Subject: Lead, community gardens and food

From: Karen Paulsell <[email-masked]>
Date: 12 Mar 1994 19:31:42 GMT

We're just starting a community garden on (hopefully) two lots in Oakland,
CA. We got the lead-testing done, one lot is OK, at ~200 PPM, but the
other is pretty bad: ~4000 PPM. We took about a dozen samples from each
lot and made two composite samples  for this first test...we plan to go
back to the bad one, and take several discrete samples, especially from
a couple of spots where the soil is noticeably different than the rest.

Total "abatement" by removing the soil (if the whole lot is affected)
is (financially) out of the question, but raised beds or other methods
can be accomplished.

But I'd like to learn a lot more about lead. And food, and what food plants
are affected, and how, and remediation. It's especially important because
we're going to have classes from 2 grade schools participating, as well
as a local Teen Center, Senior Center, Alcohol Recovery Program, and
just plain folks.

I know the local community gardening association has some info, but I 
thought I'd ask the plant-science community. Online source especially
appreciated; as a non-academic, my access to really good libraries is
difficult (though still possible).

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From: Kelly Cassidy <[email-masked]>
Date: 13 Mar 1994 18:11:03 GMT

(Worried about lead in soil.)  

>From what I remember about lead and plants, your main worry
will be children eating the soil.  Plants do not take up
lead readily via the roots.  Lead from contaminated air does
bond to leaf surfaces, but since most gasoline is now lead-
free that should not be a problem.  

I would advise further research, though. Pertinent questions
are:
Will soil acidity affect lead uptake and, if so, how acidic
is the soil?
Do some plants take up lead more than others?
If there is uptake, is the lead concentrated in a particular
plant part, like the leaves or roots.

If you are concerned, raised beds would seem to solve any
problem.

Kelly Cassidy

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From: Oliver Sparrow <[email-masked]>
Date: Mon, 14 Mar 1994 07:57:00 +0000

Lead is, of course, found naturally in places where people have
lived for millenia without drawing medical attention upon themselves 
for their unusual medical histories. Areas of Derbyshire, in Britain, 
are built upon low-grade lead ores and this seems to cause no ill
effects. As a previous entry indicated, few plants take up lead and
few forms of lead as sufficiently soluble to become biologically 
active in the human.

An interesting historical aside is that Britain suffered a plague of
gout during the Napoleonic wars. It appears that the claret-drinking
classes turned to cider during the period of hostility. Cider was brewed 
by crushing apples in ball mills, in which the balls were often made of 
lead. (Iron was cheaper, but dissolved). As a consequence (and as a 
result of the enormous amount of cider which they drank) many came
down with lead poisoning, a few consequences of which are the accumulation
of uric acid in the blood stream (and joints - hence the gout) and
dementia (hence the Rowlandson cartoons of choleric squires in bath chairs).
Bath chairs are themselves an icon of the era and a consequernce of the
malady. Taking the waters at Bath flooded the system with divalent cations
(Ca, Mg in particular) and these tend to displace Lead from where it has
accumulated. After a week or so of abstinence at the spa, our squire would 
be mobile, stable and himself again, until her returned to the cider!
_______________________________________________

  Oliver Sparrow
  [email-masked]