Distribution of the carcinogenic terpene ptaquiloside in bracken fronds, rhizomes (Pteridium aquilinum), and litter in Denmark.

The distribution of ptaquiloside (PTA) was studied in four Danish bracken populations in order to evaluate the transfer of PTA from ferns to soil. Populations showed statistically significant differences in PTA contents of fronds and rhizomes despite large in-site variations. The highest concentrations were encountered in fronds with concentrations ranging between 213 and 2145 microg/g, while rhizomes had concentrations between 11 and 902 microg/g. PTA was present in soil materials in amounts of 0.22-8.49 microg/g but apparently with no correlation with PTA contents of fronds or rhizomes. Laboratory tests showed that water could leach PTA from bracken fronds, which is in support of the high soil contents observed at sites exposed to heavy showers just before sampling. The observed soil contents correspond to estimated soil solution concentrations of 200-8500 microg/liter, demonstrating a substantial risk of PTA contamination of surface water and groundwater.