Researchers at The Johns Hopkins University Bloomberg School of Public Health said urban soils might harbor contaminants such as lead, petroleum products, paint and asbestos.
The researchers surveyed 70 gardeners from 15 community gardens in Baltimore. They also conducted semi-structured interviews with 18 key experts knowledgeable about community gardening and soil contamination in Baltimore.
"We identified a range of factors, challenges, and needs related to Baltimore community gardeners' perceptions of risk related to soil contamination, including low levels of concern and inconsistent levels of knowledge about heavy metal and organic chemical contaminants, barriers to investigating a garden site's history and conducting soil tests, limited knowledge of best practices for reducing exposure and a need for clear and concise information on how best to prevent and manage soil contamination," Brent F. Kim and colleagues wrote in the study.
"Our results suggest that concern about soil contaminants among community gardeners in Baltimore is generally low, particularly among established gardens. This is likely because gardeners assume soil contamination has already been addressed through safe soil test results, remediation, or the use of raised beds."
However, the researchers pointed out prior studies of Baltimore soils suggested that soil contaminant levels varied widely -- even within the same garden plot -- and at some sites lead levels greatly exceed Environmental Protection Agency screening levels.
Surveyed gardeners were concerned about lead levels, but gardeners demonstrated inconsistent awareness about other potential contaminants, how to test, how to evaluate the results and how to remediate any contamination.
Baltimore's gardeners were more concerned about chemicals added to the gardening environment than what contaminants might already be present in soil. Gardeners' concerns about pesticides reflected the results of prior surveys that found the primary reason consumers purchase organic produce is to reduce exposure to pesticides and other chemicals in their food.
"Efforts to address discrepancies in gardeners' knowledge, however, must be carefully crafted so as to not elevate levels of concern beyond those at which they would discontinue gardening altogether," the researchers said.
[The Johns Hopkins University Bloomberg School of Public Health Center for a Livable Future]
[Urban Community Gardeners' Knowledge and Perceptions of Soil Contaminant Risks in Plos One]