There is a detailed article in German with more information: https://www.spektrum.de/news/klarspueler-gefahr-fuer-die-darmgesundheit-oder-falscher-alarm/211523

There is a detailed article in German with more information: https://www.spektrum.de/news/klarspueler-gefahr-fuer-die-darmgesundheit-oder-falscher-alarm/2115231 https://www.spektrum.de/news/klarspueler-gefahr-fuer-die-dar... Overall, this sounds like the danger is rather low.