Document KGEBZBYGm53Q0dngMOB2x18w2

S'rvunty mghi pans of suit.' by side charcoal tube and 3M Brand " passive vapor monitor samples were taken in the field and analyzed for 22 organic chemicals including trichloroethylene, benzene, toluene. MEK. m . p . and o aylenes, isopropanol, and several C5 through C8 alkanes Sixty four pairs were personal and fourteen pairs were area samples Linear regression analyses were performed for ten chemicals detected over a sufficiently large range of concentrations Satisfactory correlation (r 0 90 and slopes not significantly different from 1 0) was found between monitors and tubes for n-hexane. methylcyclopentane. toluene. 2 methylpentane, 3 methyl pentane, n-heptane, n-pentane, and isopentane. Tube and monitor results differed tor methylcyclohexane and n octane Paired t tests were performed on the remainder of the chemicals, and no consistent significant differences (5% level) in the means were found. Field comparison of charcoal tubes and passive vapor monitors with mixed organic vapors JOHN l S IIK.KEY Pb 0 . P h anil CAROLYN C BISHOP University i)l North Caiulina Ocruiianunul Health Studies Group, School ol Puhhi Health ( hiipi l Hill NC i /SI 4 introduction Svvciul hiands ol charcoal-adsorption passive vapor momlots have been marketed recentl>. these momtois hold mueli atliaelion loi measuring workplace sapor exposutes because the\ ate lightweight, require no povvet. pump, or luhing anil aie mu likely to imerlere with woikcis" uiovcmeiils I lie upeialtiig pimeiples ol these momtois have been deseiibed. and then advantages and limilalions have been eompaied to those ol ehareoal tube pump momlormg svstenis 1 1 the peiloimanee ol passive momtois lias been ev.limited loi v ai ions ehemieais nmlei vai ions conditions How cv cl. held st mites ol 1 lie pet lot manic ol passiv c num iloi s in assav mg mi seil organic v apoi s are lack mg. alt hough an evleusiv e held i ompai ison ol passive monihu s a mi i lui coal lubes is planned.'' procedures Sevcutv-eight sets ol simullaneous ehaieoal lube ami 7M Brand It.15(10 organic vapor momtoi samples weic lollccied and anal\/ed lor 22 organic chemicals as pari ol a survev ol lire inamilaeluunglaeiliiics I heebemieals. listed m I able I. were selected lor analysis on the basis ol then pic'cncc m materials used in tire manulacture Samples were collected during regular work shills m two plants timing two 2-day periods in .Inly and August. Id7d Stxty-lmtr seis were personal samples and 14 weic a tea samples. I he sampling pettods varied Imnt thiee to live hours Charcoal tubes were usually changed during the sampling period to reduce the possibditv ot overloading, the monitors were not. I bus. with tew exceptions, each pan ol tesults consists ol the eoneenttation front a single monitor and the time weighted average concentration Irom two ehaieoal t u hes 2$4 chemical analysis Allci exposure to the solvent vapors, the otgante vapor monitors and ehareoal tubes weic capped and stoied .it C until time ol a Italy sis Monitors were anal v /cd m accordance with the manulaetuier's msiruetions. using a i'cikm- I Intel e,]s ilitomalogtaph I Model Sigma 1 I equipped with a llamc lom/alton deteetot, Coneeuualum data wete i.tlculatcd with a I'eikm-I Intel Sigma Hi data svsiem I lie desot pi ion el In lem v lor each solvent was determined bv om lahoiuioiv using ihe method teeommemled bv the 7M ( omp.inv t om cut l at ion-, vveie tabulated m ,n eoi dative with ilia mil.n I in ct s mstiuctions I lie ddlusum hiit)iis 01 "v( inij'lmu ttti ' I ailalagous lo ddlusum loelhiientsl useil ale listed m I able I loi each chemical l It.1110.11 tubes were desoibed m the siandaid manner and attaly/ed mulct the same pioecdmcs as the monilois results I ell ol the ehemieais vvere detected ovei a sulhcicntly wide langc ol loiuentiahons in one 01 both plants lo pet nut a lineal icgicsston analvsis ol passive momtoi and ehareoal tube sampling tesults Slopes, intercepts, eoiielatum coellieients and dG , eonlidenee inteivals lot pu-duiion ol indi vidual v allies ' ,ue given m I able II. sep.ualelv tor the two smvevs and lor the combined data Irom both groups. Char coal tubes weic (\ I values and momtois were (Yl values, that is. eh.iivo.il tube sample results vvere considered to relied "mu- eoneentiatioits. as a basis toi comparison I he second column in I able II indicates the range ol concentrations I on nil m the samples Columns 7 and 4 are the slope and 't -intercept ot the hne.tr regression line, w Inch indicates how well the two methods agree Aslope ol I (land at \ -inleieepi ol /cm indicate close overall agreement ' I lie eortelalioti loellieient (column .*>> relleets the degree ol 3M 101206 A'r' ir,1 4jKf' ftp- 1981 TABLE I Chemical! Analyzed and Sampling Rates Ch?mif.*l Sampling Rata* imL mini* ft Pl'hlittll' ii ? M"ihvip'ntrtO<f n H>k,ini> ( yt Io|m*iu,m>* MiMhyli y< tup^nlimr n (..yi iuhi'xjiic MifiMyli yrlohexane n Ounne 1 1 1 T f irhloroethan** Methyl uthyl ketone Isopr op.Tnol Ben/ent' TrM.hloroethylpne ToUien* Ethylene dtrhloruJe p Xylene m Xylene 0 Xylene 29 8 29 8 28 2 28 2 28 2 28 2 2B 2 28 2 27 7 28 2 27 2 21 8 28 1 31 2 35 9 33 0 28 0 30 4 32 1 23 7 25 6 25 7 `Reference #6 departure ol daia-pairs Irom the repression line. An r value 01 I 00 indicates near perfect correlation, and lower r values indicate poorer correlation. The last two columns are the predicted 95 rl confidence limits of an individual passive moni tor sample, given some "true" concentration of X as indi cated by charcoal tube samples. 1 he predictions were made lor concentrations at the fop of the data range observed I he other twelve chemicals were delected in compara tively few samples or mostly at low concentrations (less than I ppm), so no linear regression analyses were performed Instead, the paired l-test1 1 was used to determine il the monitor and tube sample means were statistically different at the 0.05 probability level, assuming normal distribution No consistent difference in means was demonstrated except lor n-oclane. discussion I he data in Table II show two trends. In Group No. I. for every chemical except n-heptanc the passive monitors show highci vapor concentrations than the charcoal tubes, as indicated by linear regression slopes greater than 1.0. In three cases (toluene, n-octanc and methylcyclohexane) the slopes were significantly different at the 95ri confidence level from the ideal slope of 1.0. The observation of higher concentrations from passive monitors than from charcoal tubes is not unique. In one report.""1 acrylonitrile was moni tored with 18 Gasbadges,M and charcoal tubes side-by-side; the badges averaged 2.73 ppm and the tubes 2.14 ppm. a mean difference of 25 percent. The second trend was that Y-intercepts for nearly all chemicals in all groups were very close to zero (less than I ppm), and were in the main negative. Although a slight negative intercept is of little importance in monitoring sub stances with relatively large Tt.Vs. it may indicate a detec American Induilnai Hygiene Association JOURNAL 14?) 4 8! tion threshold or lack ol sciisitiv n\ in tnc passive momioi s ,n \er\ low concentrations Such a condition, ii n'liiumcd should be considered in making decisions on the u*c oi passive monitois lor detection ol substances with 11 \ s m the I ppm range or lower ( ouclation coefficients til lot sevcial ol the subsumes were 0 94 ot highei I lie 95 percent prediction linin' on mdiv idual passiv e momioi sample concentrations ate show n in lahlell lot given chemical concentrations I lie predicted monitor concentrations aic geneiallv within 4 25 pciceni id the reference cnnccnlialmiis. m Group No 2 and the ionibmed data, bul varv widelv in Gioup No I because ol the high slope values Ibis ptcdivubilui would be much improved by use ot the regression curve to "calibrate" the monitors. Howcv er. u is presumed I hat t he cun c vv ill not be known a priori. II the slopes lor am chemical had consist ently varied from 1.0 appreciably in both groups (as with n-octane and methylcyclohexane). an inaccurate "wi/ii/'/we rate" lor diffusion published by the passive monitor manu facturer might be responsible. For the statistical analysis, chat coal tube sampling results were presumed to reflect the true concentrations, and be sublet to much less variation than the passive monitois 1 his is by no means a certainty. How vv ei. statistical analy ses where both methods are suhiect to error are rather compli cated' 1" and the method used here is considered to be satis factory lor this purpose." sources of error Several possible sources ol errors in the results of this study are discussed below. I. I he "sampling rates" used with the monitors may he imprecise I hese sampling rates are analagous to diffusion coefficients. Published sampling rates were used where available; the others were estimated on the basis ot chemical similarity. Use of too low a sampling rale would increase the slope cb) ol the regression line in inverse proportion to the sampling rate error, but would not alleet the correlation coef ficient I his result was observed with met h\lev dohexane. raising the possihiluv that the estimated "sampling rate" used (27.2 ml min) was too low, Ise of too high a sampling rate would lend to depress slopes in inverse proportion to the error. I Ins type ol systematic error could account for regression line slopes tending to he consistently greater than I 0. 2 I here may have been interference Irom unknown chemicals. Many small unidentified peaks were present in some of the chromatograms. Such inter ference would have affected tubes and monitors similarly 3. On-site temperature and pressure departures Irom 29K C and 760 mm were not corrected, I hey were presumed to alfect monitors and tubes equally except for the temperature correction' ' to the samphngrate(T"K 298)1 ' 1 his could cause differences in monitor results ranging from -3 to +5 percent, as 26b 3M 101207 TABLE II Compart* n I Results of Simultaneous Sampling hy Passive Monitors and Charcoal Tubes Chemical Range of Data (ppm) Linear Regression Slope & V Intercept 95% C L (ppm) Correlation Coefficient in 95"i Prediction Interval tor Passive Monitor Sample at T rue Concentration X Monitor Sample X (ppm) ippml Group No 1 130 sample pairs) ii Hexane 0 37 Methylcyclopentane 0 17 Toluene 0 18 n Octane 010 2 Melhylpenlane 0 18 3 Melhylpenlane 0 30 n Heptane 0-7 Methylcyclohexane 07 n-Pentane 06 Isopentane 0 13 i 02 0 12 1 11 0 13 1 31 0 12 1 41 0 15 1 10 0 16 1 13 0 16 0 94 0 13 1 33 0 30 1 29 047 1 12 0 68 0 50 0 72 0 36 0 01 0 50 061 0 31 004 001 0 92 0 96 0 96 0 97 0 96 0 C 94 0 94 0 86 0 73 0 54 40 ,n 6 to 4p b 2o I8.il! 24 6 20 23 211- 28 6 10 12 On- 16 2 20 17 7 m25 5 30 2 7 0 u- 39 5 10 7 3 lb 10 9 10 9 7 lo 16 9 10 7 9 io 1 7 9 10 3 4 io 20 9 Group No 2 (48 impl pairs! n Hexane 0-27 Methyicyclopentane 0-20 Toluene 0 20 2 Methylpcntane 0 16* 3 Methylpentane 0 30 n Heptane 0 251 MethylcyclohL.ane 0-20 n Pentane 0 30' Isopentane 0-40" 091 ' 0 10 0 99 0 1 1 0 97 0 10 0 92 0 07 091 r 0 05 1 09 0 13 1 39 0 13 0 93 - 0 07 1 06 0 03 0 11 0 26 0 16 004 -0 02 0 56 0 15 0 05 0 17 0 94 0 94 0 97 0 97 0 98 0 93 0 96 0 97 0 99 25 17 9 lu 27 b 20 16 1 io 22 9 20 16 6 to 22 4 20 16 2 to 20 6 30 24 6to 30 0 25 22 2 io 31 0 20 24 3 io 31 0 30 24 1 to 31 3 40 40 4 io 44 2 Combined Date (78 sample pairs) n-Hexane 0 37 Methyicyclopentane 0 20 Toluene 0 20 2-Methylpentane 0 18 3- Methylpentane 0 30 n Heptane 0 25 Methylcyclohexane 0 20 n Pentane 0 30 Isopentane 0 40 0 97 0 07 1 03 0 08 1 09 0 08 0 99 ' 0 07 1 01 0 06 1 07 0 10 1 38 - 0 1 1 0 92 0 07 1 06 - 0 08 0 26 0 38 0 06 0 09 0 15 0 53 0 12 0 15 0 31 0 95 0 95 0 95 0 95 0 97 0 93 0 94 0 95 0 94 40 33 5 to 43 9 20 17 6 to 23 6 20 19 0lo 24 6 20 17 1 to 22 5 30 26 4 to 33 8 26 22 7 to 29 7 20 24 4 to 30 6 30 24 3 to 31 3 40 37 2 to 47 9 'Only 21 pairs 1 ppm Only 1 & pairs 1 ppm thy tcmpcnitures at sampling sites were indeed to range from 5 11C below to 10 `C abuse 25 ' (' 4. Overloading ol lubes and monitors could cause errors, ('harenal tubes sampled Irom 90 to 190 liters ol air. averaging 150 liters, at I I. mm. Only two chareoul tubes showed concentrations over 100 ppm total organic vapors assayed (120 ppm and 150 ppm) These two tubes indicated 2X and 45 ppm total vapor respectively in their back charcoal sections. Tor other tubes, the total collected in the back sec tion was less than 25 percent ol that in the troni section. Each monitor was exposed as long as both tubes in a set. Any significant overloading ol moni tors would result in regression line slopes substan tially below 1.0. This did not occur 5. The back section of a tube was analysed whenever the chromatogram of the front section showed rather high peaks. In essence, the backs were analyzed if total organic vapors assayed exceeded about 50 ppm, which occurred in roughly halt the samples. It is possible that a portion of vapors collected in the tubes was missed in analy/mg samples Irom areas with low sapor concentrations. This would tend to increase regression line slopes slightly and gi\c sub stantially positive Y intercepts I he latter did not occur 6 I uhes were analv/ed 12 weeks alter sampling, and monitors 17 weeks. All were kept at -7 "(' in the interim This delay may have resulted in loss of collected vapors. One could speculate that migration ol vapors to the hack sections ol charcoal tubes during storage might account lor some loss m lubes whose hack sections were not assayed. Tosses in the monitors might be less as the vapors would have no alternate sink. Such migration would tend to in crease regression line slopes slightly It is the ludgment of the authors that the potential errors did not significantly aflcci the results. significance of findings Since observed concentrations of substances were generally far below T1 Vs and permissible exposure limits < PF1 s). no 3M 101208 Am ln<3 Hvp Assoc Apm )98i i HIP. III 'lull' Cl II lit dl.l W ll 11 Oil I I lit SC ll.lt.I Icy.llllllll. IHI ll'ld* tiuii nt iiuimiiiii .nut lulus .it iniiicntuilinns approaching I I \ s, willumi assiimiiiy 11 iil.i 111 \ hc\ limit hi-nhsci veil data liimm'i. diiic mu' hi I In- a nt hi pat cil values nl I hi' passive miiiiiim in in iiiiiiiiu' mi.mluuii". u is impmtaiii Ik dcmmi strati' tliai thev i.in ichahlv iiii'.imiii- low iwpnsmi's as well a* Iii^Ii mu's, I In- ii'Mills nl tins siiuiv mdicalc that I In' p.i'siw llllllllllir Il'Il.lhK .|NN.I\l`ll IlIW llllll'l'MlI.IIIKIIs III llll Si'll sapors nl 20 nl the chemical' mentioned egnallv as sstll .in chaicoal tubes, undei the conditions cmnunicied l liarmal tube and pasMsi' iniuiitoi it'sidls dltlcrcd Mfimliialllls Ini mi'tliv'Icvelohexunc anil n-ocljnc I hi- Icndi'iiiv unsaid negative Y-inti'iccpts I I able 111 mas indicate a sub-ppm deliclinii llui'shold in ihi' nininlors lor siiiiii* chemicals Mmi' such coniparatisc studies arc needed to build a body ol Ineiature on which to establish the applicuimns and limitations ol the passive monitor. r search support I his research was supported by United Rubber Workers Union, inestone I ire and Rubber Co., Ihe (iencral lire and Rubber Co.. Goodyear lire and Rubber Co., and Uni royal. Inc. references 1 Tompkins. F.C . Jr and R L. Goldsmith A ew Personal Dosimeter for the Monitoring ot Industrial Pollutants Am Ind Hyy Assoc J 38 371 (1977) 2 Bamberger. R.L . G G Esposito. B W Jacobs, G.E. Podolak and J F Mazur A New Peisonai Sampu't toi Organic Vapors Am Ino H\i; Ass,1. 39 70! .1978' J Woebkenberg. M L i i.ueni N.PSH Research on Passive Dosimeters In Pro, ol the Simpasuim on the DeiO'OPmcnr oihl Usage id Pots,mat Mon ims tor E iposwo .mo Ho,dm Ehoits Studios US F Iiviiiiiuii.-niul Protection Agency ResoarcnTrianiiloP.uk Ni 2 771 1 Pi.lilu atmn E PA 600 9 79 032 iJuno 19791 4 Hirayama. T and M Ikeda Aooi>. ability ot Artivated l a' lion f ell to t lie Dosui ion \ ol Solvent Vapt Module Am Ino Hyy Assm J AP 1091 .1979' 5 3M Btond Ury.iiii!' V .1/10/ M,>no,ir Pipoui 1 Information am; Usage Gmtlo Oi 1 upationai He.ntn and Satelv Piodui ts Div ision 3M ('ommpany tundaied. 6 Compound Gmdv tm 3M n3b0{) Oryamc \ opor Momtoi 3M Conipany (Eeburary 19791 7 Remington. R D and M A Scbork Statistics with Appli cotmns to the Bio/ppical anti Health Si ton. os Prentice Hall Inc Englewood Clifts. NJ(1970i 8 Natrella, M G t iporimotualStatistics National Bureau ot Standards Handbook 91 (1963) 9 U S, Environmental Protection Agency Guidance tor Selecting TSP Episode Monitoring Methods Research Tri angle Park, NC 2771 1 Publication No EPA 4b0 A 79 007 (Febroary, 1 979) 10 Silverstein. E G. Validation ol Aticor GASBADGE1" tor Acrylonitrile and Improved Desorption Efficiency Am Ind Hyg Assoc J 38 412 11977) 11 Acton, F S. Analysis o/Siroighi L mo Dot.i Jonn Wiley and Sons Inc . New York, NY 11959i 12 Neter. J and W. Wasserman Applied Linear Statistical Models Richard D Irwin Inc , Homewood ILI1974I 13 ACGIH Threshold Limit Values lor Chemical Substances and Physical Agents in the Worlnoom Environment with Intended Changes lor 1979 Am Conf ol Governmental Industrial Hygienists Cincinnati OH 45201 (1 979) Amrncan Inominai Hy^.ene A"uti3tiun lOUWNAi HI 3M 101209 267