Document 2araYd059BoLjn1nx8Jxag5g

.V;:v-;v>.. .-> ' /'*-v> 7^'r-: ; . !|r| - , UXrfQTVks. -'v -_- ^ 'r*T.v- .'. -s. * , . . . .-.' " *.-. ..-- . : * ______ ; ^'t. *;-V* I ..IT::-'. - *] J ';.r.' v-. L R&S 024296 > \' 3; <i > iz . i. ,i t Iii ' 1 > '*'.:"!.:.' v\- : ', ''''* ' Volume 49 Number 2 . : January 1982 \ -A; : Original Investigations J. G. Filscr, P. Jung. H. M. Bolt: Increased Acetone Exhalation Induced by Metabolites t Halogunated Ci and C, Compounds K. Bergman: Reactions of Vinyl Chloride with RNA and DNA of Various Mouse Tissues in vivo 131 P. K. Dudoja, A. Mahmood: Effect of a Single Oral Dose of pp'DDT on the Absorption of Nutrients in vitro and on Brush Border Eri/ytnes in Rat Intestine 139 M. Ando: Dose-Dependent Excretion of DDEn,1-dich!oro-2.2-bis|p-chlorophcnyljethylene)in Rats 149 C. H. Henning, W. Forth: The Excretion of Thallium(l)lons Into the Gastrointestinal Tract in situ of Rats 159 G. B. Gerber, J, Macs. B, Eykcns' Transfer of Antimony and Arsenic to the Developing Organism 1GS L Busk. U. G. Ahlliorg: Retitml (Vitamin At as a Modifier of 7-Aminofluoreno 2-AcetylArrunofluorene Mutagenesis in the Selmonullu/Microsome Assay 175 L. P. A. de Jong, G. Z. Wolring, H P. Benschop. Reactivation of Acetylcholinesterase Inhibited by Mothamidophos and Analogous (DdMuthylphosphotomidates Indexed in Current Contents Meeting Announcement Second International Workshop on the Application of Tissue Culture in Toxicology June 2-4, 19S2, thissrludden, Stockholm, Sweden Details fiom Dr. Erik Walmn, University of Stockholm, Unit of Neurochemistry and Neuro toxicology, Enkopingsvagen 126, S 172 46 Sundbyberg. Sweden Meeting Announcement European Society of Toxicology (Future Meetings) Tel Aviv, March 21 -24, 1982 (organizer Dr, Giber) .^ .... J- r ,,-.y :'i-'s-r ;: 'a '1 Springer International Arch Toxicol ISSN 0340 5701 ARTOON J<t l?l 107- 184 (198?) lurm.ition tbO(3~J<t.sui:su.'i';h) will appear Cu of each volume i$ DM 188.00 :"S lor back-volumes are avail' In ailUition. wo also offer ' nns in Hi nim and 3b mm micfoficin*, Correspondence .:r phons should bn addressed Allow si< weeks for all f('.-i:tiviii All comnwinica. `intn old and new addres '-.I anti sfu wld be accoin ; i.ibei (tom a loconi issue .Animal subscription rate: 3 IJOatjtjand handling _ erruriid with prepayment .od t o lddrnssed to: Springer li : . Service Contor Sticnucus. aeC incus, N J. 07004, USA. ''133. Toll!* 00-23175904. tries Annual subscription rate . postage and handling. Airmail n:st only For Japan, postage id Lifted) and handling is >rs can cither be placed with ft; ' sent directly to: Springerrner Plat; 3, D-1000 Berlin 33, i-Vi 01 rrt;>i:i I . :--Uj.;r,;..t i'l dr 3. i r.............. t, .i | . iO .rn.il Production ., j t'.icn 100 380. Tel (062 21I4B7-331, Y: . Ns-.-. Vurlr Inc . ' 'A;.-. Vnik. M.Y 10010. i 7 82 CO T..'i'r 00-33? 322 AdvijMiSfimiMits: ' ,-`f`^*:ri'jiirYim |^J7t ` '0 i'ji ,<5 8? 1031.* ' \........ .ft f`4*9 ()rifilial Investigations Incruuscd Acetone Exhalation Induced by Metabolites of Haloenated Cj and C\ Compounds .1. (i, Filset. I', .limn, ami II. M limit \'iii-ilune he I uik.iii'itie. I'lMtiuaki'l-'-.m.l'-V' li.-titi.t dvr l.nncrwtat. i I'u'ie /.ihlh.ii iu'i Sh.n>.c Iii.'im '.lie.- ' K.lcril Krpuhli, el < 101 in.itis Abstract. Rats wore exposed. m a closed desiccator j;ir chamber, to COncctUiaUolls nl vai ions lialoecnalcd (. I and C; Compounds ill kvhich the nict.iholi/im: capacities were -i.iturdiL'd I conditions). Within ihc exposure period ot 3il It loncentrauons ol the xcnohiotic tiiul of exhaled acetone wl-10 monitoicd in the tins phase ot the system, Ihc quantitative c.Mciii of acetone exhalation w:,s dependent on the individual compountl examined Acetone exlinltiiton was stimulated in presence of vinyl chloride, vinyl bromide, vinvl llnoriilc. vmylidene lluoride, civ* mid tratts-l ,2-di* chlorocihvlcnc. trichloroethylene, perchloroethylene. methylene chloride, chlorolorm. carbon tetrachloride and 1.1.2-triehloroethatie. No stimulation of acetone exhalation oecured with l.l.l-trichloroethane and with the i etc re lice Itxdrocaibon n-licxanc Also, acetone exhalation was evoked bv inlnsioiis ol citltci lluoioacctaic ot chloio.icetate. two anticipated or proven metabolites ot some halocthy lencs. the mtnsion talcs ot which were based on calculations of the metabolic talcs cmylidene Iluonde and of vinyl chloride, respectively. Kev words: Acetone production - 1 lalomethaucs - llaloelhanes -- 1 lalocilixlcncs Iiilmdncliiin I n prew tons nv- csl teal tons 11* tlsc't ci a! il; s. J -1 Net and 11* dt i n.st 11 w c have lound that some li.doetlnK ites caused acctoncnn.: in rais 1 his clicet was not due lo the lialoctlu lencs themseho'. nut t" meiaNdnes tlicrco: tl-ilser ami Bolt !l>Stl) As an explanation we haw .uK.tUvC.i tw'o rlitietenl theories. One possible mechanism il-iNct and Holt l'*'Oi -.\lu,.,i oticiit to contrii'iiie to acetone v-id . alpri/il. UU...U, I tf f ilsy: trOii-s'oi c ui.m oi07'S 02.00 R&S 024297 : ;y-Vv, e' ; 'V* J. G. Filter ct al. formation was that the haiogenated acetic acids formed, c.g., fluoroacctic or chloroacetic acid, inhibit enzymes of the citric acid cycle, along with suggestions of Jaeger (1977) and Jaeger ct al. (1977). The second theory to explain the hnloeihylcnc-inducod acetonemia (Bolt ct al. 1981) was that increased production of acetone were an ultimate consequence of metabolic effects subsequent to alkylation of cytosolic coenzyme A by reactive intermediates of the haloethylencs. c.g. the epoxides. This idea was supported by evidence ot alkylation of cocn/.yme A by vinyl chloride metabolites in vitro (Bolt ct al. 1981) and bv theoretical considerations (Schoental 1976). Further studies on the mechanisms underlying to the observed acetonemia arc necessary. The present investigation serves to prove or disprove the above theories by comparing a larger series of haiogenated Ci and CS compounds of widely dissimilar but well known metabolic and toxicological behaviours as to their ability to increase acetone exhalation in rats. The experiments used our desiccator jar chamber (Bolt ct al. 1976) as an exposure svstem for which pharmacokinetic descriptions have been published (Filscr and Bolt 1979, 1981; Ilallier ct al. 1981). &>'-, - ms f&e&f S^': Materials and Methods Materials. Vinyl fluoride and vinylidenc fluoride were donated by Dyn.unil-Nohel ACi. Troisdorf (FRG). Vinyl bromide, 1.1.1- and 1.1.2-tricliIorocthnne were purchased from Aldrich Europe. Brussels, Belgium, and n-hexanc, carbon tetrachloride, chloroform, diehloromethane from Merck AG. Darmstadt. FRG. Other materials were of the sources previously indicated (Filser and Bolt 198(1). All the haiogenated hydrocarbons were routinely checked for purity. When necessary, they were redistilled prior to use in order to achieve a purity of at least 99'f. During controlling the exposures special attention was paid that no peaks occurred in the gas chromatograms ind'eative ol solvent impurities. Exposure of Ruts, Male Wislar rats (from Ivanovas. Kisslegg. FRG) ol 251) g were used. Usually two rats were simultaneously exposed to one of the haiogenated compounds in the closed all-glass exposure system which has been previously described (Bolt el al. 1976) Desiccators of I'.sS | volume served us exposure cages: they contained 135 g soda lime (Dragersoih. Drager, l.ubcck. I-RG). Exposures were extended to 4S-5llh (Ilallier cl al. 1981) and were started bv injection of the Calculated amount of gaseous or Inpiid haiogenated hydrocarbon. Control experiments (no compound injected) were always run jsarallel as jirevnuisly described (Fiber el al. 197.8). During the experiments the concentrations ol the individual xenobiolic' in the gas phase of the svstem decreased, due to metabolism by the animals (see Fiber and Bolt 1979). In general, the concentrations in the gas phase were kept within the limits indicated in fable I by repealed dose injections, and in this range apparent zero-order declines were observed, indicative ol a constant metabolic turnover at conditions of saturation (t) (Fiber ami Boll 1979. 1981). 1 his was not the Case with chloroform and with n-hexane were a relatively fast lirst order decline was noted. Gas Chromaingruplty, The decline of atmospheric concentration of hulocihylene within the system as well tis the course of acetone concentration was determined at appropriate intervals by gas chromatography, as described previously (Fiber ct al. 1978: Fiber and Bolt 1980). Infusion of Fiuoroacciie Acid or Cliloroucctic Acid. "lo answer the question whether fluoro- or chloroacetic acid as metabolites of some haiogenated hydrocarbons contributed to acetone formation, infusion experiments were carried out. Sodium lluoro.icet.de or chloroaceiale was R&s 024298 t-:' l;v; f> in ultimate consequence .5 tosolic coenzymc A by jpoxidcs. This idea was SK* i nyl chloride metabolites I nsklcrations (Schoental c > \ he observed acetonemia ( c or disprove the above 2'| and C compounds of >: logical behaviours as to y (Boll et al. 1976) as an "i ns have been published )ynamit-Nobel AG, Troisdorf hnsed from Aldrich Europe, dichloronicihtinc from Merck My indicated (Filler and Bolt purity. When necessary, they : 99%. During controlling the is chromatograms indicative of f ISO g were used, Usually two pounds in the closed nil-glass >) Desiccators of ft.38 1 volume -orb, Dragcr, Lubcck, FRG). re siartcd hy injection of the 'ii. Control experiments (no 'Cd (Riser et al. 1978). .il'iotics in the gas phase of the id Bolt 1`17'J). In general, the d in Table I by repeated dose :rved. indicative of a constant : [919. mi). This was not the t order decline was noted. uloethylene within the system t appropriate intervals by gas ; and Bolt lostl). - question whether fluoro- or "ms contributed to acetone 'acetate or chloroaeetate was dissolved in 0.9% saline and infused into the tail vein of a rat over the duration of the experiment. The infusion rates in these experiments were 0.45 ml-h and as specified in the legend of Fig. 3. In these experiments the animals inside the desiccators were placed into restriction chambers. Results Time Course of Acetone Concentration in the System in order to increase the sensitivity of detection of acetone in the experimental system we have extended the periods of observation from 25 h (Filscr and Boll 19,SO) to about 50 h. As in the previous publication (Filscr and Boll I9H0) wc applied the halogcnatod compounds (except chloroform and n-hexane) at concentrations which assured a constant zero-order metabolism (l/,,1JV) throughout the entire experiment. I'lic extension of the observation period also permitted a better description of the time course of the acetone concentration curves. Figure 1 gives three representative examples. Whilst control animals (no xenobiotic applied) exhaled only minimal amounts of acetone, the presence of halogenated hydrocarbons sucit as vinylidene fluoride (VF2). vinyl chloride (VCI) or carbon tetrachloride, after an initial lag period which hits already been described (Filser el al. 197S), led to a significant increase in acetone exhalation. The type of the curves in Fit:. 1 suggests that the increase in atmospheric acetone in the closed exposure r ZOOISO- 37 Do CO O (O N> <0 <0 |*iK, 1. Time course of acetone concentration m the gas phase of the closed exposure system occupied h\ two rats, in presence or absence (controls) o| viinlidcnc fluoride (VF;). vinyl chloride (VCI) or carbon tetrachloride (CQj). Mean vjlues of three independent experiments SD arc given: the solid lines show the liiunes by an exponential function, as indicated in the text. The ranges of exposure concentrations arc included in Table 1 W$W'*tv-iw a*ti'.,. ;., ##* M'f'fe I|*|#||^*.\;1 V"n u;. i;6v'; 110 J. G. Filscr ct al. . chamber is not linear over the entire period of about 50 h as it was initially (Filscr ct al. 1978) supposed. In fact, all the experimental curves (Fig. 1) could be rated by the exponential saturation function y = yiag + (y* - yig) 0 - e"Ml',|Je)] - with: y =s acetone concentration in chamber, y* = theoretical maximal value for v at t * *. t,ag = initial period before beginning of the exponential section of the curve (~ 15 h; broken lines in Fig. 1). yklg = corresponding y values. k - first order rate constant of the underlying kinetic process. Curve fittings were done by use of log regression program applying the method of the least squares. The vx values thus obtained are incorporated in Table 1. For all curve fittings the coefficient of correlation r was higher than 0.9S. This was not the case when linear regression analyses were applied. KtoTs4;' US' Table 1. Exhalation of acetone by rats under exposure to different xemibioties. Closed exposure system as described in Materials and Methods. The atmospheric acetone concentrations determined after AH h and the theoretical maximal concentrations of acetone are given Compounds Range of exposure (ppm) after (he initial equilibration phase1 Acetone concentrations in the system afler Jfi hh (ppm) Acetone )V (ppm) Vinvl chloride 1,530- 5(H) 105 15 200 f&i . ,* iWf+et^-i'.s-fCj,|i'. . K'- Vinvl bromide Vinyl fluoride Vinvlivlene lluoride ri.vl.l-DiehlOroelhvlenc trims- 1.2-Dichlorocih\Icnc UUi- I5U 2.000-1.2511 s33- suo 3(0- 10(1 3.3Uo-3.luo tS-j r 10 135 15 io4 + y 205 20 |V5 M 135 200 350 500 320 'tel Trichloiooihvk-nc 6,(>(HJ --2.000 3X = 5 3SJ I'erehloroclhylene 42U- 2uu yj - io KKi Methylene chloride 1.21)11- 2(Ki Ml 6 120 m Chloroform l.uuu- 100' 33 10 ft? Curhon tetrachloride 1,000- 300 66 6 00 1, l. 1 -Ti ichlurocihunc 1.000' 4 2 1, l 2-Trichioro<Mhanc Star-- 2o<) 65 - 5 65J tt-l lexane 1.400- ID0` " ife-; safwmsy?< '> Within these limits an apparent zi'ru-nuL'r decline of concentrations was observed indicative of saturation ol metabolic capacities (see Tiber and lioli 1079). Only ihlorufurin and ii-Iicmiiic showed apparent finl-ortler kinetics; the rale of metabolic elimination of chloroform decreased afler the first 24 h of exposure, probably due to action of reactive metabolites on the enzymes of biotransformalion. The metabolic rate of 11.1 -irtchlttroiulhuu' was below the limit ol detection. x SO: three independent determinations, each witli two rats See text for explanation Linear increase up to 50 It, hence no v. can be given fi& s 024300 ri 41 EsVi* / fe1; . egg** sscist:v": x * i<-1,1, -V v, o^jv'lj' 4.- I. - J. 0. Filscret al. i as it was initially (Filser :s(Fig. 1) could befitted ial section of the curve : process. i am applying the method ncorporated in Table I. | s higher than 0.98. This re applied. tiobiotics. Closed exposure concentrations determined f J_I1 given nc M urations svstem IS hb Acetone yr (ppm) K- 15 200 It) 135 15 200 y 350 20 5(H) u 326 5 38 10 106 6 120 to 65 fi yo 2- 5 6511 3" ms was observed indicative of 'nly chloroform and n-hexane jtion of chloroform decreased metabolites on the enzymes of it was below the limit of t1 Acetone Exhalation and Xcnobiotics -i Comparison of Different Halo^enaied Hydrocarbons 111 A series of different halogenatcd Q and C2 compounds was compared as to the ability to induce acetone exhalation. The results are comprised in Table 1 which gives the acetone concentrations observed in the experimental system after 48 h as well as the theoretical y, concentrations, according lo the above calculations. Two compounds were especially included in this investigation which, according to the present knowledge, arc not biotransformed to reactive intermediates, i.c., n-hexane and l,! ,1-trichloroethane (methyl chloroform). Both compounds have a low inhalational toxicity (see Discussion section), and both compounds do not lead to an increased acetone exhalation. Figure 2 demonstrates the experimental data obtained with the two isomers 1,1,1-trichloro- and 1,1,2-trichlorocthanc. Whereas a steady and consistent rise in acetone concentrations is evoked by 1,1.2-trichlorocthane, 1,1,1-trichloroctlianc produces only an transient initial increase which later returns to values of untreated controls (compare with Fig. 1). The latter curve type was also observed with n-hexane (curve not shown); probably this transient rise is related to a more general effect such as stress when the animals are brought into the high unpleasant concentrations of a volatile xcnobiotic. Effects of Fhtoroacetatc and Chloroacetate To test the hypothesis that, in the case of halogenatcd cthylcnes which are mctabolically converted to fluoroacctate or chloroacetate, these two metabolites acetone 200-i 150- 10050- 1,1.2- tr*t .0 1.1.1 -1 ncMorof ihoo* 1 0 10 20 30 40 50h Fig. 2. Tiuu; course of acetone conccmration in the gas phase of the closed exposure system occupied by two rats, in presence of 1.1,2-triehlorocthanc (three independent experiments, x SD) or l.l.l-trichloroethunc (mean of two independent experiments). The ranges of exposure are included in Table 1 ' j y^> 112 J. G. Filscr ct al. /^-i could be active in eliciting acetone production, we performed infusion experiments with both compounds. . The routes of metabolism of vinylidene fluoride, one of the most active compounds in increasing acetone exhalation, are not known so far. However, there is experimental data (Bolt et al. 1979) that points to an interaction of vinylidene fluoride with hepatic microsomal cytochrome l'*45(). By analogy to vinylidene chloride (Bonsc ct al. 1975) it may be assumed that vinylidene fluoride is transformed to fluoroacctaie. Because thc.V'm;,, for metabolism of vinylidene fluoride in the rat is 1.1 umol x h-1 x kg-1 (Filscr and Boll 1979). we infused fluoroacctaie at even this rate. The infusion rate of chloroacetate which is much less toxic than fluoroacetate (Jaeger 1977) was related to the rate of metabolism of vinyl chloride. As the Kma, for metabolism of vinyl chloride in the rat is 1 111 umol x h-1 x kg-1 (Filscr and Boll 1979) and as it is now well established that half of the amount of vinyl chloride initially transformed by rats to the epoxide ehlorooxirane is further metabolized via chloroacetate to thiodiglyeolie acid (Muller et al. I9S0). we infused chloroacetate at a rate of 55 pmol x h"1 x kgH. The results of these experiments are given in Fig. 3; this figure compares the concentrations of acetone in the system in presence of vinylidene fluoride (see also Fig. 1) witlt the concentrations of acetone in the infusion experiments with chloroacetate. fluoroacctaie, or saline. Both haloacetates elicit increase of acetone exhalation. But a comparison with vinylidene fluoride (Fig. 3) shows that, even if all the metabolized vinylidene fluoride were indeed metabolized to or via fluoroacetate, this would not quantitatively account for the entire amount of acetone production undei stimulation with vinylidene fluoride. acetone 20- / / / // 10s- 0 I* 1 "--------- 1--------------- 1----------------1--------------- r 0 2 i. 6 8 Fir. 3. Tunc course (l()h) of uceione concentration m the rus phase of the dosed system on: (-*-) exposure to vindidcne fluoride as in Fie. 1: {O-O-Qj infusion of 55 (mint x h"1 x kg'1 chloroacetale: infusion of 1.1 pmol x h 1 x kc'1 lluoroacctjte; (A-A-A) infusion uf saline (control experiment) J. G. Filsor ct ill. wc performed infusion . one of the most active known so fur. However, 'ints to un interaction of me P-450. By analogy to assumed that vinylidenc for metabolism of Filscrund Bolt 1979), we s toxic than fluoroucctatc inyl chloride. As the K,,,.,, x h~' x kg"' (Filser and f of the amount of vinyl chlorooxirane is further (Muller ct al. 1980), we g-`- : this figure compares the ivlidcne fluoride (sec on experiments with elates elicit increase of - fluoride (Fig. 3) shows re indeed metabolized to mt lor the entire amount lene fluoride. VF, CH.Ci -tOOu CH,F -C00II )h UI-.0 of the dosed system on: 0-0-0) imIiiskim of >1 x h1' x ks'1 Hiioroaceuue. Acetone Exhalation and Xcnuhioiics Discussion The experimental data (Fig. 3) show that both fluoroacetatc and chlorottceuue increase acetone exhalation. This is consistent with the findings of Jaeger (1977) and Jaeger ct al. (1977) that chloroacetate. not only fluoroucctatc, is an effective inhibitor of enzymes of the citric acid cycle. Such an inhibition would lead to increases in mitochondrial acetyl-coenzvmc A and hence in ketone body formation. This should be viewed along with literature data that dichlorouccuuc in rat tissues in vitro (McAllister et al. 1973). in rats in vivo (Blackshear ct al. 1974), and in man (Staepoole et al. 197tS), inc.-uscs ketone body concentrations. A similar effect of trichloroacetate is not known. It is, therefore, suggested that those halogenated hydrocarbons which are metabolically converted to a mono- or di-haloacetate should increase acetone production. Table 2 compares the effect of the various compounds examined on acetone production (first column) with the (proven or anticipated) formation of haloacctic acids as metabolites (second tolumn). It was anticipated that lluorinaied or brominated ethvlenes. the metabolic routes of which are not yet known, behave similarly as their chlorinated analogs (see square brackets in Table 2)- It is especially evident from Table 2 that those compounds with the greatest effects on acetone production (marked + + ) lead also to formation of haloacctic acids which could contribute to this metabolic effect. Table 2 also compiles the presently available data either demonstrating or suggesting a formation of reactive metabolites Irom the compounds under investigation. Proven covalent binding of metabolites to protein structures was taken as the most suitable parameter to demonstrate reactive metabolite formation. Because in experiments in vivo the possibility of incorporation ol Cj and Cs fragments into proteins, via pathways of intermediary metabolism, is sometimes difficult to rule out preference was given to in vitro work with hepatic microsomes as metabolizing -ystem; therelore. citations of both in sitro and in vivo daia tire included in Tunic 2. The halogenated eihylcno. which, according to current theories, are biotranslormed through epoxides iBon.-e et al. 1975: Bouse and 1 lenschler 197f>; I lenschler and Bouse 1979) can reasonably be anticipated to show at least some covalent metabolite binding to proteins. Also the three chloromethanes examined (meihvlenc chloride, chloroform, carbon tetrachloride) are reported to be. in part, biotranslormed to covalently protein-bound metabolites. Ihcse latter compounds which obviously ate not irnnxloimed to haloacctic acids, also exhibit an effect on acetone production. This lends considerable support to the llieorv that reactive metabolites (probably via binding to the sulfhydry! ot coenzvme A; Bolt et al. 1981) lead to metabolic ellects. that cause acetone production. No effect on acetone production was expected Irom n-hexane which is metabolized via 2-hexanol. and from 1,1,1-trichloroethane (methyl chlorotorm) which is metabolized, to a very low degree only, to triehloroethanol and trichloroacetic acid whilst it is nearly completely exhaled in an unmetabolized R&S 024303 % ps^ Table 2. Compilation of acetone production data (Table I) and metabolic characteristics of the compounds investigated - ] hlocth) lencs Vm)l chloride Vimlidene chloride Viitjl bromide Vinyl fluoride Vi11 \ lute11c fluoride rb-U-Dichloiociliylene tnm s- i ,2- 1) i e liloroc t livie n e Trichloroethylene 1'ere Id 0 root b; leoe Ekilomctlumc* Meihvlcnc chloride Chloroform Carbon tetraehloride lkiloeibanes 1, M `Tridiloroei h ;i ne l .1.2-Trichlorocthane Acetone production, see Table 1 + ; >v < -00 ppm + +: ym g 200 ppm negative ++ si + ++ ++ ++ + + + + + - + Formation of haloacetic acids (ftonsc ct at. 1975; Bonse and llensehler 1976; Hcnscliler and Bonse 1979) Formation of reactive metabolites and first demonstration l: evidence in vitro - . 2: evidence in vivo -- - 3: indVi're-ct evidence a- _ , ,1 ,1..^^.;^:-- * ' -5* -- * *:!,*- Odoroaceiic acid Chloroacclic acid |E)romoacelie ack!| (Fluoroacetic acid] [Fluornacetie acid] Dieh loroacetic acid Dichluroucelic acid Trichloroacetic acid Trichloroacetic acid 1; Kappus el al. 1975 2: Jaeger et al. 1977; McKenna ct al. 1975 l: Holt et al. 1975 3: Conolty cl al. 197S1 3; Conolly et al. 197S1; Doll el al. 1951a* 3; Stbckle et al. 1979h 3: House et :d. 1975c 3: Douse et al. 1975c l: Van Diiurcn and Danerjee t976 2: Uehleke and I'oplauski-Taharctli 1977 1; Holt and Link 19S0 2; l'egg et al. 1979 1: Anders et al. 1977 - l, 2: Uehleke and Werner 1975 - 1. 2: Uehleke and Werner 1975 Trichloroacetic acid traces (lkeda and Ohlsuji 1972) Chloroaeelic acid (VHner 1971) No evidence No e\idcncc n-llexane - - No evidence " I lepa lotosicily in rats after Aroclor i 254 prcireatmenl: h Formation of pre neoplastic hepatic foci in newborn tats; c Formation of eposide Miggesiet: J Animals died because of the acute to s icily of sitiylidene chloride Square brackets; hypothec metabolite, by analogy to the chlorinated analogs / *?? D TI Jl mtzo S9d <W" F5-n.- FG3? 7c73 D 15 u o X. oC o o G "a '5 S state; this has been demonstrated in animals (Ikeda and Ohtsuji 1972) and in man (Seki et ul. 1975). On the other hand. 1,1,2-triehloroethane which is more toxic than its isomer (Klaasen and l'laa 1969) is easily converted in the organism into chloroacetic acid (Yllner 1971) and hence was expected to load to some acetone production. These expectations were entirelv consistent with the experimental outcome (Table 1 and 2. Tig. 2). ' The present data on halogenated Ci and C; compoumls are in agreement with the two hypotheses that mono- and di-haloacelates and, in general, metabolites reactive with SH-groups induce acetone production in vivo. This effect should not be limited to halogenated xenobioiics. and \ve have already reported that dilhiocarb. ;m electronegative Sll-reagent. and pyra/.ol lead to significant acetone production (1-ilser and Holt PASO). Current studies tire designed to prove the biochemical mechanisms discussed .above. . ; \ j ,? 'j ; j ; ! \ t R&S 024305 References Anders MW. (Cubic VL. Ahmed All (1977) Metabolism of halogenated methanes and macromolccular bjndme J iiimmn Pathol Toxkol 1:117-124 Ulaekshear PJ, I Iollowa\ PA 11, Alhem KCiMM (1974 f The metabolic effects of sodium dichluroacetaie in the star\od rat Hioehem J I42.279-2N(i Holt HM, Link H (PASH) /_ur Toxikoloeie uni I'crchlorathHcn. Verb Dlsch Ges Arbeilsmed 2U: 4(13-470 Holt 1IM. Knppus 1t. Htielner A, Hull W (197A) Disposition of 1.2-|4C*xinyl chloride m the rat. Arch Toxicol 35: 153- Ih2 Holt 1 IM. Knppus IL Kuufmann R, Appel KL. liuchter A, Holt \V (197b) Metabolism of lJC-vinyl chloride u\ vitro and in \i\o. INSPRM Symposia Series 53: IARC* Sci Paid I3M5I --H4 Holt HM, PiKer JG. Hinderer KK (I97N) Rat li\er microsumal uptake and irreversible protein himliny of l.2-,4C-\tnyl bromide, loxieol Appl Pharmacol 44:4SI-- 4X9 Holt 1 IM, Pilser JO. 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Acta Pharmacol loxicol 30: 24S-256 Received August 27, I9SI &pMWpM R&S 024306