Document 7RxDk3LvwRkeJyBv5RbBEaMMe

1)40 20 Novrmbrr IV7I Clu miVry and ImtMutry The polych Iorobiphenyls, their o^currence and significance: a review by R. Edwards Ioc H. J. Heinz Co. Ltd, Hayes Park, Hayes, Middlesex Pollution of the global environment by man it rightly receiving considerable attention became of the increasing done on PCBs and some of the results are superficially con flicting, this can be explained end there can be no doubt that realisation of possible long term effects on both the physical they have very similar effects on mammalian and avian environment and living organisms. Clearly it is necessary metabolic processes to those of chlorinated pesticides, and to distinguish between short term toxic effects and long term indeed that synergistic effects can occur between the two ones (r.r. reproductive and carcinogenic effects), these latter clesses.3 If any control over the use of PCBs is ultimately being more difficult to assess. The chlorinated hydrocarbons attempted this will be much more difficult than with pesti used ns biocides are well documented in their short term cides because of the very large number of uses to which they toxic effects, and with knowledge of their facile aocumuletion ' are put. in the environment dm to their considerable chemical There exists considerable difficulty in the analytical field stability, more work is being done on the long term effects because these compounds cannot be separated easily from coupled with tighter control of their use. With the latter pesticide residues, and this has probably resulted in quite the main points of entry into the terrestrial environment few reports in the past giving falsely high results for some ere through crop spraying and seed dressings with conse pesticide residues.3 Unknown peaks in gas chromatography quent accumulation in the soil. From this point they can also analyses were early recognised4-* but it was not until Jen reach the aerial environment secondarily by evaporation sen7 applied mass spectrometry to tlse problem that some or 'co-distillation' and carriage in fine particulate matter. of them were identified as PCBs. They are also systemic in plants to varying degrees. Aqueous run-off carries them through the drainage system together Properties and one with industrial effluent sources to reach the marine environ The PCBs received early notice back in 18811 and were in ment above the continental shelves. It is thus possible for widespread industrial use by 1930.* The biphenyls, terph- these compounds to reach the lower members of the many enyls, naphthalenes, and mixtures of these are chlorinated foodchains. Man'sdomesticandindustrial use ofbiocides for in varying degrees according to the use to which they are hygienic purposes leads to entry at various other points in put,10 and are marketed under trade names such as 'Aroch- the food chains. The very large concentration factor (103) . lor', 'Phenochlor', and 'Clophen'. The products are complex possible in these food chains is well known and in the final mixtures of the various compounds and isomen. They range members (e.g. marine mammals, predatory birds, man) from mobile liquids to crystalline materials or hard resins, the concentrations can reach alarming proportions. Lipid and while the lower memben are readily soluble in non solubility means that a large percentage of these residues polar solvents they become progressively less so with increas will be stored in the fat depots of the body. ing extent of chlorination. They are extremely stable com The polychlorobiphenyls (PCBs), with a very widely pounds, not hydrolysed by water, acid or alkali, and with dispersed use throughout industry, have very similar pro a thermal stability such that they are used in fire-proofing. perties to the chlorinated hydrocarbon pesticides, but are ''""'They find use in elastomers, adhesives, paints, varnishes, even more thermally and chemically stable. An important printing inks, putty and os general fillers. The excellent difference, however, lies in the routes through which they dielectric properties lead to widespread use for electric contaminate the environment Emphasis here ia on indust 1 insulators and as coolant/insulators in transformers. This rial effluents reaching the marine medium, and possibly the stability and their low vapour pressures make them ideal as burning of industrial waste contributes relatively more to the lubricants, hydraulic fluids, liquid seals, cutting oils and aerial distribution. Although recommended for use in vacuum diffusion pump oils. Employment in packaging conjunction with pesticides, there is no documented example materials has led to the contamination of food.11 There of this known to the author, so that distribution through are a host of other uses, but finally it may be mentioned that crop spraying should not be a contributory factor. This fits both the Monsanto Company and the USDH have reported the known pattern of distribution of PCBs in the environ that they act as effective vapour suppressants in insecticide ment, the highest concentrations coming from the heads of formulations and thus prolong tbs active life of sn applica fresh water food chains, marine organisms and sea birds. tion. However, it has not been acknowledged that PCBs High levels are also known in terrestrial avian predators, but have actually been uaed for this purpose commercially. only recently has h been shown1 that in 00a region they can be found at levels comparable to those for orgaoochlorine Aa an ancillary fact, a patent for the production of PCBs from lindane residuee has been granted. This multiplicity pesticides. While relatively little toxicological work has bean of usage has repercussions in the analytical area beciuas HONS 0*6216 *<i Mn.W'fW/ ( Ihmistry and Industry many solvents, some adsorbents and other analytical materials, amt even the atmosphere of a laboratory can be contaminated by PCBs. Occurrence In the environment tl is now well established that PCBs can be found in wild life in many areas of the environment.1 12-26 The highest levels arc generally associated with the industrial areas and the adjacent freshwater and marine food chains. The distribution it inevitably not quite so simple as this because of the migratory habits of some of the species involved1'*?* and the fact of widespread aerial distribution.2* 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/.25 studied the carriage of pesticides in the trade winds coining 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 oforganochlorines, 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 detected in any of these samples, it was concluded that they were probably present in trace amounts. Tarrant and Tatton,2* however, who found organochlorine pesticides in . rainwater samples taken from all over the British Isles showed that levels were highest in the summer months (cf, Risebrough cl al.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 c< a/., and it is inferred that PCBs have a similar pattern of distribution. However, it would teem 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 taken 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 of pesticides and PCBs in the hydrosphere and atmosphere have yet to be convincingly demonstrated. The outstanding feature of the distribution is the occur rence 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.1**14*1**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 eoast for example, birds' eggs contained 2030pg PCB each, but near the above mentioned industrial locations the eggs con tained up to several hundred and sometimes over a thousand l*g PCB/cgg. The east coast of the USA has yielded similar avidawca for contamination by PCBs. Holden end Manden13 detected PCBs ia teals from thp Guff of St Lawrence in shal low waters (Magdalen Islands) and in I he 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 of less than 0* I p.p.m. were found in fish and blue crabs.20 Duke et a/, 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 (he 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 a/.17 investigated levels in marine ecosystems in Swedish waters. The closed nature of 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 the Baltic proper, in the Gulf 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 130-240 p.p.m. in white tailed eagles. The concentrations were equivalent to the total DDT levels found. Koeman et alM qualitatively identified PCBs along the Netherlands coast from the Wadden Sea southwards to, and up, the 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 murine birds and their eggs collected from round the British Isles, ami lloldcn and Marstlcn14 showed them to he present in seals and porpoises round the coasts of Scotland, being highest in those from the east coast (see 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 staples (34-48 p.p.m.), but leu than in East Anglian quomens (330-520 p.p.m.). Presst, Jefferies and Moore, surveying PCB levels in British wildlife, reported an average of 4 (1-25) p.p.m. in the eggs of marine birds, and comparing the east and west coasts of Scotland in respect of two seta of twenty five eggs somewhat higher levels (7 as against 3*6 p.p.m.) in the western samples. No PCBs were detected whales analysed by Wolman and. Wilson,29 and this is compatible with a distribution pattern confined to the continental shelves. However, this may be e 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 asweiated 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 caaa be expected to show low levels. A further point of perspective is alio given by the fret that loss of lower PCBs from aqueous suspen sions when aerated hat been observed.49 Holden** 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, water samples from the surface and at depth from the estuary and river .up to Glasgow showed no detectable amounts MONS 066217 I M2 20 November IV7I Chemistry ami Indastry and only mice quantities in trunk sewer effluents. The r.wplnnklon contained less than 0-03 p.p.m., and fish up to 2*6 p.p.m. 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. Pv'B 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 I ton/ year P^ B contamination to the marine environment from sewage sludge. In 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 hit domesticated animals, posed in 1967)0 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 el al. as an environmental index,n,J4`23 but when data is compared consideration must be made 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 at.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 Tails I ! P*ar dUtribatbn of DDTmtd PCB in peregrines and their prey Total DDT , BCE DDT1FCM ppm. 'P.p.m. ratio ftregHnes: unhitched sag muscle liver body fit l>rey: eu whole body mwcle 102 100 . 77 90 151 59 26-4 i 10*2 9* ,37 3*2 43 : 91 0-098 T 10-0 1-0 13 13-6 3-3 3*3 270 values in Table I can be used lo show (he differences in tissue distribution. The same authors24 determined chlorinated hydrocarbon residues in breeding pelicans end cormorants tn lakes to the north-west of the Great Lakes (Table It). 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 difference* in terms of rates of excretion of organochlorines into the eggs may be involved. Birds have also Table U - Chlorinated hydrocarbon residues in pelicans and cormorants pp'0D PCB D0EIPCB Em p.p.m. p.p.m. ratio Cormorant Pelican Fish (whole) 10-4 17 008 8 06 05 13 29 0 16 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 III). Secondly; the eggs from marine birds from two colonies widely separated from one another demonstrates vary convincingly (Table IV) specific differences related to migration habits. The guillemot spends the longest time in TsMa TV Specific differences related to migration habits . DDTfPCB ratio St Abbs Head Guillemot RasorWH Shag Kittiwake 0*233 0 500 0625 0 666 GnNowmy 0*230 0-435 0-727 0-875 coastal waters, the Kittiwake the shortest time there, for breeding purposes only, and the Shag is essentially seden tary. The effect of health on relative and absolute levels is seen in die report by Bonner21 on seal pup deaths. (TableV). TaMt V Effect of chlorinated hydrocarbon levels on teal pap health Total DDT PCB DOTtKB p.p.m. p.p.m. rotor XJrer: Cornish 2-4 46 005 Northern (well Ted) 06 4 0*15 Northern (starving) 2*0 6 033 Blubber: Cornish 111 160 0*07 Northern (well fed) 98 34 029 Northern (starving) 18-1 48 0-38 TsMt III ' '' Habit mi migrationfactors effMbtg cMorimted hydrocteboa rrridm i User Bird Ham \ No samples (a) Terrestrial predators: , . tttfc !! partial migrant* ! migrants . (b) Pieshwetsr (mostly Matte and mostly barest' <c) Maries (: 73 *9 9 57 4 Mem p.pjn. 4*5 . 4-3 1-0 345 25 No samples 115 " 6 5 124 96 Mem ppjn. 1*7 20 1*0 4-7 4-0 HQNS 086^18 ,V Notrmbrt f97t I'brnmtr? iithl Industry tui One or (he most striking features of freshwater species is the extraordinarily high levetn in herons at the head of a food chain where up to 9Q0 p.p.m. have bqen found1' in British material. As the British heron is sedentary, occurs ncnrly 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 a/,1* came from the Midlands and South East so that nb dear pattern emerged. However, the age factor is 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 meoni 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 Ihe failure of Holden26 to find them in freshwater fish in Scotland, and by Davis31 who failed to find them in beetles, earthworms, slugs and grasshoppers of one agri cultural area in England. To what extent are PCBs found in human beinp and foodstuffs? Jensen in 1966 first reported? the presence of PCBs in human hair, and later reports12'*3 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. Recently a very extensive survey of foodstuffs In Sweden sampled between 1967 and 1969, and anatyicd for organochlorine pesticides and PCB't, has been published.1 In a wide range of foods and food materials, PCB levels were found to be below 0*1 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 fat content. Another case where relatively high levels were found was with milk. Cows excrete tittle DDT in their milk and here all eleven samples were below 0*03 p.p.m. DDT and 0*1 p.p.m. PCB on whole milk. In human milk relatively more DDT is excreted and the average over 22 samples was 0*l07j>.p.m. DDT and 0*16 p.p.m. PCB. Other relatively high lampta are eggs and butter. (Table VI) Tefels V] Human milk Em. Hk ButMr 7WW Mr DDT 22 0107 20 0 21 U 01 KB 0 16 0427 0-03 ! DDTIKB (p.p.m. whak MUtf) 0*664 7-71 3*33 Soon after the beginnings of Industrial uaa of the chlorinated naphthalenes and biphenyl early in this century, human exposure was seen to lead to skin, eruptions (chloracne) and in animal inhalation and feeding experiments (1919), it with the chlorinated human deaths, j gations were continued in the 1930s, and it w;is further demonstrated in work on rabbits that in the naphthalene series the higher chlorinated mixtures were the most toxic. The work was expanded by Bennett ct a!.,2-" who uko 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 Ihe lower ones, but that the PC B 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, e.g. carbon tetrachloride (used as a solvent for these mixtures), and much smaller doses than normal were rapidly fatal. Miller in 1944'* 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 !380mg (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 Oettingen in 19S533 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,56 reviewing the situation in 1939, concluded that there had probably been at least six human deaths from this cause. Bennett et a/.32 had measured the air concentration at thirty industrial plants and suggested a maximum allowable concentration (MAC) of 0*5mg/m3 for tetrachlorinated and higher chlorinated naphthalenes, with Ihe observation that these levels had certainly been grossly exceeded over the previous twenty years. This work resulted in increased awareness of the 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 195337 laid down an MAC for the lower chlorinated PCBsof I *0mg/m3, and for thehigherchlorinatedonesCArochlors' l254-)0-5mg/m'.This appears to presume parallelism with the naphthalenes, and these figures are perpetuated in handbooks of industrial toxicology,31 but recent papers2 45 point to the reverse situ ation (see below). These MACs are to becompsredwith those for `Aldrin' and `Dieldrin' (0`25mg/m\ tentative) and parathion (0* I mg/m2). The oxidised chlorinated Mphenylt are more toxic than the.parent compounds.3* McLaughlin in 1963 published the results of toxicological studies on a number of chemicals which might be found in food3* using a sophisticated method based on injection into fertile bens' eggs. 23,000 eggs were used over three years and strict controls set up. Among the compounds tested wss the MNS 086219 114.1 211 Norvniher I'I7I f lu itUMry nttii Imlmirv 'Arochlor 1242' injected at 0-025 and (Wml giving a 0 nod This 1*01) Inis about five times the capacity to reduce 5 per cent hatch as compared with over 95 per cent in the ocslradiot levels than DDT or DDE. The effect of a single control group. Teratogenic cfleets were also noted in some dose of DDT may last for over two months. This work of the chicks which did hatch. These results may he com wns extended to compare the effects of two different PCBs pared with those for `Hcptachlor*. where 0-05 and 0* 10ml of in kestrels, again using liver mtcrosome isolates.41 The a I per cent solution in propylene glycol (non-toxic) gave a kestrels were fed at 0*5 and 5*0 p.p.m. levels with 'Arochlor 75 and 65 per cent hatch respectively. 1254* and 'Arochlor 1262', and the results were as in Table Flick et of.49 endeavouring to identify the factor causing VIII. 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 TaMs vm Polar metabolites {tumles/g micrasamat oedema in chicks, investigated the effect of `Arochlor 1242'. Groups of twelve chicks were fed on diets containing *1254* *1262* 200 or 400 p.p.m. over a three week period, changes in Control 0 0 weight being noted. Weight gain was lower with the 400 p.p.m. diet and indeed loss took place at the end of the 0 5 p.p.m. 50 p.p.m. 13-65 60 5 1905 47 95 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 PCB produced simitar effects to the oedema factor, but was not so potent, and gas chromatography demonstrated that it was not the same. . Two groups of workers, Risebrough, Peakall et al. in the USir.J4.4i-i and Jefferies, Moore, Preset et al. in Greet Britain.1*.*4 have actively pursued the effects of organo- chlorine pesticides and PCBs on birds. The decline in certain bird populations, especially raptors, has been attributed to the presence of organchlorine pesticides, but it is also possible that PCBs have played a part in this, not only because of their intrinsic toxicity but because it has been shown (in insects,2 and below) that 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 shown14-4' that organochlorine pesticides at the order of one p.p.m. are effective in inducing steroid hydroxylases in avian liver, thus leading to lowered oestrogen levels and reduced reproductive capacity. Added to this DDE has nn entirely different effect on the reproductive system, that ofcausing eggshell fhinning, which causes added failures in reproduction. Teratogenic effects may also occur because of the excretion/eoncentration factor in the eggs. It is thus necessary to review the effects of the organo chlorine pesticides on birds in conjunction with those of the PCBs. Following work by Peakall,41 which demonstrated that pigeons fed with DDT at 10 p.p.m. and/or 'Dfeldrin' at 2 p.p.m. for one week had higher levels of testosterone or progesterone metabolites than controls, Risebrough, Peakall et of.1* compared the effect of DDE, DDT and PCB ('Arochlor 1262*) In increasing the levels of polar mctabol- ites in omtradiol metabolism, again using pigeon liver isolates in vitro. Their results are given in Table VIi. While these figures do not clearly indicate the relative activity of these PCBs, it has been shown that 'Dieldrin' and PCB are much more active in reducing oestrogen levels than either DDT or DDE.42 That pesticides reduce oestrogen levels in mammals has also been demonstrated. Prcsst, Jefferies and Moore44 investigated the lethal effects of 'Arochlor 1254* on Bengalese finches. Food containing higher levels ofPCB (440 p.p.m.) was refused by the birds (100 per cent mortality not occurring) but it was still possible to calculate the LD5n 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 there was a correlation betweendoserates and liver concentrations, there was also considerable varia tion in levels (3-697 p.p.m.). Whether a particular con centration will be fatal will depend, at with organochlorine pesticides, on the condition of an animal. Considerable storage in fat is possible and until thb reservoir is saturated, concentrations will probably not rise to lethal concentra tions in susceptible organs. So danger can arise in times 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/Uver percentage as ,,__ a useful index, being high in those birds that died (83 7 per cent and low in the survivors (26*4 per cent). The LD<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 steep (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 condude 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, TaMsVll ' rotor oktoboHtet feetmi (me mate) without riting evidence, that the PCBa do not vary markedly in toxicity and this is at variance with recent work^^fsee Control 29 - i below), the PCB used here being of relatively low toxicity. DDB (40*n|/kl) DDT(40me/ki) ret pOmg/ks) 76 t W( ISO ' Additionally the author* do not consider the possibility of synergistic effects.2 It was recognised that the position with suMethal effects may be different. HO NS Q66ZZQ ,*W Nawmlvt IV7I Chrntixiry ami huiaitry f 345 Very little work20.47 has been done on the effect of PCBs (and terphenyls) on aquatic organisms, despite the fact (hat it is known that some marine Crustacea and fish are very sensitive to organochlorine pesticide residues.44 For example Crnr.gon vulgaris (brown shrimp) has an LCj0/48h/ IVc for DDT of 0.00.1 -01 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 wnter and the difficulty of obtaining sufficiently stable emulsions.47'9 The use of solubilising agents, of low toxicity, overcomes this. Zitko,4* 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/J were lethal. Wildish4* using `Arochlor 1254' in emulsions, or solubilising with 'Corexit 7664', carried out 30d tests with Gammants ortonicus and found lethal threshold values of 0*001 to 00lmg/l (`Corexit') and 0*01 to 0-Img/l^ (emulsions). Guthrie et a!.41 tested mixtures containing chlorinated terphenyls and their oxidation products and found lethal threshold values of about 5mg/l and pertinently (hat low oxygen levels in the water enhanced the toxicity. Duke el ir/.* 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 ucutc toxicity tests and 20d bioassays. 48h teats on pinflsh 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 test and the effect was measured in terms of arrest of shell growth. Here I 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 a 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 are to organochlorine pesticides. Some toxicological work has been effected using insects.2*4* Moimrty2 dosed fourth iiistar nymphs of Chorthippus hrwmeus (grasshopper) topically with `Arochlor 1254' at 12*5, 50 or 200|ig levels, but found that definite mortality v*ss only associated with the 200pg group plus a possible s* b>lethal effect associated with moulting (fat mobilisation). The maximum amounts of PCB in individuals of the latter group were I4pg (male) and 8|ig (female/. The work of Lichtenstein, however, is much more revealing as to the relative toxicity of the various PCBs and the synergistic effects with DDT and `Dieldrin'. Groups of 50 Drosophila meiunogaMter were placed in contact with vessels coated with a layer of the substance or mixture of substances, and groups of IS Musca domestic* iwere dosed topically. Tests of the individual substances s towed that `Dieldrin* wes some 25-30 times more toxic th in DDT, and 1-8000 limes more toxic than the PCBs. T le higher chlorinated biphenyls, and the terphenyls, gave r se to no mortality in lb* V or 4lh Mi, but toxibtty Him ind with dmn in chlorine content in the lower half of (he series. These results raise doubts as to the relevance of fhc many papers which have used `Arochlor 1254', which here has little or no effect under these conditions. The synergistic effects with `Dictdrin* were positive with some of lower `Aroehlnrs* and uniformly positive with /yi'DDT up to `Arochlor 1254'. However, with the higher chlorinated PCBs and PCTs a reduction of toxicity was observed. While it is improper to 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 indication that consider able care should be taken in planning these toxicological studies. Work using mammals is equally sparse. A preliminary study by Sabotka,TM using `Arochlor 1254* and `Arochlor 1260' or DDT in single doses of 1-IOmg/kg (`Arochlor's) or 0-25mg/kg (DDT) carried out behaviour tests on mice over periods of 4 to 24h 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 Cedi45 surveying the oestrogenic activity of DDT analogues and PCBs in terms of the 18h glycogen response of immature ret 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 triphenylmethane compounds activity is restricted to those where either the pp' positions are vacant or filled by hydroxy or methoxy groups, being inactive where halogen or alkyl groups are present. So the pp' compounds perthane, Velthane, DDE, DDD and methoxychlor are inactive. However, pp'DDT is active and the op'isomer some sixteen times more so, while of the others mentioned only op'DDE gains a response. `Arochlor's 1221-48* are about half as active at pp'DDT, but the higher members are inactive, (cf. Lichtenstein). In perspective though these compounds only have something like 10'3 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 00 and /^ bi phenols have an equivalent oestrogenic activity. The lower chlorinated PCBs could be degraded in the atmosphere as has 2been 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 irradiation.51 At the same time it has been observed12,17,51 that the lower chlorinated PCBs tend to be absent in wildlife samples, particularly in birds, and it may be speculated to what degree there may be differential excretion or in vivo breakdown, and what effect this has. A recent study by Vos et a/.52 reveals another important aspect. They discov ered that two out of three 60 per cent chlorinated PCBs contained highly toxic oxygenated impurities. These two commercial preparations (`Phenochlor DP6\ `Clophen A60') when injected into hens' eggs at the 3*5mg level caused almost 100 per cent mortality whereas the third sample (`Arochlor 1260') gave a relatively tow mortality. A fraction containing no PCBs was isolated from one of them by 'FlorislT column chromatography and shown to ba toxic. MONS 066221 ha I 4 G;ts chromatography and muss spectra showed this fraction to contain fetrachloro and pcntachloro-dibcnzofurans which were, however, masked by hcxachloronaphlhalcne and hep* lachlorobiphenyl respectively, thus limiting the accuracy of quantification. The pcntachtorodibenzofuran was estimated to be nt about the 5 and 20 p.p.m. level in the two samples. That PCB exerted n similar effect to that of the chick oedema factor (CEF) had been noted previously,40 and that toxico logical studies using PCBs had produced variable results. I.2.3.7.K,y.-hexachtoro dibenzodioxin has now been identi fied as one of the oedema factors52 and it may be recalled that the toxic factor in the weedkiller 2,3,5-T was shown to be a letrnehloro dioxin.55 In fact these chlorinated dioxins and dibentofurans are very highly toxic~gfoups of compounds. 0 2mg pentachlorodibenzofuran is needed to cause 100 per cent mortality in hen eggs as compared to 0*05|Ag of hexachlorodibenzo-p-dioxin. The occurrence of the dibenzofurans in PCBi is associated with the use of sodium hydrox ide in the distillation of erode PCB. Pentachlorophenol (PCP) and 2,3,4,6- tetrachloropheno) are possible precursors of CEF and have been found to be present in toxic oleic acids.54 It is evident then that other compounds besides the PCBs themselves should be sought 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 are not readily available. Holden and MarsdanH have already noted the presence of unidentified polar compounds in wildlife extracts. U is fo ha hoped that the current FDA programme9* on the toxicology of PCBs takes into account all these factors. Analysis PCBs are extracted together with chlorinated hydrocarbon pesticides in routine residue analyses,97 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 ~ m fundamentally sounder, this ofcourse providing additional evidence of identity. Both thin layer chromatography and , ^column chromatography have afforded quite good partial m separation of PCBs from pesticides and the best scheme5* rclaim to leave only 'Aldan* with the PCBs, with which I there is very little interference by the PCBs. A number of I j workerai*'22'9*'** have confirmed the presence of PCBs I 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 PCBe is now adequately documented,2',*,,*,2*,9'*1 (and alio1,2,15,14,20, 34.2s.is.st) aftd on aon-polar columns the main region of interference of PCBe and organochlorine peetiddo residues with one another may vary from the point of emergence of 20 Nnvrmi'rr IV7I Chrtninry anti liuiuttry pp'DDE that of pp'DDT. PCBs may continue to emerge with retention times up to four or five times that of DOT It has been noted in this laboratory that response to PCBs relative to organochlorine pesticides can be small on some columns, and from the viewpoint of determining pesticide residues, can ameliorate the situation. However, using more polar columns, e.g. *QF-|* or 'XE-60V2,25,50,62 PCBs emerge largely prior to the DDT group, which allows simple quantification of the latter, but may still leave an unsatis factorily complex chromatogram. Improved resolution of PCB compounds has been claimed65 using novel stationary phases. One alternative has been to alter the retention lime of pesticides by derivatisation, leaving the PCBs intact, and of course aiding the identification of the pesticides. Jensen" used a mild nitration technique adapted from Erro ei ai and originating from the Schechter-Haller method, claimed that the PCBs remained unaltered while members of the DDT group were effectively removed, although other organocblorines {e.g. Toxaphene', heptachlor epoxide, lindane and BHQ are not removed. This scheme (1:1 HNOj/^SO* for Smin at 0c) was followed by Risebrough el e/.,f4,5 but Reynolds6* 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 potash15,14*30 leads to the dehydrochiorination of pp'DDT, pp'TDE, and 'Toxaphene', with the derivative peaks appearing earlier in the chromatogram, and the PCBs reportedly unaffected. BHC it destroyed by this procedure. PCBs have also been differentiated from DDT using carbon-skeleton chromato graphy.*6 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 reparations or organochlorine pesticides from PCBs and fractions can easily be obtained where only 'Aldrin'. 'Heptachlor'. and pp'DDE remain with the PCBs. The former two are not very important in respect of the gns 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 Mareden26'45 claimed good separation of PCBs using either alumina, silica gel, or both in series with long narrow columns. Reynolds*1 documented a separation with 'Florisil\ while Bevenuc and Ogata62 commented on their failure to reproduce this work in terms of pesticide reparations only, and noted the differences in activity between 'regular* and 'PR Floriair. This reviewer has found no difficulty in obtaining this separation using 'Floriair. Armour and Burke90 in a carefully documented paper showed that it was possible to carry out a separation leaving only `Akirin* with the PCBs. For this they used silicic add partly deacti vated with 3 par cent water mixed with celita and tiered the Ii HONS 0*6212 .V/ Ninrmbn IV7I ('hctnistry umi Industry 1347 .PCB* ('Arochlor's 1254 and 1260*) with petroleum ether. ' ArnclUor 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'DDE wilt emerge with the PCBs. Also, the separation is only possible provided that the column (20 I 5g) is not over loaded (re. not exceeding 20pg 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 chromntography/mass spectrometry,1*'22-'6*66 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 (i.e. in a column chromatography or gas chromatography effluent) and that the composition on a gas chromatography trace conforms lo that of a commercial mixture, then mkrocoulomctric estimation wilt give an answer. Jensen ft a/.,17 using u combination of mass spectrometry, ECCC and microcoulomelry obtained results which were only accurate lo 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 area19'59**3 or basing the calculation on one1,19*19 or more29 suitable peaks. pp'DDE or 'Dieldrin' may be used as an internal standard,i**29 One empirical approach calculated one PCB peak as />/>' DDT and multiplied by a factor of ten to obtain a result;24 another99 took the total area:weight ratio to be equivalent to that for DDE; end another ,9*J9 assumed the response of each peak to be equivalent to DDE end applied a correction factor from the uae of microcoulometric detection (the authors did not have permanent access to a microcoulometric detector). Gregory97 studying the electron copture coefficients of mono* and dichloro* and methyl* biphenyls showed that there is over a twentyfold variation between the chloro compounds. Zitko49 determined the concentrations of PCB in fresh and salt water by means of ultraviolet spectrophotometry and fluorescence. While the lower chlorinated PCBs can be prepared easily91 and only simple mixtures formed when using the Ullmann reaction, the higher members are more difficult to make singly. The decline of certain bird populations was associated with the use of'Dieldrin' 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 men 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 breading), tefltogenic and carcinogenic effects on both t)ie parent and later generations. LDji tests, even over a long jperiod, are irrelevant from this viewpoint. Certainly it is Itrue that severe 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 he set against this, however, is the finding (in Ll)<0 terms) that while with DDT there appears to be s 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 are 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 I p.p.m. over a long period, and in terms of muitigeneration 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-T53 and of mercury residues99 has recently come to the fore and they present tome 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 teratological as well as direct toxic effects due to traces of a chlorinated dibenzodioxin. It is as well that PCBs are not used in such fashion because it has now been shown that some commercial preparations contain traces of chlorinated dibenzofurans 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, but 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 farther 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 biithdy ignored. The ironic Htuatioo is of MQNS 086^23 I MR course thill the Kludge in commonly dumped in estuaries or even spread oul over the land *o that pollutants such ns the PCBa are recirculated through the food chains. These are hut a few aspects of environmental pollution which can ultimately lead to man's own detriment. In many cases the users of pollutant materials, industrial or domestic, have no conception of their own insidious contribution to pollution, and in the case of the very useful PCBs it is very difficult to see how their disposal can be controlled to minimise pollution. From the point ofviewofrestrictingtypes of use to those least likely to result in pollution, one prod ucer, Monsanto, has made a very responsible move7* 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 Ihe 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 mu himself that such searches are directed. I The author is grateful to the H. 1 Heinz Co. Ltd, for permission to publish this paper, j RiAmni 1 i WcaNIft G , Morin, K. ft Andermon, M., Ym Fddt, 1970,10 > Lichtenstein, E. P.Schul*. K. R,, Fuhrnnaan, T. W. ft Liang, T. T., J. eemt. fitf., 1969, 6ft 761 I * Kocman, J. M. ft GenderenjH. van, J. AggL Eed., 196ft 3(Soppf). 99 ' < Harrison, ft. 0.. J. Set. Fd Agrk., 1966,17,10 * ftobum, J., Amdyst, Loud., 196$, 96,467 * Walker, C. H., HmiHon, O. A. ft Harrison, ft. J. Sd. M Agrk,, 1967, II, 123 ' Anon., New Scient., 1966, 612 * Schmidt, H. ft Schultz, O., Am. 1SI1. Ml, 331 * Pennine, C. H.. hot. Eng. Chrm., 1930,22,1IS0 is Anon., Technical Bulletin O-FF/I, The "ArocMor" polychlorinated potyphimyb', Monsanto ii Bailey, S., Ounyan, P. J. A Fbhwick, P. B., Cbm. ft tod., 1970,70S ii Holmes, D. C, Simmons, J. H. ft Tatum, 1. 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