Document 9JkG9mXkZ7aGgqO9yboGoLyRe

\ Q. A. DISCUSSION Inquirer: Michael Kay, University of Missouri Research Reactor, Columbia, MO How is coal volatilization process different from nuclear weapons de tonation where refractories are on larger particles? Clearly, many elements display an increased concentration with de creasing particle size of coal fly ash. The size dependence appears to be due to a variety of factors including size distribution of min eral grains in the coal and the volatility, reactivity and stability of chemical or elemental forms that exist in coal. It is well estab lished that those elements (or their oxides) which are volatilized at coal combustion temps are preferentially concentrated on fine fly ash particles, i.e. concentration of condensed volatilized forms is a sur face related phenomenon. Decomposition reactions, e.g. carbonates or sulfates, may give rise to fine particle formation of relatively re fractory elements. Such fine particles may agglomerate with larger particles, again giving rise to a surface related concentration en hancement. A similar argument pertains to mineral grains which may also give rise to fine particles of relatively pure materials. Chem ical reactions may also give rise to volatile species from refractory compounds. For example, it has been suggested that silicon may be volatilized by reaction of silica with carbon resulting in formation of SiO. Subsequent nucleation processes may give ris~ to submicron agglomerates which deposit on surfaces of larger particles. TM " rnt'lmay fc,, hv oomnriirht T.tc7 YTiiTn 17. j j .S. ToTpT R e8Ev-Tfefreetscrata]schooffloIarmoSmdiniubgnelenolzEoogx-ippe-odasiunodrxeiTnoofixn2i,cMo3,lioc7ge, ie \ia c A 9( :$ vi iJ- R. P. Sharma Utah State University Logan, Utah R. J. Kociba and P. J. Gehring The Dow Chemical Company Midland, Michigan -1 L ?e> ABSTRACT H A - f. A single dose of 10 ug/kg of 2,3,7,3-tetrachlorodibenzop-dioxin (tCDD) in CD-I mice produced signs of toxicity includ ing microscopically detectable degenerative changes and in creased weights in the liver, lymphoid depletion and decreased weights in thymus and alterations of various hematological pa rameters (decreased red blood cell count, lymphopenia and neu trophilia). This treatment also increased spontaneous trans formation of lymphocytes in cell cultures prepared from spleens of treated mice. Transformation of these lymphocytes induced by mitogenic agents was reduced. These effects on lymphocyte transformation, apparent at 2 weeks post-administration, were not discernible at wk 4. By 8 wk post-administration, the wts of liver were approaching normal and the degenerative lesions observed microscopically were less severe; although thymic wts were still depressed, no lesions were microscopically discern ible in this organ. At this time RBC counts were normal while mild lymphopenia and neutrophilia persisted. Transformation of lymphocytes, either spontaneous or mitogen induced, showed no deviation from that of control. These results indicate that in mice the toxicity of TCDD, including untoward immunologic ef fects, is reversible in a relatively short time. W, O INTRODUCTION 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a highly toxic contami nant formed in the manufacture of trichlorophcnol and in a number of othe related compounds (4,12,19). It is one of the most toxic chemicals known (other than biotoxins). Studies on various toxic effects of TCDD have in eluded teratologic (3), general toxicologic (6), pathologic (5) and other clinical effects (20). It is a potent inducer of hepatic microsomal en zymes (10) and causes induction of 6-aminolevulinic acid synthetase (9). A 13-wk oral feeding study in rats with different levels of TCDD and re lated toxicologic effects has been reported (7). In addition, there have been implications that TCDD may adversely af feet the toxic to immunological system. lymphoid organs, e.g. This chemical was thymus (2). Gupta esthowanl . to be particularl. (5) found that TCDD was toxic selectivity of to the thymus of rats, mice and other organs in these species. gVousineoai apil g. s,(17d)esprietpeortseodme the immunosuppressive effects of TCDD in rats and mice; subsequently Vos and Moore (16) suggested mune functions. Thigpen etht ata l .the(15e)ffeschtoswedwerae primarily decreased on host cellular im sensitivity to bacterial but not to viral infections. In our recent studies (reporter 299 j ^separately) we have found a decreased responsiveness in mice and rabbits / exposed Using a to TCDD splenic when cell their immune function is culture system, however, canhalilnecnrgeeadsedwitDhNAansynatnhtiegseins.^ ' in lymphocytes from animals exposed to TCDD was observed. The objective of this study was to determine if the toxicologic .-ef fects, particularly the immunologic ones, are reversible with time. This report describes the time related effects in mice of a single exposure to TCDD for periods up to 8 wk. MATERIALS AND METHODS Male, CD-I mice were obtained from Charles River (Wilmington, MA) and were acclimated for 1 wk. They were housed 2 per cage, provided free ac cess to feed and water and kept in an environmentally controlled room with a 12 hr light/dark cycle. At the start of the experiment, the animals weighed approximately 28 g each. The mice were divided into 2 groups; half were dosed with a solution of TCDD in corn oil (containing 5% acetone) at the rate of 10 yg TCDD/kg and the other half were dosed with an equal volume of vehicle alone. Groups of 3-4 animals were sacrificed by decapitation at 2, 4 and 8 wk after treatment and blood was collected for total and differential cell counts and also to obtain serum. The liver, kidney, spleen and thymus were obtained and weighed. Spleen was used for lymphocyte cultures; other organs were placed in formalin fixative, processed routinely and examined for microscopic alterations. Splenic cell cultures were conducted as described elsewhere (13). Sus pension of cells obtained from these organs were cultured in triplicate with or without the presence of either phytohemagglutinin (PHA) or poke- weed mitogen (PWM) in micro-culture plates. After 48 hr of incubation in humidified air containing 5% C02, cultures were pulse labeled with 0.5 nCi of 3H-thymidine and incubation continued for additional 16 hr. The cells were harvested, washed and 3H activity counted in a liquid scintillation spectrometer. The counts were converted to disintegrations/min using a standard quench curve. After averaging the replicates for each culture, stimulation indices with both mitogens (dpm with a mitogen/dpm with no mi togen) were obtained and the animals in each treatment group averaged. Serum immunoglobulins were estimated by electro-immunoassay using ciafriebdamyflraotmedBjerrarbubimte at ntail -. mo(u1)se immunoglobulin by a procedure in an agarose gel system described previously (13). mod The results are expressed as mean of observations with either stan dard deviation or standard error of the mean. Values in control and treat ment groups were compared by t-test (14), using a prespecified p=.05 value. '^ RESULTS None of the mice died due to treatment or showed any clinical effects of TCDD,toxicity. Growth of treated animals was comparable to that of con trols. '4Body wts, organ wts and organ/body wt ratios for selected organs are listed^in Table I. A reduction in thymus/body ratio was observed in the group sacrificed 8 wk after TCDD exposure. The only other organ show ing a change was liver; its absolute wt and the liver/body wt ratio in creased consistently at all intervals, albeit a' significant difference oc curred only 4 wk after treatment. The increase in liver wt was nearly 18:: at the 2 wk interval;-rising to 26% 4 wk after exposure, but decreasing to $ only 11% by 8 wk after TCDD treatment. Upon microscopic examination treatment related changes were observed in liver and thymus. The lesions were similar to those described else $ where (13) and the incidence at different time intervals is summarized in Table II. Liver lesions included degeneration or necrotic changes at 2 and 4 wk after treatment whereas fibrosis with increased leukocytic infil- 300- T. X i r f t * / , P ir f < o+ 1 +a- 1 to r^. ot+o ! c+o 1 LO o+> i o o. l I 1 1 a _j <oCr o to tS i UJ -oJ >< z-- LxU l/) J-- z <" IC J-- h--- LZU 3 L^U O ULU Ll. SLcli o CC H h- < UJ o O LU --2: o --Lu U. -- O J-- <(/) XC--J zes LU < z< aa : o a z< >ao03 , __ UJ -J < Ol *LO w V--1 1 +1 I' o& o ^r to to +J |-- --] C o M Ol <0 cc Ol CM COO d. d, oO+l +[ *C3M- f-- CM * co c n o CM d, d. Co+O1 L+f>1 Lf) CM CM ^3CM 00 <-- d, d( t+o o 1 CC4MO* | CM CM s.ccu j-- OCT O to to o o, o, to o coo o. o. o LO O o, o. TC? 03 oi c Ol QCUJ C+O1 oo Ct+oM1 i+n 1 CM +1 PO ^C+M3-1 r+o ] CM o o o d Od *+cJ Q. O) i/> too o CM o in o in CM oO 0) 12 e o, o, o, d. o, o, Ol + 1 O+l o Oo+l 1 C+M o+ o+ 0U3) <TJ as-> o oo oO OOl o1-- U) -a__i E ->C* 1-- .--, Ol coo co o o, o, I+'-. rt+--o do oo o, o. to+o 1 t+o a do o3- o o, o. o+ CM 1c^+o-- oo CoM CM o d, ot r+-* o r+*^ o do oo CM r*o Oo o, d. O+l +1 f-- t od CM oO O o. C+O o i+n O dO C O) -C +-> o Oa) +oj c +J . CaD. U X 01 ** Q3 . Vo cn CM/) +Q->J V) M -M Ol c c 3 Q in O CVL +-> ro O +L-J Co u <>u o <o(/J)J. ai .j >1 -a o co -*5->Wa i a3 O(- o i- +cC-U> (A 01 0) (C 0) *Er <s*u- 3 h- l-- '3-, CO, cC+oO i+n CO t+o 1 4* cri co 00 .o X I a 0) 4u-> 4r-o> o 4i->. "O 4C-LJ i0 c o as-i c o as- (_> i-- u j-- CM ro o+ C+M1 <3 <sT t. a> a. Q_ 3 EO S- i/> O r-- i- e JO o S- _*oo ai 4-> +ocJ (a13t u fO D) o E L. 4-> c oj S' 0C)L r0 </> > QJ c_> H 4- "O O E +-> C oc CO ft3 <J CO + 1 00 ti c (O 0J >0 c er a* ros : .ao to * 301 tration was apparent at 8 wk. As seen in Table II, a progressive increase ^ in the incidence of liver effects was observed when tissues were evaluated in a blind random fashion. The thymus effects included regression of cor tical area, depletion of thymocytes and occasional pyknotic foci, but these were seen only in samples obtained at 4 wk after TCDD treatment. A gradual development of thymic changes that took nearly 4 wk, with a rever sal of discernible effects by 8 wk, was evident from the results in Table II. No changes in kidney were observed. TA BLE I I . INCIDENCE OF LESIO N S IN L IV E R AND THYMUS OF MALE MICE TREATED WITH A SIN G LE DOSE (1 0 p g /k g ) OF TCDD AND S A C R IF IC E D A FTER D IF FE R E N T IN TERVALS3 Duration After Exposure (Weeks) Control Liverb Thymus Treated Liver0 Thymusd 2 0/3 1/3 3/4 0/4 4 2/3 1/3 4/4 2/4 8 2/3 0/3 3/3 0/3 Sections were examined microscopically in blind random fashion. Kidney showed no remarkable change in any group. Numbers indicate incidence of lesions/total number of animals examined in that group. ^Lesions in control liver included vacuolization or slight degeneration of hepatic cells. cL1ver in these groups generally showed slight to extensive diffuse degen eration or necrosis, dCortical atrophy with depletion of thymocytes seen in thymus of animals sacrificed 4 weeks after treatment. Hematological examination (Table III) revealed a significant reduc tion in the total number of erythrocytes at the 4 wk interval. This change was not noted at 8 wk post-exposure. Total leukocyte counts showed no change at any of the sampling periods. A consistent increase in the number of segmented neutrophils and a corresponding decrease in the number of lymphocytes was observed at all intervals. Splenic lymphocyte cultures at different time intervals showed that at 2 and 4 wk after TCDD treatment there was a marked increase in DNA syn thesis in unstimulated cultures. Although the extent of average Increase was similar at these 2 periods, there was greater variation at 4 wk, mak ing the difference statistically non-significant (Table IV). At 8 wk, up take of tritium was similar for both control and treated groups. When these cultures were supplemented with either PHA or PWM, the resultant mi togen-induced stimulation was decreased considerably at 2 and 4 wk after treatment with TCDD, but control and treated groups were similar in this respect at 8 wk post-treatment. Estimation of serum-immunoglobulins indi cated that a single exposure of 10 ug/kg TCDD did not produce any marked change in this parameter at either period of sample collection (Table V). DISCUSSION Results indicate that TCDD in a single dose of 10 yg/kg is toxic to mice and the toxicity is evident by decreased thymus wt, increased liver wt, alterations in hematological parameters and histopathological lesions, primarily in liver. In general these toxic effects' seem to be reversible and the reversal may be evident as early as 8 wk after exposure toTCDD. 302 TABLE II). SELECTED HEMATOLOGICAL PARAMETERS IN TCDD EXPOSED MICE Mean + SE of 3-4 animals per group ^Stimulation index = dpm in the presence of mitogen divided by dpm without mitogen *Significant difference (p<.05) from respective control group 7 l/l xz o . O .C M . CM.-- . CM.-- . o + + + 1+ + 1+ 1 c O i-- CM i-- i m1 o; UJ t 1 '' in CM .CO . CM ,.-- , + 1+ [ o CM CM -- 'cm 1 CO CO c o E * ] to r - CO O CM O <-- 01 <3- CO i ) CO O lO 4-> CM O CO CM m co > , CM CM O o * * x z r--. co 1-- CO CO CM o . CM +1+ 1 +1+ 1 + + 5 : C O 'c m 1 a m m -- u co r - . c o m c - =r A3 in mm O CM JZ K t IX o, o* S- M- 4-J 3 tar; mm f-- CM CTl CM CO O CM O ) > tn o in CM -- < f r* * co co r+-~ 1--+ 1 r --1 ^ K r - . cm .CM . r+-- m+ cm in R o. C i-- J X *d* co cm c n 3 Oo CTr-- .O . d . -- . 0 . 0 . i- m + 4- ++ r - cn cm o >-- o CM CM CM CM CM o X i- E +j s cu o o t- 01 * ai o . t-- in O r-- lO CO > , I-- to 1- CM in co *r* L o .-- ,o 4-> a i o . o , o . o , O JO ID o ++ CM <-- ++ m 'M* in co 01 E O . =3 O CM r-^ cn r " . Q to c ai X CO CO CO CO 0 0 I- 01 4J E aJ O Ml i- *r* +- TJ c -- * a (-- "O -- * a 4-> -r- a o U -M a ) i/t 4-> AJ 4-> n j + J to i- 0 ) t - C 0 ) C V C 01 qj v> CD O 1- O L . o u <+- a i (_> 1-- t-J l-- <_> l - 4- -c *r* -M "O c aA3. nc QJ u <- u 3 to CM O H - (/i CO r- 01 'r a 3 Q . 1 1 cn^ X *- <0 U J to > 4t Ui (-1 a z z o < -1 3 cc l- r a t/> o o Z (_) UJ 1o o cn I- + --X e cn 3. a zo <-- fA U . Ui o ?- UJ O </) oo XQ a. X -1 >- < _i o o -- UJ X --1 U J 13 ~3 ZS a. -- m in > oc CQ U i .U I u . ^< < f - UJ a- o 3-- X UI -z z a -- X -> X l- i> 1 UJ -1 CO < 1- -Z 4J X cu Xl X ai "O c --4 c O 4-J A3 a e er X ^pJ O CO co m ^3' ^ oo * CO 0 0 in # i-- CM cn r-- m o-- CT> CO + 1+] to m+ ll+t>l m o -- O ID CO CM i-- < r i-- p-- *T CO i-- CM CO r- CO CO in cm m i- 0 , 0 , CM .CM , 0 , 0 , + CT> i+-- t+o c+n + 1+1 m Vo o^ m O CM co i-- d i-- L f) f--r-- d VI 01 Di f--- o a i +-> L J *r-- U3 o 44 3 O C Qa - 4-> 3 * m i-- to r-- cn oo cm cn 1" ^ r** CM V CM CO ID CM r- . cn OO CO co CO o (O CM id cn A I* r - . cm *T ,CM , ^+ 1C+J>1 cn to r-M m CO CO tD CM cm m o to ID 00 CO CO O CO CM O CO VD CM CM CM 3 TO "O a i a i 4-* f--* A ^ u i 1-- AJ CL o a j o a> o a i 3 t- u U L- u u O 4-> (-- 4-1 l-- 44 1-- L- c c c OQ o a oo O Q CJ o o o U u <_> V - H-- h S- ai u 1/1 V) trt u- 3 to 01 a i a i OJ oa. a j 01 01 EX r LU CM ^3" CO 303 TA BLE V . SERUM IMMUNOGLOBULINS IN MICE AFTER A SIN G LE DOSE OF 10 u g /k g TCDD Group Control Treated Serum Ig Levels3 After 2 weeks 4 weeks 8 weeks 1.37+0.23 1.13+0.10 1.24+0.07 1.13+0.19 1.20+0.13 1.09+0.16 aValues are ratios of total serum immunoglobulin to that of a pooled mouse serum sample. Mean + SE of 3-4 observations per group. The severity of pathologic changes in the liver was most pronounced at 4 wk after treatment. At 8 wk liver lesions were more of a chronic type, i.e. fibrosis. The incidence of thymic changes was highest at 4 wk post treatment and even though a decreased thymus wt was noted after 8 wk, histologic changes were not observed at this interval. In another study where mice were given repeated weekly doses of different amounts of TCDD no effects on the thymus after 8 wk were noted (13). These findings indi cate that the toxic effects of TCDD to this organ are not only reversible but even with continued exposure there is an adaptation. The single dose oral LD50 of TCDD in male mice is reported to be 114 ug/kg (18). Following a single administration more than half the total body burden for TCDD is accounted for in the liver in a sensitive strain of mouse (9). According to the data presented by these authors, the con centration of TCDD from C5 7BL/6J mice liver disappeared at a half-life rate of approximately one wk. This value is considerably smaller than the whole body half-life value obtained in rats (8,11). In view of these ob servations a major fraction of TCDD in the liver of mouse may have been eliminated in 8 wk, while it may be more persistent in other species, e.g. rats. If this interpretation is correct, the effects of TCDD in liver and other organs will disappear in this time interval. A marked effect of TCDD exposure was seen on the splenic lymphocyte transformation in cultures. A single dose of TCDD caused a considerable increase in spontaneous blast formation in splenic cultures obtained from )i treated animals. This finding was also observed when exposure of TCDD was repeated once a week for 8 wk (13). Although the implication of this find ing is not clear, nor is its mechanism understood currently, this effect is it most striking 2 wk after administration of 10 pg TCDD/kg. After 4 wk the effect persisted, although there was great individual variation in these * parameters. In another study (data not reported) we exposed adult (4-5 mo old) mice to the same dose of TCDD (vs. growing mice in present report) and a similar, although less extensive, effect was seen when the spleens . were cultured 2 wk after treatment. Another important consideration of i* this increase in spontaneous lymphocyte transformation is decreased respon siveness to mitogenic agents giving rise to smaller stimulation indices in 9 t treated animals. This is indicative of decreased responsiveness of the immune system to antigenic stimulation, also confirmed .in another study (13). The major finding of this study is that both spontaneous blast for mation and mitogen induced stimulation return to normal in 8 wk after TCDD exposure. This further supports the argument of the reversal of toxic ef fects of TCDD in mice within a relatively short time. It is difficult at present to extend these findings to an accidental human exposure to TCDD since it is well known that considerable species variation occurs in response to this toxic chemical. But the differences in physiological disposition would alter the rate at which the body is cleared of the chemical and if a sublethal exposure occurs, the effects probably can be reversed with time. The immunologic effects were not 1ast- i. 304 ing whereas the hepatic effects persisted. Perhaps accumulation of TCDD in liver may be considered a defensive mechanism, at least insofar as the immunologic alterations are concerned. ACKNOWLEDGMENTS The valuable assistance of Roselle Lisowe and Ruta Kalnins during these studies is gratefully appreciated. LITERATURE CITED 1. Bjerrum, 0. J., A. Ingild, H. Lowenstein and B. Weeke. 1973. Carba- mylated method. anItn:iboQduiaenstituastediveforImqmuuanntoietlaetcitroonp hoofrehsuimsa.n IgG. N. H. A routine Axel sen, J. Kroll and B. Weeke, Eds., Universitetsforlaget, Oslo, pp. 145-148. 2. Buu-Hoi, N. P., P. H. Chann and G. Sesque. 1972. Organs as targets Nofa tduirowxiisns e n(2s c,h3,a7ft,e8n-te5t9r:a1c7h4l-o1r7o5d.ibenzo-p-dioxin) intoxication. 3. Courtney, K. D. and 0. A. Moore. 1971. Teratology studies with 2,4, T5-otxriiccohll. oAroppphle. nPoxhyaarmce. tic20:a3c9i5d-4a0n3d. 2,3,7,8-tetrachlorodibenzo-p-dioxin. 4. Elvidge, D. A. 1971. The gas chromatographic determination of 2,3, 7.8- tetrachlorodibenzo-p-dioxin in 2,4,5-trichlorophenoxy acetic acid and 2,4,5-T esters and 2,4,5-trichlorophenol. Analyst 96:721-727. 5. Gupta, B. N., J. G. Vos, J. A. Moore, J. G. Zink! and B. C. Bullock. 1973. Pathologic effects laboratory animals. Env. Hofith2,. 3P,7e,r8s-. tet5r:a12c5h-l1o4r0o.dibenzo-p-dioxin in 6. Harris, M. W. al biological , J. A. effects Moore, J. of TCDD G. in Vos and B. laboratory N. Gupta. animals. E n1v9. 72m. t h .GePneerr s . 5:101-110. 7. Kociba, R. J.,P. A. Keeler, C. N. Park and P. J. Gehring. 1976. 2.3.7.8toxicity sTteutdryacihnlorraotdsi.benTzoo-xpic-doil.oxAinp p l(.TCPDhDa)r:m.Res3u5l:t5s53o-f57a4.13-v/eek oral 8. Piper, W. N., J. Q. Rose and P. J. Gehring. 1973. Excretion and tis Esunev. diilsltt hri. buPteirosn. of 2,3,7,8-tetrachlorodibenzo-p-dioxin 5:241-244. in the rat. 9. Poland, A. and E. Glover. 1976. Stereospecific, high affinity Dinigo lo. fC2he,m3,. 7,82-5t1e:t4r9a3c6-h4l9o4r6o.dibenzo-p-dioxin by hepatic cytosol, jbi. nd 10. Poland, A. and A. Kende. 1976. 2,3,7,8-Tetrachlorodibenzo-p-dioxin: environmental contaminant and molecular probe. Fed. Proc. 35:2404- 2411. 11. Rose, J, Q., J. C. Ramsey, T. H. Wentzler, R. A. Hummel and P. J. Gehring. 1976. The fate Plohwarimng. single and repeated 36:209-226. oofra2l,3,do7s,e8s-tettoratchehlorrato.dibeTnozxoi-cpo-ld. ioAxpipnl . fol 12. Schwetz, B. A., J. M. Norris, G. L. Sparschu, V. K. Rowe, P. J. Gehring, J. L. Emerson and rinated dibenzo-p-dioxins. C.E nGv.. mGetrhbi. g.P a r1s9. 73.5:87T-o9x9i.cology of chlo 13. Sharma, R. P. and P. J. Gehring. 1979. Effects of 2,3,7,8-tetra- chlorodibenzo-p-dioxin mice after single and (TCDD) repeated on splenic exposures. lyAmnpnho. cnyt. ey.trAacnasdfo. rsmcati .ion in (In 14. press). oStf ees lt ,a t Ri .s t Gi .c s D. and J. H. Torrie. 1960. , McGraw-Hill, New York. P rinciples and Procedures 15. Thigpen, J. E., R. E. Faith, E. E. McConnell and J. A. Moore. 1975. sIunrcereatsoed2,3s,u7s,c8e-ptteitbrialcihtlyortoodibbaecntzeor-ipa-ldiionxfienc.tioni n faesc at , siemqmueulna. of expo 12:1319- 1324. 16. Vos, J, G, and 0. A. Moore. 1974. Suppression of cellular immunity % in rats and mice dibenzo-i-p-dioxin. byInmfact.erAnraclh . tArel laetrmgeynt with 2,3,7,8-tetrachloro47:777-794. 17. Vos, J. G., J. A. Moore and J. G. Zinkl. 1973. Effect of 2,3,7,8- mtaeltsr.achlEonrvo. diHblethnz. o-Ppe-rdsi. oxi5n:14o9n-1t6h2e. immune'system of laboratory ani 18. Vos, J. G., J. A. Moore and tetrachlorodibenzo-p-dioxn J. G. (TCDD) ZiinnklC.57B1/19674m.ice.ToxiTcoixtiyc oolf. A2,p3p,i7. , P/iarm. 29:229-241. 19. Woolson, E. A., R. F. Thomas and P. pFooloydcchhleomr. dib2e0n:3z5o1--p3-5d4i.oxin content 0. in sJe.lecEtnesodr.pest1i9c7i2.des,Surjv.eyAogf. 20. Zinkl, J. G . , J. G. Vos, J. A. Moore and B. N. Gupta. 1973. Hemato logic and p-dioxin clinical chemistry effects in laboratory animals. Env. oHf l2th,3. ,7P,e8r-st. etr5a:c1h1l1o-r1o1d8i.benzo- 305 V ENVIRONMENTAL POLLUTION t Dioxin and Soft Tissue Sarcomas There are two kinds of data involved in the current debate about the link between soft tissue sarcomas and exposure to 2,3,7,8 TCDD ("dioxin"). The first kind might be called "after the fact" data. They consist of several soft tissue sarcomas that turned up in three studies, two at Monsanto and one at Dow, and were noticed after the fact by investigators at NIOSH. These investigators then looked for other soft tissue sarcomas and found some at two Monsanto plants. Whether there are four or five or seven such cancers depends on how one defines exposure, but in any case these are reported to be in excess on the basis of conven tional statistical calculations. These calculations are suspect because they were made after the fact. To see this, notice that there have been some 7000 workers with potential exposure to dioxin nationwide in some eight plants (NIOSH data). NIOSH observed cases coming from two plants, and calculated "excesses" based on the populations of those plants. What they should have done, and are now in the process of doing, is to follow up the whole 7000 workers and to relate whatever number of soft tissue sarcomas are found to this popula tion of 7000. It may be that this process will turn up a true excess, but until it is done the significance of the currently known soft tissue sarcomas cannot be evaluated. The second kind of evidence consists of a series of epidemio logic studies directed specifically toward soft tissue sarcomas. These began when a Swedish group did two studies comparing cases of soft tissue sarcomas to matched controls who did not have cancer [1,2]. Both groups, or their next of kin where necessary, were interviewed by telephone about past chemical exposures. There was more exposure to phenoxy herbicides, which could have dioxin as a contaminant, in the cases than in the controls. Exposure was estimated to be associated with a six-fold increase in risk. The studies were criticized by other investigators [3,4]. In brief, the method of obtaining exposure information was prone to bias, and the duration of exposure of the cases was suspiciously short. Other technical problems also surfaced, and other investi gators attempted to confirm or refute the findings through inde pendent studies with different designs. 003*733 Two general mortality studies of Swedish forestry workers and railway pesticide sprayers showed no soft tissue sarcomas [5,6]. A similar study of Finnish herbicide sprayers also showed jio soft C AH, SUB TO PROTECTIVE ORDER- Dioxin and Soft Tissue Sarcomas ' Page 2 tissue sarcomas [7], Finally, a N e w Z e a l a n d study, s i m i l a r in design to the Swedish studies but with more attention paid to controlling possible bias, did not confirm the Swedish findings [4,8]. In summary, we have a small number of soft tissue sarcomas among two groups of workers i n v o l v e d in the p r o d u c t i o n of 2,4,5 T. Their significance cannot be evaluated. We also have six epidemi ologic studies, two of which show a relationship between soft tissue sarcomas and dioxin and four of which do not. The only thing that seems clear is that the NIOSH nationwide study of dioxin exposed workers should certainly go forward, and that the National Cancer Institute should be encouraged to conduct a study based on the Swedish design in order to further clarify the situation. References 1. Hardell, L., Sandstrom, A. (1979). C a s e - c o n t r o l study: Soft tissue sarcomas and exposure to phenoxy acetic acids or c h l o r o p h e n o l s . Brit. J. Ca n c e r 39:711-717. 2. Eriksson, M. et a l . (1981). Soft tissue sar c o m a s and e x posure to chemical substances: A c a s e - r e f e r e n t study. Brit. J. Ind. Med. 38:27-33. 3. A d v i s o r y Committee on Pesticides. R e p o r t on p h e n o x y acid herbicides (1982). U.K. Ministry of Agriculture, Fisheries and Food, Great Westminster House, London. 4. Smith, A.H. et a l . (1982). Do a g ricultural c h e m i c a l s cause soft tissue sarcoma? Initial findings of a case-control study in New Zealand. Community Health studies 6:114-119. 5. Hogstedt, C., Westerland, B. (1980). C o h o r t s t u d y of causes of death of forestry workers with and without exposure to phenoxy acid preparations. Lakartidningen 19:1829-1831. 6. Axelson, O. et a l . (1980). H e r b i c i d e e x p o s u r e and t u m o r mortality. An up-dated epidemiological investigation on S w e d i s h railroad w o r k e r s . Scand. J. W o r k Env. H e a l t h 6:73-79. 7. Riihimaki, V. et a l . (1982). M o r t a l i t y of 2 , 4 , 5 - t r i c h l o r o phenoxyacetic acid herbicide applicators in Finland. Scand. J. W o r k Env. H e a l t h 8:37-42. SUBJECT TO PROTECTIVE ORDER. D'uoxm and Soft Tissue Sarcomas Page 3 8. Smith, A.H. et al. (1983). The New Zealand soft tissue sarcoma case-control study: Interview findings concerning phenoxyacetic acid exposure. Chemosphere 12:565-571. WRG/an 08/12/83 SUBJECT TO PROTECTIVE ORDER? T / CG3732 jnj :r i K * SUBJECT TO PROTECTIVE ORDER.