 400 nm to 1400 nm and represent conditions under which it is believed that nearly all workers may be exposed with out adverse effect. These values should be used as guides in the control of exposure to light and should not be regarded as a fine line between safe and dangerous levels. Recommended Values: The Threshold Limit Value for occupational exposure to broad-band light and near-infrared radiation for the eye apply to exposure in any eight-hour workday and require knowledge of the spectral radiance (L*) and total irradiance (E) of the source as measured at the posi tion^) of the eye of the worker. Such detailed spectral data of a white fight source is generally only required if the luminance of the source exceeds 1 cd cm-2. At lu minances less than this value the TLV would not be ex ceeded. The TLVs are: 1. To protect against retinal thermal injury, the spectral radiance of the lamp weighted against the function R 90 (Table 11) should not exceed: MOO ,____ 2L*R*AXS vTT/at 400 (1) where Lx is in W cm~* sr*1 and t is the viewing duration (or pulse duration if the lamp is pulsed) lim ited to 1 ms; to 10 s, and a is the angular subtense of the source in radians. If the lamp is oblong, a refers to the longest dimension that can be viewed. For in stance, at a viewing distance r = 100 cm from a tubular lamp of length I - 50 cm, the viewing angle is: a = llt -- 50/100 = 0.5 rad (2) 2. To protect against retinal injury from chronic bluelight exposure the integrated spectral radiance of the lamp weighted against the blue-light hazard function 8X (Table 11) should not exceed: 'J? L*. t B* AX s ioo Jem-* sr> (t s ios) (3a) J Lx Bx ax 10-* Wcm-* sr1 (t > 10`s) (3b) For a source radiance L which exceeds 2 mW cm"2 sr-1 in the blue spectral region, the permissible ex posure duration t,,,in seconds is simply: t,,,, = 100 J cm-2 sr"VL (blue) (4) The latter limits are greater than the maximum per missible exposure limits for 440 nm laser radiation (see Laser TLV) because a 2-3 mm pupil is assumed rather than a 7 mm pupil for the Laser TLV. 3. Infrared Radiation: To avoid possible delayed effects upon the lens of the eye (cataractogenesis), the infra red radiation (X > 770 nm) should be limited to 10 mWcm *. For an infrared heat lamp or any near-in frared source where a strong visual stimulus is ab sent, the near infrared (770-1400 nm) radiance as viewed by the eye should be limited to: T EXAX = 600/a 770 (5) for extended duration viewing conditions. This limit is based upon a 7 mm pupil diameter. 91 I I ft * . ; 4-y SC 16307 I________ x LAM025110 1 r* f. i )" \ a- if, I 4 This information supplied by industrial Hygiene Sectior. Dept, of KAed A Fm'ircn Nealf*" Monsanto Company St LOUIS. Mo. SC 16308 LAM025117 have carcinogenic potential without an assigned TLV: 4-Aminodiphenyl (p-Xenylamine) Benzidine production beta-Naphthylamine 4-Nitrodiphenyl 1c. Human Carcinogens. Substances with recognized carcinogenic potential awaiting reassignment of TLV pending further data acquisition: Vinyl chloride For the substances in 1b. no exposure or contact by any route -- respiratory, skin or oral, as de tected by the most sensitive methods -- shall be permitted. "No exposure or contact" means hermitizing the process or operation by the best practicable engi neering methods. The worker should be properly equipped to insure virtually no contact with the carcinogen. A2. industrial Substances Suspect of Carcinogenic Po tential for MAN. Chemical substances or sub stances associated with industrial processes, which are suspect of inducing cancer, based on either (1) limited epidemiologic evidence, exclusive of clinical reports of single cases, or (2) demon stration of carcinogenesis in one or more animal species by appropriate methods. Antimony trioxide production* Benzene -- Skin Benz(a)pyrene Beryllium Cadmium oxide production Chloroform Chromates of lead and zinc (as Cr) 3. 3'-Oichlorobenzidine Oimethylcarbamyl chloride 0.05 mg/m3 uppm 2.0 piS/m3 0.05 mg/m3 10 ppm 0.05 mg/m3 `Cigarette smoking can enhance the incidence of respiratory cancers from this or others of these substances or processes. 38 1,1-Dimethyl hydrazine Dimethyl sulfate Epichlorhydrin Hexamethyl phosphoramide -- Skin Hydrazine 4, 4'-Methylene bis (2-chloroaniline) -- Skin 4,4'-Methylene dianiline Monomethyl hydrazine Nitrosamines Propane sultone beta-Propiolactone Vinyl cyclohexene dioxide 0.5 ppm 1 ppm 5 ppm 0.1 ppm 0.02 ppm 0.2 ppm 10 ppm For the above, worker exposure by all routes should be carefully controlled to levels consistent with the animal and human experience data (see Documentation), including those substances with a listed TLV. A3. Guidelines for the Classification of Elemental ANIMAL Carcinogens- The following guidelines are offered in the present state of knowledge as an aid in classifying substances in the occupational envi ronment found to be carcinogenic in experimental animals. A need was felt by the Threshold Limits Committee for such a classification in order to take the first step in developing an appropriate TLV for occupational exposure. Determination of Approximate Threshold of Re sponse Requirement. In order to determine in which categoiy to classify an experimental carcin ogen lor the purpose of assigning an industrial air limit (TLV), an approximate threshold of neoplastic response must be determined. Because of practi cal experimental difficulties, a precisely defined threshold cannot be attained. For the purposes of standard-setting, this is of little moment, as an ap propriate risk, or safety, factor can be applied to the approximate threshold, the magnitude of which 1! '. * ; >n iPr !i II !i SC 16309 LAM025112 is dependent on the degree of potency of the car cinogenic response. To obtain the best 'practical' threshold of neoplas tic response, dosage decrements should be less than logarithmic. This becomes particularly impor tant at levels greater than 10 ppm (or correspond ing mg/m3). Accordingly, after a range-finding de termination has been made by logarithmic decreases, two additional dosage levels are re quired within the levels of "effect" and "no effect" to approximate the true threshold of neoplastic re sponse. The second step should attempt to establish a me tabolic relationship between animal and man for the particular substance found carcinogenic in an imals. (f the metabolic pathways are found compa rable, the substance should be classed highly sus pect as a carcinogen for man. If no such relation is found, the substance should remain listed as an experimental animal carcinogen until evidence to the contrary is found. Proposed Classification of Experimental Animal Carcinogens. Substances occurring in the occupa tional environment found carcinogenic for animals may be grouped into three classes, those of high, intermediate and low potency. In evaluating the in cidence of animal cancers, significant incidence of cancer is defined as a neoplastic response which represents, in the judgment of the Committee, a significant excess of cancers above that occurring in negative controls. EXCEPTIONS: No substance is to be considered an occupational carcinogen of any practical signifi cance which reacts by the respiratory route at or above 1000 mg/m3 for the mouse, 2000 mg/m3 for the rat; by the dermal route, at or above 1500 mg/kg for the mouse, 3000 mg/kg for the rat; by the gastrointestinal route at or above 500 mg/kg/d for a lifetime, equivalent to about 100 g T.O. for the rat, lOg T.D. for the mouse. 40 These dosage limitations exclude such substances as dioxane and trichlorethylene from consideration as carcinogens. Examples: Dioxane -- rats, hepatocellular and nasal tumors from 1015 mg/kg/d, oral Trichloroethylene -- female mice, tumors (30/98 @ 900 mg/kg/d), oral A3a. INDUSTRIAL SUBSTANCES OF HIGH CARCINO GENIC POTENCY IN EXPERIMENTAL ANIMALS 1. A substance to qualify as a carcinogen of high potency must fulfill one of the three following conditions in two animal species: la. Respiratory. Bicit cancer from (1) dosages below 1 mg/m3 (or equivalent ppm) via the respiratory tract in 6- 7-hour daily repeated inhalation exposures throughout lifetime; or (2) from a single intratracheally admin istered dose not exceeding 1 mg of parti culate, or liquid, per 100 ml or less of an imal minute respiratory volume; Examples: bis-Chlorom ethyl ether, malign ant tumors, rats, @ 0.47 mg/m3 (0.1 ppm) in 2 years; Hexamethyl phosphoramide, nasal squamous cell carcino ma, rats, @ 0.05 ppm, in 13 months OR lb. Dermal. Elicit cancer within 20 weeks by skin-painting, twice weekly at 2 mg/kg body weight or less per application for a total dose equal to or less than 1.5 mg, in a biologically inert vehicle; Examples: 7, 12-Dimethylbenz(a)anthracene -- skin tumors @ 0.120.8 mg T.D. in four weeks 41 sc 16310 LAM02511 Benz(a)pyrene, mice 12 p.g, 3X/wk for 18 mos. T.D. 2.6 mg, 90.9% skin tumors OR 1c. Gastrointestinal. Elicit cancer by daily in take via the gastrointestinal tract, within six months, with a six-month holding period, at a dosage below 1 mg/kg body weight per day; total dose, rat, < 50 mg; mouse, < 3.5 mg; Examples: 7, 12-Dimethylbenz(a)anthracene -- mammary tumors from 10 mg IX 3-Methylcholanthrene -- Tumors @ 3 sites from 8 mg in 89 weeks Benz(a)pyrene, mice. 3.9% leukemias, from 30 mg T.D. 198 days 2. Elicit cancer by all three routes in at least two animal species at dose levels prescribed for high or intermediate potency. A3b. INDUSTRIAL SUBSTANCES OF INTERMEDIATE CARCINOGENIC POTENCY IN EXPERIMENTAL AN IMALS To qualify as a carcinogen of intermediate potency, a substance should elicit cancer in two animal spe cies at dosages intermediate between those de scribed in A3a and A3c by two routes of adminis tration. Example: Carbamic acid Ethyl Ester Dermal, mammary tumors, mice, 100%, 63 weeks, 500-1400 mg T.D. Gastrointestinal, various type tumors, mice 42 weeks, 320 mg T.D. Gastrointestinal, various type tumors, rats, 60 weeks, 110-930 mg T.D. 42 A3c. INDUSTRIAL SUBSTANCES OF LOW CARCINO GENIC POTENCY IN EXPERIMENTAL ANIMALS To qualify as a carcinogen of low potency, a sub stance should elicit cancer in one animal species by any one of three routes of administration at the following prescribed dosages and conditions: la. Respiratory. Elicit cancer from (1) dosages greater than 10 mg/m3 (or equivalent ppm) via the respiratory tract in 6- 7-hour, daily re peated inhalation exposures, for 12 months' exposure and 12 months' observation period; or (2) from intratracheally administered dos ages totaling more than 10 mg of particulate or liquid per 100 ml or more of animal minute respiratory volume; Examples: Beryl (beryllium aluminum silicate) malig. lung tumors, rats, @ 15 mg/m3 @ 17 months Benzidine, var. tumors, rats, 10-20 mg/m3 @ > 13 mos. OR lb. Dermal. Elicit cancer by skin-painting of mice in twice weekly dosages of > 10 mg/kg body weight in a biologically inert vehicle for at least 75 weeks, i.e., a 1.5g T.D. Examples: Shale tar, mouse, 0.1 ml x 50 g T.D. 59/60 skin tumors Arsenic trioxide, man, dose un known, but estimated to be high lc. Gastrointestinal. Elicit cancer from daily oral dosages of 50 mg/kg/day or greater during the lifetime of the animal. APPENDIX B SUBSTANCES OF VARIABLE COMPOSITION B1 Polytetrafluoroethylene"' decomposition products. Thermal decomposition of the fluorocarbon chain in Tfade Names: Algoflon. Fluon. Halon. Teflon. Telran. 43 I 16311 t LAM025114 air leads to the formation of oxidized products con taining carbon, fluorine and oxygen. Because these products decompose in part by hydrolysis in alkaline solution, they can be quantitatively determined in air as fluoride to provide an index of exposure. No TLV is recommended pending determination of the toxi city of the products, but air concentrations should be minimal. B2 Gasoline. The composition of gasoline varies greatly and thus a single TLV for all types of these materials is no longer applicable. In general, the aromatic hy drocarbon content will determine what TLV applies. Consequently the content of benzene, other aromat ics and additives should be determined to arrive at the appropriate TLV (Elkins, et al. A.I.H.A.J. 24:99, 1963); Runion, ibid. 36.338,1975). 33 Welding Fumes -- Total Particulate (NOCr TLV. 5 mg/m3 Welding fumes cannot be classified simply. The com position and quantity of both are dependent on the alloy being welded and the process and electrodes used. Reli able analysis of fumes cannot be made without consider ing the nature of the welding process and system being examined; reactive metals and alloys such as aluminum and titanium are arc-welded in a protective, inert atmo sphere such as argon. These arcs create relatively little fume, but an intense radiation which can produce ozone. Similar processes are used to arc-weld steels, also creating a relatively low level of fumes. Ferrous alloys aiso are arc-welded in oxidizing environments which generate considerable fume, and can produce carbon monoxide instead of ozone. Such fumes generally are composed of discreet particles of amorphous slags con taining iron, manganese, silicon and other metallic con stituents depending on the alloy system involved. Chro mium and nickel compounds are found in fumes when stainless steels are arc-welded. Some coated and fluxcored electrodes are formulated with fluorides and the "Not otherwise classified. 44V fumes associated with them can contain significantly more fluorides than oxides. Because of the above fac tors, arc-welding fumes frequently must be tested for individual constituents which are likely to be present to determine whether specific TLVs are exceeded. Conclu sions based on total fume concentration are generally adequate if no toxic elements are present in welding rod, metal, or metal coating and conditions are not conducive to the formation of toxic gases. Most welding, even with primitive ventilation, does not produce exposures inside the welding helmet above 5 mg/m3. That which does, should be controlled. APPENDIX C MIXTURES C.1 THRESHOLD LIMIT VALUES FOR MIXTURES When two or more hazardous substances are pres ent, their combined effect, rather than that of either indi vidually, should be given primary consideration. In the absence of information to the contrary, the effects of the different hazards should be considered as additive. That is, if the sum of the following fractions. exceeds unity, then the threshold limit of the mixture should be considered as being exceeded. Ci indicates the observed atmospheric concentration, and T, the cor responding threshold limit (See Example lA.a. and 1A.c.). Exceptions to the above rule may be made when there is a good reason to believe that the chief effects of the different harmful substances are not in fact additive, but independent as when purely local effects on different organs of the body are produced by the various compo nents of the mixture. In such cases the threshold limit ordinarily is exceeded only when at least one member of (c c \y!- + or + -y? etc.) itself has a value exceeding unity (See Example 1A.c.). 45 SC 16312 V LAM025115 Antagonistic action or potentiation may occur with some combinations of atmospheric contaminants. Such cases at present must be determined individually. Poten tiating or antagonistic agents are not necessarily harmful by themselves. Potentiating effects of exposure to such agents by routes other than that of inhalation is also possible, e.g. imbibed alcohol and inhaled narcotic (trichloroethylene). Potentiation is characteristically exhibited at high concentrations, less probably at low. When a given operation or process characteristically emits a number of harmful dusts, fumes, vapors or gases, it will frequently be only feasible to attempt to evaluate the hazard by measurement of a single sub stance. In such cases, the threshold limit used for this substance should be reduced by a suitable factor, the magnitude of which will depend on the number, toxicity and relative quantity of the other contaminants ordinarily present. Examples of processes which are typically associated with two or more harmful atmospheric contaminants are welding, automobile repair, blasting, painting, lacquer ing, certain foundry operations, diesel exhauts, etc. C.1A Examples of THRESHOID LIMIT VALUES FOR MIXTURES The following formulae apply only when the compo nents in a mixture have similar toxicologic effects; they should not be used for mixtures with widely differing reactivities, e.g. hydrogen cyanide & sulfur dioxide. In such case the formula for Independent Effects (lA.c.) should be used. lA.a. General case, where air is analyzed for each com ponent: a. Additive effects. (Note: It is essential that the atmosphere be analyzed both qualitatively and quantitatively for each component present, in order to evaluate compliance or noncom pliance with this calculated TLV.) s I 'J '1 , ) 46 Example No. 1A.a.: Air contains 5 ppm of carbontetrachloride (TLV = 10 ppm) 20 ppm of 1, 2-dichloroethane (TLV = 50 ppm) and 10 ppm of 1, 2-dibromoethane (TLV = 20 ppm) Atmospheric concentration of mix ture = 5 + 20 + 10 = 35 ppm of mixture 5 , 20 , 10 10 50 20 25 + 20 + 25 , , 50 1 4 Threshold Limit is exceeded. Furthurmore, the TLV of this mixture may be calculated by reducing the total fraction to 1.0; i.e. 35 TLV of mixture = -^-= 25 ppm lA.b. Special case when the source of contaminant is a liquid mixture and the atmospheric composition is assumed to be similar to that of the original mate rial; e.g. on a time-weighted average exposure basis, all of the liquid (solvent) mixture eventually evaporates. Additive effects (approximate solution) 1. The percent composition (by weight) of the liquid mixture is known, the TLVs of the constituents must be listed in mg/m3. (Note: In order to evaluate compliance with this TLV, field sampling instwments should be calibrated, in the laboratory, for response to this specific quantitative and qualitative airvapor mixture, and also to fractional concen trations of this mixture; e.g., 112 the TLV; 1110 the TLV; 2 x the TLV; 10 x the TLV; etc.) TLV of mixture = 1 _jp-- + _ + _k_ + TLV,, TLVt TLVC ' '' TLV, 47 sc 16313 LAM025116 Example No. 1: Liquid contains (by weight) 50% heptane: TLV = 400 ppm or 1600 mg/m3 1 mg/m3 e 0.25 ppm 30% methylene chloride: TLV = 200 ppm or 720 mg/m3 1 mg/m3 0.28 ppm 20% perchloroethylene: TLV = 100 ppm or 670 mg/m3 1 mg/m3 a 0.15 ppm TLV of Mixture = ^ ~ ^ 1600 + 720 + 670 1 0.00031 + 0.00042 + 0.00030 = 0.00103 = 970 m9/m3 of this mixture 50% or (970) (0.5) = 485 mg/m3 is heptane 30% or (970) (0.3) = 291 mg/m3 is methylene chloride 20% or (970) (0.2) = 194 mg/m3 is perchloroethylene These values can be converted to ppm as follows: heptane: 485 mg/m3 x 0.25 = 121 ppm methylene chloride: 291 mg/m3 x 0.28 = 81 ppm perchloroethylene: 194 mg/m3 x 0.15 = 29 ppm TLV of mixture = 121 + 81 + 29 = 231 ppm, or 970 mg/m3 lA.c. Independent effects. Air contains 0.15 mg/m3 of lead (TLV, 0.15) and 0.7 mg/m3 of sulfuric acid (TLV, 1). Threshold limit is not exceeded. IB. TLV for Mixtures of Mineral Ousts. For mixtures of biologically active mineral dusts the general formula for mixtures may be used. 48 For mixture containing 80% nonasbestiform talc and 20% quartz, the TLV for 100% of the mixture is given by: TLV = ------= 9 mppcf 0.8 0.2 20 2.7 TLV of nonasbestiform talc (pure) = 20 mppcf TLV of quartz (pure) = --300 = = 2.7 mppcf 100 + 10 110 w Essentially the same result will be obtained if the limit of the more (most) toxic component is used provided the effects are additive. In the above ex ample the limit for 20% quartz is 10 mppcf. For another mixture of 25% quartz, 25% amor phous silica and 50% talc: 25% quartz -- TLV (pure) = 2.7 mppcf 25% amorphous silica -- TLV (pure) = mppcf 50% talc TLV (pure) = 20 mppcf TLV = 0.25 2.7 1 0.25 20 = 8 mppcf 0.5 20 The limit for 25% quartz approximates 9 mppcf. APPENDIX D PERMISSIBLE EXCURSIONS FOR TIME- WEIGHTED AVERAGE (TWA) LIMITS The Excursion TLV Factor in the Table automatically defines the magnitude of the permissible excursion above the limit for those substances not given a "C" designation; i.e., the TWA limits. Examples in the Table show that nitrobenzene, the TLV for which is 1 ppm, should never be allowed to exceed 3 ppm. Similarly, carbon tetrachloride, TLV = 10 ppm, should never be allowed to exceed 20 ppm. By contrast, those sub stances with a "C" designation are not subject to the excursion factor and must be kept at or below the TLV ceiling. 49 sc 16314 LAM025117 These limiting excursions are to be considered tc provide a "rule-of-thumb" guidance for listed sub stances generally, and may not provide the most appro priate excursion for a particular substance e.g., the per missible excursion for CO is 400 ppm for 15 minutes. For appropriate excursions for 142 substances con sult Pa. Rules & Regs., Chap. 4, Aft. 432, and "Accept able Concentrations," ANSI. Substance Nitrobenzene Carbon tetrachloride Trimethyl benzene Acetone Boron trifluoride Butylamine TLV 1 10 25 1000 Cl C5 Excursion Factor 3 2 1.5 1.25 Max. Cone. Permitted for short time 3 20 40 1250 1 5 tlie question of interpretation of essentially "instanta neous" peaks arises. Although no general statement can be made covering all occupational substances, the fol lowing guidelines should prove helpful, assuming peak excursions conform to time-weighted average TLV as stated above. The toxicologic importance of momentary peak con centrations depends on whether the substance is fast or slow acting. If slow acting, as for quartz, lead, or car bon monoxide, momentary peaks are of no toxicologic concern provided, of course, they are not astronomic. On the other hand, fast-acting substances that rapidly produce disabling narcosis, e.g., H2S, or intolerable irri tation or asphyxiation, NHa. S02, C02, or initiate sensitiza tion-- the organic isocyanates, even "instantaneous" peaks appreciably above the permissible excursion, should not be permitted, unless information exists to the contrary. Other more specific excursions will be devel oped in the future. EXCURSION FACTORS For all substances not bearing C notation TLV>0-1 (ppm or mg/m3). TLV>1-10 TLV>10-100 TLV>100-1000 UAFla/UctOolrUtl The number of times the excursion above the T permitted is governed by conformity with the 1 Weighted Average TLV. initHt'HETATION OF MEASURED PEAK CONCENTRATIONS With increasing use of rapid, direct-reading analytii instruments for airborne contaminants in the work are 50 APPENDIX E Some Nuisance Particulates"* TLV, 30 mppcf or 10mg/m3 Alundum (Al202) Calcium carbonate Calcium silicate Cellulose (paper fiber) Portland Cement Corundum (Al20a) Emery Glass, fibrousrtor dust Glycerin Mist Graphite (synthetic) Gypsum Vegetable oil mists (except castor, cashew nut, or similar irritant oils) Kaolin Limestone Magnesite Marble Mineral Wool Fiber Pentaerythritol Plaster of Paris Rouge Silicon Silicon Carbide Starch Sucrose Tin Oxide Titanium Dioxide Zinc Stearate Zinc oxide dust 51 SC 16315 LAM025 7 q) When toxic impurities are not present, e.g. quartz < 1%.. r) <7^xm in diameter APPENDIX F Some Simple Asphyxiants11 Acetylene Argon Butane Ethane Ethylene Helium Hydrogen Methane Neon Propane Propylene s) As defined on pg. 6. APPENDIX G Calculations for Conversion of Particle Count Concen tration (by Standard Light Field -- Midget Impinger Techniques), in mppcf, to Respirable Mass Concentra tion (by Respirable Sampler) in mg/m3./- 1. In 1967, Jacobsen and Tomb.t derived an empiri cal relationship of 5.6 mppcf to 1 milligram of respirable dust per cubic meter of air, based on 23 sets of samples, mostly coal dust. The follow ing calculation results in an equivalence of 6.37 mppcf to 1 mg/m3 of respirable dust. Thus, an approximate ratio of 6 mppcf to 1 mg/m3 of re spirable dust is suggested for conversion of TLVs from a count to a mass basis when the density and mass median diameter have not been deter mined. -"Relationship Between Gravimetric Respirable Oust Concentration and Midget Impinger Number Concentration." by Murray Jacobson and T. F. Tomb. AIHAJ, 28: Nov.-Oec. 1967. 52 2. Basic assumptions: a) Average density for silica containing dusts <* 2.5 gms/cm3 (2500 mg/cm3). Pulmonary sig nificant dust densities may vary from 1.2 gm/cm3 for coal dust to 3.1 gms/cm3 for Portland Cement. Silica densities vary from 2.2 (amorphous) to 2.3 (cristobaiite and tridymite) to 2.5 (alpha-quartz.) gms per cm3. b) The mass median diameter (mmd) of particles collected in midget impinger samplers and counted by the standard light field technique, and collected in a respirable sampler is ap proximately 1.5 fisn or 1.5 x 10~ cm. This assumption is, of course, quite arbitrary since the mmd of all dust clouds is quite variable, depending on many independent parameters, such as source of dust, age of dust cloud, me teorological conditions, etc. 3. Calculation: a) vol. per particle: 4/3 n r3; r = 0.75 x 10-4 cm = 4/3 it (0.75 x 10-*)3 = 1.77 x 10-'2 cm3 b) wt. per particle = vol. x density = 1.77 x 10~12 cm3 x 2.5 x 103 mg/cm3 = 4.425 x 10- mg/particle c) 1 particle/ft.3 = 35.5 part,/m3 (since 35.5 cu ft = 1 cu m.) 10s part./ft3 = mppcf = 35.5 x 10s part./m3 wt. of 1 mppcf = 35.5 x 10s part./m3 x 4.425 x 10-* mg/part. 1 mppcf m 0.157 mg/m3 or 6.37 mppcf 1 mg/m3 or approximately 6 mpccf = t mg/m3. 4.Equivalent TLVs in mppcf and mg/m3 (respirable mass) for Mineral Dusts. 53 *1 1 |l I I !i SC 16316 l______ , LAM025119 Substance Threshold Limit Value Count Resp. Mass Total Mass* mppcf mg/m3 mg/m3 Silica (SiOi) Amorphous Cristobalite Fused silica Quartz Tridymite Coal Oust Diatomaceous earth, natural Graphite Mica Mineral wool fiber Nuisance particulates Perlite Portland Cement Soapstone Talc (nonasbestiform) Tripoli 20 1.5 3 3 1.5 (12) -- 15 20 -- 30 30 30 20 20 (3) (3)** 0.05 0.1 0.1 0.05 2 1.5 (2.5) (3) (5) (5) (5) (5) (3) (3) 0.1 (6) 0.15 0.3 0.3 0.15 (4) (5) (6) 10 10 (10) (10) (6) (6) (0.3) TLVs Threshold Limit Values for Physical Agents Adopted by ACGIH for 1977 'Unless otherwise specified, respirable mass is presumed to equal ap proximately 50% of total mass. "AH values in parentheses () represent newly calculated values based on equivalence of mppcf 1 mg/m> respirable mass and respirable mass m 50% total mass. 54 Sc 16317 LAM025120 1977 TLV PHYSICAL AGENTS COMMITTEE Herbert H. Jones, Central Missouri State University, Chairman Peter A. Breysse, University of Washington Gerald V. Coles, United Kingdom Thomas Cummings, Ontario Dept, of Health Irving H. Davis, Michigan Dept, of Health Ronald D. Dobbin, NIOSH LCDR Joseph J. Drozd. USN Maj. George S. Kush, USAF Edward J. Largent, OSHA William E. Murrey, NIOSH Dr. Wordie H. Parr, NIOSH David H. Sliney, USAEHA Lt. Col. Robert T. Wangemann, USAEHA Thomas K. Wilkinson, USPHS-NIH Any comments or questions regarding these limits should be addressed to: Secretary-Treasurer P.O. Box 1937 Cincinnati, Ohio 45201 PREFACE PHYSICAL AGENTS These threshold limit values refer to levels of physical agents and represent conditions under which it is be lieved that nearly all workers may be repeatedly exposed day after day without adverse effect. Because of wide variations in individual susceptibility, exposure of an oc casional individual at, or even below, the threshold limit may not prevent annoyance, aggravation of a pre-exist ing condition, or physiological damage. These threshold limits are based on the best available information from industrial experience, from experimen tal human and animal studies, and when possible, from a combination of the three. These limits are intended for use in the practice of industrial hygiene and should be interpreted and applied only by a person trained in this discipline. They are not intended for use, or for modification for use, (1) in the evaluation or control of the levels of physical agents in the community, (2) as proof or disproof of an existing physical disability, or (3) for adoption by countries whose working conditions differ from those in the United States of America. These values are reviewed annually by the Committee on Threshold Limits for Physical Agents for revisions or additions, as further information becomes available. Notice of Intent--At the beginning of each year, proposed actions of the Committee for the forthcoming year are issued in the form of a "Notice of Intent." This notice provides not only an opportunity for comment, but solicits suggestions of physical agents to be added to the list. The suggestions should be accompanied by substantiating evidence. As Legislative Code -- The Conference recognizes that the Threshold Limit Values may be adopted in legis lative codes and regulations. If so used, the intent of the concepts contained in the Preface should be maintained and provisions should be made to keep the list current. 57 "1 i US I SC 16318 LAM025727 $k >H*2SBE Reprint Permission -- This publication may be re printed provided that written permission is obtained from the Secretary-Treasurer of the Conference and that this Preface be published in its entirety along with the Threshold Limit Values. THRESHOLD UMIT VALUES HEAT STRESS These Threshold Limit Values refer to heat stress conditions under which it is believed that nearly all workers may be repeatedly exposed without adverse health effects. The TLVs shown in Table 1 are based on the assumption that nearly all acclimatized, fully clothed workers with adequate water and salt intake should be able to function effectively under the given working con ditions without exceeding a deep body temperature of 38X (WHO technical report series #412, 1969 Health Factors Involved in Working Under Conditions of Heat Stress-, F. N. Dukes-Dobos and A. Henschel: "Develop ment of Permissible Heat Exposure Limits lor Occupa tional Work." ASHRAE Journal, Vol. 15: No. 9, Sep tember 1973, pp. 57-62.) Since measurement of deep body temperature is im practical for monitoring the workers' heat load, the mea surement of environmental factors is required which most nearly correlate with deep body temperature and other physiological responses to heat. At the present time Wet Bulb-Globe Temperature Index (WBGT) is the simplest and most suitable technique to measure the en vironmental factors. WBGT values are calculated by the following equations: 1. Outdoors with solar load: WBGT = 0.7WB + 0.2GT + 0.1 DB 2. Indoors or Outdoors with no solar lead: WBGT =0.7WB +0.3GT where: WBGT = Wet Bulb-Globe Temperature Index WB = Natural Wet-Bulb Temperature DB = Dry-Bulb Temperature GT = Globe Thermometer Temperature 58 The determination of WBGT requires the use of a black globe thermometer, a natural (static) wet-bulb thermom eter, and a dry-bulb thermometer. TABLE 1 Permissible Heat Exposure Threshold Limit Values - _ r_ or* tirof* TV Work -- Rest Regimen Continuous work Work Load Light Moderate Heavy 30.0 26.7 25.0 75% Work -- 25% Rest, Each hour 30.6 28.0 25.9 50% Work -- 50% Rest, Each hour 31.4 29.4 27.9 25% Work -- 75% Rest, Each hour 32.2 31.1 30.0 Higher heat exposures man smmii m lauic i uib pwi missible if the workers have been undergoing medical surveillance and it has been established that they are more tolerant to work in heat than the average worker. Workers should not be permitted to continue their work when their deep body temperature exceeds 38.0X. APPENDIX G HEAT STRESS I. Measurement of the Environment The instruments required are a dry-bulb, a natural wet-bulb, a globe thermometer, and a stand. The mea surement of the environmental factors shall be per formed as follows: A. The range of the dry and the natural wet bulb ther mometer shall be -5X to 50X with an accuracy of 0.5X. The dry bulb thermometer must be shielded 59 i SC 16319 V____ JL. LAM025122 from the sun and the other radiant surfaces of the envi ronment without restricting the airflow around the bulb. The wick of the natural wet-bulb thermometer shall be kept wet with distilled water for at least 1/2 hour before the temperature reading is made. It is not enough to immerse the other end of the wick into a reservoir of distilled water and wait until the whole wide becomes wet by capillarity. The wick shall be wetted by direct application of water from a syringe 1/2 hour before each reading. The wick shall extend over the bulb of the ther mometer, covering the stem about one additional bulb length. The wick should always be clean and new wicks should be washed before using. B. A globe thermometer, consisting of a 15 cm. (6inch) diameter hollow copper sphere, painted on the outside with a matte black finish or equivalent shall be used. The bulb or sensor of a thermometer (range -5C to 100C with an accuracy of 0.5aC) must be fixed in the center of the sphere. The globe thermometer shall be exposed at least 25 minutes before it is read. C. A stand shall be used to suspend the three thermom eters so that they do not restrict free air flow around the bulbs, and the wet-bulb and globe thermometers are not shaded. D. It is permissible to use any other type of temperature . sensor that gives identical reading to a mercury ther mometer under the same conditions. E. The thermometers must be so placed that the read ings are representative of the condition where the men work or rest, respectively. The methodology outlined above is more fully ex plained in the following publications: 1. "Prevention of Heat Casualties in Marine Corps Re cruits, 1955-1960, with Comparative Incidence Rates and Climatic Heat Stresses in other Training Cate gories," by Captain David Minard, MC, USN, Research Report No. 4, Contract No. MR0Q5.01-C0Q1.Q1, Naval Medical Research Institute, Bethesda, Maryland, 21 Feb ruary 1961. 2. "Heat Casualties in the Navy and Marine Corps, 60 1959-1962, with Appendices on the Field Use of the Wet Bulb-Globe Temperature Index," by Captain David Minard. MC, USN, and R. L. O'Brien, HMC, USN. Re search Report No. 7, Contract No. MR 005.01-0001.01. Naval Medical Research Institute, Bethesda, Maryland, 12 March 1964. 3. Minard, D.: Prevention of Heat Casualties in Marine Corps Recruits. Military Medicine 126(4): 261-272, 1961. II.Work Load Categories Heat produced by the body and the environmental heat together determine the total heat load. Therefore, if work is to be performed under hot environmental condi tions, the workload category of each job shall be es tablished and the heat exposure limit pertinent to the work load evaluated against the applicable standard in order to protect the worker from exposure beyond the permissible limit. A. The work load category may be established by rank ing each job into light, medium, and heavy categories on the basis of type of operation. Where the work load is ranked into one of said three categories, i.e. (1) light work (up to 200 Kcal/hr or 800 Btu/hr): e.g., sitting or standing to control machines, performing light hand or arm work, (2) moderate work (200-350 Kcal/hr or 600-1400 Btu/hr): e.g., walking about with moderate lifting and pushing, (3) heavy work (350-500 Kcal/hr or 1400-2000 Btu/hr): e.g., pick and shovel work, the permissible heat exposure limit for that work load shall be determined from Table 1. B. The ranking of the job may be performed either by measuring the worker's metabolic rate while performing his job or by estimating his metabolic rate by the use of the scheme shown in Table 2. Tables available in the literature listed below and in other publications as well may also be utilized. When this method is used the per missible heat exposure limit can be determined by Figure 61 16320 LAM025123 _ - - ......................:_________________- _______________________ _____ 1. Per-Olaf Astrand and Kaare Rodahl: "Textbook of Woik Physiology" McGraw-Hill Book Company, New York, San Francisco, 1970. 2. "Ergonomies Guide to Assessment of Metabolic and Cardiac Costs of Physical Work." Amer. Ind. Hyg. Assoc. J. 32:560,1971. 3. Energy Requirements for Physical Work. Purdue Farm Cardiac Project. Agricultural Experiment Station. Research Progress Report No. 30,1961. 4. J. V. G. A. Durnin and R. Passmore: "Energy, Work and Leisure." Heinemann Educational Books, Ltd., Lon don, 1967. Light hand work: writing, hand knitting Heavy hand work: typewriting Heavy work with one arm: hammering in nails (shoe maker, upholsterer) Light work with two arms: filing metal, planing wood, raking of a garden Moderate work with the body: cleaning a floor, beat ing a carpet Heavy work with the body: railroad track laying, dig ging, barking trees TABLE 2 Assessment of Work Load Average values of metabolic rate during different tivities. ac- A. Body position and movement Sitting Kcal./min. Standing Walking 0.3 0.6 Walking up hill 2.0-3.0 add 0.6 per meter (yard) rise B. Type of Work Average Range Kcal./min. Kcal./min. Hand work light heavy Work with one arm 0.4 0.9 0.2-1.2 light heavy Work with both arms 1.0 1.8 0.7-2.5 Work with body light heavy 1.5 2.5 1.0-3.5 light moderate heavy very heavy 3.5 5.0 7.0 9.0 2.5-15.0 Sample Calculation: Using a heavy hand tool on an assembly line A. Walking along 2.0 Kcal./min. B. Intermediate value between heavy work with two arms and light work with the body 3.0 Kcal./min. C. Add for basal metabolism 5.0 Kcal./min. 1.0 Kcal./min. Total 6.0 Kcal./min. Adapted from Lehmann, G. E., A. Muller and H. Spitzer. Der Kalorienbedarf bei gewerblicher Arbeit Arbeitsphysiol. 14:166,1950. III. Work-Rest Regimen The permissible exposure limits specified in Table 1 and Figure 1 are based on the assumption that the WBGT value of the resting place is the same or veiy close to that of the work place. Where the WBGT of the work area is different from that of the rest area a timeweighted average value should be used for both environ mental and metabolic heat. When time-weighted average values are used the appropriate curve on Figure 1 is the solid line labeled "continuous." The time-weighted average metabolic rate (M) shall be determined by the equation: Av. M = (Mi) x (ti) + (Ma) x (tz) +,... + (MJ x (t,,) (tl) + (t2) +....+ (tj 62 63 ___________ _________________ SC 16321 L LAM025124 Where Mi Mi, M, are estimated or measured metabolic periods where the workers' hourly average metabolic rates for the various activities of the worker during the rate will be higher. total time period, ti, tz t, are the elapsed times in min utes spent at the corresponding metabolic rate as deter IV. Water and Salt Supplementation mined by a time study. During the hot season or when the worker is exposed The time-weighted average WBGT shall be deter to artificially generated heat, drinking water shall be mined by the equation: made available to the workers in such a way that they Av. WBGT = are stimulated to frequently drink small amounts, i.e., (WBGTi) x (ti) + (WBGTz} xtz +... + (WBGT.) x (tJ one cup every 15-20 minutes (about 150 ml or 1/4 (ti) + (tz) + ... + (t,,) where WBGTi, WBGTz WBGT. are calculated values of WBGT for the various work and rest areas occupied dur ing total time periods, ti, tz t.are the elapsed times in minutes spent in the corresponding areas which are de pint). The water shall be kept reasonably coot (10o-15C or 50.0-60.0F) and shall be placed close to the work place so that the worker can reach it without abandoning the work area. termined by a time study. Where exposure to hot envi The workers should be encouraged to salt their food ronmental conditions is continuous for several hours or abundantly during the hot season and particularly during the entire work day, the time-weighted averages shall be hoi spells. If the workers are unacclimatized, salted calculated as hourly time-weighted average i.e., ti + b drinking water shall be made available in a concentration + ... t. = 60 minutes. Where the exposure is intermit of 0.1% (1g NaCI to 1.0 liter or 1 level tablespoon of salt I t tent, the time-weighted averages shall be calculated as to 15 quarts of water). The added salt shall be complete two-hour time-weighted averages, i.e., ti + tz + ,.. t. ly dissolved before the water is distributed, and the i = 120 minutes. water shall be kept reasonably cool. The permissible exposure limits for continuous work are applicable where there is a work-rest regimen of a 6-day work week and an 8-hour work day with a short V. Other Considerations A. Clothing: The permissible heat exposure TLVs are morning and afternoon break (approximately 15 min utes) and a longer lunch break (approximately 30 min valid for light summer clothing as customarily worn by workers when working under hot environmental condi utes). Higher exposure limits are permitted if additional tions. If special cothing is required for performing a par resting time is allowed. Ait breaks, including unsche ticular job and this clothing is heavier or it impedes I duled pauses and administrative or operational waiting sweat evaporation or has higher insulation value, the i i ! periods during work may be counted as rest time when additional rest allowance must be given because of high environmental temperatures. worker's heat tolerance is reduced, and the permissible heat exposure limits indicated in Table 1 and figure 1 are not applicable. For each job category where special clothing is required, the permissible heat exposure limit It is a common experience that when the work on a job is self-paced, the workers will spontaneously limit their hourly work load to 30-50% of their maximum physical performance capacity. They do this either by shall be established by an expert. B. Acclimatization and fitness: The recommended heat stress TLVs are valid for acclimated workers who are !h setting an appropriate work speed or by interspersing physically tit. unscheduled breaks. Thus the daily average of the workers' metabolic rate seldom exceeds 330 kcal/hr. However, within an 8-hour work shift there may be it 64 i i i SC 16322 LAM025125 BTU/hr Rote o( Work Figure 1 -- Permissible Heat Exposure Threshold Limit Value IONIZING RADIATION See U.S. Department of Commerce National Bureau of Standards, Handbook 59, "Permissible Dose from Ex ternal Sources of Ionizing Radition," September 24, 1954, and addendum of April 15, 1958. A report, Basic Radiation Protection Criteria, published by the National Committee on Radiation Protection, revises and modern izes the concept of the NCRP standards of 1954, 1957 and 1958; obtainable as NCRP Rept. No. 39, P. 0. Box 4867, Washington, D.C. 20008. LASERS The threshold limit values are for exposure to laser radiation under conditions to which nearly all workers may be exposed without adverse effects. The values 66 should be used as guides in the control of exposures and should not be regarded as fine lines between safe and dangerous levels. They are based on the best avail able information from experimental studies. Umiting Apertures The TLVs expressed as radiant exposure or irradiance in this section may be averaged over an aperture of 1 mm except for TLVs for the eye in the spectral range of 400-1400 nm, which should be averaged over a 7 mm limiting aperture (pupil); and except for all TLVs for wa velengths between 0.1-1 mm where the limiting aper ture is 10 mm. No modification of the TLVs is permitted for pupil sizes less than 7 mm. The TLVs for "extended sources" apply to sources which subtend an angle greater than a (Table 5) which varies with exposure rime. This angle is not the beam divergence of the source. Correction Factors A and B (CA and Ct) for Eye Expo sure All TLVs in Tables 3 and 4 are to be used as given for wavelengths 400 nm to 700 nm. At all wavelengths greater than 1.06 pm and less than 1.4 pm the TLVs are to be increased by a factor of 5. TLV at wavelengths between 700 nm and 1.06 pm are to be increased by a uniformly extrapolated factor as shown in Figure 2. For certain exposure durations at wavelengths between 700800 nm, correction factor C is applied. Repetitively Pulsed Lasers Since there are few experimental data for multiple pulses, caution must be used in the evaluation of such exposures. The protection standards for irradiance or ra diant exposure in multiple pulse trains have the following limitations; (1) The exposure from any single pulse in the train is limited to the protection standard for a single compara ble pulse. (2) The average irradiance for a group of pulses is limited to the protection standard as given in Tables 3, 4, or 6 of a single pulse of the same duration as the entire pulse group. 67 SC 16323 LAM025126 Correction Factor (3) When the Instantaneous Pulse Repetition Fre quency (PRF) of any pulses within a train exceeds one, the protection standard applicable to each pulse is re duced as shown in Figure 6 for pulse durations less than 10~s second. For pulses of greater duration, the follow ing formula should be followed: --ear)- where: Standard (pulse nr) n n = number of pulses in train r = duration of a single pulse in the train Standard (nr) = protection standard of one pulse having a duration equal to nr sec onds. Wov*lnglh |nm) Figure 2 -- TLV correction factors for laser wavelengths (eye). 68 SC 16324 T < -R Sb 5 TS e 69 fj LAM025127  70 SC 16325 t z-uo-n 3anSOdX3 XNVIOVM MX L_____ Jt_ LAW1025128 Figure 4a -- TLV for laser exposure of skin and eyes for far-infrared radiation (wavelengths greater than LAM025129 Figure 5a -- TLV for extended sources or diffuse reflections of laser radiation (400-700 nm). LAM025130 TABLE 3 Threshold Limit Value for Direct Ocular Exposures (Intrabeam Viewing) from a Laser Beam Exposure Time, 0(0 1000O0(O0(O0O0O0 o COCO^Oi-^-- c\l V <D r- w(D r- ?o Bc Bc GCOMO OCCMO O eeeeeeeeeeeeeee ccccccccccccccc oofo^tntONCooiO'-cvntv) OCMCCMOCOOCOOCOOCOOCOOCOOCOOC^O*C^O"C^O--COCTO-CYO-- ZD ZD Bo eo ( | t PSAs .s e 5-T 1-^. tw Eo E^o^l t0'x t o o X lO co T-* O_ CO. O - ,?-ow O to . ' lXOOw^CXONOJIrO- LO W- O oo OI oS . O W ^ T" CO _2_ xa2_s 0X2, oK o UJ -J O X CO 1-0^I ^ X? OO XOO V T- O Y- T- X y?K=2:22"sfl < folSIf CXXO 000 SI CxO .* TI e2? .I rf o O o o o O , -O 0.000000 3I 1 -< c ces _ c Ec cEeEeECE0E>E0>c0000ecei: oo O O O) O O O lO U*> ^ ^ > n SONOl^OONONONOr-1O- tQ-tQ-^o oooooooo^-*-oo E EEEEEEEE EEie oOoOoOolOoolOoOoOcoOcOoOoO**.: o 8 <> ZD <c CQ cc cc t *= >s c t8o 8 8 "T . I S| I < = " -- e" o 1= 8 -8 UONt-m Spectral 76 sc 16328 77 Ll LAIV1025131 TABLE 4 Threshold Limit Values (or Viewing a Diffuse Reflection iovt/)2NWCMW^0 CO so V co od*X Xo CO V- oo 2 ^ X ^ oco o ^ _X Oco' oo o2i OOOO "O o OO o eeeeeeIII CO oOcoOc^OcoOcoOcoOc^o0rOo^Oo^ECc OOOOO'OoOOo E E E E E E E E EE CC=C=CC=CCCC=^ OOOOOOtOOOiOOOOOOOOOm.. WO-,'5'lOlO^,NN^T" itS?r cos o 3 < to cc cc 78 3S i-- E CD e cciif>coc\i-:e\iejmT-c'jcM< s5 - l| < c/s ? Sftn <u CT uj " Sa < %'S 1= .is I >11 111 I I 4 ooooooooo -OOOO 79 sc 16329 LAM025132 MICROWAVES* bg These Threshold Limit Values refer to microwave en ergy in the frequency range of 100 MHz to 100 GHz and represent conditions under which it is believed that near ly all workers may be repeatedly exposal without ad verse effect. These values should be used as guides in the control of exposure of microwaves and should not be regarded as a fine line between safe and dangerous levels. TABLE 6 Threshold Limit Value for Skin Exposure from a Laser Beam -_M -O 7 I n X -5 J? ? tO" 2 ow . j 5 CO CM T-- CO g5 ow T3 a O3 oo sP c XI X 5<S> _To-T-oCO o I I I I *- O'--O O -o Iu _E CM e E E 3-JS w CO E C4 <D >h^- -0o3 H-. 10 *r c. .2 on V) 1e pE0> ,ue3.> oo CO o EE cc ooCM ooM : g "2 oC?L Si O ??, O o_O *9 _ -c < op ^ircc O CD O z Recommended Values The Threshold Limit Value for occupational mi crowave energy exposure where power densities are known and exposure time controlled is as follows: 1. For average power density levels up to but not ex ceeding 10 milliwatts per square centimeter, total ex posure time shall be limited to the 6-hour workday (continuous exposure). 2. For average power density levels from 10 milliwatts per square centimeter up to but not exceeding 25 milliwatts per square centimeter, total exposure time shall be limited to no more than 10 minutes for any 60 minute period during an 8-hour workday (inter mittent exposure). 3. For average power density levels in excess of 25 mil liwatts per square centimeter, exposure is not per missible. NOTE: For repetitively pulsed sources the average power density may be calculated by multiplying the peak power density by the duty cycle. The duty cycle is equal to the pulse duration in seconds times the pulse repetition rate in hertz. 'See Notice of intended Changes. Page 89; Notice of Intent to Study, page 94. NOISE These threshold limit values refer to sound pressure levels and durations of exposure that represent condi tions under which it is believed that nearly all workers may be repeatedly exposed without adverse effect on f tcf 80 81 > sc 16330 LAM025133 V f. * .i V': This information supplied by industrial Hygiene Section Dept, of t^ed & Environ Hea|ft Monsanto Company St LOUIS. Mo N* SC 16331 <s LAM025134 II their ability to hear and understand norma! speech. The Table 7 Threshold Limit Values medical profession has defined hearing impairment as Duration per day an average hearing threshold level in excess of 25 de Hours cibels (ANSI-S3.6-1969) at 500. 1000, and 2000 Hz. I and the limits which are given have been established to 16 prevent a hearing loss in excess of this level. The values 8 should be used as guides in the control of noise expo 4 sure and, due to individual susceptibility, should not be 2 regarded as fine lines between safe and dangerous 1 levels. 1/2 1/4 Sound Level dBA-' 80 85 90 95 100 105 110 Continuous or Intermittent 1/8 115* The sound level shall be determined by a sound level meter, conforming as a minimum to the requirements of the American National Standard Specification for Sound Level Meters, S1.4 (1971) Type S2A, and set to use the A-weighted network with slow meter response. Duration of exposure shall not exceed that shown in Table 7. These values apply to total duration of exposure per working day regardless of whether this is one continu ous exposure or a number of short-term exposures but does not apply to impact or impulsive type of noise. When the daily noise exposure is composed of two or more periods of noise exposure of different levels, their combined effect should be considered, rather than the individual effect of each. If the sum of the following fractions: Ci , Ca , C Tt Tt T. exceeds unity, then, the mixed exposure should be con sidered to exceed the threshold limit value, Ci indicates the total duration of exposure at a specific noise level, and Ti indicates the total duration of exposure permitted at that level. All on-the-job noise exposures of 80 dSA or greater shall be used in the above calculations. 'No exposure to continuous or intermittent in excess of 115 dBA a) Sound level in decibels as measured on a sound level meter, conforming as a minimum to the require ments of the American National Standard Specifica tion for Sound Level Meters, SI .4 (1971) Type S2A, and set to use the A-weighted network with slow meter response. IMPULSIVE OR IMPACT NOISE It is recommended that exposure to impulsive or im pact noise shall not exceed the limits listed in Table 8 or taken from Figure 7. No exposures in excess of 140 de cibels peak sound pressure level are permitted. Impul sive or impact noise is considered to be those variations in noise levels that involve maxima at intervals of greater than one per second. Where the intervals are less than one second, it should be considered continuous. Sound Level dB' 140 130 120 Table 8 Threshold Limit Values Impulsive or Impact Noise Permitted Number of Impulses or Impacts per day 100 1000 10,000 I 1 : ; l f I*' t i: 'It should be recognized that the applcation of the TLV for noise will not t protect all workers from the adverse effects of noise exposure. A hearing conservation program with audiometric testing is necessary when T l workers are exposed to noise at or above the TLV levels. ' 'Decibels peak sound pressure level. i l1 82 83 a jr SC 16332 L______ JL LAM025135 Figure 7 -- 84 sc 16333 ULTRAVIOLET RADIATION* These threshold limit values refer to ultraviolet radia tion in the spectral region between 200 and 400 nm and represent conditions under which it is believed that near ly all workers may be repeatedly exposed without ad verse effect. These values for exposure of the eye or the skin apply to ultraviolet radiation from arcs, gas, and vapor discharges, fluorescent, and incandescent sources, and solar radiation, but do not apply to ultravi olet lasers.* These levels should not be used for deter mining exposure of photosensitive individuals to ultravi olet radiation. These values should be used as guides in the control of exposure to continuous sources where the exposure duration shall not be less than 0.1 sec. These values should be used as guides in the control of exposure to ultraviolet sources and should not be re garded as a fine line between safe and dangerous levels. Recommended Values: The threshold limit value for occupational exposure to ultraviolet radiation incident upon skin or eye where irradiance values are known and exposure time is con trolled are as follows: 1. For the near ultraviolet spectral region (320 to 400 nm) total irradiance incident upon the unprotected skin or eye should not exceed 1 mw/cm2 for periods - greater than 10* seconds (approximately 16 minutes) and for exposure times less than 103 seconds should not exceed one J/cm2. 2. For the actinic ultraviolet spectral region (200 -- 315 nm), radiant exposure incident upon the unprotected skin or eye should not exceed the values given in Table 9 within an 8-hour period. 3. To determine the effective irradiance of a broadband source weighted against the peak of the spectral ef fectiveness curve (270 nm), the foliowing weighting formula should be used: "See User TIVs. 85l. l.______ x LAM025136 where: Eoy = effective irradiance relative to a monochromat ic source at 270 nm in W/cm2 (J/s/cm2) Ei = spectral irradiance in W/cm2/nm S* = relative spectral effectiveness (unitless) Ax = band width in nanometers 4. Permissible exposure time in seconds for exposure to actinic ultraviolet radiation incident upon the un protected skin or eye may be computed by dividing 0.003 J/cm2 by E^in W/cm2. The exposure time may also be determined using Table 10 which pro vides exposure times corresponding to effective irradiances in /AV/cm2. TABLE 9 Relative Spectral Effectiveness by Wavelength Wavelength (nm) 200 210 220 230 240 250 254 260 270 280 290 300 305 310 315 TLV (mJ/cm2)** 100 40 25 16 10 7.0 6.0 4.6 3.0 3.4 4.7 10 50 200 1000 Relative Spectral Effectiveness S,, 0.03 0.075 0.12 0.19 0.30 0.43 0.5 0.65 1.0 0.88 0.64 0.30 0.06 0.015 0.003 **lm J/cm2 10"'J/cm2 86 TABLE 10 Permissible Ultraviolet Exposures Duration of Exposure Per Day Effective Irradiance. E^^W/cm2)*** 8hrs......................................................... 0.1 4 hrs......................................................... 0.2 2 hrs......................................................... 0.4 1 hr.......................................................... 0.8 30 min...................................................... 1.7 15 min..................................................... 3.3 10 min...................................................... 5 5 min........................................................ 10 1 min........................................................ 50 30 sec...................................................... 100 10 sec...................................................... 300 1 sec...........................................................3,000 0.5 sec..................................................... 6,000 0.1 sec..................................................... 30,000 All the preceding TLVs for ultraviolet energy apply to sources which subtend an angle less than 80. Sources which subtend a greater angle need to be measured only over an angle of 80. tnW/cm1 -10"* W/art2 87 SC 16334 l. .... LAM025137 figure 8 -- Threshold Limit Values for Ultraviolet Radiation Conditioned (tanned) individuals can tolerate skin ex posure in excess of the TLV without erythema) effects. However, such conditioning may not protect persons against skin cancer. NOTICE OF INTENDED CHANGES (for 1977) These physical agents, with their corresponding val ues, comprise those for which either a limit has been proposed for the first time, or for which a change in the "Adopted" listing has been proposed. In both cases, the proposed limits should be considered trial limits that will remain in the listing for a period of at least one year. If after one year no evidence comes to light that questions the appropriateness of the values herein the values will be reconsidered for the "Adopted" list. 88 MICROWAVES These Threshold Limit Values refer to microwave en ergy in the frequency range of 300 MHz to 300 GHz and represent conditions under which it is believed that near ly all workers may be repeatedly exposed without ad verse effect. Under conditions of moderate to severe heat stress, the recommended values may need to be reduced.* Therefore, these values should be used as guides in the control of exposure to microwave energy and should not be regarded as a fine fine between safe and dangerous levels. Recommended Values: The Threshold Limit Value for occupational exposure to microwave energy, where power density or field in tensity is known and exposure time is controlled, is as follows: 1. For exposure to continuous wave (CW) sources, the power density level shall not exceed 10 milliwatts per square centimeter (mW/cm2) for continuous expo sure, and the total exposure time shall be limited to an 8-hour workday. This power density is approxi mately equivalent to a free-space electric field strength of 200 volts-per-meter rms (V/m) and a free-space magnetic field strength of 0.5 ampere-permeter rms (A/m). 2. Exposures to CW power density levels greater than 10 mW/cm2 are permissible up to a maximum of 25 mW/cm2 based upon an average energy density of 1 milliwatt-hour per square centimeter (mWh/cm2) averaged over any 0.1 hour period. For example, at 25 mW/cm2, the permissible exposure duration is approximately 2.4 minutes in any 0.1 hour period. 3. For repetitively pulsed microwave sources, the average field strength or power density is calculated by multiplying the peak-pulse value by the duty cycle. The duty cycle is equal to the pulse duration in sec- 'Mumford. W.W.. "Heat Stress Due to R. F. RacSaticn." Proceedings of IEEE. Vol. 57, No. 2. Feb. 1969, pp. 171-178. 89 SC 16335 LAM025138 <1 onds times the pulse repetition rate in Hertz. Expo sure during an 8-hour workday shall not exceed the following values which are averaged over any 0.1 hour period: Power Density Energy Density Mean Squared Electric Field Strength Mean Squared Magnetic Field Strength 10 mW/cm2 1 mWh/cm2 40,000 V2/m2 0.25 A2/m2 4. Exposure is not permissible in CW or repetitively pulsed fields with an average power density in excess of 25 mW/cm2 or approximate equivalent free-space field strengths of 300 V/m or 0.75 A/m. NOTICE OF INTENT TO ESTABLISH THRESHOLD LIMIT VALUES LIGHT AND NEAR-INFRARED RADIATION These Threshold Limit Values refer to visible and near-infrared radiation in the wavelength range of 400 nm to 1400 nm and represent conditions under which it is believed that nearly all workers may be exposed with out adverse effect. These values should be used as guides in the control of exposure to light and should not be regarded as a fine line between safe and dangerous levels. Recommended Values: The Threshold Limit Value for occupational exposure to broad-band light and near-infrared radiation for the eye apply to exposure in any eight-hour workday and require knowledge of the spectral radiance (L*) and total irradiance (E) of the source as measured at the posi tions) of the eye of the worker. Such detailed spectral data of a white light source is generally only required if the luminance of the source exceeds 1 cd cm"2. At lu minances less than this value the TLV would not be ex ceeded. The TLV's are: 1. To protect against retinal thermal injury, the spectral radiance of the lamp weighted against the function R 90 (Table 11) should not exceed: woo ,____ 2LxRAXS VT/at 400 (1) where Lx is in W cm-2 sr-1 and t is the viewing duration (or pulse duration if the lamp is pulsed) lim ited to 1 vs to 10 s, and a is the angular subtense of the source in radians. If the lamp is oblong, a refers to the longest dimension that can be viewed. For in stance, at a viewing distance r = 100 cm from a tubular lamp of length I = 50 cm, the viewing angle is: a = l/r =50/100 = 0.5 rad (2) 2. To protect against retinal injury from chronic blue- light exposure the integrated spectral radiance of the lamp weighted against the blue-light hazard function (Table 11) should not exceed: MOO ^ LxtB* AxsioOJcm^sr"1 (t =sios) (3a) J Lx Bx AX 10"2 Wcm"2 sr' (t > 10*s) (3b) For a source radiance L which exceeds 2 mW cm"2 sr"1 in the blue spectral region, the permissible ex posure duration t,,,, in seconds is simply: tw = 100 J cm "* sr-VL (blue) (4) The latter limits are greater than the maximum per missible exposure limits for 440 nm laser radiation (see Laser TLV) because a 2-3 mm pupil is assumed rather than a 7 mm pupil for the Laser TLV. 3. Infrared Radiation: To avoid possible delayed effects upon the lens of the eye (cataractogenesis), the infra red radiation (X > 770 nm) should be limited to 10 mWcrn-2. For an infrared heat lamp or any near-in frared source where a strong visual stimulus is ab sent, the near infrared (770-1400 nm) radiance as viewed by the eye should be limited to: T Ex Ax = 600/a (5) for extended duration viewing conditions. This limit is based upon a 7 mm pupil diameter. 91 SC 16336 __________ A. LAJW025139 I TABLE 11 AIRBORNE UPPER SONIC AND ULTRASONIC ACOUSTIC RADIATION SPECTRAL WEIGHTING FUNCTIONS FOR ASSESSING RETINAL HAZARDS FROM BROAD -- BAND OPTICAL SOURCES These threshold limit values refer to sound pressure levels that represent conditions under which it is be lieved that nearly all workers may be repeatedly exposed Blue-Light Burn Hazard without adverse effect. The values listed in Table 15 Wavelength Hazard Function Function should be used as guides in the control of noise expo (nm) B. R sure and, due to individual susceptibility, should not be 400 0.10 405 0.20 410 0.40 415 0.80 420 0.90 425 0.95 1.0 regarded as fine lines between safe and dangerous 2.0 levels. The levels for the third octave bands centered 4.0 below 20 kHz are below those which cause subjective 8.0 effects. Those levels for 1/3 octaves above 20 kHz are 9.0 for prevention of possible hearing losses from subhar 9.5 monics of these frequencies. 430 0.98 9.8 435 1.0 10 440 1.0 10 TABLE 12 Permissible Ultrasound Exposure Levels 445 450 455 460 465 470 475 480 485 490 495 500-600 0.97 0.94 0.90 0.80 0.70 0.62 0.55 0.45 0.40 0.22 0.16 jQt<4S0-X)W>] 9.7 Mid-Frequency of 9.4 Third-Octave Band One-Third Octave -- Band Level 9.0 kHz in dB reference 0.0002 dynes/cm2 8.0 7.0 6.2 5.5 10 12.5 16 4.5 4.0 2.2 20 25 31.5 1.6 1.0 40 50 80 80 80 105 110 115 115 115 600-700 0.001 1.0 700-1060 0.001 1QH700-AVJI5) 1060-1400 0.001 0.2 i * 1t' 92 SC 16337 93 T'T^T `\ I______ Jl LAM025140 . NOTICE OF INTENT TO STUDY These agents comprise those which the Physical Agents Committee of ACGIH proposes to study during this year to determine the feasibility of establishing pro posed TLVs in 1977 Comments and suggestions, ac companied by substantitive evidence, are solicited. 1. Radiofrequency Radiation. Specifically, that portion of the spectrum from 10 MHz to 100 MHz. 2. Microwave Radiation. Specifically from 100 GHz to 300 GHz. 3. Magnetic Helds. Both pulsed and continuous. 4. Laser Radiation. Specifically ultraviolet radiation for pulsed exposures, and repetitively pulsed light and infrared-A laser ex posures. 5. Ultrasonic Energy. Specifically, acoustic energy at frequencies above 10 kHz. 6. Vibration. Segmental and whole-body. The American Conference of Governmental Industrial Hy gienists was organized in 1938 by a group of govern mental industrial hygienists who desired a medium for the free exchange of ideas, experiences and the promo tion of standards and techniques in industrial health. The Conference is not an official Government Agency. it is an organization devoted to the development of ad ministrative and technical aspects of worker health pro tection. The association has contributed substantially to the development and improvement of official industrial health services to industry and labor. The committees on industrial Ventilation and Threshold Limit Values are re cognized throughout the world for their expertise and contributions to industrial hygiene. Membership is limited to professional personnel in gov ernmental agencies or educational institutions engaged in occupational safety and health programs. 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