Interest in vegetable gardening is growing, thanks in part to rising food costs, ecological concerns and incidents of foodborne illness related to produce.

Just how many backyards are becoming food gardens is hard to enumerate, but the American Community Gardening Association estimates there are now more than 18,000 community gardens in the United States and Canada.

While many community gardens exist in rural areas — such as one in Cambridge, New York, on the site of a former trial garden for the Asgrow Seed Company — community gardens are also urban endeavors. 

In either setting, soil toxicity can be an issue. Rural areas might suffer from agriculture exposure, such as orchards where the residue of lead arsenate applications can remain in soils.

“(For) urban gardeners the main contaminant of concern is going to be lead, which is fairly common because of lead paint chipping off houses and becoming airborne, and from lead used in gasoline up until the 1970s,” said Scott Kellogg, educational director at The Radix Ecological Sustainability Center in Albany, New York. 

According to the Centers for Disease Control and Prevention (CDC), lead poisoning affects more than 1 million children in the country.  Most of these cases are from exposure to lead paint in homes or from lead-contaminated house dust or soil. Kids may ingest or inhale contaminated soil in gardens, playgrounds or yards. Lead may also affect vegetables, particularly root crops or leafy greens. 

But lead is not the only potential problem with urban soils. Petroleum and waste oils, volatile organic compounds (VOCs), pesticides and polycyclic aromatic hydrocarbons (PAHs), and metals can also be present.  The U.S. Environmental Protection Agency and its brownfields program is a starting place for people and groups looking to deal with contaminated soils.

Last week, the 14th annual Brownfields Conference was held in Philadelphia.  A joint effort of the EPA and the International City/County Management Association, this year’s conference was the largest ever, with almost 6,000 people in attendance.  Nine out of more than a hundred sessions focused on urban agriculture, school gardens, composting and the importance of safe soils.  

The free, three-day event attracted environmental professionals, states, tribes, community groups, brownfield grantees and communities interested in seeking brownfield grants. 

“We also welcomed architects, law firms and legal experts as well as public health practitioners, environmental justice and community advocates, and students from five Philadelphia area universities and colleges who organized design charrettes on area sites, providing new community visions for those locations,” said a spokesman from the EPA.

The conference inspired a pop-up art event with scientific roots called the Soil Kitchen.  From April 1-6, members of the artist group Futurefarmers served soup in exchange for soil samples, and hosted a number of educational events, too.  By April 5, 300 samples had been collected, reaching the capacity of the EPA’s mobile soil-testing lab.  Results of the tests will be used to create the Philadelphia Brownfields Map and Soil Archive.

The conference was an opportunity to spread the word about an urban agriculture website launched last September by the Office of Solid Waste and Emergency Response (OSWER), the sector of the EPA that handles brownfields. The website is a clearinghouse for information on soil testing, applying for grants and issues pertinent to urban agriculture.  The assistant administrator of OSWER, Mathy Stanislaus, has made urban agriculture one of his priorities for land revitalization, particularly in underserved communities.  

Across the country, $1.5 billion in federal funding has gone to clean up brownfields sites since the mid 1990s. Brownfields grants are used to assess and remediate land. Certain contaminants on some sites are addressed by phytotechnologies, using plants to achieve environmental cleanup.

According to the EPA, several communities are looking at how they can include community gardens or urban agriculture projects as part of their brownfields revitalization planning. The agency funds Kansas State University to provide support and technical assistance to communities planning gardens.

In many instances, groups employ brownfields funds to remediate sites prior to creating gardens. Others, like a longtime community garden in Fremont, CA, are cleaned up after being discovered to be contaminated with PAHs, lead and pesticides.

Community and state initiatives are studying and attacking the issue of soil toxicity, too.  

“My position here at Cornell Waste Management Institute really came out of the fact that we were getting an increasing number of questions from gardeners who were wondering if they should be concerned about contaminants,” said Hannah Shayler, who is working on the Healthy Soils, Healthy Communities research project.  

Funded by the National Institute of Health, the project involves Cornell University, Cornell Cooperative Extension in New York City, the New York State Department of Health and GreenThumb, the arm of the NYC Parks Department that handles community gardening. 

People calling Cornell wondered if they should test their soils, how to test them, and how to interpret whatever results they found.

“All of that really led us to the understanding that there were some pieces to be filled in and there was a need for a broader research program to get some science-based answers to these questions so that then we have more information to share with people,” said Shayler.

The four-year project began field work last summer, and focused on testing soils last year, largely from 75 different gardens in New York City.  This year they will interview as many gardeners as possible, and test produce.  As the project gathers data, it is also engaging in outreach such as workshops and discussion groups to try to educate the public on what is known about growing food on potentially contaminated or contaminated land.  

“The last thing we want to do is have people avoid gardening or stop gardening because of concerns about the soil,” said Shayler.  Yet discussing the research can elevate concerns, and so people involved in the grant are sure to distribute information on how to handle soils and food.

Raised beds are good choices in some sites, and mulching around plants and between vegetable beds minimizes dust that can distribute lead and other contaminants.  Washing produce and washing hands is advocated, as is keeping soil healthy and ph neutral, because lead in acid soils is more bioavailable. 

“In instances of extreme contamination, the dig and dump method (is used),” said Scott Kellogg of The Radix Ecologial Sustainability Center.  “For really low level contamination, sometimes what’s done is you add compost to the soil.  By adding more clean material you’re reducing the concentration of contaminants.”

If that clean material is compost, Kellogg said, the lead is essentially locked up in the structure of the compost itself.  This reduces the bioavailabity of the lead, which makes it less apt to be taken up by plants.  Also, if accidentally ingested, the lead is more likely to pass t
hrough your body rather th
an to bind to some receptor site in your brain or in your body tissues.

Toxic Soil Busters works on soil in Worcester, MA. The youth-run cooperative began in 2001 as an all-volunteer effort, and by 2005 the young workers, ages 14-19, were paid employees.  Currently, 17 youths are working part time to educate people in the city on contamination in soils, and work to mitigate those problems with a variety of strategies.  The group is experimenting with phytotechnologies, using plants such as geraniums, sunflowers and Indian mustards to take up contaminants in affected areas.

Operating as contractors for HUD and for private homeowners, the Toxic Soil Busters remediate affected yards. The group uses physical barriers like landscape fabric and mulch to separate the contaminated soil from contact with people and plants. Adding clean soils dilutes the concentration of lead, and raised beds are also employed.

Toxic Soil Busters presents workshops at high schools and community events, like an annual block party. The very motivated youth workers create skits, videos and other media messages to deliver information about lead and other contaminants.  

This summer, the workers will tackle 7-12 yards.  This fall, the organization will celebrate 10 years in operation.