The study, conducted with the University of Idaho, appears in the June issue of Environmental Toxicology and Chemistry. Previous research reported that high concentrations of estrogen could change sex organs, causing juvenile male fish to develop female organs. Estrogen is an active ingredient in most oral contraceptives and often finds it way into surface waters through sewer systems. The PNNL study looked at the impact of a synthetic estrogen called ethynylestradiol, which is the chemical in oral contraceptives.
Irvin Schultz, PNNL toxicologist who led the study, said the research reinforces that impacts aren't limited to juvenile fish. "We can see that adult fish aren't immune to the effects of estrogen in waterways. Even short-term exposure to low levels of synthetic estrogen can impact their fertility," Schultz noted. "Our results indicate that the fertility of a healthy male trout that has developed normally still can be affected, if that exposure takes place during a critical sexual maturation stage before spawning."
In a controlled laboratory experiment, PNNL scientists from the lab's Marine Sciences Laboratory in Sequim, Wash., exposed adult male rainbow trout for 62 days to three different concentrations of ethynylestradiol -- 10, 100 and 1,000 nanograms per liter of water. The sperm of exposed fish were harvested then used in a controlled in-vitro fertilization process with eggs from a healthy female rainbow trout.
Contact: Staci Maloof
DOE/Pacific Northwest National Laboratory