Superfund Research Program

March 2020

Andrew Cooper, Ph.D., collects plant tissues from a fruit tree in the community garden.

Andrew Cooper, Ph.D., collects plant tissues from a fruit tree in the community garden.
(Photo courtesy of UCSD SRP Center)

In a new NIEHS-funded study, Superfund Research Program (SRP) Center researchers revealed elevated levels of heavy metals and arsenic in a local community garden grown on a Brownfields site. By installing raised garden beds on the site, they found that they could grow fruits and vegetables that did not accumulate contaminants.

Brownfields are defined as property whose use is complicated by the presence or potential presence of hazardous substances. These sites are attractive for community gardens because they are often the only land in urban areas not being used for other purposes.

At a Brownfields site in southeastern San Diego, the vacant land has been developed into Ocean View Growing Grounds, an urban community garden and greenspace. However, from 1980 to 2012, the site was used as additional parking and storage for a nearby automotive repair facility, which may have introduced a variety of contaminants into the soil. Today, the University of California, San Diego SRP Center leads a testing program in partnership with the Ocean View Community Garden to identify whether potential contaminants in the soil are accumulating in food grown in the garden.

During the four-year project led by Julian Schroeder, Ph.D., the research team tested fruit trees and seasonal produce for lead, cadmium, and arsenic. They also tested the garden’s soil, finding lead and arsenic above the California Human Health Screening Levels.

The researchers found increased lead levels in Mexican lime and Black Mission fig fruit tree leaves, but not in the fruit that would be eaten. In crops grown directly on the ground, researchers found detectable levels of lead in strawberries and arsenic in leafy greens such as lettuce and Swiss chard.

The community also grew seasonal crops in raised beds. Even though the raised beds lacked a boundary layer with the underlying site, the team did not detect contaminants in the crops. Based on their findings, all seasonal produce at the garden is now planted in raised beds and trees are selected based on soil concentration and contaminants.

Because testing for contaminants can be costly for community-run gardens, the researchers recommend partnering with local universities to reduce the cost of testing for contaminants. Such partnerships give universities a way to apply their work in the community.