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Questions about Yew

BCWadell's picture

Hi,


Does anyone have any knowledge of yew?  I have a few logs with extremely interesting grain.


I checked Understanding Wood and the Wood Handbook and they don't say much.  Some online refs refer to it being poisonous.


How poisonous is it?  What kind of precautions do I need?  If I make bowls can they be handled or used to hold food?


The grain is beautiful, nice smell.  Turns well with sharp tools.


Thanks.


Brian

jonsherryl's picture

(post #82675, reply #1 of 5)

Brian, yew contains some terpenes called taxines that are cardiovascular depressants, so it is potentially dangerous. The words toxin and Taxus, which is the genus name for yew, derive from the same Latin term. The fine dust is an irritant, but there is no strong evidence that it is an allergen...It's effect on humans is universal and straight forward in that the wood's taxines, in high enough dosage, are definitely a potentially deadly poison. One historical footnote reports that some Roman soldiers died from drinking wine that had been stored in a wooden container made of yew...so, this wood has had a bad reputation for a very long time.


Yew has been used in cabinetry and for making archery bows for thousands of years, so it can be worked...but the last thing I'd consider using it for would be a food or toy related item...especially a container that might be used for storing food for any length of time or a utensil used in cooking food (like a stirring spoon) that might be left in a pot of hot stew, etc., where the toxins could be leach out quickly.   


Edited 6/8/2002 10:42:02 AM ET by Jon Arno


Edited 6/8/2002 10:43:27 AM ET by Jon Arno

BCWadell's picture

(post #82675, reply #2 of 5)

Jon,


Thanks for the info.


Any idea how toxic?  Should I worry about breathing or contacting the dust?  Can it be handled safely?  Just the usual questions you might wonder about if someone tells you a wood is poisonous ;-)


I vaguely remember a toxicity chart somewhere for various exotic woods.  I think it had some kind of scaled defined for relative toxicity, frequency of occurrence, etc.


If it's a mild irritant in woodworking and handling situations than I'll probably keep working with it.  If small amounts of dust or contact with shavings or the product can kill you then it's clearly not worth it to me.


Brian

jonsherryl's picture

(post #82675, reply #3 of 5)

Brian, if you had heart trouble and were on medication for high blood pressure, just working with yew wood might be a little dicey, but the toxins are mostly in the bark, leaves (needles) and the fruit. Eating the fruit is definitely a bad idea for anyone. For a healthy person to pick up a lethal dose from the wood, you'd probably have to concentrate the toxins by leaching them out of the wood as I described earlier...Still, a respirator would be a good precaution even when just working with the wood.


The toxin found in yew acts by slowing down the cardiovascular system...in fact, it is a potential heart medicine in measured doses, but it's potent enough that if you OD on it, it will shut your ticker down...and it IS possible to accidentally do this by allowing the wood to remain in prolonged contact with food or by eating the fruit. The wood is workable and it's been an important cabinet wood in Europe since antiquity. You just want to minimize exposure to the dust and be very careful what you make out of it, so that you don't poison yourself or someone else. 


Most woods that are known for their toxicity contain compounds that trigger allergies and the individual must have a special sensitivity to the particular allergen for the wood to be especially dangerous. In the case of yew, it contains a universal poison, meaning anyone who ingests enough of it relative to their body weight and/or the condition of their cardiovascular system is at risk. And the lethal dosage is low enough that it can be attained by using the wood in what might otherwise seem to be rather innocent applications, i.e., in association with food or drink. I guess the key point here is there's no need to be paranoid, but with yew, there definitely is a need to be careful.

BCWadell's picture

(post #82675, reply #4 of 5)

Jon,


Thanks for the detailed, authoritative responses.


(I'm not saying that's rare on these boards, but...)


Brian

StanleyNiemiec's picture

(post #82675, reply #5 of 5)

A number of years ago, a chemical compound was found in the bark of Pacific yew (Taxus brevifolia) called taxol that was found to be an effective in treating late stage ovarian, breast, lung and testicular cancers.  It was found also in the foliage and wood but the bark had the highest concentrations  --  if I rememeber correctly, somewhere about 0.5%.  The foliage contained about half that amount and wood considerably less.


For a period of a year or two, people in the PNW were running around stripping the bark from the trees and bringing it to collection centers where the Feds in conjuntion with some private chemical company were paying for it.  Things quickly got out of hand  --  people were stripping bark wherever they could find a tree  -- on federal lands (without permits), in state parks, on private land and even around peoples homes.  Some of the worst offenders would strip the bark only as far down as they were willing to bend and only as high as they were able to reach.  The wood was considered waste, and left to rot in the woods  -- and since the heartwood is extremely resistant to decay, something that will take 40 to 50 years.


Taxol is not produced by the tree itself, but rather part of some symbiotic process with a microorganism.  At present, production of taxol for medical applications is done by culturing.  While taxol is extremely toxic in small amounts (hense its effectiveness as an anti-tumor med), it can only be obtained by hot alcohol extraction.  There may be other extractives as well but taxol is the most prominent.  Sheep have been known to die after grazing on the foliage; I doubt if you will ingest that amount but I would recommend respritory protection and a good clean up after you are done.


Watch out for splinters  -- yew produces the longest, finest and sharpest slivers I have ever encountered.