|
|
|
The Instability of Estrogenic Chemicals During Laboratory Static Exposure Conditions With Male Fathead Minnows
 |
|
| Abstract: | Endocrine disrupting chemicals (EDCs) such as Para-nonylphenol (NP), estradiol (E2), estrone (E1), estriol (E3) and ethynylestradiol (EE2) are shown to be ubiquitous in surface waters, sediments and sludge. These EDCs are known to induce vitellogenin gene (Vg) expression in male fathead minnows. We have observed that the aforementioned EDCs are not stable during static laboratory conditions under high biomass to volume exposures at 25oC, with aeration at the rate of 100 bubbles minute-1 and a loading rate of 3 g fish Liter-1 instead of the standard rate of 0.5 g fish Liter-1. Male fat head minnows were exposed to NP at nominal concentrations for 24 hours and no detectable levels of vitellogenin gene (Vg) transcripts were seen. We checked the analytical values of NP in exposure water and found that measured values were only 2% of the nominal values. Additional experiments revealed that within 4 hours of exposure 98% of the NP was lost, of which 30% of nominal dose was bound to external body mucous of the fish and the remaining 68% was unaccounted. Subsequent analysis of E1, E2, E3 and EE2 under similar test conditions revealed that E1 and E3 showed losses similar to NP while, E2 and EE2 exhibited less concentration decline (20-30%). In order to maintain analytical concentrations close to the nominal concentrations, NP was supplemented continuously at appropriate concentrations by means of a peristaltic pump. Under this protocol, the final measured concentrations were close to 80% of the nominal dose and, in addition, Vg expression was observed in a dose dependant manner. These results show the importance of the exposure regimen in determining/interpreting the effects of EDCs in fish. |
|
| Citation: | Reddy, T. V., J. M. Lazorchak, M. E. Smith, P. E. Grimmett, D. F. Bender, B. E. Wiechman, and D. L. Lattier. The Instability of Estrogenic Chemicals During Laboratory Static Exposure Conditions With Male Fathead Minnows. Presented at Society of Environmental Toxicology & Chemistry, Portland, OR, November 14-18, 2004. |
|
|
| Contact: |
Linda Ransick - (513) 569-7395 or ransick.linda@epa.gov
|
|
| Division: |
Ecological Exposure Research Division |
|
| Branch: |
Molecular Ecology Research Branch |
|
| Product Type: |
Abstrct/Oral |
|
| Presented: |
11/15/2004 |
|
|
|
