Brownfields and Urban Agriculture - Assessing The Challenges (Part 1)

This post is a continuation of a theme I first began exploring in two previous posts, “The Chicken That Laid Leaden Eggs, and Other Horror Stories,” and “Brownfield Remediation For Urban Homesteaders.” What I discussed in those earlier posts was the problem of soil pollution in urban environments, and the impact of that pollution on efforts to practice safe and sustainable urban farming and urban food gardening.

As noted in those earlier posts, there are many individuals, volunteer groups, nonprofit organizations, research bodies and governments who are tackling the problem of remediation of urban environments in order to foster safe urban food production. Their efforts are vital in helping localities build local food systems so that they can stop relying on industrial factory farming and long, fossil fuel-dependent supply lines stretching from centralized farms to local supermarkets. This last week I had the privilege and opportunity to speak with a member of our own city government, who is involved in the issue of brownfield reclamation. Mr. Clark Henry is an urban planner who serves in the City of Portland Brownfield Program, and he agreed to be interviewed for this blog.

We discussed the extent of urban pollution in the United States, the various kinds of urban soil contaminants, and the costs of some brownfield remediation strategies, as well as the uncertainties associated with these strategies. Following is a transcript of our interview. My questions are in bold type. (I did something different for this interview: I captured it on a digital recorder. I was thinking of making it into a podcast, but in listening to the interview, I wasn't quite satisfied with its pacing (this is my fault, not Mr. Henry's), and I'm not sure I like hearing my own voice...so I chickened out. Maybe next time.) The interview is rather long, so I am breaking it up into two posts. Next week I will post Part Two, God willing.

People talk about adapting to Peak Oil, economic collapse and resource constraints...and there are all sorts of responses, including trying to make things work where we live. Food systems are a big part of this, including urban gardening and urban farming. But some have pointed out the pollution of the urban environment, including pollution of soil due to lead. Telling people, “Don't grow food in the city; it's too dangerous,” won't fly as people find that they can't afford to rely on our present food systems. Yet the issue of pollution is valid. Can you comment on the scope of the problem, starting with lead pollution?

Sure, and just to qualify my statements, I am not a scientist, but an urban planner. I've been working with this [Portland Brownfield Program] project for eight years, so I have developed some understanding of levels and pervasiveness of contaminants. My wife, however, is director of the Josiah Hill III Clinic, a community-based nonprofit organization that does blood lead level testing for pregnant women and children in lower income neighborhoods and among communities of color.

The #1 source of lead contamination in Portland is lead paint, from older construction and older houses. The problem of lead contamination grows more severe as one moves eastward across the United States and as one goes into older neighborhoods. Scraping and sanding paint, or chipping and flaking of paint is the source of soil contamination in the home environment. In commercial and industrial areas, shipbuilding and shipbreaking, bulk oil terminals, old gas stations and old storage sites for leaded gasoline are sources of lead contamination.

Lead is a background element in nature, and agencies like the EPA and HUD publish environmental lead level figures that, in their view, “do not pose a driving risk to human life.” However, they also say that there is no safe level of lead in the human body. And there are documented detrimental effects to small children up to the age of 7 from exposure to lead. The City and County Health Departments partner with the State to publish guidelines for lead exposure, and there is a “Lead Hotline” available to City residents.

What other contaminants are a concern (including organic contaminants like organic compounds from leaking underground tanks)?

Petroleum of all varieties – gasoline, heating oil, motor oil, diesel fuel, bulk oil, and so forth. Former gas stations occupy a large portion of America's commercial corridors, and they were usually situated on corners where people drive by. Many sites of these former stations show few or no signs of such previous use; yet when people look into the records for such sites, they discover that, “Oh, a gas station was here!”

Modern gas stations operate under rigorous oversight by state regulators, but these older sites represent a mystery, an unquantifiable risk, and available databases don't do justice to this risk. Verifiable sites are maintained in two State (Oregon) Department of Environmental Quality (DEQ) databases: the Leaky Underground Storage Tanks (LUSTS) database, and the Environmental Cleanup Site Inventory. Some of the sites on this list have been cleaned up and re-used. All of these sites are candidates for State involvement in assessment and/or clean-up.

There are two stages of State environmental assessment. First is the Phase 1 assessment in which a consultant determines the history of the site, using sources such as the County library, building records, the Polk Directories and the Sanborn Fire Insurance maps. (In the 1950's, the Sanborn Fire Insurance company made very detailed maps of underground tanks for underwriting purposes.) Also, the consultant will visit the site to do a visual inspection, where he may notice old concrete pump islands or old gas station structures or fill ports for underground tanks.

The Phase 2 assessment follows once the consultant has determined that a site is a former gas station or dry cleaners' facility or metal plating facility or so forth. Phase 2 consists of taking soil samples or groundwater samples, or taking samples of the contents of barrels if there are barrels on the site, or taking samples of the materials of any existing buildings or structures on the site.

Once the assessment is finished, the level and type of contamination is compared to the desired future use of the site. The DEQ is concerned with limiting exposure to contaminants. Thus, a site that meets regulatory approval isn't necessarily cleaned up, but is configured in a way that limits exposure – via placing a parking lot or building foundation on top of contaminated soil so that people are prevented from coming in contact with the bare soil. This is called an engineering control. Another form of control, called an institutional control, consists of placing restrictions on the title and permitted uses of the site.

So then, it is possible that there are sites that would be under institutional controls that forbid their use for urban agriculture?

Absolutely. Unless you worked through a new way of getting the site cleaned up. And the City is working with some groups who are researching how to make brownfields both safe and functional for urban agriculture, whether it's small-scale community gardens or something larger. We're working with a group called Groundwork Portland, which is just a year and a few months old. It's part of a network called Groundwork USA, whose mission is to identify brownfields within environmental justice communities, and to have them assessed and cleaned up and re-used in a way that reflects the surrounding community. Not necessarily to eyeball these sites for condominium development or Starbucks, but to make sure that they are doing something for the people who live there – by protecting their health first, and then by insuring that these sites are used in a way that meets the needs of the people around them.

Groundwork Portland has a board of directors whose members come from several local organizations: Organizing People, Activating Leaders (OPAL); the Oregon Tradeswomen; and the Oregon Sustainable Agriculture Land Trust (OSALT). The Oregon Tradeswomen provide training in hazardous waste handling for brownfield work. OSALT owns property for agricultural use and they are doing research on appropriate agricultural development of urban properties. There is a project on 8^th and Emerson in NE Portland, the “Emerson Garden Project,” now being undertaken by OSALT, and it is a 4000 square foot lot that was donated by the County through foreclosure.

The Portland Brownfield Program tested the lot and found that there were really high lead levels in a couple of spots. We (Groundwork Portland, OSALT and the City) are now trying to clean up the soil using phytoremediation (decontamination via plants), in order to turn this lot into a community garden. OSALT will test native plants on this lot, to determine their phytoremedial qualities with lead, in order that we can turn this into a site for food production and education at the same time.

What are the available remediation strategies, starting from the most expensive strategies down to those that are within reach of communities and non-profits?

That's a good question, and the answer is not obvious. Soil removal is one option. But this is very expensive compared to trucking dirt to a regular landfill. Dirt at regular landfills is simply used as a cover. But contaminated dirt requires removal to a toxic waste landfill. Fortunately, there is such a landfill in eastern Oregon, but the cost of trucking dirt there is over $700 a ton, compared to $70 a ton for removal to a regular landfill. And a ton of dirt is not that bulky. So soil removal quickly becomes very expensive, not to mention the cost of finding virgin, clean dirt and trucking it in to your urban agriculture site.

Another strategy is groundwater treatment, but this is an ongoing process that may last several years, and it too is expensive. When dealing with petroleum products, oxygenation and breakdown of compounds using bacteria and/or mushrooms is sometimes used. But this requires continual monitoring. The big questions for bioremediation, and indeed for all remediation, are “How long will this take?”, “How much will this cost?”, and “Who will pay for this?” These are often unknown until one gets into a project. Those who undertake such projects therefore take on a significant risk. Private developers must take this risk on themselves, but communities and tax-exempt non-profits can get help via Federal grants.

* * *

That concludes Part 1 of the interview. Stay tuned for Part 2, where we continue to discuss the costs of remediation strategies. There will also be a debrief and discussion of key points at the end. Meanwhile, here are links to some of the organizations mentioned so far:

• Josiah Hill III Clinic | Working to keep children and their homes safe

• OSALT: The Oregon Sustainable Agriculture Land Trust

• Organizing People, Activating Leaders (OPAL)

• Oregon Tradeswomen Inc.

• Groundwork Portland

• Groundwork USA

The War Against Resilient People

Sometimes, I feel so low down and disgusted,

Can't help but wonder what's been happening to my companions.

Are they lost or are they found?

Have they counted the cost it'll take to bring down

All their earthly principles they're gonna have to abandon?

– Bob Dylan, Slow Train Coming

I'm not yet ready with a follow-up post on fabbers and small-scale manufacturing (I have to work a bit this weekend, just like last weekend), but I thought I'd comment on a couple of news stories I saw this weekend. There's the latest mainstream media report on backyard chickens, from USA Today: “Chickens come home to roost in backyards around the USA.” The article contains the usual photos of blond-haired children cuddling feathered “pets,” as well as listing the familiar benefits of increased food self-sufficiency.

But it also contains statements by politicians in various locales who oppose allowing city dwellers to have backyard chickens. Their objections are ostensibly about the potential for odor, nuisances, abandoned animals and unsanitary conditions. But Iowa City Mayor Regenia Bailey was quite a bit more honest about the real reasons for her opposition: her fears that the achieving of food self-sufficiency by city dwellers might undercut “regional” farmers in her state.

Then there's this article, “Saving The Bed-Stuy Farm,” about a New York inner-city urban farm that is now being threatened with demolition in order to make way for “affordable housing.” The trouble is that the farm has allowed many urban poor people to have inexpensive access to good, healthy food, whereas the “affordable” housing that threatens to replace the farm will most likely simply be “affordable” only in the initial terms of the loans issued to first-time buyers. The housing itself will probably be overpriced in terms of dollar amounts, and will require decades of payments in excess of $1000 a month for homeowners to pay off the loans they incur in order to buy this housing.

The icing on the cake is this item: “Senate Democrats Assured Of 60 Votes To Debate Health Bill.” The so-called health care “reform” legislation they are debating is not really about reform, but will require all Americans to buy health insurance. The only provision for any sort of publicly funded health care is the possibility that the Federal government might provide health “insurance” for people to buy. If the insurance industry can kill that provision, then “health care reform” will mean nothing more than forcing all Americans to give their money to private, for-profit insurance companies. These companies have embarked on a policy of raising their premiums at a rate that far exceeds the rate of inflation. The passage of this legislation will bankrupt large numbers of poor Americans.

The only real sort of health-care reform – a single payer system funded entirely by the U.S. Government – was never even considered by the people in Washington, who are much more interested in spending taxpayer dollars on bailing out gambling-addict mega-bankers, fighting unjust wars, and buying toys for the Department of Homeland Security, who now have their own police force patrolling the streets of major American cities like Portland, Oregon.

All of this is a sorry, yet accurate proof of a statement I made long ago on this blog, that we live and function under a corporatist system that forces as many people as possible into dependence on it, and that it actively opposes anyone who would create a safety net of alternative systems. Yet we seem to love it so. People I talk to at work don't pay much attention to politics or other deeper issues. Anymore, when I talk to them I can see the eyes of many of them glaze over. Maybe it's because they're lazy, or because they're scared of the unpleasant truths they'd have to confront if they did pay attention to deeper issues. Lately, I keep most of my thoughts entirely in my head.

I go to the store, and when I see the magazines in the magazine section, most of them are aimed at getting grown-up adolescents to buy stuff. When I get to the checkout counter, all of the magazines there are taken up with sex and celebrity – full of pictures of airhead doofus adolescent “grown-ups” consumed with their own “cuteness.” This is becoming true even at places like Whole Foods Market and New Seasons – stores which used to prominently feature magazines like Utne, Yes, Adbusters and Mother Jones. Even the so-called “progressive” flavor of mainstream media is increasingly used to maintain a corporatist status quo. The word “progressive” is being redefined to remove any threat to the continued concentration of wealth in the hands of an unrighteous few. The victims of these wealthy are increasingly left without a voice. Yes, there are blogs – but it seems at times that no one reads blogs.

Sometimes I feel so low down and disgusted...

Community-Managed Safety Nets, Food Security and Zenger Farm

It should be fairly obvious by now that the last few decades have seen the tearing apart of government-backed social safety nets in much of the world, and especially in the United States. While it is true that America now has a Democratic president and a Congress controlled by Democrats, their actions to date have not inspired overwhelming confidence that these safety nets might be repaired. (Just look at the present health-care “reform” debate and how our politicians and mainstream media define this in terms of health “insurance” reform. Forcing all Americans to buy private health insurance is not the same as providing universal health care at a cost that our rapidly expanding poor class can afford.)

It is therefore necessary for communities to create their own safety nets. Volunteers must arise to begin building community connections for meeting community needs, often without expecting much help from large government or corporate institutions (though there are cases where communities are pleasantly surprised by offers of government help). A key safety net is the provision of community food security, defined by the World Health Organization as “existing when all people at all times have access to sufficient, safe, nutritious food to maintain a healthy and active life.” (Source: WHO | Food Security)

In the United States, as the standard of living of many people has been eroded over the years, community-based volunteer organizations have arisen to address the growing lack of access to adequate food, and to build systems of community food security. There are the usual food pantries and canned-goods collection drives. But in recent years there have also arisen many urban farming/gardening organizations that promote and teach the growing of food and raising of suitable livestock within urban communities.

I knew nothing about such organizations when I was living in Southern California. But over the last couple of years I have enjoyed getting to know a few of the several community-based, nonprofit urban agriculture organizations here in Portland, and watching some of their extraordinary staff. Many of these people are young, either college students or recent college graduates who have chosen to spend two or more years of their lives as full-time volunteers in these organizations. There is a touch of the otherworldly about them – their education and career paths clearly show that they didn't go to school to get big bucks and a BMW, but they are concerned about larger issues and social justice.

I've interviewed some of these staffers in the past. You can read the interviews here: A Safety Net Of Alternative Systems - Places To Live, in which the Portland Fruit Tree Project was mentioned; and Volunteer Groups And Community Food Security, which featured Growing Gardens. This week's post is another interview, this time featuring Zenger Farm in outer southeast Portland.

Zenger Farm (www.zengerfarm.org) is a century-old working farm that was once owned by Ulrich Zenger, a Swiss dairy farmer, and later by his son, Ulrich Zenger Jr, who protected the farmland from commercial development. In 1994, after the death of Ulrich Jr., the City of Portland's Bureau of Environmental Services purchased the farm. In the years since then, the farm has been leased by concerned citizens who incorporated as Friends of Zenger Farm, a non-profit organization dedicated to preserving the farm as a public space and community resource for sustainable urban food production. Friends of Zenger Farm also works in partnership with the City to oversee a 10-acre wetland adjoining the farm.

On a pleasant, sunny October morning, I had the opportunity to meet with Prairie Hale, Community Involvement Coordinator for Zenger Farm. I was primarily interested in trying to quantify the impact of the farm in building local safety nets and contributing to a resilient community, although there were other things that I wanted to explore. Below are my questions (in bold type), and Prairie's answers.

Has anyone tried to measure or quantify the impact of Zenger Farm on the surrounding community? There has not been a lot of measurement. However, there are general observable impacts. Zenger Farm serves as a place for field trips and educational and volunteer opportunities to learn about the natural world and develop a connection to that world; and to learn about growing, cooking and preserving food, thus fostering self-sufficiency.

The farm is known as a positive place and a good neighbor in the community. The farm staff are aware of what is happening in the neighborhood and are contributing to neighborhood goals. Not only does the farm grow food for the neighborhood, but it forms partnerships with neighbors to run egg co-operatives and farmers markets with the goal of providing culturally appropriate, fresh affordable food for the community. (However, the egg co-op has not yet attracted many members from the surrounding neighborhoods.)

The farmers market is a joint venture with the Lents Food Group, and the market has an “international” flavor. The market has provisions for accepting WIC (Women, Infants and Children) coupons, food stamps and senior coupons, and has a food-stamp matching program.

Field trips to the farm are conducted by local schools and teachers from public, private and alternative schools in the Lents and Powellhurst-Gilbert neighborhoods. The farm also serves as a gathering place to build a sense of community among residents.

The farm is part of a larger urban agriculture “community of knowledge,” both in the Portland metro area and worldwide.

On a related note, what contribution does Zenger Farm make toward building a “resilient community”? (A resilient community is able to survive economic shocks without its members being dislocated by those shocks.) The farm contributes toward increasing food security – that is, a stable supply of affordable healthy food in the neighborhood, as well as generating increasing numbers of people with skills to grow, cook and eat on a tight budget. The farm has offered a very popular class in local schools, named “How to Buy Food On A Budget.” This class has been taught in both English and Spanish, and has attracted both children and their parents.

What are the demographics of the neighborhoods surrounding Zenger Farm? The farm is adjoined by the Lents and Powellhurst-Gilbert neighborhoods. Much of this area is poor, yet many of the residents are actively trying to better their neighborhoods. Twenty-five percent of the population can be classified as “food-insecure.” The area was ranked “last in livability” according to a recent survey. The poor population is also being squeezed by gentrification (the encroachment of wealthy buyers of real estate into the neighborhoods), resulting in rising rents and real estate prices.

For the majority of schoolchildren, English is a second language. Only 30 percent are native English speakers. Spanish is the first language for another thirty percent; then the remainder are from Russian, Vietnamese or Laotian backgrounds. Zenger Farm is actively seeking translators for its classes and workshops.

How would you rate the ability of non-profit groups to make up for the dismantling of social safety nets formerly provided by local governments? There is some uncertainty regarding that question. For residents under stress in a disadvantaged urban neighborhood, worries about personal and family needs might take away energy from community organizing. Also, there is a lot of anonymity in cities, whereas small rural communities tend to be much more tightly-knit, and much more willing to pull together in times of crisis.

However, there are good examples of urban and neighborhood groups meeting neighborhood needs. One example is “Generous Ventures” on southeast 111^th Street, a group that salvages food that might otherwise go to waste, and distributes it to the poor.

What sort of lifestyle adjustments are required of a member of a non-profit organization? (In other words, most of the people I've met from groups like Growing Gardens or the Portland Fruit Tree Project did not go to school in order to get rich!) If someone is going to commit himself or herself to this kind of service, what should their expectations be? Not surprisingly, don't expect to get rich. Seek to gain satisfaction from developing a strong social network so we can take care of one another and provide for our needs.

(At this point, Prairie told me more of the personal events that had led her down this path. She related her family's Quaker background and how she spent most of her life in a small rural Oregon farm community. But as a result of an injury of a family member and loss of income, she and her family found themselves in Ecuador for a year when she was around eleven. That experience, and seeing the drastic difference between American life and the standard of living of the Ecuadoran population, was the catalyst of her interest in social justice.

As a result of that experience, she went to Earlham College, a Quaker institution of higher learning, and obtained a degree in Peace and Global Studies, a field of study which teaches nonviolent ways of bringing peace and social justice where it is lacking. One lesson she remembers is summed up in this saying: “Create the change that the community is ready for.”)

Regarding “closing the loop”: farming tends to deplete soils unless all organic wastes are properly composted and returned to the soil. Zenger Farm does not do humanure composting at this time, but have you ever thought about it? If you tried it, would you do so as part of a larger study of the feasibilty of this sort of composting in an urban environment? Humanure composting is feasible, but it requires a level of expertise and management that Zenger Farm does not yet possess. It seems to be more feasible on the scale of individual homes. As far as composting in general, Zenger buys compost now, but is looking to cut expenses by recycling more of its own plant matter into compost.

Are there any other general research projects being undertaken by Zenger Farm? The farm has not traditionally been involved in research, although a new focus is starting this year, with two farmers who want to try experimental organic techniques. The farm would like to explore other areas of research, such as adding more rainwater catchment and measuring the decrease in use of City water for irrigation when stored rainwater is used. They also want to do more water testing and measurement of sedimentation in the adjacent wetland, and want to explore various furrow and plowing arrangements to limit sediment runoff and erosion.

Do you have any thoughts on remediating urban sites that have been contaminated by industrial pollutants, in order to prepare these sites for urban agriculture? Research has been done on the use of fungi and mushrooms to rehabilitate sites. One prominent worker in this field is Paul Stamitz, a mycologist.

That concluded my interview with Prairie. As I was leaving, I remarked that it was refreshing to see younger people looking for more than a life of materialism and creature comfort (as opposed to my generation, who went to school solely to acquire big houses and BMW's), and that maybe we were witnessing a revival of something that had not been seen in the U.S. since the 1960's. She agreed, and said that it's not just young people who are waking up. Many older people are seeing that the American dream doesn't work, and are starting to want something more meaningful. Maybe there's hope for us after all.

Brownfield Remediation For Urban Homesteaders

Urban homesteading is a very valuable skill set for the times we now face. One of the most important aspects of urban homesteading is for city dwellers to learn to grow their own food. A unique challenge of growing food in an urban or suburban environment is dealing with pre-existing pollution or contamination of an urban garden site. Such sites are known as “brownfields” as opposed to uncontaminated virgin lands called “greenfields.” Brownfields are common in urban areas and we must learn to deal with them, because as the existing “official” food economy deteriorates, we won't be able to just keep going to the store rather face this challenge. Knowing how to garden successfully on brownfields may soon mean the difference between surviving and starving.

Our Endangered “Official” Food System

The food production and distribution system that now exists in the industrial world is becoming increasingly endangered. This system depends on the concentration of control of vast amounts of farmland, labor, machinery, storehouses, distribution facilities and farm “inputs” in the hands of a few large corporations. These corporations distribute food through a vast global network of supply chains that lead to points of sale at local supermarkets. The whole system depends heavily on artificial means of forcing increased production from the ground that is farmed – means such as mechanized farming, pesticides, fertilizers and long-haul transport. All of these artificial means depend on fossil fuels and the cheap credit that a fossil-fueled economy provides.

Now that fossil fuels are becoming scarce, the entire system is beginning to break down. During the last oil price spike, the prices of petroleum-based fertilizers and pesticides also spiked. During the economic collapse that occurred afterward, lines of credit to farmers were wiped out, just as lines of credit for other businesses also dried up. Farmers have come to depend on credit in order to buy the seeds, fertilizers and other amendments, and machinery for each year's harvest. The reduction in availability of credit is causing farmers to cut back on planting. Several news reports predicted in 2008 that this could result in decreased harvests in 2009, leading to price spikes for food, and possible shortages.

This story will play itself out repeatedly and with ever-increasing severity as oil becomes scarcer and the official economy continues to deteriorate as a result. Under such circumstances, city dwellers will need to farm whatever pieces of ground they can get their hands on. Telling such people that it's safer to get their food from the store is a non-starter. Yet it is important to know how to garden safely in urban soils, and how to deal with contamination. In this post, I will focus mainly on dealing with lead contamination. Future posts may delve into how to deal with other kinds of contamination.

Dealing with lead contamination is a multi-pronged strategy consisting of the following elements: appropriate plants, separation techniques, and remediation tools.

Appropriate Plants

All plants accumulate lead to some extent; however, not all plants concentrate accumulated lead in their edible parts. A study performed by the Argonne National Laboratory examined lead accumulation in edible parts of food plants, the results of which showed that lead generally does not concentrate in the “fruit” of fruiting edible plants. These plants include things like fruit trees, corn, cucumbers, peppers, squash, tomatoes, watermelon and zucchini. Therefore, when dealing with heavily contaminated soils (soils that test over 400 parts per million for lead) that cannot be remediated due to cost or lack of access to resources, plants such as these should be cultivated, along with legumes such as beans and peas. Quite a lot of plants can be safely harvested and eaten, even when grown in heavily contaminated soils.

Once the fruiting parts of these plants are harvested, the crop should be washed thoroughly before use. Some sources recommend washing with both water and detergent. Afterward, these crops are quite safe for human consumption. However, it is generally not safe to eat root vegetables, leafy greens or herbs grown in soil contaminated to 400 parts per million or above. Safe utilization of these vegetables requires appropriate separation techniques.

Separation Techniques

When raising root vegetables and other crops susceptible to lead contamination, it is essential to keep these vegetables away from the source of contamination. Therefore, when gardening on a contaminated site, one must not plant these vegetables directly in the soil. Instead, raised beds or containers should be used. Clean soil should be placed in the beds or containers, and the soil should be monitored every season to insure that it does not become contaminated by windblown dust from adjacent contaminated areas. Wind-caused cross-contamination can also be reduced by planting a cover crop of grass in areas of bare dirt to immobilize the soil, as well as by mulch or weed tarps.

Suitable containers for container gardening are easy to come by, free of charge. One can find used five-gallon food-grade plastic buckets at many restaurants and supermarkets. Empty plastic detergent buckets are also good. As far as raised beds, some sources recommend placing a semi-permeable barrier at the bottom of the bed to separate the contaminated soil from the new clean soil added to the bed. The beds must be deep enough that any root vegetables grown in them will not contact the contaminated soil underneath even when they have grown to their full extent.

Gardening in raised beds or containers limits the size of the harvest available to an urban household. In order have the freedom to grow anything anywhere at any time on an urban homestead, soil remediation techniques must be employed where contamination exists.

Remediation Tools

Techniques of remediation of lead contamination have been studied extensively by non-profit urban gardening groups, non-governmental organizations (NGO's), universities and researchers affiliated with the governments of the United States and several other nations. Interest in lead remediation has risen as governments and others have come to grips with some of the negative effects of massive industrialization. The techniques studied have varied in complexity, reliance on advanced technology and cost, with the governments of First World nations tending to favor study of the most costly and complex techniques. These techniques include things like soil removal and replacement, soil washing, electrokinetic methods, and other costly remedies.

Such techniques are beyond the reach of most residents of the Third World, as well as most poor and middle-class people in the First World. I will therefore focus mainly on those techniques which have been studied for use in poor settings by people of limited means.

First, there are techniques of binding lead in soil to reduce its bioavailability to plants. One method, studied in China and in the U.S., involves adding rock phosphate and/or phosphate fertilizers to contaminated soil. The phosphates bind to the lead to form insoluble lead phosphate compounds that are not taken up by plants. Another method is simply to add compost to contaminated soil, as the organic compounds in the compost accomplish the same goal of immobilizing and binding lead in soil.

Then there is phytoremediation, which consists of growing plants that are known lead accumulators in order to reduce the total concentration of lead in soil. Some phytoremediation strategies promise a reduction of 100 parts per million per growing season. Reduction of soil lead levels to an acceptable range by this technique takes from two to over five years. It should be viewed as part of a long-range strategy for healing urban areas.

Final Thoughts: The Correct Way To Assess Contamination Risks

This week's post is a follow-up to my earlier post, “The Chicken That Laid Leaden Eggs, And Other Horror Stories.” In this week's post, I seek to drive home an additional point that I may not have made in the earlier post. That point is the fact that urban homesteading, and particularly urban agriculture, have a disruptive effect on the official global food system, because they result in people breaking free of that system. Therefore it is no surprise that the masters of that system might find it advantageous to try to arouse fear of potential “dangers” of urban food gardening, in order to keep people dependent on the official system.

A recent case in point involves keeping urban chickens for the purpose of eating their eggs. An article appeared in a local newspaper warning urban chicken-keepers of the danger of eating eggs from chickens that have ingested lead-based paint from older buildings. That concern is valid, yet the article went on to imply that because of the ubiquitousness of lead in urban environments, it is largely unsafe for people to raise chickens for food in the city. While the article caused many people to get their property and their children tested for lead contamination, these people then concluded that if there were elevated lead levels on their property and elevated blood lead levels in their children, it had to be due to the children eating eggs from contaminated urban chickens.

Now I believe that the writer of the news article had the best interests of readers at heart. Yet the conclusion of that article and the conclusions drawn by some of its readers seem like “fuzzy” logic to me. I think that before we start blaming urban chickens for childhood lead poisoning, we need to conduct some rigorous experiments, including measuring the lead content of random samples of store-bought eggs, double-blind experiments in which blood lead levels of urban gardeners/chicken keepers are measured against levels of non-gardening urban dwellers, and tissue/egg lead levels of chickens who do not ingest lead paint chips, yet are raised in urban environments. Only after such experiments are performed will we be able to blame or exonerate urban chicken-keeping as a source of lead poisoning. In the meantime, I'm still working on my coop. My plan is to get some chicks in July.

As to the problem of reclaiming brownfields for urban agriculture, I applaud all who are tackling this problem – including the solitary backyard tinkerers doing homegrown research. In finding solutions, you are proving yourselves to be true heroes and heroines.

Sources:

• “Global Markets: The Planting Season And The Credit Crunch,” STRATFOR Global Intelligence, 12 November 2008, http://www.stratfor.com/analysis/20081111_global_markets_planting_season_and_credit_crunch

• “Credit Crunch Could Cost Farmers Dearly in 2009,” Daily Post North Wales, 31 December 2008, http://www.dailypost.co.uk/farming-north-wales/farming-news/2008/12/31/credit-crunch-could-cost-farmers-dearly-in-2009-55578-22584929/

• “Credit Crunch Could Limit Ag Trade,” Missouri Farmer Today, 24 October 2008, http://www.missourifarmertoday.com/articles/2008/10/29/news/crunch.txt

• “Farm-Credit Squeeze May Cut Crops, Spur Food Crisis,” Bloomberg, 27 October 2008, http://www.bloomberg.com/apps/news?sid=a.YrOnFi9aJM&pid=20601087

• “Is There Lead In Your Homegrown Vegetables?”, Argonne National Laboratory, www.dep.anl.gov/p_k-12/women/2007posters/Finster.pdf

• “Lead Levels of Edibles Grown In Contaminated Residential Soils: A Field Survey,” Northwestern University, 28 March 2003, www.garden-guys.com/binnspaper2003.pdf

• “Urban Soils and Backyard Gardens: Potential Contaminants and Remediation Techniques,” Urban Agriculture Notes, http://www.cityfarmer.org/urbansoils.html

• “Soil Lead Remediation: Is Removal The Only Option?”, U.S. EPA Risk Reduction Engineering Laboratory, www.p2pays.org/ref/37/36908.pdf

• “Field Demonstration of Reduction of Lead Availability in Soil And Cabbage (Brassica Chinensis L.) Contaminated By Mining Tailings Using Phosphorus Fertilizers, Journal of Zhejiang University Science, 27 July 2005, http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1361759

• “Biosolids Compost Amendment for Reducing Soil Lead Hazards: A Pilot Study In Urban Yards,” Science of The Total Environment, 20 March 2005, http://www.ars.usda.gov/research/publications/publications.htm?SEQ_NO_115=159411

• “Brownfield Remediation: Solutions For Urban Agriculture,” McGill University, http://mse-research.mcgill.ca/envr401_2002/brownfields/analysis.html

• “Community Gardeners May Be Lead-Removal Pioneers,” Sentinel News Service, 17 April 2009, http://www.portlandsentinel.com/?q=node/4434

Volunteer Groups And Community Food Security

As has been stated repeatedly on this blog, the globalized, industrialized culture of modern advanced civilization is under great and increasing stress, due to resource constraints, climate change and economic collapse. This stress is severe enough to threaten the small units that make up our modern society – the homes, families, streets and neighborhoods in which most of us live. I seek to do my part to investigate strategies for making neighborhoods and communities resilient in the face of our present stresses. In this I am hardly alone, as there are many individuals and groups striving to achieve the same goal.

In America the challenge of achieving resilience is particularly acute, as most Americans acquire necessities by going into debt, thus forcing them to rely on the breaking systems of the “official” economy. Getting out of debt is very hard in many cases, due to rising prices or diminished earning power (i.e., low wages). Those who lose their jobs usually wind up losing almost everything they “own,” since their ownership is based on making monthly payments on an interest-bearing debt. A key, therefore, to getting out of debt and becoming more resilient is finding strategies which allow people to meet a portion of their basic needs for free or at very low cost.

One such strategy is urban food gardening. Yet urban gardening is a challenge in itself, since most Americans don't live on a farm and don't know how to garden for food, having never grown a food crop. I know how much of a challenge this was for me when I started in 2007 in Southern California. Later that year, when I moved to Oregon, I started a garden in my new backyard. I was trying to grow plants I had never seen before, and was anxious that I wouldn't be able to tell a fava bean plant from a weed.

I was greatly helped in my gardening efforts by the discovery of local, non-profit, volunteer groups of people who have made it their business to host classes on gardening, food preparation and food preservation, and who provide help to residents looking to start gardening for food. Growing Gardens, of Portland, Oregon is one such group. I have had the pleasure of attending several classes hosted by them, on subjects such as urban chicken-keeping, winterizing the garden, food preservation and canning, urban chicken-coop building, and seed saving. Their connection to community resilience seemed to be a natural and obvious topic to explore, so I arranged to interview one of their staff to discuss this in more detail.

Thus it was that I got to spend a bit of time with Growing Gardens staffer Rodney Bender last week. We met at their headquarters, a simple rented house which has been turned into offices and storage space to support their activities. Rodney's time was somewhat constrained, as they are very busy with this being the growing season, but he was gracious enough to give me about a half-hour. Here are some questions I asked, along with his answers:

How did Growing Gardens start? During the early 1990's, a gentleman noticed the poverty of some local residents, and began building raised-bed gardens for them, using his own materials and money. As word got out about what he was doing, demand for his services rose quickly, and he soon found himself unable to meet all the needs that were popping up. In 1996, he met a network of volunteers who offered to turn his effort into a non-profit organization to carry on his work. (According to the GG website, this first non-profit was called the Portland Home Garden Project. Later, the name was changed to Growing Gardens.)

What is the mission of Growing Gardens? Their mission is to provide food security to people whose income would normally be insufficient for such security. They do this by transferring skill-sets to people without prior gardening experience, as well as building actual gardens in the yards of low-income residents. Over the years they have installed a large number of gardens, both at single-family homes and in apartment complexes. (Rodney provided an interesting quote: “Give a man a carrot and he will eat for a day; teach a man to grow carrots and he will eat for a lifetime.” I laughed and told him that that was a vegetarian version of a similar slogan I had once heard.)

Rodney spoke of how GG's approach to gardening had evolved over the years. A specific example concerns raised bed gardening. When the project first started, volunteers would build wooden box raised beds in people's yards. However, over time the wood would rot and the soil would be compacted or lost, necessitating an expensive rebuild of the raised bed. This was clearly not sustainable for low-income gardeners, so GG changed its approach to building raised mounds directly on ground level, on top of a layer of newspaper. With this “raised mound”/sheet-mulching approach, installing and maintaining a garden bed is much cheaper.

You said that Growing Gardens has installed apartment gardens. How did that work out? Evidently, they have been able to install gardens in 45 apartment complexes. However, there are unique challenges to starting an apartment garden. First, one must find tenants who are willing and enthusiastic, and obtain permission from the management. This is usually the easy part. The harder part is organizing the daily labor and care needed for a successful garden. Sometimes the original enthusiastic tenants lose interest; sometimes they just move away. In any case, these gardens often wind up as weed patches after a few years. Skillful community outreach and organizing is key to a successful apartment garden.

Is Growing Gardens reaching out city-wide, or are your efforts focused mainly on a certain region? Growing Gardens is focused mainly on the east side for the present. However, they hope to expand to the west as they are able to add staff and resources.

How easy is it to find all of the volunteer helpers and teachers on whom you rely? That part is actually very easy, as GG maintains a listserv where those who want to volunteer can sign up. To date, over 1,000 people have signed up in one capacity or another. (For those Portlanders who are interested, you can sign up here: http://www.growing-gardens.org/volunteer.php)

How do you see urban gardening contributing to the establishment of a strong local economy? Urban gardening is a growing contributor to the local Portland economy, with many local merchants taking an interest. One obvious example is the many local restaurants and farmers' market stands that are now buying and selling garden-raised produce. (That prompted me to ask, “There are broad food-safety laws being proposed in the United States Congress, laws that would impose stringent regulations on food grown for commercial use, no matter where it is grown. How do you see these proposed laws affecting the contribution of urban gardening to our local economy?” Rodney was unaware of bills such as H.R. 875 and its cousins, but my question definitely aroused his interest.)

What advice do you have for people who want to start something similar to Growing Gardens in other cities? First, start small, so that you don't get overwhelmed. If the group's main focus is helping poorer families install home gardens, start with five to ten families at first. Second, keep it simple (especially at first). Begin by teaching simple gardening methods. And where supplies are needed, use free or recycled resources wherever possible.

That concluded our interview. One day I'd like to be a helper (and a witness) at one of their garden installation “parties”; if I can do that, I'll write a post describing it. Growing Gardens is an example for others in other locales to imitate. Another such example is the Portland Fruit Tree Project (http://portlandfruit.org/), a group that collects gleanings from backyard fruit trees in order to donate them to charity. They got their inspiration from a similar fruit tree project in Canada, which now has at least two such projects including the Vancouver Fruit Tree Project (http://www.vcn.bc.ca/fruit/), located in Vancouver, British Columbia, and the Victoria Frut Tree Project (http://www.lifecyclesproject.ca/initiatives/fruit_tree/), located in Victoria, British Columbia. The Victoria Project was featured on a 2006 broadcast of Deconstructing Dinner, a Canadian food security radio program (http://deconstructingdinner.libsyn.com/index.php?post_id=130221).

I have a few closing thoughts on the subject of volunteer groups and food security. First, volunteer groups will play a vital role in establishing resilient neighborhoods, especially those groups that teach self-sufficiency skills. A whole body of knowledge has largely been lost to our generation, which has only known reliance on far-flung global systems for the most part. Second, the Internet is a great resource for connecting with like-minded people. If you have a skill or a benefit that you would like to impart to your local community and you're wondering where to start, you'll probably be able to find someone in another locality who is already doing (or trying to do) what you want to do. Feel free to write others in other localities who are interested in doing the same things. You might even want to arrange visits where you can observe and learn from what others are doing.

Lastly, consider petitioning your local governments for changes in the way they specify greenery for public places. I think particularly of the city easements that exist in front of houses on many residential streets, and how these are usually planted with ornamental, non-fruiting trees. You might suggest that your city use its funds to plant trees that bear useful things like various fruits, nuts and olives. Such plantings would provide the beginnings of a very public safety net of food security.

The Chicken That Laid Leaden Eggs, and Other Horror Stories

I have become interested in raising urban chickens as part of my strategy for decoupling myself from the breaking system of the “official” global economy while living more sustainably. Thus I recently found myself at an urban chicken-keeping class which covered various aspects of the subject, including building backyard chicken coops. During the class, one student mentioned a rather disturbing article that was published in the Portland Tribune on 26 March, titled, “Chickens Eating Lead Not So 'Sustainable.'”

It seems that this article is a response to the explosive popularity of the “urban chicken-keeping movement” in our fair city, and is a criticism of that trend. The author, Tamara Rubin, stated that there is a high risk of lead contamination of the soil of most Portland home lots, due to the lead paint that was used on homes built or painted prior to 1978. She also stated that it takes only two grams of lead dust to heavily contaminate an area the size of a football field. She asserted that chickens on farms are typically less likely to ingest lead, due to the non-lead-based paint used on barns and farms, as well as stating that “most free-range farm chickens and eggs are therefore lead-free.” After giving a few short, general suggestions for testing soil and siting a chicken coop, she concluded by suggesting that the better alternative to backyard chickens is to “[buy] locally farmed, organic, free-range eggs from the store and don't risk inadvertently poisoning your own children in the name of personal sustainability.”

This article hooked my interest, though perhaps not in the way that Ms. Rubin had intended. My interest is always piqued when I hear people warning me or other ordinary citizens away from specific steps toward self-sufficiency. My response is always to ask, “What's really going on here? Is what I'm hearing true? Even if it is true, is it the whole story? Why am I being told these things – especially now?” It was with these questions in mind that I began to study the issue of lead soil contamination in urban areas. This is what I found:

Is It True?

It is a fact that many older urban neighborhoods in the U.S. have soil that is contaminated by lead. The sources of contamination are lead compounds from automobile exhaust and industrial processes, and lead paint on older buildings. The lead from car exhaust was generated by the burning of leaded gasolines, which were gradually phased out in the U.S., starting in 1973 and ending with a complete ban of lead as a component of automotive gasoline in 1996. However, leaded gasoline is still allowed in aircraft, off-road vehicles and farm equipment. The sale of lead paint for residential use was banned in the U.S. in 1978.

Because of the high concentration of heavy industry and car traffic in older inner cities over time, soil lead levels have built up to very high values in these places. The United States Environmental Protection Agency standard sets a maximum “safe” soil lead level of 400 parts per million (PPM) in areas where children are likely to play, and 1,200 ppm elsewhere. As a reference, lead levels in virgin, uncontaminated soil range from 20 to 50 ppm. In cities such as New Orleans, Boston, Detroit and Philadelphia, soil lead levels of nearly 2,000 ppm can be found.

These heavily polluted areas are where poor and ethnic minority populations have historically been concentrated. The small children of these neighborhoods absorb lead via breathing dust and windblown dirt from bare lots, or by ingesting dirt. They frequently suffer central nervous system disturbances as their blood lead levels build to very high values relative to the general population. The children of some of these cities have rates of chronic lead poisoning that are ten times higher than rates of children in affluent suburban neighborhoods.

The lead contamination problems found in older American inner cities is greatly amplified in the cities of the developing world, where environmental and health regulations are much more lax than in the U.S., and where large multinational corporations have moved most of their dirtiest manufacturing operations as a result. The environmental damage wrought by lead pollution prompted this quote from Caltech geochemist Clair C. Patterson: “Sometime in the near future it probably will be shown that the older urban areas of the United States have been rendered more or less uninhabitable by the millions of tons of poisonous industrial lead residues that have accumulated in cities during the past century.” If this is true of the United States, it is true in spades of many places in China, India, South America and other places of outsourced manufacturing.

Lead And Urban Agriculture

Is there a danger then to those who raise their own food in their own backyards? Not as much as one might think. Many studies of this subject have been performed by many groups, including U.S. Government scientists, local universities, local non-profit food security and urban gardening groups, and public-private partnerships between two or more of these agencies. In addition, studies have been performed by NGO's and governments of other nations where lead and heavy-metal soil pollution is a problem. These groups have discovered that lead is not readily absorbed by many plants, nor is it readily concentrated in their tissues to a significant extent. (There are some notable exceptions, however.)

A 2003 study titled, “Lead Levels Of Edibles Grown In Contaminated Residential Soils: A Field Survey,” by Northwestern University, found that those plants that in any way took up or concentrated lead in their tissues did so in their roots first and foremost. Thus, root vegetables such as carrots or onions might absorb between 10 and 21 ppm from growing in highly contaminated soil. Plants were less likely to concentrate lead in their shoots or leaves, although some leafy vegetables like mint had leaf lead levels as high as 60 ppm. Lastly, the fruit portion of fruiting vegetables like corn, beans, grapes and other varieties was least likely to absorb or concentrate any lead. Mitigation of risk from eating these vegetables was easily handled by thorough washing with soap and water. In addition, the 2005 study “Sources, Sinks and Exposure Pathways of Lead In Urban Garden Soil” by Wellesley College concluded that a small child's standard serving of garden vegetables would contribute no more than 10 to 25 percent of the lead found in that child's standard daily portion of tap water.

Then What About Urban Livestock? (Specifically, Chickens)

I was only able to find two studies that directly examined lead uptake and concentration in tissues of chickens. One study, “Lead Contamination of Chicken Eggs And Tissues From A Small Farm Flock,” was cited by Tamara Rubin on her website about lead poisoning, and dealt with chickens that had actually eaten chips of lead paint from an old farm building. While the report states that lead tissue concentrations rose as high as 1,360 parts per billion for the livers of these chickens, concentrations in the eggs of these chickens rose no higher than 450 parts per billion. This study did not analyze the uptake of lead by chickens from polluted soil.

The other study is titled, “The Content of Cadmium And Lead In Muscle And Liver Of Laying Hens Housed In A Copper Industry Region,” and was published by the Agricultural University of Wroclaw, Poland in 2005. This study tracked the lead uptake of two sample groups of hens raised in a region that had formerly been mined for copper, with resulting heavy metal contamination of the soil. This study found that free-range hens and their eggs were likely to have higher concentrations of lead and other toxic heavy metals than their caged counterparts. The weakness of this study is that measurements of soil metal levels were not included, nor were they correlated with the locations of the flocks studied. Therefore, it is not possible from this study to plot the relationship between specific levels of soil and environmental heavy metal pollution and heavy metal blood and tissue levels in chickens raised in this environment.

These studies do indeed show a correlation between environmental sources of lead and increased concentration of lead in poultry tissue. However, these sources do not show the correlation as clearly as it should be shown, especially for lead uptake by poultry on contaminated soil such as is found in urban environments.

There is one other thing to mention, namely that even on regular farms, animals and poultry are being exposed to heavy metal poisoning through exposure to pesticides and inorganic fertilizers. Being on a farm is not necessarily safer in this regard.

Remedies For The Urban Homestead (The Other Side Of The Story)

When one reads Tamara Rubin's writings, as well as the sources I have cited above, one can get the impression that urban gardening and self-sufficiency is scary and dangerous, and that one is better off continuing to rely on the official food system. However, such a conclusion ignores several facts. First, non-profit urban gardening groups and scientists from universities have studied strategies for making urban gardening safe even where soil is contaminated. Northwestern University has published the following recommendations for urban gardeners:

• Survey the property to determine the potential lead hazards, extent of the contamination and location of high-risk areas.

• Plan to locate fruit and vegetable gardens away from buildings, especially if peeling paint is evident and sites where sludge with heavy metals was applied.

• Analyze lead concentration in soil samples from areas where vegetable gardens exist or are planned.

• Do not grow food crops in a soil that is contaminated to levels greater than 400 ppm. Instead, use either containers or construct raised beds, with a semi-permeable barrier between the clean and contaminated soil.

• Where container or raised bed gardening is not possible, fruiting crops should be grown.

• Root vegetables, leafy greens and herbs should not be planted in contaminated soils.

• Test new topsoil before using it and annually retest the garden soil to monitor for recontamination.

• Do not use plants grown in contaminated soils for compost.

• Use mulch or a weed tarp in garden beds to reduce the potential for aerial soil dust deposition or soil splash up on crops.

Others have studied the effect of adding various soil amendments to reduce soil lead bioavailability. One such study, conducted by Hangzhou University in China, discovered that adding phosphorus to lead-contaminated soil bound the lead and made it insoluble, thus less able to be absorbed by plants. Other studies have shown that adding raising soil pH or adding compost and manure to contaminated soil reduces the bioavailability of lead. Lastly, there are agencies who are studying phytoremediation techniques, where specially selected plants are used to draw lead out of contaminated soil in order to reduce total soil lead concentrations. While the other techniques have documented success, phytoremediation is still in an early, experimental stage. And as for chickens, there are several very simple strategies that can be employed in the building of their coops and runs to keep them from coming into contact with contaminated soil.

But before anyone rushes out to secure remedies for soil contamination, the first step is to get your soil tested by a reputable laboratory. It may be that you live in an area that is not heavily polluted.

Conclusion: Bustin' Loose From The System

Having examined the evidence behind Ms. Rubin's article, I believe that she does raise some legitimate concerns regarding lead contamination of urban soils. However, I disagree with the tone of her article, because it forces ordinary, average people of small means into a corner. These are the people who are being squeezed and bruised by their continued reliance on the breaking system known as the official economy. Last year, most of them found it increasingly hard to afford food and fuel as resource shortages led to skyrocketing prices. Most of them even now are being crushed by the weight of unsustainable debt. Very soon they will be squeezed yet again by rising food prices. Midst all of this, they are losing their jobs at a terrifying rate.

What shall we say to such people? “Don't garden; don't raise urban livestock, don't try to be self-sufficient; it's too dangerous”? Shall we tell people that they can only get their food from the store? Shall we pass laws making self-sufficiency illegal? That will go over about as well as a lead chicken. We can't not garden; we can't not keep urban chickens; we can't not learn self-sufficiency. We have to pursue these things. Rather than trying to scare people away from self-sufficiency, let's work on fixing that which has become so broken, while going after the people who did the breaking in the first place.

I'd have been much happier with Ms. Rubin's article if she had mentioned the public/private partnerships between Government and University researchers and urban food security non-profit groups to find remedies for lead soil contamination. I'd have been much happier if she had suggested pressuring the government to make urban polluters clean up urban neighborhoods instead of trying to scare people away from raising backyard chickens. The truth is that the city is where most of us will take our stand, where we will rise or fall in our efforts to carve out a meaningful life to hand down to our descendants amid the crises now converging upon us. We can't all run away to the farm, nor can we continue to rely on a breaking system. As Bruce Sterling said, “The ruins of the unsustainable are the 21^st Century's frontier.” We're starting to live in those ruins now. That's where the new pioneers will make their stand. Whatever's broken, it will be up to them to make it work. There is no other choice.

Sources:

• “Field Demonstration of Reduction of Lead Availability in Soil And Cabbage (Brassica Chinensis L.) Contaminated By Mining Tailings Using Phosphorus Fertilizers,” Journal of Zhejiang University Science, 2006, http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1361759

• “Sources, Sinks, And Exposure Pathways of Lead In Urban Garden Soil,” Journal of Environmental Quality, 27 October 2006, http://jeq.scijournals.org/cgi/content/full/35/6/2066

• “Lead In The Home Garden And Urban Soil Environment,” University of Minnesota, 2002, http://www.extension.umn.edu/distribution/horticulture/DG2543.html

• A Resource Guide: The Phytoremediation of Lead in Urban, Residential Soils, Northwestern University, http://www.civil.northwestern.edu/EHE/HTML_KAG/Kimweb/MEOP/INDEX.HTM

• Urban Gardens: Lead Exposure, Recontamination Mechanisms, and Implications For Remediation Design, Department of Geosciences, Wellesley College, Wellesley, MA, July 2008 http://www.ncbi.nlm.nih.gov/pubmed/18456252

• Greennet Chicago, Chicago's Greening Network, Publications Page, http://www.greennetchicago.org/soil_contamination.html

• The Annual Conference On Soils, Sediments, Water And Energy (Formerly known as the Annual Conference On Contaminated Soils), http://www.umasssoils.com/

• “City Soil Lead Exposure Maps,” http://urbanleadpoisoning.com/maps.html

• “Lead In Soil,” Lead's Urban Legacy, Tulane University,

• http://www.som.tulane.edu/cbr/ecme/leadhome/soil.html

• “Lead for Car Batteries Poisons An African Town,” MSNBC, 4 January 2009, http://www.msnbc.msn.com/id/28484477/

• “Lead Contamination of Chicken Eggs And Tissues From A Small Farm Flock,” Journal of Veterinary Diagnostic Investigation, 2003, http://jvdi.org/cgi/content/abstract/15/5/418