American Journal of Industrial Medicine 17:727-753 (1990) But They Are Not Thresholds: A Critical Analysis of the Documentation of Threshold Limit Values S.A. Roach, DSc, PhD, and S.M. Rappaport, PhD Threshold Limit Values (TLVs) represent conditions under which the TLV Committee of the American Conference of Governmental Industrial Hygienists (ACGIH) believes that nearly all workers may be repeatedly exposed without adverse effect. A detailed research was made of the references in the 1976 Documentation to data on “industrial experience” and “experimental human studies. ” The references, sorted for those in- cluding both the incidence of adverse effects and the corresponding exposure, yielded 158 paired sets of data. Upon analysis it was found that, where the exposure was at or below the TLV, only a minority of studies showed no adverse effects (1 1 instances) and the remainder indicated that up to 100% of those exposed had been affected (8 instances of 100%). Although, the TLVs were poorly correlated with the incidence of adverse effects, a surprisingly strong correlation was found between the TLVs and the exposures ,reported in the corresponding studies cited in the Documentation. Upon repeating the search of references to human experience, at or below the TLVs, listed in the more recent, 1986 edition of the Documentation, a very similar picture has emerged from the 72 sets of clear data which were found. Again, only a minority of studies showed no adverse effects and TLVs were poorly correlated with the incidence of adverse effect and well correlated with the measured exposure. Finally, a careful analysis revealed that authors’ conclusions in the references (cited in the 1976 Documentation) regarding exposure-response relationships at or below the TLVs were generally found to be at odds with the conclusions of the TLV Committee. These findings suggest that those TLVs which are justified on the basis of “industrial experience” are not based purely upon health considerations. Rather, those TLVs appear to reflect the levels of exposure which were perceived at the time to be achievable in industry. Thus, ACGIH TLVs may represent guides of levels which have been achieved, but they are certainly not thresh- olds. Key words: TLV, industrial experience, air contaminants, workplace exposures, irritation, health impairment, narcosis INTRODUCTION The list of Threshold Limit Values (TLVs) of the American Conference of Governmental Industrial Hygienists (ACGIH) has had a profound influence upon the Northern California Occupational Health Center, School of Public Health, University of California, Berkeley. Address reprint requests to Dr. S.M. Rappaport, Northern California Occupational Health Center, School of Public Health, University of California, Berkeley, CA 94720. Accepted for publication October 22, 1989. 0 1990 Wiley-Liss, Inc. 728 Roach and Rappaport state of occupational hygiene in the U.S. and, indeed, throughout the world. Al- though intended as unofficial guides of acceptable exposure to chemical and physical agents in the workplace, these limits are widely applied as official limits by many states and countries. In point of fact, in the U. S . , the Occupational Safety and Health Administration (OSHA) has twice adopted essentially the entire list of TLVs for Chemical Substances as enforceable limits: first the 1968 list under a one-time pro- vision made for incorporating existing federal and national consensus standards (Sect. 6(a), OSH Act) [OSH Act, 19701, and recently the 1987/88 list in an unprecedented action [OSHA, 19891. ACGlH TLVs formed the basis of the West German list of maximum workplace concentrations (MAKs) [Henschler, 19841, the British list of occupational exposure standards (OESs) [Health and Safety Executive, 19891, the Japanese list of maximum permissible exposure limits (PELS) [Toyama, 19851, the Swedish list of hygienic limit values (HLVs) [Nordberg et al., 19881, and many other lists. The ACGIH defines TLVs for chemical substances as follows [ACGIH, 19881: “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.” This statement clearly implies that the TLVs are based primarily upon health considerations since ‘‘nearly all” workers exposed at the level of the TLV over a working lifetime would be protected. The current Chair of the Chemical Substances TLV Committee confirmed this when he stated that [Mastromatteo, 19881, “TLVs are health-based recommendations derived from assessment of the available published scientific information from studies in exposed humans and from studies in experimental animals. For each TLV, there has to be a published documentation supporting the committee recommendation. ” Given these statements, it is not surprising that the various practitioners of occupational health generally believe that the TLVs afford substantial protection to the working population. Yet recently, both the process by which the TLVs have been established [Castleman and Ziem, 19881 and the data supporting the limits [Hen- schler, 1984; Zielhuis, 19881 have been called into question. Furthermore, each year, some of the values are changed, and in the majority of instances they are reduced, sometimes to one-half or one-tenth of their previous value. A past Chairman and TLV Committee member, in a robust defense of TLVs, remarked recently that “. . . throughout all the more than 40 years existence of threshold limit values, there has been no instance of serious health effects, provided exposures were kept at or below the TLVs.” [Stokinger, 19881 Why then, it may be asked, have TLVs for such chemicals as benzene, vinyl chloride, and methyl chloride come down from early values of 100 ppm, 500 ppm and 20,000 ppm [Cook 19451 to current levels of 10 ppm, 5 ppm and 1000 ppm [ACGIH, 19881, respectively? Since most values are eventually reduced, one cannot help but wonder if the TLVs, indeed, protected nearly all workers during the transition period. Resolution of this apparent contradiction in the meaning of TLVs can perhaps be resolved by examining more closely the key phrase, “nearly all workers.” Here again the current Chairman of the Committee offered the following clarification [Mastromatteo, 19881: “TLVs are based on the belief in a threshold or thresholds below which no adverse health effects would occur in workers . . . although . . . some workers with individual susceptibility may not be protected by the recommended TLVs.” This notion that the TLVs protect all workers save, perhaps, a sensitive Analysis of Threshold Limit Values 729 subpopulation of persons especially susceptible on grounds of abnormal heredity, sensitization, disease, habits, sex, or reproductive status [de Silva, 19861, is reaf- firmed annually by the ACGIH as follows [ACGIH, 19881: Because of wide variation in individual susceptibility, however, a small percentage of workers may experience discomfort from some substances at concentrations at or below the threshold limit: a smaller percentage may be affected more seriously by aggravation of a pre-existing condition or by development of an occupational illness. This statement indicates that a “small percentage” would experience discomfort, as perhaps would occur with a respiratory irritant, and that ‘‘a smaller percentage” might contract a chronic disease at or below the level of the TLV. To find further enlightenment as to what is meant by “small percentage” and “smaller percentage,” it is necessary to analyze the documentation supRorting the TLVs in detail and the references given therein. A separate companion piece to the TLV booklet is issued by the ACGIH under the title, Documentation of the Threshold Limit Values and Bio- logical Exposure Indices [ACGIH, 19861, In the TLV booklet the reader is urged to consult this Documentation when TLVs are being used [ACGIH, 19881. When evaluating the evidence compiled in the Documentation it becomes clear that the TLV Committee has traditionally placed greatest importance upon studies involving human experience. This was stated unequivocally by a former Chairman of the Committee, H. Stokinger, about 20 years ago [see Stokinger, 19841 and supported more recently by Smyth [1984], who indicated that evidence based upon animal experiments must only serve until it can be replaced with documented human expe- rience. Some 10 years ago one of us studied the references to human experience listed under each substance in the 1976 Documentation of the TLVs f o r Chemical Sub- stances [Roach, 19821. We have recently analyzed the 1986 Docurnentation [ACGIH, 19861 to investigate whether the situation has changed since 1976, and in what follows we will summarize our findings from both investigations. 1976 DOCUMENTATION In the 1976 list there were TLVs for 488 chemicals of which 225 TLVs were based at least in part on human experience. Copies of all the original published references to human experience were sought. The major references were the ones most easily located and contained the most useful information. Older and more abstruse references were progressively more difficult to obtain. The search was dis- continued when the arbitrary target of 80% of the published references to human experience had been acquired. References where the atmospheric exposure of the persons was doubtful or was not measured were put to one side. References in which there were doubts about the incidence of the effect the TLV was designed to prevent were also put aside as were those where the number of exposed persons was unclear. This left references to 70 substances which included data for 158 different groups of employees varying in size from one to 1,802 employees (median 10-1 1 employees). Information derived from these references is comprehensively compiled in Appendices A-C according to the measured exposure and the nature of the effect which served as the basis for the TLV 730 Roach and Rappaport (impairment of health, irritation, or narcosis). The key references from which the data were extracted are also indicated. The pertinent results are summarized in Table I where the incidence of adverse effects is given for persons exposed at or below the TLV. Some studies did show every employee to be free of adverse effects when exposed at or below the TLV (1 I instances). However, scrutiny of Table I shows that most studies demonstrated an incidence of adverse effects which was substantially above zero at the TLV and which was even 100% in some cases (8 instances). This was particularly true regarding exposure to irritants, where 93 of 174 individuafs exposed at or below the TLV experienced effects. At exposure levels above the TLVs, the incidence of adverse effects tended to be higher when the basis for the TLV was irritation or narcosis than when the basis was impairment of health. When all studies in Table I are combined, 17% of employees exposed to a concentration at or below the level of the 1976 TLV were adversely affected. When exposure is expressed as a multiple of the TLV and related to the inci- dence of adverse effects, as in Figure 1 , it is apparent that there was no correlation between the two variables (r2 = 0.005; p = 0.39). On the other hand, the correlation between the TLV adopted for a substance and the concentrations reported in the corresponding studies listed in the Documentation was highly significant (Fig. 2; r2 = 0.26; p 1.00 25 Carbon disulfide 16 16 1.oo 100 Carbon disulfide 100 39 < 0.53 39 Carbon disulfide 100 53 0.73" 53 Carbon tetrachloride 6 0 1 .oo 0 Chlorine dioxide 12 7 < 1.00 58 Chlorodiphenyl-42% cl 14 7 0.10 50 Ethylene oxide 37 0 0. Ha 0 Fluoride 189 48 0.66" 25 Lead 143 21 0.93 15 Magnesium oxide fume 4 I 0.58 25 Magnesium oxide fume 4 2 0.41 50 Mercury 3 0 0.80 0 Mercury 9 1 0.40 11 Mica 109 1 0.10 92 Mica 61 20 0.50 33 2-Nitropropane 2 0 0.80" 0 Sulfuric acid 15 0 0.43" 0 Tetryl 1 I82 50 1 .oo 4 Toluene 3 1 I .oo 33 Toluene 2 1 0.50 50 Toulene 2,4 diisocyanate 12 0 1.OO" 0 Total: 2524 369 14.6 Irritation Ally1 alcohol 6 2 0.39 33 Butyl alcohol 10 10 0.50 100 Butyl alcohol 10 10 1 .oo 100 Cyanogen 5 0 0.80 0 Ethyl acetate 10 10 1 .oo 100 Ethyl ether 10 10 0.75 100 Propylene glycol monomethyl ether 1 0 0.47 0 Propylene glycol monomethyl ether 6 4 0.95 67 Selenium 62 9 0.1Y 15 Styrene monomer 6 3 0.99 50 Styrene monomer 3 0 0.51 0 Vanadium pentoxide 8 8 0.72 100 Vanadium pentoxide 24 20 0.40" 83 Vanadium pentoxide 5 5 0.40 100 Vanadium pentoxide 2 2 0.20 100 Vinyl chloride 6 0 0.30 0 Total: 174 93 53.4 Narcosis Perchloroethvlene 8 2 0.96 25 "Exposure assigned at midpoint of range. 732 Roach and Rappaport + ;~ + * loo0 t I i >, t W 5a 0 P X (I1!; 10 1 +*+++ 0.1 ++ + + : : ++ + +++ + + * $+ * ++ +$ +++++++ + + + *+ ++ *+ + + +u+ * + + ++ 0.0 1 0 20 40 60 80 100 % Adversely Affected Fig. I . Exposure expressed as a multiple of the TLV vs. the percent of individuals adversely affected. From refcrences to human experience given in the 1976 Docurnentarion of TLVs. (Data givcn in Ap- pendices A-C.) Exposure Fig. 2. TLV vs. the exposures reported in all studies for particular air contaminants. From references to human experience given in 1976 Documentation of TLVs. (Data given in Appendices A-C.) (13 instances) to 100% ( 3 instances) and, as shown in Table 11, it appeared that, overall, 14% of employees exposed at or below the 1986 TLV were adversely af- fected. Unlike the data gleaned from the 1976 Docurnentation, there was a weak but statistically significant linear correlation between exposure, expressed as a multiple of the TLV, and the percent of individuals affected (Fig. 3; r2=0.17; p=<0.001). Analysis of Threshold Limit Values 733 100 t + + 101 + + + ++ + + ++ > ++: * 2 +$ t + + + + 2a 11: ++ + ++ a 0 P + *+ W f 0 20 40 60 80 100 % Adversely Affected Fig. 3. Exposure expressed as a multiple of the TLV vs. the percent of individuals adversely affected. From references to human experience given in the 1986 Documentation of TLVs. (Data given in Ap- pendices D, E.) However, as shown in Figure 4, the correlation between the TLV adopted and the concentrations reported in the studies of particular contaminants was very strong (?=0.61; p 0.002 mgim 0.002 mg/m’ > l 931372 Lungs Cadmium cpds. 0.02-0.24 mglm3 0.05 mg/m3 0.4-4.8 12119 Kidneyllungs d ~ s t ’ ~ . ’ ~ 0.13 mglm’ 0.05 mglm3 2.5 4121 Kidneyllungs 0.07 m g h 3 0.05 mgim-’ I .4 14122 Kidne yllungs (continued) Analysis of Threshold Limit Values 745 APPENDIX A. Documentation of 1976 TLVs Based Upon References to Human Experience: Hazard-“Impairment of Health” (continued) Air concentration Individuals Organ Substance Exposure TLV (ExposureiTLV) affected affected Carbon 20 PPm 1.o 16/16 CNS di~ulfide’~.’’ 3-26 ppm 0.15-1.3 53/100 CNS < 10 ppm < 0.5 391 100 CNS Carbon tetra- 85 ppm 8.5 4/4 Livedkidney 45-97 ppm 4.5 -9.7 15/17 Livedkidne y 49 PPm 4.9 316 Livedkidney 10 PPm 1.o 016 Chlordane’ 14 mg/m’ 28.0 0/22 - Chlorine 0.2-ppm 0-20 25/69 Lungs < 0.1 ppm < 1.0 7/12 Lungs Chlorodiphenyl- 0.1 mg/m3 0.1 7114 Skidliver 42% chlorine** Cobalt*’,24 0.1-1.7 mg/m’ 0 . 1 mgim’ 1 .O-17.0 1,352/1,802 Lungs 0.1-0.2 mgim’ 0. I mgim’ 1-2 3/1,500 Lungs Cotton 2.6 mg/m3 0.2 mg/m3 13.0 142/217 Lungs d ~ s t * ~ - * ~ 0.6 mg/m3 0.2 mg/m3 3.0 203/793 Lungs 0.3 mg/m3 0.2 nigim’ 1.5 1601566 Lungs Ethylene 300-500 ppm 1 PPm 300-500 616 Liver/CNS chlorohydrin” Ethylene 5-10 ppm 50 PPm 0.1-0.2 0.37 oxide’” Fl~oride’”~~’ 2.8 1 mg/m3 2.5 mg/m3 1.1 17/74 Bones 0.14-3.13 mg/m3 2.5 mg/m’ 0.06-1.25 481 189 Bones Fl~orine’~ 1.2 ppm 1 PP” I .2 0.61 He~ane’~ 500 ppm 100 ppm 5.0 o/ 10 - Hydrogen < 0.2 ppm 0.05 ppm < 4.0 5/25 Lungs ~elenide’~ Lead” 5.0 mgim’ 0.15 mg/m3 33 27/28 Blood/kidne y 2.0 mgim’ 0.15 mgim’ 13.3 24/3 1 Bloodikidney I .O mg/m’ 0.15 mg/m3 6.7 56/69 Blood/kidney 0.14 mg/m3 0.15 mg/m3 0.93 21/143 Bloodikidney 0.5 mg/m3 0.15 mg/m3 3.3 15/32 Bloodlkidney Magnesium 5.8 mg/rn3 10 mgim’ 0.6 1/4 Lungs oxide 4.1 mg/m3 10 mg/m3 0.4 214 Lungs fume36 Mercury 0.40 mg/m3 0.05 mg/m3 8.0 115 CNS (In~rganic)~’ 0.27 mg/m3 0.05 mgim’ 5.4 6/26 CNS 0. I 9 mgirn’ 0.05 mg/m3 3.8 8/11 CNS 0.13 mg/m3 0.05 mg/m3 2.6 9/32 CNS 0.08 mg/m’ 0.05 mg/m3 1.6 21 17 CNS 0.04 mg/m3 0.05 mgim’ 0.8 013 CNS 0.02 mgim’ 0.05 mgim’ 0.4 119 CNS Methylene 985 pprn 200 ppm 4.9 213 CNSiblood ~hloride’~ 690 ppm 200 pprn 3.5 113 CNS/blood 515 ppm 200 ppm 2.6 0.8 213 pprn 200 ppm 1.1 o/ 1 Mica39”.40 80 mppcf 20 mppcf 4.0 3/47 Lungs 42 mppcf 20 mppcf 2.1 1/12 Lungs 10 mppcf 20 mppcf 0.5 2016 1 Lungs 2 mppcf 20 mppcf 0.1 1/109 Lungs (continued) 746 Roach and Rappaport APPENDIX A. Documentation of 1976 TLVs Based Upon References to Human Experience: Hazard-"Imuairment of Health" (continued) ~ ~~~~ Air concentration Individuals Organ Substance Exposure TLV (Exposure1TLV) affected affected Nitrobenzene3 6 ppm 1 PPm 6.0 0.39 p-Nitrochloro- 20 mg1m' I mg/m3 20 0139 benzene3 Nitrogen 196 ppm 5 PPm 39 414 Lungs dioxide4' 80 ppm 5 PPm 16 111 Lungs 2-Nitro~ropane~~ 20-45 ppm 25 PPm 0.8-1.8 515 CNS 10-30 ppm 25 PPm 0.4-1.2 012 Phosphine4* 3-35 ppin 0.3 ppm 10-120 35167 Lungs Picric acid4' 0.009-0.194 mglm3 0.1 mg/m3 0.09-1.9 7/71 Skin Platinum 0.007 mglm' 0.002 m g i d 3.5 5219 1 Lungs soluble sa~ts~~,~' Silicon I00 mppcf 30 mppcf 3.3 19153 Lungs carbide4' Sulfuric 3-16.6 mg/m3 I mgim' 3-17 57163 Lungdteeth aCid48.49 < 0.8-2.5 mgim' I mg/m3 0.8-2.5 9/15 Lungslteeth 0.35-0.5 mg1m3 I mg/m3 0.35-0.5 0115 - Tetrabromo- < 14 ppm 1 PPm < 14 616 Liver cthanc50 1 , I ,2,2-Tetra- 53 ppm 5 PPm 10.6 54186 CNS chloroethane5' 43 ppm 5 PPm 8.6 391107 CNS 14 PPm , 5 PP'n 2.8 14152 CNS TetryI5' 1.5 mglm 1.5 mgim' 1 .o 501 1,182 Skin Toluenes3 800 ppm 100 ppm 8.0 313 BloodiCNS 600 ppm I00 ppm 6.0 313 BloodiCNS 400 ppm I00 ppm 4.0 313 BloodKNS 300 ppm 100 ppm 3.0 313 BloodiCNS 200 ppm 100 ppm 2.0 313 BloodiCNS 100 ppm 100 pprn 1 .0 113 BloodiCNS 50 PPm 100 ppm 0.5 112 Blood/CNS Toluene-2,4- 0.05 ppm 0.02 ppm 2.5 191260 Lungs diisocyanate 0.03-0.07 ppm 0.02 ppm 1.5-3.5 12112 Lungs (TDI)54.55 0.01-0.03 ppin 0.02 ppm 0.5-1.5 0.12 - 'Pozzani UC, Carpenter CP, Palm PE, Weil CS, Nair JH (1959): Mammalian toxicity of acetonitrile. 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Science 176:295 -296. 39Dreessen WC, Dallavalle JM, Edwards TI, Sayers RR, Eason HF, Trice MF (1940): "Pneumoconiosis Among Mica and Pegmatite Workers." Publ. Health Bull. No. 250, U.S. Publ. Health Serv. Washington DC: Government Printing Office. 4"Heimann H, Moskowitz S , Iyer CRH, Gupta MN, Mankiker NS (1953): Note on mica dust inhalation. Arch Ind Hyg Occup Med 8:531-532. 748 Roach and Rappaport 4iAdley FE (1946): Exposures to oxides of nitrogen accompanying shrinking operations. J Ind Hyg Toxicol 28:17-20. 42JonesAT, Jones RC, Longley EO (1964): Environmental and clinical aspects of bulk wheat fumigation with aluminum phosphide. Am Ind Hyg Assoc J 25:376-379. 4’Sunderman FW, Weidman FD, Batson OV (1945): Studies of the effects of ammonium picrate on man and certain experimental animals. J Ind Hyg Toxicol 27:241-248. 44HunterD, Milton R, Perry KMA (1945): Asthma caused by the complex salts of platinum. 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Arch Ind Hyg Occup Med 5:10-20. %on Oettingen WF, Neal PA, Donahue DD, Svirbely JL, Baerstein HD, Monaco AR, Valaer PJ, Mitchell JL (1942): “The Toxicity and Potential Dangers of Toluene, With Special Reference to Its Maximal Permissible Concentration.” Publ. Health Bull. 279. Washington: Government Printing Office. ”Hama GM (1957): Symptoms in workers exposed to isocyanates. Arch Ind Health 16:232-233. “Walworth HT, Virchow WE (1959): Industrial hygiene experiences with toluene diisocyanate. Am Ind Hyg ASSOCJ 20:205-210. APPENDIX B. Documentation of 1976 TLVs Based Upon References to Human Experience: Hazard-“Irritation” Air concentration (Exposure1 Individuals Organ Substance Exposure TLV TLV) aSSected affected Ally1 alcohol’ 25 PPm 2 PPm 12.5 515 Eyeslnose 12 5 ppm 2 PPm 6.3 417 Eyeslnose 6 25 ppm 2 PPm 3.1 316 Eyeslnose 0 78 ppm 2 PPm 0.4 216 Eyeslnose 2-Butoxy 195 ppm 50 PPm 3.9 313 Eyeslblood ethanol2 113 ppm 50 PPm 2.3 616 Eyeslblood n-Butyl acetate7 300 ppm 150 ppm 2.0 10110 EyesIURT 200 ppm 150 pprn 1.3 10110 EyesIURT Butyl alcohol 50 PPm 50 PPm 1.0 10110 EyesIURT (n-b~tanol)~ 25 PPm SO ppm 0.5 10110 EyeslURT a-Chloroaceto- 213 ppin 0 05 ppm 4,260 214 Eyes phenone4 119 ppm 0 05 pprn 2,380 214 Eyes 93 PPm 0 05 ppm 1,860 214 Eyes Chlorobenzilidene 0 2 pprn 0 05 ppm 4.0 414 Eyeslskin maIonitriIe’ Cydnogen6 16 PPm 10 PPm 1.6 717 EyeslURT 16 PPm 10 PPm I .6 517 EyeslURT 8 PPm 10 PPm 0.8 015 - Cyclohexanol’ 100 ppm 50 PPm 2.0 10110 EyeslURT Ethyl acetate7 400 ppm 400 ppm 1.o 10110 Eyes Ethyl ether’ 300 PPm 400 ppin 0.75 10/10 URT (continued) Analysis of Threshold Limit Values 749 APPENDIX B. Documentation of 1976 TLVs Based Upon References to Human Experience: Hazard-''Irritation'' (continued) Air concentration (Exposure1 Individuals Organ Substance Exposure TLV TLV) affected affected Hydrogen 50-80 ppm 10 PPm 5-8 88/125 Eyes sulfide7.' 18-28 ppm 10 PPm 1.8-2.8 25/78 Eyes Iodine' I.63 ppm 0.1 ppm 16.3 414 EyeslURT 0.57 ppm 0.1 ppm 5.7 014 - Isoamyl alcohol' 200 ppm 100 ppm 2.0 10110 EyeslURT Isophorone l o 25 PPm 5 PPm 5.0 8/12 EyeslURT 10 PPm 5 PPm 2.0 5/12 EyesIURT Mesityl oxide" 50 PPm 25 PP* 2.0 6/12 EyeslURT Methyl-2-cyano- 20 PPm 2 PPm 10 14/14 EyesIURT acrylate' ' Osmium 0.1-0.6 mglm3 0.002 mgim' 50-300 717 EyesIURT tetroxide' Ozone",'4 2 PPm 0.1 ppm 20.0 111 Lungs 0.8-1.7 ppm 0.1 ppm 8-17 11114 Lungs Propylene glycol 95 PPm 100 ppm 0.95 416 URT monomethyl 47 PPm 100 ppm 0.47 011 - ether" ~e~enium'~ 0.007-0.05 0.2 mg/m3 0.035-0.25 9/62 EyesiURT mg/m3 Stoddard 984-1,054 pprn 100 ppm 9.8-10.5 19/30 Eyes so~vent".'' 497-528 ppm 100 ppm 5.0-5.3 18/30 Eyes 270 ppm 100 ppm 2.7 9/13 Eyes 164-200 ppm 100 ppm 1 6-2.0 1/30 Eyes 160 ppm 100 ppm 1.6 4/8 Eyes Styrene 376 ppm 100 ppm 3.8 4/5 EyesICNC monomer19 216 ppm 100 ppm 2.2 1/3 EyesiCNC 117 ppm 100 ppm 1.2 0/ 1 - 99 PPm 100 ppm 1 .0 3/6 EyesICNC 51 PPm 100 ppm 0.5 0/3 - Vanadium I rngim' 0.5 mgim' 2.0 2/2 URT pentoxide 0.36 mg/m3 0.5 nig/m3 0.7 818 URT dUst20,21 0.1-0.3 mgim' 0.5 mg/m3 0.20-0.6 20124 URT 0.20 mg/m' 0.5 mg/m3 0.4 515 URT 0.1 rngim3 0.5 mg/m' 0.2 212 URT Vinyl chloridezz 460-490 ppm 200 ppm 2.3-2.5 2/11 Eyes 260 ppm 200 ppm 1.3 014 - 60 PPm 200 ppm 0.3 016 - 'Dunlap MK, Kodama JK, Wellington MD, Anderson MD, Hine CH (1958): The toxicity of ally1 al- cohol. AMA Arch Ind Health 18:303-3 l l . 'Carpenter CP, Pozzani UC, Weil CS, Nair JH, Keck GA, Smyth HF (1956): The toxicity of butyl cellosolve solvent. AMA Arch Ind Health 14:114-131. 'Nelson KW, Ege JF, Morwich R, Woodman LE, Silverman L (1943): Sensory response to certain industrial solvent vapors. J Ind Hyg Toxicol 25:282-285. 4Punte CL, Gutentag PJ, Owens EJ, Gongwer LE (1963): Inhalation studies with chloracetophenone, diphenylaminochloroarine and pelargonic morpholide-11. Human exposures. Am Ind Hyg Assoc J 23:199-202. 'Punte CL, Owens EJ, Gutentag PJ, Arsenal E ( 1963): Exposures to orthochlorobenzylidene malonitrile. Arch Environ Health 6:366-374. 6McNerney JM, Schrenk HH (1960): The acute toxicity of cyanogen. Am Ind Hyg Assoc J 21:121-124. 750 Roach and Rappaport 7Barthelemy HL (1939): Ten years' experience with industrial hygiene in connection with the manufac- ture of viscose rayon. J Ind Hyg Toxicol 21:141-151. 'Kranenburg WRH, Kessener H (1925): Hydrogen sulphide and carbon disulfide poiioning. Gewerbehyg Unfallverhut (NF) 2:348. (Quoted in Division of lndustrial Hygiene (1941): Hydrogen sulfide: Its toxicity and potential dangers. Pub1 Health Rep 56:684-692.) 'American Industrial Hygiene Association (1965): Hygienic guide series-iodine. Am Ind Hyg Assoc J 26:423 -426. "Silverman L, Schulte HF, First MW (1946): Further studies on sensory response to certain industrial solvent vapors. J Ind Hyg Toxicol 28:262-266. "McGee WA, Oglesby FL, Raleigh RL, Fassett DW (1968): The determination of a sensory response to alkyl 2-cyanoacrylate vapor in air. Am Ind Hyg Assoc J 29:558-561. I2McLaughlin AIG, Milton R, Perry KMA (1946): Toxic manifestations of osmium tetroxide. Br J Ind Med 3:183-186. "Griswold SS, Chambers LA, Motley HL (1957): Report of a case of exposure to high ozone concen- trations for two hours. Arch Ind Health 15: 108-1 10. I4Challen PJR, Hickish DE, Bedford J (1958): An investigation of some health hazards in an inert-gas tungsten-arc welding shop. Br J Ind Med 15:276-282. "Stewart RD, Baretta ED, Dodd HC, Torkelson TR (1970): Experimental human exposure to vapor of propylene glycol monomethyl ether. Arch Environ Health 20:2 18-223. I6Kinnigkeit G (1962): Untersuchungen selenexponierter Arbeiter eines Gleichrichterwerks. [Investiga- tion of workers exposed to selenium in a factory producing rectifiers.] Z Hyg Grenzgelbiete 8:350-362. "Drinker P, Yaglou CP, Warren MD (1943): The threshold toxicity of gasoline vapor. J Ind Hyg Toxicol 25:225-232. '*Davis A, Schafer LJ, Bell ZC (1960): The effects on human volunteers of exposure to air containing gasoline vapor. Arch Environ Health 1 :548-554. "Stewart RD, Dodd HC, Baretta ED, Schaffer AW (1968): Human exposure to styrene vapor. Arch Environ Health 16:656-662. "Lewis CE (1959): The biological effects of vanadium-11. The signs and symptoms of occupational vanadium exposure. Arch Ind Health 19:497-503. *'Zenz C, Berg BA (1967): Human responses to controlled vanadium pentoxide exposure. Arch Environ Health l4:709-7 12. '*Baretta ED, Stewart RD, Mutchler JE (1969): Monitoring exposures to vinyl chloride vapor: Breath analysis and continuous air sampling. Am Ind Hyg Assoc J 30537-544. APPENDIX C. Documentation of 1976 TLVs Based Upon References to Human Experience: Hazard-"Narcosis" Air concentration Individuals Organ Substance Exposure TLV (Exposure/TLV) affected affected Chloroform' 17-237 ppm 25 ppm 3.1-9.5 9/10 Brain 21-77 ppm 25 PPm 0.8-3.1 8110 Brain Methyl cellosolve* 61-3,960 ppm 25 ppm 2.4-158 6/38 Brain Methyl chloroform3 560 pprn 350 ppm 1.6 415 Brain 520 pprn 350 ppm I .5 517 Brain 490 ppm 350 ppm 1.4 717 Brain 440 pprn 350 ppm 1.3 617 Brain Per~hloroethylene~ 104 ppm 100 pprn 1 .o 216 Brain 96 PPm 100 ppm 1.o 218 Brain 'Challen PJR, Hickish DE, Bedford J (1958): Chronic chloroform intoxication. Br J Ind Med 15: 243 -249. *Zavon MR (1963): Methyl cellosolve intoxication. Am Ind Hyg Assoc 3 24:36-41. 'Stewart RD, Gay HH, Schaffer AW, Erleg DS, Rowe VK (1969): Experimental human exposure to methyl chloroform vapor. Arch Environ Health 19:467-472. 4Stewart RD, Baretta ED, Dodd HC, Torkelson TR (1970): Experimental human exposure to tetrachlo- roethylene. Arch Environ Health 20:224-229. Analysis of Threshold Limit Values 751 APPENDIX D. Documentation of 1986 TLVs Based Upon References to Human Experience: Hazard-"Impairment of Health" Air concentration Individuals Organ Substance Exposure TLV (Exposure/TLV) affected affected Acetonitrile' 160 ppm 40 PPm 4.0 112 Lungs 80 PPm 40 PPm 2.0 0/2 - 40 PPm 40 PPm 1.o 1/3 Lungs Carbon 20 PPm 10 PPm 2.0 16/16 CNS d i ~ u l f i d e ~ , ~ 3-26 ppm 10 PPm 0.3-2.6 531100 CNS < 10ppm 10 PPm < 1.0 391100 CNS Chlorine 0-2 ppm 0.1 ppm 0-20 25/69 Lungs d i ~ x i d e ~ , ~ < 0.1 ppm 0.1 pprn < 1.0 7/12 Lungs Chlorodipheny16 0.1 mg/m3 1 mg/m3 0.10 1/14 Skin ~yclonite~ 0.28 mg/m3 1.5 mg/m' 0.19 0/558 - Fluorides.9 2.81 mg/m3 2.5 mg/m3 1.1 17/74 Bones 0.14-3.13 mg/m3 2.5 mg/m3 0.6-1.25 481189 Bones Hexane" 500 ppm 500 ppm 1.0 0/10 - Lead" 5.0 mglm: 0.15 mg/m3 33 27128 Bloodikidney . 2.0 mg/m 0.15 mg/m3 13.3 24131 Bloodikidney 1.0 mg/m3 0.15 mg/m' 6.1 56/69 Blood/kidney 0.5 mg/m3 0.15 mg/m3 3.3 15/32 Bloodikidney 0.14 mgim' 0.15 mg/m3 .93 21/143 Blood/kidney Magnesium 5.8 mg/m3 10 mg/rn3 . 0.6 114 Lungs oxide fumeI2 4.1 mg/m3 10 mg/m3 0.4 2/4 Lungs Mangane~e'~ 6.23 mg/m3 5 mg/m3 1.25 15/373 CNS Mercury 0.09 mg/m3 0.05 mg/m' 1.6-2.0 0/21 __ ' ~ mg/m3 ( ~ n o r g a n i c ) ' ~ -0.08 0.05 mg/m3 1.6 1/15 CNS 0.004-0.022 mg/m3 0.05 mg/m3 0.2-0.6 0118 - 0.40 mg/m3 0.05 mg/m3 8.0 115 CNS 0.27 mg/m3 0.05 mg/m3 5.4 6/26 CNS 0.19 mg/m3 0.05 mg/m3 3.8 811 1 CNS 0.13 mg/m3 0.05 mg/m3 2.6 9/32 CNS 0.08 mg/m3 0.05 mg/m3 I .6 2/11 CNS 0.04 mg/m3 0.05 mg/m' 0.8 013 CNS 0.02 mg/m3 0.05 mgim' 0.4 119 CNS 2.0 mgim' 0.5 mg/m3 4.0 5/6 Headache/CVS 0.1 mg/m3 0.5 mgim3 1.4 lOil0 Headache/CVS 0.5 mg/m3 0.5 mg/m3 1 .o 611 HeadacheiCVS 0.36 mg/m3 0.5 mgim' 0.72 718 Headache/CVS Di-sec-octyl- 1.7-66 mg/m3 5 mg/m3 0.34-13.2 691141 CNS phthalate'' Propylene glycol 1.35 ppm 0.05 ppm 21 616 CNS dinitrate" 0.26 ppm 0.05 ppm 5.2 6/12 CNS 0.1 ppm 0.05 pprn 2.0 113 CNS 0.01-0.03 ppm 0.05 ppm 0.2-0.6 0/3 - Quartz2"*' 0.05 mg/m3 0.1 mg/m3 0.5 233/784 Lungs Sulfur 1 PPm 2 PPm 0.5 0/3 dioxide22 0.3 ppm 2 PPm 0.15 0/3 - Sulfuric 3-16.6 mglm' 1 mgim' 3-17 51/63 Lungsiteeth aCid23,24 < 0.8-2.5 mg/m3 1 mgim3 0.8 -2.5 9/15 Lungdteeth 0.35-0.5 mg/m3 1 mg/m3 0.35-0.5 0115 - TetrylZ5 1.5 mg/m3 1.5 mg/m' 1.o 50/ 1,182 Skin Toluene26 800 ppm 100 ppm 8.0 3/3 Blood/CNS 600 ppm 100 ppm 6.0 3/3 BloodlCNS 400 ppm 100 ppm 4.0 313 Blood/CNS (continued) 752 Roach and Rappaport APPENDIX D. Documentatian of 1986 TLVs Based Upon References to Human Experience: Hazard-"Impairment of Health" (continuad) Air concentration Individuals Organ Substance Exposure TLY (ExposureiTLV) affected affected Toluene*6 300 ppm 100 ppm 30 313 BloodiCNS (continued) 200 ppm 100 ppm 20 313 Blood/CNS 100 ppm 100 ppm I .o 113 BloodiCNS 50 PPm 100 ppm 0.5 112 Blood/CNS 'Pozzani UC, Carpenter CP, Palm PE, Weil CS, Nair JH (1959): Mammalian toxicity of acetonitrile. J Occup Med 1:634-642. 'Kleinfeld M, Tabershaw IR (1955): Carbon disulfide poisoning. J Am Med Assoc 159:677-679. 3Rubin HH, Arieff AJ, Tauber FW (1950): Carbon disulfide 11. A follow-up clinical study of low grade exposures. Arch Ind Hyg Occup Med 2529-533. 'Gloemme J , Lundgren KD (1957): Health hazards from chlorine dioxide. Arch Ind Health 16:169-176. 'Ferris BG, Burgess WA, Worcester J ( 1967): Prevalence of chronic respiratory disease in a pulp mill and a paper mill in the United States. Br J Ind Med 24:26-37. 'Meigs JW, Albom JJ, Kartin BL (1954): Chloracne from an unusual exposure to arochlor. J Am Med ASOC 154:1417-1 4 18. 7Hathaway JA, Buck CR (1977): Absence of health hazards associated with RDX manufacture and use. J Occup Med 19:269-272. 'Denyberry OM, Bartholomew MD, Fleming RBL (1963): Fluoride exposure and worker health. Arch Environ Health 6 3 0 3 -5 1 I . 'Largent EJ (1961): "Fluorosis." Columbus: Ohio State University Press. "Nelson KW, Ege JF, Ross M, Woodman LE, Silverman L (1943): Sensory response to certain industrial solvent vapors. J Ind Hyg Toxicol 25:282-255. "Tsuchiya K, Harashima S (1965): Lead exposure and the derivation of maximum allowable concen- trations and threshold limit values. Br J Ind Med 22:181-186. '*Drinker P, Thompson RM, Flinn JL (1927): Metal fume fever: 111. The effects of inhaling magnesium oxide fume. J Ind Hyg 9:187-192. '3Schuler P, Oyanguren H, Maturana V, Valenzuela A, Cruz E, Plaza V, Schmidt E, Haddad R (1957): Manganese poisoning. Ind Med Surg 26: 167-173. I4Danziger SJ, Possick PA (1973): Metallic mercury exposure in scientific glassware manufacturing plants. J Occup Med 15:15-20. "McGill CM, Ladd AC, Jacobs MB, Goldwater LJ (1964): Mercury exposure in a chlorine plant. J Occup Med 6:335-337. I6Bidstrup PL, Bonnell JA, Harvey OG, Lockets S (1951): Chronic mercury poisoning in men repairing direct-current meters. Lancet 2:856-861. "Trainor DC, Jones RC (1966): Headaches in explosive magazine workers. Arch Environ Health 12: 231-234. 'XMilkovLE, Aldyreva MV, Popova TB, Lopukhova KA, Makarenko YL, Malyar LM, Shakhova TK (Jan. 1973): Health status workers exposed to phthalate plasticizers in the manufacture of artificial leather and films based on PVC resins. Environ Health Perspect 14:175-178. "Stewart RD, Peterson JE, Newton PE, Hake CL, Hosko MJ, Lebrun AJ, Lawton GM (1974): Exper- imental human exposure to glycol dinitrate. Toxicol Appl Pharmacol 30:377-395. "ThCriault GP, Peters JM, Johnson WM (1974): Pulmonary function and roentgenographic changes in granite dust exposure. Arch Environ Health 28:23-27. "ThCriault GP, Burgess WA, Di Berardinis LJ, Peters JM (1974): Dust exposure in the Vermont granite sheds. Arch Environ Health 28:12-17. **WeirFW, Stevens DH, Bromberg PA (1972): Pulmonary function studies of men exposed for 120 hours to sulfur dioxide. Toxicol Appl Pharmacol 22:319. *'Amdur MO, Silverman L, Drinker P (1952): Inhalation of sulfuric acid inert by human subjects. Arch Ind Hyg Occup Med 6:305-313. *'Malcolm D, Paul E (1961): Erosion of the teeth due to sulphuric acid in the battery industry. Br J Ind Med 18:63-69. Analysis of Threshold Limit Values 753 25Bergman BB (1952) Tetryl toxicity: A summary of ten years’ experience. Arch Ind Hyg Occup Med 5:lO-20. %on Oettingen WF, Neal PA, Donahue DD, Svirbely JL, Baerstein HD, Monaco AR, Valaer PJ, Mitchell JL (1942): “The Toxicity and Potential Dangers of Toluene, With Special Reference to Its Maximal Permissible Concentration.” Publ. Health Bull. 279. Washington: Government Printing Office. APPENDIX E. Documentation of 1986 TLVs Based Upon References to Human Experience. Hazard-“Irritation” Air Concentration (Exposure1 Individuals Organ Substance Exposure TLV TLV) affected affected 1,006 ppm 750 ppm 1.34 719 EyeslURTlbrain 100 ppm 750 ppm 0. I3 014 - 500 ppm 750 ppm 0.67 014 - Ally1 alcohol3 25 PPm 2 PPm 12.5 515 Eyeslnose 12.5 2 PPm 6.3 717 Eyeslnose 6.25 2 PPm 3.1 316 Eyeslnose 0.78 2 PPm 0.4 216 Eyeslnose Camphor4 59 mg/m3 12 mg/m3 4.9 416 URT Cyanogen’ 16 PPm 10 PPm 1.6 717 EyeslURT 16 PPm 10 PPm 1.6 517 EyeslURT 8 PPm 10 PPm 0.8 015 EyesIURT Ethyl acetate‘ 400 ppm 400 ppm I .o 10110 EyeslURT Ethyl alcohol’ 1,300- 1,900 inglm’ 0.68-0.89 313 EyeslURT 1,700 mg/m3 Ethyl ether‘ 300 ppm 400 ppm 0.75 10110 URT Propylene glycol 95 ppm 100 ppm 0.95 416 URT monethyl ether8 47 ppm 100 ppm 0.47 011 URT Selenium’ 0.007-0.05 0.2 mglm3 0.035-0.25 9162 EyeslURT mgim3 1,1,2-Trichloro- 669 pprn 1000 ppm 0.67 0/50 - 1,2,2,Tri- fluoroethanel’ ‘Raleigh RL, McGee WA (1972): Effects of short, high-concentration exposures to acetone as determined by observation in the work area. J Occup Med 14:607-610. *Di Vincenzo GD, Yanno FJ, Astill BD (1973): Exposure of man and dog to low concentrations of acetone vapor. Am Ind Hyg Assoc J 34:329-336. 3Dunlap MK, Kodama JK, Wellington MD, Anderson MD, Hine CH (1958): The toxicity of ally1 alcohol. AMA Arch Ind Health 18:303-311. 4Gronka PA, Bobkoskie RL, Tomchick GJ, Rakow AB (1969): Camphor exposures in a packaging plant. Am Ind Hyg Assoc J 301276-279. ’McNerney JM, Schrenk HH (1960): The acute toxicity of cyanogen. Am Ind Hyg Assoc J 21:121-124. ‘Nelson KW, Ege JF, Monvich R, Woodman LE, Silverman L (1943): Sensory response to certain industrial solvent vapors. J Ind Hyg Toxicol 25:282-285. ’Lester D, Greenberg LA (1951): The inhalation of ethyl alcohol by man. I Industrial hygiene and medicolegal aspects. 11. Individuals treated with tetraethylthiuram disulfide. Q J Stud Alcohol 12: 167- 178. ‘Stewart RD, Baretta ED, Dodd HC, Torkelson TR (1970): Experimental human exposure to vapor of propylene glycol monomethyl ether. Arch Environ Health 20:218-223. ’Kinnigkeit G (1962): Untersuchungen selenexponierter Arbeiter eines Gleichrichterwerks, [Investigation of workers exposed to selenium in a factory producing rectifiers. J Z Hyg Grenzgebiete 8:350-362. “Imbus HR, Adkins C (1972): Physical examinations of workers exposed to trichlorotrifluoroethane. Arch Environ Health 24:257-261.