Abstract
Testicular oocytes in wild adult bass (Micropterus spp.) are considered a potential indication of exposure to estrogenic compounds in municipal, agricultural, or industrial wastewater. However, our ability to interpret links between testicular oocyte occurrence in wild fish species and environmental pollutants is limited by our understanding of normal and abnormal gonadal development. We previously reported low-to-moderate testicular oocyte prevalence (7%-38%) among adult male bass collected from Minnesota waters with no known sources of estrogenic compounds. In the present study, two experiments were conducted in which smallmouth bass (Micropterus dolomieu) fry were exposed to control water or 17-α-ethinylestradiol (EE2) during gonadal differentiation, then reared in clean water for an additional period. Histological samples were evaluated at several time points during the exposure and grow-out periods, and the sequence and timing of gonadal development in the presence of estrogen were compared with that of control fish. Testicular oocytes were not observed in any control or EE2-exposed fish. Among groups exposed to 1.2 or 5.1 ng/L EE2 in Experiment 1 or 3.0 ng/L EE2 in Experiment 2, ovaries were observed in 100% of fish up to 90 days after exposure ceased, and approximately half of those ovaries had abnormal characteristics, suggesting that they likely developed in sex-reversed males. Groups exposed to 0.1, 0.4, or 1.0 ng/L in Experiment 2 developed histologically normal ovaries and testes in proportions not significantly different from 1:1. These findings suggest that, while presumably able to cause sex reversal, juvenile exposure to EE2 may not be a unique cause of testicular oocytes in wild bass, although the long-term outcomes of exposure are unknown. Environ Toxicol Chem 2022;41:1416-1428. © 2022 SETAC. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1416-1428 |
| Number of pages | 13 |
| Journal | Environmental Toxicology and Chemistry |
| Volume | 41 |
| Issue number | 6 |
| DOIs | |
| State | Published - Jun 2022 |
Bibliographical note
Funding Information:The present study was prepared using federal funds awarded to Patrick Schoff, Jennifer Olker, and Sarah Kadlec (NA10OAR4170069, Minnesota Sea Grant, National Sea Grant College Program, National Oceanic and Atmospheric Administration, U.S. Department of Commerce), with laboratory space, equipment, and additional expertise provided by the Environmental Protection Agency Office of Research Great Lakes Toxicology and Ecology Division in Duluth, MN. We are extremely grateful to the following people who were critical to the success of these experiments. J. Haselman (US EPA‐ORD‐CCTE‐GLTED) built and configured the exposure system. B. Borkholder and others from the Fond du Lac Band of Lake Superior Chippewa Resource Management Division located and collected smallmouth bass fry. P. Kosian and J. Korte (EPA‐GLTED) developed the EE2 ELISA analysis method. K. Lott (Badger Technical Services, Duluth, MN) provided laboratory support. J. Swintek (Badger Technical Services, Duluth, MN) and R. Erickson (EPA‐GLTED) provided statistical analysis and consultation. Security personnel from Shield Services (Duluth, MN) monitored the exposure system after hours. S. Driscoll and K. Axler (University of Minnesota – Duluth, Natural Resources Research Institute) provided field assistance. R. Kunz (University of Minnesota – Duluth) provided laboratory assistance. Finally, we thank K. Flynn (EPA‐GLTED) and D. Papoulias (USGS CERC, retired) for providing comments on an earlier draft.
Funding Information:
The present study was prepared using federal funds awarded to Patrick Schoff, Jennifer Olker, and Sarah Kadlec (NA10OAR4170069, Minnesota Sea Grant, National Sea Grant College Program, National Oceanic and Atmospheric Administration, U.S. Department of Commerce), with laboratory space, equipment, and additional expertise provided by the Environmental Protection Agency Office of Research Great Lakes Toxicology and Ecology Division in Duluth, MN. We are extremely grateful to the following people who were critical to the success of these experiments. J. Haselman (US EPA-ORD-CCTE-GLTED) built and configured the exposure system. B. Borkholder and others from the Fond du Lac Band of Lake Superior Chippewa Resource Management Division located and collected smallmouth bass fry. P. Kosian and J. Korte (EPA-GLTED) developed the EE2 ELISA analysis method. K. Lott (Badger Technical Services, Duluth, MN) provided laboratory support. J. Swintek (Badger Technical Services, Duluth, MN) and R. Erickson (EPA-GLTED) provided statistical analysis and consultation. Security personnel from Shield Services (Duluth, MN) monitored the exposure system after hours. S. Driscoll and K. Axler (University of Minnesota – Duluth, Natural Resources Research Institute) provided field assistance. R. Kunz (University of Minnesota – Duluth) provided laboratory assistance. Finally, we thank K. Flynn (EPA-GLTED) and D. Papoulias (USGS CERC, retired) for providing comments on an earlier draft.
Publisher Copyright:
© 2022 SETAC. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.
Keywords
- Developmental toxicity
- Endocrine disrupting compounds
- Estrogenic compounds
- Ethinylestradiol
- Histopathology
- Bass
- Water
- Water Pollutants, Chemical/analysis
- Disorders of Sex Development/pathology
- Male
- Ethinyl Estradiol/toxicity
- Rivers
- Estrogens/toxicity
- Animals
PubMed: MeSH publication types
- Journal Article
