Prevent lead poisoning: Get your soil tested
Nathan Brandt, MS
Horticulturists like to reconnect people with nature. Sadly, urban dwellers often are more at home surrounded by concrete and sheetrock than sod and trees. The more unfamiliar urbanites are with whatís outside, the more they tend to fear it. For good reason, nature enthusiasts focus discussion on benefits, and not risks, of spending time outdoors.
A few natural hazards are worth avoiding, like poison ivy, ticks, and sunburns. These risks are easily identified and avoided. A more subtle outdoor hazard is lead in our soil. (Promise you will use this information about lead to improve--not reduce--time you spend in your back yard!)
Lead is a heavy metal commonly used in paint and gasoline in the 20th century. Unfortunately, it was not understood until relatively recently that lead has a damaging effect on most of our internal organs and systems. Consequently, soils were exposed to lead through auto emissions and building demolition for many years. Soil lead levels tend to be higher in urban areas.
Children are very sensitive to lead and are usually exposed to it in the home where lead paint is present. They are also exposed when playing in, or consuming produce from, lead-contaminated soils. If you live in or near urban St. Louis, itís possible your soil contains higher than normal lead levels. If you are concerned about your children being exposed to lead outdoors, you should have your soil tested.
University of Missouri Extension provides soil lead testing. The cost is usually $20 per sample plus a one-time $50 setup fee. While it may seem expensive, this test is a total lead digest, which means results are very reliable. Some labs provide lead testing for as little as $10, but these are extractable values tests and arenít reliable for making decisions about safety of home garden soils.
Some lead is present in all soils. This chart explains different lead levels and the appropriate response to each.
Soil test lead in parts per
Less than 50
Little or no lead contamination in soil.
50 to 400 ppm
Some lead present from human activities. Grow any
vegetable crops. Choose gardening practices that limit dust or soil consumption by children.
400 to 1200 ppm
Do not grow leafy vegetables or root crops. (These crops carry the highest risk of lead contamination.) Choose
gardening practices that limit dust or soil
consumption by children.
Greater than 1,200 ppm
Not recommended for vegetable gardening. Mulch and plant perennial shrubs, ground cover, or grass. Use clean soil in raised beds or containers for vegetable gardening.
Source: Angima, S.D., & Sullivan, D.M. (March 2008). Evaluating and reducing lead hazard in gardens and landscapes. Oregon State University Extension publication
EC 1616-E. http://extension.oregonstate.edu/catalog/pdf/ec/ec1616-e.pdf
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Special offeróSave 50% on lead soil testing! Through Oct. 31, 2011: Get lead soil testing done through St. Louis County Extension for $35 (half off usual $70 fee). For details, contact the author, visit the Web at extension.missouri.edu/stlouis, or contact your local MU Extension county office.
|Editor: Roxanne T. Miller