Harmful  Alkaliods occur naturally in many plants naturally.  Comfrey often contains harmful Alkaloids, and for this reason, is no longer recommended for consumption. (Even tho comfrey tea has been a folk medicine for a very long time, Modern herbal books no longer recommend it- tho it is still recommended for external use.  Comfrey tea and preparations from the roots are very soothing on injured or irritated skin. )
I would assume that fireweed produces these Alkaloids itself- just as comfrey does.
Ellen in Michigan
  Maurice Cobo <[log in to unmask]> wrote: --> Dr. Mohsen M. Ramadan wrote:

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-> Pollen collected from hives close to these sites should not be offered
for human consumption because of high levels of pyrrolizidine alkaloids
present in the pollen and every part of the plant (even dried parts).
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Thank you for that information, but you did not mentioned what is the source
of this agent and how it got to the vegetation.
Dr. Mohsen M. Ramadan, can you give us that information if you can ?

Thank you,

Maurice