Special Symposium: Hormones in the Environment at the SETAC North America 2010 Annual Meeting
Susan Laessig (U.S. Environmental Protection Agency, Office of Pollution Prevention and Toxics) and Dan Snow (University of Nebraska at Lincoln)
Advances in analytical chemistry now make it possible to detect hormones and their metabolites in the environment and to measure lower concentrations in water, air and soil than ever before. Synthetic and natural estrogens, such as estradiol and ethinylestradiol, can be found in waterways near municipal wastewater treatment plants and synthetic androgens, such as the anabolic steroid trenbolone, are detected in waste and runoff from animal feeding operations. Steroid hormones have also preliminarily been measured in the air downwind from animal feed lots. Estrogenic and androgenic steroid hormones may cause adverse effects in fish at very low water concentrations and are of concern for wildlife populations because of their biological activity at very low concentrations.
This special symposium examined what is known about the factors that influence fate and transport of natural and synthetic hormones in the environment and the potential impacts on wildlife and aquatic ecosystems. Speakers focused on natural and synthetic steroid hormones as well as other contaminants produced and released from concentrated animal feeding operations (CAFOs) raising beef and dairy cattle, swine and poultry, and examined:
- Major human sources of steroid hormones, tracing and quantifying hormone entry into the environment.
- Factors that could affect the transport and fate of steroid hormones including the impact of hormones on biological receptors such as fish and turtles.
- Aspects of human practices that can alter the entry of steroid hormones to water and air, and that can lead the way to better agricultural and land management practices.
Cattle CAFOs were studied in several areas of the U.S. In Nevada, the occurrence, accumulation, degradation and mobility of trenbolone acetate metabolites at beef CAFOs were assessed using rainfall simulators and field sampling. Trenbolone metabolites were found to undergo significant degradation on the surface and mass balance modeling estimated that concentrations of 100-1,000 ng/L in leachate are possible. In Indiana, synthetic androgens are not frequently detected in drainage ditches downstream from beef and dairy CAFOs, while estrogens, particularly estrone, are common at concentrations around 1 ng/L. Application of manure to adjacent fields leads to increased concentrations of steroid hormones in tile drains with rain events and flow being a significant factor. Interestingly, progesterones were recently detected in runoff from cattle CAFOs in Wisconsin at concentrations up 1,100 ng/L. Soil was found to contain very low or non-detectable levels of steroid hormones. In waterways associated with CAFO runoff and elevated steroid hormone concentrations, species richness and reproductive fitness is reduced in native populations of fish. Exposure of fish to CAFO runoff did not affect adult fish, but skewed the sex ratio towards males in fish embryos. A recently funded study in Texas is analyzing steroid hormones in air and dust near cattle feedlots in this dry, windy region and has detected several synthetic hormones in particulate matter used as growth promoters in the samples. This also raises health issues for human living in proximity to CAFOs in dry areas.
Poultry CAFOs have been studied in Maryland on the Delmarva Peninsula where intense agriculture produces about 600 million birds annually. Because the majority of the 700 million tons of poultry litter is land applied to agricultural fields, impacts on regional surface and groundwater quality are a large concern. Poultry litter contains natural steroid hormones produced by the breeding birds. The estrogenic activity of runoff from fields where litter was applied was shown to increase for several days before declining and it is hypothesized that deconjugation to bioactive estrone and estradiol occurs before degradation. Incorporation of manure into the top eight inches of the soil using Turbo Till reduced runoff of both nutrients and estrogens, but the reduction was affected by the timing and intensity of rainfall. In northern climates, such as North Dakota, winter application of waste to fields results in increased runoff of nutrients and hormones during winter snow melt and rain events. Soil type and application rates affect the concentration in runoff, but nutrients were found to track similarly with hormone levels.
Some regions, such as North Carolina, contain large numbers of swine CAFOs that may also produce natural steroid hormones during the breeding cycle. In order to develop a mass balance Bayesian model for estrogens in swine production, concentrations of estrogens are being measured as swine waste moves from the pens, to the lagoon, to field applications, and in runoff. Increased estrogen activity has been associated with gestating and lactating sows in farrowing houses. Waste from the houses is washed into lagoons where biotransformation of estrogens might occur. Estrogens were found to partition onto lagoon particulates and when applied to agricultural land, the concentrations of estrogens attenuated in soil. The data suggested that seasonal variations in animal estrogen output and in lagoon estrogen bioavailability were possible.
Future research on hormones in the environment will seek to interpret the data from hormone concentrations in the various environmental compartments in terms of specific agricultural practices in order to identify ways to reduce impacts on aquatic life and ecosystems.
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