Document dQmxb2Y2LKxRQ8gq7kDdVz00Q

Silk-3 -y/ l .SVpfemirr-Orfofcrr* J*/, -s section of this manual Shmulvakovskil, Ya. E.. ar.- --anskaya: Application of In:':... --DSfopy to th? Determination*: z Aromatic Hydrocarbons. -htroskeppii. Akad. .YaitI: fi. I. SR. 7: 367 H965!. a,.,., 7651h (19651. Ishida. K. z>( Mixtures of C0. Aroniat-r jaons by Infrared Spectroph... i.'jnko Kcnkyu 9: 27-40 I l%n r.str.57: 15B08g (1962). I I j 1 j j Infrared spcctrophotometr-. D., Y. Matsumoto. and K -naiysis of Mixtures of Oreari. -ds by the Method of Invert. _2) Spectrophotometry in il-i Kotu Taru. 14: 454 (1962 bstr. 61: 38a (1964). magnetic resonance. Takcurhi, .S. Yamazaki: The Precision e: "Titativc Analysis of Toluene arc! -rrzene Mixtures by High Rc*o!-.;. ! J.R, Spectroscopy. 67: 152' --hem. Abstr. 62: 83"3h (1965 r-ectrophotometrv. Kasimov. R. .. Aeacva. and O. 1. Dzhafarm: -.trftrnr>ir Annlvsis of DlCtlni- Dehydrogenation Product-Thim. 7.h. 1965: 101. Cher:. t; 18387b (1966U . I j \ j | I \ J j I mec of the ethylbenzene nitr.v.ie;: . adnitrocthylhcnzenc. Krivoru.i:- | Determination of Some Non-. | ' TUinces Which Occur in Pl.u::- | Styrcnc-Butadienc, Bund, am1 j r?nc Rubbers. Xozoc c Ob/</:* j . Analiza. (llabotv po Piotn - I*him.) 19G2: 101-12. Ch. 1816g (1963). j --ztcc of the reaction product mtroprussido in eoncenuat"acid. Dimitrov. D.. K. Fiat*'- unova. and M. Bratkova: Smne anions of Aromatic Compound* New Color Reaction of Muiui: _*side with Aiom.itic Cnm,*>ow: - ;k Kltim.AIi'khnol Jn-t. 9: ' I'hcm. Abslr. 02: lll53g ; 1 " J j ; Monitoring Exposures to Vinyl Chloride Vapor: Breath Analysis and Continuous Air Sampling EDWARD D. BARETTA.* RICHARD D. STEWART. M.D..* nd JOHN E. MITCHLERt Department cf F.nvironmtntal .1feriicine. Marquette School o{ Medicine. Milwaukee, M'iteontin, and Environmental Health Section. Bioehrmteel Rnrareh Laboratory, The Dow Chemical Company, Midland, hhehtgan An environmental survey was conducted to determine the time-weighted average exposure (TWA) of a croup of chcfinV.il plant workers to vinyl chloride (VC!) vaporT~Thls survey featured continuous multipoint air sampling and analysis using an infrared spectrophotometer. The inhalation exposute data were digitized and record ed on paper tape for subsequent computer analysis and derisation of daily TWA values for each worker. A breath sampling program was conducted concurrently with the environmental survey, and a series of breath decay curses relating post exposure breath concentration to vapor exposure were derived from the data. To validate the breath curves derived from on-the-job data, poucxpoiure breath curses were also constructed from breath data obtained following experimental huiran exposures to carefully controlled concentrations of VCl vapor. The close agreement between postexposure breath cone .-ntrations at the corresponding TWA's obtai ivd by each of the methods suggests that cither continuous air monitoring or bre.il> valid for estimating the worker's individual daily exposure to \ Cl* - ssef provide: .>.. n>lv<i< It a useful industrial iivciene lech.uquc for evaluating vapor exposure. Introduction he question that may arise Tfollowing an environmental survey is whether the chemical vapor concentrations measured ate truly representative of the ex posure being experienced bv the workmen. Evaluation of the ranges of atmospheric con centrations and estimates of time-weighted average concentration (TW.\1 arc all too often based on a few sj>ot samples obtained under conditions which are not reprosentati\c of all phases of a giwn operation. A more exact mcasmemen: of sapor i-\|k>miic would haw to he based on continuous moni toring of air in tlu* woikm.in's breathing zone during his entile work shift. 01niou-.lv this task is made dilliciill and often impossible 'tl-.i ... jirr-i-i.cil ji rS- ,\m. r u ,m I ii.iii.*. i.il ll-o--t lu.nlrrrmr. Si. M,........in. M.i\ II I:, l-.-l, * \f jr<|iirn# I.J M- limn-. M :I.H.W. I . lli-r.inxin. I I lie |li. ( ,1m imr.il (!.hii|*41U . Mnl>.i;*l. Mu Ju.'.in. by the large number and variety <-f tasks per formed by today's modern che nical plant worker. Recent improvements in automatic moni toring and data processing equipment have provided a means for a more satisfac'otv so lution. Sequential samplers and automatic analyzers and iccordi't's ran now be used to continuously monitor several locations or operations to provide more valid data on which to ha-e estimates of chemical exposure. Computer' can be utilized t*i manatru tin* hugs* ic'lunu- of data generated by continu ous mnnitoi iug.1 Meanuhile a technique has been under de velopment which more precisely deliues the level of individual esposute. The rrnh/.ilion that tlie total hotly burden of a volatile chem ical is directly related to its rnncentr.iti>m in expired air led to the dcwlnpimnt *t u-elinique;* for ctllecting and analwinu hieatli samples useful in estimating the more iruii- ">37 $2ri/f) c) - /i'Siz-Cipc /$(cH RSV 0012215 538 Noirmbtr-Dccruthn. /, vidualizcd cxjjosurc experience of each work* man. Studies bv Stewart ft al. s**! have shown that the excretion or "decay** of vapor in the breath can be used to characterize the c.\* posure. Drcath decay curves constructed for several chemical solvents have proved clin ically useful as an index to chemical expo sure. These breath decay curves, for the most part, were constructed from jtostexposme breatli data obtained from experimental hu man exposures to carefully controlled and relatively constant vapor concentrations. However, breath "decay curves have recentlybeen constructed from breath data collected from workers whose work environment was being continuously monitored.7 In this study of human exposure to vinyl chloride (VCI) vapor, breath decay curves constructed front data obtained during ex perimental exposures to the relatively uni form concentration within an exposure cham ber .vere compared with those derived at the theoretical!* equal, but. uioauiv fluctuating, coticentrannns enr*0'rp.,?rrd in a chemical plant atmosphere. A measure of the validity of continuous monitoring data and the use fulness of breath analysis in assessing timeweighted average exposure was reflected by a c'nse similarity between the two sets of breath decay curves. Procedures Monitoring the Plant Almosjilurt The cliemical installation survovrd closed structure housing several ,. chemical processing operations. Firu. .1 survey was conducted for each of four , classifications to determine the woik frequented by the workmen and thr titm- ti,. spent in each area. For each job rla^il'u.m. five sampling probes were strategic-ally >!.,, in tlie work area. A sixth probe was pl.i,.. outside tiie building, and charcoal ami di;... gel filters were placed in the sampling la. to assure a clean air reference. Tiie saniji'. probes were 5/i6*inch I.D. Saran tuhin- through which air samples were drawn In vacuum pump at a rate of 17.5 liietwuiii. to a centrally located infrared spcctropliomm eter. The spectrophotometer was equip;>i! witli a lO-mcter patli-length gas cell sm-i tive to 5 ppm of VCI at a wavelen- tli ; 10.63 microns. The VCI concentration w... lineariv related to absorbance up to .ip;>w. hnatcly 1000 pptn. A schematic diagram of the sampling '% tern is shown in Figure 1. Sampling wis w ecutcd sequentially with a set of six iw*>-u.o solenoid valves controlled by a timer whhn advanced the sampling location every ; min utes. A visual account of transmittance w.w recorded on a strip chart recorder. Mean while the data were recorded in digital fonn on paper tape by a tape punch and digiti/m* programmed to record three equally spaced transmitianccs during the last half of c;nh 5-iniiuitc sampling period. The iranMiiitumrc data fuiaidted by d;>spectrophotometct was convened to ab>od>ance and u-dua-d to concvnuation accoidin : to lJeer's law: CIP0SUA6 SUMMARY X>.time* weighted mean cxensuftc 001 !* Whir* Cj n*n to*rtt>iioa 1 S>a'*sn i r, * M' c*i>< l time lp*l II IMatian i >t clirity Piuvkk 1. Stliriii.viir di.tvr.im mC tlu* icJran-il rvutiiiMoiu, uuMiiwime *)*iein v. here A Vi A" A, j A= Log 10 (X.-X) (X.-X00) -- aloj bailee base-line iv'.|nuih\ " 1 espouse at total absorption. = response at location i. - 2. :j. -i. 5. <>. RSV 0012216 Tjubrr-Dfeftuber, Atmosphere Nation surveyed wa& .1 jBiig several srparaw :r?rations. First, a jo! j . for each of four jnh ratine the work an-j, jien and the time tiny : each job classification. rere strategically placed cseth probe was placed asd charcoal and silic.i _ in the sampling line reference. The samplr I.D. Saran tubing .:^les were drawn by .1 x`.o of 17.5 liters/min zrrared spcctrophotom-rmeter was equipped .-.length gas cell send. at a wavelength 01 'Cl concentration wa> rrbance up to approx- n of the samoline sv1. Sarm)lin<T urn i\. a set of six two-w.-n _rd by a timer which . .location every 5 min. of transmittance wa :_art recorder. Mean,-orded in digital fonu . punch and digithfi. three equally spaced ine last half of each ad. _ita furnhhed by tin* i'onvertrd to absorbr.centration according j i I X,"X") X;-XM) ; r-sjKmsf. _t total abruption. location i. 6, ' I J ! American Industrial Hygiene Association Journal 539 finally, C= KA where K C = a proportionality constant. ~ concentration The taped data were processed by a Bur roughs 5500 computer at The Dow Chcini<j] Company Computation Research Labora tory. The computer was used to calculate die mean and standard deviation of concen trations cat each location for each 8-hour work shift. Finally, time-weighted average concentrations were calculated for each job classification using the time-location data obtained from the job"5urveys. As described elsewhere,1 the weighted percentage of time dining which concentrations exceeded sev eral prechosen levels was also computed for use in establishing exposure profiles. Figure 2 describes the exposure profiles (frequency distributions) for the four job riassifirations studied during rhis survey. These profiles show the percentage nf time that C05JVS!!'.! ........... rxcrrjeu tin: levels MIOWli. lut) auiiunail is.v a u .d IZT.Z zl Minds of individually measured concentra tions and reduce them to single curves. Fig ure 3 shows the corrective trend brought about by actions undertaken to reduce tbc aimosjhcric concentration of VC1 over the 7-momh period during which the study was conducted. Only two job classifications war ranted extensive study, but men in all four classifications were asked to participate in the breath sampling program. FlGl'ftc 2. Exposure profiles expressed as VCI vapor ronccntraiioti \ersu> die exposure frequency distribution for the four job classifications. cap glass vial (Figure 4). The overall length of the pipet was about 9 inches, so it could be conveniently and inconspicuously trans ported lo and from work in a lunch bucket. The plastic caps were lined with six layers o.` Saran film identical to that used for the construction of Saran air sampling bags. A ?/32-inch hole predrilled through one of the caps hi ovkieti an access tor wiiiiuinvvtna sampL:. Ti.c Zzvzr. liner: provided ar. cl feettve gas barrier so that vapor losses were held to less than 10^c for a holding period cf 3 days. When collecting a sample the subject was rsked to remove the caps, place the pipci to his lips, and breathe normally in ilnough his nose and exhale through the pipet three (hi*tlu'*Job Hrratli Sampling 1 hrec separate hrratli sampling programs were conducted concuirentlv with the cu\iimnmntal plant survey, designated by the boxed portions in Finnic !. Each woiket collected three breath samples <!.1iIv--the first t*n his arrival home from work, the weenie! to 10 hours later, and a final sample be fore returning to woik the follow in'; dav The '``tuples were collected in pipvts roiMiurtcd horn shoi t lengths nJ L'O-inm soIt glass tubing 10 which had been welded at each end the threaded portion ni a 2-dram (fi-niri sciew- Khu hi. 1. Wi-fklv mean vapor cxju-suii* r.-nirn- tratinm mnM'trd iluriii' tin- urvrv. IVriuJi dur- inc mIuiIi Inr.ub vwu cxiidiii'ii'd are rrp- irsi nii'il by (In- bcxt-d-iii areas. RSV 0012217 *10 Kovembcr-DcccmWt, Figuki 4. Gl*i pipei (50 mi) used for collect ing breath samples. One rap hat a predrillcd hole for gas sampling. Both caps have Saran liners which seal the ptpet chamber. times. After expelling the fourth breath he quickly caps the tube, trapping a portion of alveolar air. The importance of writing the name, date, exact tunc of sampling, and the workshift most recently completed, on the label attached to each pipet. was stressed. Aliquots were drawn from the pipets with a 1-ml Hamilton gas-tight syringe and analyzcd in an Aerograph A-GOOli gas chromato graph using N2 carrier gas and a hydrogen flame detector. Separations were made with a 6-foot, Vi'mch I.D. stainless-steel column packt d with Carbowax 20M alkaline on Chromosnrh \V fi0/80 mesh acid-washed. --.Vp05U'>~ C/iu.-.vi > ^/yLiuiion Three experimental human exposures to VCI were conducted at nominal vapor con centrations of 50, 250, and 500 ppm. The exposjrc chamber was a room measuring 41 feet by 6 feet wide by 7.5 feet high. The room had a continuous positive air supply and exhaust system capable of maintaining a slight negative pressure within the cham ber. Continuous distribution of the cham ber air was achieved by recirculating the air with a squirrel cage fan through a series of inlet and outlet ducts spanning the length of the chamber. The YCI was metered into the duct carrying air exhausted bv the squirrel cage fan and entered the room atnuwphcrc via till' iTcirculation system at a tatc suflicicm to maintain the desired aimoqiheiic concen tration, The vapors were intindnred from a pressurized storage cylinder thioiigh fi feet of '/a-inch 1.1). stainless-steel tubing into a rotnincter prior to entering the em ulatin': air duet. A heating tape mapped around the stainlrss*Mrol tubing prevented condensation of the YCI and stabilized the flow of the vapor. Hie mmentialion of YCI in tin* rhamhet was constantly monitored with a Peikin-KI- mer infrared spectrophotometer equ:-,. with a 10-meter path-length gas cell. A v,. piing probe, consisting of 5/16-inch U). v, ran tubing, was centrally located duriu exposure to represent the breathing /on,. . all subjects within the chamber. The p>,.:. was moved about prior to each cx|imuie detect imbalance of vapor concrntr.t:!..-, within the chamber so that necessary rcctions in the recirculating system co,jj,| |. made. Air samples collected prjiodii.,:;. within the chamber throughout the vxi*^,,. day were analyzed by gas chromatograph* i.; added assurance of analytical accuracy, the infrared spectrophotometer and tin- v. chromatograph were calibrated before c.ni. experiment and at inier\-als throughout tir exposure day. Each 7.5-hour exposure day included j 0. 5-hour lunch period in an uncomami-utii! area outside the exposure chamber. Th.TWA concentration was calculated on tin basis oi /.5 hours ot exposure Clinical and Laboratory Procedures Each subject had been under careful medi cal surveillance by the medical dcpatiuinc for a number of years, and each teas given . complete medical examination a few d;n prior to the VC'I exposures. Included wena complete urinalysis and 24-hour mine l"i urobilinogen, complete blood count with rdimentation rate, reticulocyte count. SCO I'. SC5PT. LDH. alkaline phosphatase. IU'N. creatinine, and bilirubin. Mach subject received a repeat ph\Md examination J hour hcloie entering tbi* r\pOMite chamber. This exantinatiou imhiilid measurement of tcinpct .mire, blood .......... . and pube rale, n neurological cxuminaM ; and colli , lion of blood and breath sampl*A questionnaire noting the presence of am wniplun)' nf illness (for example, hcad-uk' nausea, thy iluoatl couipleted the pv.... v* posurc medieal evaluation. After the subject entered the cliamhi:. total expurd breath xamples were collected every bout by hav ing him hrenthr out t a Saran tube leading to a Saran phone k*: 1. vtion l*.iu ioealid nnohle tin- iIi.uiiImi I'id.d voimm* and total expir.ttntv c.tp.n it' RSV 0012218 ' :bcT-Decmbi'T, ;o-',9 ^ - notomtter equip]*-!] rcgth gas cell. A -eim..i 5,/16-inch l.D. S.iv located during ike sc breathing /one <<:' chamber. The pro)..- to each exposure l<> "apor coneenxr;iiif':N that necessary cor* -aring system could !>, ollectcd pcriodir.u'lv nughout the cxpr-unr --s chromatography for -.*tical accuracy. Both "ometer and the c.k Vibrated before cadi rrvals throughout the ` , 1 \ , 1 j ' \ *ure day included . an an uncomaminatvd :**ure chamber. The *aa calculated on the .rrposurc. sn under ca.eful medi: medical department . and each was given a ^znination a few dav :-?urcs. Included wen.and 24-hour urine for blood count with srd_iocyte count. SGO'l. - phosphatase. HUN. -D. rd a repeat physical tore entering the e\- exnniination intliutri! raturc, blood pri'-viu', rologieal rx.uniiutinu. d and brratli sainpJev r the presence of .my r example, head.idie. : ompletcd the pre-ex.Ion. -ntered the rhnmhri. -tuples were rnlleited :m breathe out throu-.M' *.t a Saran phi-tie et*lutsidc the ch.imbei. ' aI cxpiraiorv capacity ` American Industrial Hygiene Association Journal 541 were measured in the morning and again late in the afternoon exposure periods. Sitbjceth'e and neurtyiogical responses were measured before the subject entered the chamber. 15 minutes after entrance, and at l-honr intervals thereafter. Flannagan Co ordination and Crawford Manual Dexterity Tests were conducted at inidmorning and again in the afternoon. Breath sampling began immediately after the subject left the cxjjosure chamber. A 24-hour postvxposure m ine sample was collected and a blood sam ple was drawn the following morning for SCPT, LDH. alkaline, phosphatase. BUN, creatinine, and bilirubin determinations. Analysis of Breath Data The decay curves for the breath vinyl chlo ride concentrations were constructed by step wise multiple regression vising a digital com puter. An empirical relationship of the form Concentration = / (TWA, titnel was select ed from a choice of several terms, each based on TWA and/or time. The resulting regres sion equa.!.,.. Lwt reporter" "*' ordned re lationship between breath vinyl chloride con centration, time-weighted average exposures, and pcstcxposurc time. Eacl breath decay curve has an associated standard error of regression which can be used to compute the confidence band for any chosen level of significance. The 95^<- con fidence band for the mean of a group of ob servations was chosen in this case to describe the statistical error associated with the breath data and the regression technique. Tau I Experimental Human Exposure to Vinyl Chloride Chamber Concentration (ppm) 55 S.D. 59 SCI 491 4SU 2 8 7 3 Raofc (pp*"> 5- 53 5-2 518-471 525-473 TWA* (ppm) 48 248 4S<* 4S)J* Number ol Subjrcti 6 4 4 7 Time-ficHted average concentration bated An 7,3 hours including a 05-hour lunch period in au uncontaminsted area. tContintiOui exposure (or 3.5 hours. Table I shows the analyzed concentration to which the subjects were exposed. Calcu lations of the mean and standard deviation of exposure concentration are based on chart readings from the infrared spectrophotometer taken at 5-minute intervals over the two 33- hour exposure periods. The TWA is based on the total 7.5 hours which included a 0.5- hour lunch period in an uncontaminatid 3-mea. The final breath decay curves intended or use < a index to VrCi exposures were ad justed to TWA concentrations oi 250, Results 7:.v^rrmirm<r/ fiica/h Curves A total of 13 men participated in the three experimental chamber exposures at nominal concentrations of 50, 250. and Ti'jO ppm pro ducing a total of 160 valid breath data jioinis. Five of the six subjects exposed to 50 ppm weir jc-cxposcd at 500 ppm 2 days later. There was no measurable residual vinyl chloride detected on the breaths of the sub jects prior to the second exposure. Serial lucath sampling was initiated immediately after the subjects left the exposure chamber and continued up to 20 hours following the exposures. Fici'kv. 5. Un-aili decay rimes ti.is.-d .*n experinii'ju.d hj/m.ui i-.v/KKiire* io jn. Jin. ,wi<i 5<H> p[u of VC1 (7.5-l^.ir TWA). R$V 0012219 542 November-December, !%<> DAILY VARIATION IN EXPOSURE TO VCL VAPOR (8 hf,TWA) vn. Ci B*U with confidence bands only slightly wider than those , from controlled human expericnents. The close similarity between these curves and those constructed from contmlli-d exposure data are further illustrated in Fig. ure 8. Human Responses j* a .1 .* Oojr* ot w* Manth }- Fiochf. 6. Variation in VC1 vapor exposure for three shifts. and 500 ppm (Figure 5). A 100-ppm decay curve was interpolated from the available data using regression analysts. These curves are presented with the calculated 95 $e con fidence bands for the mean of a group of ob servations. On-lhe-Jol Breath Curves Ten workmen participated in the ou-tne- jnb breath. s*:r;;*!!..0 ptouucmg a total of 91 usable sets of data. Ton percent of the breath samples collected were discard ed because of pipet leakage or poor sampling techniques. Absolute breath levels ranged from about 20 ppm in inc sample taken less than 1 hour after an 8-hour TWA of 250 ppm. to barely detectable levels (<0.05 ppm? in samples taken after exposures at TW.Vs below 50 ppm. The extremely broad variation in the TW.Vs experienced bv workmen during one of the periods in which breath samplin'* was being conducted is demonstrated for three shifts of men bearing the job classification "coagulator operator*' (Finnic f>-. Minute, hourly, and daily llucUintions in the concen tration of a contaminant are nuwt descriptive ly revealed by continuous monitoring. This method of sampling quickly points out the fallacy of judging TWA ami peak exposure concentrations on the bads of spot vimpling or periodic surveys of briel duration. The tvmatkahlc eottvkuion between breath conremiation ami corresponding TWA val ues made it |H-.siblr to construct the series of breath decay curves shown in Figure ?. From a subjective standpoint no significant untoward affects were noted at any of tin- exposure concentrations. The only complaints were those of two subjects who reported mild headache and some dryness of their eyes and nose during the 500-ppm exposure experi ments. No odor was detected by anyone entering the exposure chamber at 50 ppm. At 250 ppm all four subjects entering the chamber initially reported that they could detect a very slight odor of the chemical. Five of the sever subjects entering the exposure cham ber at 500 ppm were able m detect the od<*. of YCi. hm ' ^ exposure those five were unable to detect it even with forretl inspiiation. Three of the four subjects re entering the chamber after lunch were able Ficrtti. 7. ltii-.tils tln-.iy cuivrs ilrrivril hunt Uu-.nli dat.i i.'IIi-inil itom wtulrr* fulli-wim: (tu--j.>!t i-\|i.iMnr* ). V(:| vs|><r 'U-hiMir TWA*. 1 . li It' n *t l.i c\ d; MU ] in.i ; i-u. <uu , ten | tun J 1*11 1I*T1 \i`h rum valu eSjM () | vonv j ing t ! agin tlutu dioul ml IV i T1, d> ' | riicm j I!V1. : "si I* liunxi tirmh ! idriiti.' *<1*11(11 MHtU IfllW I \ IM'IIM , by !) Ml. (V): lirm* : ini-nt i RSV 00X2220 -her, I96u -xly widei wcpcrl- u-een thrs,. controlled --ed in Fiy- n significant any of the " complaints ported mild -.--ir eyes and sure experi~rme enterin'; -ant. At 230 ihe chamber -Jd detect a - Five of the --osure cham- ,-Tfc? the odor with forced r subjects rr- lich were able 1,HOUftS "Nt-s di-rivcd h./ii .rrs fotlew io; .n* R*>nr TWA .. American Industrial Hygiene Association Journal 543 to detect a faint odor of VC1. One subject could detect a faint odor on deep inspiration for approximately 15 minutes after entering the exposure chamber. The exposure had no noticeable elTect on neurological responses, nor did it produce sig nificant changes in the results of mental, co ordination. or manual dexterity tests conduct ed during the c>qk>sure period. All clinical laboratory studies performed in the post- exposure period were normal and not signifi cantly different from pre-exposure values. Discussion ~ The object of the environmental health survey is to identify the atmospheric contam inant, determine the exposure level, and re late this to the health hazard it presents. If one is to judge hazard by ambient concen tration measurements, then those measure ments must accurately describe the exposure on a continuing individual basis. A carefully conducted survey combining continuous anal ysis of the nor#, iw.. atm^phere with a comprehensive job study will provide data valid for estimating time-weighted average exposure. On the oth *r hand, brcatli decay curves constructed front breath data collected dur ing continuous plant monitoring arc in close agreement with those obtained from exposure chamber experiments with YC1. These curves should therefore be useful as a second meth od for assessing exposure to VCt vapor. The choice of whether one or both meth ods should be used depends on prevailing circumstances ancl on the thoroughness de sired. For example, data useful in describ ing peak exposures are obtained from con tinuous monitoring. Concurrently. exposure ucnds and concentration gradients may help identify plant operational inclhciemies and equipment malluneiions hv rew.tliug specific sources of emission. Comrtintr these ptuhlems not onlv tr-toros a healthful wok en vironment but often results in bonu* savings hv leduciiu; losses <>l raw material and prod uct. Continuous monitorin'*, however, is extiemely costly both in lime and in the equip ment required. The seope of data at cpuied is Ftoear. 8. Comparison of breath decay curves Ui-aivcd !rcm bi? on-the-job data and the experi- SmiTT*" *vt*wure data. Knitted by the number of sampling probes, and these probes are not always capable of accurately measuring ihe individual's daily exposure experiences, especially should these involve unusual incidences such as chemical spills or exposures outside the monitored area. Breath analysis has the advantage of in dividualizing each worker's integrated daily exposure, llreath decay curves, as an index of exposure, offer a means of estimating the average daily individual exposure on the basis of a few breath samples taken serially in the jK'stexposuie period. Consequently bjvatlt analvri* can be used to diagnose as well as quantitate an exposure which has already occurred. It is a lelaiivcly inexpensive and simple method which can he pot into opera tion without extensive and cosily preliminary preparations. However, postexpnsme breath analysis does not provide information on the daily tint illa tions of exposure, and the peak cxpoMite vonceniraiiom are not made ev ident by in rath data. -Finally. Im-ath analysis is imi applica- RSV 0012^21 M4 Novembn-Dcccntbir, blc to all chemicals, and breath decay curves established for one chemiral are not useful as an index of cxjjosure to any other chem ical. The decay curves presented here are in tended to serve as an index of exposure to vinyl chloride vapor and arc based on an exposure duration of 7.5 hours for the experi mental exposures, and 8 hours for the on-thejob study. The close agreement between the two sets of curves and the narrow confidence bands obtained in each case demonstrate the usefulness and accuracy of both methods for estimating TWA exposures and indicate the importance of breath analysis and the need for expanding its use in evaluating ex posures to other widely used volatile organic chemicals. References 1. P*TON. J. r... H. It. Ilrtvu. xt C. J. SrutINI The Appliratiaa ( Computer Viewer to Iml.i.irul II, firne. Amtr. ltd. Hyf. .4m<k. J. 27: IfeNDCi W6>. 2. Sww*t. R. n.. H. If Civ, D. S. Ctur, C I,. m*. and A. \V. Scitoru: Munun xt>oturr Trn,<i....... rlltvleue Vj|iw: Krl.uinn^U|i of t'.ft)r*d Air am) I;'..., Coormiranom ii ttpukurc and Toxrriev. A'tk I.*. Hrmilh 2: Mb-S.*2 (Mae ITh.Ii, 3. Inwur. R. D.. It. It. Oav, D. S. E*u-.v. C. I.. I!,,, and J. E. I'lttjiaonOU'niiiam on the U.um-oii,. ... ( Trtrhloroeihvirne in Ufood and Evihrcd Air ,, in* V'xiMNiir v( Ituwani. .4mrr. lad. H\t- .for / i ItiMTU (April 4. Sir.tvtar, K. D.. and V. K. Row?.: Qmn>* d'bludn tur Ir 1.1,1-Trirhlnroelhane. A'<k. Mait.i,,. Pro/rM. 2: m-201 (ltx>;i. 5. SnwvtT, R, D., >1, C. Done, E. D. kumi. jn.i A. SV. Sen Ilf: Human Evpmurc to Suiciie Vji.u Artk. CiarM, Htaltk Id: No. i |M 6. Svt"ir. K. D.. E. D. Burro, It. C. I>m.. ...j T. R. To*krio*: Experiments! Human E\:</i>uir Telraehlorooilivtenc. AMA At<k. Eattraa. litallk (In prim), 7. uir. R_ D.. H. C- Dooo, E. I), Bturfri, A it ScHtrri*. and J. E. MvTcmra: Chrome Oterrvjh. to Utrinne Vapor. PrrwMicd ai Die Si\ih Annul y.r- in* of l>* Spotty of Toiieolepv, March 2J-23. Atlanta, Cti|it, Received Ma> ?fi. I *< Notices and Deadlines It is die policy of the A1HA Journal to accept and publish notices and short items of import and interest to our readers subject to the limitations of available space. This is done as a service to our profession and no fee is charged for such announcements. Some notices arc received too late to be carried to advantage in our Jour nal. Persons supplying announcements to us should keep in mind the time schedule of our publication. The Journal appears sx times per year with the copies being mailed about the 20th of February. April. June, August. October, and December. While emergency ur urgent notices can he inserted up to three or four weeks before the mailing date, such cannot be a*<uivd. Xoimally the announcements should be in the Editors hands at least two months or moir bcfoiv the issue in which they should appear. Perhaps these guidelines will aid you announcement generators. RSV 0012222