The invasive butterbur contaminates stream and seepage water in groundwater wells with toxic pyrrolizidine alkaloids

Abstract

Pyrrolizidine alkaloids (PAs) are persistent mutagenic and carcinogenic compounds produced by many common plant species. Health authorities recommend minimising human exposure via food and medicinal products to ensure consumer health and safety. However, there is little awareness that PAs can contaminate water resources. Therefore, no regulations exist to limit PAs in drinking water. This study measured a PA base concentration of ~ 70 ng/L in stream water adjacent to an invasive PA-producing plant Petasites hybridus (Asteraceae). After intense rain the PA concentration increased tenfold. In addition, PAs measured up to 230 ng/L in seepage water from groundwater wells. The dominant PAs in both water types corresponded to the most abundant PAs in the plants (senkirkine, senecionine, senecionine N-oxide). The study presents the first discovery of persistent plant toxins in well water and their associated risks. In addition, it for the first time reports monocrotaline and monocrotaline N-oxide in Petasites sp.

Metabolic Toxification of 1,2-Unsaturated Pyrrolizidine Alkaloids Causes Human Hepatic Sinusoidal Obstruction Syndrome: The Update

“…According to a recent study in Denmark, stream and seepage water in groundwater wells can be contaminated with PAs originating from Petasites hybridus , an invasive PA-producing plant from the Asteraceae family [ 136 ]. PA values of around 0.070 μg/L were found in stream water adjacent to plant fields of Petasites hybridus and a tenfold-increased concentration following intensive rain [ 136 ]. This was associated with PA values of up to 0.230 μg/L in seepage water from groundwater wells.…”

“…This was associated with PA values of up to 0.230 μg/L in seepage water from groundwater wells. Due to little awareness on PA contamination of water resources, regulatory definitions to limit PA concentrations in drinking water are not available [ 22 , 23 , 40 , 136 ]. The reports from Denmark did not indicate whether the drinking water contaminated with PAs may have caused HSOS among individuals consuming the contaminated water, although information was provided that senkirkine, senecionine and senecione N -oxide were the predominant 1,2-unsaturated PAs found in the water [ 136 ].…”

“…On theoretical grounds, there are two conditions, whereby plants can acquire PAs: first, plants biosynthesize PAs using chemical intermediates as precursors and enzymes catalyzing the synthesis [ 24 ], and second, those plants that primarily cannot synthesize and therefore do not contain PAs may acquire PAs through soil or water contaminated with PAs [ 137 , 138 , 139 , 140 , 141 , 142 ]. Despite these promising data supporting the new concept of horizontal natural product transfer of PAs [ 137 , 138 , 139 , 140 , 141 , 142 ], a recently published study questioned the relevance of this phenomenon for PAs under field conditions [ 143 ], although many reports provided enough evidence that that horizontal tranfer is well functioning under field conditions for PAs [ 130 , 136 ] and various compounds such as heavy metals [ 144 , 145 , 146 , 147 , 148 ]. Indeed, the uptake of toxins by plants is known for heavy metals found to be severely contaminating soil, for instance, the vegetable Ipomoea aquatica consumed by nearby villagers [ 144 ].…”

Pyrrolizidine Alkaloids in the Food Chain: Is Horizontal Transfer of Natural Products of Relevance?

“…It is expected that the horizontal PA-transfer takes place via the roots; however, there seems to be the possibility that a small fraction of this transfer might occur differently. At this point in time, we assume that maybe air-borne particles (pollen or dust of the nearby L. squarrosa plants) or rainwater flowing on the soil surface and over the rims of the buried pots and carrying a PA-load from the neighboring L. squarrosa cultivation [44,45] might cause these low PA-transfers.…”

Natural toxins: environmental contaminants calling for attention

“…Little is known on toxin transfer from plant to soil; passive and active release may take place both from aboveand below-ground parts. Field studies indicate that fast and substantial release of toxins may occur during rain events generating pulses of toxins that propagates through soils to drainage and creek waters [5,28,29]. Hence, natural toxin concentrations and exposure in surface waters and in upper groundwater may be highly variable over time.…”