Models Markers and Mechanisms Understanding Endocrine Disruptor Effects

Models, Markers and Mechanisms: Understanding Endocrine Disruptor Effects Brent D. Palmer, Ph. D. Associate Professor of Environmental Biology Department of Biology University of Kentucky

Endocrine Disrupting Compounds EDCs • An endocrine disruptor – an exogenous substance or mixture that alters function(s) of the endocrine system and consequently causes adverse health effects in an intact organism, or its progeny, or (sub)populations. • A potential endocrine disruptor – an exogenous substance or mixture that possesses properties that might be expected to lead to endocrine disruption in an intact organism, or its progeny, or (sub)populations.

95 Known Endocrine Disruptors • • • 10 Persistent Organohalogens 1 Food antioxidant 57 Pesticides 4 Phthalates 10 Other industrial compounds 4 Metals

87, 000 Potential EDCs EPA estimates that there approximately 87, 000 chemicals to be screened for EDC effects • • 75, 500 industrial chemicals 900 pesticide active ingredients 2, 500 other pesticide ingredients 8, 000 cosmetics, food additives and nutritional supplements.

Human Endpoints of Concern • Sexual Development • Fertility and Reproductive Impairments • Nervous System and Behavioral Changes • Immune function • Cancer induction

Female EDC Effects • Impaired fertility • Endocrine dysfunction – Altered hormone profiles • Ovary & reproductive tract structure – increasing incidence of uterine and oviduct abnormalities • Endometriosis • Age at puberty

Female EDC Effects • Brain and behavior – Altered IQ and behavior, including sexual behaviors • Cancer – increasing incidence of breast cancer & reproductive tract cancers • Immune dysfunction • Multigenerational effects

Male EDC Effects • Declining fertility – Declining sperm counts? • Endocrine dysfunction – Altered hormone profiles • Testis & reproductive tract structure – increasing incidence of hypospadias and cryptochidism • Age of Puberty

Male EDC Effects • Brain and behavior – Altered IQ and behavior, including sexual behaviors • Cancer – increasing incidence of testicular & prostate cancers • Immune dysfunction • Multigenerational effects

Molecular Biosphere seconds eons Cellular Ecosystem Biomarkers minutes centuries Tissue Community hours Organ decades Organism years Modified from Guillette, UF Animal Models Population Emergent Effects Mechanisms Levels of Effects

Targets for Endocrine Disruption • • Hormones Binding proteins Receptors Signal transduction pathways EDCs SEX

Mechanisms of Endocrine Disruption • Receptor Mediated Agonistic & Antagonistic • Pesticides • PCBs/TCDD/NP/Bis. PA • Altered Enzyme Action • Nitrate/nitrite • Pesticides • Phthalates • Altered Metabolism • Pesticides • Altered Hormone Availability • PCBs/PBBs • Altered Gene Expression • Nitrates/nitrite • Pesticides • PCBs Guillette, UF

Complications to understanding the effects of EDCs • Hormones – Multiple endogenous hormones – Species-specific hormone variation – Species-specific hormone effects • Receptors – Multiple related endogenous receptors – Species- and tissue-specific receptor variation

Hormones types • • Estrogens Androgens Progestins Corticosteroids • • Amines Peptides Proteins Glycoproteins

Environmental EDCs Modified from Mc. Lachlan, 2001. Endocrine Reviews.

Multiple Endogenous Hormones CLASS Androgens Hormone Potency 5 -dihydrotestosterone (DHT) Testosterone (T) Androstenedione (A 4) Dehydroepiandrosterone (DHA) 100% 50% 8% 4% Estrogens Estradiol-17 (E 2) Estriol (E 3) Estrone (E 1) 100 % 10% 1% Progestins Progesterone (P) 100% 17 -hydroxyprogesterone (17 -OHP) 40 -70% 20 -hydroxyprogesterone (20 -OHP) 5% Thyroid Thyroxin (T 4) Triiodothyronine (T 3) 10% 100%

Species-specific Hormonal Variation

Species-specific Effects

Multiple Related Endogenous Receptors Modified from Mc. Lachlan, 2001. Endocrine Reviews.

Estrogen-like Receptor Variation Modified from Mc. Lachlan, 2001. Endocrine Reviews.

Dose-Response Relationships

Non-Monotonic Dose-Response Curves

Non-Monotonic dose-response curves Redrawn from vom Saal, et al. , PNAS, 1997

Additive Effects of Mixtures Modified from Silva et al. , 2002, EST

Timing of Exposure Organizational • Endocrine system regulates anatomical and physiological development Activational • Endocrine system regulates homeostasis and reproduction

Critical Windows of Exposure

EDCs and Immune Function MPCA photo Modified from Kiesecker, 2002

EDCs & Salamander Deformities

Molecular Biosphere seconds eons Cellular Ecosystem Biomarkers minutes centuries Tissue Community hours Organ decades Organism years Modified from Guillette, UF Animal Models Population Emergent Effects Mechanisms Levels of Research

Multigenerational Effects Modified from Rio Gomez et al. , 2002, Lancet

Altered variance of stressed populations Modified from Orlando & Guillette, 2001

EDCs and Salamander Behavior

EDCs and Salamander Behavior

Atrazine and Osmoregulation

Conclusions • New paradigms – Low dose effects – Critical windows of exposure – Complex mixtures – Chronic effects – Multigenerational effects Time Magazine, 1947

Conclusions • Future Areas – Novel/Emergent effects – Effects on other hormone systems – Effects on other species – Altered variance/ subpopulation effects – Ecological impacts – Screen new compounds

PCB Production versus Research Publications

Conclusions • Human Effects – Low-levels effects are critical • particularly embryonic exposures – Many additional hormone systems may be impacted – Novel endpoints need to be identified – Exposure is ubiquitous

Global Perspective

Acknowledgements • • • Univ. of Kentucky U. S. EPA NIEHS NSF Adria Elskus Brian Shepherd • • • Jason Rohr Andy Sih Phil Crowley Lou Guillette Sylvia Palmer Tyler Sager