Document mq8m5NZ364RmpmYGBKRvEG4d4
Polychlorinated Biphenyls
Another Long-Life Widespread Chemical in the Environment
David B. Peakall and Jeffrey L. Lincer
The recent finding that pelagic birds dying on the coasts of Great Britian. had polychlorinated biphenyls (PCBs) in their livers in concentrations of several hun dred parts per million (Bourne and Mead, 1969) shows that these compounds are present in the ecosystem in large amounts. Thus, it seems worthwhile to summarize and evaluate our current knowledge of these compounds.
Structural and Physical Properties
The picture is complicated by the fact that we are not dealing with a single com pound. The basic structure of PCBs is shown in Figure I. Any of the positions marked with an x can be substituted by chlorine. Widmark (1968) has calculaTcd that of the 21(1 possible combinations K)2 are probable. 11 is criteria for these lim itations are those, compounds containing five to eight chlorine atoms per molecule and the number of chlorine atoms per ring differing by not more than one.
The commercially available Aroclors (Monsanto Company Trademark) are des ignated by numbers (Monianto Technical Bulletins). The first two digits represent ' the molecular type: 12 - chlorinated bi phenyls: 25 and 44 - blends of chlorinated biphenyls and chlorinated terphenyls (75% biphenyl and 60% biphenyl, re spectively); 54 - chlorinated terphenyls. The '-last two digits give the weight per cent of chlorine. Thus, Aroclor 1242 is a chlorinated biphenyl containing 42% chlo rine. The biphenyls commercially avail able from Monsanto range from 21% to 68% chlorine. Mass spectrographic studies of Aroclor 1260 (Koeman et al., 1969a) show the presence of 11 isomers: five con taining six chlorine atoms, five containing seven chlorine atoms, and one containing eight. Bagley et al. (1970), studying Aro clor 1254, found 18 compounds: one con taining three chlorine atoms, four contain ing four chlorines, four containing five chlorines, five containing six chlorines, and four containing seven chlorines. Thusi _
The atrthofi are currrfttty at the lanfmalr Laboratory, Coned Univcnily, Ithaca, N.Y.
the number of compounds present is, for tunately, much smaller than is theoretical ly possible.
PCBs are chemically inert, are not hy drolyzed by water, and resist alkalies, acids, and corrosive chemicals. They have low volatility, their boiling points ranging from 278 C for Aroclor 1221 to 415 C for Aroclor 1268 (Penning, 1930). All are stable to prolonged heating at 150 C, and the lower Aroclors can be distilled at atmospheric pressure without appreciable decomposition. PCBs arc described as insofuhlc in water and very soluble in hydro carbon solvents, although no exact figures appear to be available. Nothing is known about the biological decomposition of PCBs, but it is likely that they are more stable than DDT and its metabolites since they iaek the ethane component between the aromatic rings, which is the site of action of most of the transformations of DDT. Thus, PCBs have the necessary physical and chemical characteristics for persistence and accumulation up the food chain.
Use of PCBs
Polychlorinated biphenyls were first de scribed in the literature in 1881 (Schmidt and Shultz, 1881), and the successful com mercial production was achieved by the
Swann Company in 1930. In that year the physical characteristics and commerical possibilities of these materials was de scribed by Penning (1930). PCBs are now manufactured by Monsanto in the United States (Trade name Aroclor). Prodelcc in France (Phenochlor), and Bayer in Ger many (Colphen). Other manufacturers are located in Japan and the Soviet Union. No figures of the amount of these mate rials produced annually are available, but to judge from the uses listed in Table 1 they may be very large. The uses listed in the tabic arc only suggested applications taken from Technical Bulletin 306 of the Monsanto Chemical Company, and again there is no information on the extent to which these recommendations arc acted upon by the manufacturers of plastics and resins.
The use of highly chlorinated Aroclors for extending the kill-life of formulations containing chlordane, aldrin, and dieldrin arc mentioned under miscellaneous appli cations of Aroclors. This possibility has been considered in a number of papers. Sullivan and Hornstein (1953), Hornstein and Sullivan (1953), and Tsao et al. (1953) found that the chlorinated terphenyl Aro clor 5460 increased the residual persis tence of lindane. Tsao et al. (1953) consid ered that there was some indication that chlorinated polyphenyl may have a syner gistic effect with lindane. Duda (1957)
PCS
%x
<
X POSOBU. FONTS FOR
.
SUBSTITUTION Of CHUMNE .
<*> .
CD-1-0
a-c-a
oar
I a
255270 osW
a
. OCHLOROOlPttim. Fig. I. Basic structure of PCBs (A) and possible reactions o( PCBs (8).
958 O
VBioScicncc Vol. 20 No. 17
STLCOPCB4060961
/.< .
sprayed dm saplings with a lindane Aro-
2) Separation. The chemical techniques of separating DDT and PCB for further
cior 5460 mixture (1:4) and then tested preliminary to quantitation of residues in tests.
the residual effect on the leaves to infes samples containing both PCBs and chlo Saponification with alcoholic NaOH or tation with elm leaf beetle (Galerucetla rinated hydrocarbon pesticides fall into KOH will dehyrodrochlorinatc Pcrthane,
xanthomelaena). He found that leaves two groups-tho.se necessitating the de Toxaphene, DDD, and DDT to their re treated with lindane plus Aroclor were struction or alteration of one or more of spective olefins (Archer and Crosby,
protected longer and that the insecticidal the compounds, and those which do not. 1966; Klein and Watts, 1964). Risebrough
effect was more rapid than with lindane
Included in the first group is nitration. et al. (1969) reported that PCB peaks are
alone. Peaks corresponding to Aroclor Treatment with a 1:1 mixture of sulfuric not removed or displaced but gave no 5460 have not been detected in the envi acid nitric acid al 0 C for 5 min destroys data.
ronment. However, under conditions of or alters aldrin, p,p'-DDE, p.p'-DDD The second, and in some instances
temperature and flow-rate commonly used (TDE), p.p'-DDT, and dieldrin such that more desirable, group of analytical tech
for gas chromatographic analysis these they can no longer be detected al the niques allows the special. separation of
compounds would not be detected (Reyn olds. 1970).
Nearly 25 years ago it was noted that,
original position on the chromatogram. This procedure leaves unaffected PCB, lindane, and BHC (Jensen and Widmark,
many chlorinated hydrocarbon pesticides from PCBs. Reynolds (1969, 1970) re ported on an activated Florisil column
Aroclor 1242 was one of 175 compounds 1967). A more rigorous nitration with a technique which separated heptachlor,
out of 6000 tested that was effective 1:1 mixture of sulfuric acid-fuming nitric aldrin, DDE. and PCB with the first elu
against mosquito (Aegvps) larvae (Deon- acid for 15 min'at room temperature re tion (60 ml n-hexanc) from lindane: hep
icr el al.. 1946). Lichtenstein el al. (1969) moves, in addition to DDT and its related tachlor epoxide. DDD, and DDT with the
tested the effect of adding a variety of products, aldrin. heptachlor, Keithane, second elution (40 ml 50% ethyl ether in
biphenyls and terphenyls to DDT and di- Pcrthane, Tedion, Telodrin, and Trithion hexane). Armour and Burke (1970) devel
eldrin with respect to their toxicity to while lindane, heptachlor epoxide, toxa- oped a method utilizing a silicic acid-
house and fruit flies. It was found that phene, and Slrobane are not removed Cclite column eluting aldrin and PCB
PC8s had very low toxicity to house flies (Erro et al., 1967). Risebrough et al. (1969) with the first fraction (250 ml petroleum
when given alone but PCBs increased the reported that this nitration also removed ether), and lindane, heptachlor. hepta
toxicity of dieldrin and DDT, especially the chromatographic peaks of PCBs. Rey chlor epoxide, dieldrin, endrin. p,p'-
the latter. The effectiveness of these com nolds (1969) reported that his attempts to DDE, o,p'-DDT, p.p'-DDT, and p.p'-
pounds' decreased as the chlorinated level nitrate samples were not fully successful DDD with the second fraction (200 ml
increased. For example, Aroclor 1224- in in that there appeared to be loss of some acetonitrile hexane methylene chloride--
creased the mortality of fruit flies from of the more volatile PCBs while peaks 1:19:80). Koeman et al. (1969a). using an
59% to 93%, whereas Aroclor 1268 in" with longer retention times appeared. activated Florisil column, eluted the apo-
creased it to only 77%.
Armour and Burke (1969) reported that lar compounds including DDE and PCB
Analytical Methods
complex chromatograms resulted after with hexane, and then dieldrin and endrin ' nitration which could not be related to the with 10% diethyl ether in hexane. Mul-
I) Identification. Since various com pounds with electron-capturing properties have been tentatively identified in atmo spheric samples in the past (Abbott et al.,
unreacted DDT-PCB mixture, and nitra hern (1968) reported on a method which tion'was not pursued as a practical means utilized silica gel-coated thin-layer plates
Taik i.
Um am aI t+rtHtimtw* hipbaaytt itkn Iraw UmaatJ TltUnl SaBatia 0/Pl-MI '
1966). and some pesticides are capable of hybridizing in the soil to form a new com pound (Bartha, 1969), it is importanPthat '
Maiand widi wfccft Aiadw m caafcM
Edy*ft <1
Aiad au4 with at %
Atadw 1241, 1244 A I2M (7-9%)
Sawtoy pUrtotw it ieptrr* flaw* ratwiaM*
the presence of PCBs in field samples be
proven beyond doubt. Identification by means of a combination of high resolution . gas chromatography and mass spectrom
Anda* 1221. 1212,
1212 (It*
Ca-yiaipdtat la aaA* taamaca.
latma aakfc-toacA a (bat-taw w*P*b**
etry has been carried out by three inde
Arad* 1214 (41%)
pendent laboratories in Sweden (Widmark, 1967), Holland (Koeman et al., 1969a). and the United States (Bagley et al., 1970). Widmark's report states that all ~ peaks were identified by mass spectrom* etry (although no data were given), but Koeman and co-workers gave full experi- . mental details, and Bagley et al. (1970) demonstrated that most chemicals in the eagle samples examined were components '
74|mwi
Andw 122! A 1241
uru
Arad* 12M (14-11%) Aradw 12*4 {14-2W
r 1221 (2%) I 12*4 (VIru
lactam (Waiul m4 aadttw* itattm id
lAiaw niii
Iflacti** ad acaawakfl fca raiwAaat. lactam Maaftt W Mw-fUaa taidwta*
adtwwUa^ papvdat
fCinM in
CM
5 y> D
of Aroclor 1254. Thus, despite a recent statement by the Monsanto Chemical
i 1241 (44%) i 1214 II IW
Company (in Risebrough. 1970) that the
CiV Mte
i 1242 (A-14%1
case for labeling the peaks in question as PCBs was not proven, there is enough
TmM
i 1244 Q%\ d
J
evidence to convince an unbaised scienti fic jury.
> 1242 11%)
September l, 1970
959
STLCOPCB4060962
and a hexane/cthyl ether (98.2) solvent fact many of the original samples con epoxide generally represented a majority
system. The plates were developed, tained little or no p.p'DDT, it was pos of the apparent values. Before and after
sprayed with a silver nitrate solution, and sible to estimate relative PCB values. values for p.p'-DDE and dicldrin were
exposed to UV light. The plates were then Anderson and his co-workers also saponi not significantly different. Obviously, the
divided into five horizontal sections. Di- fied samples to remove interfering p.p'- magnitude of error may vary depending
eldrin. endrin. r-BHC, hcptachlor DDT and p.p'-TDE and then quantitated on the trophic level sampled and certainly
epoxide, p.p'-DDD, p.p'-DDT, o,p'- PCBs as Aroclor 1254 by relating sample with the area from which a sample is col
DDT, and p.p'-DDE (in that order) were peaks 9 and 10 to the corresponding peaks lected (Riscbrough et al., 1968, Jensen et
found in the first four fractions, while of an Aroclor 1254 standard. Reynolds al., 1969). Since the publishing of ade
most of the interfering compounds found (1970) employed a method similar to quate separation techniques, there is no
in wildlife samples were found in the fifth Koeman et al. (1969a) but based his quan reason why there should be any error in
zone. Bagley ct al. (1970) used this meth titation on an average of two 6r more pesticide quantitation contributed by
od but mentioned that zones three and peaks. In addition, his results were re PCBs.
four contained practically all unknown ported as Aroclor 1254 or 1260 depending
components as well as p.p'-DDT (zone on the overall pattern of the chroma
Toxicology
three) and p.p'-DDE (zone four). Armour tographic peak profile. It is clear that we
and Burke (1969) used precoated (alu are still relatively unsophisticated in our
Despite some recent studies, the toxi
minum oxide) sheets and nrheptane and PCB quantitation methodology and will cology of PCBs remains rather poorly
2% acetone/n-heptane for solvent sys continue to estimate only relative amounts known as compared to that of the chlo
tems. PCBs (Aroclors 1254 and 1260) and of PCBs in field samples until we synthe rinated hydrocarbon pesticides. For ex
DDE were not separated, but p.p'-DDT size the individual PCB components com ample, no definite work has been done to
and p.p'-DDD were completely sep monly found in the ecosystem and are establish LD50 values for the various
arated from PCB by both solvent systems. able to speak in terms of these individual formulations of PCBs.
Another possible means of separating in peaks as we do for most pesticide residues.
1) Acute, single dose experiments.
terfering substances is to use a series of However, it has been kindly pointed out Tucker and Crabtree (1970) found that a
differing polarity columns in the gas chro (Risebrough, pers. comm.) that, with ref single dose of 100 mg/kg Aroclor 1254
matograph at the time of determination. erence to biological significance, the cor (stomach tubed in oil) was fatal to two out
This is less time consuming and may be rect order of magnitude and accurate rela of three rats, while 500 mg/kg was not
useful when operating conditions can be tive amounts of PCB give the essential . fatal to three rats. Aroclor 1268 killed one
selected such that PCB peaks are absent information. This is because biological rat out of three at 500 mg/kg, 1000 mg/
in the region where sought pesticides- ; effects, such as enzyme induction, are re- kg, 2000 mg/kg, and 4000 mg/kg. Smyth
emerge (Simmons and Tatton, 1967).
latcd to degree of chlorination, and the (1931) found that a 4 g/kg (degree of chlo
3) Quantitation. Kocman ct al. (1969a) existing methods give some indication of rination not stated) was nontoxic to guinea
semiquantilativcly measured the residues this activity. Therefore, that information pigs and rabbits, but this appears to be
in Japanese quail fed phenochlor DP6 by would be lost if stress were placed only due to the fact that material which was
using one of the peaks in a phenochlor upon quantitating individual peaks.
given as a paste passed through the intes
DP6 mixture as a standard. Riscbrough
4) Magnitude of Error. Ever since PCB tine unabsorbed. Tucker and Crabtree
(1969) quantitated relative levels of PCBs peaks were recognized for what they are, (1970) found that Aroclor 1242, 1254,
by assuming that each PCB compound residue chemists and other researchers 1260, and 1268 at a dose of 2000 mg/kg
produced the same peak height with the interested in pesticide residues have was not fatal to mallard ducks (four
electron capture detector as the same asked what magnitude of error is likely to groups of three birds each).
amount by weight of p.p'-DDE. After result from ignoring the presence of 2) Acute, feeding experiments. Mon
summing the heights of the individual PCBs. Only recently have studies either santo Bulletin 306 states that 100 ppm
peaks, the total was multiplied by a factor directly or indirectly resulted in an esti diet had no effect on rats, although no
derived from measurements of standard mate of this error. Anderson et al. (1969) details of the studies were given. The ex
solutions with electron capture and micro- quantitated p.p'-DDE, p.p'-DDD, and periments of Bennett et al. (1938) in which
coulometric detectors. Jensen et al. (1969) p,p'-DDT in five egg samples before and 0.05 g/rat of 65% chlorine biphenyl was
reported PCB amounts as the sum of all after saponification. There was no appre given orally every other day led to 50%
PCB components and based the estimate ciable change in the p.p'-DDE, but ap- mortality. If one assumes a body weight
on a combination of mass spectrometry parent p.p'-DDD was reduced by ap of 200 g, then the alternate day dose is
and microcoulometric and electron cap proximately 58% and p.p'-DDT by 90%. roughly 250 mg/kg. which can be com
DSW 255272
ture detection. Even with this elaborate Reynolds (1970) lookcd at a large number pared to oral LD50 for DDT of 113 mg/kg
approach, these investigators suggest that of samples before and after his PCB- (Frear, 1968). Miller (1944) found that
the method is still rough and may be cor Florisil separation and found that the two oral doses of 69 mg of 42% chlorine
rect only within a faetor of 2. Anderson et actual p.p'-DDD residue (relative to the biphenyl a week apart were fatal to guinea
al. (1969) devised a method for obtaining apparent residue) represented from 0 to pigs. At an estimated body weight of 400
a crude estimate of PCB residues as Aro- 7% in California gull (Larus occidentalis) g, this gives a dose of 170 mg/kg. Tucker
clor 1254 from chromatograms where sep aration had not been attempted. On an empirical basis, it was found that Aroclor
fat, 0% in cormorant (Phalacrocorax auritus) eggs, 80%'in 10 pooled mallard (Anas platyrhynchos) duck eggs, and from 0 to
and Crabtree (1970) fed rats diets contain ing 10 and 1000 ppm Aroclor 1254. One rat out of six on the low dose died: this
1254 could be quantitated by considering 104% in great blue heron (Ardea cinerea) mortality was considered to be due to
peak 10 as p.p'-DDT and multiplying that eggs. Respective values for p.p'-DDT other causes. Four out of four of the high value by 10. Since this peak had originally were 0 to 53%, 13 to 41 %, 100%, and 18 to group died within 53 days and the cal
been quantitated as p.p'-DDT, and in
TV102%. Actual residue levels of heptachlor culated intake was 1330-1520 mg/kg.
960
vl.
BioScicnce Vol. 20 No. 17 v
STLCOPCB4060963
food intake of the 1000 ppm group was excess of 2000 ppm. This finding is in hcxobarbilal, in vitro rates of aniline hy-
only 79% of the control group.
agreement with the findings of Dale, droxylation and demcthylation of p-ni(ro-
Presst et al. (1970) have examined the Stickel, and co-workers that the brain anisolc, and the rale of excretion of*
toxicity of Aroelor 1254 to Bengalese levels are the best indication of acute dicldrin. These workers studied 10 com
finches (Lonchura striata). This is a diffi toxic levels.
pounds ranging in chlorine content from
cult species for which to calculate the McCunc ct al. (1962) found no mor 21% to 68% and found that all the effects
dietary intake. Due to their dependence tality with chickens fed 100 or 200 ppm increased with increasing chlorine con
upon unshelled food, it is only possible to Aroelor 1242 in their diet for a 4-week tent. For example, 50 ppm of Aroelor
present the PC D-laden food for a few period. On diets of 400 ppm and 800 ppm, 1221 reduced hexobarbital sleeping time
hours a day (Jefferies, 1967). Loss by the mortalities over a 4-weck period were, by 11%, whereas for Aroelor 1248 and
evaporation and loss by spillage must be respectively, 50% and 90%. During the 1268 the figures were, respectively, 35%
allowed for. and increase of weight by def first 3 weeks, the mortality figures were and 48%. Thus, the sublethal effects have
ecation must be kept to a minimum. 10% and 50%, respectively. Flick et al. direct correlation with chlorine content,
Thus, the calculated dietary intake is sub (1965), using the same material at 400 while the lethal effects appear to be in
ject to more error than is usually the case? ppm in the diet, had three birds out of 24 versely correlated (Tucker and Crabtree,
Presst cl al. (1970) also measured the con die in a 3-week period. Koeman et al. in press). Lincer and Peakall (1970) noted
centration of PCBs in the liver: they (1969a) found that a diet containing 2000 an increase of the in vitro rate of melabo;*v
found that the range was large (i.e., 70 ppm Phenoclor DP6 caused complete lism of estradiol in kestrels fed 0.5 and ^
697 ppm. in birds that died compared to mortality with Japanese quail (5/5) in 5 5 ppm Aroelor 1254 in their diet and also
3-634 ppm in those that survived). These 13 days and rats (8/8) in 1-56 days.
demonstrated increased levels of cytoplas
authors conclude that Aroelor 1254 has Schoeltger (unpublished) found that the mic RNA with the higher dietary level
only 1/13 the toxicity of DDT, although 96-hr TLm for Aroelor 1221 using cut using a cytophotometric technique.
the different shape of the mortality throat trout was 1.2 mg/1 and for Aroelor ,, Tucker (unpublished) found that a sin
curves--steep with DDT, gradual with 1260 was 60.9 mg/I. In general, they gle oral dose of 500 mg/kg Aroelor 1254
PCB--makes comparison difficult. Jef found that the toxicity of Aroclors was caused regular egg laying of Japanese
feries and Walker (1966) found good cor inversely proportional to their percentage quail (Coturnix coturnix) to turn first to
relation between calculated dietary intake chlorination and directly proportional to scattered egg production and then to stop
and liver concentrations for pp'-DDT in their solubilities. These figures suggest completely for a week. The scattered eggs
the Bengalese finch. However, other that PCBs are two to three orders of mag had shells 9% thinner than normal, but
workers (Dale et al., 1963: Stickel ct al., nitude less toxic to fish than DDT. Work thickness returned to control values when
1966: Stickel and Stickel. 1969) have con -by Lichtenstein et al. (1969) on house and regular laying was resumed. Mallard
sidered that levels in the brain are a more fruit flies found that PCBs were 40-300 ducks dosed with 1000 mg/kg of Aroelor
reliable index of toxic levels than those in times less toxic than DDT, the toxicity laid one or no eggs before stopping for 1
the liver or whole carcass.
decreasing as the chlorine content in 2 weeks. The few eggs laid after the sin
De Vos and Koeman (1970) fed Pheno- creases. Thus, it appears that the lower gle large dose of Aroelor had shells 18%
clor DP6, Clophen A60, and Aroelor 1260 vertebrates and invertebrates are much thinner, and again eggshell thickness was
to chickens at a dosage of 400 ppm. Mor less susceptible than mammals to direct normal after resumption of regular laying.
tality was complete (20/20) for those birds toxicity from PCBs.
The period before egg laying has been
on Phcnoclor in 12-58 days and in 13-29 3) Sublethal effects. As with the. chlo noted to be increased in the ring dove
days for Clophen. The mortality for Aro- rinated hydrocarbon pesticides, the most (Peakall, unpublished). It is possible that
elor was only 3/20 for a 60-day period. important effects tire long-range sublethal the mechanism involved is increased rate
This differential effect is unexplained and effects. The pathologic changes in various of metabolism of circulating estradiol in
is surprising in view of the fact that all organs are summarized in Table 2. The the liver (Peakall, 1970). Anderson et al.
three formulations contain 60% chlorine. table shows some interesting differences (1969) had suggestive evidence that
These workers measured the residue lev between mammals and birds. The most PCBs affected eggshell thickness, al
els in the liver, and, for some birds, in the striking finds in mammals are alterations though to a less extent than DDE. Pre
brain, fox chickens dying during the ex to the liver, whereas fluid in the peri liminary results with ring doves support
periment. Although there was consider cardial sac, kidney damage, and reduced this conclusion (Peakall, unpublished).
able variation, most of the brain levels spleen was found in birds.
'
were between 210 and 420 ppm, which
McLaughlin et al. (1963) found that 25
Levels of PCBs Found in Nature -
can be compared to 50-80 ppm for DDT mg Aroelor 1242 injected into the yolk
(Stickel et al., 1966). On the basis of this sac of chicken eggs caused complete mor
Roburn (1965), comparing total chlorine
work, PCB is 1/4-1/5 as toxic as DDT. Little difference was noted between the three different PCB-' formulations, al though the numbers of determinations involved was rather small. If this finding is borne out by subsequent work, it would suggest that differential absorption from the gut or differential penetration of the
tality, whereas 10 mg caused 95% failure and teratogenetic effects were noted among the young that hatched (beak deformity, edema, and growth retardant).
Induction of hepatic hydroxylating en zymes has been demonstrated in the pi geon (Risebrough et al., 1968), rat (Street et al., 1969), and American kestrel (Falco
(by concentration cell techniques) with results calculated from gas chromatog raphy, found that some unknown chlorine compounds were present in several tissue samples and eggs of wild birds in Great Britain. The first identification of these materials was by Jensen and it is stated (Anonymous, 1966) that residues in feath
blood brain barrier is involved. The liver sparverius) (Linccr and Peakall, 1970). ers collected in Sweden go back to 1944.
values were more variable. There was a Street and co-workers studied the effects PCB residues have been reported in wild
considerable number in the 200-400 ppm of a diet of 50 ppm and 100 ppm on sleep life from Canada (Holden and Marsden.
range, but there were several values in ing time induced by a standard dose of 1967: Anderson ct al., 1969; Reynolds,
September I, 1970
vJ
DSW 255273
STLCOPCB4060964
f ,'-y-n -
TABLE 2. Pathologic changes induced by PCBs
/
Tiestinsnt
Animal
Uvar
.
a Kidney
% Pericardui* and Peritonei*
Other Observable Changes
References
*
Single oral dost of 69 HQ (42% d)
Guinaa Pig Rat Rabbit
Small fat droplet* through lobules, slight to moderate central atrophy, focal necrosis noted in a few animals.
Essentially normal
No noteworthy changes
Adrenals, spleen, end pancreas shewed ae noteworthy changes.
Miflor (1644) .
300 mg daily for 6 days (66% a)
50 mg drily for tip to S month! 65% Cl)
Rat Rat
Cells swollen, hyaline granules present, most died within few days.
Enlarged (33% weight increase), large number of hyaline globules in cytoplasm. Several died during experiment
'
Bennett at al. (1131) Bennett ,.v
26. 60. & 100 ppm in diet for 15 days 121-68% Cl Aroclors)
Rat
Incurs. in weight, affect increasing with tacrrrsriig chlorine content. Aroder 1232-10%. 1242-12%. 1254 14%. 1261-24% at SOppaL
Street et d. (In press)
100 ppm in diet 200 ppm in (bet 400 ppm in diet 800 ppm in diet (Arodof 1242)
Cbickaa
No effect No effect Enlarged and mottled Damaged
Damaged
Slight Hydropericirdium Hydropericardium Hydropericardiom.
hydroperitonerua. Enlarged.
.
McCone at al. (1962)
200 & 400 ppm in dint for 3 wssks (42%. Atodet)
Chickaa
Na changes noted
Paleness at 200 ppm. extensive hemorrhage, and enlargement at 400 ppm.
Increased fluid in pericardial sac at the higher concentration.
Paleness of pancreas, en largement of adrenal and small spleen et low concen trations. At higher concen trations pale eream*olored eenertas. adrenals hemorrhagic.
Rick at *.(13651
Various dam (54% Cl Aradar)
8engine Finch
No weight changes
Weight we* 32.4% of brain weight for controls end 63.5% for these dying from PCB poisoning.
Slight weight increase, a few showed liqeid in pericardial sac.
Presst st si. (la press)
400 ppm m diet for 60 day* 160% a*)
Chicken
Centrolobalar necrosis (compd 1 and 21. Liver weight increased froai 2.76 g/100 g to 4.31 f/100 g (compd. 3). Fatty degenratio*.
Tubular ddetatron, (compd. 1 and 2) Bart with compd. 3.
Hydropericirdium common with compds. 1 and 2. Rare with compd. 3.
Increased porphyria, spleen smalt with reduction of red pdp and atrophy of white pulp (compd. 1 and 2). Spleen decreased from 0.146 g/100 g to 0.136 g/t00g, compd. 3).
Vas and Koeaiaa (la prase)
*ftodr DM (eaH 1). Qm*bm AW (** 2) 4Af*d#f 1260lc*a*4.3) wwvmai DManaM tfNdi
mSrtf4 uakn AleticUn M m eamfi. I m4 2 mbit 60 fen.**? 15% --itnitr w t--pi. 5.
DSW 255274
1970), Germany (Fiuczynski and Wend-
land.'1968: Koeman et al., 1967), Great
Britain, (Holmes et al., 1967; Presst and
Jefferies, 1969: Presst et al., 1970; Holden
and Marsden, 1967), Netherlands (Koe
man et al.. 1967; 1969), Sweden (Anony
mous. 1966: Jensen el al., 1969), and the
United States (Anderson et al., 1969;
Risebrough et al,, 1968; Risebrough,
1969)..
'
%
Biological Magnification
No detailed studies, such as those for DDD at Clear Lake (Hunt and Bischoff, I960) and DDT and its metabolites in Lake Michigan (Hickey et al., 1966), have yet been made for PCBs.
The most detailed studies currently available are those of Jensen et al. (1969).
The figures (mean, range of values, and sample size) given in the table below are taken from their paper.
PCBs (ppm in extractable fat)
Muud
.
Herring
Seal
Guillemot eg|s
Baltic
Stockholm Archipelago
4.3(1.9-8.6) (40) 5,2 (3.4-7.0) (15)
6.8 (0.5-23) (18) 34(16*44) ( 3) 250(140*360)( 9)
5.1 (33-8.5) 30(16-56)
( 4) ( 3)
White-tailed Eagle
Pectoralmvsde
14,000 (8400* 17.000) ( 4)
Braia
E*
Heron "
910(490-1500) ( 3)
540(250*800) ( 5)
9400
( I)
The levels in three species of fish in Clear Lake in 1968 were 0.03-0.005 ppm (wet
weight) compared to 0.098 ppm in the breast muscle of a western grebe (Rise brough et al., 1969). Anderson et al. (1969) found that in most fish extracts the levels of PCBs were less than 0.1 ppm. whereas the levels in the eggs of cormorants (Phalacrocorax auritus) were 5-9 ppm. Presst. Jefferies, and Moore (unpublished) found that the livers of fish-eating birds in the British Isles ranged up to a maximum of 900 ppm (wet weight), bird feeders up to 70 ppm, mammal eaters to 50 ppm, and inseclivores to I ppm. Unfortunately, no average values or prey items were in cluded.
The physical properties of PCB and the available residue data -clearly indicate that these materials are capable of bio logical magnification up the food chain.
962 'V5
BioScicnce Vol. 20 No. 17
STLCOPCB4060965
Ratio of DDT (o I'CB
Significance of Current Levels
cide residue analysis. F.D.A. Laboratory In
Riscbrough cl al. (I%8) anil Riscbrough (1970) have examined (he ratio of total DDT, i.e.. DDT and its metabolites to PCB. He has found that the ratio DDT/ PCB was 1-2 in San Francisco Bay and 5-, 10 for seabirds in the Pacific: in the Gulf of California, a region relatively remote from contamination, the ratio was 9-10. Vermeer (quoted in Reynolds, 1970) in western Canada found a DDE/PCB ratio . of 7 for California gull tissues and 13 for great blue heron eggs. In the Baltic the ratio was 1-2 (Jensen et al., 1969), al though along the west coast of Sweden the ratio was as low as 0.15. In grebes in' the British Isles the ratio was 0.4-0.8 (Presst and Jefferies, 1969). For sea-bird eggs, Presst et al. (unpublished) found ratios of 0.06 to 0.5.
The overall impression is that the amount of PCB in tissues tends to paral lel that of DDE, at least in local ecosys tems, and the DDE/PCB ratio is lowest near industrial areas suggesting that PCB is not carried quite so readily to remote areas. Nevertheless, the variation of the
In view of the similarity of PCBs to
formation Bull. No. 9IX. II p. 1970. A method for separating poly-'
DDT and its metabolites, the addition of chlorinated biphenyls from DDT and its anal-v,.
PCB residues to the environment is rough ly equivalent to an increase of DDE resi dues. However, since a synergistic effect of PCBs on DDT has been demonstrated
ogs .J. Assoc. Ojjic. Anal. Chem. (in press). Baglcy, G. E., W. L. Reiehel. and E. Cromartie.
1970. Identification of polychlorinated bi phenyls in two bald eagles by combined gasliquid chomatography-mass spectrometry.
in insects (Tsao et al., 1953), this pos J. Assoc. OJJic. Anal. Chem.. 53: 251-261.
sibility should not be overlooked in higher organisms. The enzyme induction effects of PCBs have been well documented, and
Bartha, R. 1969. Pesticide residue interaction creates hybrid residue. Science. 166: 1299 1300.
Bennett. G. A., C. K. Drinker, and M. F. War
carbonic anhydrase inhibition is likely.
ren. 1938. Morphological changes in the
The effect of PCBs on photosynthesis is a critical experiment that has not been done. Wurster's (1968) experiments with phytoplankton should be repeated with
livers of rats resulting from exposure to cer tain chlorinated hydrocarbons. J. Ind. Hyg. Toxicol.. 20: 97-123. Bourne. W,, and C. Mead. 1969. Seabird . slaughter. B.T.O. News. No. 36, p. 1-2.
PCBs.
, Dale, W. E., T. B. Gaines, W. J. Hayes, Jr., and
The most critical area for research on PCBs is to discover the major source(s) of escape into the environment. Legislative
G. W. Pearce. 1963. Poisoning by DDT: Re lation between clinical signs and concentra tion in rat brain. Science. 142: 1474-1476. Deonier. C. C., H. A. Jones, and H. H. Incha.
control of a material escaping as a side
1946. Organic compounds effective against
effect of its use may have a different set of problems than the control of pesticides which are broadcast as a function of their normal use. The evidence suggests that it
Anopheles quadrimaculatus. Laboratory test.J. Econ. Entomol.. 39: 459-462. Duda, E. J. 1957. The use of chlorinated poly phenyls to increase the effective insecticidal life of lindane. J. Econ. Entomol.. 50: 218
is important to find the leak and stop it. 219.
Erro, F., A. Bcvenue. and H. Beckman. 1967. A
ratio is small enough to suggest that the
method for the determination of toxaphene
routes of dispersal are similar. Since the evidence points to aerial fallout as the .
Acknowledgments
route of dispersal of the chlorinated hy drocarbon pesticides (Riscbrough et al., 1968; Frost, 1969), it is likely that this is also the main route for PCBs. The path ways by which PCBs escape into the eco system are poorly known, although the possibilities have been recently discussed at some length (Risebrough, 1970; Rey nolds, 1970). Since a large number of plastics and resins may contain PCBs (Table I), the most likely route is combus tion of these materials. This supposition remains to be tested. The possibility that PCBs could be derived from DDT should also be considered. The possibility that this con-yersion occurs in tissue is most
We are grateful to Dr. Kocman (Uni versity of Utrecht), Drs. Presst and Jef feries (Nature Conservancy, Great Britian). Dr. Reynolds (Ontario Research Foundation), Dr. Street (Utah State Uni versity), and Dr. Tucker (U.S. Fish and Wildlife Service) for advance copies of important material. Some of the work presented here was carried out under NIH Grant ES00306, Dr. T. J. Cade, Principal Investigator. The review was written while one of us (D.B.P.) was an Established Investigator, American Heart Association. Thanks go to Dr. T. J. Cade for reviewing the manuscript.
in the presence of DDT. Bull. Environ. Con
tam. Toxicol..2: 372-380.
Fiuczynski, V. D., and V. Wcndland. 1968. The
population of Milvus migrans in Berlin 1952
1967. J. OrnithoL. 109: 462-471.
Flick. D. F.. R. G. O'Dell, and V. a. Childs.
1965. Studies of the chick edema disease. 3.
Similarity of symptoms produced by feeding
chlorinated biphenyl. Poultry Sci., 44: 1460
1465.
Frear. D. E. H. 1968. Pesticide Handbook-
Entoma. College Science Publishers.
Frost, J. 1969. Earth, air, and water. Environ
ment. 11: 15-33.
Hickey, J. J., J. A. Keith, and F. B. Coon. 1966,
An exploration of pesticides in a Lake Michi
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Holden. A. V.. and K. Marsden. 1967. Organo-
chlorine residues in seals and porpoises.
Nature. 216: 1274-1276.
Holmes, D. C., J. H. Simmons, and J. O. 'G.
unlikely for two reasons. First, it has never been detected despite the detailed work on the metabolism of DDT. Second, the
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