- Email: [email protected]
Development and application of the bonchmark dose approach by the U.S. environmental protection agency
Book of Abstmcrs - EUROTOX ‘94
89
in this study, no mortalities, no neurological signs and no adverse effects on body weight and food consumption were noted. Histological examination of the spinal cord revealed a very minimal. focal or rnu~o~l superficial inflammation of the dun, mater, after 7 days of treatmen; and a slight to moderate inflarnrn~~~ of the dwa ma&r* limited to the external area, after 28 days of treatmeF.:!. No meningitis was obsewed. This method can be used for safety evaluation of drugs administered into the epidural space for period of up to 28 days without adverse damage related to the experimental procedures which could mask any potential krcel effects.
Bon0 Marrow Damage Attera-Exposureof &Ice to *“Am is CultureTiechnlques
R.L.Van Den Heuvel. G. Schoeters, H. Leppens. VI70, Belgium
Depattment of Environmen!, Boeretang 200, &2@g
~404
The present study shows that bone marrow cells can be considered as sensitive targets for chronic low level Oirradiation in mice at risk for bone tumour development. Bone marrow consists of a he~~en~s population of haemopoietic and stromal cells. Haamopoi~ic cells have a limited life span and are continuouslyproduced by proliferation and differentiation of haemopoietic stem cells. This process is controlled by the stromal microenvironment. Using in vitro assays, effects to the haemopoietic and stromal cells have been demonstrated after contamination of female mice with 241Americium at dose level which causes bone tumours in more than 50% of the animals (50 Bq 241Am/g mouse). The radiation induced changes were persistent up to 20 months after 241Am injection. Colony forming assays in v&o showed a decrease in the stromal stem cell {CFU-f) number as well as in the yield of granul~~~macrophage progenitors (CFU-GM). The regulatory role of the stroma in haemopoiesis was assessed by measuring the Cf U-GM production in long-term bone marrow cultures in which haemopoiesis is maintained in vitro. Results showed a decreased production of CFU-GM in cultures derived from exposed mice. This contirms previous data which showed an alteration in the supporting capacity of the stroma 17 weeks after 241Am injection. Key words: bone marrow toxicity; in vifro assays; a-irradiation
The SCIB-Mouseas a 7bolto Bridgethe Gap BetweanHumanand AnimalResponses H Van Loveren, C. De heer. National InstiMe for public Health and Environmental Rotection, Bilthoven, The Netherlands Se*ere combined immunodefi~ient @CID) mice lack functional 1 and B lymphocytes and are therefore incapable of rejecting xenografts. SCID mice have been used as recipients of human peripheral blood leukocytes. An other model pertained to the differentiation of human lymphoid cells from fetal origin. These models have been shown to be valuable for the study of human immune responses and lymphohemopoietic disorders. Attempts are now being made to use these model systems to study the toxicity of chemicals for the human immune system. Examples of such studies are the effects of 2.3.7.8 tetrachlorodibenzo-p-dioxin (tcdd), and tetrahydroxybutylimidizole. Whereas the former chemical exerted clear effects on the on human immune parameters in this model, tetrahydroxybutylimidizole failed to show this effect. Obviously a model system in which elements of the human immune system are transferred into SCID mice have certain restrictions. Yet. data yielded by such models will have implications for the process of human risk assessment. Key words: immunotoxicity;
SCID-mouse; extrapolation
DevelOpmffnland Applicationof the 5~~ehmarkDose Appmach by ths U.S. EnvIronmantal ProtectIonAgency J.J. Vandenberg. Health Effects Research Laboratory, US. Environmental Rotection Agency Environmental health-based regulatory decisions affect resource expenditures which can total many billions of dollars per year in the United States 11). Public policy related to environmental laws is based in part on evidence of a link between pollutant sources, human exposures and health elfects 121.The U.S. Environmental Protection Agency (EPA) uses risk assessment info~ation in determining exposure limits and to set regulatory and research priorities. The U.S. National Research Council (31recommended that EPA pursue development of alternatives to current practice in noncancer risk assessment and the Science Advisory Board to EPA has recommended evaluation of the Benchmark Dose (BMD) approach. EPA has committed to development and evaluation of this approach and, under the auspices of the EPA Risk Assessment Forum, is developing guidelines for BMD application by EPA regulatory programs. The development and application of the BMD approar,.h by EPA, opportunities for and impedimenta to BMD implementation, and research needs will be discussed.
Book ofA&macts - EUlWlVX ‘94
90
(11 U.S. Congress, Office of Technology Assessment, Researching Health Risks, OTA-BBS-570. Washington, UC (1993). 121 U.S. En~r~m~tal F%otectionAgency, The Role of Heafth Research in Support of EPA’s programs, EPOXY 90&34, Washington, DC (1990). [3] National Research Council, Science and Judgment in Risk rssessment (draft). Washington, DC (January 19. 1994). &y wo&:
Benchmark Doze method; non-cancer; risk assessment: dose-response modeling
Exam&&ton crfa Target organ Toxicitywith the Mu~f~ime~ional Qnrphicaland Ststistical
MspplngMethod M.Vama. K. Nagy. 2. Balogh. Institute forDrug
Research, Budapest Hungaty
Toxiceffects of a new. antiandrogenic test substance (developed in the Institute for Drug Research. Hungary)were studied on W&tar rats treated orally with 30.100 and 300 mg/kg doses within 28 days. Ketokonazol was used as a reference substance in 100 mg/kg dose. Results wili be discussed in details. Dose- and sexdependent alterations were observed by gross and histopathology in the liver of animals treated with the new substance and Ketokonazol. Several changes were registered in biochemical parameters and organ weights, too. This target organ toxicity will be shown by a new, multidimensional graphical and statistical mapping method. A number of biochemical parameters are now determined on the blood and urine. Such biochemical parameters are rarely independent of each other. Neith+rof our interest often focused on just one of the parameters. Rather,there are batter& of the parameters associated -with toxic actions at particular target organs. We propose to introduce the MGSM (Multidimensional Graphical ano Statistical Mapping) method to analyse these complex problems. The MGSM methsd includesthe graphical presentation of the data and a statistical pattern recognition procedue. The graphical presentation based on the below approximation: if an animal, from a group of N animals is charactensed by n measurements (measured parameters) and if the same measurements are made on all animals, the total amount of info,~~~at~on available may be represented as an n-side polygon. We shall call this polygon thepatrem po&gon. In our concept an individualpotygor?pattern belongs to a typical toxicological alteration on the target organ. We use the PRIMA (Pattern Recognition by Independent Multicategory Analysis) method for the statistical pattern recognition”The PRIMA classifier based on class distance can be applied in different complex cases. The conditions of applicability are less strict than those of other supervised pattern recognition methods. PRIMA can be applied successfully to incomplete data.
EstrogenfcEffectsof SomeXenobiotics M. Vamova, M. Gajdod. J. Jakubovsky,L. Wsolov& lnstifute of Reventiveand Cliniicelmeclicine, BretMave, Slovak RepI/blic;~pe~mentaf evidence revealsthat some environmentalcom~unds affect estrogen production and their meta~~m and thus they function as xenoestrogens. Exposure to exogenous estrogens is known to have deleterious effects on the reproductive potential. Many of these xenoestrogenic compounds also experimentally induce mammary carcinogenesis. In our study, neonatal rats were injected ip on days 4-7 after birth with Tween 80 and Polyethyleneglycol3(;iir.For prediction of estrogenicity of chemicals the time of vaginal opening in neonatal rats and uterine epithelial cellular hyperthrophy,the estrus cycle and histopathoiogy of the uterus, ovaries, adrenal glands and pituitary glands were evaluated. Treatment of rats by both compounds accelerated maturation, caused uterine epithelial cellular hyperthrophy, prolonged the estrus cycle and induced persistent vaginal estrus. Squamous cell metaplasia of the epithelial lining of the uterus and cytologicalchanges in the uterus were indicative of chronic estrogenic stimulation. Key words: estrogenicity; Tween 80: Polyethyleneglycol300; neonatal rats
Cross-Reecthdtlesof HumanCytokineAssey Kits in VariousLaboratoryAnimal Species F.Verdier, M. Aujoulat, F.Cor.$evaux,J. Descotes. Pharmakon Eumpe. 99593 Mrbresle, France; leboratoire d’lmmunotoxicologie, INSERT U&l, Lyon fmnc~ Cytokine assays are useful to investigate the interactions of pharmaceuticals, and particularly new biotechnology products. on the immune system as part of their ~rec~inica~sa!ety assessment. As no specific reagents 8re avail-
89
in this study, no mortalities, no neurological signs and no adverse effects on body weight and food consumption were noted. Histological examination of the spinal cord revealed a very minimal. focal or rnu~o~l superficial inflammation of the dun, mater, after 7 days of treatmen; and a slight to moderate inflarnrn~~~ of the dwa ma&r* limited to the external area, after 28 days of treatmeF.:!. No meningitis was obsewed. This method can be used for safety evaluation of drugs administered into the epidural space for period of up to 28 days without adverse damage related to the experimental procedures which could mask any potential krcel effects.
Bon0 Marrow Damage Attera-Exposureof &Ice to *“Am is CultureTiechnlques
R.L.Van Den Heuvel. G. Schoeters, H. Leppens. VI70, Belgium
Depattment of Environmen!, Boeretang 200, &2@g
~404
The present study shows that bone marrow cells can be considered as sensitive targets for chronic low level Oirradiation in mice at risk for bone tumour development. Bone marrow consists of a he~~en~s population of haemopoietic and stromal cells. Haamopoi~ic cells have a limited life span and are continuouslyproduced by proliferation and differentiation of haemopoietic stem cells. This process is controlled by the stromal microenvironment. Using in vitro assays, effects to the haemopoietic and stromal cells have been demonstrated after contamination of female mice with 241Americium at dose level which causes bone tumours in more than 50% of the animals (50 Bq 241Am/g mouse). The radiation induced changes were persistent up to 20 months after 241Am injection. Colony forming assays in v&o showed a decrease in the stromal stem cell {CFU-f) number as well as in the yield of granul~~~macrophage progenitors (CFU-GM). The regulatory role of the stroma in haemopoiesis was assessed by measuring the Cf U-GM production in long-term bone marrow cultures in which haemopoiesis is maintained in vitro. Results showed a decreased production of CFU-GM in cultures derived from exposed mice. This contirms previous data which showed an alteration in the supporting capacity of the stroma 17 weeks after 241Am injection. Key words: bone marrow toxicity; in vifro assays; a-irradiation
The SCIB-Mouseas a 7bolto Bridgethe Gap BetweanHumanand AnimalResponses H Van Loveren, C. De heer. National InstiMe for public Health and Environmental Rotection, Bilthoven, The Netherlands Se*ere combined immunodefi~ient @CID) mice lack functional 1 and B lymphocytes and are therefore incapable of rejecting xenografts. SCID mice have been used as recipients of human peripheral blood leukocytes. An other model pertained to the differentiation of human lymphoid cells from fetal origin. These models have been shown to be valuable for the study of human immune responses and lymphohemopoietic disorders. Attempts are now being made to use these model systems to study the toxicity of chemicals for the human immune system. Examples of such studies are the effects of 2.3.7.8 tetrachlorodibenzo-p-dioxin (tcdd), and tetrahydroxybutylimidizole. Whereas the former chemical exerted clear effects on the on human immune parameters in this model, tetrahydroxybutylimidizole failed to show this effect. Obviously a model system in which elements of the human immune system are transferred into SCID mice have certain restrictions. Yet. data yielded by such models will have implications for the process of human risk assessment. Key words: immunotoxicity;
SCID-mouse; extrapolation
DevelOpmffnland Applicationof the 5~~ehmarkDose Appmach by ths U.S. EnvIronmantal ProtectIonAgency J.J. Vandenberg. Health Effects Research Laboratory, US. Environmental Rotection Agency Environmental health-based regulatory decisions affect resource expenditures which can total many billions of dollars per year in the United States 11). Public policy related to environmental laws is based in part on evidence of a link between pollutant sources, human exposures and health elfects 121.The U.S. Environmental Protection Agency (EPA) uses risk assessment info~ation in determining exposure limits and to set regulatory and research priorities. The U.S. National Research Council (31recommended that EPA pursue development of alternatives to current practice in noncancer risk assessment and the Science Advisory Board to EPA has recommended evaluation of the Benchmark Dose (BMD) approach. EPA has committed to development and evaluation of this approach and, under the auspices of the EPA Risk Assessment Forum, is developing guidelines for BMD application by EPA regulatory programs. The development and application of the BMD approar,.h by EPA, opportunities for and impedimenta to BMD implementation, and research needs will be discussed.
Book ofA&macts - EUlWlVX ‘94
90
(11 U.S. Congress, Office of Technology Assessment, Researching Health Risks, OTA-BBS-570. Washington, UC (1993). 121 U.S. En~r~m~tal F%otectionAgency, The Role of Heafth Research in Support of EPA’s programs, EPOXY 90&34, Washington, DC (1990). [3] National Research Council, Science and Judgment in Risk rssessment (draft). Washington, DC (January 19. 1994). &y wo&:
Benchmark Doze method; non-cancer; risk assessment: dose-response modeling
Exam&&ton crfa Target organ Toxicitywith the Mu~f~ime~ional Qnrphicaland Ststistical
MspplngMethod M.Vama. K. Nagy. 2. Balogh. Institute forDrug
Research, Budapest Hungaty
Toxiceffects of a new. antiandrogenic test substance (developed in the Institute for Drug Research. Hungary)were studied on W&tar rats treated orally with 30.100 and 300 mg/kg doses within 28 days. Ketokonazol was used as a reference substance in 100 mg/kg dose. Results wili be discussed in details. Dose- and sexdependent alterations were observed by gross and histopathology in the liver of animals treated with the new substance and Ketokonazol. Several changes were registered in biochemical parameters and organ weights, too. This target organ toxicity will be shown by a new, multidimensional graphical and statistical mapping method. A number of biochemical parameters are now determined on the blood and urine. Such biochemical parameters are rarely independent of each other. Neith+rof our interest often focused on just one of the parameters. Rather,there are batter& of the parameters associated -with toxic actions at particular target organs. We propose to introduce the MGSM (Multidimensional Graphical ano Statistical Mapping) method to analyse these complex problems. The MGSM methsd includesthe graphical presentation of the data and a statistical pattern recognition procedue. The graphical presentation based on the below approximation: if an animal, from a group of N animals is charactensed by n measurements (measured parameters) and if the same measurements are made on all animals, the total amount of info,~~~at~on available may be represented as an n-side polygon. We shall call this polygon thepatrem po&gon. In our concept an individualpotygor?pattern belongs to a typical toxicological alteration on the target organ. We use the PRIMA (Pattern Recognition by Independent Multicategory Analysis) method for the statistical pattern recognition”The PRIMA classifier based on class distance can be applied in different complex cases. The conditions of applicability are less strict than those of other supervised pattern recognition methods. PRIMA can be applied successfully to incomplete data.
EstrogenfcEffectsof SomeXenobiotics M. Vamova, M. Gajdod. J. Jakubovsky,L. Wsolov& lnstifute of Reventiveand Cliniicelmeclicine, BretMave, Slovak RepI/blic;~pe~mentaf evidence revealsthat some environmentalcom~unds affect estrogen production and their meta~~m and thus they function as xenoestrogens. Exposure to exogenous estrogens is known to have deleterious effects on the reproductive potential. Many of these xenoestrogenic compounds also experimentally induce mammary carcinogenesis. In our study, neonatal rats were injected ip on days 4-7 after birth with Tween 80 and Polyethyleneglycol3(;iir.For prediction of estrogenicity of chemicals the time of vaginal opening in neonatal rats and uterine epithelial cellular hyperthrophy,the estrus cycle and histopathoiogy of the uterus, ovaries, adrenal glands and pituitary glands were evaluated. Treatment of rats by both compounds accelerated maturation, caused uterine epithelial cellular hyperthrophy, prolonged the estrus cycle and induced persistent vaginal estrus. Squamous cell metaplasia of the epithelial lining of the uterus and cytologicalchanges in the uterus were indicative of chronic estrogenic stimulation. Key words: estrogenicity; Tween 80: Polyethyleneglycol300; neonatal rats
Cross-Reecthdtlesof HumanCytokineAssey Kits in VariousLaboratoryAnimal Species F.Verdier, M. Aujoulat, F.Cor.$evaux,J. Descotes. Pharmakon Eumpe. 99593 Mrbresle, France; leboratoire d’lmmunotoxicologie, INSERT U&l, Lyon fmnc~ Cytokine assays are useful to investigate the interactions of pharmaceuticals, and particularly new biotechnology products. on the immune system as part of their ~rec~inica~sa!ety assessment. As no specific reagents 8re avail-