Talk:Jacobaea vulgaris

Scottish origin

hi MPF,

My source for teh scottish origin was http://www.crescentbloom.com/Plants/Specimen/SE/Senecio%20jacobaea.htm which generally I found a reliable source.

What source do you have for removing it? TeunSpaans 19:04, 15 Oct 2004 (UTC)

On second thoughts, I tend to agree that it does sound unlikely. TeunSpaans 19:14, 15 Oct 2004 (UTC)

Height of Tansy Ragwort

I changed the maximum height of Tansy Ragwort to 2 meters. I am the manager of a noxious weed control program on the west coast of Canada and we commonly find plants growing to 2+ meters in height. — Preceding unsigned comment added by 207.194.58.93 (talk • contribs)

I can support this also for the UK. I am the Research manager for Ragwort-UK ltd and have frequently recorded plants over 2m tall growing in fertile land with good water supply. These are not rare strains of ragwort, any plant can reach these proportions if given the right conditions. These giants typically have ca 12 major stems originating from the crown and the total seed production has been estimated to be in excess of 2 million seeds for the whole plant. -- DerekSmith

I have removed the following paragraph.

Since 1996, the population of Ragwort in the UK has substantially increased due to Wolf-Sheep Predation Dynamics and 1988 success of Ragwort's only major predator, the Cinnabar Moth.

The population of ragwort has continued to grow since the early nineties and is now becoming a problem for animals. Ragwort is highly toxic to animals. Usually horses are able to discriminate the ragwort, see Poisonous effects. Horses have eaten it in hay, or ironically after it has been cut down after trying to protect the horses.

— Preceding unsigned comment added by Neilj (talk • contribs)

There is someone who is trying to promote the idea that the cinnabar moth has undergone a population crash in the UK and that consequently a plague of ragwort has ensued as it supports the sale of the moths as a biological control. It has got repeated many times as a result of a marketing campaign. However, as any competent British entomologist ( insect specialist) will tell you, this is not so. The moth has remained common and whilst in common with most British moths a decline in numbers can be shown statistically there is no known correlation with any increase generally in the ragwort population.

Ragwort has not increased either. There is no plague. The remainder of the paragraph simply repeats information that is better covered elsewhere in the article, therefore I deleted it.

-- Neilj

Neilj, you have a contradiction. In one sentence you state that there is no decline in Cinnabar numbers, yet in the next sentence you state that the Cinnabar along with all other British moths is in in decline. Your contradiction destroys the validity of your argument.

You then go on to state that ragwort is not on the increase, yet you offer no proof of your opinion. I on the other hand have factual audit data which I am prepared to provide to the Wikepedia admins to prove that ragwort is significantly on the increase in land where its presence is not being managed.

-- DerekSmith —Preceding unsigned comment added by DerekSmith (talk • contribs) 15:41, 22 September 2007 (UTC)

Too many red links!

Self-explanatory. Bibliomaniac15 00:51, 15 March 2006 (UTC)

removed a link ragwortfacts, cause that link is have to many unproven suggestions, ans the website forget to look at the primary literature where th WHO report points. —Preceding unsigned comment added by Falka (talk • contribs) 10:12, 20 September 2007 (UTC)

I think the other changes introduced by that last group of edits sound very POV and tend to promote the individual's business more than I think is acceptable. I also notice Googling around that a commercial website run by the same editor contains the same statement that Neilj removed from the article before as a central marketing theme. I am relatively new to this editing business as I think as we have some obviously expert naturalists (looking at the names) that I will leave it to you people to handle for now but we need some better sources for one or two things in the article particularly toxicity. —Preceding unsigned comment added by LadyGlanville (talk • contribs) 13:34, 20 September 2007 (UTC)

I agree, I removed the worst statements about the PAs and poisoning, and will take a better look at it to explain how the PAs work. I had a closer look at the website I removed and I saw a lot of speculations with no scientific evidence. Maybe somebody can put the old version back? Falka 16:39, 20 September 2007 (UTC)Falka

I must disagree with the edits by Falka. You removed 'highly' toxic. The who stated that 15ppb/kg/day caused VOD -- a generally fatal condition from 15ppb/kg/day is regarded as highly toxic. You removed the advice that horses will eat live seadling ragwort despite the fact that there is documented evidence that this occurs whenever seedling ragwort is present in equine grazing -- horses cannot taste seedling ragwort and graze it with the grass. If you wish to remove this then please offer proof that this is not the case to counter the documented proof that it is. Yes Ragwort-Uk is a commercial operation but the url you deleted is to an information only site and makes no sales claims at all. Furthermore the site makes statements based heavily on the WHO document EHC80 already cited. Finally, you claim that there is no increase in ragwort distribution. Please publish your data to prove this. Ragwort-UK do annual surveys and have data to support the claims that ragwort continues to claim more land each year and increase its density each year in areas that are not under rigorous ragwort control management. The WHO make clear warning of the dangers of allowing PA rich plants to proliferate. Ragwort proliferation is an issue of public safety and the onus of disproving the WHO position is upon you to disprove their position which is clearly stated in EHC 80

There remain further errors in the section on toxity. I will correct these in line with the facts published by the WHO in EHC80

DerekSmith Research Manager Ragwort-UK Ltd —Preceding unsigned comment added by DerekSmith (talk • contribs) 22:54, 21 September 2007 (UTC)

Derek Smit I have to disagree with you, the website I removed is not objective. I miss scientific evidence about that skin absorption you suggest on that website. Maybe you can proof that with scientifical literature. It is not nescesary to scare people. Then you point to eating seedlings. All the scientific literature describes when horses eat fresh ragwort it is rare or they are forced to eat it cause they are starving. ( European Food Safety Authority. 2007. Opinion of the Scientific Panel on contaminants in the food chain on a request from the European Commission related to Pyrrolizidine alkaloids as undesirable substances in animal feed. The EFSA Journal 447: 1-51. Cosyns, E. 2004. Ungulate seed dispersal. Aspects of endozoochory in a semi-natural landscape. Institute of Nature Conservation, Brussels). And a lot more literature.But although every bite of Ragwort may cause liver cells to die, this doesn’t mean that eating a bite of Ragwort once in a while has a lasting effect on an animal’s health. This is because, up to a certain extent, healthy liver cells take over the function of damaged liver cells

You can compare it more or less with drinking a glass of beer once in a while. Drinking alcohol kills liver cells, but if you don’t regularly drink large amounts of alcohol, it won’t have a lasting impact on your health. Look at this webpage there are many sources and explanation. http://www.ragwort.jakobskruiskruid.com/Myths%20and%20Facts/Ragwort%20poisoning%20How%20does%20it%20work.html If you really understand how PAs work you have to know that. Yes it is true PAs are poisonous to human, but you forget to point at the primary literature of the WHO report that tells about the circumstances and how it can happen. In the meanwhile there is a law in Europe about herbal medication and PAs. Ragwort is not a hazard for public safety in Europe. European Food Safety Authority. 2007. Then you claim that ragwort is cultivated by Ragwort-UK Ltd.

Falka 14:26, 22 September 2007 (UTC)

Falka, thank you for trying to understand this situation and explaining to me your understanding and giving me the source of that understanding. Sadly, both you and your quoted source are in complete disagreement with the findings of the dozen or so Professors and Doctors who undertook a full review of literature and data from around the world in the preparation of the report "Pyrrolizidine Alkaloids" Environmental Health Criteria 80 1988 -- ISBN 92 4 154280 2 This report was commisioned by the World Health Organisation, The United Nations Environment Programme and the International Labour Organisation. I hope that you would agree that a document promoted by the WHO carries far greater credibility than the website you have proposed we believe, particularly when the information contained on that site is so at odds with the data presented in the WHO report.

The WHO report is 345 pages of concentrated scientific information, (with the exception of a few pages of Summary and Recommendations written for understanding by non chemists/medical professional). It is obvious from your comments that you have either not taken the somewhat significant amount of time necessary to read this reference work or you have not understood what you have read. This to a degree is understandable as to digest this work requires a significant contribution of time and at least a moderate grounding in chemistry and biological reactions.

You state that you "miss scientific evidence about that skin absorption you suggest on that website". Yes you clearly did. If you care to read section 4 METABOLISM, sub section 4.1.1 Absorption -- you will see that a number of studies are reported and that skin absorption is demonstrated. On the basis of this evidence, for our Operational Risk Assessment for employees working with ragwort, we have been advised by the Health & Safety Executive to take all parts of the ragwort plant to be hazardous and to treat skin adsorption and inhalation as major occupational safety issues along with accidental ingestion.

Another aspect of your reply which indicates that you have not read or perhaps more importantly, not understood the EHC 80 report is your (and the authors of jakobskruiskruid website) fictional perception of the mode of action of PAs. PAs are not toxic !! PAs are enzymatically converted into pyrrolic derivatives which are highly reactive and hepatotoxic. Could I suggest that you read carefully section 4 for the facts as the WHO states them.

One important distinction which you should easily note is that ragwort poisoning is not in any way like the damage caused to the liver by drinking of alcohol. The pyrrolic derivatives are persistent and cause repeated and continuous destruction of hepatocytes. A single ingestion can lead to continued liver destruction and eventually lead to death 18 to 24 months after the ingestion. Please read this document (EHC 80). You may not like what you read but it is important that you do not support and regurgitate misinformation when health and lives are at risk, particularly when the facts have been carefully validated and published by the WHO for your education.

DerekSmith 08:46, 24 September 2007 (UTC)DerekSmith —Preceding unsigned comment added by DerekSmith (talk • contribs) 17:07, 22 September 2007 (UTC)

Derek Smith I still disagree with you. Maybe maybe you didn t read the references I gave you before, it is really recent and written by the scientific panel of the EU. This report goes a lot more information about health hazards for animals and people. They studied a lot of literature, even the sources from the WHO report. We know that Pas are not toxic in their N Oxide, we explain that on the website also. The website is written and advised by specialists. I know the WHO report very well,and that is why I disagree with you You point to 4 METABOLISM, sub section 4.1.1 Absorption. In that section the WHO report refers to Brauchli J., J. Luthy, U. Zweifel & C. Schlatter. 1982. Pyrrolizidine alkaloids from Symphytum officinale L. and their percutaneous absorption in rats. Experientia (Basel) 38: 1085-1087. We studied these primary papers.

These scientists state that toxicological research on rats has proved that the pyrrolizidine alkaloids from the roots of comfrey (Symphytum officinale, Borganinaceae) can be absorbed through the skin. However, the amount of absorbed pyrrolizidine alkaloids appears to be much lower than when they where administered orally. The amount of pyrrolizidine alkaloids found in the urine of the rats was 20 to 50 times less than was measured when it was given orally. As long as the plant has not been eaten the pyrrolizidine alkaloids are in a N-oxide form and are not poisonous. When the plant is eaten they are transformed, mostly in the small intestine, into free alkaloids that are poisonous and that will damage the liver. The treatise of Brauchli and colleagues (1984) states that pyrrolizidine alkaloids that are absorbed through the skin are rarely, if ever, transformed into free alkaloids. Through our research about the sources of the reports on the danger of touching ragwort, we conclude that there is no substantial evidence that there is a health risk for people. The amount of pyrrolizidine alkaloids that might be absorbed through the skin is very low and there is no proof that these alkaloids are being changed into a toxic form. Then the WHO report section 5.1.1 Metabolic basis of toxicity

Direct application of these alkaloids to the skin does not cause local toxic effects (Schoental et al., 1954), nor do cytotoxic effects occur at sites of injection.

About the reactive pyrroles You state A single ingestion can lead to continued liver destruction and eventually lead to death 18 to 24 months after the ingestion. It is true Pas can have a cumulative effect, according to the literature, a diet consisting of 1-2% Ragwort can be lethal in time ( Molyneux et al, Goeger et al) The more recent link I gave you before Tells about ingestion PAs are eliminated very rapidly. In a study conducted by Williams et al. (2002), the elimination half-life for riddelliine in rats and mice was 4.2 and about 3 hours, respectively. Riddelliine-Noxide was eliminated more slowly, with half-life’s ranging from 7 to 12 hours in rats (male versus female) and 15 to 29 hours in mice (male versus female). In a study, conducted by Eastman et al. (1982) on the kinetics of senecionine and seneciphylline in lactating mice, 89h% and 84 % of the administered doses of senecionine and seneciphylline were eliminated 16 hours after their administration.

The main route of elimination is via the urine, mainly in the form of the parent alkaloid and a small amount in the form of the corresponding N-oxide. A smaller fraction is eliminated in the bile. The bile contains mostly reactive pyrroles and their associated products (Estep et al., 1991). A small portion of senecionine and seneciphylline was found to be eliminated via the respiratory tract (McLean, 1970; Eastman, 1982; Estep et al., 1991) Pyrrolizidine alkaloids (PAs) represent a large group of chemically diverse plant metabolites that share essentially the four necine bases platynecine, retronecine, heliotridine and otonecine. Most of the naturally occurring PAs are esters or N-oxides of these necine bases and more than 6000 plants have been identified as potential sources of PAs,

And about the liver some interesting stuff to read there is some about the time and doses from eating, it is not one bite and when animals stop ingesting it is possible to recover.

• Czaja, M. 1998. Liver growth and repair. Chapman en Hall London. ISBN 0412 71260
• Craig, A. M., E. G. Pearson, C. Meyer & J. A. Schmitz. 1991. Serum liver enzyme and histopathologic changes in calves with chronic and chronic-delayed Senecio jacobaea toxicosis. Am. J. Vet. Res. 52: 1969-1978
• Gardner, D. R., M. S. Thorne, R. J. Molyneux, J. A. Pfister & A. A. Seawrigh. 2006. Pyrrolizidine alkaloids in Senecio madagascariensis from Australia and Hawaii and assessment of possible livestock poisoning. Biochemical Systematics and Ecology 34: 736-744
• Lessard, P., W. D. Wilson, H. J. Olander, Q. R. Rogers, & V. E. Mendel. 1986. Clinicopathologic study of horses surviving pyrrolizidine alkaloid (Senecio vulgaris) toxicosis. Am. J. Vet. Res. 47: 1776-1780.
• Molyneux R. J., Johnson, A. E.& L. D. Stuart. 1988. Delayed manifestation of Senecio-induced pyrrolizidine alkaloidosis in cattle: case reports. Vet. Hum. Toxicol. 30: 201-205.
• Goeger, D. E., P. R. Cheeke, J. A. Schmitz & D. R. Buhler. 1982. Toxicity of tansy ragwort (Senecio jacobaea) to goats. Am. J. Vet. Res. 43: 252-254.
• De Lanux-Van Gorder, V. 2000. Tansy ragwort poisoning in a horse in southern Ontario. Can. Vet. J. 41: 409-410.

Enough for now I think. Falka 06:12, 23 September 2007 (UTC)

Falca, before I respond to your considerable response, could I please confirm that I have read the correct reference which you say was written by the scientific panel for the EU. The link I followed in your text led me to a site called ragwort.jakobskruiskruid.com and claims to have been authored by By: Esther Hegt and Pieter B. Pelser (Miami University - Botany department, Oxford, Ohio, USA)

Are you claiming that these authors are the scientific panel for the EU? or have I read the wrong site?

DerekSmith —Preceding unsigned comment added by DerekSmith (talk • contribs) 19:05, 23 September 2007 (UTC)

Derek Smith I think you mix things. The site I mentioned is written by experts. Indeed Esther Hegt( that is me) and Pieter Pelser and there are a lot of other advisors to. Each webpage give a list of referense of the studied literature. All the names of the experts are called on that website under the page authors and advisors.

The scienitific panel of the EU report is written by other scientists, (I some know personally from advices they gave me) is this one ( European Food Safety Authority. 2007. Opinion of the Scientific Panel on contaminants in the food chain on a request from the European Commission related to Pyrrolizidine alkaloids as undesirable substances in animal feed. The EFSA Journal 447

Falka 19:20, 23 September 2007 (UTC)

Thank you Esther for clarifying your position for me. It is always important to be sure of our understanding and our facts when communicating with someone who is using a second language.

You are working with a number of false understandings which are in conflict with the facts published by the WHO in EHC 80. If you will permit me, it will be my pleasure to assist you to understand the information published within that report. None of the information I have quoted is mine, nor is it in any way my opinion, I am simply quoting the facts reported within the EHC 80 by the 13 internationally reputed scientists who prepared it and the WHO who have ratified and published it.

The first thing you must understand is that Pyrrolizidine Alkaloids are not toxins, they are precursor toxins and only become toxins when metabolised by liver enzymes into "pyrrolic dehydro-alkaloids which are reactive alkylating agents" (EHC 80 1.3). From this you must understand that PAs are not toxic in any stage within the body, neither during ingestion, nor during skin absorption, nor inhalation, nor excretion. They pass unreacted around the body in the blood stream and do no harm and the great majority of PAs are excreted harmlessly in the animals urine, or if it is lactating, into its milk. This is why in section 5.1 of EHC 80, it is stated that "Direct application of these alkaloids to the skin does not cause local toxic effects". The important word in this sentence is 'local'. The PAs do not cause local poisoning because PAs are not poisonous. It is not until they have passed into the bloodstream and thus into the liver that they are metabolised into cytotoxic pyrrolic derivatives. Poisoning then happens in the liver -- not at the local point of absorption of the non toxic PA. I hope you see now how you have confused the meaning of the statement in 5.1.

Second, you must realise that according to the WHO, PAs are metabolised into toxic pyrrolic derivatives in the liver, not in the small intestine as you have claimed earlier. This is very clearly stated in the first para section 1.3 of EHC 80 vis - "The toxic effects of pyrrolizidine alkaloids are due to activation in the liver". The highly reactive derivatives (toxins) then rapidly attack the the nearest cells i.e. the liver cells. The metabolising enzymes are not present in any other tissues, therefore only the liver, rich in the mixed function oxidases, is capable of converting the PAs and the liver is the primary organ suffering the cytotoxic attack.

Third, you must understand the difference between long term repeated ingestion and persistent toxification in order to understand why ragwort poisoning is not like alcohol (from which the liver can recover). You stated that you understood that repeated ingestion of small amounts [as little as 0.015mg/kg/day] of PAs can lead to liver disease - this is correct. However, one dose of PAs can form derivatives which continue to damage the liver for many months. The cytotoxic derivatives are not flushed out of the system as the unmetabolised PAs are. The derivatives are persistent and continue to destroy liver cells without any further ingestion of PAs. Please carefully study section 7 Effects on Man, particularly Fig. 12 P 180 EHC 80 and you will see that death can follow months or years after exposure has ceased, from either VOD or cirrhosis.

I hope that you are now starting to understand the reality of ragwort poisoning as published and endorsed by the WHO. I am sure that sufficient detail has now been discussed such that a layperson will understand the situation and that the Wikepedia Moderators will be able to make a fully informed decision should the issue come to require moderator intervention.

DerekSmith 08:46, 24 September 2007 (UTC)DerekSmith

I have removed the edits performed by user DerekSmith. I believe that they go beyond what is acceptable. Mr Smith has a strong conflict of interest and he has both inserted a website link and test that promote that interest even mentioning his company name whilst doing so. Mr Smith's business depends on the public believing that Ragwort is highly toxic so that they will buy his product.

It is also the case that his business's primary website is selling Cinnabar moths using a story which has been explained to be false above, and which I as a bug person concur with. There are many other errors on the sites and the site linked to could even be legally dangerous to Wikipedia. I would caution us all to be aware of conflicts of interest which may affect our judgement.

One specific comment I would deal with this is about the persistance of toxins. I believe the WHO report has been tendentiously used to argue a case and that that in the argument above too much emphasis has been laid on items that refer to other plants not ragwort where there is a danger that does not exist in ragwort and that the report has not been read in its entirety and that a biased conclusion has been drawn. For example the toxins DO NOT persist

"To summarize, the available evidence suggests that ingested

   toxic pyrrolizidine alkaloids are rapidly metabolized and that the 
   excretion of unchanged alkaloid and of most metabolites is also 
   rapid.  Thus, within a few hours, only a relatively small 
   proportion of the dose remains in the body, much of this in the 
   form of metabolites bound to tissue constituents.  It appears 
   improbable that a significant amount of unchanged alkaloid will
    remain in the body after the first day."

Sorry I forgot to sign the above comment LadyGlanville

I agree very much. Those edits do go against the conflict of interest policies and the commercial point of view

pushing isn't acceptable on Wikipedia. The justifications posted above are very tendentious and has just been shown very easily refuted. I also agree about the cinnabar moths. If you tell an entomologist that there is a plague of ragwort because cinnabar moths nearly vanished, they laugh. ( No intention to offend but it is that strange an idea.) Neilj

if the toxins persist it is a piece of cake to proove a ragwort poisoning.

A single disgestion leading to death sounds like witchcraft. Derek Smit you tell this "PAs are metabolised into toxic pyrrolic derivatives in the liver, not in the small intestine as you have claimed earlier " I suggest you read carefully this page http://www.ragwort.jakobskruiskruid.com/Myths%20and%20Facts/Pyrrolizidine%20alkaloid%20metabolism.html references (Chojkier, M. 2003. Hepatic sinusoidal-obstruction syndrome: toxicity of pyrrolizidine alkaloids. Journal of Hepatology 39: 437-446) .and (Fu, P. P., Q. Xia, G. Lin & M. W. Chou. 2004. Pyrrolizidine alkaloids - Genotoxicity, metabolism enzymes, metabolic activation, and mechanisms. Drug Metabolism Reviews 36: 1-55). You can see the metabolism start in the intestines. Because these intermediate molecules are quickly transferred into other molecules, they cannot be found in samples taken from an animal. Only the presence of dehydro-PAs can be shown. Although these dehydro-PAs are more stable than the molecules that are formed in the process in which N-oxides are transferred into dehydro-PA's, they can also react with a lot of other molecules. When an animal stops ingesting ragwort this molecule is also not traceble.

Falka 19:22, 24 September 2007 (UTC)

the correct scientifical name

The correct name is Jacobaea vulgaris I don't know how to change it correct in Wiki. The primary source for the new name Pelser, P. B., Gravendeel, B. & van der Meijden, R., (2002). Tackling speciose genera: species composition and phylogenetic position of Senecio sect. Jacobaea (Asteraceae) based on plastid and nrDNA sequences. Am.J.Bot. 89(6): 929-939 Pelser, P.B., Veldkamp, J.-F. & van der Meijden, R., (2006). New combinations in Jacobaea Mill. (Asteraceae - Senecioneae). Compositae Newsletter 44: 1-11. —Preceding unsigned comment added by Falka (talk • contribs) 21:30, 13 March 2008 (UTC)

Requested move

The following discussion is an archived discussion of a requested move. Please do not modify it. Subsequent comments should be made in a new section on the talk page. Editors desiring to contest the closing decision should consider a move review. No further edits should be made to this section.

The result of the move request was: no consensus. Jenks24 (talk) 15:25, 28 August 2012 (UTC)

---

Jacobaea vulgaris → Senecio jacobaea – This plant is generally known scientifically as Senecio jacobaea, including in the most up-to-date and widely used European flora by Clive Stace ([1]). I can't find any up-to-date use of the name currently used in the article (Jacobaea vulgaris). Richard New Forest (talk) 10:02, 11 August 2012 (UTC)

USDA GRIN has is as Jacobaea vulgaris. The Plant List has both names as accepted, and Tropicos agrees with you. This is quite strange, all of these databases are very good. GRIN specifies that they are homotypic synonyms, and IPNI says that Linnaeus' Senecio name has been replaced by the Jacobaea name.

So in short, the databases are no help.

Scholarly articles are also divided, e.g., here and here.

Wikipedia follows other authorities, it doesn't make up its own mind. I think, therefore, that it is best to leave the status quo, that it is premature to change without a clear consensus from these experts. Sminthopsis84 (talk) 21:26, 11 August 2012 (UTC)

The above discussion is preserved as an archive of a requested move. Please do not modify it. Subsequent comments should be made in a new section on this talk page or in a move review. No further edits should be made to this section.

Scientific names

I went to check the relative commonness of Jacobaea vulgaris vs Senecio jacobaea in Google's ngram viewer, and found that the former doesn't get any hits (which is surprising, because if one performs a regular Google Books search for it, it does get hits). -sche (talk) 18:55, 11 September 2013 (UTC)

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reference dump

• Joosten, Lotte; Mulder, Patrick P. J; Vrieling, Klaas; Van Veen, Johannes A; Klinkhamer, Peter G. L (2009). "The analysis of pyrrolizidine alkaloids in Jacobaea vulgaris; a comparison of extraction and detection methods". Phytochemical Analysis: n/a. doi:10.1002/pca.1183.
• Boppré, Michael (2011). "The ecological context of pyrrolizidine alkaloids in food, feed and forage: An overview". Food Additives & Contaminants: Part A. 28 (3): 260. doi:10.1080/19440049.2011.555085.
• Wiedenfeld, Helmut; Edgar, John (2010). "Toxicity of pyrrolizidine alkaloids to humans and ruminants". Phytochemistry Reviews. 10: 137. doi:10.1007/s11101-010-9174-0.
• Segall, H (1978). "Pyrrolizidine alkaloids derived from Senecio jacobaea". Toxicology Letters. 1 (5–6): 279. doi:10.1016/0378-4274(78)90007-3.
• Edgar, John A; Roeder, Erhard; Molyneux, Russell J (2002). "Honey from Plants Containing Pyrrolizidine Alkaloids:  A Potential Threat to Health". Journal of Agricultural and Food Chemistry. 50 (10): 2719. doi:10.1021/jf0114482. PMID 11982390.
• . doi:10.1016/j.yrtph.2015.09.024. {{cite journal}}: Cite journal requires |journal= (help); Missing or empty |title= (help)
• Edgar, John A; Roeder, Erhard; Molyneux, Russell J (2002). "Honey from Plants Containing Pyrrolizidine Alkaloids:  A Potential Threat to Health". Journal of Agricultural and Food Chemistry. 50 (10): 2719. doi:10.1021/jf0114482. PMID 11982390.
• Kempf, Michael; Reinhard, Annika; Beuerle, Till (2010). "Pyrrolizidine alkaloids (PAs) in honey and pollen-legal regulation of PA levels in food and animal feed required". Molecular Nutrition & Food Research. 54: 158. doi:10.1002/mnfr.200900529.

• Cortinovis, Cristina; Caloni, Francesca (2015). "Alkaloid-Containing Plants Poisonous to Cattle and Horses in Europe". Toxins. 7 (12): 5301. doi:10.3390/toxins7124884. PMID 26670251.{{cite journal}}: CS1 maint: unflagged free DOI (link)

• Kempf, M; Wittig, M; Reinhard, A; von Der Ohe, K; Blacquière, T; Raezke, K.-P; Michel, R; Schreier, P; Beuerle, T (2011). "Pyrrolizidine alkaloids in honey: Comparison of analytical methods". Food Additives & Contaminants: Part A. 28 (3): 332. doi:10.1080/19440049.2010.521772.

• Giles, C. J (1983). "Outbreak of ragwort (Senecio jacobea) poisoning in horses". Equine Veterinary Journal. 15 (3): 248–50. doi:10.1111/j.2042-3306.1983.tb01781.x. PMID 6136403.

• Hoogenboom, L.A.P; Mulder, P.P.J; Zeilmaker, M.J; Van Den Top, H.J; Remmelink, G.J; Brandon, E.F.A; Klijnstra, M; Meijer, G.A.L; Schothorst, R; Van Egmond, H.P (2011). "Carry-over of pyrrolizidine alkaloids from feed to milk in dairy cows". Food Additives & Contaminants: Part A. 28 (3): 359. doi:10.1080/19440049.2010.547521.

• Wiedenfeld, H (2011). "Plants containing pyrrolizidine alkaloids: Toxicity and problems". Food Additives & Contaminants: Part A. 28 (3): 282. doi:10.1080/19440049.2010.541288.

• Leiss, Kirsten A; Choi, Young H; Abdel-Farid, Ibrahim B; Verpoorte, Robert; Klinkhamer, Peter G. L (2009). "NMR Metabolomics of Thrips (Frankliniella occidentalis) Resistance in Senecio Hybrids". Journal of Chemical Ecology. 35 (2): 219. doi:10.1007/s10886-008-9586-0. PMID 19169751.

• Leiss, Kirsten A (2010). "Management practices for control of ragwort species". Phytochemistry Reviews. 10 (1): 153–163. doi:10.1007/s11101-010-9173-1. PMC 3047715. PMID 21475410.

• Roberts, P.D; Pullin, A.S (2007). "The Effectiveness of Management Interventions Used to Control Ragwort Species". Environmental Management. 39 (5): 691. doi:10.1007/s00267-006-0039-7. PMID 17377727.

• Wiedenfeld, H (2011). "Plants containing pyrrolizidine alkaloids: Toxicity and problems". Food Additives & Contaminants: Part A. 28 (3): 282. doi:10.1080/19440049.2010.541288.

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Reason why the website ‘Ragwort Facts’ is not a reliable source of evidence

The website ‘Ragwort Facts’ claims to give ‘A UK Scientific Perspective’ on ragwort in the UK. However, the website does not observe proper scientific standards of objectivity. The author of the website, Neil Jones, claims to be a ‘scientifically minded person who loves reason and the study of scientific learning’ but gives no evidence of his scientific qualifications. The ‘Ragwort Facts’ website has not been independently reviewed or refereed therefore its scientific credibility rests entirely on the reputation and scientific credibility of the author, which, in this case, cannot be established. Even a cursory reading shows that the website is highly partisan and devoted to arguments that tend to represent ragwort as relatively benign and harmless to animals. Two examples will suffice:

First. The author claims that The British Horse Society falsely claimed in a 2014 survey that "ragwort is extremely toxic to horses." His argument is that “There is a definition that is used by scientists to identify substances that are "extremely toxic" and it is defined as something where 5 miligrams per a kilogram of body weight or less is lethal. There are one million milligrams in a kilogram so we can say that something that is "extremely toxic" is a substance where 5 millionths of the animal's weight (or less) being ingested is likely to kill it. The reality is that the lethal dose is much closer to 5 percent of the body weight. This is 5 parts in a hundred. This means that the British Horse Society is over estimating the toxicity of ragwort by around the order of ten thousand times!” This is an unscientific argument because the BHS is referring to fresh or dried ragwort whereas, presumably, the scientific definition of toxicity refers to the actual toxins contained in the ragwort, pyrrolizidine alkaloids. The BHS statement is based on a common language definition of toxicity and refers to actual plant consumption by animals whereas the scientific definition of toxicity is based on extracted and purified pyrrolizidine alkaloids. This argument confounds a comparison of the toxic effects of whole plant material with the toxic effects of the purified alkaloid toxin solely to make the spurious claim that the BHS over-estimates the toxicity of ragwort by around the order of ten thousand times. This is a deliberate attempt to mislead and is clearly intended to give the false impression that the toxicity of ragwort is somehow ten thousand times less serious than is generally thought.

Second. The author claims that ‘Ragwort poses no risk to dogs’ and says that dogs do not eat ragwort. This claim is false as all dogs will eat a certain amount of green plant material from time to time, including ragwort (personal observation). The toxic component of ragwort is highly toxic to all mammals, including dogs, therefore, under appropriate circumstances, ragwort can be a serious risk to companion animals. There appears to be little information in the scientific literature about the toxicity of ragwort in dogs but the Dogs Trust list of poisonous plants states that ragwort: ‘Causes kidney failure and liver damage which is irreversible. Minute doses fatal, often wrongly diagnosed’ (i). The known susceptibility of dogs to poisons generally and the likely lack of any natural protective mechanisms against plant toxins is supportive of the Dogs Trust therefore, the claim that ‘Ragwort poses no risk to dogs’ is both irresponsible and dangerous.

Conclusion The ‘Ragwort Facts’ website, far from presenting an objective scientific perspective on ragwort, presents a highly partisan views by a committed entomologist. As illustrated by the two examples, the website gives a highly subjective and misleading view of the evidence and deliberately downplays the dangers of ragwort to livestock and other animals. This website contains much misinformation and is not suitable to be referenced by Wikipedia as a source of objective scientific information. https://www.cdts.co.uk/wp-content/uploads/2017/02/POISONOUS-SUBSTANCES.pdf NameArbitrary (talk) 11:05, 9 June 2023 (UTC)

This looks as a rant to me, I looked at ragwort facts and the evidence is clear, the sources are named, so everybody can look if the statements are true, there are peer reviewed published sources on ragwort facts website. There isn't peer reviewed literature abut poisonous for dogs. Dogs don't eat hay and have a different dieet. The PDF sheet as you have added is not peer reviewed literature. It is only a rant, stop with that. Falka (talk) 07:52, 4 July 2023 (UTC)

The ‘Ragworts Facts’ site does not present objective scientific arguments and is very far from ‘clear’. It views ragwort from an entomological point of view and uses ‘evidence’ in an extremely selective and cavalier fashion, which certainly would not pass an authoritative scientific review.

It makes statements like:  

FALSE . This claim was made by the British Horse Society in a survey in 2014. It over estimates the toxicity of ragwort by around TEN THOUSAND TIMES! See Ragwort is not extremely toxic

This is absurd and is not made OK by saying that ‘everybody can look if the statements are true’.  

‘Dogs don't eat hay’ and ‘Ragwort is as dangerous to dogs as it is to dolphins’ (see Ragworts Facts) are absurd statements. Dogs and other companion animals frequently eat green plant material and there are many, many cases of companion animal poisonings each year due to ingesting poisonous plants. Unfortunately, it is often extremely difficult to identify the source of a plant poison.

The PDF information sheet that I added was produced by the Dogs Trust which is one of the oldest and biggest and most highly respected dog charities in the world with a large professional staff including veterinarians. If you choose to regard this as a ‘rant’ that is your concern but I prefer to regard it as the informed view of an organization with access to direct up-to-date information about animal poisoning. NameArbitrary (talk) 10:55, 4 July 2023 (UTC)

User:FalkaThe claim that ragwort is toxic to dogs is basically correct. After all, it is poisonous to all animal species, including humans. The question is whether a dog can ingest enough plant material to become acutely ill. I don't know any examples of that either. It also seems unlikely to me because PAs are not fast-acting toxins, unlike many other toxic plant compounds that act directly on the nervous system, heart or intestines. Unless a dog eats whole ragwort plants (and doesn't vomit them right away), the chance of poisoning is estimated to be low. There is no need the remove the link Ragwort Facts, it looks like a personal vendetta because there is also a contact email adres on the website ragwort facts . Don't use wikipidea for vendetta's User:Falka — Preceding undated comment added 08:20, 6 July 2023 (UTC)