Bracken fern (Pteridium aquilinum (L.) Kuhn) is a cosmopolitan plant species found on all continents except Antarctica and is considered one of the most abundant plants worldwide. It exhibits an opportunistic and invasive character, often proliferating in abandoned, newly cut, or burned areas. It is commonly found in forests, forest margins, recently deforested areas, and regressing farmland.
Bracken fern is well known for its toxic and carcinogenic properties and is one of the few known plants that can naturally induce cancer in animals. The toxic effects of bracken on livestock have been documented since the late 19th century. Consequently, bracken is listed by the WHO/IARC as a food ingredient that is possibly carcinogenic to humans. Extensive research into bracken toxins led to the isolation of ptaquiloside (PTA) in 1983 as its major, albeit unstable, toxin.
PTA is highly water-soluble and prone to leaching from topsoil into surface and groundwater. Due to potential human exposure via drinking water, PTA is considered an emerging contaminant (Skrbic et al., 2020). It hydrolyzes into the more hydrophobic pterosin B (PtB), which is considered non-toxic (Yamada et al., 2007). PtB serves as an indicator of past PTA presence and can be found in bracken plant material, soil layers, and as a hydrolysis product in water.
Recently, increasing concern over PTA contamination in drinking water has been reported in countries such as Ireland, Italy, and Denmark (O’Driscoll et al., 2016; Rasmussen et al., 2003; Zaccone et al., 2014). Currently, there are no EU regulations regarding PTA levels in drinking water. LIFE URBASO aims to monitor raw water from demonstration sites every two weeks to assess PTA and PtB levels in forested catchments supplying public water for human consumption.
References:
Skrbic, N., Pedersen, A.-K., Christensen, S. C. B., Hansen, H. C. B., & Rasmussen, L. H. (2020). A Novel Method for Determination of the Natural Toxin Ptaquiloside in Ground and Drinking Water. Water, 12(10), 2852. https://doi.org/10.3390/w12102852
O’Driscoll, C., Ramwell, C., Harhen, B., Morrison, L., Clauson-Kaas, F., Hansen, H. C. B., Campbell, G., Sheahan, J., Misstear, B., & Xiao, L. (2016). Ptaquiloside in Irish Bracken Ferns and Receiving Waters, with Implications for Land Managers. Molecules, 21(5), 543. https://doi.org/10.3390/molecules21050543
Yamada, K.; Ojika, M.; Kigoshi, H. (2007). Ptaquiloside, the major toxin of bracken, and related terpene glycosides: Chemistry, biology and ecology. Nat. Prod. Rep., 24, 798–813. https://doi.org/10.1039/b614160a
Rasmussen LH, Kroghsbo S, Frisvad JC, Hansen HC. (2003) Occurrence of the carcinogenic Bracken constituent ptaquiloside in fronds, topsoils and organic soil layers in Denmark. Chemosphere ;51(2):117-27. https://doi.org/10.1016/s0045-6535(02)00694-x
Zaccone C, Cavoski I, Costi R, Sarais G, Caboni P, Traversa A, Miano TM. (2014) Ptaquiloside in Pteridium aquilinum subsp. aquilinum and corresponding soils from the South of Italy: influence of physical and chemical features of soils on its occurrence. Sci Total Environ. 15;496:365-372. https://doi.org/10.1016/j.scitotenv.2014.07.046
