Showing posts with label lead contamination. Show all posts
Showing posts with label lead contamination. Show all posts

Saturday, January 23, 2010

Brownfields and Urban Agriculture - Assessing The Challenges (Part 2)

This is the second part of a transcript of an interview I conducted last week with Clark Henry of the Portland Brownfield Program. In this interview, we discussed the prevalence of brownfields (areas of land polluted by commercial or industrial activity) in urban environments, and the implications for urban agriculture and food gardening. Today's post contains the remainder of that interview, in which solutions to brownfields are discussed. For the sake of continuity, I have also included all of the transcription from last week's post. My questions are in bold type, and Mr. Henry's answers are in normal type.

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 8th 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.

The Portland Brownfield Program focuses most of its efforts on helping community-based revitalization efforts, and I think we've achieved some good successes. But we also help private markets figure out remediation, as even large private firms who specialize in brownfield redevelopment sometimes get in trouble.

As far as nonprofits, there's a group, Southeast Uplift, that owns a former gas station on southeast 57th and Division. This land was given to them by the U.S. Marshal. This site was known to have underground storage tanks that had leaked. We helped them deal with the environmental liability issues and obtain the resources to deal with regulatory requirements for dealing with the site's past use. Our approach was straightforward – “dig it up and haul it away.” Fortunately, when we started digging out the tanks, we found very little contamination. But a site with identical usage and identical tanks might have had monstrous contamination – you just doesn't know until you start digging. We can test all we want, but the reality is that we drill a series of holes spaced a certain distance apart, and we make assumptions about what lies between those holes. If we find contamination, we will drill more holes until we don't find any more. This helps us determine the zone to be cleaned up. But the testing is expensive, and it is not fast. We can make educated assumptions about what we hope to find, and then have a plan B – a healthy contingency. Private developers have the luxury of having a large investment pool for cleaning up land for large projects, such as the Pearl District and South Waterfront. Things get tighter as the project size shrinks, though there are State and Federal grants available to tax-exempt organizations and nonprofits.

It sounds like there really needs to be a partnership with city governments in order to promote urban agriculture. The extent of urban pollution is fairly widespread. Are you saying then that people should not rush in blindly and grow vegetables in any bare patch of land?

Yes, that's a fair assumption. But it depends on what you're growing – does your tomato plant take lead out of the soil and store it in the fruit? It's questionable. Look at the literature to see what contaminants plants actually take up. The more serious threat comes not from eating the vegetables, but from working the soil – digging, planting, then bringing contaminated soil into your home.

The National Brownfield Conference was recently held in New Orleans. My co-worker Jen was there, and spoke at an urban agriculture session. There was also a woman named Anne Carroll of the U.S. Environmental Protection Agency who is working with city groups to help accurately communicate the risk – there really aren't a lot of regulatory standards that people can follow to determine what's safe; most of it is perception.

At that Conference, one researcher from the University of Washington said, “There's a very scientific approach to this; there's very little risk, so why address it? We haven't seen plants take up contaminants; all you're doing by applying this stigma to areas of land is stopping people from growing food. There's no risk; just go ahead and do it.” To me such a statement sends up a red flag – because people don't necessarily respond well to purely scientific reasoning. Even if that reasoning is communicated clearly, people don't always respond well. For instance, if you were told, “That soil is safe for you to garden in so long as you and your children aren't consuming more than 18 percent of your annual broccoli intake from that plot,” how would you feel? Perception of risk – perception of contamination is everything. Perception that a site is too dangerous to use may cause it to lie fallow, unused for anything- along with the perception that any assessment or remediation is too costly to undertake.

This is why partnership with a city government or other group that understands these issues can help in reusing sites. This is why we have been working with OSALT on the 8th and Emerson site, and why we have been working with Anne Carroll on accurately communicating the risk, and what to do to manage the risk. Not everyone who wants to start a community garden has a few hundred thousand dollars to remove the existing soil and bring in verified clean, composted new soil – that's unrealistic. So what's the alternative? To not use land? To use only the most pristine land? The vast majority of this world exists right in the middle, and if we want to use urban land for agricultural uses, we will be walking with some risk. That's okay, as long as we understand the risk and we take reasonable steps to limit it.

There are some obvious no-no's – you don't plant directly in extremely contaminated soil, for instance. And composting has been shown to bind contaminants in soil so that they are not mobile and can't be absorbed by plants. But some of this is subjective. And one size doesn't fit all. What's needed is an arsenal of many tools to deal with contamination in many situations.

One question is “What does sustainable cleanup really mean?” Does sustainable brownfield redevelopment consist of digging up contaminated soil and hauling it to a landfill? That just makes it someone else's problem. These landfills don't remain landfills forever. We're already dealing with the problem of closed landfills, and the big voids they leave in the urban environment. Landfills are big. Once they get closed, normally nothing happens on them. Will we try technologies and products that clean soil and groundwater? Do these products really do what they're supposed to do? Or do they actually make the contaminants more toxic?

Are there other cities throughout the U.S. and the world whose city governments are working to reclaim brownfield sites in their city limits for use in urban agriculture?

Yeah, absolutely. Philadelphia has been receiving national attention for their “Philadelphia Green” efforts. There's a group in Milwaukee, Wisconsin – I feel bad because I can't remember the man's name – but there's a gentleman who has done a tremendous job with aquaculture and urban agriculture, and he's doing it in a way that's educating tons of people, while generating enough funds to support itself; it's economically viable. There's also the Groundwork USA network. New York City is also looking at this as far as urban gardening, and they recently launched a very ambitious Brownfield Revitalization office.

Germany has a very interesting “Interim Use” philosophy. If a site is not being used, the government asks, “What can we use this for?” They don't have the same “property rights” gusto found in the USA, so the German government has a lot more statutory authority to put sites to use when their owners leave them fenced off and contaminated. Urban agriculture is one of the uses Germany has looked at for these sites, particularly in Leipzig.

In Indianapolis, my counterpart is Christopher Harrell, and he's looking at this as well. We're definitely not unique, but we like to think we're doing good work.

So here we are and someone wakes up to the insecurity of our economy and our industrial food system, and as he thinks of the need to start building local economic systems and systems of food production, he looks out his apartment window at the vacant lot across the street. Where does this person start?

Talk to the property owner if you're thinking of using some vacant land. Then, do your research on the site's history. In Portland, the Polk Directories are a good resource. Then, if you find that the site has a history that might have generated contamination, do some testing. Call the Portland Brownfield program. Also, talk to neighbors who know the history of the site.

But should you find that the site is contaminated, what do you do with that knowledge? You can compare your findings against the DEQ standards for agricultural use. Also, HUD and the City of Portland's Building Department have guidelines. But you have to be able in the end to look your neighbor in the eye and say, “Yes, this site is safe for use.”

* * *

Debrief: Mr. Henry provided some very useful information, which I am sure is greatly appreciated. Three things stand out: first, that pollution of the urban environment is a widespread and serious problem; secondly, that functioning in the urban environment therefore involves intelligently managing the risk from urban pollution; and thirdly, that providing sustainable and viable local economic systems – especially, local systems of food production – in urban areas will require us to learn to live differently. If we care about relocalizing our food, we will have to stop polluting our land, and we will have to stop supporting those businesses and activities of the present official economy that continue to ruin our cities. I know there are cities in China and on the African continent that are learning this the hard way.

One other note: The City of Portland's Bureau of Planning and Sustainability is hosting its “Urban Growth Bounty 2010” series of classes on urban agriculture and self-sufficiency. There will be 82 classes, covering topics such as urban farming, keeping chickens and bees, food preservation, and cheesemaking. Those who live in Portland and who are interested can go to http://www.portlandonline.com/bps/ugb for class descriptions and online registration links.

Lastly, here are links to the organizations mentioned in this interview:

Saturday, January 16, 2010

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 8th 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:

Sunday, May 24, 2009

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:

Saturday, April 4, 2009

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 21st 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: