Environmental Health - Toxic Substances Hydrology Program
In two separate studies, U.S. Geological Survey (USGS) scientists demonstrated that hormones such as estrogen can biodegrade in stream and groundwater environments. This is an important finding because the science, regulatory, and environmental communities have concerns about the environmental fate of endocrine-disrupting chemicals, such as hormones, in the human wastewaters discharged to the environment from wastewater treatment plants and domestic septic systems. The natural female sex hormone17ß-estradiol (estrogen) is made in the human body, and is an important chemical messenger related to female sexual development and reproduction. When concentrated in the environment by the disposal of treated wastewaters there is concern that elevated levels of 17ß-estradiol and other estrogenic chemicals can cause feminization of fish and wildlife exposed to the chemicals. Even though hormones are generally present in the environment near wastewater releases to streams and groundwater, they tend to absorb to sediment and/or degrade during transport.
USGS scientists published the results of a study in Environmental Science and Technology that demonstrated there is a significant potential for the biodegradation of three hormones, estrone, 17ß-estradiol, and testosterone, in the bottom sediments of streams that received wastewater from sewage treatment plants (Bradley and others, 2009). Laboratory experiments showed that all three compounds were efficiently degraded in surface water sediments under conditions where oxygen is present.
USGS scientists documented in Environmental Science and Technology that 17ß-estradiol biodegrades in the groundwater of a sandy aquifer on Cape Cod, Massachusetts, contaminated with wastewater from a sewage treatment plant (Barber and others, 2009). The scientists tested the ability of 17ß-estradiol to be transported in groundwater by injecting a solution of non-degrading tracer (bromide) and 17ß-estradiol into the subsurface. The resulting subsurface plume or cloud of tracer was allowed to move naturally with the groundwater. As the plume drifted it was monitored via multilevel samplers (see diagram). The results showed that the subsurface movement of 17ß-estradiol was retarded (reduced) when compared to bromide. Laboratory degradation experiments confirmed that the 17B-estradiol was being degraded by naturally occurring bacteria.
The results of these two studies indicate that biodegradation may give surface water and groundwater environments a natural capacity to reduce the levels of hormones in impacted streams and groundwater and reduce the potential impacts on fish and wildlife.
Barber, L.B., Keefe, S.H., LeBlanc, D.R., Bradley, P.M., Chapelle, F.H., Meyer, M.T., Loftin, K.A., Kolpin, D.W., and Rubio, F., 2009, Fate of sulfamethoxazole, 4-nonyphenol, and 17ß-estradiol in groundwater contaminated by wastewater treatment plant effluent: Environmental Science and Technology, v. 43, no. 13, p. 4843-4850, doi:10.1021/es803292v.
Bradley, P.M., Barber, L.B., Chapelle, F.H., Gray, J.L., Kolpin, D.W., and McMahon, P.B., 2009, Biodegradation of 17ß-estradiol, estrone and testosterone in stream sediments: Environmental Science and Technology, v. 43, no. 6, p. 1902-1910, doi:10.1021/es802797j.