Does University of Maine Cooperative Extension test plants for lead?
Question:
The UVM Extension services appeared to indicate that I might be able to get plant materials tested (for a fee of course) through the Maine Extension services. I have plants growing where there is known to be lead. I would like to test parts of the plants to see if lead is showing up in them. Is that something you do? And if not, do you know where I can get that done?
Answer:
Unfortunately, I’m unaware of any services that test *plants* for lead content, though our UMaine Analytical Soil Lab does test for its presence in soil samples. Lead does not translocate easily through plants’ vascular tissue, so the risk of lead exposure is typically through consumption of surfaces that have been splashed with contaminated soil or inhalation of soil particles while gardening. Because of this, thorough washing generally mitigates the risk, as does categorizing exposure risk by part of the plant consumed–root vegetables like carrots, potatoes, or beets are at highest risk of containing lead (with the potential for actual lead penetration into plant tissue), stems and foliage in the middle, and fruits at the lowest risk (the last two risky because of surface soil particles).
You can see EPA recommendations for gardening in lead-contaminated soil in this great Univ of MD Extension page, “Lead in Garden Soils.” The gist is that <50ppm is generally considered safe with good washing (this is more or less the normal amount of naturally occurring lead found in healthy garden soil), 50-400ppm can be gardened in with good washing and some precautions like peeling root crops, and 400-1000ppm only fruiting crops with leafy greens and roots relegated to containers or other locations. Obviously, these are guidelines and the home gardener will have to use their own judgment to determine the risk they are willing to tolerate. We can’t guarantee that there won’t be lead exposure from gardening in soil known to be contaminated, and if you are at all concerned you should consider constructing raised beds for your gardening needs.