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 are 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

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

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

Receptor Mediated Agonistic & Antagonistic Pesticides PCBs/TCDD/NP/BisPA Altered Enzyme Action Nitrate/nitrite Pesticides Phthalates Altered Metabolism Pesticides Altered Hormone Availability PCBs/PBBs Altered Gene Expression Nitrates/nitrite Pesticides PCBs Mechanisms of Endocrine Disruption 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 McLachlan, Endocrine Reviews.

Multiple Endogenous Hormones CLASSHormonePotency Androgens 5  -dihydrotestosterone (DHT) 100% Testosterone (T) 50% Androstenedione (A4)8% Dehydroepiandrosterone (DHA) 4% Estrogens Estradiol-17  (E 2 )100 % Estriol (E 3 )10% Estrone (E 1 )1% Progestins Progesterone (P) 100% 17  -hydroxyprogesterone (17  -OHP)40-70% 20  -hydroxyprogesterone (20  -OHP)5% Thyroid Thyroxin (T4)10% Triiodothyronine (T3)100%

Species-specific Hormonal Variation

Species-specific Effects

Multiple Related Endogenous Receptors Modified from McLachlan, Endocrine Reviews.

Estrogen-like Receptor Variation Modified from McLachlan, 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 Modified from Kiesecker, 2002 MPCA photo

EDCs & Salamander Deformities

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

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

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

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