Document G62ML7pM3M4pOaqGReKGjdnG7

Environmental Health Perspectives Vol. 53, pp. 11-25,1983 | i PLAINTIFF'S EXHIBIT STO096949 Chronic Effects of Dietary Exposure to L Amosite and Chrysotile Asbestos in Syrian Golden Hamsters by Ernest E. McConnell,* Alan M. Shefner,* John H. Rust* and John A. Moore* Bloiwiyi of awMtl*. abort-rage (SR), intormarilaf* ring* (IS) or latorrodIto-rnge chryaotile aabaatoa in nombinotion with lb* iateatinaj carctnogan 1^-dlmetbyiliydrmrine dihydrochloride (DMBD wore oowfaotod with Bale and female Syrian g<Maa hamatora. Aaoaft* and both form* of chryaotile aabaatoa war* adwlniatarod at a conoantratioo of 1% in pelietad dial for the entire lifetime of the haautere starting with wothf* of the lent --Groop aim varied from Ut-Kt Thera waa no adreroe affect on body weight gain or survival by either type of aabaatoa or by IB chryaotile aabaatoa in combination with DMH. A aignlflcant incraaae (p < (LOS) in adrenal cortical tamore araa obeerved in mala hamatara exposed to SR and ZR chryaotile aabaatoa and in female* treated with IR chryaotile aabaatoa when compared to the pooled control groups. However, atatiatical significance <p < (LOS) waa loot wben thaee doaad groop* ware ooaparad with temporal control group*. Neither of the mala or female antdte aabaatoa gronpa (bowed increased peopletie in any tiaeoe or organ compared to the control group*. The cocarcinogan atodie* uaiag IR chryaotile aabaatoa and l^diaeathyihydraidna dihydrochloride were oonaidered inadaquat* bacauaa there waa no incraaae fat intestinal neoplasia in tha DMH group. Introduction In November 1973 the National Institute of Environmental Health Sciences and the Environ mental Protection Agency cosponsored a sympo sium on the possible biological effects of ingested asbestos (i). This conference concluded that a paucity of definitive data existed concerning the effects of ingested asbestos and that specific re search was needed. A subcommittee of the DHEW Committee to Coordinate Tbxicology and Related Programs was established to review existing data and to prepare a draft research protocol that would be responsive to the possible public health implication of in gested asbestos. This protocol was widely distrib- Natioua) Tbxicology Program, Nation*) Institute of Envi ronmental Health Science*, P.0. Box 12233, Research Thangle Park. NC 22700. tDT Ressarch Institute, Life Science* Research Division, 10 West 36th Street, Chicego, IL 60616. uted for comment within and outside the govern ment and a public meeting of the subcommittee was held on February II, 1975. On the basis of the comments received, a revised final protocol was developed which called for the use of long term animal toxicology studies to evaluate the ingestion of several minerals for carcinogenic ef fort. As a result the National Tbxicology Program investigated the carcinogenic potential of the in gestion of various forms of asbestos in rats and hamsters. All of the studies were to encompass the lifetime of the animal, including exposure of the dams frofn which the test animals were de rived. This report represents the results of studies undertaken to determine the effects of the inges tion of amosite and chrysotile (short- and inter mediate-range) asbestos in Syrian golden ham sters. The effects ofintermediate-range chrysotile asbestos in conjunction with a known intestinal carcinogen, 1,2-dimetbylhydrazine (DMH), were also studied. 12 UeCONNELL ET AL Hsblel. Fiber charnctariedcs of chryeotileaebeato*. Fiber rharartehetice Surface ares, mXg Density, (/cm1 Measurement, transmission tlectron microacopy Fiber oount/g Median length, pm Range of length, mb Masltaa dUUMtlf, jin Range of diameter, pm Median fiber aspect ratio (L/D) Frequency distribution by length (jun), optical microacopy 10 percentile 20 percentile 30 percentile 40 percentile 60 peroentile 60 percentile 70 percentile 80 percentile 90 percentile Short-range 5S.0 2.577 a 0.022 SD 0.6081 x 10D 0.66 0.068-51.1 0.059 0.019-1.57 11.1698 1.3 1.7 2.2 2.6 3.1 3.8 4.5 5.8 7.8 Intermediate-range 27.9 2.607 a 0.016 SD 0.1291 x 101? 0.82 0.104-783 0.089 0.019-11.5 8.435 1.4 1.9 3.0 64 14.0 29.0 48.0 76.0 130.0 Materials and Methods Asbestos is a general term applied to certain natural mineral silicates when they appear in a fibrous form. Chrysotile is the fibrous member of the serpentine mineral group while amosite is an amphibole mineral. Two chrysotile test materials were selected for testing and are referred to as short-range (SR) and intermediate-range OR) chrysotile. Intermediate-range chrysotile differs from short-range chrysotile in that the former contains fibers extending into relatively large sizes, both with respect to length and diameter. The short-range chrysotile was purchased from the Union Carbide Corporation, Niagara Falls, New York, which referred to the material as COF25. The chrysotile was mined from the New Idria serpentine mass located in the southwestern San Benito and western Fresno counties of California. Mineral and fiber characteristics of SR chrysotile are shown in Thbles 1 and 2. The intermediate-range chrysotile was pur chased from the Johns Manville Company, which referred to the material as Plastobest-20. The chrysotile was obtained from the Jeffrey Mine, Asbestos, Quebec, Canada. Mineral and fiber characteristics of IR chrysotile are shown in Ta bles 1 and 2. An amosite sample (S-33) from a mine in Psnge, Transvaal, Republic of South Africa was purchased by the Bureau of Mines from the Atlas Asbestos Company, Montreal, Quebec, Canada. The sample was processed by a single pass through an air jet mill to improve the homogene ity of the amosite. Mineral and fiber characteris tics of amosite are shown in Thblas 3-5. Ihble Z. Chemical-instrumental analyse* of chrysotile Content, wt--9 Short-range Intermediate-range AJ2O3 0.66 CaO 0.32 FejO, 2.02 MgO 40.62 K*0 Si03 Not detected 39.77 Ne,0 0.01 HO, 0.03 MaO 0.07 CtyO] 0.17 NiO 0.17 CojOj CO. 0.01 0.78 HjO 1.54 H*0* 12.69 Benaeae-extrected organic* 0.026 1.47 0.06 2.93 40.62 0.08 39.90 0.04 0.04 0.06 0.06 0.06 Not detected 0.51 1.17 12.81 0.011 The homogenidty of the samples and the physi cal and chemical properties of the materials were extensively characterized by the Bureau of Mines, U.S. Department of the Interior (Supt. of Documents No. I 28.23:8452) and by the Fine Particle Laboratories, Dlinois Institute of Tech nology Research Institute, Chicago, Illinois (Spe cial Report and Addendum on project L6085, con tract Nol-ES-5-3157). Copies of these reports are available upon request from the National Tbxicology Program. Tfest Diets The feed used was NTH-31 open formula rodent diet prepared by Zeigler Brothers, Inc., Gardner, EFFECTS IS HAMSTERS OF DIETARY EXPOSURE TO ASBESTOS 13 PA. The appropriate asbestos was incorporated to a level of 1% by weight into the test diet. All feed was pelleted with a Sprout-Waldron pelleter; the pellets were of oval configuration, s/a in. by 3U in. in size. Pelleted feed was packaged in 25-lb ali quots in standard paper feed-bags which were color coded to minimitp the occurrence of feeding Thble 3. Fiber characteristics of amosite asbestos Fiber characteristics Surface area, m'/g 4.13 Density, g/em* 3.36 s 0.026 SB Measurements, transmission electron microscopy Fiber count/g 0.3466 x 10" Median length, pm 4.37 Range oflength, pm 0.85-995 Median diameter, pm 0.72 Range ofdiameter, pm 0.064-12.4 Median fiber aspect ratio <UD) 6.4248 Thble 4. Chemical-instrumental asbestos of amosite asbestos. AljOj CaO FeO FejO, MgO K20 Si02 Na20 MnO Cr2Oj NiO CO, 0.42 0.48 34.61 2.24 6.22 0.30 50.36 0.03 2.66 0.03 0.01 0.88 0.15 errors at the test laboratory. Each lot of blended feed was analyzed for asbestos concentration. Sources and Specifications of Tfest Animals Four groups (three chrysotile and one amosite) of disease-free, mated female outbred Syrian golden hamsters were obtained over a period of 20 weeks in 1977 from Charles River Lakeview Lab oratories, New Field, NJ. The hamsters had been mated 6 days prior to shipping. Animal Maintenance Upon arrival, the mated female hamsters were weighed and sorted into weight ranges. They were then distributed randomly between control and treatment groups, which were housed in sep arate rooms. The first shipment of mated females was assigned to the short-range (SR) chrysotile study, the second to the intermediate-range (IR) chrysotile study, the third shipment to the IR chrysotile plus DMH study, the fourth group to the amosite study and their respective control groups. Each dam was placed in an individual cage with filter top in its respective"room. Control or formulated diets were provided ad libitum on the floor of each cage. Water was provided ad libitum via bottles. The hamsters were not han dled just before the litters were due to be born except when the cages were changed. Once the litters were born, they were left undisturbed until they were approximately 10 days of age. Then, the cages were changed weekly until the offspring Tbble 5. Particle sise distribution of amoeite aabeetoe by particle number: 8EM. Length interval, pro 0-1.99 2-3.99 4-5.99 6-7.99 8-9.99 10-19.99 20-39.99 Amosite mean width, pm. 0.28 0,38 0.45 0.45 0.48 0.52 0.51 Amosite particles per interval 57 126 83 78 52 181 184 Tbtal amosite particles, % 5.6 12.3 8.6 7.6 5.1 17.7 18.0 Cumulative amosite, % Amosite, vol.-St 5.6 17.9 26.5 34.1 392 56.9 74.9 - 0.1 0.3 0.4 0.4 2.4 5.0 Cumulative vol-% amosite - 0.1 0.4 0.8 1.2 3.6 8.6 Number of other particles 11 8 1 0 1 1 0 Amosite particles per length interval, 91 by aspect ratio: 1:1--2.9:1 12 0 0 0 0 0 0 3:1--4.9:1 6:1-9.9:1 34 10 6 5 2 0 0 43 52 23 14 4 1 1 10:1-19.9:1 11 34 52 38 40 21 1 20:1-49.9:1 0 4 18 41 54 64 30 50:1-99.9:1 0 0 1 2 0 12 55 100:1-199:1 0 -0 0 0 0 2 12 200:1-499:1 04000 0 1 >500:1 00000 0 0 Calculated from particle number data, assuming rectangular croaa aection with third dimension equal to Vs measured width. 14 UeCONNELL ST AL. were 4 weeks of age, at which time they were weaned. At weaning, the offspring were individually weighed and separated by sex. The test groups were randomly placed into groups of three males and three females and housed in polycarbonate cages for the remainder of the lifetime study. The dams were killed at this time. Twenty male and twenty female offspring were removed from the study for endo- and ectoparasite examination to confirm that the test groups were of a desired health status. Extra hamsters were not discarded at this time, in case animals had been missexed. Approximately 6 weeks after weaning, all mis sexed hamsters were killed along with their cage mates and were replaced with these alternates which had received maintenance identical to that received by the original hamsters. The remaining hamsters were killed. The experimental design insured that ingestion of asbestos spanned the entire phase of solid food consumption during the lifetime of the animal. Food consumption was not determined because of the hamster's habit of se questering its feed in the bedding. Control ham sters were housed in separate rooms. The number of animals in the study is shown in Ihble 6. Starting at 6 weeks of age, male and female hamsters in the intermediate-range chrysotile/ 1 ^-dimethylhydrazine dihydrochloride (DMH) study (Thble 1) were given oral doses of DMH (4 mg/kg) every other week for a total of 5 doses. The dose of DMH used in this study was based on the results of a pilot study carried out previously in the same facility. The latter was conducted in a manner similar to that reported in rats (2). The DMH (Aldrich Chemical Co., Milwaukee, WI) was used as received and was dissolved in 0.9% saline to a concentration of 1.5% (15 mg/mL). This stock solution was then diluted with saline to give the appropriate concentration for dosing. The so lutions were made up within one hour prior to the dosing of the hamsters. All dosing was completed in less than 3 hr. The DMH was analyzed after each dosing. During the test period, room temperature was maintained at 22 2C and the relative humid ity ranged from 40% to 80%. Tb minimim contam ination of room air with asbestos, each cage was totally enclosed. Incoming air was filtered to the cages through glass fiber filters while exit air was filtered through a fiberglass roughing filter fol lowed by a bag housing filter. The cage atmo sphere was negative relative to the room and the room was maintained at a slightly negative atmo sphere in relation to corridor air. Air flow within the animal rooms was maintained with a mini mum of 20 air changes/hr. Flourescent lighting was provided 12 hr/day. Clinical Examinations and Pathology All hamsters were observed daily for signs of toxicity. Body weights ofindividual animals were recorded weekly for the duration of the study. All animals were allowed to die or were killed with pentobarbital sodium when moribund. A com plete postmortem examination was performed on all animals not severely cannibalized or autolyzed. Thus, the number of animals from which particular organs or tissues were examined mi- Group SB chrysotile control Dl chrysotile control DMH and 1R chrysotile control Amodte control SR chrysotile Dt chrysotile DMH DMH and IB chrysotile Antoni te Ihble S Disposition of hamster* in oral asbestos study. Histopathologic Sex On teat evaluation Mining Cannibalized M 126 116 0 3 F 126 114 0 1 M 126 116 0 0 F 126 119 0 0 M 126 119 0 0 F 128 120 1 0 M 127 122 0 0 F 126 119 1 0 M 253 233 0 1 F 252 228 1 0 M 261 246 0 0 F 262 244 1 0 M 127 127 0 0 F 126 122 0 0 M 176 173 0 0 F 174 161 3 0 M 262 248 0 0 F 264 237 5 0 Autolyzed 6 6 8 4 3 2 4 1 10 17 3 3 0 1 2 6 3 5 Miaaexed 2 5 2 3 3 C< 6-- 61 Sr- 9 <= 6M so 4 i# 0~ 3 1^ 4 1 7 EFFECTS IN HAMSTERS OF DIETARY EXPOSURE TO ASBESTOS 15 STQ096953 croecopically varies and does not necessarily rep resent the number of animals that were placed on study in each group (Tkble 6). Since the gastrointestinal tract was chosen as one of the target organs prior to the study, it was handled in a manner slightly different from the usual in standard rodent lifetime bioassays. Prior to placement in fixative, the entire esophagus was opened and pinned with the exterior surface adja cent to cardboard. The stomach and cecum were prepared similarly. Lengths of duodenum and il eum (2 cm) and two portions of jejunum were placed unopened in fixative. The remaining small intestine was opened and gently washed with saline and it was then carefixlly examined. Sus pect lesions were processed separately and identi fied individually as to location. Likewise, the en tire colon with anus was opened, examined, and pinned to cardboard prior to fixation. The size and location of masses were recorded. Masses greater than 1 mm in diameter were removed as separate specimens for processing. After fixation and prior to embedding, the colon was "carpet-rolled'' start ing at the posterior end, with the mucosal surface inward. All tissues were fixed in 10% neutral buffered formalin, sectioned, and stained with hematoxy lin and eosin. Tissuea/organs examined micro scopically were: tissue masses, the above men tioned portions of gastrointestinal tract, mesenteric and bronchial lymph nodes, mam mary gland, salivary gland, thigh muscle, bone marrow (sternum), nasal cavity with turbinates, larynx, trachea, lungs, and bronchi, heart, thy roid, parathyroid, liver, gallbladder, pancreas, spleen, kidneys, adrenal glands, urinary bladder, seminal vesieles/prostate/testes, ovaries/uterus, brain, pituitary gland, eyes and spinal cord. Se lected sections were stained with Bennhold's Congo red to demonstrate amyloid. Data Recording and Statistical Methods The individual animal pathology data on this experiment were recorded in the Carcinogenesis Bioassay Data System. The data elements include descriptive information on the chemicals, ani mals, experimental design, clinical observations, survival, and individual pathologic results. Probabilities of survival were estimated by the product-limit procedure of Kaplan and Meier (3). Animal* were statistically censored as of the time that they died of other than natural causes or were found to be missing; animals dying from natural causes were not statistically censored. Differences in survival were evaluated by Cox's life table method (41 The incidence of neoplastic or nonneoplastic lesions has been given as the ratio of the number of animals bearing such lesions at a specific ana tomic site (numerator) to the number of animals in which that site was examined (denominator). In most instances, the denominators included only those animals for which that site was exam ined histologically. However, when macroscopic examination was required to detect lesions (e.g., skin or mammary tumors) prior to histologic sam pling, or when lesions could have appeared at multiple sites (e.g., lymphomas), the denomina tors consist of the numbers of animals necropsied. For the statistical analysis of tumor incidence data, two different methods of adjusting for intercurrent mortality were employed. Each used the classical methods for combining contingency ta bles developed by Mute] and Haenszel (5). The first method of analysis assumed that all tumors of a given type were fatal, i.e., they either directly or indirectly caused the death of the animal. According to this approach, the propor tions oftumor-bearing animals in the treated and control groups were compared at each point in time at which an animal died with a tumor of interest The denominators of these proportions were the total number of animals at risk in each group. These results were then combined by the Mantel-Haenszel methods to obtain an overall probability (p) value. This method of adjusting for intercurrent mortality is Cox's life table method ). The second method of analysis assumed that all tumors of a given type were "incidental,' i.e., they were merely observed at autopsy in animals dy ing of an unrelated cause. According to this ap proach, the proportions of animals found to have tumors in treated and control groups were com pared in each of five time intervals. For male hamsters these time intervals were 0-52 weeks, 53-78 weeks, 79-92 weeks, 93-103 weeks and beyond 103 weeks. For female hamsters whose median survival was considerably less than that of the males, the time intervals were 0--44 weeks, 45-52 weeks, 53-60 weeks, 61-68 weeks and be yond 68 weeks. The denominators ofthese propor tions were the number of animals actually autopsied during the time interval. The individual time interval comparisons were then combined by the previously described methods to obtain a single overall result (6). In addition to these tests, one other Bet of statis tical analyses were carried for each primary tu mor the Fisher exact test based on the overall 16 McConnell etal. proportion of tumor-bearing animal(7). All re ported p value* are one-sided Except where noted, the three alternative analyses gave simi lar results. Results Establishment of Tfest Groups The experiment was designed to evaluate the effects of orally ingested amosite or chrysotile asbestos during the entire life of the animal, starting from the time it was able to eat solid food. For this reason, the mated female hamsters had been on the test diets for approximately 2 weeks when the first litters were born. Of the females, 10-15% were not pregnant, aborted, or their litters died immediately after birth. Several more dams died after showing a prolapsed rectum in the week following birth. The incidences of infertility and neonatal deaths were unrelated to the test diet. 7b minimise the chance that the mothers would reject or cannibalize their young, the litters were not handled during lactation. Many of the pups which died during the nursing period were cannibalized by their mothers. In those pups in which a postmortem examination was possible, the stomachs were typically without food (milk), suggesting maternal rejection or in ability to compete with litter mates. None ofthese observations were compound-related. Approximately 2% of the offspring in all groups died between weaning and 14 weeks ofage due to cage fighting or an enteritis of undetermined origin. Histologically, the disease was compatible with the acute form of proliferate ileitis (Vet tail"), a common disease of hamsters. Combina tions of cage fighting and enteritis were also observed. These deaths were not compoundrelated, although cage fighting was more severe in the SR chrysotile and its temporal control group than in the other two portions of the study. Replacement hamsters were incorporated into the groups (in additional cages) to maintain group sizes until the animals were 12 weeks ofage; from this time on, no additional hamsters were added to the experimental groups. The extra hamsters were killed. Body Weights and Clinical Signs Body weight gain was not adversely affected in any dose group, including the group given 1,2dimethylhydrazine dihydrochloride (DMH). In fact, both types of asbestos appeared to increase body weight in most of the dosed groups. No compound-related clinical signs were ob served during the entire study. Occasional skin lesions and bite wounds were observed in both sexes, but were more apparent in males; these became less of a problem after the hamsters were 20 weeks of age. Survival Survival was not adversely affected by any of the test diets with the possible exception ofDMHtreated female hamsters. Survival rates were ac tually higher in the amosite and SR and IR chrys otile groups relative to the temporal controls. The median life-span of females (control and treated) was shorter than that of corresponding groups of males (Thble 7). The median survival of control ST0096954 Tkble 7. Median life epan of hamatere in oral asbeetoe study. Group Sex Median life span, weeks IR chryaotile control Dt chryaotile SR chryaotile control SRchryeotile DMH and IR cbryiotile control DMH IR chryaotile and DMH Amoaita control Amoaite M F M F M F M F M F M F M F M F M F S3 61 86 59 77 57 87 63* 82 57 82 64k 90 63* 81 55 84 60 Significantly ip < 0.06) improved overall survival relative to control! (life table analyeia). ^Significantly ip < 0.06) reduced overall aurvival relative to control! (life table aaalyai!). EFFECTS IN HAMSTERS OF DIETARY EXPOSURE TO ASBESTOS 17 female group* was 55-61 weeks, compared to 7783 weeks for control male hamsters Clhble 7). Pathology The number of hamsters available for histo pathologic examination is shown in Thble 6. Most animals not examined pathologically were ex cluded because of autolysis or cannibalization. Review of the clinical records of hamsters lost to autolysis or cannibalization gave no indication that these animals had neoplasia. A variety of neoplasms was observed in control (Thbles 8 and 9) and asbestos-exposed hamsters (Tkbles 10-17). The proportion of control male or female hamsters bearing primary tumors was not statistically different among the four control groups. Thus, statistical comparisons were made with pooled controls as well as with temporal controls. Overall, the male hamsters had a slightly higher rate ofneoplasia than the females. Those organs with greater than 4% incidence of neoplasia in dosed or control groups were the adrenal gland, pancreas (islets of Langerhans), parathyroid, and reticuloendothelial system. The only organ showing an increased rate of neoplasia in chrysotile-exposed hamsters com pared to the controls was the adrenal cortex. In male hamsters, the incidence of cortical adeno mas was significantly increased ip < 0.01) in the SR and IR chryaotile groups compared with the pooled controls but not in the DMH chryaotile or amosite groups. None of the chryaotile groups showed a significant (p < 0.05) increase in corti cal adenomas relative to their temporal control groups. A similar increase in cortical adenomas was observed in the female IR chryaotile group compared with pooled controls, but this also ceased to be significant when compared with the temporal control group. In only three other instances did specific tumor types show significant effects relative to pooled or temporal controls. The only statistically signifi cant {p < 0.05) difference in tumor incidence observed in the amosite study was a decrease in islet-cell adenomas observed in female hamsters. Female hamsters administered SR chrysotile showed a significantly ip < 0.05) decreased inci dence of islet-cell adenoma relative to pooled con trols flhble 16). Male hamsters administered DMH showed a significantly ip < 0.05) increased incidence of leukemia or malignant lymphoma relative to pooled controls (Thble 16). The only group to show a significant ip < 0.05) increase in overall primary tumors was the male IR chrysotile group. This increase was due pri marily to adrenal tumors. Male hamsters receiv ing SR chrysotile or DMH and IR chrysotile also ST0096955 table 8. Incidence of primary tumor* in nude hamster control group*. Animals with primary tumors Skin or subcutaneous tissue, all tumors Lung or trachea, all tumors Adrenal Cortical adenoma Cortical carcinoma Pheochromocytoma Other tumors Pancreas Islet-cell adenoma Islet-cell carcinoma Thyroid C-cell adenoma C-ccll carcinoma Other tumors Parathyroid, adenoma CJ. tract, all turnon Pituitary, all tumor* Kidney, all tumors Liver, all turnon Leukemia or malignant lymphoma Hemangioma or hemangioaarcoma All other tumors Short-range chrysotile control 21-T 15(1891 0/115(0*1 0/115(0*1 7/115 (6*) 3/115 (3*1 2/115 (2*1 0/115 (0*1 2/111 (2*1 1/111 (1*) 3/109 (3*1 1/109(1*1 On09 (0*) 0/72 (0*) 2/115 (2*) 0/84 (0*1 0/115 (0*) 0/115 (0*) 2/115(2*1 0/115 (0*1 1/115(1*1 Intermediaterange chrysotile control 26/116/22*1 1/116(1*1 0/116(0*) 7a 15 (6*1 3/115(3*1 5/115(4*1 3/115(3*1 7/110(6*1 0/110(0*1 3/106 (3*1 1/106(1*1 0/106 (0*1 1/71 (1*) 1/116(1*1 0/77 (0*1 2/116(2*1 0a 16 (0*1 1/116(1*1 0/116(0*1 on 16 (0*i DMH and intermediate- range chrysotile control 27/119 (23*1 1/119(1*1 9/119(0*1 3/117 (3*1 4/117(3*1 3/117 (3*i 2/117(2*1 8/110 (7*1 0/110(0*1 0/107 (0* 1 0/107(0*1 1/107(1*1 1/64 (2*1 2/119(2*1 0/80 (0*' 1/119 (l*i 0/119 (0*1 4/119(3*1 3/119 (3*1 3/119(3*1 Amoeite control 21/122 <17*) 0/122 (0* > on20 (0* i 8/119 (7* i 3/119(3*' 3/119(3*i l/119il*i 3/114(3*i 0/114 (0*i l/106(l*i in06u*i 0/106 (0* > 0/64 (09' 1/112(1*1 0/81 (0*1 ia20(l*l 0/120 (0*1 1/122(1*1 2/122(2*1 1/122(1*1 18 McConnell et al. bowed an elevated incidence of primary tumors relative to pooled controls. However, when sur vival differences were taken into account by a life table analysis, these differences were not statisti cally significant. Female chrysotile groups showed little evidence ofan increased incidence of primary tumors relative to temporal or pooled controls. Ikbie 8. Incidence of primary tumors in female hamster control groups. Animals with primary tumors Sun or subeutimeou* tissue, all tumors Lung or trachea, all turnon Adrtoftl fiorticsl AfUnnma Cortical carcinoma Pheochromocytoma Other turnon Pancreas Islet-csll adenoma Islet-cell carcinoma Thyroid C-oell adenoma C-cell carcinoma Other turnon Parathyroid, adenoma GJ. tract, all turnon Pituitary, all tumors Kidney, all turnon Liver, all turnon Leukemia or malignant lymphoma Hemangioma or hemangiotarcoma Uterus, all turnon All other turnon Short-range chrysotile control 19/114 (17%) 0/114 (0%) 0/114 (0%) 4/112 (4%) 0/112(0%) 0/112 (0%) 0/112 (0%) 2/109 (2%) 1/109 (1%) 2/106 (2%) 1/107 (0%) 2/107 (2%) 3/68 (4%) 1/114 (1%) 077(0%) 0/114 (0%) 0114 (0%) 2/114 (2%) 0,114(0%) 3/113 (3%) 3114 (3%) Intermediaterange chrysotile control 17/119(14%i 1/119(0%! 0/119 (0%i 6/118 (5%) 0/118(0%) 0/118(0%) 0118 (0%) 6/116 (4%) 0/116 (0%) 3/116 (3%l 1116(0%) 0/116(0%) 1/77(1%) 2/119 (2%) 2/67 (3%) 1119(1%) 0/119 (0%) 1119 (09) 0119(091 1119(19) 0/119 (0%) DMH and intermediate- range chrysotile control 15/120(129) 1/120 (09) 0119 (09) 3/120 (2%) 0/120 (09) 0/120 (0%) 0120(0%) 6116(4%) 0116 (0%) 0112(09) 0/112(1%) 1112 (0%) 1/74 (1%) 1120(191 0/62 (0%) 0120 (09) 0/119(09) 3120(291 1/120(19) 2/120 (29) 1120(191 Amoaite control 15119(139) 0/119(09) 0119(09) 2/118(29) 0118 (09) 0118(091 0118 (09 i 3115(39) 0/115 (09) 1/106(19) 1106(09) 0106(09) 1/61 (19) 1119(19i 079 i09> 0119(09) 0118(09) 2119(29) 1119(19) 2119(291 2119(29) ST009695 Table 10. Incidence of primary tumors in male hamsters administered amoaite asbestos. Animals with primary tumors Skin or subcutaneous tissues. all tumors Lung and trachea, all turnon Adrenal Cortical adenoma Cortical carcinoma Pbeochromocytoms Other tumors Pancreas Islet-call adenoma Islet-cell carcinoma Thyroid C-ctll adenoma C-cell earnnoma Other turnon Parathyroid, adomons GX tract, all turnon Pituitary, all turnon Kidney, all turnon Liver, all tumors Leukemia or malignant lymphoma H--Mnptmi Trrhsiiiengiii--rriane All other turnon Pooled codtroll 96/472 (20%) 2/472 1%) 0/470 (0%) 25/466 (5%) 13/466 (3%) 13/466 (3%) 6/466 (1%) 30/466 (4%) 1/446 1%) 7/428 (2%) 1/428 1%) 1/428 1%) 2/271 (1%) 6/472 (1%) 0/322 (0%) - 4/470(1%) 0/470 (0%) 8/472 (2%) 6/472 (1%) 6/472 (1%) Amoaite controls 21/122 (17%) 0/122 (0%) 0/120 (0%) 8/119(7%) 3/119(3%) 3/119(3%) 1/119(1%) 3/114(3%) 0/114 (0%) 1/106(1%) 0/106 (0%) 0/106 (0%) 0/64 (0%) 1/122(1%) 0/81 (0%) 1/120(1%) 0/120 (0%) 1/122(1%) 2/122 (2%) 1/122(1%) Amositetreated 7/248 (2391 0/248 (09) 0/248(09) 13/246 (59) 7/246(39) 4/246 (29) 2/246 (19) 11/234(59) 0/234 (09) 7/221 (39) 2/221 (19) 2/221 (19) 2/150 (19) 6/248 (29) 0/182(09) 2/248(19i 0/247 (09) 6/248 (291 2/248 (19) 2/248 (19) EFFECTS IN HAMSTERS OF DIETAR Y EXPOSURE TO ASBESTOS Able II. Incidence of primary tumor* in female hamster* administered amosite asbestos Pooled control* Amoeite controls Animals with primary tumor* Skin or subcutaneous tissues. all tumors Lung and trachea, all tumors Adrenal Cortical adenoma Cortical cardnoma Fheochromocytoma Other tumor* Pancreas Islet-cell adenoma Islet-cell carcinoma Thyroid C-cell adenoma C-cell carcinoma Other tumor* Parathyroid, ademona GJ. tract, all tumor* Pituitary, all tumor* Kidney, all tumor* Livar, all tumor* Leukemia or malignant lymphoma Hemangioma or hemangiosarcoma Uterus, all tumor* All other tumor* 66/472(14%) 0/472 (0%) 0/471 (0%) 15/466 (3%) 0/466(0%) 0/468(0%) 0/468(0%) 15/456 (3% 1 0/222(0%i 6/440 (1%) 1/440 1%) 2/440(1%) 6/280 (2%) 5/472 (1%) 2/285 (1%) 1/472 1%) 0/472 (0%) 7/472 (1%) 2/472 1%) 8/471 (2%) 6/472 (1%) 15/119(13%) 0/119 (0%) 0/119 (0%) 2/118 (2%) 0/118 (0%) 0/118 (0%) 0/118(0%) 3/115 (3%) 0/115(0%) 1/106(1%) 0/106(0%) 0/106(0%: 1/61 (1%I 1/119(1%) 079 (0%) 1/119 <0%l 0/118 (0%) 2/119 (2%i 1/119(1%' 2/119(1%) 1/119(1%! *p < 0.05 decrease relative to pooled controls (life table and incidental tests). Amoeitetreated 30/237(13%) 2/237 (1%) 0/234 (0%) 6/234(3%) 0/234(0%) 2/234 (1%) 0/234(0%) 2/222 (1%)* 1/456 (1%) 4/215 (2% l 1/215 1%) 0/215 (0%) 1/141 (1%) 4/237 (2%) 0/149 (0%) 0/236(0%) 0/234 (0%) 3/2236 (1%) 3/237(1%) 1/236(<1%) 2/237 (1%) 19 ST009695 7 Ihble 12. Incidence of primary tumor* in male hamster* administered short-range chrysotile asbestos. Pooled controls Short-range chrysotile controls Short-range chrysotile Animals with primary tumors Skin or subcutaneous tissue, all tumors Lung or trachea, all tumor* Adrenal Cortical adenoma Cortical carcinoma Pbaochromocytoma Other tumor* Pancreas Islet-cell adenoma Islet-cell carcinoma Thyroid C-cell adenoma C-cell carcinoma Other tumors Parathyroid, adenoma GJ. tract, all tumor* Pituitary, all tumor* Kidney, all tumor* Liver, all tumor* Leukemia or malignant lymphoma Hemangioma or hemangiosarcoma All other tumors 95/472 (20%) 2/472 1%) 0/470 (0%) 25/466 (5%) 13/466 (3%) 13/466 (3%) 6/466 (1%) 20/445 (4%) 1/445 1%) 7/428 (2%) 3/428 (1%) 1/428 1%) 2/271 (1%) 6/472(1%) 0/322 (0%) 4/470 (1%) 0/470 (0%) 8/472 (2%) 6/472(1%) 6/472(1%) 21/116(18%) 0/115 (0%) 0/115 (0%) 7/116 (6%) 3/115 (3%) 2/115 (2%) 0/115 (0%) 2/111 (2%) mil a%) 3/109 (3%) 1/109 (1%) 0/109 (0%) 072(0%) 2/115 (2%) 0/84 (0%) 0/115 (0%) 0/115 (0%) 2/115 (2%) 0/115 (0%) 1/115(1%) 64/233 (27% > 0/233(0%) 0/231 (0%) 26/229 (11%H> 8/229(3%) 4/229 (2%) 1/229 1%) 15/218 (7%) 0/218 (0%) 3/207 (1%) 1/207x1%) 0/207 (0%) 3/132 (2%) 0/233 (0%) 0/159 (0%) 3/232(1%) 0/232 (0%) 3/233 (1%) 4/233 (2%) 3/233 (1%) *p < 0.05 vs. pooled controls. tip m 0.152 (life table); p 0.065 (inadental tumor test) and p " 0.019 (Fisher's exact test) v*. pooled controls. 10 McConnell et al. Table 13. laddeaet ot primary tumor* in female hamster* administered short-range chryaotile asbestos. Pooled controls Short-range chryaotile controls Animal* with primary tumor* Skin or subcutaneous tissue, all tumor* Lung or trachea, all tumors Adrenal Cortical adenoma Cortical carcinoma Fbeochromocytoma Other tumors Pancreas Islet-cell adenoma Ulet-cell carcinoma Thyroid C-cell adenoma C-cell carcinoma Other turnon Parathyroid, adenoma Gl. tract, all tumors Pituitary, all turnon Kidney, sill turnon Liver, all turnon Leukemia or malignant lymp^m* Hemangioma or bemangioasjcoma Uterus, all turnon All other turnon 66/472 (14%) 0/472 (0%) 0/471 (0%) 15/466 (3%) 0/468(0%) 0/468(0%) 0/468(0%) 15/456(3%) 1/456 Kl%> 6/440(1%) 1/440 1%! 2/440 1%) 6/280 (2%) 5/472(1%) 2/285(1%) 1/472 1%) 0/472(0%) 7/472(1%) 2/472X1%) 8/471 (2%) 6/472(1%) 19/114(17%) 0/114 (0%) 0/114(0%) 4/112 (4%) 0/112 (0%) 0/112 (0%) 0/112 (0%) 2/109 (2%) 1/109(1%) 2/107 (2%l 1/107 (0%) 2/107(2%) 3/68 (4%) 1/114(1%) 0/77 (0%) 0/114(0%) 0/114 (0%) 2/114(2%) 0/114(0%) 3/113(3%) 3/114(3%) p < 0.05 docreaae relative to pooled controls (life table and incidental tumor test). Short-range chrysotile 28/228(12%) 3/228 (1% i 0/228(0%' 8/226(4%) 0/226(0%) 3/226(1%) 1/226x1%) 2/21" il%> 0,217 i0%) 0.214 (0%) 0214(0%) 0,214 (0%) 3139 (2%) 1/228x1%' 0/132 )]%) 0/228(0%) 0,228 (0%' 2228 (1% i 1/228x1%' 5 226 (2%) 3228 tl%' tA H o o V0 to cn 00 Thble 14. Incidence of primary turnon In male hamaten administered intermediate-range chrysotile asbestos. Pooled controls Animals with primary tumon Skin or subcutaneous tissue, ell tumon Lung or trachea, all tumon Adrenal Cortical adenoma Cortical carcinoma Phoochromocytoma Other tumon Pancreas Islet-cell adenoma Islet-cell carcinoma Thyroid C-cell adenoma C-cell carcinoma Other tumon Parathyroid, adenoma G.l. tract, all tumon Pituitary, all tumon Kidney, all tumors Liver, all tumon Leukemia or malignant lymphoma Hemangioma or hemangioaarcoma All other tumon 95/472 (20%) 2/472 1%) 0/470 (0%) 25/466 (5%) 13/466(3%) 13/466(3%) 6/466(1%) 20/445(4%) 1/445 (<1%) 7/428 (2%) 3/428(1%) 1/428 (<1%) 2/271 (1%) 6/472 (1%) 0/322 (0%) 4/470 (1%) 0/470 (0%) 8/472 (2%) 5/472 (1%) 5/472 (1%) p < 0.01 **. pooled control*. *p < 0.06 t. intermediate-ranc* chrysotile control*. *p < 0.05 v*. pooled control*. Intermediaterange chrysotile controls 26/116(22%) 1/116(1%) 0/116(0%) 7/115(6%) 3/115(3%) 5/115(4%) 3/115(3%) 7/110(6%) 0/110(0%) 3/106(3%) 1/106(1%) 0/106(0%) 1-71 (1%) 1/116(1%) 077 (0%) 2/116(2%) 0/116 (0%) 1/116(1%) 0/116(0%) 0/116(0%) Iniermediatennge chrysotile 78.245 (32% u* 0245 (0%' 1,244 1% i 24244 <10% * 7/244 ( 3%) 11244(5%' 1244X1%) 15226)7%) 1226X1%' 5216(2%' 4216 (2% ) 1216X1%) 4/138 (3%' 3245)1%' 0182 )0%) 1.245x1%) 0244(0%) 1024514%) 1.242X1%) 2245 (1%) EFFECTS IN HAMSTERS OF DIETARY EXPOSURE TO ASBESTOS 21 Ihble IS. Incidence of primary turnon In female hamster* administered intermediate-rams chrysotile asbestos. Animals with primary tumors Skin or subcutaneous tissue, all turnon Lung or trachea, all tumor* Adrenal Cortical adanntni Cortical carcinoma Pbeoehramocytema Other tumor* Pancreas Islet-cell adenoma Islet-cell cardnoma Thyroid C-cell adenoma C-cell cardnoma Other tumor* Parathyroid, adenoma Gi. tract, all tumors Pituitary, all tumors Kidney, all tumor* Liver, all tumor* Leukemia or malignant lymphoma Hemangioma or hemangicsarcoma Uterus, all turnon All other turnon p < 0.05 vt. pooled controls Pooled controls 66/472 (14%) 0/472(0%! 0/471 (0%) 15/468 (3%) 0/468(0%) 0/468(0%) 0/468 (0%) 15/456 (3%) 1/456 1%) 6/440(1%) 1/440 1%> 2/440 1%> 6/280 (2%) 6/472(1%) 2/285(1%! 1/472 1%> 0/472 (0%) 7/472(1%) 2/472 1%) 8/471 (2%) 6/472(1%) intermediaterange chrysotile controls 17/119(14%) 0/119(0%! 0/119 (0%) 6/118 (5%) 0/118(0%) 0/118(0%) on 18 <0%! 5/116 (6%i 0/116(0%! 3/115<3%i 0/115(0%) 0/115(0%) 1/77(1%) 2/119 (2%i 2/67 (3%) 1/119(1%) 0/119 (0% i 0/119(0%) 0/119 (0%) 1/119(1%) 0/119 (0%) Intermediaterange chrysotile 39/244 (16% i 2/244(1%! 0/243 (0%) 18/234 (8% 1/234 l%i 1/234 1%' 0/234(0%) 4/236 (2%) 0/236(0%' 2/223(l%i 0/223(0%) 1/223 1%) 1/148(1%) 1/244 1%) 2/164 (1%) 0/243(0%) 0/234 (0%) 2/244 (1%) 1/244 1%) 7/240(3%) 2/244(1%) ST0096959 Thbie 16. Incidence of primary tumor* in male hamsters administered 1,2-dimetbythydrazine dibydrochloride (DMH) or intermediate-range chrysotile asbestos and DMH. Pooled controls DMH and intermediaterange chryeotile controls DMH DMH and intermediate- range chrysotile Animals with primary turnon Skin or subcutaneous tissue, all turnon Lung or trachea, all turnon Adrenal Cortical adenoma Cortical earanoma Pheoehromocytoma Other turnon Panose* lalet-cell Islet-cell carrinotna Thyroid C-cell adenoma C-cell carcinoma Other tumors Parathyroid, Gi. tract, all tumors Pituitary, all tumors Kidnsy, all tumors Livar, all tumors Ijukbmti milipiftt lytwpkAm* All othar tumors 95/472 (20%) 2/472 1%> 0/470 (0%) 25/466 (5%) 13/466 (3%) 13/466(3%) 6/466 (1%) 20/445 (4%) 1/445 1%) 7/428 (2%) 3/428 (1%) 1/428 1%) 2/271 (1%) 6/472 (1%) 0/322 (0%) 4/470 (1%) 0/470 (0%) 8/472 (2%) 5/472 (1%) 5/472(1%) 27/119 (23%) 1/119 (1%) 0/119(0%) S/117 (3%) 4/117 (4%) 3/117 (3%) 2/117 (2%) 8/110 (7%) 0/110 (0%) 0/107 (0%) 0/107 (0%) 1/107 (1%) 1/64 (2%) 2/119 (2%) 0/80(0%) 1/119(1%) 0/119 (0%) 4/119 (4%) 3/119 (3%) 8/119 (3%) 29/127 (23%) 0/127 (0%) 0/126(0%) 3/127 (2%) 2/127 (2%) 4/127 (3%) 0/127 (0%) 6/114 (5%) 0/114 (0%) 2/118(2%) 0/118 (0%) 0/118 (0%) 081 (0%) 3/127 (2%) 0/87 (1%) 0/127 (0%) 2/127 (2%) 7/127 (6%)b 2/127 (2%) 1/127 (1%) 61/173 (29%)* 1/173(1%) 0/173 (0%) 8/171 (5%) 7G71 (4%) 6/171 (4%) 1/171 <1%I 10/167 (6%) 1/167 (1%) 3a63 (2%) ia63 (1%) 0/163 (0%) 2ai8(2%i 4/173(2%) 2/123 (2%) 0/173 (0%) ia73 (1%) 8a73 (5%) 2a73 (1%) 4/173 (2%) *P " 0.257 (life table); p - 0.038 (incidental tumor test); p m 0.009 (Fisher's suet test) vt. pooled controls, tp < 0.05 vs. pooled controls. 22 McConnell et al. Ikhii 17. Incidence of primary tumors in (null hamster* artmlnlstei sil l^-diaMthythydraslne dihydrochloride (DMH) or hterMdiii*-ru|t chryaodla asbaates and DMH. Animals with primary tamer* Skin or subcutaneous tissue, all tumors Lung or traebaa, all tumors Adrenal Cortical adenoma Cortical earnnoma Phaochromoeytoma Other tumon Pancreas Islot-eall adenoma Islet-cel) raronomi Thyroid C-esll adenoma C-cell carcinoma Othar tumors Parathyroid, adenoma Gl. tract, all tumors Pituitary, all tumors Kidney, all tumors Liv*r, all tumors Leukemia or malignant lymphoma Hemewpnypy gy Uterus, all tumor* All other tumors Pooled controls 6/472 (14%) 0/472(0%) 0/471 (0%) 15/468(3%) 0/468(0%) 0/468(0%) 0/468(0%) 15/456 (3%) 1/456 1%) 6/440 (1%) 1/440 1%) 2/440 1%) 6/280 (2%) 5/472 (1%) 2/285 (1%) 1/472 1%) 0/472 (0%) 7/472 (1%) 2/472 1%) 8/471 (2%) 6/472 (1%) DMH and miff Tttlti itt- n&ft chrysotile controls 15/120 (12%) 0/120 (0%) 0/119 (0%) 3/120 (2%) 0/120 (0%) 0/120(0%) 0/120(0%) 5/116 (4%) (me (0%) on 12(0%) 1/112 (1%) 1/112 (0%) 1/74 (1%) 1/120(1%) 0/62 (0%) 0020(0%) 0019 (0%) 3020(2%) 1020(1%) 2020(2%) 1020(1%) DMH 15022 (12%) 1022(1%) 0022(0%) 2020 (2%) 0/120(0%) 0020(0%) 0020 (0%) 2019 (2%) 0019 (0%) 0008 (0%) 0006(0%) 0/108 (0%) 2/57 (4%) 2022(2%) 0/59(0%) 0/122 (0%) 0021 (0%) 2022 (2%) 0022(0%) 2016(2%) 2022 (2%) DMH and iatermadiata- rangs chrysotile 19061 (12%) 0/161 (0%) 1/160(1%) 6058 (4%> 2/158 (1%) 0058(0%) 0058 (0%) 4/149 <3%i 1/149 (0%) 0/141 (0%) 0041(0%) 0/141 (0%) 0/91 (0%) 0061 (0%) 0/109 (0%) 0061 (0%) 0061 (0%) 3061 (2%) 1/161(1%) 2/156(1%) 2/161 (1%) to --i Ca/ VO Ot I o Thbie 18- laddoM of (iHnislMtiul tract tumor* in hamster* administered amoaite asbestos. Stomach (number examined) Squamous call papilloma Papilloma Small intestine (number examined) Adenoma Adenocarcinoma Large intestine (number examined) Adenoma Papillary adenoma Adenocarcinoma lipoma Rectum (number examined) Adenoma Adenomatous polyp Fibroma Squamous oell papilloma Pooled controls MF (464) 3 0 (467) 1 1 (464) 0 0 0 0 (472) 1 0 0 0 (468) 0 0 (469) 0 0 (468) 1 0 1 1 (2721 1 0 1 0 Amosite controls MF (120) 1 0 (120) 0 0 (118) 0 0 0 0 (122) 0 0 0 0 (117) 0 0 (117) 0 0 (116) 0 0 0 0 (119) 1 0 0 0 Amositetreated MF (247) 4 0 (246) 0 0 (246) 0 1 0 0 (248) 0 1 0 0 (236i 0 3 (236) 0 0 (235) 0 0 0 0 (237) 0 0 0 0 Males and females administered DMH did not show a significant (p < 0.05) increase in intesti nal neoplasia. Nor did the intermediate-range chrysotile produce a higher rate of intestinal neo plasia in DMH-dosed animals. A summary of all gastrointestinal tumors observed in this study iB given in Ifcbles 18 and 19. None of the treated groups showed an increased rate of neoplasia in the gastrointestinal tract which was the proposed target organ. While this study was not designed to evaluate nonneoplastic disease, noteworthy lesions were observed. None appeared to be dosage related; rather, they were consistent with lesions that are normally found in aging hamsters. It was the pathologists' opinion that the most important le- EFFECTS IN HAMSTERS OF DIETARY EXPOSURE TO ASBESTOS Ikblt II. IcMci of gastrointestinal tract tutors la hamsters tdatniitend ehryeotile fltnmarh (number examined) Squamous call papilloma Carcinoma in titu Papillary adenoma Small intaatin* (number examined) Adenoma AAooBKiardocifiit Lars* intaatin* (number examined) PeplUma Adenoma Papillary aiUimma A t^ftwawTtiwna Lipoma Adenomatout polyp Rectum (number examined) Adenoma Papillary adenoma Fibroaamma Squamous cell carcinoma Fibroma Pooled control* MF (464) 3 0 0 (467) 1 1 (464) 0 0 0 0 0 0 (472) 1 0 0 0 0 (468) 0 0 0 (469) 0 0 (468) 0 1 0 1 1 0 (472) 1 0 0 0 1 Short-range chryaotile MF (222) 0 0 0 (226) 0 0 (222) 0 0 0 0 0 0 (233) 0 0 0 0 0 (224) 0 0 0 (227) 0 0 (226) 0 0 0 1 0 0 (228) 0 0 0 0 0 Intermediaterange chryaotile MF (244) 1 1 1 (244) 0 0 (241) 0 0 0 0 0 0 (245) 0 0 0 0 0 (242) 0 0 1 (244) 0 0 (243) 0 0 0 0 0 0 (244) 0 0 0 0 0 DMH MF (127) 0 0 0 (127) 0 0 (126) 0 1 1 0 0 0 (127) 0 0 1 0 0 (118) 0 0 0 (120) 0 0 (118) 0 0 0 0 0 1 (122) 0 0 0 1 0 23 DMH and Intermediate, range chryaotile MF (170) 2 0 0 (170) 0 0 (1701 1 0 0 0 0 0 (173) 0 1 0 0 0 (160) 0 0 0 (159) 0 0 (159) 0 0 0 0 0 0 (161) 0 0 0 0 0 19696001S ion, responsible for many deaths, was general ized amyloidosis. The kidneys were particularly affected by diffuse accumulation of amyloid, which replaced glomeruli and infiltrated tubular interstitium to a point where the normal cortical architecture was obliterated. Other organs which showed significant accumulations of amyloid were adrenal gland, liver, spleen and the epithe lium of the small intestine. Amyloid within the walls of blood vessels was observed in many tis sues. Many of the livers were cirrhotic, infiltrated with amyloid, and contained large cystic struc tures filled with a lightly staining proteinaceous fluid. These structures were interpreted as cystic bile ducts and are consistent with what others have termed "retention cysts." At times, these cysts were so large and/or numerous that less than half of the liven remained. Other nonneoplastic lesions that were observed in more than 59b of the hamsters in any of the experimental groups are as follows: (1) skin, chronic dermitis; (2) lung, interstitial pneumoni tis; (3) spleen, lymphoid atrophy; (4) lymph node, hyperplasia; (5) heart, atrial thrombosis; (6) gall bladder, edema and calculi; (7) stomach (nonglandular), hyperkeratosis or acanthosis; (8) colon, intussusception, inflammation; (9) urinary blad der, chronic inflammation, hyperplasia; (10) adre nal gland, cortical and medullary hyperplasia; (11) thyroid gland, follicular atrophy; (12) pitui tary gland, degeneration; (13) ovary, atrophy; (14) uterus, inflammation, endometrial hyperpla sia; (15) vagina, acute inflammation, squamous metaplasia. Discussion The dinicopathologic results in this study showed that the chronic ingestion of 19k amosite (8) or chryaotile (SR and IR) (9) asbestos in the diet did not have any adverse effect on body weight gain and survival seemed to be enhanced. An explanation for these observations is not ap parent. The major organ which showed a statistically significant (p < 0.05) increased rate of neoplasia was the adrenal cortex in male and female ham sters exposed to IR chrysotile asbestos and males exposed to SR chrysotile asbestos when compared with pooled controls. However, statistical signifi cance was lost when these groups were compared to their temporal controls. It is difficult to imag ine how oral asbestos, even though it is known to be absorbed through the gastrointestinal tract (10), could cause an increased tumor rate in the adrenal cortex without causing similar increases in tumors in other abdominal organs and tissues, i.e., gastrointestinal tract and peritoneum. For these reasons, the biologic importance of adrenal tumors in this study is doubtful. The overall in crease in total primary tumors in male IR chryso- 24 UiCOXXELL ET At ST00969G2 tile hamsters can be explained primarily on the basis of an increased incidence of adrenal tumors in this group. The enhanced survival of animals in the chrysotile groups also contributed to the elevated incidence of primary tumors observed in these groups compared with controls. The only other instance of an increased rate of neoplasia was a significant (p < 0.05) increase in leukemia or malignant lymphoma in male ham sters exposed to DMH when compared to pooled controls. Again, statistical significance was lost when this group was compared to its temporal control group. This finding also loses importance because it was not observed in the DMH plus IR chrysotile group. Other such studies involving the long-term in gestion of asbestos are few. Donham et al. (11) reported equivocal results in F344 rats which were fed a diet containing 109 chrysotile for their lifetime. While they did not observe a statistically significant (p < 0.05) increase in the number of tumors in exposed animals, the authors believed that there was a trend toward increased colon lesions in general, evidence of penetration of as bestos into the colonic mucosa and possible cyto toxicity to colonic tissues and they suggested a possible relationship to peritoneal mesothelioma. Another equivocal study is that reported by Gibel et al. (121, who described an increase in malig nant tumors in the lung, kidney, liver and reticu loendothelial system, but no increase in intesti nal neoplasia in Wistar rats fed asbestos filter material (20 mg'day) for a period of 8-14 months. Cunningham et al. U3) reported two studies in male Wistar rats administered 19 chrysotile in the diet, one study of 24 months and one of 30 months. No increase in intestinal tumors was found compared to the control rats. Negative results were reported by Gross et al. (14), who fed rats a diet containing 59 chrysotile asbestos for a period of 21 months with no evidence of intestinal neoplasia. The only oral asbestos study in hamsters was reported by Smith et al. (15). They exposed groups of 30 male and female hamsters via drink ing water for lifetime to amosite asbestos, mine tailings, beach rock, and Lake Superior drinking water. They did not observe adverse effects on body weight or survival time in any of the groups. A peritoneal mesothelioma, one pulmonary carci noma, and two early squamous cell carcinomas of the nonglandular stomach were found in the hamsters exposed to amosite, but the incidence was not statistically significant (p < 0.051. Their other studies were considered negative. They con cluded that the study was essentially negative. Except for those by Donham et al. (ID and Smith et al. (151, these studies were conducted with relatively small numbers of animals. Also, some were conducted for periods of time insuffi cient for adequately testing the carcinogenic po tential of ingested asbestos. The results of the combination study (IR chrys otile plus DMH) also did not yield a significant increase in tumors above the background level observed in the DMH group alone or in the un treated control group. The DMH failed to yield a background level of intestinal tumors high enough to provide a valid test of the cocarcinogenic potential of chrysotile asbestos. For this reason, a cocarcinogenic potential of oral asbestos should be considered untested. However, the DMH plus chrysotile provides an additional IR chrysotile group for comparative purposes. It is not clear why the DMH-dosed group of hamsters failed to show an increased incidence of intestinal neoplasia. The pilot study suggested that this dose of DMH should have caused an incidence of approximately 159. DMH solutions rapidly decompose if they are at room tempera ture or if they are not properly buffered. The only long-term study designed to deter mine the cocarcinogenic potential of asbestos was reported by Ward et al. (16k They administered 1 mg amosite asbestos in saline by gavage to 6week-old F344 rats three times per week for 10 weeks. Once per week during this same period, half of the rats received subcutaneous injections of 7.4 mg kg a20xymethane iAOMi. a known in testinal carcinogen in animals. All surviving rats were killed at 94-95 weeks of age. They reported an intestinal tumor incidence of 66.79 for AOM alone, 77.19c for amosite plus AOM. and 32.69 for amosite alone. The authors concluded that while amosite did not significantly add to the incidence of AOM-induced intestinal neoplasia, amosite alone caused a relatively high rate of intestinal neoplasia. However, there was no untreated con trol group with which to compare the treated groups. These results should as well be viewed with some suspicion because the authors also reported a 149 incidence of Zymbal gland tumors in the rats exposed to amosite alone. The histori cal rate of Zymbal gland tumors in the Bioassav Program is 0.349, indicating that this is an un common spontaneous tumor. However, AOM is known to induce Zymbal gland tumors with a single dose of 5.1 mg.kg in male F344 rats produc ing a 149 incidence of tumors in this organ (17); in this study 5.1 mg kg AOM also caused a 249 incidence of intestinal neoplasia. An appropriate explanation for the high incidence of Zymbal EFFECTS f HXMSTERS OF DIETARY EXPOSURE TO ASBESTOS 25 ST0096963 gland tumors in the amoaite group would be that those animals were inadvertently exposed to AOM. If this occurred, animals would also be expected to show a high incidence of intestinal neoplasia. Conclusion Under the conditions of this bioassay, amosite asbestos and short-range chrysotile and interme diate-range chrysotile asbestos were not carcino genic when ingested by male and female Syrian golden hamsters. While there were significant increases in the rates of adrenal cortical adeno mas in male and female hamsters exposed to intermediate-range chrysotile asbestos compared with pooled control groups, these incidence rates were not significantly different when compared with the temporal control groups. Additionally, the biological importance of adrenal tumors in the absence of target organ neoplasia is question able. The cocarcinogen studies using IR chrysotile asbestos and 1,2-dimethylhydrazine dihydro chloride were considered inadequate because there was no increase in intestinal neoplasia in the DMH group. The animal phaac of this study wai parfortnad at the ITT Research Institute, Chicago, IL. Thi* project hat bees funded with federal fundi from the National Institute ofEnvironmen tal Health Science* (NIH), Department of Health and Human Services, Research Triangle Park., NC, under contract #NOlES-5-2157 Partial funding was provided by the Environmen tal Protection Agency under Interagency Agreement No. D70766. The reootrch described in this paper hat been peer and administratively reviewed by the US. Environmental Protec tion Agency and approved for presentation and publication. Mention of trade names or commercial products doe* not constitute endorsement or recommendation for use. REFERENCES 1. Proceeding* of the Joint NIEHS-EPA Conference on Biological Effects of Ingested Asbestos. Environ. Health PerspecL 9:1X3-462 (1974). 2. McConnell, E. E., Wilson, R. E., Moore, J. A., end Hetr man, J. K. Dose response of 1 j-dimethylhydrazine and methyUsoxymethanol acetate in the F344 rat. Cancer Letters 6: 271-278 (1980). 5. Kaplan, E. I*, and Meier, P. 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