hist-brewing: Tansy in Ale

[Bryan Maloney]

>Tansy can be very dangerous in anything more than small amounts,
>especially for pregnant women.  Don't do it.

To give more detail to this warning:

There is more than one "Tansy".

_Tanacetum vulgare_ (_Chrysanthemum vulgare_) is "common tansy".  Its 
main "essential oil" is the terpenoid ketone thujone--yes, the active 
ingredient in wormwood.  Death has been known from taking common 
tansy in "medicinal" doses.  "Oil of tansy" is roughly 50% thujones, 
according to the WHO.  For dogs, LD50 occurred at 250mg/kg (oral 
administration).  However, it should be noted that Purdue University 
classifies the plant in the same category as it does common burdock, 
english ivy, and catnip.  Paulsen et al (1993), reported roughly 5% 
of test population having allergic reaction (topical) to tansy.

There is also "Tansy ragwort" (_Senecio jacobaea_).  Tansy ragwort is 
considered to be a threat to grazing livestock, able to keep its 
toxicity even after being cut and dried along with desired plants for 
use in hay.  Its dose of alkaloid toxins can kill over a long period 
of time, since the liver damage it causes can be cumulative.  The 
USDA lists it as a noxious weed, and since it's of foreign origin, 
its eradication in the USA would be legal (and highly approved of).


But even if one has a-hold of the "good" tansy, note that there are risks.

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