Estrogens in Wastewater Treatment Plant Effluent
By Daniel D. Snow,
Manager of Laboratory Services
UNL Water Sciences Laboratory
University of Nebraska, Omaha environmental toxicologist Alan Kolok and University of Nebraska-Lincoln environmental chemist Daniel Snow, along with their graduate students, are in the second year of a two-year study to determine whether estrogenic compounds are released from wastewater treatment plants in Nebraska and whether these compounds occur at sufficient levels to feminize male fish.
Estrogens and other compounds that mimic female sex steroids control development of female reproductive systems including those of fish. For example, male fish exposed to estrogenic compounds can develop feminine traits such as production of egg proteins. Recent studies worldwide have found that estrogenic compounds may occur in wastewater effluent throughout Western Europe and North America at high enough levels to feminize male fish. The environmental implications of these findings are only just beginning to be understood.
In the first year of this Nebraska Department of Environmental Quality-funded study, specially designed passive samplers and caged fish were exposed to water above and below the effluent discharge from wastewater treatment plants in Hastings, Columbus and Grand Island, Nebraska.
The passive samplers, designed to simulate and measure exposure of aquatic organisms to a variety of contaminants, were extracted and analyzed at the UNL Water Sciences Laboratory for a suite of natural and synthetic steroid hormones.
Elevated levels of several natural estrogens were found in the passive sampler below the Hastings plant effluent. Lower, but still detectable, levels of these compounds were also found in samplers exposed to effluent below the Grand Island treatment plant while none were found in the sampler exposed to the Columbus plant effluent, as well as three control sites not impacted by wastewater.
To better understand the biological effects, caged adult male minnows exposed to the same effluent were analyzed in Kolok’s laboratory for the presence of egg precursor proteins.
These proteins are normally found only in female fish, and would only be evident in males exposed to significant levels of estrogenic compounds. The proteins were found only in male fish exposed to effluent from the Hasting wastewater treatment plant. The development of feminine traits by male fish exposed to effluent paired with the results from the passive samplers compounds suggests that the effect is linked to the presence of estrogenic compounds.
A follow-up study on the presence of estrogenic compounds in the waterways of Nebraska is being conducted this summer to validate these results. Feminization of male minnows observed in this study may be used to understand the potential for reproductive impairment in other species of fish in Nebraska waterways.
