North American Fruit Explorers mailing list at ibiblio

[Tom Olenio <tolenio@sentex.net>]

Hello,

The critical bit of information missing from this article is where in Chicago 
is this "small" test
area, and how far from heavy industry is it located.  Could this 
contamination have resulted from
poor practices of of 50-100 years ago, when the lead danger was not known, 
and all to common in
products?

This sort of contamination can be very localized, so that is good news.

It is unfortunate that leafy vegetables in contaminated areas may have high 
levels of lead, but
there is an upside.  You can use leafy vegetables to remove heavy metals from 
the soil.

Not sure how you would properly dispose of such plants though.

More good news is that in the small sampling only one had really high levels 
of lead in the
cilantro.  This could have been the result of someone scraping lead paint 
from a urban home 50-100
years ago, the paint chips breaking down in the soil beside the building, and 
today leafy
vegetables grown in taht soil are drawing up the lead from these urban 
gardens.

I am no fan of lead in the soil, but the study is small, and raises more 
questions than answers.
Guess if you are an urban gardener, you should have your soil tested.  But 
then would a homeowner
become liable for a contaminated site?  If you sold the home would you have 
to disclose these
findings to any buyer?  Nobody wins here.

Later,
Tom

mIEKAL aND wrote:

> Lead takes root in urban gardens
> Hazard: A new study suggests that plants from city residential plots
> might contain harmful levels of the toxic metal.
>
> By David Kohn
> Sun Staff
> Originally published November 10, 2003
>
> It seems like such a wholesome undertaking: tending your own little
> urban garden filled with fresh vegetables and herbs.
>
> But some of those homegrown plants might contain potentially dangerous
> levels of lead, according to a new study of Chicago residential gardens.
>
> The greatest hazard was associated with leafy green vegetables and
> herbs. Researchers found traces of the toxic metal in some of the
> plants' leaves - the part people normally eat.
>
> Exposure to lead causes a variety of health problems, particularly in
> children. It can damage the brain, retard growth, impair hearing, and
> trigger mood swings and headaches.
>
> The plants in the study absorbed lead from soil that contained high
> levels of the metal. The study, which appears in the latest edition of
> the journal The Science of the Total Environment, found that lead
> levels were highest in the roots, but in some plants it migrated
> further into the leaves.
>
> "If you grow leafy vegetables and herbs in soil contaminated with lead,
> it's highly likely that those vegetables will be contaminated with
> lead," said Northwestern University environmental engineer Kimberly
> Gray, who oversaw the study.
>
> Root vegetables such as carrots are also likely to absorb high levels
> of lead, she said. But the study tested very few such plants - not
> enough to produce a conclusion.
>
> Although the study was small, it suggests that many urban gardens might
> be producing contaminated plants, said Northwestern researcher Mary
> Finster, a co-author.
>
> She and her colleagues collected 87 vegetables, fruits and herbs from
> 17 gardens in an urban neighborhood in Chicago. The scientists looked
> at four kinds of plants: fruiting plants, leafy greens, herbs and root
> vegetables.
>
> To find out how much lead was likely to be ingested by humans, the
> scientists washed the plants before measuring lead. Even after washing,
> some leafy greens and herbs had measurable lead, indicating that the
> metal was absorbed into plant tissue.
>
> The researchers also tried to calculate whether eating normal amounts
> of the contaminated plants could affect human lead levels.
>
> In some plants, the theoretical amounts of ingested lead exceeded the
> U.S. Food and Drug Administration's safe daily maximum. A tablespoon of
> one sample of dried cilantro contained more than 85 micrograms of lead,
> over 10 times the limit for children under six.
>
> These levels could contribute to health problems, Gray said -
> especially in children, who can be harmed by much lower amounts than
> adults. Women of childbearing age are also at risk because lead can be
> transferred to a fetus.
>
> Nearly all fruits and vegetables showed no signs of lead. While the
> roots of strawberry and tomato plants had high lead levels, the fruits
> had no measurable amount.
>
> The researchers also measured lead in the soil. All samples from yards
> exceeded 400 parts per million (ppm), the Environmental Protection
> Agency's safe limit for children's play areas. Some soils had
> extraordinary amounts, as high as 55,000 ppm.
>
> To minimize contamination risk, Gray recommends planting gardens far
> from lead-painted houses or other buildings - paint particles tend to
> settle close to the structures. She also suggests testing soil for lead
> and, if necessary, replacing it with uncontaminated soil.
>
> Lead contaminates soil mainly through lead paint, which was banned in
> 1978, and leaded gasoline. In the century before it was outlawed in
> 1986, leaded gasoline deposited about 6 million tons of the metal
> across the country, much of it in heavily trafficked cities such as
> Chicago and Baltimore.
>
> A 1983 study of Baltimore yards, for instance, found lead levels as
> high as 10,900 parts per million. "Urban areas are likely to have high
> levels of lead in yards," said Xavier University toxicologist Howard
> Mielke, who did the Baltimore study.
>
> A leading expert on lead in soil, Mielke wasn't surprised by the
> results of the recent Chicago study. He said it underscored a larger
> point - that lead continues to saturate the environment in many large
> cities.
>
> "It has accumulated over the years," he said. "And it's still just
> sitting there."
>
> http://www.sunspot.net/news/nationworld/bal-
> te.lead10nov10001546,0,2651411.story
>
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--
Thomas Olenio
Ontario, Canada
Hardiness Zone 5b