Document pm2Jrpjgv8xJ9bKYO38k24KQ7

The polychlorobiphenyts, their occurrence and significance: a review by R. Edwards II. J. Heinz Co. Ltd, Hayes Park, Hayes, Middlesex Pollution of the plofyaj 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 fhort term toxic effects and long term ones (i.c. reproductive mjd carcinogenic effects), these latter being more difficult to |i$Less. The chlorinated hydrocarbons used as biocides arc vyell documented in their short term toxic-effects, and with knowledge of tiicir facile accumulation in the environment rluj: 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 enfry into the terrestrial environment arc through crop spraying and seed dressings with eon'sequenf accumulation in (hf soil. From (his point they can also reach the aerial environment secondarily by evaporation or 'co-distillation' and carriage in fine particulate matter. They are also systemic i'n plants to varying degrees. Aqueous run-off carries them through the drainage system together with industrial eP.luciU sources ro reach the marine environ ment above the continental shelves. It is thus possible for these compounds to rohejh the lower members of the many foodchuins. Mun'sdonieslicand industrial use of biocides for hygienic purposes lead? \o entry at various other points in the food chains. The ver'y large concentration factor (10-') possible in these loud chains is well known and in the final members (c.g. marine mammals, predatory birds, man) the concentrations can rpach alarming proportions, l.ipid solubility means that l^irge percentage of these residues will be stored in die f.ff depots of the body. The polychlorobiphgnyis (PCBs), with a very widely dispersed use throughout industry, have very similar pro perties to the chlorina(ccjl hydrocarbon pesticides, but arc even more thermally afid chemically stable. An important difference, however, liejt [n (he routes through which they contaminate the cnvirojvrjicnt. Emphasis here is on indust rial diluents reaching (|ie marine meJium,,Hnd possibly the binning of industrial wu'slf contributes relatively more to the aerial distribution. Ajtfjough recommended for use in conjunction with pesticides, there is no documented example of tins known to the uutnor, so dial distribution through crop spraying should ndt pc a contributory fuclor. This fits the known pattern of distribution of PCBs in the environ ment, the highest conccjttgAtions coming from the heads of fresh writer food dining, ^ltarine' organisms and sea birds. High levels urc also known in terrestrial avian predators, but only recently has it l>cen, shown' that in one region they can be found ut levels comparable to those for orgunochkwine pesticides. While relatively little toxicological work lifts been done on PCBs and some of the results are superficially conAiding, this can be explained and there can be no doubt that they have very similar effects on mammalian and avian metabolic processes to those of chlorinated pesticides, and indeed that synergblic effects can occur between the two classes.* If any control over the use of PCBs is ultimately attempted this will be much more difficult than with pesti cides because of the very large number of uses to which they arc put. There exists considerable difficulty in the analytical field because these compounds cannot be separated easily from pesticide residues, and this has probably resulted in quite a few reports in the past giving falsely high results for some pesticide residues.' Unknown peaks in gas chromatography analyses wtre early recognised4 * but it was not untit Jen sen1 applied mass sf>cctrom<ftry to the problem that some of them were identified as PCBs. ' Properties and uses The PCBs received early notice back in 18818 and were in widespread industrial use by 1930.9 The biphenyls, terphcnyls, naphthalenes, and mixtures of these arc chlorinated in varying degrees according to the use to which liicy arc . put,10 and are marketed under trade names sufh as `Arocltlor', 'Phcnochlor', and `Clophen'. The products arc complex mixtures of the various compounds and isomers. They range from mobile liquids to crystalline materials or hard resins, and while the lower members arc readily soluble in non polar solvents they become progressively less so w ith incrdtising extent of chlorination. They arc extremely stable com pounds, not hydrolysed by water, acid or'alkali, and with n thermal stability such that they are used In litc-proofmgfi They find use in elastomers, adhesives, painls'. varnishes, \ printing inks, putty and us general fillers. The excellent dielectric properties lead to widespread use fof electric insulators and ns coolant,insulators in transformers. This stability and their low vapour pressures make theV ileal as lubricants, hydraulic fluids, liquid seals, cutting (Jls ^irui vacuum diffusion pump oils. Employment in rni^aning materials has led to the contamination of fooiw*t Theic are a host of other uses, but finally it may be mentioned that both ilic Monsanto Company and the USDH have reported that they act as effective vapour suppressants in insecticide formulations and thus prolong the active life of an applica tion. However, it liar, not been acknowledged that PCBs have actually been used for this purpose commercially. As an ancillary fact, a patent for the production of PCBs from lindane residues lias been granted. This multiplicity of usage has repercussions in the analytical aie.t because $ , ' QSW 029342 STLCOPCB4013304 }0 ,\'nivmhit IV? I Chemistry and Industry many solvents, some adsorbents and oilier analytical niatciials. and even the almosjplicrc of a laboratory can be contaminated by PCBs. Occurrence In tlic environment ; It is now well established thai t'Clh cun be found in wild life in many ureas of the cnyironment.1 -ar> The hiphesl IcseK arc generally associated vjith the industrial areas and the adjacent freshwater atuji .-marine food chains. The distribution is inevitably not tjujte so simple as (his because of the migratory habits of soipc of the species involved19'2-1 and the fact of widespread aejrial distribution.-8 Cohen and Pinkerton-1 reviewed the lat,te|r in respect of pesticides, mainly over the North American continent, and found higher levels in dust than |ramfull. Risebrough et a! studied the carriage of pesticides in the trade winds coming from Europe and Africa by collecting dust front the air over the Barbados Islands, ajnjl detected from 1-64 p.p.b. organochlorine residues. Dust collected over the Californian coast contained some thousand times greater concentration of organochlorines. but nonc^ojdd be found in dust collected from over the Central Pacific, although traces woe infcried from the nature of the particulate matter. While no PCBs were detected in any of these (samples, it was concluded that they weie probably present in !(racc amounts. Tarrant and Tatlon,28 however, who fouqd organochlorine pesticides in rainwater samples taken frpnt all over the British Isles shoved that levels were highest in the summer months (</. ltisebrouph et ol.-) and it) populous areas, also found ITUs in all of them although they did not estimate the concentrations. The import^nbe of aerial distribution of pesticides relative to the hydroj-pheric distribution has been stressed by Risohrough et at., land it is inferred that PCBs have a similar pattern of disliibution. However, it would seem that with PCBs morf (emphasis should be placed on the hydrosphcric med^upt. because an important part in the transfer to the ^tipospherc, via dusts used as carriers in agricultural applications, can be considered as low in this case. If the vapour pressures of DD1 and PCBs arc taken as being of the iafne order, it would then be expected that atmospheric |cyels of PCBs would be low' iclaiivc to DDT. The relative) concentration of pesticides and PCBs in the Indrosphcrtf and atmosphere have yet to be convincingly cK-moitslrated. . The outstanding feature Of (the distribution is the occur rence in tnatine organisms o`n |th,e continental shelves round Noilh West Europe and 'jsjprlh America, and also the cxtiaordiuaril) high levels fpilml in some freshwater avian predators, all associated vfth diluent from industrial hciivity.*-'-*4-lfc**7--Alpim. the west coast of the USA PCBs have been detected ip (estuarine and coastal waters in San Francisco Bay. San tpiego Bay and Puget Sound (Washington). In areas remote from industrial activity round the Bay of California aiul parts or the l\mnma cqast for example, birds' eggs copijiincd 20-30ug PC'B each, but near the above mentioned industrial localiofis the oggk con tained up to several bundled and sometimes over a thousand pg PCB egg. 1 he east coast o( live USA has yielded similar ev idence for contamination hyl'CBx. Holden and Marsden1-1 detected PCBs in seals from the Gulf df St Lhwrenccihshal- :!i D4I lov,' voters (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 soulh, in the Gulf of Mexico, in estuarine waters at Charle ston, S. Carolina, levels of less than 01 p.p.m. were found in fish and blue crabs.20 Duke el a), also monitored the results of nn industrial leakage into the Fseambia River which was carried through several inner bays through to the Gulf of Mexico off Florida. Maximum levels at source ranged from 4iN(< p.p.m. in sediment to 20 p.p.m. in fish, Crustacea and sediment in the outei 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 of.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 Arcbi|vclago 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.ni. in white tailed eagles. The concentrations were equivalent to the total DDT levels found. Koemitn el a/.i6 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. 1 he uniformity of GC patterns suggested that they all originated from pollution of the Rhine. Holmes, Simmons and Tntton12 reported the pre sence of PCBs in marine birds and their eggs collected from round the British Isles, and Holden and Marsden1* showed them to be 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 ihnn in comparable northern samples (34-4K p.p.m.). but less than in East Anglian specimens (350-520 p.p.m.). Presst, Jefferies and Moore, surveying PCB levels in Biilish wildlife, reported an average of 4 (1-25) p.p.m. in the eggs of marine birds, and comparing the cast and west coasts of Scotland in respect of two sets of twenty five eggs somewhat higher levels (7 as against 3T> p.p.m.) in the western samples. No PCBs were detected in whales analysed by Wolman and Wilson,29 and this is compatible with a distribution pattern confined to the con'incnfal 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 inlo the food chains mainly via bottom living organisms. Most whales feed oi. plankton, and thus might in any case be expected to show low levels. A further point of perspective is also given by live fact that loss of lower PCBs from aqueous suspen sions when acralcd has been observed.49 Holden2" has traced aqueous pollution back to one type of source. 1 he work on seals in Scotland having shown that levels were highest in the Eirlh of Forth region, water samples from the surface and at depth from the estuary and river up to Glasgow showed no delectable amounts DSW 029343 STLCOPCB4013305 I >41 and only trace quantified in trunk sewer effluents, The jooplankton 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 w-ijtrks together with domestic sewage, and so the sludge, which i$ dumped olTshorc, was examined. The fiflcen sample.- analysed ranged from 1-185 p.p.m. PCB on dry weipht, w/itli two sewage plants giving con sistently high levels (50-If/) p.p.m.). Sludge from Manchester exhibited sohtcwhaf lotjve'r levels, and that from London less again, but taking Unto account the varying outputs, each area was estimated to contribute roughly I ton/ year PCB contamination to the marine environment from sewage sludge. In the pa^c of inland areas sludge can be disposed of by Spreading over the land surface, and so ofTer a route to terrestrial fo<j>d chains. The question of why it is that relatively low' lcvclf if PCB ore found in man and his domesticated animals, pbsjtd in 1967-' perhaps now has some answer. 1 Distribution in terrestrial and freshwater ecosystems has largely been assayed in jerms of the avifauna because of the effects of organochloripc pesticides and almost certainly PCBs on some bird populations. The DDT/PCB ratio has been used by Riscbrpulgh el ai. as an environmental index,14,24,23 but whet) data is compared consideration must be made of the various biological factors, such as tissue distribution, spgcies 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 uway to bccoirjc greater than 10 in remote regions. The geographical distribution in terrestrial and freshwater wildlife will be icsicwica within the framework of these factors. Risebrough cl i?/.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 showpd the highest levels. The maximum Table I Tisutc distiibutian of IWT goid PCB in peregrines amf their prev Total DOT DI P ' hDTH'CB p.p.m. p.p.m. ratio Pet egr ares: unhalchcd egg muscle liver body fat Prey: egg whole body muscle 102 100 77 50 151 59 26-4 102 98 57 3-2 45 9-8 0-098 too K> 1-3 15-6 3-3 55 270 T 20 November 1971 Chemistry and Industry values in Table I can be used to show the differences in tissue distribution. The same authors54 determined chlorinated hydrocarbon residues in breeding pelicans and cormorants in lakes to the north-west of the Great Lakes (Table It). As the birds used the same food sources the dear 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 rales of excretion of organochlorines into the eggs may be involved. Birds have also Table H CIiUh inated hydrocm t*i'n residues in (xticons amt cormonmt\ Xrp'DDE PCB DUEtPCB Eggs p.p.m. p.p.m. ratio Cormorant Pelican Fish (whole) 104 1-7 0-06 8 05 1> 29 0 16 been studied in Britain1--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 very convincingly (Table IV) specific differences related to migration habits. The guillemot spends (he longest time in Table IV S]H-ci/ic differences rcluted In migration habits , nnTIPCB ratio ' St Abbs Head Guillemot Rn/orbill Ming Killiwakc 0-233 0-500 0625 0-666 Galloway 0 2,so 0455 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 the report by Bonner51 on seal pup deaths. (1 able V). Table V Ejffect of chlorinated hukocarhon Irn'ls on seal pup hrahI1 ' ratal 0 nr pcb IWTiPCB p.p.m. p.p.m. taiio Liver: Cornish 2 4 46 0 05 Northern (well fed) 06 4 0 15 Northern (star ving) 20 6 0 BltibScr: Cornish III 160 0-07 Northern (well fed) 98 34 0 2v Northern (starving) 18 1 48 OR Table lit Bird class (b) Terrestrial prcd.uois: static partial migrants ' migrants ; (b) freshwater (mostly stal|c ^nd mostly herons) (cl Mrinc U\rr No samples 75 49 9 57 4 Mean p.p.m. 45 43 t-0 345 2-5 Egg No samples 115 ( 5 124 96 Mean p.p.m. 1-7 2-0 1-0 47 40 DSW 029344 11 STLCOPCB4013306 70 Novcntbcr 1971 Chemistry pod liidmliy > One of the most striking fgnjures 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 found'* 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 pood geographical index of ^CB distribution. Unfortun ately nearly all the samples obtained in the survey of Prcssl cl al.19 came from tW Midlands and South East so that no clear pattern emerged. However, the age factor is well illustrated by this species as the average liver levels for nestlings was found to bp 5 p.p.m, while that for adults was 98 p.p.m. Diet is of coufsc an important consideration, and means that different species from the same area can, exhibit very different PCD concentrations. Thus, while birds feeding on insects have slujiwjn 0-1 p.p.m. (liver), raptors feeding on mammals yielded 0-50 p.p.m. It is necessary then, when comparing or jnjerpreting data, to take into consideration all these factors. Terrestrial restriction of PCBs to near industrial 3reps would seem to be reinforced by the failure of Holden-6 jtoj find them in freshwater fish in Scotland, and by Davis*1, who failed to find them in beetles, earthworms, slugs iarid grasshoppers of one agri cultural area in England. To what extent are PCBs'found in human beings and foodstuffs? Jensen in 1966 fijrst reported7 the presence of PCBs in human hair, and lister reports15,23 indicated that levels in man and his foodstuffs were lower than those found in birds, and below 1 p.p.irj. One exceptional case has been recorded,55 however. Recently a very extensive survey of foodstuffs in Sweden sanipjed between 1967 and 1969, and analysed for organochfoj'ine pesticides and PCB's, has been published.1 In a wide range of foods apd food materials, PCB levels were found to be below d l p.p.m. (90 per cent of 1400 samples) and comparable jo1 DDT levels. The higher con centrations came from freshwater and marine fish, especially those with a high fat contept, Another case where relatively high levels were found wa,s with milk. Cows pxcr^te little DDT in their milk and hefe all eleven samples were below 0 0.? p.p.m. DDT and 0T p.'p.m. PCB on whole milk. In human milk relatively morp L3DT is excreted and the average over 22 samples was 0T07 p.p.m. DDT and 0T6 p.p.m. PCB. Other relatively high samples arc eggs and butter. (1 able VI) ' i, Human milk Egg, yolk Holler Total ' No DOT PCIt 77 O'107 ! 0 t6 70 0 21 0-027 17 0 1 003 DDTIPCB {p.p.m. whole materia/) 0-M8 7 78 3 33 Toxicology Soon after the beginnings pf industrial use of (he chlorinated naphthalenes and biphenyp early in this century, human exposure was seen to lejid to skin eruptions (chloracnc) and in animal inhalalion fin'd feeding experiments (1919), it was shown that liver damage occurred with the chlorinated naphthalenes. As a rcsulj tj>f thicc human deaths, investi 1)43 gations were continued in the 1930s, and it was 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 cl who 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 nits by inhalation, subcutaneous injection, and oral means, and it was confirmed that the high chlorinated naphthalenes were more toxic than the lower ones, but that the PCB was more toxic still. Here, feeding at a lower rate (0 05gTat 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 norma! were rapidly fatal. Miller in 194474 experimented with a PCB containing 42 per cent chlorine and worked on guinea pigs, rats and rabbits, using feeding, subcutaneous, skin and cornea! applications. He used single doses ranging from 69 to 690mg and courses totalling up to 1380nig (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 flic spleen. The occurrence of hyaline bodies in the liver was confined to the rat. Von Octlingen 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 Grccnburg,36 reviewing the situation in 19)9, concluded that there had probably been at least six human deaths from this cause. Bennett cl al.}1 had measured the air concentration at thirty industrial plants and suggested a maximum allowable concentration (MAC) of 0-5mg'm3 for tetrachlorinatcd 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 the hazards from vapours of these compounds and elementary improvements in industrial conditions has largely eliminated (his source of danger (but see Biros55). The American Conference of Government and Industrial Hygienists in 195?77 laid down an MAC for Die lower chlorinated PCBs of 1 0mg',m\andfor the higher chloiinalcd ones (`Arochlors' 1254-)0-5mg m'.This appears to presume parallelism with the naphthalenes, and these figures are pcipetuated in handbooks of industrial toxicology,38 but recent papers2,45 point to the reverse situ ation (sec below ). These MACs arc (o be compared w itli those for `Aldrin' and `Dieldrin* (O^Smg'ni7, tentative) and para- thion (OTmgmi7). The oxidised chlorinated biphenyls are more toxic than the parent compounds.58 McLaughlin in 1963 published the results of toxicological studies on a number of chemicals which might be found in food'* using a sophislicated method based on injection into fertile hens' eggs. 25,000 eggs were used over three years and strict controls set up. Among the compounds tested was the GSW 029345 I STLCOPCB4013307 1344 `Arochlor 12-12' initckcd at 0025 and 01ml giving a 0 and 5 per cent hatch ay compared with over 95 per Cent in the control group. 1 erotogenic effects were also noted in some of the chicks which ^id hatch. I hose results may be com pared \\ ith those fo) `iHeptach'or', w here 0 05 and 0- 10ml of a I per cent solution jin propylene ply col (non-toxic) gave a 75 and 65 per cent |lu}tch respectively. . . Flick t! ol.J0 endeavouring to identify the factor causing the chick oedema cjistase. following reports that the factor was highly chlorinatcjd and that a plasticiser (PCD) used as a cage wire coating tad at 0 01 per cent or higher caused oedema in chicks.^ Investigated the effect of 'Arochlor 1242'. Groups of tsyclye chicks were fed on diets containing 200 or 400 p.p.m. joker a three week period, changes in weight being noted. KVcight gain was lower with the 400 p.p.m. diet and indeed loss took place at the end of the period. Three chicky |an this diet died. Here the hydroperi cardium volume w>is ten times larger than with the 200 p.p.m. level or the controls, the pancreas, kidneys and adrenals affected. ahc| haemoglobin levels were lower. The PCB produced sirrjilar effects to the oedema factor, but was not so potent, ynd gs chromatography demonstrated that it was not the fatne. Two groups of wprf-ers, Risebrough. Peakall ft a!, in the USi4.3-i.4i- 3 and J^ffpries, Moore. Piesst rt a!, in Great Britain."-44 have Actively pursued the effects of orgnno- chlorinc pesticides alnd 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 ll^it PCBs have played a part in tiiis. not only because of thpir intrinsic toxicity but because it has been shown (in insets.2 and below) that there are synergistic effects between so)oj7 PCBs and DDT and 'Diddlin'. Lethal toxicity to the iidult bit d is not tiic only factor because it has been shown'-*-4,1 that organochlorine pesticides at the otder of one p.p.fn.1 are effective in inducing steroid hydroxylases in avia)t iiver, thus leading to lowered oestrogen levels and reduced reproductive capacity. Added to this DDF. has an entirely different effect on the reproductive system, that of causipii eggshell thinning, which causes added failures in reproducjichi. Teratogenic effects may also occur because of the excrction/concentration factor in the eggs. it is thus necessary jo review the effects of the organo- chloriuc pesticides on birds in conjunction with those of the PCBs. .; Following work by1 Peakall.41 which demonstrated that pigeons fed with DpT at 10 p.p.m. and/or 'Dicklrin' al 2 p.p.m. for one w^cj; had higher levels of testosterone or progesterone mctnbqiifes than controls. Risebrough. Peakall ft /." compared lit^c effect of DDF. DDT and PCB ('Arochlor 1262') in. increasing the levels of polar metabol ites in oeslradiol thelabolism, again using pigeon liver isolates in vitro. Ih^ir results arc given'in lablc VII. 1*t>k \ ti Coni lot DDt <40mp'kg) DDT (4Unu; Ig* PCB (20ms k(ft nwlvbaliies formed (/;/(i n*de\) 1 24 If : 93 |tW) ' _____ 4 20 November 1971 Chrmhny and lmbisn\ This PCB has about five times the capacity to reduce oeslradiol levels than DDT or DDF. The effect of a single tlose of DDT may last for over two months, this woik was extended to compare the effects of two diffetcnl PCBs in kesirels. again using liver microsome 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 Vill. Table VI!! Control 0-5 p.p.m. 5 0 p.p.m. fofar melahtibic.i (nmdeilg miriu.mntal fraction) `1254' 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 lex els 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 revised by the birds (100 per cent mortality not occurring) but it was still possible to calculate the LD$(| as 253-Omg/kg/d. Seven out of the 3R birds died. Fnlargcd kidneys was the main feature, will\.in two cases increased volume of peri cardial fluid. While there was a correlation betw een dose rates 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, as with organocliloiinc 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 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 n good index because the liver fat reserves may vary considerably and will themselves be mobilised ultimately. The authors thcrcfoie suggest (ho brain/liver percentage as a useful index, being high in those birds that died (K.V7 per cent and low in the survivors (26 4 per cent). The I.Dmi for DDT is some thirteen times lower than for thi-, PCB. but consideration has to be given to the fact that while the DD T mortality curve is sleep (no deaths at 1000 and all dead at !200mg/kg/d). the PCB curve is shallow, so that at low levels PCB may be more toxic than DDT . The autliois con clude on the basis of this experimental w ork, and teasonably assuming that no drastic change in useage of PC'B> 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 cv idcnce. that the PCBs do not vary mat kcdly in toxicity and this is at variance w ith recent work-'4;'-4(- (see below), the PCB used here being of relatively low toxicity. Additionally the authors do not consider the possibility of synergistic effects.-' It was recognised that the po-.ition with suhlcthal effects may be different. DSW 029346 STLCOPCB4013308 .}() NiiyuiiIh'i IV? I Cltcmittry aid! Inthnlry Very little work?"-41' v has tx^cn done on the effect of PCBs (and (erphcn)ls) on aquatic [organisms, despite the fact that it is known that some mnrj^tp Crustacea and fish are very sensitive to organoclilorific pesticide residues.44 For example ('ronton utl%aris (bfotvn shrimp) has an LCyoMSh/ 15 < for DDT of 0.00?- 0T p.p.nt.. and levels as low as 0-0001 p.p.ni. may be detrimental to some species of mollusc. One difficulty in tpe 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.47 Q The Os'e of solubiliunp agents, of low toxicity, overcomes this. Zilko,40 using`Corexit 7664' to solubilise 'Arochlor 1221' a(id `Arochlor 1254'. carried out 192 hour tests with these co^i^ounds using'Atlantic salmon parr. He found that concentrations above 2mg/I were lethal. Wildish41* usinp 'Arochlor I25<j` in emulsions, or solubilising with `Corexit 7664'. carried out 20d tests with Gammarus occanirus and found lethal threshold values of 0 00) to 0 01 nig/1 f Corexit') and D fH to OTmg/l (emulsions). Guthrie cl at,47 tested mixtures containing chlorinated lerphenyls and their oxidatjoji products and fouttd lethal threshold values of about 5mg/l and pertinently that low oxygen levels in the water gnhnnccd the toxicity. Duke cl rr/.J0 who monitored PCB levels in biota and sediment in the Fsenmbia Day area of Flprjda as a result of an industrial leakage of PCD into the F.scamhia River, conducled both acute toxicity tests and 20d blonssays. 48h tests ott pinfish and juvenile shrimps at the 100 p.p.b. level w;ts not toxic to the fish but caused 100 per pent mortality in the shrimps. Oysters received a 96h test pnd the effect was measured in teims of finest of shell groWth. Here l p.p.b. resulted in 19 per cent decrease in sin'll growth and 100 p.p.b. 100 |>ct cent. Resultant whole bqdv concentrations for the three oiganisms were 17. 3-9 mid 3.3 p.p.tn. respectively. It should be noted that the oysters whcji replaced in PC B free water for three weeks recovered (their normal growth rates, In the 20d assn)s using a conciliation 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 ciuxtnccu and mpllpscs are as sensitive to PCBs as they arc to oi panoehlorinc pesticides. Some toxicological work has been effected using insects.J-46 Moriarly- dosed fourth instnr nymphs of Chorihippus Iminneas (grasshopper) topically with `Arochlor 1254' at 1 ? 5, 50 or 20() ig levels, but |foimd that definite mortality was only associated with tl)e 2(X),jp group plus it possible sub-lethal effect associated wjitji moulting (fat mobilisation). The maximum amounts of {TB in individuals of the latter group were 14-rg (male) ntld Kpg (female). The work of Lichtenstein, however, is n)u{-'h more revealing as to the iclativc toxicity of the varjojis PCBs and the synergistic effects with DDT and *L>icl0rfn*. Groups of 50 Drosophila iiithinopasicr weie placed in.contact witii vessels coated with a layer of the substapcc or mixture of substances, and gioups of 15 Afmra dpmcstica XverC-dosed'Kopicatly. Texts of the individual substances showed that 'Dicldrin' was some 25-20 limes more; toxic than DDT, and 1-8000 times more toxic than the p(_'Bs. t he higher chlorinated biphenyls, and the terphenyis. gave rise to no mortality in the 24 or 4KI) tests, hut toxieijy increased with decrease in :^ i345 chlorine content in the lower half of the series. These results raise doubts as to the relevance of the many papers which have used `Arochlor 1254", which here has little or no effect under these conditions. The.synergistic effects with `Diel- drin' were positive with some of lower 'Arochlors' and uniformly positive with pp'DDT up (o 'Arochlor 1254'. However, with the higher chlorinated PCBs and PCls 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,50 using `Arochlor 1254' and `Arochlor 1260' or DDT in single doses of l-10mg/kg (`Aroehlor's) or 0-25mg/kg (DDT) carried out hehaviour 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 Bitmnn 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. T he stereochemical require ments are quite strict, and in general for diphenyl-methane and -ethane, and Iriphcnylmeth.ine compounds activity is restricted to those where either live pp' positions arc vacant or filled by hydtoxy or methoxy groups, being inactive where halogen or alky! groups are present. So the pp' compounds pcrlhnnc, kelthane, DDE, DDD and methoxy- chlor arc inactive. However, />/>'DDT is active and the u/>'isomer some sixteen times more so, while of the others mentioned only op'DDE gains a response. `Aroehlor's 1221-48' are about half ns active at pp'DDT, but the higher members a re inactive.fc/. Lichtenstein). In perspective though these compounds only have something like 10 ' times the activity of natural oeslrogcns, but this fits well with the observed pattern of steroid hydroxylase induction in birds, where DDT and PCB are very active but DDF. is less so. Perhaps another significant point is that the oo' and pp'bi- phenols 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 wheic PCBs on an aqueous surface were subject to VJV irradiation.51 At the same lime it lias been observed'?-'1 that the lower chlorinated PCBs (cml to be absent in wildlife' samples, particularly in birds, and it may be speculated to what degree there may be differential excretion or in xiu> breakdown, and what effect this has. A recent stud) by Vos cl al.-~ reveals another important aspect. They discov ered that I wo out of three 60 per cent chlorinated PCBs contained highly toxic oxygenated impurities. These two commercial preparations ('Phcnochlor DP6', `Clophcn A 60') when injected into hens' eggs at the 3-5mg level caused almost I0<' 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 TTorisiP column chromatography and shown Jo be toxic. ,,, DSW 029347 ` STLCOPCB4013309 D46 ' Gas chromatography artd mass spectra showed this fraction o contain (ctrachforo a|>d p^machlorf-dibenrofurons which were, however, masked by hexachloronaphlludcne and heptachlorobiphcnyl respectively, thus limiting the accuracy of quantification. The pcn^aj'hlorodibcnj'.ofuran was estimated to be at uboul the 5 and pO p.p.m. level in the two samples. That PCB exerted a similar effect to that of the chick oedema factor (Ct l J hud been noted previously/0 and that toxico logical studios using PCBs had produced variable results. l,2,3,7.8,9,-he\achloro dibenrodioxin has now been identi fied as one of the oedem'a (actors'- and it may be recalled that the toxic factor in the 'k'ebdkillcr 2,3,5-T was shown to be a tetrachloro dioxin,53 Ip jfact these chlorinated dioxins and dibetuofunms ate very highly toxic groups of compounds. 0-2pg pcnt.tdilorodibchj'pfuran is needed to cause 100 per cent mortality in hen ggs ns compared to 0 05pg of hexachlorodibcn/o-p-dioxirt. -The occurrence of the dibenxofurans in PCBs is associated with the use of sodium hydrox ide in the distillation eff cude PCB. Pcntachlorophenol (PCP)nncl 2,3.4,6- telri)chlorophenol are possible precursors of CEE and have beep (found to be present in toxic oleic acids.54 It is evident then fhajt pthcr compounds besides the PCBs themselves should be spiight for in wildlife and that indivi dual compounds as wall as commercial preparations should be used in toxicological studies Unfortunately the indivi dual PCB compounds a^c not readily available. Holden and Marsd^i^5 have already noted the presence of unidentified polar ojm pounds in wildlife extracts. It is to be hoped that the current EDA programme56 on the toxicology of PCBs Unices into account all these factors. Analysis PCBs ate extracted together with chlorinated hydrocarbon pesticides in routine rgsjdue analyses,57 and being complex mixtures of compounds'with GC retention times on non polar columns almost identical to a number of pesticides, notably or the DDE frpiip. present an analytical problem which is not completely soluble by gas chromatographic means alone. Chcmiejil conversion of the pesticides, leaving, the PCBs alinpst unchanged, provides a partial but not completely satisfactory solution, but group separation is fundamentally sounder, this ofcourse providing additional evidence of identity, plpth thin layer chromatography and column chromulcgntpliy have afforded quite good partial separation of PCBs ffom pesticides and the best scheme5-1* claims to leave only `Aldrin' with the PCBs, with which there is scry little interference by the PCBs. A number of workers1*---''56,60 h?\c confirmed the presence of PCBs in living tissues by n^eajts of moss spectrometry, but apail from this means the quantification of PCBs presents severe problems because cyf ;thc large numK-r of compounds involved and that the individual compounds are not readily available, so that mosjt authors have only been able to calculate approximate figures. Gas chromatography retention data for PCBs is now adequately documcntcy15,16,16,26,513,61 (and nlso1,5,13,1450, 2,jvw.>w| and on npij-polar columns the main region of interference of PCBs u(k! organochlorine pesticide residues with one another may Vary from the point of emergence of 20 Novcitil'cr 1971 Chrmitlry and Indnstiy />/>'DDE that of pp'DDT. PCBs may continue to emerge with retention times up to four or five times that of DDT. 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-I' or `XE-60',,->':>5-*,,-6j 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 time of pesticides by dcrivatisation, leaving the PCBs intact, and of course aiding the identification of the pesticides. Jensen50 used a mild nitration technique adapted from Erro et a!. and originating from the Schechter-Haller method, claimed that the PCBs remained unaltered while members of Ihe DDT group were effectively removed, although other organochlorines (e.g. `Toxaphene', hcptnchlor epoxide, lindane and BHC) are not removed. This scheme (1:1 HNOy/HySO* for 5min at (TO was followed by Risebrough et ah,14,50 but Reynolds61 found that DDT detivative 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 potash13,14,50 leads to the dchydrochlorinalion of pp'DDT, />;>'TDE, and Tdxaphcnc*, 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', `ilcptachlor', and pp`DDli 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 /y'DDE can emerge with the major PCB peaks using non-polar columns. Thin layer chroma!ogrupliy has given this sort of separation using silica gel15 and aluminu,1,5 and in column chromatography Holden and Marsdrn-6 45 claimed good separation of PCBs using either alumina, silica gel, or both in series with long narrow columns. Reynolds61 documented a separation with T'lori- sif, while Revenue and Ogata65 commented on their failure to reprcnUtcc this work in terms of pesticide separations only, and noted the differences in activity between 'regular' and 'PR Elorisif. This reviewer has found no difficulty in obtaining this separation using `Elorisif. Armour and Burke51* in n carefully documented paper showed that it was possible to carry out a sepurution leaving only 'Aldiin' with the PCBs. For this they used silicic acid partly deacti vated with 3 per cent water mixed with cclitc and eluted the OSW 029348 STLCOPCB4013310 20 November 1971 Chnniitry and Industry PCBs (`Arocbloi'x 1254 and 1260*) xvith petroleum ether, `Aroehlor 1254' needed the atWr volume of eluant and the reparation was move critical. ]Thc cautionary note is added that any trace of polar solvent in the sample will make the separation impossible and p/j'DDf will emerge with the PC'Us. Also, the separation ij only possible prov ided that the column (20 1 5g) is not over loaded (f.e. not exceeding 20yg PCH). This then solves the main separation problem leasing on non-polar gas chromatography coin nuts only it small PCB peak which nia)1 interfere v.ith the estimation of `Aldrtn'. These authors hnyc also documented the separ ation of chlorinated naphthalenes.6' . Confirmation of identity'hits been achieved b\ combined gas chromatography,.''mass Spectrometry.hut gener ally quantification is not simple because of the large number of compounds involved and because these are not readily available individually for |rc|fcrcnce purposes. If it can be assumed that a fraction (contains only PCBs (i.c. in a column chromatography dr gas chromatography effluent) and that the composition ion n gas chromatography trace conforms to that of a commercial mixture, then micro- coulomctric estimation wilj give an answer. Jensen et al.,11 using a combination of fnjiss spectrometry, TCGC and microcoulomelry obtained results which were only accurate to about a factor of two. Wjth the same assumptions electron capture detection can be uyeq, referring to commercial PCB mixtures-6 either by cstimqlijig the iota! peak nrca,v''v6-, or basing, the calculation oh |onc,,16 ,<J or more-0 suitable peaks. p/r'DDf or `Dicldfirt' may be used as an infernal standard.One empirical approach calculated one PCB peak ns pp'DDT and multiplied by a factor of leu to obtain a result;^ another66 took (l^c total arca:wcight ratio to be equivalent to that for DlVCj and another ,g-'" assumed the response of each peak to be equivalent to 1)1)1 and applied u correction factor froffi the use of microeonlomctric detection (the muhms slid dot have permanent access to h microcoulomclric deieclof).'Gregory61 studying the electron capture coefficients of )o to- and dichloro- ,,-md picthyl- biphen>ls showed, that tiigrp is oxer a twcntyfold variation between the chloro conjpptinds. /.itko,Q dctcrjmin^d the concentrations of PCB in f esh and salt water by means of ultraviolet spcciroplioton'ic ay and fluorescence. W'hile the lower chlorinated PCBs fa i be prepared casi1\('s and only simple mixtures formed wljcn using the Ullmann reaction, the highci members ar<- jnore difficult to make singly. Discusslorf ' .' 1 1 ', 'Hie decline of ceitain bird pbpulations was a-oocialfd with the us# of 'Diddlin' seed dressing-; and has been attributed to lew! toxic cflbcl.x. \Vifh increa.sing awareness of these ,dangr s, .better monitoring and uiiapc contiol. at least in dcvclopeo countries, let ml toxic tlVeets are progressively less like!) to occur. Rat ice. the significance <'f PCBs (and pesticides) to man and either orgurtkms 'must now l>e seen in the context of sub-1clh|il[c!Vce(s having long term influence on populations through flip media of reproductive pr<sccsses (reduction in fertility, delays in breeding), teiatogcnic and carcinogenic elleets on hC>th the parent and later generations. I.Djo tests, exon oxer a Uiijg period. arc irrelevant from this viewpoint. Certainly it `^s trie that severe martmialian 1347 liver damage and death can result from high PCB levels but these are only reached in a few foodchain heads, and the normal levels found in man are not of this order. To be set against this, however, is the finding (in LD<.0 terms) that while with DDT thege appears to be a definite `no effect' level this is apparently not true for PCB. Precisely what compounds are responsible for the toxicity of PCBs is not yet dear, 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 sonic 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 carr) out strictly controlled toxicological studies ill a feeding level of the order of 1 p.p.m. over a long period, and in terms of multigeneration 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 fix population hax'c been shown to result from heavy spraying programmes in these areas, and in the latter two Mates were tied to txvo specific forest spraying programmes. The pattern of these genetic changes can also be cot related with spread by winds over long dist ances. With PCBs the major dispersal medium is probably water, but otherwise thcr^arr no essential differences in the situation. The l'CBs arc spread all over the continental shelves which me fed by industrial effluents. The toxicology of the weedkiller 2,4,5-T'-' and of mercury residues6'' has leceiitly come to the fore and they piescnl some parallels with the PC'IK. While in conliaM 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 yd very little is known about Ibis area. Mercury, in contrast to PCB. is only cumulative in living tissue to a limited extent, and there is a definite natural contribution Bom the sea floor. The massive aerial use of the weedkiller 2,4,5-T as a defoliant by the Americans re-ultcd in leiatologira! us xxcll as diiect toxic effects due to traces of a chlorinated dibenzodioxin. It is as xxcll that PCBs arc nol used in such fashion because it has now been slioxvn that some commercial preparations contain traces of chlorinated dibcnzofuraiis which arc also highly toxic. Water pollution is rcecixing considerable attention within (ho traditional framework of oxygi a delieieney. reduced and oxidised nitrogen, temperature and so on, but the type of pollution problem presented by PC Its, DDT am! 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 xvaters, there appears to be a large conceptual gap. Commenting on the presence of DDT in raw sewage, (bis 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 of OSW 029349 STLCOPCB4013311 IJ4B . ., , 20 November 1971 Cllemishy and Industry course that the sludge is commonly dumped in estuaries or even spicad out over (lu,1, land so that pollutants such as the PC Us are recirculated through the food chains. These are hut n few aspects of environmental pollution which can ultimately le^d to man's own detriment. In many eases the usn.s of po!lut(in! materials, industrial or domestic, have no conception of their own insidious contribution to pollution, and in the ease of the very useful PCUs it is very diflicult U' see hose thejr disposal can he controlled to minimise pollution. Frohijlhc point ofvievs ofrestriclingtypes of use to those least likely to result in pollution, one prod ucer, Monsanto, has miictp a very responsible move70 in this direction, but as PCB manufacture is no longer covered by patents this may .not he clVcctivc. It is obvious that with their ubii|uitous presence ;thc effects of PCUs and associated compounds must be investigalcd with great thoroughness, it is not only to preserve bird populations or other wildlife but to present long ter|n changes in man himself that such searches are directed. 1 Hie author is giafcfyNo the H. J. Heinz Co. Ltd, for permission to publish this paper. References ' 1 Westbb, G., Norin, K. t Andc/sson, M., Car loda, 1970, 10 1 Lichtenstein, F. P.. Schulz, j<. R., Fuhremann,!, W. A Liang, T. T., J. econ. hit., 1969, 2, 7$ I, r Kocman, J. II. A Gendefep, H. van, J. Appl Lent., 1966, 3 (Suppk), 99 * Harrison, R. B., J. Sri. td .Agrie., 1966, 17, 10 * Roburn. J., Analyst, Land. 19o5, 90, 467 0 Wnlkcr, C. II., Hamilton, G. A. & Harrison, K. fl., J. Sri. I'd Agile., 1967, 18, 17? ; ' 7 Anon., New Srirnt., 1966, |il2 * Schmidt. 11. A Schultz, 0 , Ann. 1881, 207, 338 ^ . * Penning. C. 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J., (hganir Syntheses, I960, 49, 4t *7 Anon., hifiiriuation Bulletin, PlIIRA, 1970, 9, 2t2 7 Tinker, ]., New Scientist and Science Journal, April 1 1971, 16 DSW 0 2 9 3 5 0 STLCOPCB4013312