TOXICOLOGY STUDIES OF - National Toxicology Program
NATIONAL TOXICOLOGY PROGRAMTechnical Report Series&/No. 361{*, W''.,.* J * . , ,TOXICOLOGY AND CARCINOGENESISSTUDIES OFHEXACHLOROETHANE(CAS NO. 67-72-1)IN F344/N RATS(GAVAGE STUDIES)U.S. DEPARTMENT O F HEALTH AND H U M A N SERVICESPublic Health ServiceNational Institutes of Health
NTP TECHNICAL REPORTON THETOXICOLOGY AND CARCINOGENESISSTUDIES OF HEXACHLOROETHANE(CAS NO. 67-72-1)IN F344/N RATS(GAVAGE STUDIES)William C. Eastin, Jr., Ph.D., Study ScientistNATIONAL TOXICOLOGY PROGRAMP.O. Box 12233Research Triangle Park, NC 27709August 1989NTP TR 361NIH Publication No. 89-2816U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICESPublic Health ServiceNational Institutes of Health
CONTENTSPAGEABSTRACT3EXPLANATION OF LEVELS OF EVIDENCE OF CARCINOGENIC ACTIVITY6CONTRIBUTORS7PEER REVIEW PANEL8SUMMARY OF PEER REVIEW COMMENTS9I.II.III.IV.V.INTRODUCTION11MATERIALS AND METHODS17RESULTS29RATS30GENETIC TOXICOLOGY40DISCUSSION AND CONCLUSIONS45REFERENCES51APPENDIXESAPPENDIX AAPPENDIX BSUMMARY OF LESIONS IN MALE RATS IN THE TWO-YEAR GAVAGE STUDYOF HEXACHLOROETHANE61SUMMARY OF LESIONS IN FEMALE RATS IN THE TWO-YEAR GAVAGE STUDYOF HEXACHLOROETHANE89APPENDIX CSENTINEL ANIMAL PROGRAM113APPENDIX DINGREDIENTS, NUTRIENT COMPOSITION, AND CONTAMINANT LEVELS INNIH 07 RAT AND MOUSE RATION115AUDIT SUMMARY119APPENDIX EHexachloroethane, NTP TR 361
ClClI II ICl ClCl-c-c-ClHEXACHLOROETHANECAS NO.67-72-1Molecular weight 236.7c2c16Synonyms: carbon hexachloride; ethane hexachloride; hexachlorethane; rchloroethaneTrade names: Avlothane; Distokal; Distopan; Distopin; Egitol; Falkitol; Fasciolin; Mottenhexe;PhenohepABSTRACTHexachloroethane is used in organic synthesis a s a retarding agent in fermentation, as a camphorsubstitute in nitrocellulose, in pyrotechnics and smoke devices, in explosives, and as a solvent. Inprevious long-term gavage studies with B6C3F1 mice and Osborne-Mendel rats (78 weeks of exposurefollowed by 12-34 weeks of observation), hexachloroethane caused increased incidences of hepatocellular carcinomas in mice (NC1 TR 68). However, survival of low and high dose rats was reduced compared with that of vehicle controls, and the effects on rats were inconclusive. Therefore, additionaltoxicology and carcinogenesis studies were conducted in F344/N rats by administering hexachloroethane (approximately 99% pure) in corn oil by gavage to groups of males and females for 16 days, 13weeks, or 2 years. Genetic toxicology studies were conducted in Salmonella typhimurium and in Chinese hamster ovary (CHO) cells. Urinalysis was performed in conjunction with the 13-week studies.Sixteen-Day Studies: In the 16-day studies (dose range, 187-3,000 mg/kg), all rats that received 1,500or 3,000 mg/kg and 1/5 males and 215 females that received 750 mg/kg died before the end of the studies. Final mean body weights of rats that received 750 mg/kg were 25% lower than that of vehiclecontrols for males and 37% lower for females. Compound-related clinical signs seen at 750 mg/kg ormore included dyspnea, ataxia, prostration, and excessive lacrimation. Other compound-related effects included hyaline droplet formation in the tubular epithelial cells in all dosed males and tubularcell regeneration and granular casts in the tubules a t the corticomedullary junction in the kidney inmales receiving 187 and 375 mg/kg.Thirteen-Week Studies: In the 13-week studies (dose range, 47-750 mg/kg), 5/10 male rats and 2/10female rats that received 750 mg/kg died before the end of the studies. The final mean body weight ofmale rats that received 750 mg/kg was 19% lower than that of vehicle controls. Compound-relatedclinical signs for both sexes included hyperactivity a t doses of 94 mg/kg or higher and convulsions atdoses of 375 or 750 mg/kg. The relative weights of liver, heart, and kidney were increased for exposedmales and females. Kidney lesions were seen in all dosed male groups, and the severity increasedwith dose. Papillary necrosis and tubular cell necrosis and degeneration in the kidney and hemorrhagic necrosis in the urinary bladder were observed in the five male rats that received 750 mg/kgand died before the end of the studies; a t all lower doses, hyaline droplets, tubular regeneration, andgranular casts were present in the kidney. No chemical-related kidney lesions were observed in females. Foci of hepatocellular necrosis were observed in several male and female rats a t doses of 188mg/kg or higher.3Hexachloroethane, NTP TR 361
Dose selection for the 2-year studies was based primarily on the lesions of the kidney in males and ofthe liver in females. Studies were conducted by administering hexachloroethane in corn oil by gavage at 0, 10, or 20 mg/kg body weight, 5 days per week, to groups of 50 male rats. Groups of 50 female rats were administered 0,80,or 160 mg/kg on the same schedule.Body Weight and Survival in the Two-year Studies: Mean body weights of high dose rats wereslightly (5%-9%)lower than those of vehicle controls toward the end of the studies. No significant differences in survival were observed between any groups of rats (male: vehicle control, 31/50; 10mg/kg, 29/50; 20 mg/kg, 26/50; female: vehicle control, 32/50; 80 mg/kg, 27/50; 160 mg/kg, 32/50).Nonneoplastic and Neoplastic Effects in the Two-year Studies: Incidences of kidney mineralization(vehicle control, 2/50; low dose, 15/50; high dose, 32/50) and hyperplasia of the pelvic transitional epithelium (0150; 7/50; 7/50) were increased in dosed male rats. Renal tubule hyperplasia was observedat an increased incidence in high dose male rats (260; 4/50; 11/50). These lesions have been describedas characteristic of the hyaline droplet nephropathy that is associated with an accumulation of livergenerated aap-globulin in the cytoplasm of tubular epithelial cells. The severity of nephropathy wasincreased in high dose male rats (moderate vs. mild), and the incidences and severity of nephropathywere increased in dosed females (22150; 42/50; 45/50). The incidences of adenomas (1150; 2/50; 4/50),carcinomas (0150; 0150; 3/50), and adenomas or carcinomas (combined) (1150; 2/50; 7/50) of the renaltubule were also increased in the high dose male group. One of the carcinomas in the high dose groupmetastasized to the lung. No compound-related neoplasms were observed in females.The incidence of pheochromocytomas of the adrenal gland in low dose male rats was significantlygreater than that in vehicle controls (15150; 28/45; 21/49), and the incidences for both dosed groupswere greater than the mean historical control incidence (28% f 11%).Genetic Toxicology: Hexachloroethane was not mutagenic in S . typhimurium strains TA98, TA100,TA1535, or TA1537 when tested with and without exogenous metabolic activation. In CHO cells,hexachloroethane did not induce chromosomal aberrations with or without metabolic activation butdid produce sister chromatid exchanges in the presence of exogenous metabolic activation.Audit: The data, documents, and pathology materials from the 2-year studies of hexachloroethanehave been audited. The audit findings show that the conduct of the studies is documented adequatelyand support the data and results given in this Technical Report.Conclusions: Under the conditions of these 2-year gavage studies, there was clear evidence of carcinogenic activity* of hexachloroethane for male F344/N rats, based on the increased incidences of renalneoplasms. The marginally increased incidences of pheochromocytomas of the adrenal gland mayhave been related to hexachloroethane administration to male rats. There was no evidence of carcinogenic activity of hexachloroethane for female F344/N rats administered 80 or 160 mg/kg by gavage for103 weeks.The severity of nephropathy and incidences of linear mineralization of the renal papillae and hyperplasia of the transitional epithelium of the renal pelvis were increased in dosed male rats. The incidences and severity of nephropathy were increased in dosed female rats.*Explanation of Levels of Evidence of Carcinogenic Activity is on page 6.A summary of the Peer Review comments and the public discussion on this Technical Report appears on page 9.Hexachloroethane, NTP TR 3614
SUMMARY OF THE TWO-YEAR GAVAGE AND GENETIC TOXICOLOGY STUDIES OFHEXACHLOROETHANEMale F344/N RatsFemale F344/N RatsDoses0,10, or 20 mg/kg hexachloroethane in corn oil, 5 d/wk0,80, or 160 mg/kg hexachloroethane in corn oil, 5 d/wkBody weights in the 2-year studyHigh dose slightly less than vehiclecontrolsHigh dose slightly less than vehicle controlsSurvival rates in the 2-year study31/50; 29/50; 26/5032/50; 27/50; 32/50Nonneoplastic effectsKidney mineralization, hyperplasia of the pelvis, tubulehyperplasia; increased severity of nephropathy at the high doseIncreased incidenceand severity of nephropathyNeoplastic effectsRenal neoplasms(1/50; 2/50; 7/50)NoneLevel of evidence of carcinogenic activityClear evidenceNo evidenceOther considerationsAdrenal gland pheochromocytomas(15/50; 28/45; 21/49)Genetic toxicologySalmonella(gene mutation)Negative with andwithout S9CHO Cells in VitroAberrationNegative without S9;Negative with andpositive with S9without S9SCEHexachloroethane, NTP TR 361
EXPLANATION OF LEVELS OF EVIDENCE OF CARCINOGENIC ACTIVITYThe National Toxicology Program describes the results of individual experiments on a chemical agent and notes the strength ofthe evidence for conclusions regarding each study. Negative results, in which the study animals do not have a greater incidenceof neoplasia than control animals, do not necessarily mean that a chemical is not a carcinogen, inasmuch as the experiments areconducted under a limited set of conditions. Positive results demonstrate that a chemical is carcinogenic for laboratory animalsunder t&e conditions of the study and indicate that exposure to the chemical has the potential for hazard to humans. Otherorganizations, such as the International Agency for Research on Cancer, assign a strength of evidence for conclusions based onan examination of all available evidence including: animal studies such as those conducted by the NTP, epidemiologic studies,and estimates of exposure. Thus, the actual determination of risk to humans from chemicals found to be carcinogenic in laboratory animals requires a wider analysis that extends beyond the purview ofthese studies.Five categories of evidence of carcinogenic activity are used in the Technical Report series to summarize the strength ofthe evidence observed in each experiment: two categories for positive results ("Clear Evidence" and "Some Evidence"); one categoryfor uncertain findings ("Equivocal Evidence"); one category for no observable effects ("No Evidence"); and one category for experiments that because ofmajor flaws cannot be evaluated ("Inadequate Study"). These categories of interpretative conclusionswere first adopted in June 1983 and then revised in March 1986 for use in the Technical Reports series to incorporate morespecifically the concept of actual weight of evidence of carcinogenic activity. For each separate experiment (male rats, femalerata, male mice, female mice), one of the following quintet is selected to describe the findings. These categories refer to thestrength of the experimental evidence and not to either potency or mechanism.Clear Evidence of Carcinogenic Activity is demonstrated by studies that are interpreted as showing a dose-related(i)increase of malignant neoplasms, (ii) increase of a combination of malignant and benign neoplasms, or (iii) markedincrease of benign neoplasms if there is an indication from this or other studies of the ability of such tumors to progressto malignancy.0Some Evidence of Carcinogenic Activity is demonstrated by studies that are interpreted as showing a chemicallyrelated increased incidence of neoplasms (malignant, benign, or combined) in which the strength of the response is lessthan that required for clear evidence.Equivocal Evidence of Carcinogenic Activity is demonstrated by studies that are interpreted as showing a marginal increase of neoplasms that may be chemically related.0No Evidence of Carcinogenic Activity is demonstrated by studies that are interpreted as showing no chemically related increases in malignant or benign neoplasms.Inadequate Study of Carcinogenic Activity is demonstrated by studies that because of major qualitative or quantitative limitations cannot be interpreted a s valid for showing either the presence or absence of carcinogenic activity.W h e n aconclusion statement for a particular experiment is selected, consideration must be given to key factors that would extend the actual boundary of an individual category of evidence. This should allow for incorporation of scientific experience andcurrent understanding of long-term carcinogenesis studies in laboratory animals, especially for those evaluations that may beon the borderline between two adjacent levels. These considerations should include:000000The adequacy of the experimental design and conduct;Occurrence of common versus uncommon neoplasia;Progression(or lack thereon from benign to malignant neoplasia as well as from preneoplastic to neoplastic lesions;Some benign neoplasms have the capacity to regress but others (of the same morphologic type) progress. At present, itis impossible to identify the difference. Therefore, where progression is known to be a possibility, the most prudentcourse is to assume that benign neoplasms of those types have the potential to become malignant;Combining benign and malignant tumor incidences known or thought to represent stages of progression in the same organ or tissue;Latency in tumor induction;Multiplicity in site-specific neoplasia;Metastases;Supporting information from proliferative lesions (hyperplasia) in the same site of neoplasia or in other experiments(same lesion in another sex or species);The presence or absence ofdose relationships;The statistical significance of the observed tumor increase;The concurrent control tumor incidence as well as the historical control rate and variability for a specific neoplasm;Survival-adjustedanalyses and false positive or false negative concerns;Structure-activity correlations; andIn some cases, genetic toxicology.Hexachloroethane, NTP TR 3616
CONTRIBUTORSThe NTP Technical Report on the Toxicology and Carcinogenesis Studies of Hexachloroethane isbased on 13-week studies that began in April 1981 and ended in July 1981 and on 2-year studies thatbegan in April 1982 and ended in April 1984 at EG&G Mason Research Institute (Worcester, MA).National Toxicology Program(Evaluated Experiment, Interpreted Results, and Reported Findings)William C. Eastin, Jr., Ph.D., Study ScientistJohn Bucher, Ph.D.Scot L. Eustis, D.V.M., Ph.D.Joseph K. Haseman,Ph.D.James Huff, Ph.D.(Discipline Leaders and Principal Contributors)Jack Bishop,Ph.D.Douglas W. Bristol, Ph.D.R. Chhabra, Ph.D.C.W. Jameson, Ph.D.E.E. McConnell, D.V.M.G.N.Rao, D.V.M., Ph.D.B.A.Schwetz, D.V.M., Ph.D.M. Vernon, Ph.D.DouglasWalters,Ph.D.NTP Pathology Working Group(Evaluated Slides and Prepared Pathology Report on 6/2/87)Paul Hildebrandt, D.V.M. (Chair) (PATHCO, Inc.) SuzanneNeuenschwander, D.V.M.Scot L. Eustis, D.V.M., Ph.D. (NTP)ExperimentalPathology Laboratories, Inc.Katherina Heider(D.V.M.) (CIBA-Geigy Limited) James A. Popp, D.V.M., Ph.D. (ChemicalRobert Hrubt, D.V.M. (Austrian ResearchIndustryInstitute ofToxicology)Center, Seibersdorf)AgnesB. Russfield, M.D., Ph.D.(EG&G MasonJoel Leininger, D.V.M., Ph.D. (University ofResearch Institute)Minnesota)Principal Contributors at EG&G Mason Research Institute(Conducted Studies and Evaluated Tissues)Herman S. Lilja, Ph.D.Miasnig Hagopian, Ph.D.AgnesB. Russfield, M.D.,Ph.D.Principal Contributors at Experimental Pathology Laboratories, Inc.(Provided Pathology Quality Assurance)J. GauchatSuzanneNeuenschwander, D.V.M.Principal Contributors at Carltech Associates, Inc.(Contractor for Technical Report Preparation)William D.Theriault, Ph.D.Abigail C. Jacobs, Ph.D.John Warner, M.S.Naomi Levy,B.A.Hexachloroethane, NTP TR 361
PEER REVIEW PANELThe members of the Peer Review Panel who evaluated the draft Technical Report on hexachloroethane on October 3, 1988, are listed below. Panel members serve as independent scientists, not asrepresentatives of any institution, company, or governmental agency. In this capacity, Panel members have five major responsibilities: (a) to ascertain that all relevant literature data have been adequately cited and interpreted, (b) to determine if the design and conditions of the NTP studies wereappropriate, (c) to ensure that the Technical Report presents the experimental results and conclusions fully and clearly, (d) to judge the significance of the experimental results by scientific criteria,and (e) to assess the evaluation of the evidence of carcinogenicity and other observed toxic responses.National Toxicology Program Board of Scientific CounselorsTechnical Reports Review SubcommitteeRobert A. Scala, Ph.D.* (Chair)Senior Scientific Advisor, Medicine and Environmental Health DepartmentResearch and Environmental Health Division, Exxon CorporationEast Millstone, NJMichael A. Gallo, Ph.D.Associate Professor, Director of ToxicologyDepartment of Environmental and CommunityMedicine, UMDNJ - Robert Wood JohnsonMedical School, Piscataway, NJFrederica Perera, Dr. P.H. (Acting Chair)Division of Environmental SciencesSchool of Public HealthColumbia UniversityNew York, NYAd Hoc Subcommittee Panel of ExpertsJohn Ashby, Ph.D.William Lijinsky, Ph.D.*Imperial Chemical Industries, PLCDirector, Chemical CarcinogenesisFrederick Cancer Research FacilityCentral Toxicology LaboratoryFrederick, MDAlderley Park, EnglandBarbara McKnight, Ph.D. (PrincipalReviewer) Assistant ProfessorDepartment of BiostatisticsUniversity of Washington, Seattle, WARobert H. Garman, D.V.M.Bushy Run LaboratoriesExport, PAConsultants in Veterinary PathologyMurrysville, PAFranklin E. Mirer, Ph.D. (Principal Reviewer)Director, Health and Safety DepartmentInternational Union, United AutoWorkers, Detroit, MILois Swirsky Gold, Ph.D.University of CaliforniaLawrence Berkeley LaboratoryBerkeley, CAPaul M. Newberne, D.V.M., Ph.D.Professor, Mallory Institute of PathologyBoston, MACurtis D. Klaassen, Ph.D.Professor, Department of Pharmacology andToxicologyUniversity of Kansas Medical CenterKansas City, KSJames A. Popp, D.V.M., Ph.D. (PrincipalReviewer) Head, Department ofExperimental Pathology and ToxicologyChemical Industry Institute of ToxicologyResearch Triangle Park, NC*Unable to attendHexachloroethane, NTP TR 3618
SUMMARY OF PEER REVIEW COMMENTSON THE TOXICOLOGY AND CARCINOGENESIS STUDIES OFHEXACHLOROETHANEOn October 3,1988, the draft Technical Report on the toxicology and carcinogenesis studies of hexachloroethane received public review by the National Toxicology Program Board of Scientific Counselors’ Technical Reports Review Subcommittee and associated Panel of Experts. The review meetingwas held a t the National Institute of Environmental Health Sciences, Research Triangle Park, NC.Dr. W.C. Eastin, NIEHS, began the discussion by reviewing the experimental design, results, andproposed conclusions (clear evidence of carcinogenic activity for male rats, no evidence of carcinogenicactivity for female rats).Dr. Popp, a principal reviewer, agreed with the conclusion for female rats but thought that the conclusion for male rats should be reduced to some evidence of carcinogenic activity, based on the incidencesof renal neoplasms (one in the vehicle controls vs. two in the low dose group and seven in the highdose group) and on hyaline droplet nephropathy and its likely relationship to the renal tubular cellneoplasms. In his opinion, the high dose for male rats was too low, being below the lowest dose evaluated in the 13-week study. Dr. Eastin replied that the choice of the high dose for male rats reflectedthe fact that there was toxicity even a t the lowest dose
toxicology and carcinogenesis studies were conducted in F344/N rats by administering hexachloro- ethane (approximately 99%pure) in corn oil by gavage to groups of males and females for 16 days, 13 weeks, or 2 years. Genetic toxicology studies were conducted in Salmonella typhimurium and in Chi- nese hamster ovary (CHO) cells.
toxicology data would potentially be required. For example, as noted in the toxicology data requirements table, swimming pool, wood preservative, metalworking fluid, and aquatic areas uses require toxicology data in addition to the core toxicology data. Again, the use pattern and specific use site(s) should be examined to determine the data .
A Small Dose of Toxicology A book chapter of A Small Dose of Toxicology - The Health Effects of Common Chemicals By Steven G. Gilbert, PhD, DABT Institute of Neurotoxicology & Neurological Disorders (INND) Seattle, WA 98115 E-mail: sgilbert@innd.org Supporting web sites web: www.asmalldoseof.org - "A Small Dose of Toxicology"
forensic toxicology). SWGTOX will also establish a uniform Code of Ethics for forensic toxicologists, identify areas of research and development in the field of forensic toxicology, and promote public awareness of the field of forensic toxicology through outreach. What professional groups
4 Toxicology Toxicology Terminology Toxicology is the study of the adverse effects of chemicals or physical agents on living organisms. A toxicologist is a scientist that determines the harmful effects of agents and the cellular, biochemical, and molecular mechanisms responsible for the effects. Toxicant, toxin, and poison are often used interchangeably in the literature; however,
The classic connotation of toxicology was "the science of poisons." Since that time, the science has expanded to encompass several disciplines. Toxicology is the study of the interaction between chemical agents and biological systems. While the subject of toxicology is quite complex, it is necessary to understand the basic concepts in order to make
220-D200 Toxicology Training Manual Qualtrax ID: 2852 Issued by Toxicology Program Manager Qualtrax Revision 3 Issue Date: 14-August-2018 Page 6 of 63 1.3 Training Period The length of the training period is a highly variable matter and will be left to the determination of the Toxicology Program Manager.
Toxicology Tutors (Tox Tutors) In the Tox Tutors , created by the US Health and Human Services, you can learn about the history and explore an introduction to the basic principles of toxicology in the module entitled Introduction to Toxicology and Dose-Response.
Artificial intelligence: opportunities and implications for the future of decision making. 9 November 2016. Big data, artificial intelligence, machine learning and data protection 20170904 Version: 2.2 7 This may not sound very different from standard methods of data analysis. But the difference is that AI programs don’t linearly analyse data in the way they were originally programmed .
