Key Points:
- Researchers studying urban farming discovered there are no federal regulations to guide people on the safety of the soil used for growing.
- Urban areas, especially those that have been historically disadvantaged, may have high levels of toxic lead pollution from legacy pollution and industrial use.
- The researchers say federal guidelines are necessary to protect citizens, as well as clearer and more transparent information at the municipal level.
Urban gardens and farms are on the rise in the U.S., but urban soils are sometimes contaminated from legacy pollution and industrial use. Despite this risk, a new study says there is little guidance for people growing food in urban soils on what levels of lead are safe, and existing policies vary widely.
Additionally, urban agriculture can be an important path to food security for historically disadvantaged communities, but those communities are often in areas that are more polluted, including soil pollution.
Currently, the most commonly cited safety level for lead in soil is 400 milligrams of lead per kilogram of soil. But that value, established in 1994 by the Environmental Protection Agency, represents the threshold at which an investigation for residential soil cleanup would occur, not a threshold for safe food production. There are no federal regulations defining safe soil contamination levels for growing food.
The new study, published in American Geophysical Society’s journal GeoHealth, reviewed soil safety policies from the 40 most populous cities in the U.S., plus two additional cities (Minneapolis and Pittsburgh) that the researchers knew had soil safety policies.
Of the 42 cities reviewed, 23 had at least one policy around testing soil, and only 10 had lead-specific policies. Among those 10 policies, the “acceptable” amount of lead in soils varied from 34 to 400 milligrams of lead per kilogram of soil. Eighteen of the top 40 cities lacked any guidance on urban agriculture.
The researchers say these results point to the need for more consistent guidance from the federal level, as well as better access to information at lower municipal levels.
“There are so many benefits from urban agriculture, and it should not be an added route of exposure for communities that already face higher exposure [to contamination] than other communities,” said Sara Lupolt, a public health scientist at Johns Hopkins University who led the new study. “Urban growers and the communities they serve need to be confident they can practice urban agriculture safely and sustainably.”
Information provided by AGU.