Temporal Variation in Multiple Hormonal Activities of Surface Waters Located in the Dutch Part of the Rhine Basin

Presently, most research in the field of endocrine disruption has focused on the estrogenic compounds. However, increasing emissions of unknown compounds into the environment may also affect other important hormone dependent processes. Recently, a suite of new sensitive bioassay techniques has become available to “look further” than estrogenic effects only. These so-called CALUX bioassays may provide a valuable contribution to the assessment of water quality. The latter is important for drinking water companies and in this context RIWA-Rhine, the Association of Water works using surface water from the Rhine river as their drinking water source, commissioned a study to utilize these new bioassays in a novel monitoring study in two important locations of the Dutch part of the Rhine basin (Lobith, Nieuwegein). The results clearly show the presence of multiple types of hormonal activity at both sample locations over the one-year sampling campaign. Estrogenic activity at both sample locations was in the same range as reported earlier and androgenic and progestagenic activities were very low. Interestingly, thyroiodogenic activity could not be detected in this study. In contrast, a previous study using a different type of assay showed potent activity at the same sampling sites. The most striking finding of the present study is the relatively high glucocorticogenic activity in water samples from both sample locations. Glucocorticoids have important physiological functions and they are applied against a great number of human diseases. A correlation with the river’s discharge was tentative, at best. Future research will be devoted to the chemical identification of glucocorticogenic compounds, a proper human health based risk assessment and a broader (tempero)spatial impression of glucocorticogenic activity in Dutch surface waters.