Document oeaDJpq6B6Qwd7Qx7VO54Q7dR

/Ifflp- --- -....... . --^ -? trr "7*0^1 *3>Iw"' C^'-Vl 194 s: RECEIVED Lctiers to the Editor fine o * M1 'VirENYLALiiSTNRHTDRrrCVl/.TION IN CULTURED FIBKOQLASTS friOM 1`ATl.HNTb WITH . J. j". BARR niEsyLXETO.suRiA Si*,---Estimation of (he activity of phenylalanine hydroxy* latt in cultured human fibroblasts would prrrr.it chariKtirrisa- tion of er.i'-rr.e defect* in variants of phenylketonuria (p-ax.).*'1 Furthermore, enzyme activity might alio be detect able in cultured human atnnioiic cells, yielding a prenatal ten > for r.x.i.% Differences in hydroxylation-ratc between normal^ individual* and patient* with pjt.t. should highlight Termcn in the expression of the gene coding for phony laluipi] hydroxylase in human fibroblasts. Vt e have found that 1: dauon of phenylalanine to tyrosine in fibroblastic u. from controls and patients with f.x.L'. i* ui fact differed/ diagnosis ofr.x.t. is based on clinical data only. Phenyl* levels in serum exceeded 20 ntp'dl, but further characi/risatton by loading tesla' has not been done.) Enzyme activity was tested in homogenate* oEffibeoWam t; cultured by standard methods. The reaction rputture (.Anal 1. foxat!0> or TYiosmt ntOM l-pHtm.tu.eis* k^raontss fiom kvhax maoauan or nolsul reasons axd or mtiisti clbucally MAGKOStD AS CLASSICAL r.f.l Group Naat dtluuiiuiien* Tyroditt tvmtd (pmaWtc$) / fMJPdlr PJi.V. ! A a c 0 1! Si IS / / ,/ sJ // ' J /' 45.0*4.5 S O X * M-M 7-0 * J-7 1 * 4? t *l 4-0 volume 0*15 ml) contained\jCbs 'following components: 0*1$ mg protein of homogenised fttoblasts. centrifuged at 45 OOOg for. V 30 min. *'tri" buffer pW7-44 7J matel/L magnesium chloride 3-0 mnwi/t, D.t,5,fi,7,k\elcahvdrobic7iertn dthydrochlotidc 19 judo1/1 (a gift from JDr VI. kapp and Or $. Skunca, Hoff* maita-La Roche, Onmzach-Vt'yhlcn), catalase 0-03 mg,N.A.D.H 0*49 sunol/1, yc-phenjrlalanine 0-3 ^Ct/wsay, speci fic activity 4S6/mCL''mrool <Amersham Buehler), l*C+,4C phenylalanine To ^trnoLI. Incubation was performed at 37C for 90 min. After chromatographic separation of ,4C*phcnylalanine frons Us.reaction products and liquid scintillation counting cdzyme activity was determined by the ainount of ,4C-tyroi/le formed. U thive compared the proteins of cultured fibroblasts of ten normal /individuals of unknown state of heterozygosity matched in sge and sea to four fibroblastic strains of patterns with ntx.tr. As can be seen from the table We observed a mean conversion of phenylalanine to tyrosine (given in pmol/Vmg fibroblastie protein' of 45-0 by normal individuals and 60 by patients withMcL*. Although three of the four patients oxidise a considerable amount of phenylalanine there n no overlapping in ctwymatK activity within the two groups- at least in the range up in the third standard deviation. This resell demonstrates in accord V: ance with the value* of the standard deviations obtained by testing fibroblastic strains of the same person for several times that F.K.c. can be diagnosed ui cultured human fibrublusit. Further studies will be pursued with incubation of the flbrcblam of these patients uuh teirahydropienns is Miluien And Kaufman4 observed a stimulation of enzyme activity in t Msi. IMin-mcM k'.,Ha.P Y Uva IHUm l M,,*.n.y.*-?c *j Cnrt, I. ItA*eu M. 1-. G. E.. lists. S. Anh On. CAHJfc IV?4. 4*. *1). 4. MikUiwL, Kaufawiw S. 1 SU. CW-, 197S.m, 4TT7. N.Ntv*WT.fc.;o 6' / OrtfnfbjWS THZ LANCET. JULY **J. IfTT liver slices by ihi^rocedure. Thus cultured human fibrobiasts will be on utrijent system for testing therapeutic possibilities for pauit$ vtfuh r jt.u. In all cultured fibroblast* Mycoplasma infection was excluded.* A dcuu&l descriptionof kinetic characteristics of the pheayl- ataniiKjnydroicyUsc tn normal tndividuait compared with pa- tier.t'sjwith f.k.u. is in preparation ,A'fthutik Prof. E. Moencti and Or H. Bartsch (L'revcnitlttkindrr& k, llfflirv', !>r 5.SchknkfrCUnivenuiiskmdefklirJt, Goetcintm;, Dr 0. Feist and hi* colleague* iUoivenitiisLinderk-lmik. rgl for the tkia espiuitts from patient* with r .x.t'., rj Ibvf. V. Hiy Dr VP. Nunsgm and their collaborators (Atlamcmn Knnkcahaus. Hamburji-Hiiburj) for the skin biopsies from normal indivi- duals. This work was supported by (he Deutsche Fonchuop- gecncintehaft (Sch 17J/2'. IIinmxhiirm.ntauir'OI luujinwt.i'piilnumiilitl.,ppreJorf, 2000 Hanburi 20, Fedeml Xcpatbe ofGcnttay R. W. HorriAtr* Oexlino Schxempf 1 VINYL CHLORIDE AND MORTALITY? Six,--Exceu cancer after exposure to vinyl chloride (v.c.) was demonstrated in animals by Viola aL* and Maltoni and Lefcmine* in Italy, and subsequently suggested by Monson et al.* and laterdefinitivelydemonstrated by several investigations in man in the United States.**'11 However, Duck cl aLu of British Petroleum in the U-K- found no excess of esnetr mor tality--indeed. the longer workers were exposed to vx., the healthier they seemed to be, as suggested by uble ll of their report, which shows a decreasing risk of death with an increas ing duration ofexposure. In those exposed for less than 10 yean, the nandardised mortality from all causes was 112, but it fell to 107 for those exposed between 10 and 14 year* and to 61 for those exposed for more then 15 years. Several interpretation* of thnr find ings are possible: (1) the formulated v.c. as received by B.P. i* uniquely non-ioxw, (2) vx. a* polymerised or processed at B.P. is uniquely *afe, (3) workers at 8.P. have a particular genetic endowment which decreases tbesr likelihood for vx.-mduecd eaneer, or conversely, other working populations1'* have a unique susceptibility to vx., or (4) certain dietary fac tors unique to the workers at S.P. may scavenge free-radical vx. (e.g,, some have advocated eating lots of onions or gariic containing free sulphydryl groups.11) Before venturing any interpretation in biological, occupational, or technological terms, however, s closer consideration ot ihe B.F. data seems true, especially in view of studies1411 which demonstrated that the s.M.a. for total mortality inereasci with sn increased duration of employment, due to elimination of the "healthy worker" effect. If in a follow-up study one selects, for example, a subgroup of workers by the fact that they bavr achieved at least 15 yean* exposure, then none of these worker* could have died before the Uth anniversary. *o ififormtuun on risk of dying can only come from the number of nun-ycars at risk and the number of deaths after 15 year*. Of counc these satns men, provided they are properly regrouped together with those dying or coming to the end of the follow-up between, for rum ple, 10 and 14 years can provide similar information for this time-(Ater*al--and *o on for U previous itmc-mttrvatv This t. XusxIL C,, NrexitM. C-, STillUmM< P. H. Njruw. 1VJ.2J1.4*1. 4. V>U. t>. L.. ttifOMi. A.. Caput*. A X,i 1**1, Jl, > 14 7. Matwm, C. Lcfcmine.C Atn.S Y AttJ.5a. l**J, 144,1 (J 5. Mmm, K. M'mn, J M., JeluiMO, M. K Lua.vc. 197*. u. It?. 4. *n,li| k J . Stnogr*. a ,rc*^ct, J. K, Jvnn, J.. S*iX. K. Caw, t: 4-, V Y A.M .fo 14*4.:?!.41). 10. NkWior. T, j., HtramMd. E, C. Sotow. K . SebkriT. I. L <>W. 14?]. a**. 11. T*trnh.1 I.CiAniV. X, J,n* Mtd. 1**4. It,SO* IZ. Uu.L.S ..Cnn, J. T.CrentevE. J. Untrt. I97S.U. 1147. |>. Siokupi.H E Nk Z.Ja MaJ l'4,*.?JJ AUM.IimL K j. Hi|MX S. C., Tfrtv. H. A J. *iy. MiW UTJ, JT, i;. is. D L.. Drnwmi, j, X'.jwwr. J. X., aincr. M. r. 4u M.Y. And. S*. 1**4. J*t,JZ4. I APddb06777 JaattiL 7 ( BWli ttemi THE LANCET* JULY 24, 1976 19$ uuiAivm or sat* v net tt at. sho-mxc iit -ii \t nivaiis vtasws tiTMttts m-Niiiit or urtcr:: Dtm: a*o *r BUATIONO* IXfOIlM WOCALStor DUTH IXirsuoaef etpuMK >*' C* Cause cfdeath Allaum \ E s-x. Ic fail carter. E j I.K.K- < 10-14 IJ- Duek Dusk a al b* f i! RF J Dv.tj Iwac'i A a! I RC ;a al RE *5 7*01 105-40 nr 7* ii) i 11-65 J* :i 121 It :* *1 44 *l-)0 :j-4v 7 0* i: *i r : 4 4!*il-:3l !* mi ! t W-*Jl.7j ?> 76 42S <10 l*H IJ lhpnti-v system anew > a *' SO* 10* 71 -10 1 MS 1 1*2 47 62 < 1 4 Ml 1 0 1 7 tsi tor; i - lime cancer 7 'siu-Ofc' US 3 * 2 2s. 101 4-tu c-s: *2 W 1)3 )4t tVatibierwd. Eahipenad. REuRakuUi6er.im*iM. ia tbc principle ofthe life-table method, which Duek al. teem ie have ignored. Their table ti putt the maa-years at risk for the 936 workers who had IS* yean duration of exposure at 6064. Our maxi mum estimate for this same category is only 4032. We aisumed that iU 336 workers began employment oa Jan. 1, 1948 (the first tlay of the study period) and had continuous employment vat3 Jan. I, 1975, and that the 25 deaths ia this group occurred on Jan. 1, 1975. thus estimating* minimum manyeats at risk. Since these workers belonged to the exposure group that completed 15+ years of employment, they would begin to accumulate man-years at nsk of dying on Jan. 1, 1963, so bv Jan. 1, 1975, the maximum estimate for man-yean t risk is 336 men x 12 years of observation (-4C32). Puck et al. would seem to have started accumulating man-years of observations for these workers immediately when employment began raths than after 15 yean of employment, thus diluting die estimate of the risk of death after 15 years of exposure. We have redistributed ih: man-yean at risk* shown in table tt of the original paper and recalculated the expected numbers of deaths, and the s-m.rj. These data are shown in the accom panying table, alongside those reported in the original paper. The 336 workers la the 15* yean exposure category had passed through the <10 and the 10-14 yean exposure cate gories ao we calculated the nun-years at risk for the 15* yean exposure category by subtracting 336x10 yean 10 year period) and 336x5 yean (10-14 yean period) from 6084 to give 1044. The 3360 and 1630 man-yean were then redistri buted to the <10 year and 10-14 year exposure eaiegories, re spectively, end the process was repeated for the 10-14 year exposure category, ini these excess yean were also redistri buted baek to the <10 year exposure category. VC e then calcu lated the ratio of our man-years to those reported by Duck et sU and applied these ratios to she expected death figures in tbeir report. For example, ia the 15* year exposure category, our estimate for total expected deaths ti: 1044/6084 (0-1716) X 41-30 (expected deaths reported by Duek et ai.) ** 7-09 (our expected). As shown in the table, there were (2$ deaths obierved/7-09) x 100*353 as our i-w.K. This is contrasted with an SJta. of 61, as reported by Duck et al. These same procedures were earned out for other causes of death Using ratios of 0-7615 and 1-4294 for the 10-14 yean and <10 yean duration of exposure categories, respectively. Since the exact distribution for worker exposure is unknown to us, we recognise that our estimates onJv approximate the numbers of man-yean at nsk. However, conditional to this approximation, and contrary to what was slated by Duck et al." ("there was M suggestion of an increased frequency of deaths from the most common RiJlignanl diseases"),* Jefmite pattern of raettist litMpKilie canter mortality associated with increasing duration ofv.c. exposure dearly emerges. As ti.swn in the table and as expected from previous reports,*18 u m the s.M.x.'s for total mortality and cancer deaths tend to increase srith aa increased durauen of occupa tional exposure. This example of imsalloeaiion of person-years at risk, the resultant erroneous conclusions, and subsequent reference to these ronclusions** '* demonstrate the need for 'lanoardssation of data-handling techniques tor cohort morta lity studies, as suggested during a workshop sponsored by the International Agency wr Research oa Cancer ia January, 1975, in Lyon, France.1* DiTition of Survcitl*M, Hazard Etaluauoits tnJ Kick! Slvtiio, Nainmal fattnuu for Occupational tilnvwi Health. Cinanfiau, Ohio 41303. U.S.A. J. K. W/tOOXER P. P. iKFAKTf EpaleaMtoff* and BiowaiiitKt Unh, (nicnuuunal A|cncyfr SntasSonCancw, lyon, Ima _ R. SARACCI V This Uttar haa been shown to the B.F. workers, whose reply follows.--Ed. L. Six,--Dr Joan Davis (personal communication) has also pointed out the value of aa additional tabulation of deaths more than fifteen yean after first exposure ia those exposed for at least fifteen yean, and this has been calculated. We have Just received these results (see table). The only major discre pancy between observed and expected deaths is in cancers of the digestive system. Two of these deaths were from stomach cancer and two from carcinoma of the colon. No firm conclu sions can be drawn from such a small amount of data* and only tbt passage of time will establish whether there is any real excess ofcancer mortality ia this group. MORTiurrroccmwo imi nmta vtaas* umsurx -- AH causes AUcanew Dkcnurviywai aw Ohacrml V 8 4 s exacted 84-12 J! t-l 2*4 10* 122 (2021 (tot) We would like to point out the methodological errors which led Wagoner et al. to their gross underestimates of expected deaths. An age-standardised death-rate can be calculated only if the age structure of the population ts known. The simplistic application of rates derived from a young population to one which is older--as a consequence of excluding tbc first fifteen yean of exposure-will produce a considerable underestimate of expected deaths and hence inflate any mortality ratios which are calculated in this manner. The number of rntn-ycan in the long-exposure group will also be in cxcen of the presumed figure, since exposure records started is 1948, but death-rates have been studied lor the period 1955-75. This design makes a life-table analysis for the whole study population impossible. We investigated mortality during the period 1955-75 for three groups of workers in which each individual was classified by his total duration of ciposure. Inevitably the low mortality throughout this period for the men with over fifteen years' exposure will reflect tbc long period of survival required to enter this group. A mortality study with a detailed cohort analysis cursing the whole U.K. polyvinyl chloride production industry is to be published shortly and the results will certainly be of in terest.1* ** OeeufuwasJ Health IMl, If. Rntofch Centra SMhtttWB-ThllOtl, MJJican B. W. Dice J.T. Carter . Jft.ttaiirr.l*. J .H'i.A.J *(, IV74.I.24). 17. liucmaiMaal Actacy far Hcwerch oa Conor, Ljw. Frtaec. Ut.U.C. war- aal uetaKal rrr*"i oa 71.001. Jammy, 1*71. l, k.tin, 1*. H,i V I'. Ai.l s<>. l*7a, at i, :i IV. Fua.A. J .Collier. P K tr.J. tmtMtJ. (til IW p,fw). 20. Fac,A.j..Coil>er,f-F.4r.y.^*.Mr.Mai/ laitesm), AP00006778 416 - v- u THE LANCET, ACGCST 2l*37i? lutncmixuviu <v "ittSfiysiJUMifU 0fKtxM>( HVSCL-l_U^JTCfKY with over 15 years1 exposure, * gives is the psper hr Dusk, etaL.iad it the reply by Duck AadCaner: .* ...^ /.-r/'j'riv *-v rK'-w -, .`iffwrt*.1 Oar^erum aftxptend ituA* giwtm ky Vu+i m it. 4*4 Dtui aU Cs***J*r iurtisi* ifixfann pxsur Um 13ytcrt Ssftcud *i:ki A* OiimW AHstiia '.$ . ' 2*2 22 ALssscsf 23*9 3-3 . 1 Tifirw M . 2*0 ' . * U{ tate A-1 9-2. 9 .,_. 'Vr.J*-:1.. \.v r AjfcaerDDuuec*kctiL' *&fiw*Dwkd.CMur *.. .'s'-.*,i SvThrppiarofthfccrfcidssfc!* tiat,t;.iiMiy.vi]idt scapar* .. ; expwd=outility. S.% -w.] )* UrutMtymL mf dJU.hyDixkMcL jy Jxnrie* g/ tXfm&t r*4 wwV UatH. . J5 * '* . ' DtirznoK ifrrpotur* -J^- r- etay'-'-i- io-u T , . > is-r' **.J- * ot e . Vj*.*. o e- ^-.sj*ju. k. * ^-Vv>-t:'^..s;>s^r4:.AiIcau^. , |j. |+.6- .u ;2L s*.( ., ju 25. 3*1. XJ3 ' . ' *':^WfcSi-iU:AlleMsa.. 21. 22.T. .,.J7 ,,i. >J J23^.____ : - ... . ema t ?-2. 13 t 1* JT * T-ff 220 '""* ;iMi.iMf ta ici-a ico v j.<- uj .2 3-0 im.. , v *: -..*.- -0:stterMi. E: especial. . t: s v .^.-- v: r _,JW":':Tbe SjurerfiK the Ism ihin 1J yerj,'expcstir*`c*tej3ri*f*`'; Virti?'..&*,ire-aCcountutsatisfECttry ikernativs-to the correct Spret." "`fwy2r'---UwHf;'.i ?'x -grou~p--<)LiboolSrbe. regariad.'a* front the ^gr*, which. Dock sad. Carter appear ' u-^L-4'5'Vi:-' fB.^^v ia presumed cafesrs unth- scrnal c.p.vl values. .Th* aphr ptr.rir.j '.sbttgvsi \ti sseiviJuAi Yjluss-of bsscpex^lc sur :o rjpply. KsweYsr, _tre a lhtls etidetee of ex^isf .ter:Jl:y, ci-'isr orirail sr era ssra. ST s.ji i, asr^t ieri ZyZ7 rscogtissi csrrien '5 as-*' easts havs^tely best u-itb iscrsisia; <2-nuot of expesurs. This is it csstrua to tbs . adic^alatf w-.ta uu.rcsd:s s: :feec-PJi- iitir.icn isvsrs* irsai jivsa by Du:k r. sb aai tho exasperated asti r!-tr. by :hs ovsrssrrestior. of ^'sjcrxr et *!. c.?.k. Jewsuaa xs a --s i.-i iizyi'j, >.:1; s~z zzjji'.im r..T. set cui by Ces att Lsa: ovs ZZ years a^o, u at exxreasly powerful asuiyticai.. U0h but it ....... .-..essoa witis all. nat5icaL:sd.,aid<giftTrtgrsL.TTffcinrffc.--. -- .. -. .Ws- . -. ^CrANSEI& * " '.^wr..-^^8afe >fe AP00006779 TV.I uyCIT Ji'JiCST 11,157b 417 scni:cemd ry vircu* ;;r.cn-' o3zcm:r3::i or. k; expawd far las. thin 1J year*, 3v calrulan-j expected deaths ;r.the Jei.n..:o:c ;:".c..-rr cappsur:--t.s., ir.a: --.stt wpciai for 3-: cveriaetcd 2 second, --.err subtle alas. Men. who because S CELLS^fzS5VS Sia,--VCe wish to rrplvjc Dr Mthuls'i's crv.iets--j July 3, p. 44` c: car zz~--~z..\ykz\:z piper by Cochran: :; si.3 Dr ViixaJsk; stai^That Cochrane e: si. id sc: showbill hspaiacyte*. rvev. ntr, Ccchr.mr :: il. tntn-eivrj that the Vayzi cytotoxicity after removing EAC- to be t cells.--"since it lupY^Ttnai the e5e-r.br years. Tha :* par. the =?!e* pmcess cf se'ecttca and sur* tisrj as CeVch-rates af it people enterinj 13 industry- tad these that rubs^ustly beecss un: irar-.ni it wars described '.Hi.* Mr Collier mb I`7 recognised these two weaknesses when * analysed the deaths for sbl nwn who had seen employed ia ENTRY *13 years 10-14 yni <10 ytars T?7~ 1C- *.4 years <13 ri*s j 10- w years 52 Exposure C2Fo!tow-up poried 3uc 0: si leasers- e: 1! - Fox a.ie Collier \t's stated that the cyteya^^y system was s antibody depesiatt, when perhaps^: should Save staled that their tyv however, sesms to hi<s interpreted cur statement too itrenj-y by attributes t-J'C* * eatejerrea! exclusion of the ashbeby^ depend:.-.: nature of ::1L -- eciutei eytetesietty. He presumiiy' meant thisydcurrrr: reference to our cnnt-ent ;s apph^duiy exiitenei 0: anuscdy-cepeniinvceliulir cytotsxtc^y,'a.s.3.c.) in SHa!. A.3.C.C. -IV be mediated by mere than jt* cell, but renter then stress `.he pcttible hater*jsnehy^^Dr M-.kuisk: dees, we it is currently underttood arctj^prsssnue of ar.ttooby ;n the tor torFc IjG or. the efidior cells. K. cell designation ter the elector rsiJi would be-xfiore universally acceptable had Fc lyG sen: 5^rvrs/^Li c:0: is ncV considered to he titi hiil- FJtvUfk Te^ITwith Dr Mihulthi :ha: the pipsr i/ i*' 1 I- , u.has XCCS-gP, :'A.Ji.Fct . .- , " K. idT-rs Gaums* . .. . . . QF7rj.T-acf *siM*Cu*c. rSv ... _______________ ;' '' ' ''. cn>ffaa Geata) Hespo stead fa.guy afTeresas. ........................ ... J ". Tanas*. 3n|ne, CifiW ... e. J_03itr.?.'F.flV;7. ii'iWinrissi*oreuJ. " ' .'' '*U^ll----l-..'' ...i.-- >' -- ' ' ', ^/j. 3. wAUEH. i-~:." ............. ?. Few A. CsJ'tr. P. F. gr.J. 'ia.^a-yns}. . ..... . .* a.et^tfcbaei.AiJ^tapie*.tOy-Tyniffi.a;*j.a*w*i..Hi a7jtj7p,T;:.'`'t.stc*f,.a;fC'Ofrpri.r;V-ti.-t*?vi,7M. - V - ' T-Ogte. f. 1uyylm.au La itskssusBiLKsyarrofe=aRegym GeacraCtliv : V -.U AP00006780 Mutation Research, 41-(1976)131--142 EUevir/North'Holland Biomedical Preaa CARCINOGENIC, MUTAGENIC AND TERATOGENIC RISKS ASSOCIATED WITH VINYL CHLORIDE PETER F. INFANTE, JOSEPH K. WAGONER and RICHARD J. WAXWEILER Division ofSurveillance, Hazard Evaluations and Field Studies, National Institute for Occupational Safety and Health. Main Pott Office Building, Cincinnati, Ohio 45202 (U.S.A.) (Received May 13th, 1976) Summary The data presented demonstrate clearly that vinyl chloride (VC) is related to a significant excess of mortality from cancer of the liver, lung and brain among workers occupationally exposed to VC. The risk of dying from cancer of the lymphatic and hematopoietic system also appears to increase with an increase in latency. These cancer sites could have been predicted by the animal bioassay conducted by Maltoni. With regard to the liver, even the histopathologic type of cancer (angiosarcoma) was observed first in experimental animals. A study of cancer mortality among populations residing proximate to VC polymeriza tion facilities also demonstrated an increased risk of dying from CNS and lymphatic cancer. These latter findings raise cause for concern about out-plant emissions of VC, but without further study these cancers obviously cannot be interpreted as being related to out-plant exposure to VC. Various test systems now have elicited a positive mutagenic response to VC. Thus, our observations of a significant excess of fetal mortality among the wives-.of males, who were occupationally exposed to VC, raise public health concern that VC may be mutagenic in humas. With regard to the teratogenicity of VC, observations of a significant excess of children bom with birth defects were reported among populations residing proximate to VC polymerization facilities. Additional epidemiologic study is needed to determine whether a repeated pattern of excessive numbers of children bom with birth defects can be observed in other communities with VC polymerization facilities. Introduction In 1930, tiie first adverse health effects of vinyl chloride (VC) were reported [221. Since then, numerous investigators have reported the toxic effects of VC on the central nervous system, the liver, the bones of the fingers and the lungs 132 [2,5,9--12,18,20,28]. More recently, the study of VC toxicity has broadened to assess the spectrum of carcinogenesis [2,15,16,21,26,29,30], mutagenesis [1,3,4,6,13,14,23,24]. and teratogenesis [8]. These efforts were stimulated by the work of Viola et al. [29] who, in 1971, reported the induction of tumors of the skin, lungs and bones in rats exposed by inhalation to 30,000 ppm of VC over a period of twelve months. Widespread concern for the carcinogenic activity of VC, however, did not occur until early 1974, when Creech and Johnson [2] reported four deaths from angiosarcoma of the liver among workers employed in the manufacture of polyvinyl chloride (PVC) resins. It was later learned that Maltoni had previously demonstrated VC-in duced hepatic angiosarcomas, lung adenomas, brain neuroblastomas, lymphomas and various other tumors in mice, rats and hamsters [15,16]. With regard to mutagenicity, several Investigators have induced mutations via microbial test systems [1,14,24]. Also, VC metabolites have induced mutations in mammalian cells [6]. In addition, reports from several countries have demonstrated significant excesses of chromosomal aberrations among workers exposed to VC as contrasted with those not exposed [3,4,13,231. Because of these observations and of the widespread exposure to VC among both workers and the general population, the National Institute for Occupational Safety and Health (NIOSH) in the U.S.A. undertook an epidemiologic program to evaluate the magnitude and spectrum of VC toxicity to humans. This program was 4-fold in nature and sought to evaluate: (1) The site-specific risk of cancer among workers exposed to VC [30]. (2) The risk of some cancers among populations residing proximate to VC polymerisation facilities [8], (3) The site specific risk of congenital anomalies among populations residing proximate to VC polymerization facilities [3]. (4) The risk of fetal wastage among the wives of workers occupationally exposed to VC [7], Cancer risk among workers exposed to VC To assess the neoplastic risk of workers exposed to VC, a population con sisting of employes from four VC polymerizing facilitates was selected for cohort mortality study [30]. Since occupationally induced cancers often take many years to become manifest, the study cohort was restricted to workers who had achieved five or more years of employment and for whom at least 10 years had lapsed since initial employment. Thus, the exposure period was five or more years and the latency period was 10 or more years. Follow-up for study cohort members was greater than 99%. Table I shows the total mortality experience among the study cohort. The expected numbers are based on United States mortality data applied to NIOSH's modified life-table method. For alt malignant neoplasms, there were 35 observed vs 23.5 expected, the SMR was 149. This excess was significant at the P< 0.05 level of confidence. For total mortality, 136 deaths were observed vs 126.3 expected. Selecting a cohort with at least five years work experience and 10 years latency eliminated the "healthy worker effect" [19] and so there were more total deaths than expected and this was mostly at the expense of cancer mortality. Table II shows cancer mortality experience by greater than 10 and 15 year latency periods. At the greater than 10 year latency period, only biliary and I----------- ------------------------ -------------------------------------------in--------- AP00006782 133 TABLE 1 MORTALITY EXPERIENCE AMONG COHORT WORKERS EXPOSED TO VINYL CHLORIDE CauM of death ICD eode * Observed Bxpeeted SMR b AU malignant nroplaims Heart Non-malignant respiratory diaaaaaa Cirrhotic All ether causes (140-205) (400-443) (470--597) (581) 35 57 2 36 33.5 S4.7 3.4 4.0 40.7 140 e 104 176 50 8S * ICD, International Classification of Diseases, 7th revision, b SMR, standardised mortality ratio. e Significant at P < O.OS. liver cancer deaths were significantly in excess; however* when the sub-cohort with 15 years of latency since initial employment was used, deaths from three categories of cancer were significantly in excess. The excess in mortality from cancer of the lymphatic and hematopoietic systems was not significant; however, the SMR increased from 159 to 176 with an increase in latency. These comparisons show the importance of latency when looking for occupationally-induced cancers. table u CANCER MORTALITY BY INTERVAL SINCE INITIAL EXPOSURE AMONG WORKERS EXPOSED TO VINYL CHLORIDE Site of malignancy 10* years 15* years AU malignant neoplasms Brain and CNS cancer Respiratory system cancer Biliary and liver cancer Lymphatie and hematopoietic system cancer All other malignant neoplasms Obs.* Exp. b SMR c Obs. Exp. SMR Obs. Exp. SMR Obs. Exp. SMR Obs. Exp. SMR Obs. Exp. SMR 35 23.5 149 4 3 0.9 329 12 7.7 156 7 0.6 1155 e 4 2.S 159 9 11.7 77 31 16.9 < 184 c 3 0.6 < 498 d 11 5.7 < 194 d 7 0.4 < 1606 * 3 1.7 < 176 7 6.4 < 83 1 Obs.. observed. b Exp., expected. e SMR, standardized mortality ratio, d Significant at /' < 0.05. c Significant at!' <0.01. 134 - In laboratory studies, Maitoni has induced hepatic angiosarcomas, lung adenomas, brain neuroblastomas and lymphomas [16]. Therefore, the predictive value of animal bioassay studies can be demonstrated, not only by the observation of a significant excess of angiosarcoma of the liver among VC workers, but also by significant excesses of lung and brain tumors. Cancer risks in populations residing near VC polymerization facilities The risk of some cancers among adult populations residing in the only three Ohio communities with VC polymerization facilities was assessed [8]. All three communities had at least one facility in operation by 1954 and Painesville had a second plant in operation by 1967. The community population sizes varied from 12,000--24,000. Between 1960--70 the population had remained stable in Painesville and Ashtabula, but had increased by 30% in Avon Lake. As reported previously, for the three communities taken as a whole, there were no apparent differences in racial origin or family income as compared to the aver age for the State [8]. As a result of previous findings [26], cancers of the central nervous system, lymphatic and hematopoietic systems, were selected for study. Because of possible error in death certificate data in terms of metastases from other primary sites, data for lung and liver cancers were not analyzed. Table III shows data for observed versus expected CMS cancer deaths in the white population by sex for the period 1958--73. North Ridgeville is the only community shown which does not have a PVC polymerization facility. It was included in the analyses of the cancer data because it is located contiguous to Avon Lake and because it had a high incidence of children bom with birth defects (8). If North Ridgeville had not been included in the analyses of cancer mortality, little difference in the results would have been observed. Expected values are based on the occurrence in the balance of the counties over the same period of time. As shown in Table III, there was a significant excess of CNS cancer deaths in males. The excess was greatest in Painesville and North Ridgeville. With all communities combined, there were 27 CNS cancer deaths observed in males versus 14.1 expected; the SMR was 191. The difference was significant at P< 0.01. In females, with all groups combined, there was only a slight excess. With sex groups combined, the excess was significant at P< 0.01. It may be note worthy that one father-daughter combination for CNS tumor deaths occurred in Painesville. The daughter died of a papillary ependymoma in 1963 at the age of 16. The father died two years later of a glioblastoma multiforme at the age of 58. It would be difficult to determine whether this observation is the result of genetic or environmental factors. Table III also shows deaths from lymphomas. Although the differences between observed and expected deaths in males were not significant, there was a consistent excess in each community. In females, there were excess lymphoma deaths in two of the four communities. With sex groups combined, a significant excess of lymphoma deaths was observed in Ashtabula. With sex gToups and communities combined, the number of observed deaths was 61 versus 48.7 expected. The SMR was 125. This was significant at 135 TABLE It! OBSERVES AND EXPECTED DEATHS FOR THREE TYPES OF CANCER FOR RESIDENTS 46 YEARS AND OLDER IN THE OHIO COMMUNITIES WITH VINYL CHLORIDE POLYMERIZATION FACILITIES, 1968--13 Expected numbers of cancer deaths based on occurrence over the same period of time in the balance of the counties In which the communities are located. Males Females Sexes combined Athlabub Painesville Avon Lak* N. Rldaevltte Communities Combined Obs./Exp. SMR CNS cancer (191 -192)* 1/ 6.1 12/ 3.B it 2.3 6/ 1.9 1)6 3l6d 87 316 b 27/14.1 191 c Obs./Exp. 6/ 3.8 2/ 2.8 1/ 1.8 2/ 1.5 11/ B.9 SMR 168 71 56 133 111 Obi./Exp. SMR 13/ 9.9 14/ 6.6 3/ 4.1 8/ 3.4 38/24.0 131 212 b 73 236 b 158 c Athlabub Painesville Avon Lake N. Ridxevilb' Communities Combined Leukemia and aleukemia (204--207) * 13/14.7 8/ 7.1 1/ 3.6 2/ 3.2 08 113 28 63 11/ 0.6 7/ 6.8 5/ 2.2 0/ 1.9 24/23.6 84 23/19.5 128 103 227 0 118 24/23.3 15/13.9 6/ 5.8 2/ 5.1 47/48.1 103 108 103 39 96 Ashtabula PainesvilJe Avon Lake N. FUdxwm* Communities Combined Lymphoma* (200--203)* 18/12.6 12/10.4 4/ 3.3 3/ 2.8 143 115 121 107 .17/29.1 127 14/ 5.8 4/ 8.3 5/ 2.9 1/ 2.6 24/19.6 241 * 48 172 38 122 32/18.4 16/18.7 9/ 6.2 41 5.4 61/46.7 174 c 86 145 7t 125 * International Classification of Diseases. 0th revision codes. b r < i>.05, c r < o.oi. d /' < 0.002. 0.05 < P < 0.10. Data were then analyzed for leukemia and aleukemia mortali ty. As shown in Table III, the observed versus expected mortality was virtually identical. Birth defects among populations residing near VC polymerization facilities The occurrence of birth defects was studied [8] for the same three Ohio communities with VC polymerization facilities. Birth data for residents of North Ridgeville were not combined with data for the three index communities in (he initial analyses (Table IV) because the high incidence of birth defects in North Ridgeville, which lies contiguous to Avon Lake, was identified in subsequent analyses [8). Data for North Ridgeville, however, were included in subsequent analyses (Table V) for specific birth malformations. The observa tions among community residents were compared to both the occurrence in AP00006785 136 TABLE: IV RESIDENT BIRTHS. MALFORMATION RATE PER 1000 LIVE BIRTHS IN OHIO AND IN THREE SELECTED COMMUNITIES AND OBSERVED VERSUS EXPECTED NUMBERS OP MALFORMA TIONS IN EACH CITY. YEARS COMBINED. 1970-73 Malformation* ar* bated on code* 740--ISO of the International Classification of Diseases. 6th revision, 1988. Arts Entire state of Ohio Ashtabula city PainesviUe city Avon Lake eity AU three communities combined Malformation* Births Rate/109 719.287 1900 1381 738 4019 10.1 17.4 18.1 20.3 18.2 Number observed 7295 33 25 13 73 Number expected * _ 19.3 14.0 7.5 40.8 xa _ 9.78 b 10.29 b 7.56 b 27.13 e * Expected number* are bated on state rate per 1000 Uvc births. bF<0.01. e P <0.001. the balance of the counties in which the communities are located and to the occurrence in the State for the period 1970--73. Between 1970--73, the rate for birth defects changed from 9.3 to 11.3 per 1000 live births for the balance of the counties, from 9.6 to 10.8 for the entire state, whereas, the rate for the three index cities combined changed from 17.0 to 22.5. Thus, the incidence of birth defects for children bom in the index cities was almost twice as great as the incidence in the balance of the counties or in the entire State, and the differences appear to be increasing with time. Table IV shows data for malformation rates in each index community versus the rate for the entire State. These differences were all highly significant. The rates ranged from 17.47 in Ashtabula to 20.33 in Avon Lake, as compared to 10.14 for the entire State. When the community experience was compared to the occurrence in the balance of the counties in which the communities were TABLE V OBSERVED. EXPECTED AND RELATIVE RISK FOR SPECIFIC CONGENITAL ANOMALIES IN INDEX AREAS INCLUDING N. RIDGEVILLE, 1970--73 Defect category Number of defects RR b Observed Expected AU defect* (740--756. 768. 759) c Centra] nervous system (740--749) Cleft palate and lip (749) Genital organs (752) Clubfoot (754) All other defect* 109 17 * 10 16 23 48 56.0 5.6 6.5 6.4 6.2 27.2 1.96 3.02 1.53 1.90 2.79 1.58 " Exclude* skin, heir and nail* (767). b RR. relative risk (observed/expected). c International Clasiifieatlon of Disease code*. 8th revision, are shown in paranthese*. AP00006786 137 located, the differences remained significant. Therefore, whether you compare the occurrence in the communities to the expected, based on the average for the State, or for the balance of the counties, the excess of children with congenital anomalies in the communities appears to be significant. Table V shows observed versus expected numbers and the relative risk for total and selected malformations. Although an increase in most organ systems was observed, the greatest excess of severe defects included malformations of the CNS, deft lip and palate, club foot and genital organs. These observations have been reported previously in more detail (8]. Fetal mortality among wives of workers exposed to VC Since VC had elicited a positive mutagenic response via microbial test systems [1,6,14,24] and also had been associated with significant excesses of chromosomal aberrations in the lymphocytes of workers occupationally exposed to VC [3,4,13,23), concern was expressed that VC may induce germinal mutations. Thus, a questionnaire-interview survey was conducted to ascertain the incidence of fetal loss (defined as any product of conception not born alive) among wives of workers exposed to VC [7aJ. All current VC polymerization and polyvinyl chloride (PVC) fabrication workers were included for study together with a similar number of current rubber workers selected from work areas relatively free from known toxic materials and matched as a group to the VC workers by age. No interviews were conducted with workers' wives and no data were obtained concerning maternal age, except indirectly through paternal age. Group participation rates ranged from 62--77 percent. Data for the wives of VC polymerization workers (study group) were contrasted with data for the wives of PVC fabrication and rubber workers ("controls"), who were known to have had very low or no VC exposure, respectively. The data in Table VI show the paternal age distribution for fetal deaths according to the husband's exposure. Prior to husband's exposure, the crude fetal death rates for the control and study group were 6.9 and 10.1%, respectively. Subsequent to husband's exposure, the crude rates were 8.8 and 16.5%, respectively. As can be seen in Table VI, the excess in fetal mortality subsequent to husband's exposure, was associated with younger-aged husbands. For husbands 30 years of age and older, the rates for the control group 17/142 (12,0%) and primary VC exposure group.9/69 (13%) were about the same; whereas, for husbands less than 30 years of age, the rates for the control group 7/131 (5.3%) and primary VC exposure group 14/70 (20.0%) were significantly different, P< 0.001, x* " 10.52, with one degree of freedom (df). The excess of fetal mortality among wives of younger-aged husbands may be a reflection of a practice of placing newly hired personnel because of little or no seniority, in jobs where occupational exposures to VC may have been worse. This hypo thesis, however, needs further assessment in other working populations. Since parental age was positively correlated with fetal mortality in this population and in a previous study [25], fetal mortality rates for the study group were adjusted to the age-distribution of the control group. AP00006787 138 TABLE VI PATERNAL AGE DISTRIBUTION FOR FETAL DEATHS ACCORDING TO HUSBAND'S VC EXPO SURE Patarna) age group (years) "Controls'' Primary VC Exposure Pregnancies Fetal deaths pregnancies Fetal deaths <20 20-24 25-29 30-34 >35 All ages crude rate Mean paternal age al conception (year) Age-adjusted * rale (N) (N) <*> Prior to husband's exposure 31 80 38 6 4 159 23.0 2 6.5 4 5.0 4 10.5 1 16.7 0 0,0 11 6.9 (6.9) (N) 7 44 66 27 14 148 26.4 (N> (r.) 0 0.0 2 4.6 7 12.6 5 18.5 1 7.1 16 10.1 <6.11 >20 20-24 25-29 30-34 35 AH ages crude rate Mean paternal age at conception (year) Age- adjusted * rate Subsequent to husband's exposure 1 43 87 87 55 273 30.4 0 0.0 4 9.3 a 3.4 7 8.0 10 18.2 24 8.8 (8.8) 0 22 48 36 33 139 30.2 0 0.0 3 13.6 11 22.9 3 8.3 6 18.2 23 10.5 (15.8) * Petal mortality rates for primary VC exposure group are direct aie-adjusled to the paternal age-dittribulion of the pregnancies in the control group <thouin in oanntheaesl. TABLE VII mean paternal, number of pregnancies and aoe-adjusted fetal death rates ACCORDING TO HUSBAND'S VC EXPOSURE "Controls" * Primary VC exposure ** Number of families Mean paternal ape at conception (yean) Number of fetal death* among wives Number of pregnancies Age-adjusted fetal deaths/100 preg. e Number of families Mean paternal age at conception (years) Number of fetal death* among wives Number of pregnancies Age-adjusted fetal detths/100 preg. c Prior to husband's exposure 99 23.0 II 1 SB 6.9 70 26.4 15 148 6.1 Subsequent to husband's exposure 113 69 30.4 30.2 24 23 273 8.3 139 15.8d * Rubber and PVC fabrication workers, b VC polymerisation workers. c Rates age-adjusted to "control" group paternal age distribution. d Subsequent to husbands' exposure, the frequency of fetal deaths among wives was signifieentlv greater in the primary VC exposure group as compared to the "controls" (P < 0.05) or to the frequency in the study group prior to husband's exposure (P < 0.02) by ago-adjusted Chi-square testing. 139 The data in Table VII show fetal death rates per 100 pregnancies for the wives of male workers in the control and study groups. Prior to their husband's exposures, the rates were 6.9% and 6.1% for the control and study groups, respectively. Subsequent to husband's exposure, however, the rates were 8.8% for the control group versus 15.8% for the study group. This difference was significant at the P < 0.05 level by Mantel-Haens2el Chi-square testing 117] (xJ" 4.84, df- 1). Further, the before and after exposure comparisons indicated changes in rates from 6.9 to 8.8% for the control group as compared to a change from 6.1 to 15.8% for the study group. The rates for before and after husband's exposure in the study group were significantly different (P< 0.025, Xs - 5.78, df * 1). For the study group, it may be noted that before exposure age-adjustment reduced the crude rate from 10.1 to 6.1%; whereas, after exposure the crude rate was reduced from 16.5 to 15.8%. The greater reduction in rates for the before exposure age-adjustment resulted from a difference in the age distribution of the husbands in the two groups. As can be seen in Table VII, prior to husband's exposure, the mean paternal age in the study group was 26.4 years as compared to only 23.0 years for the control group, whereas, subsequent to husband's exposure, the mean ages of the two groups were virtually the same, i.e., 30.4 years versus 30.2 years. In both situations mean age was a good measure of central tendency. To determine whether women who had chronically experienced abortions might have weighted the results in favor of a higher fetal mortality rate in the primary VC exposure group, data for the pregnancies of women who had two, three or four or more spontaneous abortions were eliminated. The data were then recalculated to determine whether or not the trend of a greater mis carriage rate could be maintained. As shown in Table VIII, the trend was maintained for each analysis. TABLE VII! NUMBER OF PREGNANCIES AND AGE-ADJUSTED FETAL DEATH RATES ACCORDING TO HUS BAND'S VC EXPOSURE EXCLUDING PREGNANCIES IN WOMEN WITH >2. 3 OR 4 FETAL DEATHS Rates lor the primary VC exposure group ara age-adjusted to tha Control group Controls Primary VC exposure Number of pregnancies Fetal death rate Number of pregnancies Fetal death rate Before husband'! exposure Alter husband's exposure >2 Fetal deeithi excluded 155 255 5.8% 4.7% 126 111 1.7% 6.2% Before husband'sexposure After husband's exposure >3 Feta] deaths excluded 159 265 6.8% 6.8% 141 120 3.1% 10.8% Before husband's exposure After husband's exposure ^4 Fetal deaths excluded 159 265 6.9% 6.8% 142 127 5.8% 11.6% AP00006789 140 As reported previously [7b], additional analyses suggested that the significant excess in fetal mortality after the husband's exposure would not seem to be the result of bias from interviewers nor from respondents. Because of the highly volatile nature of vinyl chloride [271, carry-home exposure to the wife would seem unlikely. Therefore, the leading possibility for the mechanism involved would seem to be germ-cell damage in the male through direct VC exposure. References c.1 Birtcch, H., Malavielle and R. Montesano. Human, rat and mouse liver-mediated mutagenicity of vinyl chloride in typhlmurlutn train*, tnt. J. Cancer, IS (1975) 499--437. 3Creech, J.L.. Jr. and M.N. Johnson, Angiosarcoma cf Uver in the manufacture of polyvinyl chloride, J. Occup, Med.. 16 (1974) 150--151. 3 Ducatmsn, A.. K. Hirschborn and U. Selikoff, Vinyl chloride exposure and human chromosome aberrations. Mutation Res,, 31 (1975) 163--168, 4 Punes-Cravioto. F,, B. Lambert and J. Llndsten. Chromosome aberrations in workers exposed to vinyl Chloride. Lancet 1 (1975) 459. 5 Gedrigk, P,, R_ MuUer and K. Bechielsheirner, Morphology of liver damage amona polyvinyl chloride workers. Ann. NY Acad. Set.. 346 (1975) 278--2S5. 6 Huberaian, E., H. Bartscb and L. Sachs. Mutation induction in Chinese hamster V79 cells by two vinyl chloride metabolites, chloroethylene oxide and 2<hlnroacetaldchrde, Int. J. Cancer, 16 (1975) 639--644. 7a Infante. P.F., J.K. Wagoner and A.J. MeMichael, Genetic risks of vinyl chloride. Lancet, 1 (1976) 734-736. 7b infante, P.K., J.K. Wagoner, A.J. McMichsel, R.J. Waxweiler and H. Falk, Genetic risks of vinyl chloride. Lancet. 1 (1976)1289--1290. 6 Infante, P.K., Oncoaenio snd mutagenic risks in communities with polyvinyl ohlorld* production facilities, Ann. NY Aead. Sei., 271 (1976) 49--57. 9 Kramer, C.G. and J.E. Mutehler, The correlation of clinical and environmental measurements for workers exposed to vinyl chloride, J. Amer. tnd. Hyg. Assoc., 33 (1972) 19--30. 16 Lange. C.E., S. Julie, G. Stein and G. Veltman, Further result* In polyvinyl chloride production workers, Ann. NY Acad. Sci., 246 (1975) 18--21. 11 Lester. D., L.A, Greenberg and W.R, Adams, Effects of single and repeated exposures of humans and rats to vinyl chloride, J. Amor. tnd. Hyg. Assoc.. 24 (1963) 265--275. 12 Lilis. R.. H. Anderson. W.J. Nicholson. S. Daurn. A.S. Fischbdn and U. Sclikoff. Prevairnce of disease among vinyl chloride and polyvinyl chloride workers. Ann. NY Acad. Scl, 246 (1975) 22--41, 13 Loken, E, snd E. Thils-Evensen. Preliminary report on the medical examination of 286 employees at the PVC plant. Norsk Hydro a.*., Poragrunn Fabrikker, Porsstrunn, Norway, unpublished. 14 Loprieno, N.. R. Barale and S. Baroncelli. Evaluation of the genetic effects induced bv vinyl chloride monomer (VCM) under mammalian metabolic activation: studies in vitro and in vivo. Mutation Res.. 40 (1976) 85-95. 15 MaJloni, C.. Preliminary report on thv careinogenicity bioasaays of vinyl chloride. U.S. Dept. Labor informal Fact-Finding Hearing on Possible Hazards of Vinyl Chloride Manufacture and Use. Wash ington. D.C.. February 1974. 16 Malloni, C. and G. Lefemlne, Carcinogenicity bioasiays of vinyl chloride, Current results. Ann. NY Acsd. Sci.. 246 <1975) 195--218. 17 Mantel. N. and W. Haenczel, Statistical aspects of the analysis of dats from retrospective studies of disease. J, Nall. Cancer. Inst.. 22 (1959) 719-748. 16 MarsteUer, H.J.. V..K. LelbaeH, R. Muller and P. Gedigk. Unusual spknomegsJic liver disease as evi denced by peritoneoscopy and guided liver biopsy among polyvinyl chloride production workers. Ann. NY Aead. Sci.. 246 (1975)95-134. 19 McMichat1), A..!., S.G. Haynes and H.A. Tyroler. Observations on the evaluation of occupational mortality data, J. Occup. Med.. 17 (1975) 128--131. 20 Miller, A.. A.S. Tcintein, M. Chuang, l.J. Selikoff and R. Warshaw, Changes in pulmonary function in workers exposed to vinyl chloride and polyvinyl chloride, Ann. NY Acad. Sd., 246 (1975) 42--52. 21 Nicholson, W.J.. E.C. Hammond. H. Seldmsn and l.J. Solikoff, Mortality experlencs of a cohort uf vinyl ehlorido-pnlyvinyl chloride workers, Ann. NY Aead. Sei.. 246 (1975) 225--23022 Patty, F.A., W.p. Yam snd C.P. Waite. Acute response of guinea pis* to vapors of some new com mercial organic compounds. Public Health Reports. 45 (1930) 1963--1971. 23 Purchase, I.F.H.. C.R. Richardson snd D. Anderson, Chromosomal and dominant lethal effects of vinyl chloride. Lancet, 11 (1975) 410--411. AP00006790 24 Rannug, U.. A. Johansson, C. Ramcl tnd C.A. Waehtmeittar, Th* mutagenicily of vinyl chloride tilt: metabolic activation, Ambio. 3 (2974) 194-197. 25 Shapiro. S., E.W. Jones and P.M. Densen. A life table of preinaaey term [nation! and correlate* of fetal lose. Millbink Quarterly. 40 (1962) 7--46. 26 Tabershaw, I.R. and W.R. Gaffey, Mortality etudy of worker! In th* manufacture of vinyl chloride and Hi polymer*. J. Occup. Med. 16 (1974) 609--918. 27 United States Environmental Protection Atcnev, Sampling and mnalytis ol select toxic substancee. Task 111, vinyl chloride. Contract No. 68--01--2646, Jan 20, 1976. 26 Vetunan, G., C.E. Lan*e, S. Juhe, G. Stein and U. Baehner, Clinical manifestations and count of vinyl ehlorlde disease. Ann. NY Acad. Sei.. 246 <1975) 6--17. 29 Viola, P.L., A. Bifotti and A. Caputo, Oncogenie response of rat skin, lung* and bones to vinyl chlo* ride. Cancer Res. 31 (1971) 616-619. 30 Waxwoiler. R.J.. W. Stringer. J.K. Wagoner. J. Jones, H. Falk and C. Carter. Neoplastic risk among workers exposed to vinyl chloride, Ann. NY Acad. Sci., 271 (1976) 39--46. AP0000679I