Monday, March 9, 2015

Lead contamination in urban soil – Should we be concerned?




A popular modern trend is creating sustainable gardens in urban spaces. These can range anywhere from community gardens, commercial gardens that sell to local restaurants or farmers markets, and even personal backyard gardens. Whatever the purpose may be, these are typically gardens where food is grown and harvested for human consumption and the threat of contaminated soil is very prevalent.

Lead was used in household paint as late as 1978 and in gasoline as late as 1986. As a result, it is not uncommon for urban gardens to have high concentrations of this heavy metal, especially those near heavily trafficked roads and places around sites where old houses have been torn down. Above ground crops like tomatoes are of low concern as the lead in soils isn’t absorbed into the harvested parts of the plant in significant amounts, as long as the vegetables are washed of possible contaminated dust before consuming. Root vegetables are of greater concern as the edible parts of the plant are growing below the ground, where they can absorb things like lead in much higher quantities.

Adults can absorb 11 percent of the lead in food they consume but children are at a much higher risk and can absorb anywhere from 30-75 percent. The greatest concern is for the people who tend to these gardens as a study showed that people gardening in an area with high levels of lead had an elevated level of lead in their blood compared to a community with no lead, up to 28 percent higher.

Lead has been associated with intelligence and behavior issues in children and in adults it can affect most parts of the body, including the brain and reproductive organs.  When consumed, lead dissolves after coming into contact with stomach acid and then attaches itself to our bones. Solutions like removing and replacing contaminated topsoil is very expensive so people are looking to solve the problem with more inexpensive and natural solutions such as building raised beds and by composting. Composting with phosphorous materials such as food scraps or bone meal allows lead to attach itself to that material before it can attach to our bones.

High levels of lead in urban soil shouldn’t deter people from planting there but it is something that should not be taken lightly. Tests are available to find out if the soil you are planning on using is contaminated and to what degree. Simply being aware is the biggest step to discover what needs to be done in order to prevent this from being an even bigger issue to future communities.

Added by Will Baker

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