Document 4JBpYQV8aOLYDe02rVOOLDJ3N

1340 20 Note/nl'cr 1971 Chnuhny and Indnsn f ft b ^ . I 1I The polyehlorobiphenyls, their occurrence j and significance: a review by R. Edwards H. J. Heim Co. Lid, Hayes Park, Hayes, Middlesex r v j >> *- < * ; . . 'tI ^ 1 i' : i i ! I i I J \ Pollution of the global environment by man is rightly receiving considerable attention because of the increasing realisation of possible long term effects on both the physical environment and living organisms. Clearly it is necessary to distinguish between short term toxic effects and long term ones (l.e. reproductive and carcinogenic effects), these latter being more difficult to assess. The chlorinated hydrocarbons used as biocides are well documented in their short term toxic effects, and with knowledge of their facile accumulation in the environment due to their considerable chemical stability, more work is being done on the long term effects coupled with tighter control of their use. With the latter the main points of entry into the terrestrial environment are through crop spraying and seed dressings with conse quent accumulation in the soil. From this point they can also reach the aerial environment secondarily by evaporation or 'co-distillation* and carriage in fine particulate matter. They arc also systemic in plants to varying degrees. Aqueous Tun-off carries them through the drainage system together with industrial effluent sources to reach the marine environ ment above the continental shelves. It is thus possible for these compounds to reach the lower members of the many food chains. Man'sdomeslicand industrial use of biocides for hygienic purposes leads to entry at various other points in the food chains. The very large concentration factor (10*) possible in these food chnihs is well known and in the final members (y.g. marine mammals, predatory birds, man) the concentrations can reach alarming proportions. Lipid solubility means that a large percentage of these residues will be stored in the fat depots of the body. The polyehlorobiphenyls (PC13s), with a very widely dispersed use throughout industry, have very similar pro perties to the chlorinated hydrocarbon pesticides, but are even more thermally and chemically stable. An important difference, however, lies in the routes through which they contaminate the environment.*Emphasis here is on indust rial effluents reaching the marine medium, and possibly the burning of industrial waste contributes relatively more to the aerial distribution. Although recommended for use in conjunction with pesticides, there is no documented example of this known to the author, so that distribution through crop spraying should not be a contributory factor. This fits the known pattern of distribution of PCBs in (lie environ ment, the highest concenlrations coining from the heads of fresh water food chains, marine organisms and sea birds. High levels arc also known in terrestrial avian predators, but only recently lias it been shown1 that in one region they can be found at levels comparable to those for oreanochlorinc pesticides. While relatively little toxicological work has been done on PCBs and some of the results are superficially con dieting, this can be explained and there can be no doubt tha they have very similar effects on mammalian and aviai ' metabolic processes to those of chlorinated pesticides, an< indeed that synergistic effects can occur between the twe classes.2 If any control over the use of PCBs is ultimate!' attempted this will be much more difficult than with pesti cidcs because of the very large number of uses to which the; are put. * There exists considerable difficulty in the analytical ficlc because these compounds cannot be separated easily fron pesticide residues, and this has probably resulted in quite : few reports in the past giving falsely high results for sonn pesticide residues.1 Unknown peaks in gas chromatograph' analyses were early recognised4- but it was not until Jen sen1 applied mass spectrometry to the problem that sonm of them were identified as PCBs. Properties and uses The PCBs received early nolice back in 1881s and were it widespread industrial use by 1930. The biphenyls, terpfi enyls, naphthalenes, and mixtures of these are chlorinaiei in varying degrees according to the use to which they an put,10 and arc marketed under trade names such as `Aroch lor', `Phenochlor', and 'Clophcn'. The products are comple' mixtures of the various compounds and isomers. They rang' from mobile liquids to crystalline materials or hard resin> and W'hilc the lower members arc readily soluble in non polar solvents they become progressively less so with increus ing extent of chlorination. They are extremely stable com pounds, not hydrolysed by water, acid or alkali, and will a thermal stability such that they are used in fire-proofing They find use in elastomers, adhesives, paints, varnishes printing, inks, putty and as general fillers. The excellen dielectric properties lead to widespread use for eiccirii insulators and as coolant insulators in transformers. Thi stability and their low vapour pressures make them ideal a lubricants, hydraulic fluids, liquid seals, cutting oils am vacuum diffusion pump oils. Employment in pnekagim materials has led to the contamination of food.11 Tlieix are a host of other uses, but finally it may be mentioned th.u both the Monsanto Company and the USDH have reports that they act as eficctivc vapour suppressants in inscciicid formulations and thus prolong the active life of an applies tion. However, it has not been acknowledged that PC'li have actually been used for this purpose commercial!' - As an ancillary fact, a patent for the production of I'CH from lindane residues lias been granted. This muliiplicit; of usage has repercussions in the analytical area bccauv DSW 032655 7*) STLCOPCB4016617 '/' ,, 20 tionwhcr !97l Chemistry and Industry t** ) many solvents, some adsorbents and other analytical materials, .and even the atmosphere of a laboratory can be ; contaminated by PCBs. > 5 .< !^ ' J ! f | ( . ' ? .-< ,j i* *-< j i` i l j < & 1 'i } ) . .I . 2 A ; i i \ ! ; ' \ | > .; i Occuncncc in the environment It is now well established that PCBs can be found in wildlife in many areas of the environment.1*1- 26 The highest levels nre generally associated with the industrial areas and - the ndjaccnt freshwater and marine food chains. The distribution is inevitably not quite so simple as this because of the migratory habits of some of the species involved 19*24 and the fact of widespread aerial distribution.28 Cohen and Pinkerton27 reviewed the latter in respect of pesticides, mainly over the North American continent, and found higher levels in dust than rainfall. Risebrough et a/.2s studied the carriage of pesticides in the trade winds coming from Europe and Africa by collecting dust from the air over the Barbados Islands, and detected from 1-64 p.p.b. organochlorine residues. Dust collected over the Californian coast contained some thousand times greater concentration of organochlorincs, but none could be found in dust collected from over the Central Pacific, although traces were inferred from the nature of the particulate matter. While no PCBs were delected in any of these samples, it was concluded that they were probably present in trace amounts. Tarrant and Tatton,28 however, who found organochlorine pesticides in rainwater samples taken from all over the British Isles showed that levels were highest in the summer months (c/. Risebrough et o!.2i) and in populous areas, also found PCBs in all of them although they did not estimate the concentrations. The importance of aerial distribution of pesticides relative to the hydrosphcric distribution has been stressed by Risebrough cl a!., and it is inferred that PCBs have a similar pattern of distribution. However, it would seem that with PCBs more emphasis should be placed on the hydrospheric medium, because an important part in the transfer to the atmosphere, via dusts used as carriers in agricultural applications, can be considered as low in this case. If the vapour pressures of DDT and PCBs are tnken as being of the same order, it would then be expected that atmospheric levels of PCBs would be low relative to DDT. The relative concentration or pesticides and PCDs in the hydrosphere and atmosphere have yet to be convincingly demonstrated. The outstanding feature of the distribution is the occurrencc in marine organisms on the continental shelves round North West Europe and North America, and also the extraordinarily high levels found in some freshwater avian predators, all associated with effluent from industrial activity.11,14,16-17*20'21,26 Along the west coast of the USA PCBs have been detected in estuarine and coastal waters in San Francisco Bay, San Diego Bay and Puget Sound (Washington). In areas remote from industrial activity round the Bay of California and parts of the Panama coast for example, birds' eggs contained 20-30-ag PCB each, but near the above mentioned industrial locations the eggs con" tained up to several hundred and sometimes over a thousand |tg PCB/egg. The east coast of (lie USA lias yielded similar evidence for contamination by PCBs. Holden and Marsden11 detected PCBs in seals from the Gulf of St Lawrence in shnl- V...... ... : 1341 low waters (Magdalen Islands) and in the deeper waters of the Cabot Straits. They have also been qualitatively detected in fish and shellfish from Texas and Georgia, and in the south, in the Gulf of Mexico, in estuarine waters at Charle ston, S. Carolina, levels bf less than 01 p.p.m. were found in fish and blue crabs.20 Duke et al. also monitored the results of an industrial leakage into the Escambia River which was carried through several inner bays through to the Gulf of Mexico off Florida. Maximum levels at source ranged from 486 p.p.m. in sediment to 20 p.p.m. in fish, Crustacea and sediment in the outer bays. The best indicators of contamin ant levels were static organisms like oysters (up to 3 p.p.m.). Round the coasts of North West Europe the situation is similarly, documented. Jensen et ok17 investigated levels in marine ecosystems in Swedish waters. The closed nature or the Baltic area perhaps leads to somewhat higher con centrations than those generally found on Atlantic and American coasts. Levels tended to be lower in waters off West Sweden and to the north of tiic Baltic proper, in the Guif of Bothnia, and higher going south from the Stockholm Archipelago to the South Baltic. The levels ranged from 0-002 to 1-0 p.p.m. in mussels and fish up to 150-240 p.p.m. in white tailed eagles. The concentrations were equivalent to the total DDT levels found. Kocman et alA6 qualitatively identified PCBs along the Netherlands coast from the Wadden Sea southwards to, and up, tiic Rhine, in mussels, fish and birds and their eggs. The uniformity of GC patterns suggested that they all originated from pollution of the Rhine. Holmes, Simmons and Tatton12 reported the pre sence of PCBs in vnarinc birds and their eggs collected from round the British Isles, and Holden and Marsden13 showed them to be present in seals and porpoises round the coasts of Scotland, being highest in those from the cast coast (sec below). Bonner,21 investigating the deaths of seal pups on the Cornish coast, found PCBs here (160 p.p.m. in blubber) higher than in comparable northern samples (34-48 p.p.m.), but less than in East Anglian specimens (350-520 p.p.m.). Presst. Jefferies and Moore, surveying PCD levels in British wildlife, reported an average of 4 (1-25) p.p.m. in the eggs of marine birds, nnd comparing the cast and west coasts of Scotland in respect of two sets of twenty five eggs somewhat higher levels (7 as against 3-6 p.p.m.) in the western samples. No PCBs were delected in whales analysed by Wolman and Wilson,29 and this is compatible with a distribution pattern confined to the continental shelves. However, this may be a rather naive use of the evidence because the .water solubility of PCBs. especially the higher chlorinated ones, is extremely low and the bulk of the PCB is more likely to be associated with sediment on the bottom and entering into the food chains mainly via bottom living organisms. Most whales feed on plankton, and thus might in any ease be expected to show low levels. A further point of perspective is also given by the fact that loss of lower PCBs from aqueous suspen sions when aerated has been observed/9 Holden26 has traced aqueous pollution back to one type of source. The work on seals in Scotland having shown that levels were highest in the Firth of Forth region, waiter samples from the surface nnd at depth from the estuary and river up to Glasgow showed no detectable amounts -. DSW 032656 ^ STLCOPCB4016618 1342 nnd only (race quantities in trunk sewer diluents. The zooplankton contained less than 0 03 p.p.m., and fish up to 2-6 p.p.ni. However, industrial effluents are usually passed to the sewage works together with domestic sewage, and so the sludge, which is dumped offshore, was examined. The fifteen samples analysed ranged from 1-185 p.p.m. PCB on dry weight, with two sewage plants giving con sistently high levels (50-160 p.p.m.). Sludge from Manchester exhibited somewhat lower levels, and that from London less again, but taking into account the varying outputs, each area was estimated to contribute roughly 1 ton/ year PCB contamination to the marine environment from sewage sludge. Jn the case of inland areas sludge can be disposed of by spreading over the land surface, and so offer a route to terrestrial food chains. The question of why it is that relatively low levels of PCB are found in man and his domesticated animals, posed in 196730 perhaps now has some answer. Distribution in terrestrial and freshwater ecosystems has largely been assayed in terms of the avifauna because of the effects of organochlorine pesticides and almost certainly PCBs on some bird populations. The DDT.PCB ratio has been used by Risebrough c( al. as an environmental index,14-24,35 but when data is compared consideration must be nude of the various biological factors, such as tissue distribution, species metabolism, migration, diet, health and age, which all affect residue concentrations. These authors have shown that the DDT,PCB ratio is low, below 2, near industrial areas, and increases with the distance away to become greater than 10 in remote regions. The geographical distribution in terrestrial and freshwater wildlife will be reviewed within the framework of these factors. Risebrough et n/.14 examined peregrine falcons and their prey, centring round the Bay of California. Falcons freshly migrated from the Arctic had low levels which increased with residence time in California; the levels in the Californian birds increased with age; and the indigenous adults showed the highest levels. The maximum Table 1 Tissue distribution of DDT and PCB in peregrines aiut their prey Total DDT BCP DDTIPCB p.p.m. p.p.m. ratio Peregrines: unhalchcd egg muscle liver body fat Prey: egg whole body muscle 102 too 77 50 151 59 ` 26-4 102 98 57 3-2 45 9-8 0 098 100 1-0 1-3 15-6 3-3 55 270 ' 20 November 1PJ] Chemistry and hhlii'irv values in Table I can be used to show the differences in tissue distribution. The same authors34 determined chlorinated hydroembon residues in breeding pelicans and cormorants in lakes to the north-west of the Great Lakes (Table II). As the birds used the same food sources the clear differences in results demonstrated a species difference probably due to variation in residue levels in the migration areas, but possibly meta bolic differences in terms of rates of excretion of organochlorines into the eggs may be involved. Birds have also Table II Chlorinated hydrocarbon residues in pelicans and cormorants Eggs pp'DDE p.p.m. PCB p.p.m. DDE: ratio Cormorant Pelican Fish (whole) ` 10-4 1-7 008 8 06 05 1-3 2-9 016 been studied in Britain12,19 and the extensive survey (599 samples) by Presst, Jefferies and Moore19 illustrates some of the factors involved; firstly habitat and migration (Table 111). Secondly; the eggs from marine birds from two colonies widely separated from one another demonstrates scry convincingly (Table IV) specific differences related to migration habits. The guillemot spends the longest time in Table IV Specific differences related lo migmtian habits DOJ/PCB ratio Si Abbs Head Guillemot Rarorbill Shag Kittiwake 0 233 0-500 0-625 0-665 . CalUmay 0-250 0-455 0 727 0 S75 coastal waters, the Killiwakc the shortest lime there, for breeding purposes only, and the Shag is essentially seden tary. The effect of health on relative and absolute levels is seen in the report by Bonnet3 1 on seal pup deaths. (Table V). Table V Effect of chlorinated hydrocarbon levels on seal pup health Total DDT PCB dot;pcb p.p.m. p.p.m. ratio Liver: Cornish 2-4 46 005 Not them (well fed) 0-6 4 0 15 Northern (starving) 2-C 6 0-33 Blubber: Cornish 111 160 0 07 Northern (well fed) 9-8 34 0-29 Northern (starving) 181 48 0-38 Table III Habit and migration factors affecting chlorinated hydrocarbon residues Liter Bird class No samples (a) Terrestrial predators: static ' partial migrants migrants (b) Freshwater (mostly static and mostly herons) (c) Marine 75 49 9 57 4 Mean p.p.m. 4-5 4-3 1-0 345 2-5 Css No samples 115 6 5 124 96 Menu p.p.m. 17 2-0 10 4-7 40 DSW 032657 STLCOPCB4016619 20 November 1971 Chemistry and Industry One of the most striking features of freshwater species is the extraordinarily high levels in herons at the head of a food chain where up to 900 p.p.m. have been found19 in British material. As the British heron is sedentary, occurs nearly all over the country, and there are few migrants from the continent, this species might be expected to be a good geographical index of PCB distribution. Unfortun ately nearly all the samples obtained in the survey of Presst ct at.*9 came from the Midlands and South East so that no clear pattern emerged. However, the age factor Js well illustrated by this species as the average liver levels for nestlings was found to be 5 p.p.m. while that for adults was 98 p.p.m. Diet is of course an important consideration, and means that different species from the same area can exhibit very different PCB concentrations. Thus, while birds feeding on insects have shown 0-1 p.p.m. (liver), raptors feeding on mammals yielded 0-50 p.p.m. It is necessary then, when comparing or interpreting data, to take into consideration all these factors. Terrestrial restriction of PCBs to near industrial areas would seem to be reinforced by the failure of Holden2^ to find them in freshwater fish in Scotland, and by Davis-'1 who failed to find them in beetles, earthworms, slugs and grasshoppers of one agri cultural area in England. To what extent arc PCBs found in human beings and foodstuffs? Jensen in 1966 first reported7 the presence of PCBs in human hair, and later reports12'23 indicated that levels in man and his foodstuffs were lower than those found in birds, and below 1 p.p.m. One exceptional case has been recorded,22 however. Rrccntly a very extensive survey of foodstuffs in Sweden sampled between 1967 and 1969, and analysed for organochiorine pesticides and PCB's, has been published.1 In a wide range of foods and food materials, PCB levels were found to be below 0T p.p.m. (90 per cent of 1400 samples) and comparable to DDT levels. The higher con centrations came from freshwater and marine fish, especially those with a high fa) content. Another case where relatively high levels were found was with milk. Cows excrete little DDT in their milk and here all eleven samples were below 0 03 p.p.m. DDT and 01 p.p.m. PCB on whole milk. In human milk relatively more DDT is excreted and the average over 22 samples was 0-107 p.p.m. DDT and 0-16 p.p.m. PCB. Other relatively high samples arc eggs and butter. (Table VI) Table VI Human milk Ebb. yolk Butler Total No DI>T 22 0-107 20 0-21 12 01 ` PCB 016 0027 003 DDTlPCB {p.p.m. whole material) ' 0 668 7*78 3 33 Toxicology Soon after the beginnings of industrial use of the chlorinated naphthalenes and biphenyls early in this century, human exposure was seen to lead to skin eruptions (chloracnc) and in animal inhalation and feeding experiments (1919), it was shown that liver damage occurred with the chlorinated naphthalenes. As a result of three human deaths, investi ng gations Were continued in the 1930s, and it was further demonstrated in work on rabbits that in the naphthalene scries the higher chlorinated mixtures were the most toxic. The work was expanded by Bennett cl al.i2<ii w ho also used mixtures including PCBs, and PCBs alone. A PCB con taining 65 per cent chlorine was used, and later one con taining 55 per cent. The substances were applied to rats by inhalation, subcutaneous injection, and oral means, and it was confirmed that the high chlorinated naphthalenes were more toxic than the lowqr ones, but that the PCB was more toxic still. Here, feeding at a lower rate (0 05g rat every other day) produced extensive mortality, and as with the naphthal enes resulted in yellowing and enlargement of the livers. Liver damage caused by these compounds had not disap peared two months after dosing had ceased. This damage caused the animals to be extremely sensitive to damage by other compounds, r.g. carbon tetrachloride (used as a solvent for these mixtures), and much smaller doses than normal were rapidly fatal. Miller in 194-434 experimented with a PCB containing 42 per cent chlorine and worked on guinea pigs, rats and rabbits, using feeding, subcutaneous, skin and corneal applications. He used single doses ranging from 69 to 690mg and courses totalling up to 1380mg (over up to 54d) and found that guinea pigs were the most sensitive, rabbits less so, and rats least sensitive in respect of liver damage. Damage was largely confined to the liver but in rats there was also hypertrophy of the spleen. The occurrence of hyaline bodies in the liver was confined to the rat. Von Oeltingen in 195535 found that even 0 05g/d fed to rats caused liver damage. Skin lesions were similar to those found in man. * Man's exposure to these chlorinated hydrocarbons leads initially to dermatitis, then liver damage with resultant jaundice, and Greenburg,3 reviewing the situation in 1939, concluded that there had probably been at least six human deaths from this cause. Bennett cl al,32 had measured the air concentration at thirty industrial plants and suggested a maximum allowable concentration (MAC) of 0-5ing m3 for telrachlorinalcd and higher chlorinated naphthalenes, with the observation that these levels had certainly been grossly exceeded over the previous twenty years. This work resulted in increased awareness of tire hazards from vapours of these compounds and elementary improvements in industrial conditions has largely eliminated this source of danger (but see Biros22). The American Conference of Government and Industrial Hygienists in 1953-'7 laid down an MAC for the lower chlorinated PCBs of 1 -Ome m\and for lhchigherchlorinatedoncs(`Arochlors' 1254-)0-5mg m VI"his appears to presume parallelism with the naphthalenes, and these figures are perpetuated in handbooks of industrial toxicology,38 but recent papers2-1*5 point to the reverse situ ation (sec below). These MACs are to be compared with those for `Aldrin' and `Dieldrin' (0-25mg 'm-\ tentative) and para- thion (OTmg'rti3). The oxidised chlorinated biphenyls are more toxic than the parent compounds.38 McLaughlin in 1963 published the results of toxicological studies on a number of chemicals which might be found in food39 using a sophisticated method based on injection into fertile hens' eggs. 25,000 eggs were used over three \ cars and strict controls set up. Among the compounds tested was the DSW 032658 STLCOPCB4016620 1344 . 20 November 1971 Chemistry ami Industry `Arochlor 1242' injected at 0 025 and 0-Iml giving a 0 and 5 per cent hatch as compared with over 95 per cent in the control group. Teratogenic effects were also noted in some of the chicks which did hatch. These results may be compaicd with those for 'Heplachlor', where 0 05 and O-IOrnl of a 1 per cent solution in propylene glycol (non-toxic) gave a 75 and 65 per cent hatch respectively. Hick ct al.40 endeavouring to identify the factor causing the chick oedema disease, following reports that the factor was highly chlorinated and that a plasticiser (PCB) used as a cage wire coating fed at 0 01 per cent or higher caused oedema in chicks, investigated the effect of `Arochlor 1242'. Groups of twelve chicks were fed on diets containing 200 or 400 p.p.nt. over a three week period, changes in weight being noted. Weight gain was lower with the 400 p.p.m. diet and indeed loss took place at the end of the period. Three chicks on this diet died. Here the hydroperi cardium volume was ten times larger than with the 200 p.p.m. level or the controls, the pancreas, kidneys and adrenals affected, and haemoglobin levels were lower. The PCI! produced similar effects to the oedema factor, but wras not so potent, and gas chromatography demonstrated that it was not tire same. Two groups of workers, Risebrough, Peakall et al. in (lie UJJ19.24.41-J and Jefferies, Moore, Pressl ct al. in Great Britain,19,44 have actively pursued the effects of organochlorinc pesticides and PCBs on birds. The decline in certain bird populations, especially raptors, has been attributed to the presence of organchlorinc pesticides, but it is hIso possible that PCBs have played a part irt this, not only because of their intrinsic toxicity but because il lias been shown (in insects,2 and below) tbal there are synergistic effects between some PCBs and DDT and `Dieldrin'. Lethal toxicity to the adult bird is not the only factor because it has been shown14-41 that organochlorine pesticides at the order of one p.p.m. are effective in inducing steroid hydroxylases in avian liver, Ihusleading to lowered oestrogen levels and reduced reproductive capacity. Added to this DDE has an entirely different effect on the reproductive system, that of causing eggshell thinning, which causes added failures in reproduction. Teratogenic effects may also occur because of the excrction/concentration factor in the eggs. Il is thus necessary to review the effects of the organochlorinc pesticides on birds in conjunction with (hose of the PCBs. Following work by Peakall,41 which demonstrated that pigeons fed with DDT at 10 p.p.m. and/or `Dieldrin' at 2 p.p.m. for one week had Higher levels of testosterone or progesterone metabolites than controls, Risebrough, J'cakall el al.19 compared the effect of DDE, DDT and PCB (`Arochlor 1262') in increasing the levels of polar metabol ites in oeslradiol metabolism, again using pigeon liver isolates in vitro. Their results arc given in Table VII, Table VII . Control I>1>K (40ing/kg1 DDT (40ine,'kg) PCU (20mpTj!) Polar metabolites farmed 29 76 93 160 moles) This PCB has about five times the capacity to reduce oeslradiol levels than DDT or DDE. The effect of a single dose of DDT may last for over two months. This work was extended to compare the effects of two different PCBs in kestrels, again using liver microsomc isolates.4' The kestrels were fed at 0-5 and 5-0 p.p.m. levels with `Arochlor. 1254' and `Arochlor 1262', and the results were as in Table VIII. Table NTH - Control 0 5 p.p.m. 5 0 p.p.m! Polar metabolites (nmolesjg microsomal fraction) T254' `1262* 0 13-65 60-5 0 19-05 47-95 While these figures do not clearly indicate the relative activity of these PCBs, it has been shown that `Dieldrin' and PCB arc much more active in reducing oestrogen levels than either DDT or DDE.42 That pesticides reduce oestrogen levels in mammals has also been demonstrated. Presst, Jefferies and Moore44 investigated the lethal effects of `Arochlor 1254' on Bengalese finches. Food containing higher levels of PCB (440 p.p.m.) was refused by the birds (100 per cent mortality not occurring) but it was still possible to calculate the LDjo as 253-6mg/kg/d. Seven out of the 38 birds died. Enlarged kidneys was the main feature, with in two cases increased volume of peri cardial fluid. While (here was a correlation betwecndoscralcs and liver concentrations, there w-as also considerable varia tion in levels (3-697 p.p.m.). Whether a particular con centration will be fatal will depend, as w ith organochlorine pesticides, on the condition of an animal. Considerable storage in fat is possible and until this reservoir is saturated, concentrations will probably not rise to lethal concentra tions in susceptible organs. So danger can arise in limes of stress (e.g. starvation or with the breeding cycle) when the fat reserves are mobilised releasing large quantities of PCB or whatever. The liver by itself in these birds may thus not be a good index because the liver fat reserves may vary considerably and will themselves be mobilised ultimately. The authors therefore suggest the brain/liver percentage as a useful index, being high in those birds that died (83-7 per cent and low' in tbc survivors (26 4 per cent). Tire l.D<0 for DDT is some thirteen times lower than for this PCB, but consideration has to be given to the fact that while the DDT mortality curve is' sleep (no deaths at 1000 and all dead at 1200mg/kg/d), the PCB curve is shallow, so that at low levels PCB may be more toxic than DDT. The authors con clude on the basis of this experimental work, and reasonably assuming that no drastic change in useage of PCBs is likely to have taken place over the past two decades, that few bird deaths have been caused by PCBs. However they state, without citing evidence, that the PCBs do not vary markedly in toxicity and this is at variance with recent work2,4-5-10 (see below), the PCB used here being of relatively low toxicity. Additionally the authors do not consider the possibility or synergistic effects.2 It was recognised that the position with sublclhal effects may be different. DSW 032659 STLCOPCB4016621  2Q November IV7I Chemistry and Industry Very little work'0,41"9 has been done on the cITcct of PCBs (Hnd tcrphcnyls) on aquatic organisms, despite tlie fact that it is known that some marine Crustacea and fish arc very sensitive to orpanochlorinc pesticide residues.4* For example Crangon vulgaris (brown shrimp) has an l.Cyo^Rh/ 15'c for DDT of 0.003-0-1 p.p.m., and levels as low as 0 0001 p.p.m. may be detrimental to some species of mollusc. One difficulty in the study of toxicity to aquatic organisms is the extremely low solubility of these com pounds in water and the difficulty of obtaining sufficiently stable emulsions.41'9 The use of solubilising agents, of low toxicity, overcomes (his. Zitko,49 using `Corexit 7664' to solubilise `Arochlor 1221' and 'Arochlor 1254'. carried out 192 hour tests with these compounds using Atlantic salmon parr. He found that concentrations above 2mg/l were lethal. Wildish48 using `Arochlor 1254' in emulsions, or solubilising with `Corexit 7664', carried out 30d tests with Ganvnarus occonicus and found lethal threshold values of 0-001 to 0-0Img/l (`Corexit') and 0-01 to 0-lmg/l (emulsions). Guthrie ct al*1 tested mixtures containing chlorinated tcrphcnyls and their oxidation products and found lethal threshold values of about 5mg/l and pertinently that low oxygen levels in the water enhanced the toxicity. Duke el at.20 who monitored PCB levels in biota and sediment in the Escambia Bay area of Florida as a result of an industrial leakage of PCB into the Escambia River, conducted both acute toxicity tests and 20d bioassays. 48h tests on pinfish and juvenile shrimps at the 100 p.p.b. level was not toxic to the fish but caused 100 per cent mortality in the shrimps. Oysters received a 96h lest and the effect was measured in terms of arrest of shell growth. Here 1 p.p.b. resulted in 19 per cent decrease in shell growth and 100 p.p.b. 100 per cent. Resultant whole body concentrations for the three organisms were 17,3-9 and 33 p.p.m. respectively. It should be noted that the oysters when replaced in PCB free water for three weeks recovered their normal growth rates. In the 20d assays using n concentration of 5 p.p.b., a 72 per cent mortality occurred in juvenile shrimps and 5 per cent in juvenile crabs. It would appear then from all this work that some Crustacea and molluscs are as sensitive to PCBs as they arc toorganochlorinc pesticides. Some toxicological work has been effected using insects.2-48 Morinrly2 dosed fourth instar nymphs of Chorihippus brunneus (grasshopper) topically with `Arochlor 1254' at 12-5, 50 or 200;/g levels, but found that dcftniic mortality was only associated with the 200ug group plus a possible sub-lethal effect associated with moulting (fat mobilisation). The maximum amounts of PCB in individuals of the latter group were !4iig (male) and 8pg (female). The work of Lichtenstein, however, is much more revealing as to the relative toxicity of the various PCBs und the synergistic effects with DDT and `Dieldrin*. Groups of 50 Drosophila meianogastcr were placed in contact with vessels coated with a layer or the substance or mixture of substances, and groups of 15 Musca domesitca were dosed topically. Tests of the individual substances showed that `Dieldrin' was some 25-30 times more toxic than DDT, and 1-R000 times more toxic than the PCBs. The higher chlorinated biphenyls, and the tcrphcnyls, rave rise to no mortality in the 24 or 48h tests, but toxicity increased with decrease in 1345 chlorine content in the iower half of the series. These results raise doubts ns to the relevance of the many papers w hich have used `Arochlor 1254', which here has little or no effect under these conditions. The synergistic effects with `Dieldrin' were positive with some of lower `Arochlors' and uniformly positive with pp'DDT up to `Arochlor 1254'. However, with the higher chlorinated PCBs and PCTs a reduction of toxicity was observed. While it is improper lo transpose results from one phylum to another and short term toxicity may have little bearing on long term effects, nevertheless this paper is a strong indicalion that consider able care should be taken in planning these toxicological studies. Work using mammals is equally sparse. A preliminary study by Saboika,50 using 'Arochlor 1254' and `Arochlor 1260' or DDT in single doses of l-10mg/kg ('Arochlor's) or 0-25mg/kg (DDT) carried out behaviour tests on mice over periods of 4 to Z4h after administration. There is a clear difference between the two groups of substances, DDT probably attenuating and PCBs probably enhancing central inhibitory systems. The paper by Bitman and Cecil45 surveying the oestrogenic activity of DDT analogues and PCBs in terms of the 18h glycogen response of immature rat uterus assumes considerable importance in relation to a lot of the work cited above. The stereochemical require ments are quite strict, and in general for diphenyl-methane and -ethane, and triphenylmethanc compounds activity is restricted to those where either the pp positions are vacant or filled by hydroxy or melhoxy groups, being inactive where halogen or alkyl groups are present. So tire pp' compounds perthane, kelthanc, DDE, DDD and mclhoxychlor are inactive. How-cver, pp'DDT is active and the op'isomer sonic sixteen times more so, while of the others mentioned only op'DDE gains a response. `Arochlor's 1221-48'arc about half as active at /y/DDT, but ihc higher members arc inactive, (cf. Lichtenstein). In perspective though these compounds only have something like 10-4 times the activity of natural oestrogens, but this fits well with the observed pattern of steroid hydroxylase induction in birds, where DDT and PCB are very active but DDE is less so. Perhaps another significant point is that the oo' and /y'biphcnols have an equivalent oestrogenic activity. The lower chlorinated PCBs could be degraded in the atmosphere as has been shown by laboratory experiments where the greatest diminution in one gas chromatograph peak was found where PCBs on an aqueous surface were subject to UV irradialion.51 At the same time it lias been observed1--17 51 1 hat the lower chlorinated PCBs tend lo be absent in w ildlife samples, particularly in birds, and it may be speculated to what degree ihcrc may be differential excretion or in \i\o breakdown, and what effect this has. A recent study by Vos el o/.52 reveals another important aspect. They discov ered that two out of three 60 per cent chlorinated PCBs contained highly toxic oxvecnatcd impurities. These two commercial preparations (`Phenochtor DP6`, `Clophcn A60") when injected into hens' eggs at the 3-5nig level caused almost 100 per cent mortality whereas the third sample (`Arochlor 1260') gave a relatively low mortality. A fraction containing, no PCBs was isolated from one of them by 'FlorisiP column chromatography and shown to be toxic. DSW 032660 STLCOPCB4016622 1346 Gas chromatography and mass spectra showed this fraction to contain tctrachloro and pcntachloro-dibcnzofurans which were, however, masked by hexachloronaphthalenc and hep- tachlorobiplicnyl respectively, thus limiting the accuracy of quantification. The pcntachlorodibenzofuran was estimated to be at about the 5 and 20 p.p.m. level in the two samples. That PCB exerted a similar effect to that of the chick oedema factor (CEF) had been noted previously,40 and that toxico logical studies vising PCBs had produced variable results, 1,2,3,7,8,9,-hexachloro dibenzodioxin has now been identi fied ns one of the oedema factors" and it may be recalled that the toxic factor in the weedkiller 2,3,5-T was shown to be a tctrachloro dioxin.'3 In fact these chlorinated dioxins and dibenzofurans are very highly toxic groups of compounds. C-2ng pcntachlorodibenzofuran is needed to cause 100 per cent mortality in hen eggs as compared toO OSgg ofhexa- chlorodibcnzo-yi-dioxin. The occurrence of the dibenzo furans in PCBs is associated with the use of sodium hydrox ide in the distillation of crude PCB. Pcntachlorophcnol (PCP) and 2,3,4,6- tetrachlorophenol arc possible precursors of CEF and have been found to be present in toxic oleic acids.34 Jt is evident then that other compounds besides (he PCBs themselves should besought for in wildlife and that indivi dual compounds as well as commercial preparations should be used in toxicological studies. Unfortunately the indivi dual PCB compounds nre not readily available. Holden and Mnrsden55 have already noted the presence of unidentified polar compounds in wildlife extracts. It is to be hoped that the current FDA programme-6 on the toxicology of PCBs takes into account all these factors. Analysis PCBs are extracted together with chlorinated hydrocarbon pesticides in routine residue analyses,5? and being complex mixtures of compounds with GC retention times on non polar columns almost identical to a number of pesticides, notably of the DDT group, present an analytical problem which is not completely soluble by gas chromatographic means alone. Chemical conversion of the pesticides, leaving the PCBs almost unchanged, provides a partial but not completely satisfactory solution, but group separation is fundamentally sounder, this of course providing additional evidence of identity. Both thin layer chromatography and Column chromatography have afforded quite good partial separation of PCBs from pesticides and the best scheme-'8, claims to lenve only `Aldrin' with the PCBs, with which there is very little interference by the PCBs. A number of workers*8.22.59.00 have confirmed the presence of PCBs in living tissues by means of mass spectrometry, but apart from this means the quantification of PCBs presents severe problems because of the large number of compounds involved and that the individual compounds are not readily available, so that most authors have only been able to calculate approximate figures. , Gas chromatography retention data for PCBs is now adequately documented1216-'8'26 5'0'61 (and also1-2-13,14'20, 24,25,30.59) an(j pn non-polnr columns the main region of interference of PCBs nnd organochlorinc pesticide residues with one another may vary from the point of emergence of 20 Novcn\bcr 197/ Chrmisuy and IndnMix ,, pp'DDE that of pp DDT. PCBs may continue to emerge with retention limes up to four or five times that of DDT. It has been noted in this laboratory that response to PCBs relative to organochlorinc pesticides can be small on some columns, and from the viewpoint of determining pesticide residues, can ameliorate the situation. However, using more polar columns, c.g, `QF-1' or PCBs emerge largely prior to the DDT group, which allow s simple quantification of the latter, but may still leave an unsatis factorily complex chromatogram. Improved resolution of PCB compounds has been claimed63 using novel stationary phases. One alternative has been to alter the retention time of pesticides by derivalisation, leaving the PCBs intact, and or course aiding the identification of the pesticides. Jensen59 used a mild nitration technique adapted from Erro et al. and originating from the Schcchtcr-Haller method, claimed that the PCBs remained unaltered while members of the DDT group were effectively removed, although other organochlorincs {e.g. `Toxaphene', hcptachlor epoxide, lindane and BHC) are not removed. This scheme (1:1 HNO3/H2SO4 Tor 5min at 05c) was followed by Risebrough et fl/.,14-50 but Reynolds61 found that DDT derivative peaks ultimately emerged on the chromatogram making for an unprofitably long analysis time. Moreover, some lower chlorinated PCBs appeared to have been affected by the procedure. Saponification with alcoholic potash13,14-'0 leads to the dchydrochlorination of p/j'DDT, pp'TDE, and `Toxaphene', with the derivative peaks appearing earlier in the chromatogram, and the PCBs reportedly unaffected. BHC is destroyed by this procedure. PCBs have also been differentiated from DDT using carbon-skeleton chromato graphy.64 Separation prior to gas chromatography is to be pre ferred not only because simpler chromatograms can be obtained but because this will give nearly as much evidence as to identity as derivation. Thin layer chromatography, reverse phase paper chromatography12 and column chroma tography afford means of obtaining partial separations of organochlorine pesticides from PCBs and fractions can easily be obtained where only `Aldrin', `Hcptachlor', and pp'DDE remain with the PCBs. The former two arc not very important in respect of the gas chromatography separation because there is usually little interference between them and PCBs, but pp'DDE can emerge with the major PCB peaks using non-polar columns. Thin layer chromato graphy has given this sort of separation using silica gel15 and alumina,1,2 and in column chromatography Holden and Marsden26,45 claimed good separation of PCBs using either alumina, silica gel, or both in series with long narrow columns. Reynolds61 documented a separation with `Flori- sil\ while Bevenue and Ogata62 commented on their failure to reproduce this work in terms of pesticide separations only, and noted the differences in activity between `regular' and `PR Florisil'. This reviewer has found no difficulty in obtaining this separation using `Florisil'. Armour and Burke58 in a carefully documented paper showed that it was possible to carry out a separation leaving only `Aldrin' with the PCBs. For this they used silicic acid paitly deacti vated with 3 per cent water mixed with cclitc and eluted the OSW 032661 STLCOPCB4016623 20 November 1971 Chemistry and industry PCBs ('Arochlor's 1254 and 1260') with petroleum ether. `Arochlor 1254' needed the larger volume of eluant and the separation was more critical. The cautionary note is added that any trace of polar solvent in the sample will make the separation impossible and pp'DDU. will emerge with the PCBs. Also, the separation is only possible provided that the column (204-5g) *s not over loaded (j.e. not exceeding 20;jg PCB). This then solves the main separation problem leaving on non-polar gas chromatography columns only a small PCB peak which may interfere with the estimation of`Aldrin'. These authors have also documented the separ ation- of chlorinated naphthalenes.6' Confirmation of identity has been achieved by combined gas chromalography/mass spcctromctry,,S22-'9'6(l but gener ally quantification is not simple because of the large number of compounds involved and because these are not readily available individually for reference purposes. If it can be assumed that a fraction contains only PCBs (r.e. in a column chromatography or gas chromatography effluent) and that the composition on a gas chromatography trace conforms to that of a commercial mixture, then microcoulomctric estimation will give an answer. Jensen et at.,'1 using a combination of mass spectrometry, ECGC and microcoulomclry obtained results which were only accurate to about a factor of two. With the same assumptions electron capture detection can be used, referring to commercial PCB mixtures26 either by estimating the total peak area*9"'9'63 or basing the calculation on one1,16,19 or more20 suitable peaks. pp'DDE or `Dicldrin* may be used ns an internal Standard.16,J;0 One empirical approach calculated one PCB peak ns pp'DDT and multiplied by a factor of ten to obtain a result;24 another66 took the total arca:wcight ratio to be equivalent to that for DDE; and another 19'50 assumed the response of each peak to be equivalent to DDE and applied a correction factor from the use of microcoulomctric detection (the authors did not have permanent access to a microcoulomctric detector). Gregory67 studying the electron capture coefficients of mono- and dichloro- and methylbiphenyls showed that there is over a tvventyfold variation between the chloro compounds. Zitko49 determined the concentrations of PCB in frcsli and salt water by means of ultraviolet spectrophotometry and fluorescence. While the lower chlorinated PCBs can be prepared easily68 and only simple mixtures formed when using the Ullmann reaction, the higher members arc more difficult to make singly. Discussion * The decline of certain bird populations w as associated with the use of `Dicldrin' seed dressings and has been attributed to lethal toxic effects. With increasing awareness of these dangers, better monitoring and usage control, at least in developed countries, lethal toxic effects are progressively less likely to occur. Rather, the significance of PCBs (and pesticides) to man and other organisms must now be seen in the context of sub-lethal effects having long term influence on populations through the media of reproductive processes (reduction in fertility, delays in breeding), teratogenic and carcinogenic effects on both the parent and later generations. LD50 tests, even over a long period, arc irrelevant from this viewpoint. Certainly it is true that severe mammalian mi liver damage and death can result from high PCB levels but these arc only reached in a few foodchain heads, and the normal levels found in man arc not of this order. To be set against this, however, is the finding (in LDyo terms) that while with DDT there appears to be a definite 'no effect' level this is apparently not true for PCB. Precisely what compounds arc responsible for the toxicity of PCBs is not yet clear, but it seems certain that it concerns the lower chlorinated compounds and probably the oxidation products in vivo or in vitro. It also emerges that impurities in some commercial mixtures arc certainly highly toxic, and if the fact of synergistic effects, though demonstrated as yet in one area only, is taken into account then the picture becomes a very complicated one. Clearly it is extremely difficult to carry out strictly controlled toxicological studies at a feeding level of the order of 1 p.p.m. over a long period, and in terms of mulliccneration tests. The need for multi generation tests may be related to DDT, where, despite many years study, it has only recently been indicated that, with only the original parents dosed, carcinogenic effects may occur in later generations (6th generation mice). DDT may again be used to illustrate the sort of effect which may be looked for. In California, Oregon and Washington, genetic changes in the fruit fly population have been shown to result from heavy spraying programmes in these areas, and in the latter two stales were tied to two specific forest spraying programmes. The pattern of these genetic changes can also be correlated with spread by winds over long dist ances. With PCBs the major dispersal medium is probably water, but otherwise there are no essential differences in the situation. The PCBs are Spread all over the continental shelves which are fed by industrial effluents. The toxicology of the weedkiller 2,4,5-Ts? and of mercury residues69 has recently come to the fore and they present some parallels with the PCBs. While in contrast to PCBs there is a definite, but small, contribution to agricultural pollution, by mercury from seed dressings, the industrial contribution must lead to a similar marine distribution to PCBs, although as yet very little is known about this area. Mercury, in contrast to PCB, is only cumulative in living tissue to a limited extent, and there is a definite natural contribution from the sea floor. The massive aerial use of the weedkiller 2,4,5-T as a defoliant by the Americans resulted in leratologicnl as well as direct toxic effects due to traces of a chlorinated dibenzodioxin. It is as well that PCBs arc not used in such fashion because it has now been shown that some commercial preparations contain traces of chlorinated dibenzofurnns which are also highly toxic. Water pollution is receiving considerable attention within the traditional framework of oxygen deficiency, reduced and oxidised nitrogen, temperature and so on, bill the type of pollution problem presented by PCBs, DDT and so on is largely ignored. In a recent official report on toxic chemicals, which recommends further work to appraise the situation in fresh, estuarine and coastal waters, there appears to be a large conceptual gap. Commenting on the presence of DDT in raw sewage, this is dismissed as a significant source of riverine pollution because DDT is solid attached and largely remains in the sewage sludge, but what happens to the sludge is blithely' ignored. The ironic situation is ol DSW 032662 STLCOPCB4016624 I MB 20 November 1971 Chemistry and industry course that ihc sludge is commonly dumped in estuaries or even spread out over the land so that pollutants such as the PCBs arc recirculated through the food chains. These arc hut a few aspects of environmental pollution which can ultimately lead to man's own detriment. In many eases the users of pollutant materials, industrial or domestic, have no conception of their own insidious contribution to pollution, and in the ease of the very useful PCBs it is very difficult to see how their disposal can be controlled to minimise pollution. From the point ofviewofrcstrictingtypes of use to those least likely to result in pollution, one prod ucer, Monsanto, has made a very responsible move70 in this direction, but as PCB manufacture is no longer covered by. . patents this may not be effective. It is obvious that with their ubiquitous presence the effects of PCBs and associated compounds must be investigated with great thoroughness, it is not only to preserve bird populations or other wildlife but to prevent long term changes in man himself that such searches are directed. . The author is grateful to (he 11, J. Heinz Co. Ltd, for permission to publish this paper. References * Westbb, G., Noten, K. & Andersson, M,, Var Tiida, 1970,10 7 Lichtenstein, 1'. I'., Schulz, K. R., Fuhremann, T. W. A Liang,T. T., J, tcon. Eh!., 1969, 62, 761 * Kocman, J. H. A Genderen, H. van, J. Appl EcoL, 1966, 3 (Suppl.), 99 4 Harrison, R. I)., J. Set. FdAgiic., 1966, 17, 10 3 Roburn, J., Analyst, Loud., 1965, 90, 467 . 7 Walker, C. H., Hamilton, G. A. ft Harrison, R. B., J. Sci, FdAgiic., 1967, 18, 123 7 Anon., New Srient., 1966, 612 * Sclunidt, H. A Schultz, G., Ann. 1881, 207, 378 Penning, C. H., hid. Eng. Chem., 1930, 22, 1180 u> Anon., Technical Bulletin O-Fl/J, 'The "Aroctilor" polychlorinated polyphcnyls', Monsanto II Bailey, S., Banyan, J'. J. & Fishwiek, F. B., Chem. & Ind., 1970, 705 12 Holmes, D. C., Sinnnons, J. H. A Tatlon, J. O'G., Katun, Loud., 1967,216, 227 . ` Holden, A. V, A Marsden, K.. ibid., 1967, 216, 1274 74 Risebrough, R. \V,, Ricchc, P., Pcakall, D, B., Herman, S. G. & Kirven, M. N., ibid., 1968, 220, 1098 3 Report for 1966-8, Monks Wood Experimental Station, Nature Conservancy, 1969 . i* Kocman, J. H., Ten Noever Dc Bramv. M. C. & Dc Vos, R. II,, Katun, Loud., 1969, 221, 1126 17 Jensen, S., Johncls, A. G., Olsscn, M. A Ottcrlind, G., ibid., 1969, 224,247 . Bapley, G. H.. Reicltcl, W. L. A Cromarlic, II., J. Assoc. Off. Anal. Chem., J970, 53, 251 . 17 Press!, J., JcITciics, D. 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J., Mutchlcr, M. K. A Fitzhugh, O. G,, Toxic, appl. Pharmac., 1963, 5, 760 40 Flick, D. F., O'Dell, R, G. Sc, Childs, V. A., Poult. Sci., 1965, 44, 1460 43 Pcakall, D. B,, Nature, Land., 1967, 216, 505 47 Idem, Sclent. Am., 1970, 73 43 Lincer, J. L. ft Pcakall, D. B., Nature, Loud., 1970, 228, 783 44 Moore, N, W., Biologist, 1969, 16, 157 43 Hitman, J. ft Cecil, H. C., J. agrk. Pd Client., 1970, 18, 1108 46 Moriarty, F., Entomoiogia exp. appl., 1969, 12, 206 47 Guthrie, J. E. A Acres, O. E., Bull. Enr. Contain. A Toxicol, 1970, 5, 145 43 Wildish, D. J., ibid., 1970, 5, 202 47 Zitko, V., ibid., 1970, 5, 279 30 Sobotka, T. J., Information Bulletin, BIBPA, 1970, 9, 363 *' Risebrough, R. W., Reichc, P. A Olcoll, 11. S., Bull. Env. Contain. A Toxicol, 1969, 4, 192 37 Vos, J. G., Kocman, J. H.t Van Dcr Maas, Ten Noever Dc Brauvv, M. C. A Dc Vos, R. H., Pd Cosinel. Toxicol, 1970, 8, 625 31 Anon., Nature, Land., 1970, 226,'309 34 Higginbotham. G. R., Ress, J. A Rockc, A., J. Assoc. Offic. 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Oignnic Syntheses, 1969, 49, 4 5 77 Anon., Information Bulletin, BIDPA. 1970, 9, 212 70 Tinker, J,, New Scientist and Science Journal, April 1 1971, 16 /.... / . QSW 032663 STLCOPCB4016625