Document e1Mvrm8G3L3dgE5VGg4y2L2KG

I <V/>tn/rAf 19M All nihil rtien td r TOXICITY OF CHLORINATED BIPHENYLS Lawrence Fishbrin National Center for Toxicological Research, Jefferson, Arkansas *gg8g Despite the fact that polychlorinated biphenyls (PCBs) have been available commer cially Tor 40 years, it is only within the last 5 years that (hey have been recognized to be of environmental and potential toxicologic concern. PCUs are produced by a comparatively small number of manufacturers in the USA, France, Germany, and Japan and marketed under a number of commerical trade names, e.g. Aroclor, Clophen, Fhenoclor, and Kancctor. The series of Aroclors (Monsanto) are marketed under various numbers and consist of mixtures of chlorinated biphenyls and terphenyls. The first two digits represent the molecular type: 12-chlorinated biphenyls; 25 and 44-blends of chlori nated biphenyls and chlorinated terphenyls (75% biphenyl and 60% biphenyl, respectively); 54-chloririalcd terphenyls. The last two digits give the weight percent of chlorine, e.g. Aroclor 1242 is a chlorinated biphenyl containing 42% chlorine. The PCBs have been employed in a broad spectrum of applications because of their chemical stability, low volatility, high dielectric content, nonflammability, and general compalabilily with chlorinated hydrocarbons. The major areas of utility include; heat exchanger and dielectric fluids, hydraulic and lubricating fluids, plasti cizers for plastics and coatings, ingredients of caulking compounds, printing inks, paints, adhesives, and carbonless duplicating paper, (lame retardants, and extender for pesticides. The rates and routes or transport of the PCBs in the environment (l). and their accumulation in ecosystem (2-16), have been cited. Salient features of the chemical (3. 4, 7, 1!, 14-17), analytical (3-18), biological (3, 7, 9, 14-20. 28. 30-J8), aspects of the PCBs as well as their occurrence in human diets (2-4, 14, 15, 39-42), and tissue (14-16, 33-38, 43-47), have all been reported. The major objective of (his review is to highlight the status of the toxicologic, carcinogenic, teratogenic, and mutagenic aspects of the I'CDs (hat are or greatest relevance to man. Compared to the chlorinated hydrocarbon pesticides, definitive aspects of acute, subacute, and chronic toxicity still remain rather poorly known. The toxicological 0 ?{ i , , i ,11>; c .r *, i '! * t1:* .,..r... wh K IW l; .ii : r .At- 905824 charactcri/nlioii of l'CHs is confounded by the fact that the commercial products arc mixtures of isomers, and Mendicant traces or chlorinated dibenzofurans and naphthalenes lias e been found in scscral preparations (eg. Cloplicn A-60 ami l'lieiu*clor Dp-6) (48) ANIMAL lO M C n V Parly studies of acme oral, dermal, and vapor pressure of the PClis have involved in many eases mixtures or compounds of undefined specifications and hence have been rather dilfienlt to micrprct unambigmisly. ,t. Acm e ami Subacute 7 a \id ty Table 1 summarizes measurements of the oral and dermal toxicity of seven Aroclnr mixtures to rats and rabbits respectively, and indicates that the PCBs are of a toworder of toxicity when administered as a single dose. These results suggest that while the oral ioxicily to rais decreases with increasing chlorination, there is no apparent trend or toxicity with chlorination in the data for rabbits. Miller (49), studied the toxicity of a PCH mixture ei|nivalciil to Aroclnr 1242 and indicated that the guinea pig was the most sensitive of the three species, followed by the rabbit and the rat in that order. `Iable t toxicity of Afoeloix* r :i im * in : in * i> o i.v * : C f.N 4.It. 5 m i: U t.it _Kf* i 1 I I , ! kr PIMI 4 '** W.MI ||l * H * r u tti a t1* | | iu n h IlS 'llN ^ If. Ill HI1 MM.imi11 i r x i 1 M l ' .1 Ml | i tur i r m > ji* w *iJ -pm j f .'i.ii'- i .*i. ii, ` * Ji.il*' .1-M II4' ,'INMI* i , v > * I .V I * - jimm** < ..11 m i1. * .Kim* . 1r.ti1 * JIHII1' < lll.ll 1 i n ^ 1 I. Hr l'o ri un (hr 1 h r tu D ln jti.l |.-M s--h .yx ,.t l', lx j s liu t h iU il 'A llu no M t W j i ' ^ 11111,-11 in i o n i >.|| A il.......o l r r n l j s U ( .M iH .m f t , ..|l ll-l lll.-i n i lu n e 1. V >711 IMO Sill Analogously with the eliloiinatcd hydrocarbon pesticides the most important cHeels arc long-range sublclhal elfecls. Aroclor 1254 at 1000 ppm in the diet was Taial to 'f male rats in 4J days and it was reported by Tucker & Crabtree (50) that a total intake of 500-2000 mg/kg was the lethal level under these conditions. The single-dose oral t n v1 for Aroclor 1260 and 1254 in rats is considerably higher (Table l), lienee the lethal tiled appears in be of a highly cumulative nature. Uchfeld el al (51) studied the vuhaeute toxicity of Aroclor 1248 m 10-day-old chickens. The mortality after 25 days feeding at 50, 40, JO, and 10 ppm in the diet was 16/JO, 4/20. I/JO. and 0/10 respectively. Only 2-4 out of 10 chicks survived on diets containing 100 and 150 ppm. Kolianawa cl al (52) found Karmachlor-400 j ('"48Ci chlorination) to be fatal to 10/10 chicks within 8 days at a concentration , of 300 ppm, while at 100 ppm there were no mortalities in 20 days. It is important `i to note that different batches or sources of PCBs of similar degrees of chlorination ' appear to vary as to potency, as reported by Vos & Kocman (S3) in their studies in chickens with special reference to porphyria, edema formation, liver necrosis, and j tissue residues. Aroelor 1260 caused only 15% mortality in chicks after 8 weeks, with an average time of death or approximately 3 weeks. The greater toxicity of the j latter preparation was attributed to the presence of trace amounts of chlorinated ! dibenzofurans (probably Ictrachloro- and pentachlorodibenzofuran) (48). I Table 2 depicts pathologic changes induced by PCD, and illustrates some inlercstI ing differences between mammals and birds. For example, the most sinking findings in mammals arc alterations to the liver, whereas fluid in the pericardial sac, kidney I damage, and reduced spleen arc found in birds. PCU-induced death in rats, rabbits, | and guinea pigs is accompanied by liver lesions, including fatty infiltration, cenj Irulnhulnr atrophy necrosis (49, 52), and in the case of rats, by hyaline degeneration, j Except for chloracnc-like lesions occurring at the point of skin injection or mirador1 mal injection, other organs in these species are not prominently alTected. In birds, i the most consistently observed lesions are hydropericardium and ascites as seen in the chicken (52-55). Japanese Quail (52), and bob whiles (56), Other lesions in birds experimentally poisoned with PCDs include kidney damage (52-54), liver damage (52, 54), enteritis and intestina] hemorrhages (54), subcutaneous edema (52, 55), and dermatitis (5J).' Nishizumi (57) studied the cfTccts on mouse and monkey liver of chlorinated biphenyls [48% chlorine, equivalent to three to four atoms of chlorine per molecule, with a trace (0.01% of naphthalenes]. Groups of 30 female mice were given a dosage level of 0.2 ml rice bran oil containing 1600 ppm or 0.5% PCD in olive oil by stomach tube each day for 4-26 weeks resulting in marked liver enlargement. (Light microscopy revealed only slight liver changes but electron microscopy disclosed marked alterations in the liver cells.) A similar study with 8 monkeys (5 cynomolgus and 3 squirrel) given clilorinaled biphenyls in dosage levels of 1.4--1.6 mg/day in Iheir diet Tor 40-48 days showed both liver cell enlargement and fatly degeneration. The major abnormality reported for (he administration of chlorinated biphenyls to mice ami monkeys was an increase in the smooth endoplasmic reticulum in the ver cells The administration of high doses of Aroelor 1242 to rats by oral intubation produced diarrhea, chromodacryorrhea, loss o body weight, unusual stance and gait; lack of response to pain stimuli and central nervous system depression appar ently contributed to each fatality. Hislopathological changes appeared only in the liver and kidneys as foci of sudanophilic vacuolation (58). Rats given 100 mg Aroelor 1242/kg every other day for 3 weeks showed similar hislopathological changes but no overt signs of toxicity (58). A single 100 mg/kg ip injection increased rat liver weight, total hepatic cytochrome P450, and cyto chrome hj levels. The hepatic microsomal enzyme activity remained elevated 10 I > t' . i ( t u i t i l i . ih )t i m i l i t i i i l I n |* i ttv 1li iM iirni \nim l 1-rr k iJh * 'llllilC r*( || ,)..) . r.'t u if l i ; ( u l . t u l t r j P*f M ii H ilM ^ M l.lld j..|h li |lt! iii 11 |pl't|r* IvM n e -l.-i *ir HI .1 t l t *1*1*1 1 mi n lu lh n..*m il rc flt tAtttrttA riti*inrum S< /wi/rwtf|/* th ififn IH (tri K r/ru ir* Ithi^r* j Mc 1 lunpr* Itlin w h . A p j m k j i *h>*4`i) n .1fi.*irnrt1i) th jn ffi tiiifr. t' ( im i m r d iiv l*vf (. J l M I M . 1 II 4 jtlIKI il* 1 i-H* *+}rh liv tini r u m ilr < p rrtrn t M eli dtrd vditti Ir llc f m r l i r i j l l 'H .i * d ui* in i t ip l>' ( u i(*nltii 1*' ili M il ,*V Mi A HAI pp iil eli d i r i |e f i' l L Se*l>MI M4 I 1 n in i* n i 1 11 r t | h l 1! M*4M*I> I t r r r n u m id i *>1 In jlm r f |.li1f iti i i V |- h n n St i l i l i ilinl fnnnr n i'n itiiriii h iU 'irf m rifl'l iM iif o i't Uh UH i r ,11(111' 1 liln-im r u n i* n i \ i i k | i 4 i ; 1 . i:v i; lln m rii f t jl il* * 1 S i.ft f i i l i l l t l i x i p p l i i tri A tri il** pjin* in tt^rl 4m ppii * In 1 JHNI p p in Eli tlt il u i ;* :i .'m i a 4 m i ppm in rr"1>n<li | m| Al , | n IMI I 1*1 1 Im i rii |'lat r n lirtij'jlrif I iiul> i ; m i ; . i H Mi ppm S tire n i N itrlln l 1ttliirn l A M .U llrst |>M iU l> ri| H in u rrd Slif-hl II* i l l i 'p r i u jrd n iri) 11*Itiip f t h ittlm m M u lti.jv ih iiihuiu II* J l" p m ln f l( iilil 1 M iC unr ci 4I l i , " N oilm ur*** in i rilrn r* * il :m i pri^i r*lr*i*r liriittHilt tri*. amJ pnujViiM'fji il In* if4*<'il lim i) ni inluf \i jt HirtmKi`1 nm r`ulMiH*n M fifn ni p im irji. niU t^fiii'ni *il J d ttn jl in ,| *m j|| pievi* 1 li* i **i*n`niM U *'hs t fi irti r i tc m fn ffiin 'fii p*lr <,*>Unil p.*m r r j . d r r m H h r ni u tili jr* 1 tuli r i all^A l N>* rifili h ii^ r u j t .12 t - mI l> n in tir^lM Ini utniMi 4dii * Iti iliitir ili mp Im i Pt Il |* H b t|l||ir t'vim*').tl>d1n liit-ulii rubim i U ,'M i*n 1AI J4j|f ilh iphi m.irjvil (lljltf*) ,1 In * *b 'im i $ i* J M r'Iin i* (t(MII)sl U 1 llV ilrrcnriiliun M ifhl rudi int rt j* r4 t Ir llvafil 11k|M!! Ih 4fJ u l ]rdri|>rriijidium rhtfivd <nnwui(i ilH pMpliMu*pltA I A2 m(l III Njnf u h **npd rn lu iliiin uf ed pulpni ifaphr <if h u r pilp fiompJ I A i l Srkffi dfinrjuM itom t> |4 /tlH I f, fu il luifnpd Jl Pfrui r| j| (inni VmAK'TinjfiiMi Ini |i p r . M , t 1<<pUrn am i IhmhjvI J i, ut A tm h i Jfdt ftn m p d J | r r f u tf d U iJItT ritluf r i i ! ftuifd uftittr <*uupiJ m univi* A ll, lui, k riii tliitl in tem pii I jm | i * iihm 1>ll ih* i, unl> 1V( im irijlil) i em pii .1 m i ? iip m t u n iii.,jfffff p w p n ii Attfahi day* after n duple dose of Aroclnr 1242, suggesting that PCDs may be important in altering biological responses of mammals subjected to environmental chemical stress. Roller & ZinkI (59) compared the clinical and anatomical pathological effects produced by administering Aroclors 1221, 1242, and 1254 orally to rabbits once a week for 14 weeks. The livers in the 1254- and 1242-lrcatcd rabbits were significantly enlarged compared to the 1221-trcatcd and control animals. The earliest change was megalohepatocylosis, billowed by subcapsular midzonal necrosis. Fibrous connec tive tissue replaced the necrotic part of the lobules in the more severely affected livers. The rough endoplasmic reticulum in the livers or the 1254-lreated rabbits appeared to have been destroyed, and there was also atrophy of the uteri in the 1254 treated rabbils. Dermal toxicity studies in rabbils of technical PCD samples (hat contain an average of 60% chlorine (Phcnoclor DP6, Clophen A60, and Aroclor 1260) as well as fractions containing (etra and pentaclilorodibenzofuran have been recently de scribed by Vos'& Bcems (60). PCB-indueed skin lesions were hyperplasia and hyperkeratosis of the epidermal and follicular epithelium following application of 118 nig of the three PCDs (5 times per week for 38 days) in the back skin of adult female New Zealand rabbils. Hislopalhology of the liver included ccntrolobular degeneration, ccntrolobular liver cell atrophy, focal necrosis, and cytoplasmic hya lin degeneration. PCU-induced kidney lesions were hydropic degeneration of the convoluted tubules and tubular dilation with the presence of casts. Definitive hyper plasia and hyperkeratosis of the follicular epithelium of the ear skin were seen after the topical application of fractions of Phenoclor and Clophen (eluted from chromatographic columns with 25% diethyl ether in hexane), while the Traction from Aroclor caused a minimal hyperplasia and hyperkeratosis of the follicular epithelium. Other effects elicited by the dermal application of the PCBs included thymus atrophy and lymphopenia as well as elevated excretion of fecal copropor phyria and protoporphyria. From the response of the back skin and the liver of the rabbit to the three PCB mixtures, and from the response of the car to the 25% diethyl ether-hexane fractions it was concluded that there were definite quantitative differences in toxicity, at least between the samples used in the above study (60) and prior studies (48). The extent to which these samples are representative of (he normal commercial output has not been established and emphasizes the difficulty in the evaluation of toxicity data of PCDs in which the samples may differ in.the amount and nature of toxic impurities. Vos & Deems (60) also raised the possibility that since PCD is a porphyrogenic chemical, the skin lesions in man due to PCB may be caused by a combination of chloracnc and acquired porphyria cutanea tarda. Vos & Nolcnboom-Ram (61) compared the toxicity of Aroclor 1260 with a single isomer l A S ^ '^ '^ '-hexachlorobiphenyl in New Zealand rabbits. Dermal applica tions of a total 120 mg Aroclor 1260 (5 fimes/wk for 28 days) resulted in early macroscopic skin lesions. The lesions in a 2,4,5,2',4l,5,-hexachlorobiphenyl group of rabbils treated similarly appeared later and were less severe. Hyperplasia and hyper keratosis of the follicular and epidermal epithelium were more severe in the Aroclor I" ! 1 group I'ldianced loer weights were found in both lest groups, Liver injury, as judged h) light microscopic lesions mid elevated serum transaminase levels, was somewhat more set ere m the hcxachiorabiphenyl group. Light mieroseopic findings included sulvapsul.ir necrosis, zonal necrosis, hydroscopic degeneration as ell as peripheral ami perinuclear shift of cell organelles, and focal cytoplasmic hyalin degeneration. In electron microscopy the shift was due to a proliferation of smooth surfaced iiieml'rmies of the endoplasmic reticulum (SLR) resulting in a displacement of rough surfaced membranes (KI:R). From (lie obseried ncnclikc lesions, both from the PCIJ mixture and 2,4,5,2',4`, 5<-liexaeldorobipheuyl, mid assuming that the hcxachhmihiphcnyl is free from con tamination with chlorinated diben/ofnran, we can conclude that this particular compound of the mixture I'Cll has a slight acncgenic action of itself. The major acnegenic action of crude I't'H mixtures conies from chlorinated dibenzofurans and hepatic prophyria comes only from FCli itself. It is important also to stress the toxic nature of the polychlorodibenzofurans. For example, Iri- mid Iclrachlnrodibciizofurmi in a single oral dose of 0.5-1.0 mg/kg caused severe and often lethal liver necrosis in rabbits (62). The related compound 2,.),7,8-(etrachlorodihen/o-/i-dioxin caused a lethal liver necrosis in the rabbit after a single oral dose of 0 05 mg/kg, mid when applied to the ear again in a dose 10 limes lower limit (hat found to be dicelive in the case of chlorinated dibeniofuran, resulted in chluracne, Vos & co-workers (48) calculated a maximum dose/eggof 0.2 pg pcntachlorodibenzofuran (obtained from Clophcn A60), that caused 100% em bryonic mortality when injected into the air cell of chicken eggs. The analogous elfeel was obtained with 0.05 jrg hexachlorodibcnzo-/-dioxin (63). The relationship between the toxic nature of l'Cli and the chick edema factor 1,2,3,7,8,9-hexachlorodibenzo-p-dioxiii lias been described by Flick and co-workers (54). b. Chronic ToMCttr The dTects of Inw-tevel feeding (1,10, and 100 ppm) of Aroclors )242, 1254, and 1260 to rats mid dogs have been reported by Kcplingcr cl al (64, 65). The only cfTcct noted in dogs after 12 mouths of feeding was with Aroclor 1260 in a reduced rate of weight gain, increased liver weights, and elevated serum alkaline phosphatase in males at 100 ppm, and u reduced rate of weight gain in females at both 10 and 100 ppm. The effects seen in rats after 15 months of feeding were elevated liver and kidney weights (noted only with Aroclor 1260). However, the feeding o f all three Aroclors led to an increase of liver weights and livcr-wcighl-Io-body-weight ratios at 24 months. Fatly degeneration, focal hyperplasia, and focal hypertrophy were also observed in some of the livers (64). Kinihrough el al (66. 67) described morphological changes in livers of male and female Sherman strain rats fed 20, 100, 500, and 1000 ppm of Aroclors 1260 and 1254 in their diet for 8 months. Light microscopic changes consisted of hypertrophy of the liver cells, inclusions in the cytoplasm, brown pigment in Kupffcr cells, lipid accumulation ami. at the higher dietary levels, adenofibrosis. Ultrastructural changes of the livers of exposed animals consisted of an increase in smooth endoplas- it i H P 'i M 1 if y . n n w wi m ** mic reticulum and a typical nutochnudiia. upiu rounded by concentric membranes. The epithelial component of adenofibrosis consisted of goblet cells and cells that resembled the epithelium that lines the bile duds. In general, the effect of Aroclor 1254 on the liver was more pronounced than that of Aroclor 1260. Adcnofibrosis was round in: (a) 1/10 males and 6/10 females at the dosage level of 100 parts per million Aroclor 1254 in the diet for about 8 months; (b) in 1/10 female rats at 100 parts per million Aroclor 1260 in (he diet for about 8 months; and (c) in several male rats at 1000 parts per million Aroclor 1260 in the diet for 8 months (none at 500 parts per million). The findings of Kimbrough et al in the above studies (66,67), suggesting that the mammalian toxicity decreases as the level of chlorination increases, are in agreement with the conclusions of Lichtenstein cl al (68) and Vos (26). c. Reproductive Effects A definite effect on reproduction in rats was produced by feeding 100 ppm of Aroclor 1254 (67). The first breeding was performed after 76 days on the treated diets and resulted in fewer offspring. The offspring at weaning were smaller and the survival was decreased compared to control animals. An increase in the liver weight in the Fla generation of the weanlings al a dietary level of 20 ppm Aroclor 1254 was also found. A dosage of Aroclor 1260 equivalent to 100 tng/kg/day during the 7th and 15th days of pregnancy reduced the survival and number of young. In another reproduction study in rats reported by FDA (29), Aroclors 1242,1254, and 1260 were administered at levels of I, 10, and 100 ppm in the diet. While Aroclor 1242 had n r effect on the first generation, mating indices were low in the second generation at 100 ppm. The number of pups delivered and the number surviving to weaning were reduced in both the second and third litters with Aroclor 1254. Aroclor 1260 at a level of 100 ppm increased the number of stillborn animals. No effect was observed at levels of 1 and 10 ppm. Keplingcr el al (64) reported low mating indices and decreased survival of pups , for animals receiving Aroclor 1242 at 100 ppm, and decreased survival of pups receiving Aroclor 1254 at 100 ppm. No reproductive effects were found with Aro clor 1260 at I, 10, or 100 ppm, or with Aroclor 1242 or 1254 at 1 or 10 ppm (65). These studies suggest that in mammals reproductive effects decrease with increasing chlorination. Keplingcr et al (65), also reported that chickens Ted 10 or 100 ppm of Aroclor 1242 or 100 ppm of 1234 exhibited loss of body weight, decreased thickness of egg shells, and poor hatchability of eggs. However, at 1, 10, and 100 ppm of Aroclor there were no adverse effects. While decreased hatchability was observed al 8 ppm of Aroclor 1242, there were no observed effects at 6, 4, or 2 ppm (64), Studies reported by FDA (29) indicated that decreased egg production by chick ens occurred at 100 ppm with Aroclors 1242 and 1254, but not with Aroclor 1260. Levels of 10 and 100 ppm of Aroclor 1242, and 100 ppm of Aroclor 1254 resulted in decreased eggshell thickness, which was not observed with Aroclor 1260 even at HX) ppm. The hulohahdiiy if eggs was lowered at JO and 100 ppm of Aroelor 1242 but not ,it 100 ppm of Aroelor 1254 or Aroelor 1260. Scon el ;tl found decreased egg proilnclion at dietary levels of 10 and 20 ppm of Aroelor 1254 (10 J.lf< reduction after X weeks).Uatelmhiliiy ofeggs was reduced at 10 and 20 ppm (up to 5 0 'r and 2.4'T, respectively, after 8 weeks). With a PCD let el m the eggs of 2.2 ppm. lialchnbility oi 3 and 4.5 ppm in eggs, (he hateJiahilil)' was reduced to about 5hCe of normal and almost to zero, respec tively, d, Carcinogenic. Teratogenic, and Mutagenic Effects Kimbrough (67) observed bladder cancers in two rats fed 100 ppm of Aroelor 1260 over mi 8-monih period. Nagasaki cl al (70) reported the hepatocarcinogenicjiy of Kaitcclor-500 in male dd mice fed 500 ppm of PCD. The hepatomas appeared similar to those induced by fi-isoitier of benzene hcxaehlortde (71, 72), whereas Katteclor-400 and Kaneelnr-300 had no carcinogenicity activity in the liver of mice. Kinmrn A Paha (72) described neoplastic changes in the rat liver induced by Kancclor-400. The PCI) administered (o rals in the diet at .18.5-462 ppm induced a benign neoplastic change in the liver, which appeared exclusively in the female. All the rats that ultimately ingested > 700 mg of Kancclor-400 showed hypertrophy of the liver, while pinhead to pear-sized round and pale brown flecks or modules were scattered on the,surface and on the cut surface of the liver of all female rats ingesting > 1200 mg. but on none of the male rat livers. Fatty degeneration and multiple adenomatous nodules in the liver, lung abscesses, pneumonia, splcenatropity, and intracranial abscesses were found frequently in experimental animals of huili sexes, mid depilaiion was observed in females ingesting > 600 mg of Kancclor400, Allen A Norback (73) reported the induction of hyperplasia and dysplasia of the gastric mucosa in subhuman primates (male rhesus monkeys ranging in age from 1.5-2 years ami Inning an average weight of 2.9 kg) fed a diet containing 300 ppm of Aroelor 1248 or 5000 ppm of polychlorinated triphenyl (Aroelor 5460) (PCT) for 3 months. During the course of the experiment, the animals were given access to 400 g of the experimental diet daily. Within I month, all of the PCI) fed animals and within 6 weeks, all of the l'C l' fed animals (6) had hair loss from the head, neck, and back. A progressive, generalized, subcutaneous edema, particularly of the face, was manifested as swollen eyelids ami lips, rite concentration of PCI) within the experimental diet was less than an order of magnitude greater than that occurring in random food samples sold in the United Stales and less than levels that have occurred in food products as a result of industrial accidents. The increased ccllularity, abnormal dypJastic growth pattern, and invasion orthe adjacent tissue region indicate compromised gastric function and were believed by the authors to be suggest/re of an eventual neoplastic transforma tion However, the carcinogenic potential could not be evaluated from a short-term study. McLaughlin ct al (74) reported that Aroelor 1242 gave no hatch at a level of 25 mg when injected into chicken yolk sac. Al a level of lOmg/cgg embryos were found ^ I P*1,1 m m i" I* A B 1f (W 905828 with buck deformities, edema, and growth retardation. Carlson & Duby (75) found that injection or Aroclor 1242 into chicken eggs on day 0 of incubation severely limited halchability at levels above 2,5 ppm. The 1254 and 1260 isomers were less effective in this respect, requiring 10 ppm or more. Embryonic mortality occurred during the period of organ formation, suggesting an effect on inductive mechanisms (several malformations in chicks (hat developed until day 21). The effects induced by the day 0 injection of the 1242 isomer were permanent, as growth rales were severely depressed during the 2 week period following hatching. Aroclor 1254 was found to be fclotoxic to the rabbit at amounts of 12.5 mg/kg and above as evidenced by abortions, maternal deaths, and stillborns (76). The fetolnxic effect did not appear to be dose related nor was it influenced by the period of administration. The rat did not appear to be as sensitive a species, as doses up to 100 mg/kg did not cause fetal deaths or malformations. Dead fetuses from treated animals showed no consistent skeletal abnormalties. Oral administration of 12.5-50 mg/kg/day did induce abortions and was fetopathic to rabbits when treated for the first 28 days or gestation. In a preliminary study (76) the oral administration of 50/mg/kg of Acroclor 1254 to 6 pregnant rabbits 5 days a week during their gestation period also caused abortions and fetal deaths. Pcakall cl al (77) reported that embryos from the second generation of Ring doves (Stn-ptopclh maria) fed 10 ppm Aroclor 1254 exhibited a high frequency of chromosomal aberrations and a high incidence of embryonic death. No chromosomal aberrations were observed in human lymphocyte cultures ex posed to Aroclor 1254 at 100 ppm (78), and Keplinger et al (64), employing a dominant lethal assay, reported no evidence of mutagenic effects of Aroclors. Green ct al (79) described the cytogenetic effects oi Aroclor 1242 on rat bone marrow and spermatogonial cells. Aroclor 1242 was given to albino OsborneMcndel rats as an acute dosage (PO) at 5000, 2500, and 1250 mg/kg or as a subacute regimen at 500 mg/kg and as a solution in corn oil at the other levels. The results from the bone marrow study showed no significant increases in chromosomal abnormalities or inhibition of cellular division. The study of spermatognnial cells showed significant increase in abnormalties but statistically signifi cant decreases in the number of dividing spermatogonial cells (P < 0.05). This effect was noted al 500 X 5 and 5000 X 1 dosages. It was concluded that Aroclor 1242 does not produce chromosomal abnormalities in rat bone marrow or spermatogonia but docs cause, al relatively high dosages, a decrease in the number of dividing spermatogonial cells. e. Immunosuppressive Effects An interaction or PCBs with duck hepatitis virus was found by Friend & Trainer (80). Tcn-day-nld ducklings fed Aroclor 1254 at 25, 50, and 100 ppm of PCBs for 10 days suffered no apparent clinical intoxication but when challenged with duck hepatitis virus 5 days later suffered higher mortality than ducklings not exposed to l'CU but challenged with the virus. The effect of I'CB (Clophen A-60 and Aroclor 1260) feeding at levels of 0. 10, 50, and 250 ppm on the humoral and cell-mediated immune response was described by Vos & Van Driel-Groolenhuis (81). A suppression to the humoral immunity was II I TH i i P li'inul ,u the Ml ppm lixcl 111 guinea pigs. alter stimulation 'Mill one dose ol tetanus toxoid fahmi-udsojhcd) I lie number of tetanus antitoxin-producing cells mi the stimulated popliteal lymph mules was reduced. Stress was mu considered response We !<r ilie reduced mimunulngieul responses. A hipli mortality oeeiirrcti aI Ilie 250 ppm level. Cachexia ami depletion of the lymphoid .system and liver damage were ilie most import.ml findings m these animals. The immunosuppressive aelivjiy of Aroelor 1260 (10 and 50 ppm over 8 weeks) on Ilie Immoral immune response in female albino guinea pigs was studied by Vos & Deroij (82). using tetanus toxoid as a function test of the immunological system m half the animals. Cellulose acetate electrophoresis was used to determine Ihc seven proteins, including the y-globulin level. The number of y-glubulin containing veils in the popliteal lymph nodes was determined sciniquati Ialively with the direct nuoresecni antibody technique. (Doth techniques were sensitive parameters for the iininuuosuppressive act ion of PCD iii the tetanus toxoid stimulated animals.) Vos & Deems (60) found a reduced number of white blood cells, atrophy of the cortex of Ihc thymus, and a reduction in the number of germinal centers in the spleen and lymph nodes after dermal application of high doses of I'CDs in rabbits. This suggests the possibility of an immunosuppressive action. Deeding guinea pigs 10 ppm Aroelor 1260 for 8 weeks (26) resulted in a decreased number of antibody-forming cells in the popliteal lymph nodes, after stimulation of the Immoral lymphoid system with tetanus toxoid. Vos (26) suggested that this suppression may explain the higher sensitivity o fl'CHTcd ducklings for duck hepati tis virus (80). Small spleens were noted in chickens fed I'CDs, showing atrophy of the lymphoid system (52. 53). Human Ptfccts In 1%8. an outbreak of poisoning that involved at least 1000 people occurred in Northern and Western Japan where rice bran oil was contaminated with Kancclor400. Tins t'CD contains 48CI chlorine and has as its main components 2.4,3'.4'-, 2.5.3',4'-, 2.3.5,4'* and 3,4,,V.4'-tclraehhirobiphenyl. and 2,3.5.3'.4'-pentachlorohiplieuyl 183). The disease was named " Kanvini Yusho" (34, 84). The contamina tion occurred because PCIk used as heal exchangers in the manufacturing process leaked into the oil through pin holes in the pipes. Dmcda claimed (33) that there arc an estimated 15,000 victims of Kancnii Yusho although only 1081 persons have been officially diagnosed as such. Exposure levels to the nil were calculated to approximate 15.000 mg/day. The lowest reported figures allow an estimate of a minimal positive elfccl level at 3 mg PCD per day over several months, limveser, the average doses associated with significant disease m the "Yusho" incident were much higher and were in the range of 30 mg/day (15. 28). The latency period between ingestion oi the oil and the onset of clinical signs and symptoms was estimated at 5-6 months (3). The clinical aspects associated with Yusho included: chloncnc, blindness, sys temic gastrointestinal symptoms with jaundice, edema, and abdominal pain. Cliloraene is very persist cut. with some patients showing evidence of it after 3 years. Table -- .*-- M i i i i i a i d i i k t t n A f a f l i i i i j b T i i i t f t i f a k i M lijifi/ifS ifii' A A t^ iiii 14111c J j U u j t 1. 11*1 ill p it ,m .* i i i i | i i . i n K u , ............ , 905829 Symptom Mate (%) female m Dark biown pigmentation oT nails Distinction <il ban follicles Incicased sweating at palms Acnclikc skin eruptions Red plagues on limbs lulling Pigmentatint) of skin Swelling of limbs Stiffened sole and palm Pigmented mucous mcmbianc Increased eye discharge Mypcraemia of conjunctiva Transient visual disturbance Jaundice Swelling of upper eyelids l-'celing of weakness Numbness in limbs l:evci Heating difficulties Spasm of limbs Headache Vomiting Diarrhea 83.1 64.1) 50.6 87.6 20.2 42.7 75.3 20.2 24.7 56.2 88.8 70.8 56.2 11.2 71.9 58.4 32.6 16.9 18.0 7.9 30.3 23.6 19.1 75.0 56.0 55.0 82.0 16.0 52.0 72.0 41.0 29.0 47.0 83.0 71.0 55.0 n .n 74.0 52.0 39.0 19.0 19.0 8.0 39.0 28.0 17.0 sl'.[pli(y-mne male and 100 female patients diagnosed befoie October 31, 1*1611 were examined. hl:n>m a report oi "Yusho, A Poisoning Caused by Rice Oil Contaminated witli Ctdoiobiphcnyls" (Ref. 84), 3 lists the subjective symptoms of 89 male and 100 female Yusho patients. The severity of the disease varied with age, being greatest from adolescence through 40 years (85). 'Die disorder generally cleared when exposure to the offending agent was discontinued. Newborn infants or poisoned mothers had skin discoloration due to the presence of l'CU via placental passage. (The dark skin discoloration regressed after a period of 2-5 months). Gingival hyperplasia with pigmentation was seen in several cases. Decreased birth weights were also noted, but no evidence could be obtained in regard to the possible retardation in physical and mental activities of the babies (86). The skin of stillborn infants showed hyperkeratosis and atrophy of the epidermis, and cystic dilation of the hair follicles. Residues of PCB have been found in fetal tissue (87, 88). Examination of autopsy tissues of two Yusho fatalities revealed the presence of chlorobiphenyls in all of the examined organs, especially mesenterial Tatty tissues, skin, and bone marrow (87. 89), PCBs were found with longer retention times (probably peniachlnr- mill lusher chlorinated biphenyls! in autopsy tissues, anil it was assumed that ilu-ir presence might have been responsible for the obsersed lone iliiralion of the mimieaiion symptoms. Additional detailed elirneal and experimental studies have been made regarding the cluneal feaiutes of Vnsho and concerning toxicological clfcets on laboratory atuiiials (34 37) Among (lie miscellaneous observations of biochemical and physio logical abnonnahiii's m Vnsho patients are; increased urinary 17-kelosleruid eserelion, respiratory distress with secondary infection of the upper respiratory tract, a hematological picture suggestive of acute or chronic inflammation, and elevated blood-scrum triglycerides, Chloraencgcn eHecis were reported as early as 1936, following industrial exposure to the I'CHs (32, 90-06) Approximately 10 cases of fatal intoxication involving persons ivlm handled or were exposed to chlorinated biphenyls or naphthalenes in their occupations have been described (94, 96). In all cases histological examination revealed liver fatty degeneration necrosis and cirrhosis. In contrast to the reports of industrial PCD poisoning, the outstanding difference m Viislm disease is the frequent occurrence of hyperpignienlalton of the skirt, as seen in 72G of omen and 7Jr r of men. which may be due to the differences in route of intake The Vtnho cases resulted from oral intake while industrial cases resulted from dermal exposure, l.ivcr damage (in contrast to occupational poisoning) was not marked in the Vnsho cases. Two surveys of human adipose tissue in the USA (44, 45) gave broadly similar results with means or the order 1.0 ppm PCI). Hiros et al (43). however, have reported 200 and 600 ppm of PCD in samples of human adipose tissue, and Price (44) reported that one autopsy ease contained 115-240 ppm in fat. Mean levels of PCD in human blond plasma were reported by Finklea et al (38) to be in the order of 2.0 ppb. In this study, rural Negroes had much lower levels in hlood plasma (0.35 ppb) than the overall. Rural whites had slightly higher levels (near 3.2 ppb) Interestingly, this pattern was opposite to that of E DDT, in which rural Negroes had by far the highest levels (38). Kiscbrougl>& Drodine (47) reported the mean PCD level in human milk from two cities in California to be about 60 ppb. Mean levels in human milk in Sweden and Germany were 16 ppb and 100 ppb respectively (41,46). It has been calculated that, hased on a daily milk intake of 150g/kg, breast-fed infants in California ingest some 9/jig/kg/day of l'CHs. The toxicological consequences of body burdens of PCDs arc difficult to assess at this time. g. Miscellaneous Toxicological and Biological EiTecis Aroclor 1254 was found to potentiate the toxicity of carbon tetrachloride in a manner similar to that reported for DDT (28). The studies of Grant et al (97) suggest that the liver is the main site of Aroclor 1254 metabolism, because rats with carbon tetrachloride damaged livers were unable to metabolize this mixture of chlorinated biphenyls as rapidly as rats with normal livers. Aroclor 1254 significantly increased the size of flic liver and also (he percentage or lipid in the liver. The same study revealed that the components of Aroclor 1254 with the shorter GLC retention times, 905830 presumably with the lowest chlorine cunlcni (vo;, * 1: mti.MJun.xu m ^ degree than those with the longer retention times. This effect is in agreement with the studies of Phennchlor DP6 fed to Japanese quail (99). Street and co-workers (25) studied the effects of diets of 50 ppm to 100 ppm of 10 Aroclors ranging in chlorine content, and 2l% -68% fed to rats for 15 days. Their effect on sleeping time induced by hexobarbilal, in vitro rales of aniline hydroxylation, and dcmclhyation of /Miitroanisolc. and the rale of excretion were all found to be increased with increasing chlorine content. Aroclor 1221 (50 ppm) reduced hexobarbilal sleeping lime by 11%, whereas for Aroclor 1248 and 1268 the figures were 35% and 48%, respectively. Liver weights also increased with increas ing chlorine content of the Aroclors. The storage oi dieldrin was decreased in relationship to the chlorine content. For example, with Aroclors containing 60% chlorine or more, the storage in adipose tissue was reduced to the levels found in untreated control animals. The induction of PCDs of hepatic microsomal bydroxylating enzymes has been demonstrated in the American kestrel (Peakall & Lincer 7) and pigeons (Risebrough et al 5). Villeneuve et 3! (101) studied the effects of PCD administration on microsomal enzyme activity in pregnant rabbits. The nil-effect level or Aroclor 1254 for enzyme induction in the pregnant rabbit is between 1.0 and 10 mg/kg body weight when administered for 28 days during gestation. Aroclor 1221 induced no enzyme activity in the does, fetus, or placenta, so its nil-cITect level must be considered higher than that for Aroclor 1254. Placental transfer was shown to occur for both Aroclor 1254 and 1221 but causes no changes in the biochemical physiological parameters mea sured, c.g. total amount of Vitamin A stored per liver, protein levels, aniline hy droxylase enzyme activity, serum cholesterol, no effect in reproductive processes. The drug-metabolizing enzymes aniline hydroxylase and aminopyrine-n-demethylase were both induced by 10 mg/kg Aroclor 1254. Litters! & Van Loon (100) studied enzyme induction by equimolar dietary amounts of DDT, phnobarbital, and Aroclor 1254 after 30 days of treatment. At 150 i* mole/kg of food, the PCD was far more effective than phnobarbital, and at least as effective as DDT. At 15 ju mole, phnobarbital, DDT, and Aroclor 1254 produced substrate-specific increases in enzymatic activity. (to and co-workers (102) found that the administration of PCDs (0 rabbits in creases the total lipid, trigylceride, and cholesterol content of liver and decreases the total liver phospholipid content. (The concentration of serum triglycerides was abnormally increased.) Lincer & Peakall (24) demonstrated an inductive effect on estradiol metabolism * from the administration of Aroclor 1254 and Aroclor 1262 to American kestrels. Aroclors 1221, 1232, 1242, and 1248 also have an estrogenic effect on the rat uterus, which was not shown with Aroclors of higher chlorination (22). The estrogenic activity was evaluated using the 18-hr glycogen response to the immature rat after a single subcutaneous injection. Plaionow & Funnel! (23) reported an antiandrogcnic-like effect in cockerels when Aroclor 1254 was incorporated in the diet at 250 ppm for as little as 6 weeks. Vos (26) suggested that both increased steroid metabolism as cited by Rehfeld et al (51) ami Ilie cvtmgcmc activity could be responsible for the depression o secondary Visual characteristics such as decreased development of comb and wattles noted in cockerels (2.1) Orberg el nl (2 1) described the prolongation of eslrus cycle in NMKI-strain mice given single ip ivdunnisirations of DDT (40 m/kg) and Clophen A-6U (20 rng/kg). The prolongation appeared to decrease with time, the lengths returning to normal after 3 cycles. The dice is observed probably indicated that the chlorinated hydro carbons alfecled the catabolism of steroid hormones. No changes were found in the frequences of coruitied cells after the ingestions. A prolonged eslrus cycle implies less frequent periods of sexual rcceplivity in the female and hence could cause a decline in the reproductive capacity of the animals. Ogawa (103) demonstrated neuropathy in rats following administration of PCD (0,3-0.5 inl/hg/day) for 14 or 21 days os evidenced by marked or moderately impaired motor function, decreased motor conduction velocity, and loss of large nerve fibers. Norback & Allen (104. 105) reported that ingestion of PCBs by rats for 1-5 weeks resulted in liver hypertrophy, with proliferation of the smooth surfaced membranes of the endoplasmic reticulum (SER) and formulation of large concentric membrane arrays within the cytoplasm of the hepatic cells. These concentric membrane arrays were suggested by Vos (26) as probably representing the hyalin bodies described by Dennett et a) (106) and Miller (4`>) and could have an enzymatic function similar to that associated viilli the SER (104, 105). Yap el al (107) reported that I'CDs inhibit the activity of fish ATPascs in vitro. Doth Mg'*ATJ'asc and N A f -K+-ATi\ise were inhibited in brain, kidney, and liver al concent rations as low as 0.03 ppm. An analogous effect for DDT has been cited in the above study. /i. Summary mu Ctwc/usions Despite the increasing number of mammalian toxicological investigations, aspects of tfcfhiitnt' acute, subacute, and chronic toxicity of the polychlorinated biphenyls still remain pnoilj known as regards man. The chemical and physical properties, c.g the stability, complexity, and heterogeneity of the commercial formulations per se, tile difficulty of separation and analysis as well as the non- or ill-defined nature of the materia! actually used or reported in many studies, conspire in making the evaluation of toxicity and biological data difficult. A number of the more salient biological and toxicological aspects of the PCBs are summarized in Table 4. It is possible to distinguish two actions of the PCBs on mammals, e.g. liver damage and skin lesions. Liver damage has been predominantly manifest in mice. rats, guinea pigs, rabbits, and monkeys in feeding and to a lesser extent in inhalation studies, l.iscr damage and transplacental transmission as shown m abnormal pigmcrilation and miscarriages have also been observed in the Yuslio poisonings in Japan. Skin lesions have heen observed in rabbits in dermal toxicity studies. In addition, chloracucgcnie and porphyrogenic as well as edema effects in 'many species have been caused by commcrical PCB preparations. The liver damage and skin lesions arc believed to be caused primarily by chlorinated dibenzofuran contaminants and to a minor extent by PCB itself. These contaminants are also 905831 responsible for the edema lormauun to the causative agent Tor the hepatic prophyria. In contrast to the acute toxicity, aspects of subacute and chronic toxicity appear to be nf far greater concern. In rats the acute LD#0 is of the order of 5-10 g/kg. Chronic intake nr relatively small doses of PCDs, however, has been demonstrated to have adverse clfccts in man and other vertebrates. For example, in man it has been estimated that as little as 10 mg/kg over 50 days causes chloracne. It has also been shown that toxic effects during continuous exposure at low levels may only appear after extremely prolonged intake, e.g. certain reproductive effects of Arodors 1242 and 1254 in rats were not manifest until after 15 months of prolonged intake. Although deaths from exposure, either acute or chronic, have not been clearly documented for man, aspects of the toxicity as described above coupled with increasing reports of the ubiquity or the presence of PCBs in humans (analogous to DOT and DDE) suggest further study is essential to elaborate more definitely the potential toxicity of this environmental pollutant. In this regard further toxicologi- Table 4 Some toxicological and biological effects of the PCBs 1. Acute oral LOjq in mammals varies from approximately 2-10 g/kg. (Apparent increase in mammalian toxicity with decrease in chlorine content.) 2. Induction or hyperplasia and dysplasia of gastric mucosa in subhuman primates. 3. Enlargement of the liver and vacuolar or fatly degeneration of liver cells in rats, guinea pigs, and monkeys. 4. llepalocarcinogcniciiy in mice and bladder carcinogenicity in rats. 5. Production of hydropeiicardtal edema in chickens and Japanese quail. 6. Teratogenic effect in chick embryo. 7. [Ototoxicity in rabbit. 8. Adverse reproductive effects in rats at levels of ca 100 ppm in diet. 9. Adverse reproductive effects in mink. 10. Enhanced chromosomal aberrations and cnibyonic death in ring doves. 11. Effects on halchability in chickens, Japanese quail. t S. Skin, liver, and kidney lesions in rabbits following dermal exposure. 13. Immunosuppressive effects in rabbits. 14. Chemical porphyrogcnic effects in many species. 15. Chloracncgcnic and hepaloioxic effects in man. 16. Ilyperglyceridcmic effects in man. 17. Human miscarriages, stillbirths, and transplacental transmission in abnormal pigmentation from "rice-oil disease" (Yusho). 18. Hcpaloxic, chloracncgcnic, and porphyrogcnic effects o f chlorinated dibenzofuran contaminants in several species. 19. Potentiating of toxicity (e.g. carbon tetrachloride) in rats. 21). Chloracncgcnic effects of chlorinated naphthalene contaminants in man. 21. Generally, enzyme induction increases with increase in chlorination of PCBs. 22. Induction o f hepatic hydruxylaling microsomal enzymes and increased estrogenic activity in the rat. 23. Inductive effect on estradiol metabolism and anti-androgenic eje c ts in kestrels. 24. Prolongation nf cstrus cycle in mice. 25. Inhibition of ATPascs in vitro. 1M u s u i l i in cal and lin*li*i'.u';U studies iiivnKtnp key imlivulu.il cliaracteri/ed 1'CIi isomers, mice cuniatnmuiii iltlotmilled diluu/ururaii ami iinpliiltaleiics. defutilive pharitiacokinclic ckihtnaiioiis [perhaps in primates). and mure definitive imiljpeiiic and terato logic skulk'*- should alt Help in this nmst needed assessment. I iterature Cinxt \ Nishet. I. C I . Sniolim, A. F. 1972. 24 l.mcer. J I . . Peakall, D. II. 1970. Na- 'liuti* Health Perspest. 1:21-38 une 228,78.1-84 2. Riseti rough, R W . Dclappo. II. 1972. 2?. Slreel, J. C. el al 1*169. Compararne /.it iin vi Health /V n/vvr 1:3*1-44 crfivr* n i Pi'lis unti oryanuehloriae pet ,1 Nelson. N l,|72. IVdychini muled tia Jes m tnduetion ofhep,ittc mietesti- Niphcnvls- Fnvimmncnlnl Impaci. En- uniti Rei 5:253-362 4 Jensen. S Ambili 1:12.1-31 5. Kisclitii(:l. R. tt\ et al 1968. Nature ttul etuymes Prcscnicd al An>. Chem. Soc. Mec., Neo York, Sepl. 8-12 26 Vos, J. G. 1072. Emiten. iicjUh Per- spect. 1:105-17 220 11178 1102 6 Gusiafsnn, C ti l*)70. Enitren. Sci. ftxhnel 4 814 J`l 27. Stallini!. D.. Mayct, F. C. 1972. Enuren Health l`crspi\. 1:159-69 28. Kolbye. A. C. Jr. 1971. Cutreni stetti* 7. re.ik.dl. D H. I,nicer. J L. 1970. Dioscience 211*1?* 1)4 8 llaimimiid, A. I. I*>72 Science 17?: o f lo.ueeleyieal etieet* o PCD*. PDA, Wash. DC Sepl, I & 29 29. [ltirkc, J,, Fiirhugh, O, G. 1970. Suppt. 15? tfl *1 Savane. 1' l` . Tcssan, 1. 1971. J. Enli ten Health .1? 311-.14 I, S u itis Rept, e f Chemistry <S To.i- icoloyv o f PCM*. FDA, Wash. DC Dee. I 10. Veilli, G. C . I.ee. . I". 1*170. Il'afer JO. Cook. J VV. 1970, Status Reparl on thc e w r . 4:2(>? 71 j Chenttsttv itnj Tosieoloyy o f PCBs. 11. Kcvmdds. I., M. 1*171, Rimtic Rey. . k l 'D A , Wash DC. June I 14 27 81 f JlISchwari/, I. 19.16. V. S. Pubi Health 12. Hidden. A V 1*170. Nature 228*. > < / / I't. 2:229 1220 24 f -12/Mcips, J. W., Album. J. J,, Canili. U, L. 1.1. Zuko. v. 1*171. /lull -usiron. Centani v-- 1954. J Am. McJ. A.ssec. 154 1417-18 7i iiicd/ (i 4t'4 7(1 JJ. Uinctla. G. 1972. Ambiti 1:132-44 14, Zukn. V, Cimi. 1'. M. K. 1971. l'CII 34 Kur.itsunc. M, el al 1972. Envinan. and nOn.'r imliistri.il hnlopeiiulcd hydro, carbn* m (he emireumail. Enhene* Res huid i'ftanaila Jiv/i, Rent. No, Health Petspect 1:119-28 35. Kurntsune, M. 1972. Envtron. Health Pcrspect. 1,129-36 272.2 ?4 36. Repons of lite Smdy Group Cor `*Yu- 15 Pnlycldntinnlcd lliphcnyls and (lie l:n- slio" (Clilnruliiplienyls l'oisoning). virmi meni 1*172' tnlentepail mental Task Torce on l'Cli*. Nal. feeh. lnti>. Sen Springfield. Va 1-IR1 Ib Fistihcm. 1. 1*172 f <bremaleer. 68: .14? 4Jt. 17 Cook. I W 1972. Emireu. Health Per- 1*1(i9. EtiltieU Acta Mol. 60.403533 37. l'lic Secund Repon of tbe Study fur "Yiisho" (Chlorohphenyls Pnsuning). 1971. EuktteU Acta McJ. 62:1-176 38. l inklea. J, F. et al 1971. Poiy- t/sv/. I:.l l.l ehlermateJ Dphenyi Resdue* in Hu 18 Sissons, IV. Welli. I) J. 1971, / f tn'liuti ijer. tifi 1?-.12 l'i. Hitman. J.. Ceti!. Il C . Harris, S . 1*172 :'miteti Set Peoptvt. N 4 ? 4`> 20 Ntirb.uk, l>. II.. Allen. J. K. 1972. En'tren Set /Va / w . l.T.17-49 man Plasma. Presemeli al 99|h Am, Pubi. I(calili As.soe. Mec,. Minneapo lis. Minn Oel. 11-15 39 Kolbye, A. C. 1972. Emiten. Health Perspeet. 1:83-88 40. Wcstiiti, G.. Noru. K. 1970. Vitr Ftkfa 21 Orberp. J . Johansson, N.. Kthlslnnn. J. 22:93-146 H., 1 nmlberp. C. 1972. Ambio 1: 41. Wcstit), G.. Noren. K., Aiulersson, M. 148 4*1 22 Ibnmaii. J . Cecil. 11. C. 1*170 J. Ayr. `it'll ( Vieni.18 1108 -14 2.1. I'laliinotv, N S.. Funnel), II. S. 1971. 1970. Vr Eiida 22:10-42 42. IsoiiD, N 1*J71, Critica! Neis\ 1,1 -2 43. lliros. I:. A. 1970. J.. Walker, A. Unii. Etmten. CC.o.nMtacttdi.berruryi. W Ree 89.109 Ul no/ 5:317-23 TOXICITY OF C IlLO R lN A ltu d m ------------------ 44. Price. H. A. 1972 Environ Health Per- 67. Kimbrough, R. D. 1971. Interagency spcct. 1-73-78 Meet PCBs, Dept. HEW, Wash. DC, 45. Yobs. A. R: 1972. Environ. Health Per- Aug. 3 sjw t 1:79-82 68. Lichtenstein, E. P., Schulz, K. R.. Fuh- 46. Acker, l . , Schulte, U. 1470. Nalunvis- remann, T. W, 1969, / Eicon. Entomol. xcnschaflen 57.497-500 62:761-65 47. Riscbrough, R., Ilrodine, V. 1970. Envi 69. Scott, M. L. et a) 1971. Results ofexper ronment 12.16-27 iments on the effects of PCDs on laying 48. Vos. J C. ei al 1970. Food Cosmet. hen performance. Proc. J971 Cornell Toxicol 8-625r.ll Nutrition Conf. Feed Mfrs. 56-64 _S f4 9 JM ilIcr. J. W. 1944, V. S. Pubt. Health 70. Nagasaki. H. el al 1972. Gantt 63: r K ^ K c p t . 59:1085-93 B05 50. Tucker. R. K., Crabtree, D. G. 1970. 7|. Nagasaki. H. 1971. Gann 62:431-32 Handboiik o f Toxicity o f Pesticides to 72. Kimura, N. T., Baba. T. 1973. Gann Wildlife. U. S. Dept. ofTnlcrior. Uurcau 64:103-8 of Sport Fisheries & Wildlife, Pub!. 84, 73. Allen, J. R., Norback. D. H. 972. . Wash. DC / c --r-yScicnce 179:498-99 51. Rehreid, B. M.. Bradley. R. L. Jr.. [ 74VMcLaughlin, J., Marliac, I. P., Verteil, Sunde. M. L. 1971, Poultry Sei. 50: ' -- ^ M. J., Muichler, M. K. Fitzhugh, O, G. 1090-96 1963. Toxicol. Appl. Pharmacol. 5: 52. Kohanawa. M., Sboya. S., Ogura, Y. el 760-61 al 1969. Nat. Inst. Anim. Health Quart. 75. Carlson. R. W,, Duby, R. T. 1973. Bull. 9:213-19 Environ. Contant, Toxicol 9:261- 53. Vos, 1. G., Kocman, ]. H. 1970. To*- 66 iced Appl. Pharmacol. 17:656-68 76. Villeneuve, D. C , Grant, D. L., Khera, C517`Flick, D. F.. O'Dell, A. G., Childs, V. K. 1971. Environ. Physiol 1:67-71 >ST^ A. 1965. Poultry Sei 44:1460-65 77. PcakaU, D, B,, l.inccr, J. L.. Bloom, S. C 55. McCune, E. L.. Savage. I. E.. O'Dell, B. -- L. 1962, Poultry Set. 41:295-99 E. 1972. Environ. Health Pcnpcct. I: 103-4 56. Heatli, R. G., Spann, J. W,, Kreilzer. 3. 78. Honpingarner, R.. Samuel, A., Krause, F, 1970. Effects o f Polychlorinated D. 1972. Environ. Health Pcnpcct. I: Diphenyls on Birds. Presented at XV 155-58 Congr. Enl. Ornilhol. Den Haag. Sept 79. Green, S., Palmer. K. A., Oswald, E. J. 3-7 1973. Absir. lllh Ann. Meet. Soc. Toa- 57. Nishizumi, M. 1970. Arch. Environ. icol., New York, March 18-22 Health 21:610-26 80. Friend, M,, Trainer, D. O. 1970. 58. Bruckner, J. V,, Knanna, K. L,, Cor- Science 170.1J 14-16 nish. II. 11. 1973, Toxicol. Appl. Phar- 81. Vos. J. G., Van Driel-Grnolcuhuis, L. mocol. 24:434-38 1972. Sei. Total Environ. 1:289-302 59. Koller, L. D.. Zinkt, I. G. 1973, Am. / 82. Vos. J. G,, Deroij. T. 1972. Toxicol. Pathol. 70.J6J-73 Appl Pharmacol 21:549-55 60. Vos. J. G., Deems, R. 0- 1971. Toxicol. 83. Socki, S., Tsulsui, A., Oguri, K:, Yo- Appl. Pharmacol. 19.617-33 shimura. II., Ilamana, M. 1971. 61. Vos, I. G., Nolenboom-Ram, E. 1972. Fukuoka Acta Med. 62:20-23 Toxicol. Appl. Pharmacol. 23:563-78 84. Kuralsunc. M. et al 1969. Fukuoka 62^6.1uer. II.. Schutz, K. H., Sptcgelberg, Acta Med. 60.513-32 V. 1961, Arch. Geaerbepathol. Gc*er- B3. Goli. M., Higuchi, K. 1969. Fukuoka 18:538-42 Acta Med. 60:409-31 (-63 J liEKUihotliam. G. R. el al 1968. Nature 86. Yamaguchi. A., Yoshimura, T., Kurat- 220:702-5 sune, M. 1971. Fukuoka Acta Med. 62: 64, Kcpfingcr. M. L. el al 1972. Toxicologi 17-21 cal Studies with Polychlorinated Biphe 87. Kojitna, T.. Fukumoto, H.. Makisumi, nyls. PCB Coni. Quail Roost. Conf. I. 1969. Zap. J. Legal Med. 23:415- Center, Rougemont, NC. Dec. 1971 17 65 Kcplinger, M. L., Fancher.'O. E., Ca- 88. Inagami, K-, Knea, T., Tomita, Y. laudra, J. C. 1971. Toxicol. Appl. Phar 1969. Shokuhin Etsei Gaku Zasshi 10: macol 19:402-3 312-15 66. Kimbrough, R. D,, Linder, R. E.. 89. Kikuchi, M. 0,, Mikagi, y., Ha Gaines, T. 13. 1972. Arch. Environ. shimoto, M., Kojima.T. 1971. Fukuoka Health. 25:354-64 Acta Med. 62:89-93 905832 :i |i |! Xt hwiiri/. I. I'Ofi Am J Pubt Health lb 5K 61 M > u , in / , | I 'M l / A m M id .V(\- i : : u* hi idiuarlr. t. H.irli', I-' A 1**42, i ' S Pithin' Health R,T n ,17:1747- ?0 Jones. J W . AMcn, It S 11,16 Atx'h ncm u h 'I ,*i/>//,/ .12 102;. 26 Mm. F II. J.irufc, 0 K. 1*16 Pnv. A x\ /ixft lira/ Mid. 15:11-22 tifcciiburp. I. , M.iiers. M R.. Smilli, A. K Il.li J ftn/uti l h e Tn.ucol. 21 21-,1.1 ^-- Drmkcr, C. K . Warren. M I'., lien Hell, Ci, A 11.17. / Indian //tv m >! 11;2H.1-R7-------------- 17. Grunt. T L., I'lnllips. W. U. Jt. Vil lirirme, D. C I'i7| Hull Pintrun Contain t oucol 6.102 OR llaglcy. G. i : . Reietiel, W, 1,., Crumar tic. I:. 1170, / OlHt:, Ana: Chern. 53 251-55 11. Koenian, J. It., Ten Nncvcr tic llr.nis*. M. L., Dc Vni, R. H. 1161 Nature 221:1126-20 100. l.iitcnl. C. L . Van Loon, E J I1: Pnw Stw Em iron thot, Afed 141 765-68 101. Villencuvc. D. C el al 117). Hull Em/, run, Contain. Tuxnvl 6 120-26 102. tin, Y., Uzawa. H,, Nntunii. A. 1171 Fukuoka Acta Med. 62:48-54 103. Ogawa, M. 1971, Fukuoka-fgaku-Zai- tin 62:74-77 104. Nnrback. D. II.. Allen, J. R, 1970. Fed. Pnv. 29:816-18 I0.V Norhack. D M . Allen. I. R. 1972. lifiw. Health Penpect. 1:1JV--43 iDb/Denncll. G. A.. Drinker, C, K . Warren. M. F. 1938. J. Indian Hvg. To.vco!. 20: 97-100 ------------- 107. Yap, It. It., Desaiah, D.. Cutkomo. L K. 1971. Nature 223:61-63 108. I'rcv4, 1.. JefTeries. D. )., Moore. N. W. 1970. Em nun. Po/ftif. I.-3-2J I Ctipynfht All nfhis retened 905833 CHEMOTHERAPY OF CANCER *587 Stephen K. Carter and Milan Slavik Division or Cancer Treatment, National Cancer Institute, Bcthcsda, Maryland IN T R O D U C T IO N Cancer is one or the oldest diseases afflicting mankind, and the efforts at treatment have been recorded as long ago as (he use of arsenic pastes in ancient Egypt. Today, cancer is second only to cardiovascular disease as the major cause of death in the i United States. Each year an estimated 650,000 new cases are diagnosed and over I one million known patients continue treatment. The major difficulties in mounting ` a rapid scientific assault on cancer are that it encompasses more than 100 clinically distinct diseases and is inextricably linked to fundamental life processes that still are ' not completely understood. T H E R A PE U T IC A PPR O A C H ES Several modes of therapy, including surgery, radiotherapy, and chemotherapy, are effective against cancer and have been developed to a point of practical use as either j single or combined modalities. In many instances, cure can be achieved through i removal or destruction of localized cancer, before it has spread to distant areas, by ' surgery and/or radiotherapy. Surgery is sometimes more successful when both the ! tumor and involved regional lymph nodes are excised. Radiotherapy is used to destroy localized tumors that are not accessible to surgery. Unfortunately, although they may eradicate the primary disease, the local modali ties often fail as a result o f the spread of disease to other parts of the body. In such instances, the demonstrated capacity of chemotherapy for controlling disseminated disease offers the greatest hope for reducing mortality in a number of different ' cancers (1). Like the other therapeutic measures, chemotherapy can be curative or palliative to varying degrees depending on the individual tumor (Table I). "Cure" means that the treated cancer patient has a "normal" lire expectancy, i.e. the same as that of a matched cohort in the general population. Cures, or at least possible cures, by antitumor drugs alone have been achieved in such diseases as choriocarcinoma, Burkitt's lymphoma, acute lymphocytic leu kemia, testicular cancer, and Hodgkin's disease. Chemotherapy combined with 157