Lead and Soil
New US EPA guidance lowers the action level for lead in soil.
Jan 25, 2024. KSHD Promising results': K-State PhD students work in KC to pioneer cost-effective way of reducing lead in soil. "Researchers and PhD students with Kansas State University are using Kansas City as a model to pioneer a cost-effective and efficient way of reducing lead's presence in soil through the use of environmentally safe chemicals."
January 17, 2024. Press Release. Biden-Harris Administration Strengthens Safeguards to Protect Families and Children from Lead in Contaminated Soil at Residential Sites "Utilizing updated, best available science, EPA lowers screening levels for the first time in 30 years. [ ] EPA is lowering the screening level for lead in soil at residential properties from 400 parts per million (ppm) to 200 ppm. At residential properties with multiple sources of lead exposure, EPA will generally use 100 ppm as the screening level. Screening levels are not cleanup standards. While this update will help EPA site teams make site-specific cleanup decisions to protect nearby communities, EPA makes cleanup decisions specific to each site, using site-specific factors, including risk factors and community input that can vary from site to site. [ ] While the guidance goes into effect immediately, EPA welcomes feedback from the public that may be considered in any future updates to the guidance. Please submit written feedback on the guidance in the public docket (Docket ID: EPA-HQ-OLEM-2023-0664) for 60 days from January 17, 2024, to March 17, 2024.
What can property owners do to address high lead levels in soil?
There's no simple answer to remediating lead in soil.
The three "traditional" methods to deal with lead contaminated soil
Removal of contaminated soil to a licensed landfill. Expensive
Cover bare soil with 6" of mulch. Mulch coverings should be tested for lead content. Chipped wood mulch *could* have lead contamination.
Establish a solid covering of grass and keep bare spots reseeded through the year.
Anything that is a barrier between the contaminated soil and the children should work. The fact that your grandchildren have not picked up lead from the grassy area suggests that you have that space under control.
EPA recommends planting plants that can absorb lead, but CLASH is skeptical. Sunflowers, hemp, and tomatoes are all plants noted for being lead bioaccumulators. The problem is these plants cannot be burned, buried or composted without releasing the lead back into the soil. Here's a study,
Potential of Industrial Hemp for Phytoremediation of Heavy Metals. "The accumulation of anthropogenic heavy metals in soil is a major form of pollution. Such potentially toxic elements are nonbiodegradable and persist for many years as threats to human and environmental health. Traditional forms of remediation are costly and potentially damaging to the land. An alternative strategy is phytoremediation, where plants are used to capture metals from the environment. Industrial hemp (Cannabis sativa) is a promising candidate for phytoremediation. Hemp has deep roots and is tolerant to the accumulation of different metals. In addition, the crop biomass has many potential commercial uses after harvesting is completed. Furthermore, the recent availability of an annotated genome sequence provides a powerful tool for the bioengineering of C. sativa for better phytoremediation."
Gardners can avoid contact with lead by building raised bed gardens. Use a plastic liner at the bottom of the bed then fill with clean soil to a level of 8" to a foot.
There's been some research on the use of Triple Superphosphate (TSP) Phosphate on soil to bind to lead and make the lead insoluble so that it can't be absorbed by the body.
Kitty litter? https://news.yahoo.com/common-cat-litter-ingredient-help-103010092.html. We never heard of this before! More research needed.
Where do toxic hazards in soil come from?
Abandoned automobiles can leak fluids on to the ground. Abandoned houses where there is chipping and peeling paint can spread lead dust to surrounding areas.
Exhaust from leaded gasoline (outlawed in the mid1980s) are still lurking in bare soil areas. Sites where cars, trucks, and buses sat idling are likely sources of lead pollution.
Highway and train overpasses are likely spots for lead contamination where structures are rusting and chipping.
Industrial emissions from plants which process metals can travel from smokestacks for miles in all directions. You won’t know if you have toxic elements until your soil is tested.
Demolished houses where there was lead paint were often buried on site. Over the years the lead in the buried debris can come to the surface where people walk and play.