ILSI Risk Science Institute Acrylamide Toxicity: Research to Address Key Data Gaps Presented by Dr. Stephen S. Olin ILSI Risk Science Institute

JIFSAN/NCFST Workshop on Acrylamide in Food October 28-30, 2002 – Chicago October 28-30, 2002 – Chicago Mechanisms of Formation of Acrylamide in Food Mechanisms of Formation of Acrylamide in Food Analytical Methods Analytical Methods Exposure and Biomarkers Exposure and Biomarkers Toxicology and Metabolic Consequences Toxicology and Metabolic Consequences Risk Communication Risk Communication

ILSI Risk Science Institute Toxicity Focus Areas Kinetics and Metabolism Kinetics and Metabolism Genetic Toxicity Genetic Toxicity Reproductive and Developmental Toxicity Reproductive and Developmental Toxicity Carcinogenicity Carcinogenicity Neurotoxicity Neurotoxicity Epidemiology Epidemiology

ILSI Risk Science Institute Acrylamide Toxicology Research Themes Assess the significance of adverse effects observed at high doses for low-level human exposures in foods Assess the significance of adverse effects observed at high doses for low-level human exposures in foods Assess the significance for humans of effects observed in vitro or in vivo in rodents Assess the significance for humans of effects observed in vitro or in vivo in rodents

ILSI Risk Science Institute Kinetics, Metabolism & Modes of Action: Research Needs Critical events and dose metrics related to modes of action (MoA) for key acrylamide toxicities Critical events and dose metrics related to modes of action (MoA) for key acrylamide toxicities Metabolic fate and kinetics in humans Metabolic fate and kinetics in humans Physiologically-based pharmacokinetic models Physiologically-based pharmacokinetic models

ILSI Risk Science Institute Kinetics, Metabolism & Modes of Action: Ongoing/Planned Research Critical events/dose metrics/MoA – Critical events/dose metrics/MoA – FDA/NCTR – Linked to NTP bioassay FDA/NCTR – Linked to NTP bioassay NIEHS – CYP 2E1 null mouse studies NIEHS – CYP 2E1 null mouse studies Metabolism/kinetics in humans – Metabolism/kinetics in humans – Several groups – RTI, CDC/NHANES, Stockholm U., Kaiserslautern U., others Several groups – RTI, CDC/NHANES, Stockholm U., Kaiserslautern U., others PBPK models – PBPK models – Kirman et al. (2003) – Rat model; others? Kirman et al. (2003) – Rat model; others?

ILSI Risk Science Institute Genetic Toxicity: Research Needs Identification and characterization of adducts of acrylamide and/or glycidamide with DNA and significant nuclear proteins Identification and characterization of adducts of acrylamide and/or glycidamide with DNA and significant nuclear proteins Biological relevance Biological relevance Species and dose dependence, in vitro and in vivo Species and dose dependence, in vitro and in vivo Investigation of mechanisms of specific effects (e.g., chromosomal effects, cell transformation) Investigation of mechanisms of specific effects (e.g., chromosomal effects, cell transformation)

ILSI Risk Science Institute Genetic Toxicity: Ongoing/Planned Research DNA and protein adducts – DNA and protein adducts – FDA/NCTR – DNA and protein adducts (including dose response) FDA/NCTR – DNA and protein adducts (including dose response) Industry – DNA adducts in vitro and in vivo Industry – DNA adducts in vitro and in vivo Genetic toxicity mechanisms – Genetic toxicity mechanisms – FDA/NCTR - In vivo mutagenicity in Big Blue and tk+/- mice FDA/NCTR - In vivo mutagenicity in Big Blue and tk+/- mice Industry - Interaction with kinesin-related proteins Industry - Interaction with kinesin-related proteins

ILSI Risk Science Institute Reproductive and Developmental Toxicity: Research Needs Dose-response data for germ cell toxicity in rodents Dose-response data for germ cell toxicity in rodents Role of acrylamide vs. glycidamide Role of acrylamide vs. glycidamide Further examination of potential for developmental neurotoxicity Further examination of potential for developmental neurotoxicity

ILSI Risk Science Institute Reproductive and Developmental Toxicity: Ongoing/Planned Research Germ cell toxicity – Germ cell toxicity – NIEHS – CYP 2E1 null mouse dominant lethal study NIEHS – CYP 2E1 null mouse dominant lethal study Developmental neurotoxicity – Developmental neurotoxicity – FDA/NCTR – TBD FDA/NCTR – TBD Academic – Mechanistic studies Academic – Mechanistic studies

ILSI Risk Science Institute Carcinogenicity: Research Needs Confirm and clarify carcinogenicity in standard rodent models Confirm and clarify carcinogenicity in standard rodent models Pathology working group review Pathology working group review Assess effects of perinatal exposure Assess effects of perinatal exposure Develop enhanced data for dose-response assessment Develop enhanced data for dose-response assessment Determine mechanisms of induction of key tumors Determine mechanisms of induction of key tumors

ILSI Risk Science Institute Carcinogenicity: Ongoing/Planned Research Clarify carcinogenicity – Clarify carcinogenicity – NTP/NCTR – Well-designed 2-year studies of acrylamide in rats and mice NTP/NCTR – Well-designed 2-year studies of acrylamide in rats and mice NTP/NCTR – Neonatal mouse studies (acrylamide and glycidamide) NTP/NCTR – Neonatal mouse studies (acrylamide and glycidamide) NIEHS – PWG review of previous studies? NIEHS – PWG review of previous studies? Mechanisms – Mechanisms – NTP/NCTR – In conjunction w/2-year studies? NTP/NCTR – In conjunction w/2-year studies? Industry – Thyroid, brain, cell proliferation Industry – Thyroid, brain, cell proliferation

ILSI Risk Science Institute Neurotoxicity: Research Needs Relationships between dose, duration, and effect-levels and onset of neurotoxicity Relationships between dose, duration, and effect-levels and onset of neurotoxicity Determine effects of low-level, long-term dietary exposures Determine effects of low-level, long-term dietary exposures Link damage at cellular/tissue level with functional changes Link damage at cellular/tissue level with functional changes Mechanisms of neurotoxicity Mechanisms of neurotoxicity Role of acrylamide vs. glycidamide vs. ? Role of acrylamide vs. glycidamide vs. ? Bridge effects in animals and humans Bridge effects in animals and humans

ILSI Risk Science Institute Neurotoxicity: Ongoing/Planned Research Dose/duration/effect/onset – Dose/duration/effect/onset – FDA/NCTR – Ancillary studies with 2-year rodent bioassays to assess cumulative damage from low-level dietary exposures? FDA/NCTR – Ancillary studies with 2-year rodent bioassays to assess cumulative damage from low-level dietary exposures? Mechanisms - Mechanisms - Academic – Nerve terminal damage, axonal transport, key proteins, etc. Academic – Nerve terminal damage, axonal transport, key proteins, etc. NIEHS – CYP 2E1 null mouse, antioxidant, Phase II enzyme inhibitor NIEHS – CYP 2E1 null mouse, antioxidant, Phase II enzyme inhibitor NIOSH – Markers in exposed workers NIOSH – Markers in exposed workers

ILSI Risk Science Institute Epidemiology: Research Needs Study new or previously evaluated exposed worker cohorts for specific effects Study new or previously evaluated exposed worker cohorts for specific effects Link biomarkers of exposure with effects in workers Link biomarkers of exposure with effects in workers Assess feasibility and design criteria for study of acrylamide exposure/effects in non-occupationally exposed populations Assess feasibility and design criteria for study of acrylamide exposure/effects in non-occupationally exposed populations

ILSI Risk Science Institute Epidemiology: Ongoing/Planned Research Specific effects in workers – Specific effects in workers – NIOSH – Reproductive and neurobehavioral NIOSH – Reproductive and neurobehavioral Industry – Reassessment of published studies Industry – Reassessment of published studies Biomarkers – Biomarkers – NIOSH – Biomarkers included NIOSH – Biomarkers included Feasibility/design of study of non- occupationally exposed population – Feasibility/design of study of non- occupationally exposed population – CDC/NHANES, EPIC CDC/NHANES, EPIC See, e.g., Mucci et al., 2003 See, e.g., Mucci et al., 2003

ILSI Risk Science Institute Conclusions Ongoing/planned research (including FDA/NCTR work) will address many of the important toxicology research needs. Ongoing/planned research (including FDA/NCTR work) will address many of the important toxicology research needs. Key objectives include developing PBPK model for humans and understanding the significance of high-dose carcinogenic and neurotoxic effects for low-level exposures to acrylamide in foods. Key objectives include developing PBPK model for humans and understanding the significance of high-dose carcinogenic and neurotoxic effects for low-level exposures to acrylamide in foods.