EDCs alter US water quality
Previously unreported endocrine disrupting chemical (EDC) activity has been found in water samples from 14 states in the US. Reported by researchers at the National Cancer Institute, Maryland, USA1, the findings demonstrate the presence of androgen and glucocorticoid in US water sources. The reporting of EDCs within water sources is not new: The New York Times ran several articles on the issue in 2009–2010.2 Researchers previously focused on the identification of contaminants, whereas this new study concentrated on creating an assay for biological activity. This suggests that although levels of androgen and glucocorticoid have been previously undetected, there is a biologically relevant concentration of these chemicals.
EDCs are chemicals that alter the functioning of an organism by interfering with the endocrine (hormone) system. This has far-reaching consequences for aquatic ecosystems as well as for human health. Estrogenic compound contamination has associations with reproduction issues, cancer occurrence, obesity and thyroid metabolism to name but a few.2 The origin of ECDs in water sources is attributed to pharmaceutical waste disposal and increased use of prescription drugs by the general population. Anti-inflammatory drugs, classed as glucocorticoids, have a low recovery rate by water treatment plants and so enter water sources in the environment.
Dr Hager, co-author of the study, current analysis methods told The Column: “expensive and not applicable for large‑scale screening” with approaches focusing on the identification of specific compounds rather than activity. The use of traditional chromatographic methods and analysis can identity known chemicals within samples, but not necessarily unknown or chemicals present at low concentrations. To fill this gap in analysis, the scientists designed a living cell‑based system that could be used to process a high throughput of samples.
Androgen and glucocorticoid have a similar method of changing cell behaviour. The hormones are taken up inside the cell where they bind to their partner receptors. Once partnered, the hormones are transported to the DNA of the cell, where they alter the expression of other hormones and proteins. The scientists exploited this capability to create a reporter system. In the presence of ECDs expression of green fluorescent protein (GFP) is activated. GFP is a commonly used reporter derived from the jellyfish Aequorea victoria, which on exposure to light glows a distinctive green colour. Therefore, when the cell system was exposed to androgen or glucocorticoid, the cells glowed green.
Water samples were prepared for analysis by fractionation using high performance liquid chromatography (HPLC); subsequently, each fraction was tested using the cell-based assay. Glucocorticoid activity was found in 27% of water source samples collected from 14 US states; and androgen activity was found in 35% of the samples. Environmental degradation and metabolic processes are thought to alter the structure of known ECDs producing new bioactive structures that are not contained on any databases. This poses a potential health hazard according to the authors of the study.1
The results of the investigation may be concerning, but it is the method that offers advancements in water quality analysis. In combination with fractionation methods, would it be possible to use the cell-based assay to improve water sample analysis alongside traditional approaches? According to Hager, the answer is yes: “Our technology could provide an approach for large scale screening to investigate any potential health concern.”
1. E. Diamanti-Kandarakis et al, Endocrine Reviews 30(4), 293–342 (2012).
2. The New York Times website; Last accessed: 17th December 2012 http://projects.nytimes.com/toxic-waters