lead in soil

lydiakittyMarch 16, 2008

Hi,

I may take a plot in a community garden this spring, which I would use to grow vegetables. I'm in a urban environment, so pollution is a concern. The most recent testing of the soil in this garden shows a level of lead of 80 parts per million. I'm interested in know what people in this forum think - would the veggies grown be safe to eat? Would you serve such vegetables to your family?

I have done some research regarding lead levels...supposedly it occurs naturally in the soil up to about 40 parts per million, and the "dangerous" (it's unclear what that actually means)level is 200 parts per million. I've also read that root vegetables and leafy greens absorb the most lead, and that the main danger from lead contaminated soil is actually the soil itself, and not food grown in it. What do you think?

Thanks everyone!

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len511(6)

Supposedly lead interferes with chlorophyll production, how much i don't know. I think the important question would be how much lead could be absorbed into the plant before it made it unattractive for human consumption, and would that be enough to present any danger.

    Bookmark   March 16, 2008 at 7:55PM
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nc_crn

Sadly, 200 ppm isn't really uncommon.

You should avoid huge plantings of root veggies, yes. Shoot veggies (asparagus/rhubarb/etc) tend to take up a little bit more, but not a huge amount more. You're looking at 10% or less (of the ppm) being uptaken by the fruiting veggies (peppers, tomatoes, etc).

Even though it's probably safe (400ppm is what's allowed on children's playground equipment, for reference) you may want to keep small children from eating a lot of...wait, what am i saying? that shouldn't be a problem. heheh.

Seriously, though...given current knowledge...what you got going on is considered mostly safe though you might not wanna grow asparagus or carrots there if you plan on eating a lot of them in your diet.

There is some debate on the low-growing leafy greens, though...I don't know enough about that to say anything.

    Bookmark   March 16, 2008 at 7:59PM
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nc_crn

"10% or less (of the ppm) being uptaken by the fruiting veggies"

I should say that by 10% or less studies tend to show its closer to 0-5% than 5-10% of the original percentage of ppm.

    Bookmark   March 16, 2008 at 8:01PM
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nc_crn

"I think the important question would be how much lead could be absorbed into the plant before it made it unattractive for human consumption, and would that be enough to present any danger."

You're in a lot more danger not washing your produce more than how much the plants take up.

Most exposure is going to happen where the soil/dust comes in contact with the produce. Root crop lead ppm can be cut severely just by peeling the root before eating it. There is some uptake directly by the plant, but most of the unsafe lead levels in veggies comes from a lack of washing them well more than the lead being incorporated into the plant's tissues.

    Bookmark   March 16, 2008 at 8:11PM
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nc_crn

Here's a study of lead uptake in plants. On page 4-6 there's charts of results of their studies. They studied some VERY high lead soils.

www.bridges4kids.org/lead/binnspaper2003.pdf

    Bookmark   March 16, 2008 at 8:16PM
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justaguy2(5)

nc-crn gives a good link. I always appreciate the studies on topics like this.

80ppm in the soil isn't worth worrying about it would seem.

    Bookmark   March 16, 2008 at 8:56PM
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booberry85(5)

I'm an environmental consultant that deals with lead-based paint issues on a daily basis. The Environmental Protection Agency (EPA) reference levels for lead in soils is not exceed 400 ppm in bare (i.e. no grass or gravel covered) soils in high contact areas (gardens, children's play areas, pet runs, etc), and below 1200 ppm in other parts of the yard where bare soil exists.

Below is the link to part of the EPA regulation. The part regarding soil is on the second page, first column, about half way down under (c).

Here is a link that might be useful: EPA 40 CFR 745.65(c)

    Bookmark   March 16, 2008 at 9:27PM
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lydiakitty

Thanks to everyone for the information...the link from nc-crn was especially helpful. I definitely will follow the recommendations everyone has given, and feel reassured that the food I'm growing is safe.
Thanks again!

    Bookmark   March 16, 2008 at 10:57PM
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granite(z6 NC)

Compost helps to detox your soil, so if you're worried about the levels of harmful stuff in your soil just compost there for 60 days or more and then garden with the area.

Many plants detox the soil, Sunflowers and Indian Mustard are two of the most popular choices.

Check out the document at this link (can't direct link it for some reason):

[DOC]
BROWN PATCH:
File Format: Microsoft Word - View as HTML
Sunflowers (Helianthus sp.) have the ability to remove radioactive and toxic metals from soil and water. Some strains of sunflowers can remove up to 95% of ...
www.natureswayresources.com/DocsPdfs/bioremediation.doc

    Bookmark   March 17, 2008 at 8:15PM
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dcrosby(5MA)

is there a way of testing the soil to see how much lead there is?

    Bookmark   July 20, 2008 at 4:14PM
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booberry85(5)

Below is a list of accredited laboratories. A soil sample should cost around $25.00 to analyze. You will find a shocking amount of difference in price. The laboratory should supply you with the container & paperwork (called a chain of custody) to fill out regarding the sample(s). The lab can also give you some general guidelines on taking the sample.

Here is a link that might be useful: Environmental Lead Lab Approval Program

    Bookmark   July 20, 2008 at 5:59PM
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nc_crn

UMass provides soil testing for lead in your area.

http://www.umass.edu/plsoils/soiltest/services1.htm

It's usually not a big deal unless you're in an area with previous manufacturing/fabrication or near buildings where lead paint has peeled or been scraped off, though.

    Bookmark   July 20, 2008 at 6:02PM
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