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Reproductive Toxicology Division
Reproductive Toxicology Division
Abnormal Development Team (ARD)
Overview
This research program is focused on three issues:
- The mechanisms of toxicant-induced abnormal reproductive development
- How to detect and monitor EDCs in effluents
- Development and use of recombinant receptors for interspecies extrapolation
The team’s research is focused on the following Long-Term Goals (LTG) in EPA’s Multi-Year Plans (MYP):
- MYP: Endocrine Disruptors
- LTG 1: Provide a better understanding of the science underlying the effects, exposures, assessment and management of EDCs.
- LTG 2: Determine the extent of the impact of endocrine disruptors on humans, wildlife, and the environment.
- LTG 3: Support EPA’s screening and testing programs.
- LTG 1: Provide a better understanding of the science underlying the effects, exposures, assessment and management of EDCs.
- MYP: Human Health
- LTG 2: Characterize aggregate and cumulative risk in order to manage risk to humans exposed to multiple environmental stressors (mixtures)
- Team Leader
- Earl Gray, Research Biologist Biosketch
- Principal Investigators
- Research Support
- Post-Doctoral Trainees
ARD Team Projects
Cellular and Molecular Mechanisms of Abnormal Reproductive Development
Contact: Earl Gray
Efforts in this project are directed towards determining whether EPA’s testing guidelines adequately evaluate potential endocrine-mediated effects, especially during critical periods of reproductive development. The project’s objectives include: (1) conducting studies to evaluate the strengths and weaknesses of the alternative multigenerational or transgenerational protocols as compared to the standard EPA Multigenerational Reproductive Test; (2) determining the No Adverse Effect Level (NOAEL) for Endocrine Disrupting Chemicals (EDCs) in F1 female and male rat offspring using a transgenerational protocol; (3) identifying sensitive endpoints that could be added to a standard multigenerational test to enhance the detection of chemicals that have adverse modes of action including fetal endocrine and genomic measures; and (4) recommending improvements in the experimental design of multigenerational tests enabling them to be more sensitive but use fewer animals. Related studies also provide a framework for assessment of the utility of alternative enhanced in utero-lactational protocols for the Agency as requested by the Endocrine Disruptor Screening and Testing Advisory Committee (EDSTAC).
Cumulative Reproductive Effects of In Utero Administration of Mixtures of Antiandrogens in Male Sprague Dawley Rats: Synergy or Additivity?
Contact: Earl Gray
The 1996 Food Quality Protection Act (FQPA) requires the EPA to consider the cumulative risk of chemicals that act via a common mode or mechanism of action. As a response, work in this project involves conducting studies with mixtures in order to provide a framework for assessing the cumulative effects of in utero exposure to “antiandrogenic” Endocrine Disrupting Chemicals (EDCs). Two methods are being used to predict the “expected” outcome of a mixture on reproductive endpoints. In the first method, relative potency factors (RPFs) are generated for each chemical in relation to a reference chemical. In the second approach, mixture effects can be predicted using either a concentration addition model or a mixed model that includes both concentration and response addition.
In Vitro Screening of Environment Samples for Estrogenic and Androgenic Activity: Concentrated Animal Feeding Operation (CAFO), Pulp Mill, and Treated Sewage Effluents; Global Water Research Coalition (GWRC) Samples; and Combustion Byproducts.
Contact: Vickie Wilson
The major question addressed by this project is whether in vitro receptor binding and acivation assays can be used to assess Endocrine Disrupting Chemical (EDC) activity in environmental samples as a screen for potential effects on fish, wildlife, and human health. In this project, environmental samples are being evaluated for EDC activities in order to (1) identify the potency of the samples; (2) attempt to identify specific chemicals in samples responsible for EDC activity; and (3) determine the potential impacts of these chemicals on fish, wildlife, and human health. Due to the complex composition of the effluents, chemical identification, in most cases, is guided by the cell-based bioassays that can pinpoint hormonally active sample fractions. EDC activity, including androgenic and estrogenic activity, has been identified in several environmental samples. Initial studies demonstrated androgenic activity in pulp and paper mill effluents which correlated with the presence of masculinized female fish downstream from the plant. Further work established androgenic activity in beef feedlot operation run-off and in diesel fuel combustion by-products.
Interspecies Extrapolation: Species Diversity in Ligand Binding and Gene Expression Using Recombinant-derived Steroid Hormone Receptors
Contact: Phillip Hartig
Previous work has indicated that significant differences exist among different vertebrate species for the affinity of various toxicants for the estrogen receptor (ER) and androgen receptor (AR). The EPA’s Endocrine Disruptor Screening Program is encouraging the development of mammalian ER and AR binding assays that do not require animals as the source of receptor protein. Investigators in this research program have developed cell based, gene expression assays using recombinant receptors which can distinguish estrogens from anti-estrogens and androgens from anti-androgens. In this project, work is in progress to develop AR and ER binding assays from representative species from several classes of vertebrates and invertebrates. The AR and ER of several animals have been isolated and sequenced, and competitive binding assays have been run with AR from those species. These cross-species comparisons will facilitate the identification of Endocrine Disrupting Chemicals EDCs that may differentially affect various species and aid in the development and support of future EPA risk assessment decisions.
Recent Publications
Publications are listed in reverse chronological order. The names of current RTD investigators are in bold.
Orlando EF, Bass DE, Caltabiano LM, Davis WP, Gray LE, Guilette LJ. 2007. Altered development and reproduction in mosquitofish exposed to pulp and paper mill effluent in the Fenholloway River, Florida USA. Aquat Toxicol. 84:399-405. Abstract
Wilson VS, Howdeshell K, Lambright CS, Furr JR, Gray LE. 2007. Differential expression of the phthalate syndrome in male Sprague Dawley and Wistar rats after in utero DEHP exposure. Toxicol Lett. 170:177-184. Abstract
Howdeshell K, Furr JR, Lambright CS, Wilson VS, Gray LE. 2007. Cumulative effects of dibutyl phthalate and diethylhexyl phthalate on male rat reproductive tract development: Altered fetal steroid hormones and genes. Toxicol Sci. 99:190-202. Abstract
Blystone C, Lambright CS, Howdeshell K, Furr JR, Sternberg RM, Butterworth BC, Durhan EJ, Makynen EA, Ankley GT, Wilson VS, Leblanc GA, Gray LE. 2007. Sensitivity of fetal rat testicular steroidogenesis to maternal prochloraz exposure and the underlying mechanism of inhibition. Toxicol Sci. 97:512-519. Abstract
Hotchkiss AK, Lambright CS, Ostby JS, Parks-Saldutti L, Vandenbergh JG, Gray LE. 2007. Prenatal testosterone exposure permanently masculinizes anogenital distance, nipple development, and reproductive tract morphology in female Sprague-Dawley rats. Toxicol Sci. 96:335-45. Abstract
Wilson VS, Cardon MC, Gray LE, Hartig PC. 2007. Competitive binding comparison of endocrine-disrupting compounds to recombinant androgen receptor from fathead minnow, rainbow trout, and human. Environ Toxicol Chem. 26:1793-802. Abstract
Blystone C, Furr JR, Lambright CS, Ryan BC, Howdeshell K, Wilson VS, Leblanc GA, Gray LE. 2007. Prochloraz inhibits testosterone production at dosages below those that affect androgen-dependent organ weights or the onset of puberty in the male Sprague Dawley rat. Toxicol Sci. 97:65-74. Abstract
Owens W, Gray LE, Zeiger E, Walker M, Yamasaki K, Ashby J, Jacob E. 2007. The OECD program to validate the rat Hershberger bioassay to screen compounds for in vivo androgen and antiandrogen responses: Phase 2 dose-response studies. Environ Health Perspect. 115:671-8. Abstract
Owens CV, Lambright C, Cardon M, Gray LE, Gullett BK, Wilson VS. 2006. Detection of androgenic activity in emissions from diesel fuel and biomass combustion. Environ Toxicol Chem. 25:2123-31. Abstract
Owens W, Zeiger E, Walker M, Ashby J, Onyon L, Gray LE. 2006. The OECD program to validate the rat Hershberger bioassay to screen compounds for in vivo androgen and antiandrogen responses. Phase 1: Use of a potent agonist and a potent antagonist to test the standardized protocol. Environ Health Perspect. 114:1259-65. Abstract
Gray LE, Laskey JW, Ostby J. 2006. Chronic di-n-butyl phthalate exposure in rats reduces fertility and alters ovarian function during pregnancy in female Long Evans hooded rats. Toxicol Sci. 93:189-195. Abstract
Silva MJ, Kato K, Wolf CJ, Samandar E, Silva SS, Gray LE, Needham LL, Calafat AM. 2006. Urinary biomarkers of di-isononyl phthalate in rats. Toxicology. 223:101-112. Abstract
Gray LE, Wilson VS, Stoker TE, Lambright CS, Furr JR, Noriega NC, Howdeshell K, Ankley GT, Guillette L. 2006. Adverse effects of environmental antiandrogens and androgens on reproductive development in mammals. Int J Androl. 29:96-104; 105-8. Abstract
Hotchkiss AK, Parks LG, Ostby JS, Lambright CS, Furr JR, Vandenberg JJ, Gray LE. 2004. A mixture of the “antiandrogens” linuron and butyl benzyl phthalate alters sexual differentiation of the male rat in a cumulative fashion. Biol Reprod. 71:1852-1861. Abstract
Gray LE, Wilson VS, Stoker TE, Lambright CS, Furr JR, Noriega NC, Hartig PC, Cardon MC, Rosen MB, Ankley GT, Hotchkiss AK, Orlando EF, Guilette LJ, Kelce W. 2004. Environmental androgens and antiandrogens: An expanding chemical universe. In: R.Naz, editors. Endocrine Disruptors. 2nd Edition. Boca Raton, (FL): CRC Press LLC. p 313-345.
Noriega NC, Ostby JS, Lambright CS, Wilson VS, Gray LE. 2005. Late gestational exposure to the fungicide prochloraz delays the onset of parturition and causes reproductive malformations in male rat offspring. Biol Reprod. 72:1324-1335. Abstract
Wilson VS, Bobseine KL, Gray LE. 2004. Development and characterization of a cell line that stably expresses an estrogen-responsive luciferase reporter for the detection of estrogen receptor agonist and antagonists. Toxicol Sci. 81:69-77. Abstract
Wilson VS, Cardon MC, Thornton J, Korte JJ, Welch JE, Gray LE, Hartig PC. 2004. Cloning, expression and characterization of the 2androgen receptor and isolation of estrogen receptor alpha from the fathead minnow (pimephales promelas). Environ Sci Technol. 38:6314-21. Abstract