Document gD4RzBvEJ5Rdwyoqoo6X2oj6e

TLVs Threshold Limit Values for Chemical Substances and Physical Agents in the Workroom Environment with Intended Changes for 1972 210 Copyright 1972 by American Conference of Governmental Industrial Hygienists. The American Conference of Govern mental Industrial Hygienists will welcome requests for permission to republish or re print 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......................................................... 7U 50-200 ..................................................... 65^ Quantities over 200, prices upon request Documentation of the Threshold Limit Values for Substances in Workroom Air. A separate companion piece to the Airborne 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 contains 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 Documentation 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 Chairman, TLV Committee. 0 v ry---- TLVs Threshold Limit Values for Substance in Workroom Air Adopted by ACGIH for 1972 1972 TLV AIRBORNE CONTAMINANTS COMMITTEE Hector P. Blcjer, M.D., D.I.H. Paul E. Caplan, P.E., M.P.H. William Durham, Ph.D. Hervey B. Elkins, Ph.D. W.G. Frederick, Sc.D. Bernard Grabois, P.E. Paul Gross, M.D. John W. Knauber, M.P.H. Harold N. MacFarland, Ph.D. Frederick T. McDermott, P.E. E. Mastromatteo, M.D. Col. Walter W. Melvin, Jr., M.D. Ralph G. Smith, Ph.D. Mitchell R. Zavon, M.D. Herbert E. Stokinger, Ph.D., Chairman William D. Wagner, Recording Secretary LIAISON MEMBERS David A. Padden, Labor Union James F. Morgan, Industry Vernon K. Rowe, Industry Theodore R. Torkelson, Sc.D., Alternate 02700 1 PREFACE AIRBORNE CONTAMINANTS Threshold limit values refer to airborne concentrations of substances and represent conditions under which it is believed that nearly all workers may be repeatedly exposed day after day without adverse effect. Be cause of wide variation in individual suscep tibility, however, a small percentage of workers may experience discomfort from some substances at concentrations at or below the threshold limit, a smaller per centage may be affected more seriously by aggravation of a pre-existing condition or by development of an occupational illness. Simple tests are now available (J. Occup. Med. 9: 537, 1967; Ann. N.Y. Acad. Sci., 151, Art. 2: 968, 1968) that may be used to detect those individuals hypersusceptible to a variety of industrial chemicals (respira tory irritants, hemolytic chemicals, organic isocyanates, carbon disulfide). These tests may be used to screen out by appropriate job placement the hyperreactive worker and thus in effect improve this "coverage" of the TLVs. Threshold limit values refer to timeweighted concentrations for a 7 or 8-hour workday and 40-hour workweek. They should be used as guides in the control of health hazards and should not be used as fine lines between safe and dangerous con centrations. (Exceptions are the substances listed in Appendices B and F and those substances designated with a "C" or Ceiling value, Appendix D) Time-weighted averages permit excur sions above the limit provided they are 1 ' o V '1 O compensated by equivalent excursions below the limit, during the workday. In some in stances it may be permissible to calculate the average concentration for a workweek rather than for a workday. The degree of permissible excursion is related to the magnitude of the threshold limit value of a particular substance as given in Appendix D. The relationship between threshold limit and permissible excursion is a rule of thumb and in certain cases may not apply. The amount by which threshold limits may be exceeded for short periods without injury to health depends upon a number of factors such as the nature of the contaminant, whether very high concentrations -- even for short periods -- produce acute poison ing, whether the effects are cumulative, the frequency with which high concentrations occur, and the duration of such periods. All factors must be taken into consideration in arriving at decision as to whether a hazardous condition exists. Threshold limits are based on the best available information from industrial ex perience, from experimental human and animal studies, and, when possible, from a 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 guiding 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 substance; consequently, the n 4- precision of the estimated TLV is also sub ject to variation and the latest Documenta tion 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 binding than those based on physical impairment. There is increasing evidence that physical irritation may initiate, promote or accelerate physical impairment through interaction 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 concentrations, the best practice is to maintain concentrations of all atmospheric contaminants as low as is practical. 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 in tended for use, or for modification for use, (1) as a relative index of hazard or toxicity, (2) in the evaluation or air pollution nui sances, (3) in estimating the toxic potential of continuous, uninterrupted exposures, (4) as proof or disproof of an existing disease or physical condition, 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 con centration provides the most satisfactory, .0 0 * (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 procedures necessary for their removal. A threshold limit of 10mg/m3, or 30 mppcf, of total dust <1% quartz is recom mended for substances in these categories and for which no specific threshold limits have been assigned. This limit, for a normal workday, does not apply to brief exposures at higher concentrations. 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 particu lates are given in Appendix E. Simple Asphyxiants--"Inert" Oases or Vapors. A number of gases and vapors, when present in high concentrations in air, act primarily as simple asphyxiants without other significant physiologic effects. A TLV may not be recommended for each simple asphyxiant because the limiting factor is the available oxygen. The minimal oxygen con tent should be 18 percent by volume under normal atmospheric pressure (equivalent to a partial pressure, p02 of 135 mm Hg). Atmospheres deficient in O2 do not provide adequate warning and most simple asphyx iants are odorless. Several simple asphyx iants present an explosion hazard. Account should be taken of this factor in limiting the concentration of the asphyxiant. Specific examples are listed in Appendix F. Physical Factors. It is recognized that such physical factors as heat, ultraviolet and ionizing radiation, humidity, abnormal 21027010 pressure (altitude) and the like may place added stress on the body so that the effects from exposure 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 moderate deviations from normal environments, the safety factors of most substances are not of such a magnitude as to take care of gross deviations. For ex ample, continuous work at temperatures above 90 F or overtime extending the work week more than 25%, might be considered gross deviations. In such instances judgment must be exercised in the proper adjustments of the threshold limit values. "Notice of Intent." At the beginning of each year, proposed actions of the Com mittee for the forthcoming year are issued in the form of a "Notice of Intended Changes." This Notice provides not only an oppor tunity for comment, but solicits suggestions of substances to be added to the list. The suggestions should be accompanied by sub stantiating 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 are now official federal standards for industrial air. Reprint Permission. This publication may be reprinted provided that v'ritten permission is obtained from the SecretaryTreasurer of the Conference and that it be published in its entirety. .7 O- hrw SS/ hg * Substance ppm") Trifluoromonobromo- methane...................... 1,000 Trimethyl benzene......... 25 2,4,6-Trinitrophenol, see Picric acid................... 2, 4, 6 -- Trinitrophenyl- methylnitramine, see Tetryl......................... Trinitrotoluene -- Skin.. -- Triorthocresyl phosphate................... ---- Triphenyl phosphate.... Tungsten & compounds, as W Soluble..................... Insoluble................. Turpentine..................... -- -- 100 Uranium (natural) sol uble & insoluble com- pounds, as U.............. ~~ Vanadium (V2O5), as V Dust............................ Fume........................... Vinyl acetate.................. Vinyl benzene, see Sty- rene.............. ............... : Vinyl bromide................ Vinyl chloride................. -- -- 10 -- 250 200 Vinylcyanide, see Acrylonitrile............... Vinyl toluene................. --- ' 100 Warfarin......................... ' Wood dust (nonallergenic)........... Xylene (xylol)................ -- 100 36) mg/M 6,100 120 1.5 0.1 3 1 5 560 0.2 0.5 0.05 30 ---- 1,100 770 -- 480 0.1 5 435 Capital letters refer to Appendices. *1972 Addition. Si&rroco Substance 3^) ppma> mg/M Xylidine -- Skin............. Yttrium.......................... Zinc chloride fume....... Zinc oxide fume............. Zirconium compounds (as Zr)......................... 5 -- -- -- 25 1 1 5 a) Parts of vapor or gas per million parts of contaminated air by volume at 25 C and 760 mm. Hg. pressure. b) Approximate milligrams of substance per cubic meter of air. d) An atmospheric concentration of not more than 0.02 ppm, or personal protec tion may be necessary to avoid headache. e) < 5-7 pun 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 concentra tions of radioisotopes in air, see U.S. De partment of Commerce, National Bureau of Standards Handbook 69, "Maximum Per missible Body Burdens and Maximum Per missible Concentrations of Radionuclides in Air and in Water for Occupational Expo sure," June 5, 1969. Also, see U.S. Depart ment of Commerce National Bureau of Standards, Handbook 59, "Permissible Dose from External Sources of Ionizing Radia tion," September 24, 1954, and addendum of April 15, 1958. A report, Basic Radiation Protection Criteria, published by the Na- O O W T V3.E Goodrich / M- uwJfL. - tu^st 1*4 jJ 5Jj~jJLj $&-ulk H `*hle -u~<- 7 / 'y?'* J2- __________ =><__________________________ >k?___________________________________________________________________________________ -- -1 h O TJ* 5- PRINTED IN U.S.A