Document 9JeD0Y5kg0wv991rX9BYj9MpR

BOARD OF SCIENTIFIC COUNSELORS NATIONAL TOXICOLOGY PROGRAM AUGUST 14, 1985 CONFERENCE CENTER, BUILDING 101 NATIONAL INSTITUTE OF ENVIRONMENTAL HEALTH SCIENCES RESEARCH TRIANGLE PARK, NORTH CAROLINA PEER REVIEW OF DRAFT TECHNICAL REPORT OF LONG-TERM TOXICOLOGY AND CARCINOGENESIS STUDIES BY THE TECHNICAL REPORTS REVIEW SUBCOMMITTEE AND PANEL OF EXPERTS TRANSCRIPT OF PROCEEDINGS Reported by: Margaret M. Powell/Court Reporter 2918 Barmettler Street Raleigh, North Carolina 27607 (919) 832-2284 SL 038421 1 2 APPEARANCES 3 Subcommittee Members 4 DR. JERRY B. HOOK 5 DR. FREDERICA PERERA 6 DR. JAMES SWEMBERG 7 Panel Members 8 DR. JOHN J. CROWLEY 9 DR. KIM HOOPER 10 DR. THOMAS C. JONES 11 DR. RICHARD J. KOCIBA 12 DR. DAVID KOTELCHUCK 13 DR. FRANKLIN E. MIRER 14 DR. I.F.H. PURCHASE 15 DR. STEVEN R. TANNENBAUM 16 DR. BRUCE TURNBULL 17 18 19 20 21 22 23 24 25 SL 038422 PAGE 2 1 2 3 CHEMICAL CONTENTS 4 Decabromodiphenyl Oxide 5 Ephedrine Sulfate 6 Diesel Fuel Marine/Navy Fuel JP05 7 Chlorinated Paraffins (C23' 40% Cl) 8 Chlorinated Paraffins (C^2* 58% Cl) 9 Tetrachloroethylene (Perchloroethylene) 10 Chlorendic Acid 11 n-Butyl Chloride 12 13 14 15 16 17 18 19 20 21 22 23 24 25 SL PAGE 3 PAGE 7 55 71 112 140 167 208 235 1 PAGE 4 2 PROCEEDINGS (8:30 a.m.) 3 CHAIRMAN HOOK: Good morning. Welcome. I'd like 4 to officially open the meeting of the Technical Reports Review 5 Subcommittee and Panel of Experts who are assigned tc be 6 counselors to the National Toxicology Program. I'm Jerry Hook, 7 Again, welcome to you all. We have a very busy day, and we 8 shall try to get through the agenda that you have in the order 9 of the chemicals to be reviewed today. Our goal is to end 10 around 3:30. I'd like for us to get through both chlorinated 11 paraffins by lunch, so you know roughly what our goal is. 12 I'd like to welcome the members of our panel. We 13 have one new and old member. Dr. Frank Mirer, who is Direct 14 of Health and Safety Department at the International Union 15 of United Auto Workers. He's joined us again. I recall that 16 he was going off as I came on the first time. We're glad to 17 have you. 18 One other new member of the Board, Dr. Bob Scala, 19 who is not with us today. 20 So as we begin, shall we introduce ourselves. 21 First the panel and then members of the audience so we'll a1' 22 know who we are. Dr. Purchase? 23 DR. PURCHASE: I'm Dr. Purchase from Imperial 24 Chemical Industries in the United Kingdom. 25 DR. HOOPER: Dr. Hooper, the State Department of SL 038*2Z* INTRODUCTIONS PAGE 5 Health in California. DR. CROWLEY: John Crowley, from The Fred Hutchinson Cancer Research Center in Seattle. DR. KOCIBA: Dick Kociba, Dow Chemical. DR. MIRER: Frank Mirer, still from the UAW. DR. SCHWET2: Bernie Schwetz from NIEHS, NTP. DR. RALL: Dave Rail, NIEHS, NTP. DR. HART: Larry Hart, NIEHS, NTP. CHAIRMAN HOOK: I'm Jerry Hook. I work at Smith Kline and French Labs. DR. MCCONNELL: I'm Gene McConnell, NIEHS, NTP. DR. MATTHEWS: Skip Matthews, NIEHS, NTP. DR. HUFF: James Huff, NIEHS, NTP. DR. PIEGORSCH: (Arthur) Piegorsch, NIEHS, NTP. DR. BOORMAN: Dave Boorman, NTP. DR. SWENBERG: Jim Swenberg, CUT. DR. TURNBULL: Bruce Turnbull, Cornell University DR. KOTELCHUCK: Dave Kotelchuck, Hunter Graduate School. DR. JONES: Carl Jones, Harvard Medical School. DR. PERERA: Frederica Perera, Columbia Universit (Appearances from the Audience.) CHAIRMAN HOOK: Thank you very much. As we begin our discussion today, we'll ask Dr. McConnell if he has any Si 038^25 1 INTRODUCTIONS PAGE 6 2 comments in general before we start. 3 DR. MCCONNELs No. 4 CHAIRMAN HOOK: Dr. Huff? 5 DR. HUFF: No. 6 DR. HART: We just need to announce to our 7 audience that we're taping this meeting. So please speak as 8 clearly as you can. If you're speaking out here from the 9 chairs on the side, please use the microphones on the side 10 or the one by the podium and identify where you're from. 11 Thank you. 12 DR. TANNENBAUM: I'm Steve Tannenbaum from MIT. 13 CHAIRMAN HOOK: I'm sorry, Steve, we missed you/ 14 Steve Tannenbaum. 15 Now we're ready to go. To remind you of our 16 procedures, as we begin each chemical the chemical manager 17 will be sitting at the head table and will review the study 18 in general, provide the final summation of the conclusions. 19 We then have from two to four reviewers on each compound. We 20 will go through the reviewers as they're listed on the program 21 and then we will carry on our debate and discussions and reach 22 a conclusion. On occasion members of the audience will be 23 allowed to make comments. It's my understanding that on one 24 of the compounds after lunch there is at least one individual 25 with some prepared comments. SL 038426 1 DECABROMODIPHENYL OXIDE PAGE 7 2 We are ready to begin then with the first 3 chemical. It's decabromodiphenyl Oxide. Dr. Matthews is the 4 chemical manager. Skip? 5 CHEMICAL MANAGER: Decabromodiphyenyl oxide is 6 a completely (bromade) aromatic ether used as a flame redar- 7 dant and plastic resin for synthetic fibers. Production 8 figures are currently estimated at somewhere around or above 9 ten million pounds per year. It has not been reported as an 10 environmental contaminant. Human exposure is largely limited 11 to production and use. 12 In a health survey of people involved in produc 13 tion and use there were some mild health symptoms reported, 14 apparently nothing serious, and it wasn't sure whether these 15 symptoms were due to decabromodiphyenyl oxide or to previous 16 exposure to (polybromine ) at the same plant. 17 This chemical has low animal' toxicity. Doses up 18 to two thousand milligrams per kilogram resulted in no acute 19 toxicity. Repeat dose studies resulted in mild lesions in 20 liver, kidney and thyroid. This chemical is not ( ogenic) 21 and it's not mutagenic in cell ( 22 ) not mutagenic in mouse lymphoma assay, and 23 did not cause sister chromotid exchange or aberrations in 24 Chinese mouse ovary cells. 25 It was not reported or found not to be St 1 DECABROMODIPHENYL OXIDE PAGE 8 2 carcinogenic in a previous study using Sprague-Dawley rats 3 in doses from .01 and 0.1 and 1.0 milligrams per kilogram per 4 day. The chemical was nominated to the NTP and studied as 5 part of the class study in flame retardants. 6 In this study, the fourteen-day and thirteen-week 7 studies failed to detect any compound-related effect when 8 administered at the maximum doses. Therefore, in the two- 9 year study doses were set at fifty thousand parts per million 10 as one-half, MTD and MTD, twenty-five thousand parts per 11 million. 12 The results of these studies indicate that 13 survival and body weight were unaffected in rats, except foz^H 14 low-dose males, and this became significantly different only 15 in the last two weeks of the study. And it's probably not 16 compound-related. 17 In mice survival of control males was decreased 18 quite a bit. This is presumably due to fighting. Body weight^ 19 in the males were unaffected. 20 Conclusions coming from this study were that some 21 evidence of--that there was some evidence for carcinogenicity 22 in male and female rat liver as evidenced by increased 23 incidence of neoplastic nodules in the liver. And there was 24 equivocal evidence of carcinogenicity in male mice as evidenced 25 by increased incidences of hepatocellular adenoma and SL 038A28 1 1 TETRACHLOROETHYLENE PAGE 167 2 AFTERNOON SESSION (1:33p.m.) 3 CHAIRMAN HOOK: Shall we reconvene? 4 For those of you who weren't here this morning, 5 our procedure is to identify the compound and the chemical 6 manager. The chemical manager will review the study for us. 7 Then our principal reviewers will present their comments. 8 And in the case of our first chemical we will have some 9 comments from the audience. And then the chemical manager 10 will respond, and then we will open the panel up for 11 discussion. 12 The first chemical compound is Tetrachloroethylene, 13 Perchloroethylene. Dr. Mennear? 14 ' TETRACHLOROETHYLENE 15 CHEMICAL MANAGER: Tetrachloroethylene, also 16 commonly referred to as perchloroethylene, or PERC, is an 17 industrial solvent used in a variety of processes such as 18 metal degreasing and dry cleaning. 19 In 1983, two hundred and fifty kilograms of tetra 20 chloroethylene were produced in the United States. It has 21 been estimated that eighty-five percent of the tetrachloro 22 ethylene used annually is lost to the atmosphere. I 23 PERC was nominated because of its widespread 24 industrial use and because of the potential for human exposure. 25 NIOSH estimated that approximately five hundred thousand PE NU AD CO.. SACONHE. H J. 07002 SL 038429 i 1 TETRACHLOROETHYLENE PAGE 168 2 Americans are exposed to this chemical in the workplace. 3 Our studies of the toxicology and carcinogenicity 4 of ninety-nine percent pure tetrachloroethylene were conducted 5 by exposing Fisher 344 rats and B6C3F1 mice to air containing 6 tetrachloroethylene which was stabilized with N-methyl- 7 morpholine for six hours a day five days per week for 103 8 weeks. The exposure concentrations used in the chronic study 9 were 0, 200 parts per million and 400 parts per million for 10 rats and 0, 100 and 200 parts per million for mice. These 11 doses were selected on the basis of the results of thirteen- 12 week inhalation studies also conducted in rats and mice. 13 In these thirteen-week studies, 1600 parts per 14 million of tetrachloroethylene was found to be lethal to a 15 few of the male and female rats and mice. In rats, doses 16 of 200 parts per million or more produced minimal to mile 17 hepatic congestion. In mice, 200 parts per million or more 18 caused minimal to mild liver and kidney changes. Liver change 19 included leukocytic infiltration, centrolobular necrosis, 20 bile statis and mitotic alterations. Kidney changes were 21 karomegaly of the tubular epithelial cells. 22 During the two-year studies, body weight gai ? 23 for dosed rats and mice were essentially similar to those 24 of the control animals. The survival of male rats dosed with 25 400 parts per million of tetrachloroethylene was significantly SL 038430 1 TETRACHLOROETHYLENE PAGE 169 2 reduced. This decreased survival may have been related to 3 an increased incidence of mononuclear cell leukemia in dosed 4 males. 5 There was a compound-related increase in the 6 number of early deaths that were attributed to mononuclear 7 cell leukemia while deaths among the male rats from other 8 causes remained unchanged. The survival of dosed female rats 9 was not affected by tetrachloroethylene. 10 The survival of both groups of dosed male mice 11 was reduced relative to controls; however, untreated control 12 survival in this study was unusually high with ninety-two 13 percent of the animals living until the scheduled termination 14 of the study. Exposure to 200 parts per million significantly IS reduced the survival of female mice. The early deaths among 16 both male and female mice may have been influenced by the 17 development of hepatocellular carcinoma. 18 Both exposure concentrations of tetrachloroethylene 19 were associated with increased incidences of mononuclear cell 20 leukemia in male and female rats. In females both concentra 21 tions reduced the time to the diagnosis of the tumor. 22 Tetrachloroethylene caused renal tubular cell 23 karyomegaly in both male and female rats and renal tubular 24 cell hyperplasia in males. There was also an increase in 25 renal tubular cell adenomas and adenocarcinomas, combined. SL 38A3l 1 TETRACHLOROETHYLENE PAGE 170 2 in dosed male rats. The renal changes have been consistently 3 found in our earlier chronic studies of chlorinated ethanes 4 and tehylenes. 5 Four high-dose male and two high-dose female rats 6 had gliomas of the brain, but one control male and one control 7 female also had the tumor. 8 In both male and female mice, exposure to tetra- 9 chloroethylene caused increases in hepatocellular neoplasms, 10 with increases in the incidences of both adenomas and 11 carcinomas being detected in males and increases in carcinomas 12 being detected in females. 13 Tetrachloroethylene also caused renal tumbular 14 cell karyomegaly in both sexes of mice, and one low-dose male 15 also had a renal tubular cell adenoma. 16 There were no neoplastic changes in the respiratory 17 tracts of either rats or mice, but there'was an increased 18 incidence of squamous metaplasia in the nasal cavities of 19 dosed male rats. 20 There was no evidence of mutagenic activity for 21 tetrachloroethylene when it was tested with or without j I 22 activation in four strains of salmonella. Tetrachloroethylene 23 was also inactive in the mouse lymphoma, Chinese hamster 24 ovaries, sister chromatid exchange and drosophila tests. 25 During the audit of the data of this study, a SL 038432 1 TETRACHLOROETHYLENE PAGE 171 2 few untrimmed lesions were found. All were adequately 3 resolved and had no impact on the interpretation of the 4 results. 5 Under the conditions of these inhalation studies, 6 there was some evidence of carcinogenicity of tetrachloro7 ethylene in F344 rats as shown by increased incidences of 8 mononuclear cell leukemia in males and female and renal 9 tubular cell neoplasms in males. There was clear evidence 10 of carcinogenicity in B6C3F1 mice as shown by increased 11 incidences of both hepatocellular adenomas and carcinomas 12 in males and of hepatocellular carcinomas in females. 13 CHAIRMAN HOOK: We'll begin with our reviews. Dr. 14 Swenberg? 15 DR. SWENBERG: I thought this was a well-written 16 Report of a well-conducted study on tetrachloroethylene. It's 17 encouraging to see this one compared to-the gavage studies. 18 Items that should be discussed prior to the 19 acceptance of the Report include the following: 20 On page 16 there should probably be some mention 21 of tetrachloroethylene as a ground water contaminant. That's 22 one of the most common routes of human exposure, albeit low 23 doses. 24 Pages 53 and 84 refer to renal lesions and comment 25 on their likeness to the hydrocarbon-induced nephropathy. SL 038433 1 TETRACHLOROETHYLENE PAGE 172 2 X think that in order to make this correlation some additional 3 work will be necessary. This will be the staining of sections 4 for hyaline or protein droplets that are characteristic of 5 hydrocarbon nephropathy. It's my understanding this is under 6 way. If they are present, then their conclusion is supported. 7 If they are not present, I'm afraid it's rejectable. 8 Page 54 and the Abstract should clearly point 9 out that the renal tumors present in the rats were not 10 statistically significant, but that similar lesions have been 11 noted in the prior gavage studies. 12 Page 57. I questioned the statistics that were 13 present on interstitial cell tumors of the testicles. It 14 seemed highly unlikely to have values of .001 for such small 15 differences, but maybe I'm wrong. 16 Page 58. The thromboses that were observed in 17 the nasal cavity are most likely secondary to mononuclear 18 cell leukemia. We've noted a very high incidence of this 19 lesion in nasal cavities of leukemic rats and have never seen 20 it in non-leukemic rats. So I'd like to see the records of 21 the gross or the other lesions reviewed in that regard. 22 To get into two of the more substantial aspects 23 of this, I think the Report should very clearly state that 24 the interpretation of mononuclear cell leukemia is really 25 based on the standard method of data evaluation and that it's SL 038434 1 TETRACHL0R0ETHYLENE PAGE 173 2 additionally supported by the dose-response effect on tumor 3 latency and the staging evaluation. The tumor latency data 4 should include the mean latency by dose group for animals 5 dying prior to the terminal sacrifice. 6 And I think it should also point out that this 7 staging effort is really a preliminary effort and may require 8 additional refinements. We have to find out if it really 9 is giving us meaningful data before we hang our hat on it 10 very strongly. 11 The Stromberg and Vogtsberger paper was cited 12 in this Report saying that mononuclear cell leukemia has a 13 course of two to six weeks. And I think if that in fact is 14 the case, then staging is really irrelevant. That citation, 15 by the way, was incomplete and could not be referred to by 16 anyone the way the report was. You need to get that citation i 17 in there. X at o 18 The discussion of this Technical Report should 9 S. 19 be expanded to discuss possible mechanisms of carcinogenesis P tttb A U CO. ZATONNC, N J. 07002 S 20 of tetrachloroethylene. In particular, it should point out Z o : 21 that the mutagenicity studies were negative and that it o w 9 5 22 caused tissue toxicity at the same site as neoplasia in at & 23 least two of the three tissues, i.e, the mouse liver and 24 the rat kidney. 25 And IX don't think we really have a good handle 1 TETRACHLOROETHYLENE PAGE 174 2 on whether it's caused a similar type of lesion in the immune 3 system of the rat. This is somewhat of a difficult tissue 4 to evaluate from the pathology standpoint for toxicity. But 5 I know the NTP has an immunotox program, and I would strongly 6 recommend that this compound be examined by them for its 7 effect on immunotoxicity. 8 The particular endpoint we're talking about here-- 9 that being mononuclear cell leukemia--has one of the sharpest 10 age response incidences for tumor induction of any endpoint 11 I know of. And if we were affecting the age of the tissue 12 through toxic responses, we might see this kind of response^ m 13 So I think it is a very important project for future work 14 of the NTP. 15 I think those are the only comments I have. I 16 basically agree with the conclusions of the draft Technical 17 Report. 18 CHAIRMAN HOOK: Thank you. Dr. Mirer? 19 DR. MIRER: I also thought this was a well- 20 conducted, very important study. I will want to talk about 21 the conclusions at the end. 22 Under Editorial Comments: 23 The OSHA limit for perchloroethylene is incorre 24 stated on page 16, it's a hundred parts per million, which 25 is equal to 680 milligrams per cubic meter, not fifty parts I 1 TETRACHLOROETHYLENE PAGE 175 2 per million as stated in the introduction. That latter number, 3 the fifty parts per million number, is a NIOSH-recommended 4 limit. And I guess I should say that although it is generally S inapproprite to discuss considerations for human risk in 6 these Reports, the fact of testing a substance at the existing 7 exposure limit and finding a substantial effect at that level 8 ought to be noted. 9 Throughout the introduction, doses are quoted 10 in a variety of units. For example, dry cleaning exposures 3 11 are quoted in mg/M m all other inhalation exposures in parts 12 per million. And I think it would be helpful to convert these, 13 And also to attempt to estimate the dose perchloroethylene 14 in rats and mice in milligrams per kilogram per day. This 15 would permit some quantitative comparisons of the results 16 of the gavage and inhalation studies and eventually compari 17 sons to the human exposure levels. 18 Under non-tumor pathology, to repeat my previous 19 theme, the summary should place greater emphasis on the doses 20 associated with the appearance of non-tumor pathology. Kidney 21 lesions at two hundred parts per million exposure in male 22 and female rats and other lesions of male and female mice 23 at a hundred parts per million, together with the failure 24 to demonstrate a no-observed-effect level for these pathlo- j 25 logical changes should be pointed out. Si 3843? 1 TETRACHLOROETHYLENE PAGE 176 2 In addition, the text now associates these effects 3 with a range of doses, especially in the thirteen-week studies 4 without making a call at what level of exposure they first 5 appear. 6 Now, back to semantics. Under conclusions, I 7 agree with the conclusions of "clear evidence of carcino 8 genicity in both sexes of mice." I also think the conclusion 9 should indicate "clear evidence" of carcinogenicity in male 10 and female rats to be consistent with the definitions of these 11 categories. The neoplasm is malignant. It is present in 12 increased incidence, and the increase in this study appears^^| 13 to be chemically related by all the usual criteria. 14 The use of the life table test for statistical 15 analysis is well justified by the text and is, therefore, 16 judged appropriate. In the alternative, should the previous 17 method of non-time dependent pairwise comparison be used, 18 elevations were significant by trend test and marginally 19 significant in pairwise comparisons; for female rats elevation^ 20 were statistically significant by trend test and in pairwise 21 comparisons using the late, lamented Benferroni inequality 22 criterion. 23 The finding is apparently viewed as less 24 convincing because control animals in this group showed a 25 high rate of mononuclear cell leukemia compared to historic 038^38 Si* 1 TETRACHLOROETHYLENE PAGE 177 2 controls. Despite this, rates of tumors in the treatment 3 groups were significantly elevated over the concurrent control 4 and presumably markedly higher than historical controls. Thers 5 is no biological or other explanation advanced for using a 6 high incidence in controls to discount the significance of 7 elevations in the treated animals. Indeed, the historical/ 8 concurrent control argument is usually stated in the other 9 direction. 10 The increased incidence which appears in the crude 11 analysis persists when the exercise is extended by staging 12 and comparing groups by time of death. This analysis should 13 lend additional weight to the finding. And I add that it 14 would be desirable to add statistical tests to the data on 15 Table 25, page 77. 16 The leukemia evidence is bolstered by the presence 17 of renal tubular cell adenomas and carcinomas in male rats. 18 These rare tumors would alone constitute some evidence of 19 carcinogenicity in male rats. 20 Therefore, I do not agree with the conclusion 21 regarding the level of evidence in rats. Although I should 22 say that this "clear" versus "some" debate, which is new to 23 me this term--I'm quite clear where we're going with that 24 today. (Spontaneous discussion.) 439 i i I t TETRACHLOROETHYLENE PAGE 178 2 CHAIRMAN HOOK: I think we're going in circles. 3 Thank you, Dr. Mirer. Dr. Turnbull? 4 DR. TURNBULL: Well, my first comment was just S to remark that there is no sentinel animal in this study. 6 My next remark concerns historical rates. And 7 this has come up with leukemias. And the first point about 8 that is a generic one that, for instance, in the analysis 9 on page 52, leukemias for the rats, it states, "Historical 10 incidence of, say, twenty-seven percent plus or minus nine 11 percent." It wasn't clear to me whether that was one standard 12 deviations, two standard deviations or extremes experienced 13 in the historical studies. 14 It turns out from Appendix F that it is in fact 15 one standard deviation. So the range could even be bigger 16 than what's seemingly suggested by twenty-seven plus or minus 17 nine. 18 Also, with these historical controls, I'm not 19 sure what the fair comparison is, whether, for instance, we 20 should have--one historical comparison might be just with 21 control groups in inhalation studies. Just as perhaps with 22 a dermal study, one historical control group for comparison should be other skin painting studies rather than just all control groups. That leads on to my next point. iApparently, thesrree SL 038440 1 TETRACHLOROETHYLENE PAGE 179 2 was another concurrent control group going on at the same 3 time in the same lab, also an inhalation study. That was 4 the one we reviewed last time, methylene chloride. These 5 are very insensitive screens that we're doing. And I'm always 6 looking for more power. 7 One way to do that would be to include this 8 second concurrent control group if that's fair. It s emed 9 that conditions were right. This is the same time and the 10 same lab. But apparently it might have been a different 11 pathologist. I don't know what that means when it's a 12 different pathologist. I had hoped that with the reviews 13 and the coded readings and the PWG and everything, that that 14 would somehow control the interpathologist variability, but 15 maybe someone can put me right on that. 16 Anyway, if you do, then I asked NTP to do the 17 analysis. It was just given to me five minutes ago, and I'm 18 not sure whether there are any differences or not. I haven't 19 been able to assimilate this work using the larger--the 20 enlarged--data. 21 Anyway, even if you don't agree with including 22 it as a concurrent control group, then perhaps it should have 23 been included in the historical data base. Because it is 24 history, it has been approved, and we only have two inhalation 25 historical groups. And all the rest of the thousands of 1 TETRACHLOROETHYLENE PAGE 180 2 animals were not inhalation studies from what I understand. 3 I don't know whether that makes a difference or not. 4 Certainly, I would think it would make a difference in skin 5 painting vehicle controls. 6 Okay. The high incidence of leukemia in control 7 rats--now this is very similar to that first chemical that 8 we reviewed today, the decabromodiphenyl oxide, which also 9 had a high incidence of leukemia in the rats if X recall 10 right. There, in the study, NTP tried to play down the 11 statistical significance because it was an abnormally high 12 rate. No such attempt to downplay the significance was don 13 in this Report, although it seems to me that there was 14 randomization going on here. There was uniformity of 15 pathology. So it should be fair enough just to compare the 16 groups here. 17 I would like to know what the incidence was of 18 leukemia in the methylene chloride, control group. X don't 19 have that with me. Is that available? 20 CHEMICAL MANAGER: I don't remember the exact 21 number, but it was within two percentage points. 22 DR. TURNBULL: So it's very close to this? 23 DR. HUFF: Yes, it is. 24 CHEMICAL MANAGER: Yes. 25 DR. TURNBULL: So I'm almost prepared to forget TETRACHLOROETHYLENE PAGE 181 the low--I don't think this is a point, the high rate of control leukemias. (COMMENT): The control was sixty-eight percent. DR. TURNBULL: Sixty-eight percent in the methylene chloride? So I think this is a fair analysis here. I agree with Dr. Mirer on the point he was making about the leukemia in rats. This special analysis on staging of leukemia, I'm a little skeptical about it. It does look a little bit like data dredging to me, so I would downplay those P-values some for that special analysis. CHAIRMAN HOOK: Thank you. Dr. Jones? DR. JONES: I think almost everything I was going to say has been said. Essentially, I agree with the conclu sions of the Report. There are a couple of editorial and other comments I would like to make. The first thing I noticed, as I had noticed in quite a few of the Reports, there seems to be no clear correlation between the results of the mutagenicity tests and the bioassay tests. And I missed a meeting, and I wonder if such a study of these correlations have been made, and has it been presented to this group? If so, I missed it. CHAIRMAN HOOK: It wasn't presented here; I believ SL 038443 1 TETRACHLOROETHYLENE PAGE 182 2 it was presented to the Board. 3 DR. JONES: Has that been published? Can we get 4 anything on it? 5 DR. MCCONNELL: We will take care of getting you 6 some of the publications on that. 7 DR. JONES: I'd be very much interested in that. 8 I think that we have sort of passed over that as we've gone 9 along, but it seems to me it's something we probably should 10 notice. 11 From an editorial standpoint, I noticed that many 12 of the reference citations are incomplete, as they were in 13 many of the Reports today. I don't know whether that's a 14 code, you have some way of picking these up later on or whar 15 happened. And I know that you couldn't find those references 16 when they just had the year and the name of the person. Is 17 it intended that they're going to be completed later? 18 CHEMICAL MANAGER: Oh, yes. They will be 19 completed later. The material is all sent out of town for 20 typing and putting into this final form. And the contractor 21 who does it has been instructed not to try to complete a 22 reference until they have the hard copy in their hands. Some 23 times it will be the chemical manager who is negligent and 24 doesn't get the hard copy to the people who are typing these 25 reports. That's why some of them are incomplete. SL 03844* 1 TETRACHLOROETHYLENE PAGE 183 2 DR, JONES: It's been my experience that if you 3 dump a lot of sand in the stream, it's very hard to get it 4 all out downstream a mile or so. I hope it doesn't come to 5 that. 6 (Spontaneous discussion.) 7 DR. JONES: Concerning the conclusions, I point 8 out that the first sentence--and I'll read it: "Under the 9 conditions of these inhalation studies, there was some 10 evidence of carcinogenicity of tetrachloroethylene in F344/N 11 rats as shown by an increased incidence of mononuclear cell 12 leukemia in males and female and rare renal tubular cell 13 neoplasms in males." 14 Now I assume that that sentence means that the-- 15 there's two bits of information. The renal cell tumors and 16 the mononuclear cell leukemia. Those two factors were the 17 reason for saying that there was "some evidence." It wasn't 18 one or the other, it was both of them. That's the way I read 19 it. I assume that's the way it was intended. 20 And I have no more comments to make on this very 21 excellent Report. 22 CHAIRMAN HOOK: Thank you. 23 The Halogenated Solvents Industry wants to 24 respond to the study. You all have copies of their written 25 comments. And I believe that we have a representative who SL 038445 1 TETRACHLOROETHYLENE PAGE 184 2 wants to make some comments to us now. 3 DR. ROBINSON: Good afternoon. My name is 4 Thomas Robinson of Vulcan Chemicals, and I dm here to speak 5 on behalf of the Halogenated Solvents Industry Alliance 6 regarding the recent draft Technical Report for perchloro7 ethylene inhalation bioassay. You have already received a 8 copy of our written comments and consequently I will keep 9 my remarks brief. 10 I do wish to point out that on Table 3 of the 11 written comments, the last entry under female rats should 12 read eighteen out of fifty, not fifteen out of fifty. 13 Of major concern is the NTP's finding of "some 14 evidence of carcinogenicity of tetrachloroethylene in 15 Fischer 344/N rats as shown by increased incidences of mono 16 nuclear cell leukemia in males and females..." 17 We do not believe that such a finding is warranted 18 based on our brief review of the Technical Report and its 19 underlying data. Although there is an equally increased 20 incidence of leukemia in dosed female rats, the incidence 21 of mortality at both dose levels is the same as in untreated 22 controls. Further, the number of animals and the number of 23 leukemias for all dose levels at terminal sacrifice were 24 essentially the same. 25 A similar lack of correlation of mortality with SL 038446 1 TETRACHLOROETHYLENE PAGE 185 2 with the incidence of leukemia is also seen in the male rat. 3 Even though the high dose male rat had a higher early mortality 4 than the low-dose animals, the incidence of leukemia was 5 essentially the same for both dose levels. In contrast to 6 this observation was an equivalent early mortality in both 7 untreated and low-dose animals. 8 There are two additional issues which must be 9 considered regarding the association of mononuclear cell 10 leukemia with exposure to perchloroethylene. There was an 11 unusually high incidence of leukemia in control animals in 12 the perchloroethylene bioassay. In both male and female rats, 13 the rate of leukemia is more than twice that seen in historica!. 14 controls for the NTP program. 15 In fact, the incidence of leukemia in male rats 16 reached a record high fifty-six percent, which was ten 17 percentage points above the NTP's previous upper bound as 18 contained in the draft Technical Report. 19 It is important to note that in the methylene 20 chloride study, the incidence of leukemia in male control 21 rats was sixty-eight percent. Moreover, the Battelle propylene l 22 and propylene oxide studies had a leukemia incidence in male 23 rat controls of thirty-two percent and forty percent 24 respectively. This high and apparently increasing incidence 25 in Battelle controls raises questions as to the ability to SL 38447 1 TETRACHLOROETHYLENE PAGE 186 2 draw any conclusions from the perchloroethylene study 3 relative to the incidences of leukemia as evidence of 4 carcinogenicity. 5 The second issue is of even greater significance 6 since it may have long-term implications for the NTP bioassay 7 program. This study is the first to base a conclusions, at' 8 least in part, on the staging of mononuclear cell leukemia 9 in Fischer rats. The staging of leukemia and other cancer 10 is for the assessment of the degree of neoplastic progresssion 11 Staging requires knowledge of the biological course of the 12 cancer and a correlation of the morphological findings witl^^ 13 duration of the disease and the severity of the effects. 14 The biological course of the Fischer rat 15 leukemia is not well understood and it is questionable whether 16 the current staging method used by NTP actually reflects this 17 correlation. Some examples of the perceived deficiencies 18 in the current staging method were given in our written commenf 19 and need not be addressed here other than to say they exist. 20 To insure the proper interpretation of the 21 significance of mononuclear cell leukemia in the perchloro 22 ethylene study and in future bioassays, staging criteria must 23 be established which will reflect as closely as possible 24 disease duration and the extent of progression. Therefore, 25 we propose the co-sponsoring with NTP of a panel of experts SL 038448 1 TETRACHLOROETHYLENE PAGE 187 2 in Fishcer rat leukemia to develop an appropriate staging 3 scheme and to evaluate the rat leukemia pathology in the 4 perchloroethylene study. 5 Unless the significance of the mononuclear cell 6 leukemia is established by a valid staging scheme, we are 7 concerned that the current procedure may set a precedent that 8 will undermine the objective evaluation of this and of future 9 bioassays. 10 The NTP ocncluded that there was "some evidence 11 of carcinogenicity" in male rats based on a slight increase 12 in kidney tumor pathology; however, the incidence of combined 13 adenomas and adenocarcinomas was not statistically significant. 14 Perhaps this finding has some other explanation related to 15 the in-life phase of the study. Moreover, due to the brief 16 interval between the issuance of the draft Technical Report 17 and today's meeting, we were unable to examine in any detail 18 the mouse portion of this study. 19 Althoug we're aware that an audit of the 20 perchloroethylene inhalation bioassay has been conducted by 21 Dynamic Corporation, HSIA will also conduct its own audit 22 of this study. 23 Regarding the issue of mononuclear cell leukemia 24 in the rat, we urge the development of a suitable staging 25 scheme for this lesion by an expert panel. Further, based SL 038449 1 TETRACHLOROETHYLENE PAGE 188 2 on the lack of correlation of the incidence of leukemia with 3 mortality, and more importantly, the extremely high incidence 4 of leukemia in Battelle controls, we believe that a finding 5 of "some evidence of carcinogenicity" is NOT warranted. The 6 present data is inadequate to establish the significance of 7 the incidence of leukemia relative to perchloroethylene 8 exposure. 9 We appreciate the opportunity to make this 10 presentation to the Board of Scientific Counselors, and I 11 will attempt to answer any questions. Thank you. I also 12 have additional copies of our written comments should some 13 like to have one. 14 CHAIRMAN HOOK: Thank you. 15 At this time I should say that this is the only 16 request from someone to make comments from the audience. We 17 will take other contributions from the audience at this time. 18 (No response.) 19 CHAIRMAN HOOK: There being none, then Dr. Mennear 20 respond, if you would, to the Panel. 21 CHEMICAL MANAGER: All right. I think many of 22 the concerns voiced by the reviewers as well as by Dr. 23 Robinson overlap, so I'll not try to differentiate who brought 24 what up, but just comment on these things as we go along. 25 First of all, I want to point out or agree that^^^ SL 038450 1 TETRACHLOROETHYLENE PAGE 189 2 we should not make a conclusion of presence or absence of 3 carcinogenicity based upon staging of the leukemia in and 4 of itself. As Dr. Robinson noted, we are simply at the 5 beginning stages of this kind of diagnosing. 6 But I also want to point out that if you look 7 at the statistical tables, our routine statistical tests 8 do indeed show statistically significant increases in the 9 incidences of mononuclear cell leukemia in these animals. 10 One of the things that we thought we wanted to 11 do was go in and look more closely at this. So we're using 12 the staging, the special Kaplan Meirer curves, special Kaplan- 13 Meirer curves, that we put in the discussion section. We're 14 using all of this as a way of trying to understand better 15 what the data is trying to tell us. 16 And as we have gone through, one of the things 17 that the data seems to be telling us is that, indeed, in the 18 female rat exposure to tetrachloroethylene the animal 19 develops mononuclear cell leukemia earlier. Now, it's also 20 been pointed out that it seems strange that if we've got more 21 mononuclear cell leukemia in the female rats, we should also 22 have a greater incidence or effect on survival. And in the 23 case of female rats, survival was the same in the dosed groups 24 as it was in the control groups. 25 We went back and began looking at what the SL 038451 1 TETRACHLOROETHYLENE PAGE 190 2 pathologists diagnosed as the cause of death of these animals. 3 And we found some rather interesting data. 4 Considering only the early-death animals--by the 5 way, I'm trying to articulate this without going back to my 6 old trick of using the overhead projector. If I can't get 7 it out in words, I've got the data on an overhead, and you 8 can look at the numbers. 9 But what was found was when the mononuclear cell 10 leukemia was considered to be the primary cause of death in 11 these female rats, we got a dose-related increase in the 12 incidence of death considered to be due to mononuclear cel 13 leukemia. The incidence was 8, 18 and 20 in animals dying 14 primarily due to mononuclear cell leukemia. 15 And we started wondering what happened to the 16 other deaths. And as we looked at what some of these other 17 deaths in the control animals--what were' the primary causes 18 of other deaths in the control animals--we found two categorie 19 that particularly stuck out. 20 One was animals that died from pituitary adenomas 21 or pituitary carcinomas. And we found that in our control 22 group six animals died in this category. In our low-dose 23 group we had only two animals die in this category. In our 24 high-dose group we had only one animal die in the category. 25 Another cause of death that stuck out was anima^h 038*^2 si* 1 TETRACHLOROETHYLENE PAGE 191 2 that had to be killed for humanitarian reasons because of 3 large mammary gland or (clitorol) gland tumors. Again, we 4 found six animals in the control group that were killed 5 early. And these deaths, these early terminations, were 6 between weeks 84 and 98 of the study. So they were rather 7 late in the study. 8 In the low-dose animals we found only four 9 animals that had to be killed early, and in the high-dose 10 group we found three animals that had to be killed early. 11 Now, this raises an obvious question. Does 12 tetrachloroethylene protect against pituitary tumors and 13 mammary tumors and that sort of thing? And the answer is 14 no. If we go through and irregardless of what the primary 15 cause of death in these animals might have been, if we just 16 total up the number of animals that had pituitary tumors and 17 total up the number of animals that had the mammary or the 18 (clitorol) gland tumors, we find that across the board all 19 animals--that the animals had the same rate. 20 So the conclusion that we've come to here is that 21 the mononuclear cell leukemia in the female rats is causing 22 the death of these animals before these other tumors can 23 develop to a stage sufficient to kill the animals. 24 If you look at the median time to death of the 25 early-death animals and the diagnosis of mononuclear cell Si 38453 1 TETRACHLOROETHYLENE PAGE 192 2 leukemia, we find that the median time to the diagnosis in 3 the controls was 98 weeks, the median time to the diagnosis 4 in the low-dose animals was 87 weeks, and the median time 5 in the high-dose animals was 89 weeks. 6 I think that an important question that came up 7 is this business about the historical incidence of mononuclear 8 cell leukemia. And we struggled with this also. And Dr. 9 Rao of the NTP has got some information that we would like 10 for him to share with you on the historical rates. 11 CHAIRMAN HOOK: Well, very quickly. We've gone 12 through it once today. Very quickly. 13 DR. RAO: Well, I would rather use an overhead 14 projector so it will be clear and can be done faster than 15 rattling off some numbers. 16 Let me pass out some of the tables quickly so 17 you will have them also. 18 Specifically, I wanted to show you the incidence 19 of mononuclear cell leukemia in inhalation studies. Some 20 months ago when we started seeing (the increase in ) 21 incidence, we were puzzled too and wondered what is happening. 22 So to really get a handle on this, we took mainly 23 the inhalation study to address that, the present Report. 24 You can see we have a 1981 Report (indicating an average of 25 thirty-five percent). But if we take the 1983 necropsies-- 038^ SL 1 TETRACHLOROETHYLENE PAGE 193 2 we're going by the year of necropsy. The incidence was 52, 3 and then in 1984 we have some studies. Fifty-nine in the 4 male. And we do not have any studies available that were 5 necropsied in 1982. And that really indicates a dramatic 6 jump or increase in 1983. But the number of studies are so 7 few we cannot really draw a conclusion on what has happened. 8 Is there a change in environment, animals, 9 procedures, whatnot? So we had to take some other data base, 10 proceed on that and try to get a different handle on that 11 one. 12 Here we have a series of studies, dose feed, 1980 13 necropsies of the male rats, getting a twenty-seven percent 14 average. In 1981, twenty-six percent average. And then in 15 1982 necropsies we see a quick change happening right here, 16 and I included two arrows. I will explain what that is. And 17 then 1983, forty-five and forty-nine percent. 18 Look back at the source of the animals. The 19 animals were not (redivided). And for most of these studies 20 the sources are the same, Charles River or Kingston, where 21 the foundation animals are the same. 22 And also this arrow indicates there is a change 23 here. The commercial diet, we started the NIH07 diet here. 24 To resolve this question of why, even with the NIH07 diet, 25 the two studies, all of them with less than forty percent Si 38455 1 TETRACHLOROETHYLENE PAGE 194 2 incidence whereas these are more than forty percent, we 3 selected this study and this study and restaged them. And 4 we staged--looked at two pathologists together. S We found that this represented a truly stage 6 three or advanced case of leukemia. But our (presents) showed 7 up as twenty-two and the ( ) pathologist was twenty- 8 four. 9 When we looked at this one, stage three or 10 advanced case, was studied, six percent. And then stage two 11 or the clear evidence of the lesion was the other thirty 12 percent. 13 So this represented more an addition about at 14 stage two and stage three. And this change happened--in 15 October of 1982 we had a conference on hematopoietic tumors. 16 And in that there was considerable presentations, discussions 17 on mononuclear cell leukemia. 18 These are necropsies of the June-July time period, 19 probably right after the conference. From then on we have I 20 a change in the incidence reported. Not really, actual change 21 in the animal or the actual incidence of the lesion. I 22 So that gave us an adequate indication at this 23 point that there is no real change in the animal or the 24 environmental conditions. Except because of the increased j j 25 awareness of the pathologists as well as some criteria set ! SL 038456 1 TETRACHLOROETHYLENE PAGE 195 2 forth for diagnosing the lesion, they are including additional 3 cases. 4 CHAIRMAN HOOK: Thank you very much. Are there 5 any questions specifically for Dr. Rao? Dr. Purchase? 6 DR. PURCHASE: I didn't quite understand. 7 You said that you compared two studies? One with 8 a twenty-four percent incidence, one with a sixty percent. 9 Did the pathologists go back and reread the twenty-four 10 percent study? 11 DR. RAO: We have the slides available. Two 12 pathologists--we went back, looked at all the slides. We 13 have restaged them, stage two, stage three. Stage three, 14 that's the ( ) case. It agreed with the 15 original pathologist. Plus, we have forty other percentile, 16 forty more of twenty other animals with stage two which are 17 not included in the original. 18 DR. PURCHASE: So the percentage went up sixty 19 percent? 20 DR. RAO: Went up to the sixty-six area. It's j 21 approximately the same as others. I 22 DR. JONES: Do I understand what you say here i 23 that after this conference you went back and looked at a study! i 24 that had been completed before? 25 DR. RAO: Yes. i I Si 38*57 1 TETRACHLOROETHYLENE PAGE 196 2 DR. JONES: This one that's at twenty-four percei 3 DR. RAO: You see, the second arrow represents 4 June necropsy, June of 1982, which usually comes for reading 5 around October of 1982. And time of the conference. Right 6 after the conference all the incidences shifted. 7 DR. JONES: In connection with this twenty-four 8 percent under 1982------ 9 DR. RAO: Yes? 10 DR. JONES: ------you said that you looked at those 11 slides and they were all stage three? 12 DR. RAO: That's right. 13 DR. JONES: So that means that stage one and two 14 were not recognized? 15 DR. RAO: Weren1't called at the time. 16 DR. JONES: And that would explain-----17 DR. RAO: Stage one and two are present, but our 18 reading indicates we had actually--if we included stage two 19 and three, it would be more like sixty-six percent. 20 DR. JONES: Okay. 21 CHAIRMAN HOOK: Is there another hand over here? 22 (No response.) 23 CHAIRMAN HOOK: Thank you, Dr. Rao. 24 Back to our discussions on the study. Do we have 25 other comments? SL 038458 1 TETRACHLOROETHYLENE PAGE 197 2 CHEMICAL MANAGER: I would comment regarding the 3 actual staging of leukemias, I don't know whether Dr. Boorman 4 would care to make any comments about this now with respect 5 to what Dr. Rao said. 6 DR. BOORMAN: I think it's appropriate. You know, 7 I think it's been treated with a little bit more mystique than 8 it deserved. It was simply a matter of trying to look at 9 whether we were dealing with advanced stages or very early 10 cases or somewhere in between, so we simply broke it into 11 three stages. And I think it's added a lot of clarity to 12 know whether our calls and our judgments are being based on 13 early cases that are difficult to (tell from back count) or 14 whether they are such obvious cases that anybody would agree 15 that it's clearly an advanced case of mononuclear cell | 16 leukemia. 17 So that's simply what we've been doing. Once we 18 started doing it, there's more and more people interested 19 in it. I don't want to take too much time. j 20 There's sort of an implication that so little 21 is known about mononuclear cell leukemia that we should not 22 be staging it. That's simply not tne case. I think (Malone) 23 was one of the first ones to report the disease in 1970 in 24 the Fischer rat. And there's literally dozens of papers. 25 There's been real good work that's come out of Battelle- 03845g 1 TETRACHLOROETHYLENE PAGE 198 2 Columbus with Stromberg, for example. 3 We also had an in-house group here with Jeff 4 Branch, Mike (Peters), Bob (Marigold) (where we're maintaining 5 it transplantation). And we know how long it takes from the 6 time you inject the cell until they die and how long it takes 7 from the time you see cells in ( blood) until they 8 die and so forth. I think that's more detail than you want 9 it right now. But it's not as mysterious as you might be 10 led to believe. 11 I think in the interest of time I'll stop there. 12 CHAIRMAN HOOK: Fine. Thank you. Other comments 13 or discussion around the study? Dr. Purchase? 14 DR. PURCHASE: I have a couple of comments on 15 this. Firstly, I think the summary omits the dose levels that 16 were used in the long-term study. I may be wrong. I think 17 it actually misses them out. And I think that should be put 18 in there. 19 On page 56 there is a discussion of gliomas. And 20 again, I wonder whether this has taken into account whether 21 the glioma is fatal or not. Maybe a pathologist could help. 22 I think that they are usually non-fatal tumors. And there 23 fore, there is no significant increase if that is correct. 24 And the discussion in regard to the gliomas looks to me as 25 if it could be tightened up some. SL 038460 TETRACHLOROETHYLENE PAGE 199 And on page 83 there appears to be reference here and elsewhere in the report to kidney effects with both chlorinated alkanes and alkenes, some of which refer to Reports which are still under preparation within the NTP. Therefore, by definition, they are not available to the Peer Review Panel. And it would seem to me to be unwise to use that as a means of confirming a conclusion from this statement. It's not entirely clear which of those studies are in the pipeline and which are the ones that have already ben published. I'm sure that when those studies come out, they will refer to this one as supporting evidence. We can't have it both ways, particularly when they are not yet published. CHEMICAL MANAGER: With the exception of the study that I referred to of four strains of rats, they've all been peer-reviewed, and the four rat strain studies will be coming through, we. hope, in the next peer review. But we won't use that one as a reference here. DR. PURCHASE: The only other comment I have to make is that the leukemia incidence and the way in which it has been analyzed in this report, I would support Dr. | Swenberg's statement that one must recognize that the primary conclusions are drawn on the straight statistics and the staging is a secondary sort of elaboration of that. If SL 038461 TETRACHLOROETHYLENE PAGE 200 you look at it that way, I think that it will be unwise to move this one up to "clear evidence." I think it should remain "some." CHAIRMAN HOOK: Thank you. Other comments? Dr. Kociba? DR. KOCIBA: Is this going to be the standard approach that NTP uses in "staging" the mononuclear cell leukemias in all future reports being this is identified as a problem area? DR. BOORMAN: No. We're not routinely staging leukemias. If there is an increase in mononuclear cell leukemia and it becomes especially a question of whether it's related to mortality, then it's important to know whether or not there are advanced cases or not advanced cases. We recognize that it needs some additional work, and we're working on a publication right now that we will be submitting for peer review and getting input and stuff like that. So, this is just a crude step, but we hope to make it a little bit more elaborate. DR. KOCIBA: So is it your plan to delete it from this Report here until your work is done? DR. BOORMAN: No. I think there's nothing wrong-' I think the statistics and all the conclusions are based on the raw incidences, as Dr. Swenberg has said. All we've done SL 038462 * 1 TETRACHLOROETHYLENE PAGE 201 2 is we've also added for your information--these are the cases 3 where it's advanced, these are the cases where it's very early, 4 and these are the cases of stage two where it's in between. 5 And I think to delete that data would be 6 deleting useful data. We're not making our call on the 7 stages. 8 CHAIRMAN HOOK: Other comments? Dr. Hooper? 9 DR. HOOPER: Yeah. I wanted to comment on what 10 Dr. Mirer said. I think what I would encourage doing is 11 separating the characterizations of male and female rats. 12 And I would call the effect in males with mononuclear cell 13 leukemia as clear. If you look on page 52 at Table 12, the 14 statistics of using a life table test for the leukemia is IS significant trend, highly significant trend, and highly 16 significant high-dose, and a significant low-dose. 17 And also, as I think he commented on, the fact 18 that the high control incidence in a sense would mask or make 19 more difficult to (attach) to the fact in the low-dose and 20 high-dose groups. 21 The mention that the highest reported incidence 22 of leukemia in these animal:; is forty-six percent, and we're 23 considerably above that in the high-dose and the low-dose 24 groups. This finding in males is supported by the finding 25 in females, which is significant to the low-dose group. So, SL 038463 1 TETRACHLOROETHYLENE PAGE 202 2 in a sense, then, I think you have "clear evidence" because 3 you have the malignancy being clear in statistical effects, 4 and then support from the opposite sex. 5 In addition, I'm curious about the findings in 6 the brain tumors. On page 56, Table 15, we looked at gliomas, 7 and the controls were one of fifty in low-dose, zero o f fifty 8 and high-dose four of fifty in male rats. And here, at least 9 my understanding is that the historical control incidence, 10 the mean is 0.8 percent. 11 So you have a control incidence which obviously 12 is higher than historicals. Just one animal. But your high- 13 dose animals is quite higher than historical. And that's 14 not statistically significant, but in the past we've talked 15 about historical control incidences. And if we're going to 16 use them to diminish the significance of the tumor, I wonder 17 if you oughtn't to be flexible and in a -sense look at this 18 tumor of increased significance. Because you have some effect 19 that's much higher than historical control incidence. 20 So I would say that this tends again to augment 21 the fact that something is going on in males. I'd argue that 22 you have "clear" in males and "some" in females. 23 CHAIRMAN HOOK: Dr. Swenberg wanted to respond. 24 DR. SWENBERG: Yes. Let me address the brain 25 tumor issue before I go on to the point I was going to make. PENGAO C O .. 04 TONNE. N J. 0 7002 SL 038464 1 TETRACHLOROETHYLENE PAGE 203 2 For some reason in the last few years we're starting to see 3 a lot more brain tumors, and they seem to cluster. And the 4 statisticians don't have any idea why this is happening. But 5 I think--maybe Dick could comment on it, but you recently 6 had a study in Fischer rats where X think the control 7 incidence had fourteen percent or sixteen percent in the 8 controls. 9 And we've had the blue dye studies and this whole 10 food color series, and brain tumors have varied from one to 11 fourteen percent or zero to fourteen percent in the controls. 12 And therefore, I no longer accept that brain tumors are as 13 rare as we used to previously think they were. And we don 14 understand why they tend to cluster, but there sure as hell 15 is evidence that they are. 16 As to the males being "clear evidence," I'd like 17 to argue strongly against that. We've already heard that 18 the methylene chloride controls run in the same lab at 19 approximately the same time had sixty-eight percent mono 20 nuclear cell leukemias. So you're going to say sixty-eight, 21 seventy-four, seventy-four is a clear a clear effect of 22 carcinogenesis? I just can't buy that. It just doesn't make 23 good sense. 24 DR. RALL: It wasn't the experiment------ 25 DR. BOORMAN: This could be a relevant comment 038465 SL 1 TETRACHLOROETHYLENE PAGE 204 2 on the brain tumors. And this is something that Dr. Swenberg 3 just pointed out, but I would like to reiterate it. Dr. 4 (Solfeld) went back and looked at the aging study where we 5 had done several different studies at Hazelton, lifespan. 6 And he found in some groups zero brain tumors 7 and others I think it was four or five. But it was clear 8 there was statistically significant difference between some 9 control groups and the other control groups in brain tumors. 10 We pulled these brain tumors out and looked at 11 them. And they are not just a few clusters of gliol cells. 12 They are real tumors that are fairly large lesions. 13 Yet just for the exact reason that Swenberg stated, 14 we felt the best way to handle it was to put it out here in 15 the Report where everybody could see it, but we didn't call 16 it. 17 DR. HUFF: But those were lifespan studies and 18 to two years. 19 DR. BOORMAN; Yes. 20 CHAIRMAN HOOK: Dr. Kotelchuck and then Dr. 21 Kociba. 22 DR. KOTELCHUCK: In reference to what Dr. 23 Swenberg said, it is the concurrent controls that are the 24 ones that are the key and should be the main ones in making 25 the determination. They are fifty-six percent. It's not 0j8<66 1 TETRACHLOROETHYLENE PAGE 205 2 sixty-eight versus seventy-four. And I think that comes up 3 in a number of different cases. I think that the material 4 on page 52, in fact, argues for "clear," no't for "some." 5 CHAIRMAN HOOK: Or. Kociba and Dr. Perera. 6 DR. KOCIBA: Just one comment on the brain tumors. 7 I concur with what Dr. Boorman and Dr. Swenberg said about 8 the variability for whatever reason, we have on our own 9 observed these extreme variations in control groups. So I 10 really don't attach any significance to the observation of 11 brain tumors in this particular study. I wouldn't want to 12 see that be given more significance than what it really 13 indicates. 14 CHAIRMAN HOOK: Thank you. Dr. Perera? 15 DR. PERERA: Yes. I think Dr. Mirer's conclusions 16 about the mononuclear cell leukemias constituting "clear 17 evidence" are reasonable. But I also wonder why the increase 18 in the male rats of testicular interstitial cell lesions were 19 not included in our consideration that's found on page 57, 20 Table 16. And there is a positive trend by both tests and 21 a significant increase in both dose groups by the incidental 22 tumor tests. And I don't believe that's even mentioned in 23 the Abstract or the Conclusions. Why is that not also 24 factored into consideration of the positive evidence here? 25 CHAIRMAN HOOK: Dr. Mennear? SL 038467 i 1 TETRACHLOROETHYLENE PAGE 206 2 CHEMICAL MANAGER: This is a very common tumor, 3 of course, that develops in these animals. And although 4 it was statistically significant, usually wer find ninety-nine 5 to a hundred percent of the animals have the tumor. So 6 consequently based on our past experience, we're just not 7 enthusiastic about making that a--making a call on that tumor. 8 Dr. Swenberg had mentioned that, and the 9 statistics were--however, the life table analysis data were 10 correct. But the incidental tumor test, it comes down to 11 .05, but it's not a life-threatening tumor, so you don't want 12 to use it. You wouldn't use your life table analysis. 13 CHAIRMAN HOOK: I think it's time we brought this 14 thing to a close. 15 We are at a point now where some of you are going 16 with "some," and maybe some are going with "clear." But I'm 17 ready to accept a Motion to allow us to' vote. 18 DR. SWENBERG: All right. I move that we accept 19 the conclusion as written in the Draft Technical Report of 20 "some evidence" in the rats and "clear evidence" in mice. 21 CHAIRMAN HOOK: Thank you. Is there a second? 22 DR. HOOPER: Second. 23 CHAIRMAN HOOK: We have a second. 24 All right. We have a Motion on the floor that 25 we accept the Report. Are there substantive contributions SL 038468 1 TETRACHLOROETHYLENE PAGE 207 2 to this debate? Or should we bring it to a vote? 3 (No response.) 4 CHAIRMAN HOOK: Hearing none, I would bring it 5 to a vote. If you vote "Aye," then you're supporting "some 6 evidence" in rats based on the discussion we just had. If 7 you vote "Nay," we'll try again. 8 Those in favor of the Motion, which is to accept 9 the summary as written, indicate by raising your hand, please. 10 I see four positive votes. Those opposed? Five. And those 11 abstaining? Dr. Kociba and Dr. Purchase are abstaining. 12 Thank you. There seemed in my mind no real debate around 13 the mice. May I have a Motion about accepting the Report 14 for mice as "clear evidence" of carcinogenicity? 15 DR. HOOPER: So move. 16 DR. PERERA: Second. 17 CHAIRMAN HOOK: Moved and seconded. Those in 18 favor of accepting the Report regarding mice indicate by a 19 positive response. Nine. Abstentions? Dr. Purchase and 20 Dr. Kociba. Thank you. 21 Female rats, "some evidence" of carcinogenicity 22 in female rats. Do I have a Motion? 23 DR. HOOPER: So move. 24 CHAIRMAN HOOK: Second?- 25 DR. CROWLEY: Second. SL 038469  t 5 a" 1 TETRACHLOROETHYLENE PAGE 208 2 CHAIRMAN HOOK: Okay. We're voting for "some 3 evidence" of carcinogenicity in female rats. Those in favor, 4 please so indicate. Eight. Opposed? One. And two 5 abstentions. 6 Therefore, our alternative with male rats is some 7 one wants us to say "clear evidence." A Motion for "clear 8 evidence"? 9 DR. MIRER: So move. 10 CHAIRMAN HOOK: And a second? 11 DR. PERERA: Second. 12 CHAIRMAN HOOK: Okay. An "Aye" vote means you 13 will accept "clear evidence" of carcinogenicity in male rats. 14 Those in favor, indicate by raising your hand. Five. Opposed 7 I 15 Four. And our two abstentions. 16 Well, we didn't change a thing, we confirmed our 17 decision. Thank you. So, finally, we accepted everything 18 other than we strengthened the position in male rats and made 19 it "clear." Agree? Thank you very much. 20 (Spontaneous discussion.) 21 CHAIRMAN HOOK: Okay. Let's move on to the 22 next chemical, which is chlorendic acid. Dr. French, you I 23 did the study. 24 CHLORENDIC ACID 25 CHEMICAL MANAGER: Chlorendic acid is a chemical i ?0 1 CHLORENDIC ACID PAGE 209 2 intermediate used in the preparation of flame-retardant 3 polyester resins and plasticizers. In 1981, the manufacture 4 of chlorendic acid was estimated at approximately seften 5 tti i 1 1 i nw nmmHc e a K **** *3 6 pounds. 7 Chlorendic acid is manufactured in an essentially 8 closed system and as a chemical intermediate becomes an 9 integral component of the final product. This chemical was 10 nominated for studying after a class review of flame retar 11 dants because of its large production, structure-activity 12 considerations, and the potential for human exposure. 13 Presumably, the potential for human exposure is oral, 14 primarily through the environmental degradation of pesticides 15 and polyesters. 16 Toxicology and carcinogenesis studies were 17 conducted by administering chlorendic acid in feed to groups 18 of fifty male and fifty female F344/N rats and B6C3F1 mice 19 at concentrations of 0, 620, or 1,250 parts per million for 20 103 weeks. 21 These concentrations were selected because at 22 higher concentrations in the fourteen-day and thirteen-week j 23 studies in rats and mice, dosed groups had decreased mean 24 body weights, more deaths, and an increased incidence of liver 25 lesions. For example, centrilobular cytomegaly and mitotic SL 038471