Absorption of arsenic by edible plants

Chris Owens caowens at redsuspenders.com
Wed Mar 22 17:49:40 EST 2000

"A. M. Hawk Widner" wrote:
> There are two schools of thought on that.  One school declares that nothing
> edible should be planted near the wood at all, in fact it should not be used
> for anything at all.  The other school is that it is probably relatively
> safe.  One of this latter group actually posted in here once result of a
> series of tests done on soil samples taken from near a pt wood retaining
> wall, effectively demonstrating that  the arsenic does not migrate far from
> the wood and  probably poses no health hazard.  This seems
> counter-intuitive; however, no one has yet posted actual test results
> refuting it.
> Do any of you chemists know what arsenic does when exposed to soil
> conditions?  The above would make sense if arsenic decays into less toxic
> substances as it leaches from wood and comes in contact with soil and all
> that soil is.

Arsenic is a naturally-occuring metal.  It is rarely found in it's pure
form; more typically as one of a variety of salts, most of which are
insoluble in water.  The toxicity of the arsenic compound varies with
its valence; the pentavalent form found in PTW is one of the least
toxic.  It is also highly insoluble; which is why it doesn't leach.

Chris Owens

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