The naturally occurring carcinogen ptaquiloside is present in groundwater below bracken vegetation

Abstract

The present study demonstrates unequivocally the presence of the natural carcinogen ptaquiloside and its transformation product pterosin B in groundwater and surface water. Groundwater concentrations up to 0.23 nmol/L (92 ng/L) ptaquiloside and up to 2.2 nmol/L (0.47 µg/L) pterosin B were found. Of 21 groundwater samples, 5 contained ptaquiloside, exceeding the estimated threshold for drinking water (1.3-40 pmol/L). The results are critical for water abstraction in bracken-infested areas.

Ptaquiloside in Irish Bracken Ferns and Receiving Waters, with Implications for Land Managers

“…Ptaquiloside presence was recently confirmed in Danish groundwater and surface water and the risk of human exposure through consumption of shallow, untreated groundwater was highlighted [19]. In our study, ptaquiloside was observed at all three drinking water abstraction sites in October 2015.…”

“…Research underpinning quantification of ptaquiloside, and associated risk to humans and animals has expanded in the past decade, with most recent studies reporting on the fate of ptaquiloside in receiving water [19,33], animal plasma, urine and milk [34]. The proximity of bracken to drinking water supply sources and the absence of any relevant data on ptaquiloside in Ireland prompted the current investigation which has provided further evidence on the distribution of ptaquiloside in the environment.…”

“…In October 2015, the ptaquiloside concentration in bracken fronds at Doolargy (27.6 µg¨g´1) was an order of magnitude higher than at Dooghill (3.33 µg¨g´1), yet ptaquiloside concentrations in the receiving water were lower at Doolargy (0.01 µg¨L´1) than at Dooghill (0.67 µg¨L´1), which implies that the dynamics of ptaquiloside release, transport and degradation between the bracken source and water recipient, to a high extent, govern the observed concentrations. The measures of ptaquiloside in the bracken plant provide evidence that there is a significant source of ptaquiloside in the environment in Ireland, but the risk that this may pose to drinking water depends on other factors, such as soil type and proximity to the water abstraction point, and there can be significant decreases in the passing of ptaquiloside to soil layers with groundwater [19], which can be attributed to both microbial degradation and abiotic hydrolysis [37]. Dooghill was a surface water abstraction site whereas the other sites were spring wells and classed as groundwater.…”

“…The infrequency of sporulation coupled with the low content of ptaquiloside in bracken spores means that exposure of ptaquiloside through airborne bracken spores is considered insignificant [18]. Recent research indicates that drinking water abstraction in bracken infested areas is a potential concern [19]; however, there is a lack of empirical evidence to support this. In addition to toxicological effects, invasion by bracken reduces the amount and quality of land available for grazing, conservation and recreation [20].…”

Personal Care Products Are Only One of Many Exposure Routes of Natural Toxic Substances to Humans and the Environment

“…It is also used in foods and medicine, mainly in Asia, and is a known contaminant in milk produced by cows, sheep, and goats browsing on bracken [38]. There is ample evidence to show its presence in surface [39] and groundwater [40], and thus ptaquiloside may eventually contaminate drinking water (Figure 1). Although the suspected carcinogenicity of ptaquiloside has been known for a long time and there are epidemiological studies that suggest it to cause esophageal and stomach cancer in humans [41,42], there is little or no monitoring, regulation, and control of ptaquiloside in strong contrast to the regulation of, e.g., pesticides in drinking water, even though they may not be as toxic as ptaquiloside.…”