Document NEOGZEmv4GrOM9O4E5ED4ebwg

Kcpraued :r jiu AMERICAN l.NDLsTKIAL HYGIENE ASSOCIATION JOURNAL Volume JO. Novemoer-December, 1969 Monitoring Exposures to Vinyl Chloride Vapor: Breath Analysis and Continuous Air Sampling EDUARD D. E.ARETTA.* RICHARD D. STEWART. M.D..* and JOHN E. MUTCHLERf Department or Environmental Medicine. Marquette School of Sfedicine. Milwaukee, Wisconsin, ana Environment a, Heattr. Section. Biochemical Researcn Laboratory, Eke D:-a. Ckemica. Compan\ '-.aland, Micr.iqan ^ An environmental survey was conducted to determine the time-weighted average exposure 1 TV. A oi a group ci chemical plant workers to vinyl chloride (VC11 vapor. This survev icaiurea continuous multipoint air sampling and analysis using an infrared soectropnotometer. The inhalation exposure data were digitized and record ed on paper tape for lucseuuer.t tamputer analysis and derivation of daiiv TWA values for each worker. A breatn sampling program was conducted concurrently with the environmental survey, ana a series of breath decay curves relating post exposure breatn concentration to vapor exposure were derived from the data. To validate the breath curves deriven from on-the-job data, postexposure breath curves were also constructed from breatn data obtained following experimental human exposures to carefuilv controlled concentrations of VC1 vapor. The close agreement between postexnosure bream concentrations at the corresponding TWA's obtained by each of me methods suggests mat either continuous air monitoring or breath analysis is vaiid for estimating the worker's individual daily exposure to VC1, and provides further evidence mat breatn anaivsis is a useful industrial hygiene technique for evaluating vapor exposure. Introduction THE QUESTION THAT MAY ARISE lotion mg an cm trenmenta. sutvev :s whether the chemical vapor ;cncep.trav.ons meatmen me truiy rentesentativ e oi tin- <'\- po-mic being gxiji': it'ticcci in c no:-,::'.eti. Ev amatten oi the tansies a: atmesohe::z :an- centrations and estimates ot -.::::e-uevrated average concennattou TWA are a.I too often based on a few -not sammes outained unc.et i ondtltons nnioh are not tcnr.'srnta- tive oi ail phases of a g.vi'u -ratio:'. A more exact meastuenient ot vanor exrosute would have to be be-'cd on contmuoi,s moni torin'.: of ait in workman's hi'-amint: zone ci t it in c nis entile notx si',;:;, Ohviousiv this task is made riittlonit and neon Imno^si'oie Thu pjoer prrsfntrtj ai thr Ami'iican H%nme Conference. St. Louu, Muaoun. Mav lJ-1' Marqueit* School of Mcu.cme, Mjlwu*ce, Wjconun. TXn Dow Gbcmctl f'-Mnoiflv, MidN'M, M'^hicmn. b\ the iatgc number and variety of tasks pet'ormed by todav's modern chemical plant not ker. Recent imptovements in automatic moni torin': and data processing equipment have provided a means lor a more 'atisiactorv sis. iutioti. Sequential samplers and automatic anuiy/ets and recorders can now be used to continuously monitor several locations or operations to provide more valid data on wiiich to base estimates of chemical exposure. Computers can be utilized to manage the large volume of data generated bv continu ous monitoring.1 Meanwhiie a technique lias been under dcveiopment unich more prccisciv derines tinlev ei of individual exposure. Tlie reaiizatic" that tlie total bodv burden of a volatile cne. ical is directly related to its concentration m expired air led to tlie development of tech niques for collecting and analyzing breath samples useful in estimating the more im - V-' i r o mr-. r J V- R&S160531 5J('J Soiembcr-Deccmbcr. 1969 viduaiizea exposure exrjerier.ee or each work man. Studies by Stewart a>. have shown mat me excretion or `'decay ' of vapor in the bream can be used to characterize the ex posure. Breath decav curves constructed for several chemical solvents have proved ciin* icallv useful as an ireex to chemical expo sure. These bread: decav cur.es* for :;;e most rent. 'a ere constructed from postexposure mcam data obtained troru txoenmentai hu man exposures to careiuiiv controlled and re:at:v eiv constant vapor concentrations. However, cream aecav curves have wcenth been constructed from oreatr. data collected fiom workers whose work environment was n-*:::ir continuous.v monitorec In thus jtudv of human exucwurc to vinvi m.once VCI vapor, oreatn aecav curves .cnitructed from data obtam.eu during ex perimental exposures to the reiativelv uni form concentration within an exposure cham ber were comoared wmo tnc^e derived at the dneoreticallv eauai. but brcaalv riuctuatingr, concentrations encountered :n a c.nemicai p.ant atmosphere. A measure of the validity of continuous monitoring ca;a and the use:umws of bream anaivs's :n a^sessinc timeAeiumed average exposure was redacted b\ a c.ose sumlaritv between mo two sets oi worn decav muivrs STat.qn l ipci S'A 7,ON } j i 3TA7.CN cws;ce air . 5 STAT'SN * "AT ON * 7 STATION $ i i SPECTROMETER ` . c.Gitizer :eRceR^ t EXPOSURE SUMMARY Procedures MonitOT'.nq the P'.r.nt Atmosphere The cnemrcai mstailation surveyed was a closed structure housing severai separate chemical processing oDerarions. First, a job survev was conducted for each of four job classifications :o cetermine the work areas frequented ov me workmen and the time they soe.nt lr. each area. F^r earn :ob ciassirication. r.vc sum niinu n: in trie work a;e outside :ne nun 'Tp[ hit? is `a ere p:acea :n me jamming line to a^sur e a cee a a.r reierer.ee. The sample prooes were 5 Ld-mcn I.D. Saran tubinu tnrouou w me:: ur samples were drawn bv a v acuum puma a; a rate of 17.5 liter s min to a cen tiauv .c* eter. T.;.e spec with a j-tuets ;:ve :o z Tjzm 10.63 muerons. ."tCH1* v r tri a t e a imaieiv 1CC0 p; A sen emar.c tem is s r.own .n ecutec : euuer.tu soienoid vaives advance me ui ites. .\ . 'Sun. : wcordec: on a wnue t- e data on pane r tape b ptotjrawmice to iransm.::tnncuw 3-minu; e <nm:w rccotdea in digital form aeriod. I'lte rammittance data furnished be the street: cm'.otome'.er was cons erred to absorb ance and reduced to concentration according to Beer's law: A = Log 7ME-wE'GHTEO MEAN EXPOSURE * 001 N Tr7 P, W*trt C, * "iC" CGnc*n!f3f`Crt at Slfllion i p, * p*f c*n of *im* iptni at location i during normal o** octivitf Figure I. Schematic diagram oi the ;nirareu continuous monitoring system- w 111 i e A .V A" .V -- .'ur.oi t'.iiu e -- nasc-une icsnoii'c. -- re. pome at totai aiwoipuon. = ;-`.wonse at iocation i, = 2. i, 4. 5. b. "J 1 L* American Industrial Hygiene Association Journal Finaiiv. C = KA lli'l v '3*6UHT0 TFfMTGH K ~ a nropot tionaiity constant. C = concentration The tanea data were processed bv a 3urrotarns 5500 corr.Duter at The Dow Guerni ca. ComDanv Comoutntion Researcr. ,,acoratcrv. The ccmtiter v. as used to ca.cuiate the mean and standatd deviation or concen trations at each location tor eacr. a-.tour work shift. Finaiiv, lime-wetgr.ted a-, erase concentrations -aere calculated ;or eacr. job ciassincation .isma tr.e t*rr.ewcca,..r, -d.a obtained from tr.e 'cc survevs. As nercrined eisewnere.- tr.e ..eirntec oercer.tare time ctirin? which concentrations exceeded sev eral nrechosen leveis v-as a.so ccmoutea tor use an establishing exnosure picn.es. F: lure 1 describes the exnosure ironies trectiencv distribution; tor tr.e :c-r ;oo classirications studied during this sun. ev. These pronlvs show tr.e percer.tare tune that concentrations exceeded tr.e .evets shown. Tiiev sttmmarire several tens c; tr.ou-ands of individual,\ measiired concentra tions and reduce them to smaie curves. Fut ure 3 shows the corrective trer.a brought about bv actions unaerta--.cn to renuce the atmospheric concentration of \ C! ov-r the 7-month period ciurina which the stuav -..as conducted. Oniy two job classifications war ranted extensive stuav but men in a.l :our ciassirications were as.-tea to '.true -i.iie .n die hieath sampimtr nrotiram. (3 iic-fab B'caih Satr. run? Tiiree separate bteath samptine piierani' were conducted concurrentiv with tiie envoi onmentai plant sutvev. designated bv tile boxed portions in Fame ' Each worser collected three bteath mmoles daiiv-- tr.e tit St on ids atrtvai nemo :roni wmk. tr.e second 5 to 10 horns later, and a tinai satnpie bolore returnin'-: to woik the lollowittj oa\ I he samples were collected in pipets constructed from shoti Icntrths of 59-mtn suit eiass tuuitur to wiucii bad been weided at cacti end tile threaded nortion at a 5-dram o-tttl rew- W ---- soi ;i ;s j i o :o :o*cio*c:o eo *c ------ju :.y'*iOHr[o % at Twt rt cstiCEttr nation i::i:e3 -*' s-own Figure 2. ExDosure profiles expressed is V P viotjr concentration, versus tr.e exsosure -requr-rv. i'strtbut.on ter tr.e tur 'on ct.isstnca'.tC't'.s can gtass via. Fitjure 4 . Tiie overa.i .etut.. cf the nioet '.-.as anout 9 incr.es. so it cc ;.c. be convenientiv and inconsoicucumconed to and from work in a lunch ouc.-.et Tlie piastic cans were lined with six lave1of Satan dim identical to that used f.'r titconstruction oi Saran ait sampling oac' 3 .32-inch hoie precriiied througn one o; m-.cans provided an access for withdraw mr samuies Tiie Saran liners provided an etfective tras barrier so tr.at vapor tosses were held to iess than 10'T for a hoio.ing pet toe. of 3 aavs. When collecting a samnie the subject waasked to remove the caps, piace the pipe: m his lips, ami breame normailv m trtrotisiit nose and cxiiaie titrotisjtt the pipt-t tin e :Q r- ;:o*- Figure J. Weeklv mean vauor exposure concen trations measured during tile survev. Periods irur uiiich breath samulitur was conducted are rettirsented bv ihe boxcu-m areas. 540 -Vovember-December, 1969 1 J2- Ficcre 4. Glass nice: 30 mii used for cciiect,r.e bream samaies. One can has a areanilea hoie 'or uas sa.nniinsr. Both cans have Saran liners mien seai .ne pme: c.namber. times. After exoeiiing the fourth breath he ouickiv cars the tube, manning a portion of a.veoiar air. Tile irr.cortar.ce of weiring the rarre. date, exact time ot sampling. and the wcr.kshif: most recer.tiv completed. on the iaoei attached to eacr. piper, was stressed. Aliauots were drawn trom the tv.pets with a i-m.i Hamilton gas-tight svrmge and ar.a!. zed in ar. Aerogranh A-600B gas errorratozraon using X; carrter gas anc a nvdrogen name detector. Secaraticr.s were made with a 5-toot. '3-incn I.D. stair.iess-stee: coiumn racked with Carbowax 20M a-.-taiine on Chromosorb W 60'BO m.esn aetd-washed. Exposure Chamber Operation Tiiree experimental human exposures to YC1 were conducted at r.onmai vapor con centrations of 50. 250. and 500 com. The excosure cnamber was a room measuring 41 feet by 6 feet wide by 7.5 feet high. The room had a continuous positive a:r supply and exhaust svstem. capabie of maintaining a slight negative pressure within the chamber. Continuous distribution of tile cham ber air was achieved bv iec.rcuiatmg the air with a suuirrei cane fan m.rougn a -eries of uiiet and outlet ducts cunning tiie length ot the citamoer. T'ue YC1 was metered into die duct can'-inct air exhausted bv :::e squirrel cage far and entered the room aimosohere via die recirculation system at a rate sufficient to maintain tiie desired rtmosohene concen tration. Tiie vapom were introduced from a pressurized storage cv under through 6 teet of 1 a-inch I D stainie-w-'leri tubing into a rotometcr prior to enteiirur the circuiatintr air duct. A hearing tarn* wrapped around the stainiess-steei tubing pi evented condensation of the VC! and stabiii/ed the flow of the \ anor. T'ne concentration of YC1 in the chamber was ronstandv monitored with a TYrkin-F,!- mer infrarsc spectrophotometer eouipped with a 10-meter path-length gas ceil A sam pling probe, consisting of 5/16-inch I.D. Sa ran tubing, was centrailv located during the exposure to represent the breathing zone of ail subjects within me chamber. The orobe was moved about prior to each exDosure to detect imba.ance o: vapor concentrations witr.tn tne cr.amber so that necessary cor rections in tr.e recirculating svstem couid be mace. Air samples collected periodically within the chamber throughout the e.xoosure dav were ar.a.vzed bv gas chromatograohv for ceded assurance of anaivticai accuracy. Both me mtrarec spectropnotometer and the gas chromatogram: were calibrated before each experiment or.c a: intervals m.rcucnout the exposure dav Each 7.5-hour excosure dav included a O.o-hour lur.cn period in an unconcaminated area outside me e.xoosure chamber. The TV A concentration was calculated on the bus's of 7,5 hours ot exoosure. Cu.'tuai ana Laboratory Procedures Each subject nab been under careful medi cal surveillance by tr.e medicai department :or a number of years, and each was given a complete medicai examination a few davs prior to the VC I exoosurcs. Included were a complete urinaiv sis and 24-hotir urine for urobilinogen, complete biood count with sed imentation rate, reticulocyte count. SCOT. .SG1JT. LDH. aikaiine phosphatase. BL'X, creatinine, and biiiruuin, hacn sub wet '(. ei\ed a teueal phvsieal examination 1 hour beiore entering the expnsuie ciiamoer Tills examination included measurement ot lemoeratme. biood pressure, and pmse rate, a neurological examination, and collection of blood and breath samples. A questionnaire noting the presence of anv swnptoms in illness tor example, headache, nausea, dtv throat completed the pre-ex posure medicai evaluation. After the subject entered the chamber, uitai expired breath samples were collected eveiv hour bv having him breathe out through a Saran tube leading to a Saran plastic col lection bag located outside the chamber. Tidal volume and total exniratorv eanaritv ^10025 R&S160534 V American Industrial .-1. iu i ur.i 04 ; aere measured in lire momma me -aa::. .me in me afternoon exposuie nericas. Subjective and neurciozica* icsncr. ;es .-.ere measured before the mmec: Tmrm me chamber. 15 minutes after er.t:ar.ee me at :-ucvr mter'.a.s tnereaiter. . .ar.r.acar. Oooremation and Crawfcra Mar.-a, letter.:-. Tests were conducted a: mlcm.orr. r.i and aaair. in the afternoon. Brent: -am. ;.,r.c ceaan immediate:' attcr trie im-c: .eft the e'mosure chamber A 24-hc:r no;-e':rciare arme sarnoie was coiiectea arc: a b.coa cr.me aas drawn me imiowmr mc.'r.rj :or SG?T, LDH, alkaline prso-mniase. ZiL'N. creatinine, and biliruon detr: mira:: m v Dam rice concentrations were carol: :: -1ero- mr mtnttn.e :ecresi-cn 'iiir.a .......c.ta. _:n- "uter. An em.Diricai re ationm.- me .o.m. Concentration -- TT-\'A. i.m.e as se.ect- Jd from a cr.oice oi -e\erai lams, ea.ii cased on T'A'A and or time. The re-. ..i.r.c : iiop. eciuar.on nest represents :..-e 'uaeiea re- laticnshio between bream \ iro.. m.e:._e con centration, time-weiemted a\i'r:._re exposures, and nostexposure tune. Each breath decav curve uns an cmociuted standard error or reeression ..uiC' can be usee to commute the cmndorce band for anv cnosen le\e: of siiimncance. The - con- ritier.ee bantt for the mean or a rtouo - i- H'u.'.tinni was chosen in this , w,- to hew. ibe tile itatiiticai enor associated uh iueatii ilai.i ant! tii'- ter'''`"i<*t' '- t :i:',.. < T1BLE I Experimental Human Exposure to Vir.vi Chloride Clumorr Concentration ppm X S D. 11 ' ^51 ,-j 4'.* i -A. j Ransft* ppm - n3- ; i 213--*71 CCS-itj ppm Numncr oi iuo tects 243 4j-> 4*1* 4 -T - t .me^nzrueq a\erace concentration b&sea on 7,j '-.our: nciLiu.ni? 2 -.j-hour tunen period :n an 'jncorKammatea -'Cunctti.iO'js exposure :or 3,5 nours. Tabie I shows me anaivzed concentration to wnicia the iumects were exposed. Caiculattor.s c: the mean arm standard dc. mticr. ot exposure concentration are based or. mart raaair.trs irorn me ir.trarea soectrctmotcmster laxen at 5-m;r.ute intervals over me two 2.5nour exposure periods. Tire TWA is based on me totai 7.5 hours whim included a 2.5nour iur.cn period in an uncor.tnmmuied area. Tiie r.rtai breatii decay curves intended fc; use as an index to YC1 exposures were ad justed to TWA concentrations of 50. 250, so h Results /Tv' rnn, ntiil Breath Caret s A total of !o men particioaie-.i in me mice exueriinenrai citamber exnosu: at nominal concentrations of 50, 250. anti 200 run 'to- uueimj a total of 160 valid hi data voirm Five ot the six iumecis exposed :o 50 purr, were re-exposed at 500 open 2 davs later There was no inea;urai)'.,' r 'suhial >. iml cidoruie detected on the hi earns o; me mb'cis prior 'J tin* second exito-ine. renal breatn samniii'.o was initiated uumediateiv after the suhierts !ctt \"e rv'esutv chamner ana continued un to 20 horns lohuwuvj trie exposures. OOi 0 4 0 IQ 12 !* 6 UJ JO POST EXPOSURE nye.0URS Figure 5, Breath decay curves based on experi mental human exDosures to 50, J50, and 500 ppm ot VC! : 7 5-hour TWA). R&S160535 542 Xosember-Deccmber, 1969 wtrn confidence oancs ontv snqntiv wider than those from controlled human exneriments. The close simiiarirv between these curves and those constructed from controlled exposure data are farmer illustrated in Fiss ure 3. Human Responses Figure 6, three shifts. .'..`..*"=_ :....... a Variation :n VC1 Moor sxsosurs :cr and 500 ppm Figure 5 . A lOO-ppm decav From a suoiective standpoint no significant untoward affects were noted a: any of the exposure concentrations. The oniy comDiaints were those of two suoiects who renorted mild headache and some drvness of meir eves and nose burins me 550-npm exposure exneri- n^ ''arrT`r*x;v^y' .2''^', i ;iS?p - *`\`0C i:z *:r?5eri:'-`d ',\::h the C2'cu!^:ea '}zrc cor.- r.cer.ce bancs :c r the me an c: a 2*rr:p cf ob- ;er* a;;ons, 0n~:kc-]ob Breath Curse: T m worxmen taarttcmatea m me en-theob bream samaiintr program, orccaemz a :3Ui or 9! usable sets or data. Tor. percent of me breath samoies collected were discard ed aecause or pitm: leakace or ncor sampiini: ectmiques. Absolute nrearh le\els tanned from about 51 mm .n .one sarrmie taken less man : hour after an 3-hour TWA of 250 npm. to barely detectable levels <0.05 ppm in samples taken after exnn'tires at TWA's below 50 ppm. The extremes broad \ariaclon in tire T'A Vs experienced bv workmen durmu one ot ::.e periods m whicn breath samouni; teas beir.n conducted is demonstrated tor ttiree 'hiits of men bear inn tne job classification ''coaauiator operator" Fissure 6T Minute. hour;*1.*, *and daily h.uctuations in tile concen tration of a contaminant are most aescrmtivelv :eteaied by continuous monitonae. Fins method of samniina quickiv points out the .akuiv of hid" nj TW.\ and peak exposure concentrations >n the bads ot snot -amniina r melodic vein",; o: hue: du: af.on Tiie rematsanic correlation between breath concentration and con esnondinc TWA tal lies made it possible to construct the -eries of breath decav curses shown in Fi-twre 7. No odor was detected bv anvone enteiin? :i:e exposure chamoer a: 50 com. At 250 ppm ail tour subjects entering the chamber mittady reported mat mev couid detect a very siLqht odor cf the chemical. Five of the seven suoiects entering the exposure cham ber at cCO t:;ui w-ere cole to detect tiie odor of YCh but after 5 minutes of exposure those hve were unable to detect it even with forced inspiration. Three ot the four subjects re entering the chamoer alter lunch were able 3SEA1H v VL tlLCH'CE 1 ICNCENTPATIC^ ?u r 0= H". CD.NFfOENCE SAND ao; |j : 4 q a .o iz ,4 it ia 20 POST EXPOSURE riM,NQURS 1:u:ur 7. 3irat:i Jecav curves derived from brratn data collected from workers followine on* tUr-jon I'XDosures to VC! \ apor : 3-iiour TWA'. in go R &si60536 i American Industrial Hygiene Association journal to detect a faint odor c: YCh. One suoiec; coma detect a taint odor on ccep insmrztion for annroximareiy 15 minutes after entering tr.e exposure cr.amber. The exnosure had no noticeanie erfect on neuroiozicai responses. nor did it procacs sisnifiennt changes in the resuits of mer.cai. co rn dination. or manual cexteritv tests concoct ed tmiinz tne exposure period. Ah onmcai iaooratorv Lucies pertcrnieu in tne postennomre oerioa tvere normal anc no; sizmrii.ar.t.v dincier.t from pre-exposure '.a.ties. Discussion The object o; the en\ '.ror.menta. :tea;tn : is 'o identity the itmo-or.eric tontam.- r.ar.t. determine tne exttasur? _r.c re late t;us to the r.eaith r.azarc presents. I: or.e is to judge hazard bv amoier.t concen tration measurement;, men m.ose msasme- aors:- . nvl t-LCHI0E f" ' ::sc;stsr;CN. j- zzz:------------------------- * oi mer.ti mu-t accurate:', describe site exncsure on a tontmumz .nditicuai bas.s. A tiretm.v i : 3 :Z 6 3 SCST SiPCSt'RE TIME, -'CUPS ccr.auctec stirrev cotnmn.nz c: ntmuc.a an.ai- \\=;$ :: ;r.e 'act'; room cony oo v -.vid oro\'*.r. -a cata Ficcae 3. Cemoariion of breath cecav c:r-. ss aenveu item tne on-tr.e-'ob data ar.c :ae exacr:mrr.tai a urn an exposure cata. vaac for estirr.a,:me eTicnec ex no sure. mmtea ov tne nuinoer ot sampi.nz pieces C n riie othe: ::ana. oroa::-. col a*. j:.:a cs cons ; -acted :rcrr,: hrea;h do:a codL'jre a a a anc these probes are not amor, s cacao.e of e.ccurateiv measminz the indi\ idua.'s hah' ini: Tonciriuous 0 iont ror nnorir.z arc : a x.o<e exposure experiences, especially shouid tr.ese ,1`J! charcart -A nil I ob::oir,cc: ;rom >v,.oopiiri' vc:r'Nceri:: ients -a*:: :i Tdc5- 011 T'- c* :shOlI a; rhtTi'fore nc u^e:* n .1? a poccr.c a: c n - mvoi\e unusual .ncihences such as citemaca. spills or expo-lues omjirie the monitored area. oti :< -y 'xnosiifc :o \'C! arci liteam an.msis lias me ad\amaze ot ;n- [I..1:1 iTIOK'O C a : * c r;: e i one ot no*:: nitcn- r.n\ idua..nuts eatm worse:'; integrated dale.' :u;s illOlliU TC >cd do;L'tf"C,i oi: "TO \ adiai: 'xcosuie Breath tlecav ctu\es. as an index y, 1TC . si an ccs iki on ac L'- ..L-- oi -\cosme. oiler a means oi estimacint: tne aFoi cy.ziw.roio, cm TiCiid ;:: :: o'c: ::) ateiazc umiv mti:\ itiuai exnosure on the basn r.g "eak exposures arc mtumed ::'m. ..tn- oi a :e'a breach -amnies taken senahv m me dnuiHis mormcrinz. Concurrently. expo-mre oostexnosuie period. Consequents bream irenc; anti concent:aticr. zrachetus m.av help anaitsis can be used to diaznose as wed a- identity plant oociationa; merncicncies ant; quantitate an exposure which iias aireadt emimmem :na.functions ov :e-. eaiiiu meciric occtured. It is a relatively inexpensive arm sources of emission. i_ mTrctmz th.ese nro'o- simnie method which can be pm into opera 1 orris noc (: a :e^torc* c nen;:: :;u. en* tion uirnout extensise and costiv preliminary \ HOTmien: n it o;:on :o'u,os ia jomis -o\ it`duciiT: o'Vl'b TO.'A mate: :ai aoo. ttoti- ict. pieparations. Howeyer. pojtL'xpoiuie bteatii .mab-is does not punide infonu.uion on me daiiv iluciua- Continuous inomtorimr. houeNei. .1 e\- tions of exnosure. and die peak exnosure con u'ctr.eiv oosti\ bom in i.me ana in me .-quin- centrations are not made evident bv bream 1 men' ii'fii!"'1;!. Th.11 see^e of o.aia acme.::ed o data. Finailv, breath anaivsis i= not nnniica- R&S) 60537 bie to ail chemicais. and bream c.eca\ curses established lor one chemicai are not useiui as an index of exposure to anv other cr.em:cai. The dccav curves presented nere arc in tended to serve as an index of exposure to vinvi chioiide vacor and are based on an exposure duration of 7.5 hours for the experi mental exposures, and 3 hours lor me on-thejob studv. The close agreement between the two sets of curves and the narrow confidence bands obtained in each case demonstrate tits usefulness and accuracv of botr. metnods for estimating T'VA exposures ar.c indicate me unoortance of breath ana/.s.s arm me need for exoar.dir.z its use m evaluating ex posures to otr.er w-.ceiv used volatile organic chemicals. 5tew*rt. R D.. H. H. G*v D. 3. Erley. C. L. IWke, ana I . Psttrsov, Qber.auons on :r.c Concentration oi Tr.cr.ioroetnsiene m Elooc and E.xpireo Air loilov.- n? Exposure oi Huaians, .1 met. Ina, Aisoc, J 23 Asni 1762 Stlwart. R. D , ana K. Rowe: Qumze An* a'Ziucrs *ur *c 1 l.I-Trcnioroetnane. Arch. Sfatadu i F'nejj, 22 194-2C1 1 C**57 bt 3 D,. H C. Dhoo. E. D Baaettv. ana eFER inriii Exposure :o Scvrene Vapor. ___ 2 D Z D 3`RETTv. H. C, Do go and 7s, T-AesEljOS. E ,oer dentil Hasan txOo>ure CO Tetracn.oroef.nv icne .im. *ii iron. Heatn. rtG'A\RT R. D, :I, C. D^oo E. D 3*rzttk. a \\ vffer, ana J- Z. M'-TG:{c.er; Chronic Overexposure :o Benzene Vtoor. ?:ernteo at tne 3-xta Annual Meet* m :ne iccterv oi TGv.coio^v. Marcn 22-23, 1767 V.ama, Georgia Received Mav 25 iObo