Final Report (2000-MS-2-M2)- Tarrant et al
Summary: A study that asks whether Irish rivers contain estrogenic compounds. If so, at what concentrations? Are these levels likely to pose a threat to aquatic ecosystems, particularly wild fish? Is there a risk to drinking water supplies?
The objective of this study was to provide an assessment of the potential risk from endocrine disrupting compounds (EDCs) to Irish freshwaters, their ecosystems and associated drinking water resources. The different elements of the study are integrated in a manner designed to answer the following questions:
Chapter 1 thoroughly reviews the current literature in the area and demonstrates that no research, prior to this study, had been carried out to address these questions in an Irish context.
Chapter 2: Details of the methodologies applied in this study are described.
Chapter 3: An in vivo caged fish study was performed to determine the effects of wastewater treatment plant (WWTP) effluent on exposed fish populations in Irish rivers, and any associated risk to drinking water resources. To this end, cages of male rainbow trout were deployed at test and control sites on the river Lee, and levels of plasma vitellogenin were used as a sensitive indicator of exposure to environmental estrogens. No evidence of estrogen exposure was found at any of the test or control sites, including the site at the intake to the Lee Road water treatment works, which supplies drinking water to Cork City.
Chapter 4 presents the results of a survey of feral Brown trout populations in the rivers Liffey, Lee and Bandon, and the Killarney Lakes. There was no evidence of exposure to environmental estrogens in any of the sites surveyed, with the exception of the Liffey site, located immediately downstream of Osberstown WWTP. Raised plasma vitellogenin levels in male fish taken from this site indicated estrogenic activity in this region of the river.
Chapter 5: An in vitro bioassay analysis of point sources of estrogens; namely WWTP effluents, and their impact on receiving waters, was performed. Estrogen levels in effluents ranged from 1-17 ng/l while receiving waters were less than 3 ng/l in all cases. These levels compared favourably with similar size plants investigated in other countries, including the UK. A model recently developed (2004) at CEH Wallingford predicts estrogenicity of effluents and receiving waters impacted by domestic waste. This model was applied for the first time in an Irish context. Generally, for effluents, agreement was good between measured and predicted values for estrogenicity. However, the model consistently under-predicted the measured concentration of estrogens in the receiving waters. Given the predominantly rural nature of the catchments involved, it is suggested that the additional estrogenic signal is derived from intensive livestock agriculture.
Chapter 6 presents a summary of the general conclusions from this study.
