Occurrence of carcinogenic illudane glycosides in drinking water wells

Background Ptaquiloside (PTA), caudatoside (CAU) and ptesculentoside (PTE) are carcinogenic illudane glycosides found in bracken ferns (Pteridium spp.) world-wide. The environmentally mobile PTA entails both acute and chronic toxicity. A comparable risk might be associated with the structurally similar CAU and PTE. It is of great health concern if these compounds are present in drinking water, however, it is currently unknown if these compounds can detected in wells in bracken-dominated regions. This study investigates the presence of PTA, CAU, PTE, and their corresponding hydrolysis products pterosins B (PtB), A (PtA) and G (PtG) in water wells in Denmark, Sweden and Spain. Water samples from a total of 77 deep groundwater wells (40-100 m) and shallow water wells (8-40 m) were collected and preserved in the field, pre-concentrated in the laboratory and analysed by liquid chromatography-mass spectrometry (LC-MS). Results Deep groundwater wells contained neither illudane glycosides nor their pterosins. However, seven private shallow wells contained at least one of the illudane glycosides and/or pterosins at concentrations up to 0.27 mu g L-1 (PTA), 0.75 mu g L-1 (CAU), 0.05 mu g L-1 (PtB), 0.03 mu g L-1 (PtA) and 0.28 mu g L-1 (PtG). This is the first finding of illudane glycosides and pterosins in drinking water wells. Conclusions Detected concentrations of illudane glycosides in some of investigated wells exceeded the suggested maximum tolerable concentrations of PTA, although they were used for drinking water purpose. Contaminated wells were shallow with neutral pH and lower electric conductivity compared to deep groundwater wells with no illudane glycosides nor pterosins.

Automated summary

The study revealed the presence of illudane glycosides and their pterosins in drinking water wells in Denmark, Sweden, and Spain. Contaminated wells were shallow with neutral pH and lower electric conductivity compared to deep groundwater wells without these compounds. Detected concentrations of illudane glycosides in some wells exceeded suggested maximum tolerable levels, raising health concerns despite their intended use for drinking water.