UV filters in Lake Geschiner

Sunscreens do not only protect us from sunburn, but also enter surface waters directly during swimming. However, some of the 30 substances that have been approved as UV filters in sunscreens can be dangerous for water organisms. The Ecotox Centre therefore advised the environmental team of the National Scouts Camp, which was held at Lake Geschiner in the summer of 2022 with more than 30,000 participants, on the measures that could be taken to reduce the risk to the small lake.

The camp also provided an ideal opportunity to measure the biological effects and environmental concentrations of UV filters in a controlled swimming environment. Therefore, in cooperation with the environmental team, water samples were taken in the lake before and during the camp. The Ecotox Centre  has investigated whether a hormonal effect caused by the UV filters can be detected, as some of them act like hormones. 

Our investigations showed that more estrogenic substances were found at the sites with bathing activity than at a control site without bathing activity. The concentration of the substances increased after the start of the camp and was higher during the camp than before. The chemical analysis of two chemical UV filters (benzophenone-3 and octocrylene) showed that they were also detected in higher concentrations after the start of the camp than before. We will have our samples analysed externally for a larger amount of UV filters.

Video on the project (in German):