Document ByXordr3p98N9Q17DgRXJGv5w

x a r y Communications WE rcporr here prcliminnry invrsdgations of the povsibility thvr men cxposcd to ambicnr bcnrenc may show $rructural chromosome aberrations in lymphocytcs cultwed from rha peripheral blood. T h c toxic acdon Of benzene on crythropoirsis and myelopoiesis has becn rccogaisod since the early years of rhr: prescnr c c n ~ w .11 js now becoming recvgniscd that benzene is prohshly il leukemogen and is especially liablc 1'0 cause erythruleukznain.1 SUBJECTS STUUIED 20 men were cmrnincd from a facmry in which it had been fnwd an 1962 that belnene wa!i being used a$ R anlvenr. Sificc then toluene, frcc from benzene, hat becn used irisread of henaenc. Thcse rnm 8i-e all convidered ro have heen bxposdd tu smbicnt benzene h r periods varying fr'rcm I TO 20 years. The facrory was visitcd on twu occacionr--.in November, 1964, and in Jiuiuary, 1965. At the fimt visit blood samples wci-c mkcn frQm14 men xelectrd bccause they had shown nculropcnia in 1962. Study of cells horn the blood-cultures provided primafscic evidcncc for tbc prcsmr;\:of an unusunl number of cclls wirh dmmosome aberrations. At rhc second visit blood mnplrs wcre obtained from 6 udditional cxposed workrs and a160 from 5 othcr men employed in aituarions in which cxposurc to benzene could not have occurred. Thc cclls from cultures established 3t thc second visit werc counted and analysed s'ithout the cytolopisr knowlng the source. --significantly increased (f 54OCl.n 1 045 2 F >0-02). 'I-'he differcncr is 'further crnphasised by the complexity of the abrrmtions in Lhr C, cctlv (rnblz 11). This may bc asscssrd by considering thr numbcx of Chi'orno8ome brcaks requircd to produce thc obsrrvcd abcrrarion or aberrations, and cxprsssd as the menn number of breaks pcr C, cell. For thc exposed workcs the numbers of breaks varied from 1to 6 (mean 1.681, while in the conmh &he mean number was 1.22, all but ctne cell requiring a singlc break. The numbcrs of C, cclls in the rrgposcd wurkers are grearer t h i in the controls but riot significantly SO (x*= 1-170 0.30:,P >0-20). Wc have cvidence from ASSESSMENT OF AIII3RRATIQNS Qur approach to this probIcm has hccn idential to that for rhe stuucly of radiation-induced nhrrrntims. We scored the numbers of cells containing unslnblt abcrrations (C,cells) and of &ow with stable abcrrarions IC, cells). C, cclls arc those with dicentric, uicentrk, or ring sluomasomca, or with one or morc rcwtric fragmentr, rirhcr alonc or in association with these abnormal chromosomes. Such cells are Fonsidcrrd unstable in illat they are unlikely to survive more than two or h e d i v i s h c , whilc thcro is no rcasun why rcmmgcmentr of chremaaornu matcrhl, producing recng'&iriblyabnormal rnotloccnuic chmrnQsomc6, should haw an impaircd cnpribility of-survival on division. ramtion studies that the nurnbcrs uf thcnc cells ccnbritu:t a less sensirivc indicnior of a radiation effect 'fiu- IS undcrsrandable, for by definition the great mal. r..:. c t C, cclls are microscopically recofisablc, bur ~k1r.r ~ U S I _ _be many stable chromUroinc rcarrmg-3- . .r. 1 lch Cannot be driectcd in this way. The !?+ fir$?,a yig~iificantincrcaea in C, cells is not surprising 3 -rr.mstances in which the yield of C, cells, w b I c $:qri?rantly increased, is smdll. 'L'he numbcrs of C, and C,ceilr werc compnrrd with those in the culrura fmm the on-sitc cenrrols uiid those from cultures cbtabtiahcd from rnnales, rondornly selccttrd from chc population, banvcen rhc ages of 15and 64years. Ir!all instances the cuiturcs wcre hutvested after betwban about 40 and 50 hours, iadusive of 3 hours with added coldiicine. The nccrssiry for srandwdishg on early culture times has bcea discusscdby Buckron and Pike.!! Radiation exposurc can producc ccrmparab!c rypcs I aberrations. We inquired, thcrcfoIe, inlo ihL i'xtcnc which the crposcd workers had been Inadlztri! fr4i medica purparcs. None had had rndiothcrilpeurir cxp = l m , rind the history of diagnostic expusurc--lmrinly rn& miniature radiography-is comparable to that for CIUT controls, The mustbcavily exposed marlhad had bevcrd b a : ~ c~xaimina- R65ULTS tmns of the gastrointestinal was, md hc 41owtrd only a Thc findingc in thc exposed workers, Lhc on-site single C, cell copraining an rctntrit t r a g n c n t ; this c o n t r ~ f ~a,nd the males from the gcncrd population was probably wichout si.gnifi~flceI. Wc arc confident arc shown in ublc I. Thme from thc on-site con~ols that radiation exposurc is nor rhe cy1annr)on for the w d thc randomly sclrcred males do not diffrr sign&- fmdings. candy, and may be combined fur comparison with thc workem Wh.cn thc number of C,CGUSin prcparntions fromlthc: workers w e cornparcd with those from the combined W7s m e indcbtcd TO Dt',1.Wwd-Devirr, c h i c l medical nficcr, and nf. S. G Raidaford, of Hcr Ma)Cfity'$ acKfiCy hSpesturatt, for rhcir help and advisc, and Jlsu tfi die mctisd officer and rralr ot rhc factory at which rhc studies were c1i-m. -controls, --.-. t-he nu-m-.bers in the-__workcrs arc found .-__ to be I 2: dVrikowllinninni,g'EE. .C.B..SiTiitfnc,w0.A. rNrm. IwndJu~rItXr./ m d . ONrr 1P62 .Y,Mcd. 1$64, Z i l 11, 161. , R72. 3 , Ruckcon, K. E., Pike,M.C. Inr. 7. Rad, B i d . 1966,B, 430. I.