Estrogenic Chemicals in Wastewater Dominated Streams and their Effects on Fishes and Other Life
AWRA Colorado Presentation – September 29, 2009
Dr. David O. Norris, Department of Integrative Physiology, University of Colorado at Boulder
Summary of Dr. Norris’ Presentation (By Bill Battaglin, USGS):
Humans and wildlife are exposed to a large number of natural and man-made contaminants. Humans have generated ~80,000 new chemicals. Some of these become environmental contaminants as a result of their use. Some environmental contaminants are endocrine active chemicals (EACs).
All body functions in humans and most other wildlife are controlled or affected by hormones. Hormones work at part-per-billion (microgram per liter) or part-per-trillion (nanogram per liter) concentrations in humans and wildlife. Estrogens are a class of steroid compounds that are important female sex hormones. Estrogens occur naturally, but there are other man-made chemicals that mimic estrogens such as some pesticides, plasticizers, phthalates, and pharmaceuticals. The mixture of natural and man-made estrogens tends to act additively in terms of their effects on non-target organisms.
Data from Boulder Creek showed that the downstream from the discharge of the Boulder waste-water treatment plant (WWTP) native fishes (white suckers) where feminized, that the sex ratio between males and females was not 1:1 but 1:5, and that some intersex fish were present. Subsequent analysis of museum records showed no evidence of reproductive disruption in white suckers collected between 50 and 100 years ago.
It is hard to control for the many variables that could affect native fishes in a natural setting , so David and his team built a trailer that they can house fish in that has the ability to control for temperature, oxygen levels, and food sources. Using this equipment they determined that a mixture of 50% effluent and 50% stream water resulted in feminization of fathead minnows after just 7 days of exposure. After this experiment the Boulder WWTP upgraded from a trickling filter system to an activated sludge system. A repeat of the earlier test showed that the fish were not affected by the mixture of 50% effluent and 50% stream water after 28 days.
David noted that a new report from the Endocrine Society summarized most of the current literature and concluded that there was reason for concern and need for additional research to determine how EACs are affecting humans and wildlife.
David concluded that exposure of hormones from drinking water is not likely to be a problem by itself. Unfortunately humans get exposed to EAC’s in food and directly as well. It is too early to tell if this a significant problem, but David argues that the precautionary principal should be invoked when dealing with these chemicals.