Document gk1bp5p4wLGqdDomjNzeMygG

43 te -. Tl.-c V:C rcmt.lr cd deep for vtvcrrd thf' ;ir.d year'', and ,i;r;v even ii ;vc r-.cr:T>v.cd. Aheu! 5,500 i ch:-r. >c in the hvdroloe.c env iro'.rr.or.! ir, reiluctcd in ar. ir,cre_/j in carbonate preduernn and the eventual coruvcr.ing of bottom sediments, culm inating in the dupoiili.m of '.hallow facies at 3,!00 i.t*. A t 3,100 it? water level rose sliniitly and th.cn fell again, main taining this low position until about 2,000 ;si*. Trees found in positions of growth near and below present water level and dated at 1,500 b p (N-390) v.etc submerged by ri ,:m; v.atcis at this time. The trees belong to he last period v.l.en water level was below that of today. The lake ro>c and remained deep until after European settlement. In the late nineteenth century it began to fail and in 1969 stood at its lowest level l'cr the pad I, 9!>D >r. In nearby Lake Gnotuk, submerged trees have been dated at J, 855S5 bp (GX-0149, E. D. Gill, personal communication). Synchronous oscillations in lakes 20 km apart provide strong evidence that the controlling factor was ciimate rather than local hydrologic variations. Furthermore, the major drying between IS,COO and 15,060 b p is in close agreement with evidence documented from lakes in different hydrologic settings in north Victoria a.r.d south-west New South Wales recorded by J. M. B.3. The rise at about 10.C00 b p , reflecting an increase in precipitation or decrease in temperature, cannot yet be correlated accurately with events elsewhere in Australia, although Kershaw4 suggests a wet period in north Queensland at this time. . Effects of a Post-Glacial thermal maximum are weakly represented by a slow full in water level and a corresponding rise in carbonate production from 5,5CO to 3 ,ICO bp. The magnitude and implied rates of these changes suggest conditions little different from those in the area today. The data therefore do not support the hypptiicsis of widespread Post-Glacial aridity so widely claimed in A ustralia' Although temper atures from 5,500 to 3, ICO p.b may have been slightly higher than in the preceding inlet vai, the degree of aiidny would almost certainly not have been siiificient to cafise the vegetation destruction and widespread ^landscape instability which arc sometimes attributed to events,of this time. \ Conditions moderated at 3 ,ICO bp when a'slight rise of lake level occurred, but the major rise marking thet beginning of the next relatively wet period did not occur until 1,900 b p. Oscillations in Lake Kcilambete can be matched in other lakes in a variety of settings in south-east Australia supporting the interpretations of the water level changes discussed here. The sequence of palaeoclimatic conditions probaeiy has general application through south-east Australia and; it may help provide a reliable basis for climatic correlations within Australia and between ditferent continents in both hemispheres. We thank Mr J. N. Jennings and l\!r C. D. Oilier who read and criticized the manuscript, and uMr Keith Mitchell fbr crawing the figures. . \\ \ J. M. Bowler Department o f Biogeography and Geomorpho'ogy, \ Australian National University, \ \ Canberra, A C T \\ \ T a is l ji K am ada Institute o f Physical and Chemical Research. Yantato-Machi Saitama Prefecture, \ Japan \ \ 1 \ Received June 1-1, 1971. \ 1 Yamasaki, F,, HamaJa. T., and llam ada, C., Radiocarbon, 12,559 (1970). * Polach, II. A., b ev erin i, J. F., and Bowler, J. M ., Rcuiiocarboit, 12, 1 (1970). * 1 Bowler, J. M., in AS.iriein.il .Mart and environment at Australia (edit, by Mchancy, 1). J , and GoLsan. J.), 47 (Australian National C'mvcrv.ty, 1971). * Kershaw, A. 1'.. A-1Piotai.. 9, 7S5 (1970). * Brown, \V. h ,, Ptoc. I ; t:. A.V. AVv South Wales, 70, 5 (1945). 4 Oow nes, R. C i. . t J . Aerie. R et.. 5, 443 (1454). 7 Gill. F:. D,, Austral. J. Set., 17. 204 (1955t A sbestos F ibres J l overages A a n d D r i n b i s ,r , 55/ . >r :N - v / /A - rf r> J ) '' Tin. 1lazards c f iriir.ling asbestos fibres' "4, the high ir eidcnce of ga strointc din'd c.sneer1,2,1" 7 ar,d abdominal r.ccp !as"ns3,s,, amor. g c 'tu ; v.r.t6 t.t> ar.d the fast that as! i'tcs may per.!.::rate the rm.cc SI of the 'ornach and the in teotme of cn;m::!;n -n arc kn own and so it is important to study the dhtri! vuticn of ashes'.os fibres in the environment. A .restos fibres have already t.:-:n found in lecer12, and the occ.rrrcr.ce of fibres 0.5 nm in Ieri;eth and 0 0! r.rn in diameter sue rests that such material muy tv r . i its way t-.rough filtering systerns into city d rinking water supplies, and this we have been able to confirm. ! C-bpin 1-- -------i : j Fig. 1 Electron micrograph of asbestos fibre isolated from beer (enlarged 31,000 times). The asbestos fibres in 400 ml. samples of beverages and water were concentrated by centrifuging in excess o f 16,000?, drying at 100' C and ashing at 500' C 12. The ash was taken up in 1 ml. of distilled water ar.d agitated in an ultrasonic \ ibrator to disperse the fibres and ash particles12. Five p.I. of this disper sion was evaporated with the aid of a heat lamp on ICO or 400 mesh -carbon coated copper grids. Using a Siemens Ehniscop IA electron microscope at SO kV and a magnification of 20,(160. the number of fibres in each of five or ten grid holes was counted, and corrected for dilution. Precautions were taken to prevent contamination of samples from extraneous airborne fibres and no fibres were detected in distilled water Table 1 Asbestos Fibres in Beverages and Water Sample Source * Beer Beer Beer Beer Sherry Sherry Sherry Port Vermouth Vermouth Soft drink Soft ihv.k Soli Soft drink Tap water Tap water Tap water U1) Tap water Tap water Tap water Tap water Melted snow River water Canadian 1 Canadian 2 USA I -- USA 2 Canadian Spanish - South African Canadian French Ii.ibnn G iver ale Tome water I Tome water 11 Chance Ottawa, Ottawa river (F) Toronto, Lake Cntar.o (F) Montreal. St 1uw.ocoe river(F) i ..... v.. . . . . . . s- ............. Beauporr, Quebec. St Lawrence river (i> kra below Quebec Ciiv) (NF) Drurrreor.Jv iltc. Eastern Townships, Quebec. St Francois river (F) Asbestos, Eastern Townships, Quebec, Nuclei river lb) Thefor.I Mines, w t.-in Townships, Qt.e.oe, l ae la fruite (NF) Ottawa, top JO cm (2-3 weeks pree.pitation) Ottawa river, at Ottawa No. of fibres x 10s I.- * 4.3 6.6 2.0 1.1 4.1 2.0 2.6 2.1 1.8 11.7 12.2 1.7 1.7 2.5 2.0 4.4 24 jo S.l 2.9 5.9 172.7 33.5 9.5 * I-, Filtration plant used, NF. no filtration plant used. NAl .Ut i t -VOL. 2r. JULY 3 197T Fig. 2 X-ray (Traction pattern of asbestos fibre shown in Fig. 1. 333 1 Mjik' im ', T. E., an miter, E. J., Areh. Eminem. Hecltk, 6, riO (1963). J SchkofT, I. J., Cimi i>. J.. and Hammond, E. C., J. Am er. \fc.f. Assoc., IKS, 142 (Ph-lV Horn,duine. IV O . .V)' ,4c.:.:. Sri.. 132. 647 (1955). * W erner. J. C-, Ann. .V) ,-t.v. 5.-:.. 132. 575 (1SV-5V L'rV'tin'C. I'. L., and Kendrick, M. A ., Arck. m ira i, Health, 15, 1S1 (Nt,7). * Kr.av, 3. E., 1lolmcy S., Doll, R-, and Hill, I. D., Dii:. J. Jndust. Med., 25. 293 (1965). 7 New bouse, M. L., and Wacner, J. C-. Brit.J. Induit. McJ.,26, 302 Q9M). ' * Kc.'.l, E. E.; Lancet, ii. 1211 (1960V 7 Hvxon, K. E'. \V,, D-it. J. Dis. C.nest, 59. 121 (1965V 10 Smith \V. E., Miller. L., Eisasscr. R. E., and Hubert, D. D., Am . \ r Acad. Sci., 152. 45o (lff'fV ** Westlake. G. E., Spjut, H. J., and Smith, M. N., Lab. Invest., 14, 2029 (1965). 11 Biles, B., and Emerson, T. R., Sature, 219, 93 (I96S). blanks which were treated in the same manner as the liquid samples. Twelve brands of Canadian beer, wine, sherry and port, six o f American beer, six o f Eutopean wine, \erm outh and sherry and two of South African sherry were examined and all were found to contain asbestos fibres. Counts made on some of these brands are-reported in Table 1. The fibres in Canadian beer (Fi;t. 1), sherry and water were identiiied as being chryso- tile asbestos by comparing their electron diffraction pattern (Fig. 2) with that of pure chrvsetils asbestos. Some of the European samples contained fibres o f amphibolc asbestos. Many asbestos fibres were hidden in clumps of debris such as mineral m atter ir. water and diatomaceous earth which is used as a filtering aid in beer. As a result, the number of fibres reported in Table 1 must be considered a minimum estimate cf those actually present. Most c f the fibres found in Canadian beer and in filtered city water weie less than 1 pm in length while most samples of wine, some American beer ana uniittcred melted snow or river water also contained a considerable number of asbestos fibres ranging from 1 to 15 pm in length. Tap water from three major Canadian cities, Ottawa, Toronto and Montreal, combined from 2.0 to 4.4 million fibres per litre. All of these cities h a\e filtration systems and Ottawa tap water, drawn from the Ottawa riser, had considerably fewer fibres than unfiitcred river water. Many cf Canada's major asbestos m;: ?s are located in the Eastern Townships of Quebec and filtered tap water from towns m this area did not differ greatly from that in the larger cities but unfifiered tap water in Thetford Mines, drawn from a small lake in the heart of an asbestos mining area, was exceptionally high in fibre content. The high lex ;i c f asbestos fibres in melted snow in the Ottawa area gives some indication of one source of asbestos in surface waters. The question as to the hazard c f orally ingested asbestos has ro:i yet been rcHclvCxi. The a m ' ur.'.s by weight of the j'::est os found in t:.j were exseed rely small--abs .t i l:5 P^*r 10 mii[lion brc---o.?*ffred from cour.::s on 1 mg sar .r les of f.b.re5 of ap;eroximitc.!y the same size as these four.d i the b e - .eraic.es ard v. atr. Further work is required to d[etcrrr.rr.e the*CXILent to v. h:ch :h? fibres penetrate t]sc walls cf the d :=' Irz ct. the c7-: tO V. r. eh t ' r . r- v r e tr? ---'ri'ted If. o trer organs of t:. e Lozy ?r.G the biolog.cai c:beets cf tr.e.r ic*. ^ence in various tissues. Studies of this rature are now in progress. We lhar.k Mr D. Campbell and Mr G. Bergeron for technical assistance and the Food and Drug Directorate, Department cf National Health and V.'elfare, Ottawa, for obtaining tnc water samples. H. M. C uvs:-. gham R. POK'iFKACT Food and Dru;; Directorate, Department o f Health and Welfare, Ottawa BIOLOGICAL SCIENCES Molecular Conformation of Deoxyuridine . T he structure determination o f deoxyuridine was undertaken as port of a series of conformational studies o f nucleic acid components. Such studies give information about the preferred conformation of nucleosides and nucleotides1-2, and may clarify the conformational differences and changes that occur in nucleic acids. The conformational parameters of interest in deoxyuridine arc the pucker of the sugar ring, the torsion angle of the sugar relative to the base about the elycosidic bond and the orientation of the C (5')-0(5') bond about the C(4')-C(5') bond. \ . \ In ribose and deoxyribose nucleosides, the most common type of pucker of the sugar is either C(2') endo or C(3') endo. In the deoxynuclcosides the C(2') endo pucker is by far the most common. Since or.e of the nucleosides with a C(3') exo pucker is thymidine3' it was o f particular interest to know whether deoxyuridine would also have this type of pucker. Even the same nucleoside in different environments can base a different type of pucker1, but these differences have only been observed in ribose nucleosides. There is therefore a need for further studies of deoxy nucleosides and nucleotides. Crystals of deoxyuridine were obtained from aqueous solu- tions. The unit cell is monoclinic with dimensions a = 7.91 A. 6 = 6.7 1 , c ==18.77 A, P = 96.6s a:nd the space group is P 2 ,, There are fou r molecu les in the unit cell and therefor e two m ol:.' u'es in t):e asym.it etric LT.it. Intensity data were cc;acted with a Hilgara r.d Watts linear dittractometer using rr.oly ecenum K a re diation. The structure was solved by Patterson inter- pretanion methods. The; first step v. as the determination. of the oner ntlon cf live p o re of the pyrFnid.re bases in the ur cell using the 1((V- ) t to n of Tc !!m and C cehm rr. 1 he ori. r of the P;- riuridine be e \ :r.il the p'sr ^ v. as cetcr- by mea.ns of a rc : ation furati'o.-ff, and the portions o: the m o'.-:cules rela tive to tv : 2, axis we; e found using the O' X ,Z 0) fermi.on of Tc'libi7. Fu 1 detads of the structure deterrr:ll::cn - u, ' \ *c,rf% T y r- R f;--;-or at t'-e r'"e=er' *, e c f ref; cement is 0.03. Thc conformation of both molecules in the asymmetric unit is very similar. Ti e pucker of both sugars is C(2`) endo, or C(2'J c n d o - 0 3 ') ex.o with respect to the thrcc-atcm plane C(H> Ofl'F-CM '). Displacements of the C (2'j atoms m mole cule: 1 and II rc'alivc to this plane are O.iffi a rd 0.335 A respectively, er.d of atom s C O ') they are O .ili and 0.210 A respectively. Thus the sugar pucker in deoxyuridine is hkc Plant in the majority of deo/.y nucleosides and differs from that in thymidine. Ti c plycosidic torsion ancle, <pc *-, defined by Dono.'i.c an d " T V . i < --S ' n mnU-mih: I am i --24" in r -/1:: ff ' II. 976 JOURNAL OF THE AOAC (Vol. 56, No. 4, 1973) SYMPOSIUM ON INDUSTRIAL CHEMICALS AS FOOD CONTAMINANTS Asbestos Fibers in Beverages, Drinking Water, and T issues: Their Passage Through the Intestinal Wall and Movement Through the Body HUGH M. CUNNINGHAM andR O D ER IC D. PONTEFRACT Food Research Laboratories, Health Protection Branch, Department of National Health and Welfare, Tunney's Pasture, Ottawa, Ontario, Canada K l A 0L2 M eth ods were developed u sin g an electron m icroscope to isolate and c o u n t asb estos fibers in liq u id s and tissu es. Fibers w ere d etected in beer, sherry, port, verm outh, soft drinks, and city drinking w ater at levels generally ranging from 1 to 11 m illio n p er lite r . R iver w a ter w as h igh er in asb estos fibers th a n w ater passed through a city filtration system , and m elted sn ow w as con sid erab ly h ig h er th a n river w ater. A sbestos fibers w ere a lso d etected in p arenteral solutions. D istribution studies on asbestos fibers ad m in istered to rats w ere perform ed w ith th e electron m icroscope and w ere su p plem ented w ith studies using both tritiated and neutron-activated asbestos. C rysotile fibers were in jected in to th e stom ach s o f rats a n d 2--4 d a y s la te r fib ers w e re is o la te d fr o m t h e blood , sp leen , liver, k id n ey, o m e n tu m , m u scle, lu n g, and brain. H igh est levels o f orally a d m in istered fibers w ere foun d in th e o m en tu m ; in traven ou sly in jected fibers resulted in h ig h est levels in th e liver and th e lu n g. Chrysotile asbestos is a greyish, fibrous mate rial composed of a specific crystalline form of magnesium silicate. The visible fibers are com posed of millions of submicroscopic fibers (some times called fibrils) about 200A in diameter ar ranged in bundles lying parallel to each other (Fig. 1). Upon extensive milling or abrasion the individual fibrils may be readily released from the bundles. Since asbestos has a crystalline struc ture, one of the best ways to identify it is by electron diffraction. The electron diffraction pat tern of chrysotile asbestos is shown in Fig 2. I t is well known th at in the mining and milling of asbestos the inhalation of fibers can cause can cer of the lungs and pleura. There is also con siderable evidence indicating a higher than nor mal incidence of gastrointestinal and peritoneal cancer in asbestos workers (1-5). Since asbestos js commonly used in the filtration of beverages, we decided to see if we could detect the presence of fibers in some beverages which are often passed through filters containing asbestos. A preliminary report was published on this work earlier (6). Experim ental The asbestos fibers in 400 ml samples of beverages or water were concentrated by centrifuging in excess of 16,000 g, drying at 100C, and ashing at 500C. This temperature could not be exceeded because it distorts the electron diffraction pattern. The ash was dissolved in 1 ml of distilled water and lightly ultrasonicated to disperse the asbestos fibers evenly throughout the water. Five gl was placed on a carboncoated electron microscope grid, the surface of which had previously been made hydrophilic by placing it in an ion flux to give it a positive charge. This allowed the asbestos-in-water suspension to spread and dry evenly over the surface of the grid. Five to 10 grid squares were scanned for each sample. Figure 3 shows some asbestos fibers that were found in beer; note the appearance of the typical central canal. The more time that fibers remain in water the more of their magnesium is leached out and the central canal begins to disappear. The electron diffraction pattern also begins to fade. We examined 12 samples of Canadian beer and wine, 6 of American beer, 6 sherrys and ports from other countries, and several local soft drinks. All were found to contain asbestos fibers. Those that we counted ranged from 1.1 to 12.2 million fibers per liter (mfl) (Table 1). Tap water in Ottarva contained 2.0 mfl and the Ottawa River from which it origi nated before filtration contained 9.5 mfl. Other large cities in Eastern Canada such as Toronto and Mon treal, which also use surface water, had similar levels of fibers. Unfiltered water from Hull, across the river from Ottawa, also contained 9.5 mfl, the same as de tected in the river water. Unfiltered St. Lawrence River water drawn at Beauport contained 8.1 mfl. It w'as surprising to find that two towns in the Eastern Townships (Drummondville and Asbestos), drawing CUNNINGHAM & PONTEFRACT: BIOLOGICAL ABSORPTION OF ASBESTOS FIBERS 977 F IG . 1-- A n a s b e s to s fib er a p p ro x im ate ly 4 /im lo ng sh o w in g how it Is c o m p o se d of a b u n d le o f fib rils a b o u t 200A In diam e te r. agat&'fat FIG. 2-- Electron diffraction pattorn of a chrysotile a sb e sto s fiber. ' ' \ 3) xi. i_____ 978 JOURNAL OF THE a o a c (Vol. 56, No. 4, 1973) FIG . 3-- Electron m icro gra p h of a s b e s to s fib e rs isolate d from be e r (e n large d 31,000 tim es). water from rivers that we thought might contain large amounts of asbestos, were not exceptionally high. However, unfiltered tap water from Thetford Mines, which came from a small lake in the asbestos mining area, was quite high (172..) mfl). Melted snow from outside our laboratories in Ottawa that had fallen during 2-3 weeks in March 1971 contained 33.5 mfl. This indicated that some of the asbestos was coming from the air; when we took a 24 hr air sample from outside our laboratory the day after a long rainy period, we found 545 fibers per liter of air. Most of the fibers found in Canadian beer and in filtered city watei were less than 1 pm long whereas most samples of wine, some American beer, and un filtered melted snow or river water and air also con tained a considerable number of asbestos fibers ranging from 1 to 15 pm long. To determine whether asbestos fibers consumed orally can pass through the wall of the intestine into the blood stream, we obtained a sample of very finely powdered chrysotile asbestos (7RF02, Johns-Manville Co., Asbestos, Quebec) and separated out fibeis of about the same size found in our beverages (0.5 2 pm long), using sedimentation in water (Fig. 4), as follows: 2.5 g asbestos was shaken in 500 ml of water in a graduated cylinder and allowed to settle for 30 min; the top 350 ml, which contained about 10% of the asbestos, was then drawn off. This contained 1 mg or 9.4 billion fibeis per ml. In order to administer this orally to rats and still insure that they did not inhale any of the fibers we could not feed it or give it by intubation, for some of the fibers might dry on their lips and be inhaled later. We therefore anaesthetized the rats, opened the abdomen, and injected the asbestos directly into the stomach. Two to 4 days later, uncontaminated blood was drawn from the orbital sinus by a capillaiv tube. The rats were then killed with an overdose of ether and were thoroughly vacuumed and washed with double distilled water and methanol to remove any fibers on their hair that might have come from their feces. Their abdomens were opened by covering their bodies with wet paper towels and then placing a new layer of wet towels in the incision after the skin had been penetrated. The major organs were removed and the brain was removed from the skull m the same manner. The tissues cannot be dried and ashed 1 LINE SHORT CUNNINGHAM <t PONTEFRACT: BIOLOGICAL ABSORPTION OF ASBESTOS FIBERS "A" Set 979 FIG . 4-- E le ctro n m icro gra p h of a s b e s to s fib e rs se parate d b y se d im e n ta tio n in water for u se in a n im a l expe rim e nts. W idth of field is 4 Mm. directly, for when the preparation is later viewed with an electron microscope the asbestos fibers are completely obscured by the mineral matter. The tissues were therefore solubilized with Soluene (Packard Instrument Co.), and the asbestos fibers were separated by centrifuging, washed with metha nol, and ashed at ,500C. R esults The results cf this experiment are shown in Table 2. There were 5 rats in each group. Those in group 2 were given 9.4 billion fibers and killed 2 days later; those in group 3 received 94 billion fibers and were killed 4 days later. No asbestos fibers were detected in the blood of the control rats but 4.65 million per g (mfg) were found m the second group. This would be about 0.1% of the dose present in the blood at that time in rats weighing about 60 g. Four days after treatment the level of asbestos in the blood declined to 1.19 mfg, even though these rats received 10 times as much asbestos. The omentum surrounding the small intestine appeared to take up the largest amounts of asbestos. The omentum consists part ly of peritoneum and partly of adipose tissue. It is therefore interesting to note that in women asbestos workers, Keal (7) found a higher inci dence of peritoneal cancer than of lung cancer. It is possible that the peritoneum may have a greater affinity for asbestos or else not be able to clear it as fast as other tissues. I t is also possible th at the omentum contained many small lymph nodes which could have filtered out the asbestos. The brain contained about 6 times more fibers than the controls, and the lung content was also appreciably higher. Unfortunately, counts could not be made on the livers or kidneys because of an excess of mineral m atter isolated with the asbes tos fibers. The amount of asbestos in the tissues of the control rats was rather surprising and we still do not know its exact source. The rats could not have obtained this much asbestos from their drinking water. We do not know how much was in their feed or air but the air would appear to be 4 I IN C C U rtD T ft 8* 980 JOURNAL OF THE AOAC (Voi. 56, No. 4, 1973) T a b le 1. A s b e s t o s fib e r s in b e v e ra g e s a n d w ater Sam ple Source" No. of fibers/ L, X 104 Beer Beer Beer Beer Sherry Sherry Sherry Port Verm outh Verm outh Soft drink Soft drink Soft drink Soft drink Tap water T ap water T ap water T ap water T ap water T ap water T a p 'w a te r T ap water M elted snow R iv e r water Canadian 1 C anadian 2 USA 1 USA 2 C a n a d ia n Sp anish South African C a n a d ia n French Italian G in ge r ale Tonic water 1 T o n ic w ater II O ran ge Ottawa, Ottawa R iver (F) Toronto, Lake O ntario (F) M ontreal, St. Law rence R iver (F) Hull, Quebec, Ottawa R iver (N F) Beauport, Quebec, St. Lawrence R iv e r (6 km below Q u e b e c C ity) (N F ) D rum m ondville, Eastern Tow nships, Quebec, St. F rancois River (F) A sbestos, Eastern Tow nships, Quebec, N icolet R iver (F) Thetford M in es, Eastern Tow nships, Q u e b e c , L a c a la T ru it e ( N F ) O ttaw a, to p 30 c m (2 -3 w e e k s p re c ip ita tio n ) Ottawa River, at Ottawa 4.3 6.6 2.0 1.1 4.1 2.0 2.6 2.1 1.8 11.7 12.2 1.7 1.7 2.5 2.0 4.4 2.4 9.5 8.1 2.9 5.9 172.7 33.5 9.5 " F, F iltration p la n t u s e d ; N F, n o filtration p la n t u se d . one of the most likely sources. We have analyzed the tissues of 3 humans who died of natural causes and found somewhat similar levels of 0.114-0.378 mfg in brain, 0-0.253 in spleen, and 0.773-0.915 in peritoneum. Most of the fibers were 0.2-2.0 /urn long, but one fiber found in the peritoneum of a rat was 15 fim long and one in the blood of another rat was 23.5 yum long. The asbes tos preparation with which the rats were dosed contained only a few fibers of this length, for most fibers over 20 um long were thicker than single fibrils and settled in less than 30 min when they were originally suspended in water. This raises the question of how the fibers were absorbed--by piercing the gut like a needle or by engulfment by pinocitosis. It is most likely th at a fiber 23 pm long passed through by piercing but it is difficult to explain how the shorter fibers passed. The ubiquitous presence of natural asbestos in the tissues of experimental animals and the te- This paper was presented a t the Symposium on Industrial Chemicals as Food C ontam inants a t the 80th A nnual M eeting of the AOAC, O ct. 9-12, 1972, at W ashington, D.C. T a b le 2. A sb e st o s fib e rs fo und after intragastric injection (m il!ions/g)a T issu e C o n tro ls Killed at 2 days (9.4 b illio n ad m in is te re d ) Killed at 4 days (94 billion ad m in is te re d ) B lo o d S p le e n Om entum H eart B ra in Lungs 0.00 2.33 2.46 2.09 0.05 1.06 4.65** 4.11 2.74 -- 0.31 1.80 1.19 3.45 18.25 2.28 0.29* 1.74 a = P < 0.05; * * = P < 0.01. dious job of counting the fibers with an electron microscope limit the usefulness of the technique used in the aforementioned animal experiments. For this reason, tritiated asbestos was prepared by a simplified modification of a technique de scribed by Turnock el al. (8) and neutron-acti vated asbestos by a technique similar to th at of Holmes and Morgan (9). To produce tritiated asbestos, 200 mg of asbes tos and 0.1 ml of tritiated water (5.77 mCi/ml) were sealed in a stainless steel bullet with an internal volume of 0.4 ml and heated in a muffle furnace at 375C for 1 week. Upon removal from the bullet the asbestos was dried for 3 hr at 138C. For neutron activation, 1 g of asbestos was irradiated at 10u neutrons/cm2/sec for 3 weeks and then allowed to stand for several weeks to permit decay of the short-lived isotopes. Com bined activity of all isotopes was measured with a gamma counter (Packard Instrument Co.) but best results were obtained with a multichannel analyzer with an attached computer by which the entire gamma ray spectrum was scanned and the individual peaks were identified and calcu lated. With the latter instrument, it was possible to distinguish between isotopes in tissues which had leached out of asbestos and intact asbestos fibers. Both tritiated and neutron-activated asbestos preparations were used to determine the tissue distribution of asbestos given orally and injected intravenously into rats. However, when given orally, much of the radioactive components of both preparations were leached out in the gastro intestinal tract, possibly because of the acid in the stomach. These soluble isotopes were then ab sorbed and became incorporated into the tissues to produce such high background levels that it was very difficult to determine the activity of the ONE LINE LONG CUNNINGHAM & PONTEFRACT: BIOLOGICAL ABSORPTION OF ASBESTOS FIBERS T a b le 3. D is t r ib u t io n o f in t r a v e n o u s ly in jecte d 3H -a sb e st o s in ra ts T a b le 4. D istrib u tio n of In tra v e n o u sly injected n eutron-activate d a sb e sto s In rats T issu e B lo o d B ra in Om entum Liver Heart K idney Lung S p le e n Per cent of dose/g A fte r 6 m in A fter 1 hr A fte r 24 h r 0.198 0.077 0.023 1.140 0.170 0.209 7.991 1.393 0.017 0.057 0.028 1.132 0.111 0.201 4.224 1.630 0.008 0 040 0.012 1.637 0.207 1.358 3.868 2.105 intact asbestos fibers even when the tissues were solubilized and subjected to extensive centri fuging and washing steps. The present experi ments indicate that small amounts of asbestos fibers pass through the walls of the intestine and concentrate in the peritoneum, liver, lungs, and other organs, but the levels detected are so small th a t further work is required to be sure of the exact amount. I t has been known for several years that asbes tos fibers may penetrate the mucosa of the stom ach and intestine of animals (10, 11) but pre viously no experiments had shown th at orally ingested fibers may pass completely across the walls of the gastrointestinal tract and enter the blood. Intravenously administered asbestos fibers are rapidly removed from the blood and most of them are deposited in the tissues within 6 min after injection (Table 3). At this time, highest levels are found in the lungs, liver, and spleen, but dur ing the next 24 hr the levels in the lung tend to fall and the levels in the liver, spleen, and muscle increase slightly. The omentum had the lowest of all tissues checked. When neutron-acti vated asbestos was injected intravenously into rats, recovery of the labeled components in the various organs and carcass 1 hr later was close to 100% and approximately 70% of the activity could be recovered in the asbestos fiber fraction when the tissues were solubilized and the fibers were centrifuged (Table 4). We have recently injected neutron-activated asbestos intravenously into rats on the 15th day of pregnancy and found considerable activity in the whole fetus and fetal liver. Up to 25% of the activity of the fetal liver could be isolated in the asbestos fraction by solubilization and centrifuga tion; it gave a spectral pattern similar to th at of neutron-activated asbestos standards. This is additional support for the hypothesis that the T issu e B lo o d B ra in Om entum Liver Heart K idney Lung S p le e n S k in Ca rcass Total Per cent of dose/g C e n tri fuged Total 0.12 0.11 0.10 3.91 0.34 0.41 8.06 3.72 -- -- 0.17 0.13 0.12 6.02 0.31 0.62 11.34 6.90 0.02 0.04 Per cent of d o s e / t is su e C entri fuged Total 1.13 0.18 0.16 43.89 0.31 0.82 12.29 2.20 -- -- 1.69 0.22 0.21 67.78 0.28 1.23 18.14 3.99 1.09 6.61 101.24 fibers cross other membranes such as the intesti nal wall. We do, however, plan to do further confirmatory work on this. In conclusion, we have presented techniques for isolating asbestos fibers from various bever ages, water, and tissues. We have also simplified techniques for producing and counting radio isotopic tracers. Results obtained by these tech niques indicate th at asbestos fibers are now ubiq uitous in our environment and can enter the body through numerous routes and distribute them selves throughout the various tissues. R eferences (1) Mancuso, T . F., & Coulter, E. J. (1963) Arch. Environ. Health 6, 210-226 (2) Selikoff, I. J., Churg, J., & Hammond, E. C. (1964) J. Amer. Med. Ass. 188, 142-145 (3) Enterline, P. E., & Kendrick, M. A. (1967) Arch. Environ. Health 15, 181-186 (4) Newhouse, M. L., & Wagner, J. C. (1969) Brit. J. Ind. Med. 26, 302-307 (5) Eimes, P. C., & Simpson, M. J. C. (1971) Brit. J. Ind. Med. 28, 226-236 (6) Cunningham, H. M., & Pontefract, R. (1971) Nature 232, 332-333 (7) Keal, E. E. (1960) Lancet ii, 1211-1216 (8) Turnock, A. C., Bryks, S., & Bertalanffy, F. D. (1971) Environ. Res. 4, 86-94 (9) Holmes, A., & Morgan, A. (1967) United King dom Atomic Energy Research Establishment, Harwell, England, Unclassified Rept. A.E.R.E.-R 5289 (10) Smith, W. E., Miller, L., Elssser, R. E., & Hubert, D. D. (1965) Ann. N.Y. Acad. Sei. 132, 456-488 (11) Westlake, G. E , Spjut, H. J., & Smith, M. N. (1965) Lab. Invest. 14, 2029-2033 ONE LINE LONG