When First Lady Michelle Obama decided to plant a vegetable garden at the White House, she faced a problem that many new homeowners in America run into. Previous residents of her house had applied sewage sludge [3] to her lawn, but left no warnings to alert the her about the potential toxicity of her soil as a result of the sludge application. When the Obamas tested the soil in preparation for planting their garden, they found some lead in the soil. At 93 parts per million (ppm), the lead showed that the soil was probably contaminated by something, even though at 93 ppm the lead itself was not necessarily a danger. Still, the Obamas took precautions to further lower the lead level to 14ppm, and make the lead unavailable to plants by adding soil amendments that diluted the lead and changed the pH of the soil.

Sludge Politicized

Unfortunately for the Obamas, and for the entire nation, once the story hit the news, it became politicized. While the issue was initially raised as a comment on the safety of using sewage sludge as fertilizer – an issue that has no political party – the right soon grabbed a hold of the story as a way to make fun of the Obamas. Some on the left fiercely defended the Obamas in return. But the Obamas are not the villains in this story; they are the victims. They are among many other Americans whose yards and gardens are contaminated with sewage sludge without their knowledge and who, as a result, are exposed to toxic contaminants in the soil. And lead is just a fraction of the overall problem.

When it was conceived, the White House garden was intended as a symbol of support for home gardening and fresh, organic food. In fact, famed chef and visionary Alice Waters [4] lobbied for the White House garden for more than a decade. When it finally became a reality last year, she said, "Fresh, wholesome food is the right of every American. This garden symbolizes the Obamas' commitment to that belief." But in planting her garden, Michelle Obama not only set the example she intended for home gardening, she also illustrated why using sewage sludge as fertilizer is so harmful.

How the White House Got Sludged

To the best of anyone's knowledge, the White House garden was first sludged in the Reagan years [5]. During the 1980's, the nation was experiencing the aftermath of the Clean Water Act, which required wastewater treatment plants to remove toxins from wastewater before releasing the water into the environment as effluent. As a result, wastewater treatment plants across the country were left with sewage sludge, a grey jelly comprised of everything they removed from the water. Some cities -- most notably New York City -- dealt with sludge by dumping it in the ocean, a practice that environmental groups were working to end. As this played out in court in the 1980's, New York searched for a new way to dispose of sludge. Ocean dumping was finally banned by the Ocean Dumping Reform Act of 1988, a law that fully took effect in 1991.

There is no really "good way" to dispose of sludge. Recent EPA data [6] shows that the majority of sludge samples tested contained a list from A to Z of toxins including metals, pharmaceuticals, flame retardants, semivolatile organics, polycyclic aromatic hydrocarbons, and steroids. Sludge may also include other substances (or organisms) that the EPA did not test for, including parasites, bacteria, viruses, dioxins, and pesticides. Yet today, wastewater treatment plants and even the EPA talk about "beneficial uses" for sludge: converting it to energy (while releasing pollutants into the air), using it as alternate daily cover in landfills, or spreading it on farmland, gardens and lawns as fertilizer.

Sludge PR

The language around sludge (and even the name of sludge itself) changed as wastewater treatment plants across the country looked for ways to dispose of sludge when ocean dumping was no longer an option. New York City shopped their sludge around, looking for a community that would welcome it as fertilizer. Understandably, nobody wanted it. For obvious reasons, sludge is a public relations [7] nightmare, even before people understand the volume and variety of toxins it contains. It was in this environment, as the issue played out during the Reagan and Bush years, that the National Park Service [8] began applying sludge at the White House.

Sludging the White House was but one part of the campaign to clean up sludge's public image. In the waning days of the first Bush administration, the sewage industry trade, lobby, and public relations group, the Water Environment Federation [9] (WEF), held a contest among its members to rename sludge. The EPA liked the new name they selected – "biosolids [10]" – so much, they gave WEF a $300,000 grant to promote the "beneficial use" of sludge. The EPA also modified its rules governing the application of sludge on America's farmland, which previously classified sludge as hazardous waste. With its nifty new name, "biosolids" now qualified as fertilizer – so long as it met some minimal requirements. Specifically, the EPA regulates the amounts of only nine heavy metals and fecal coliform bacteria that are permitted in sludge that is applied to land as fertilizer. And, while keeping high levels of lead, arsenic, and other heavy metals out of sludge is a nice gesture, compare that to the long list of chemicals and organisms that sludge may actually still contain.

What's In That Stuff, Anyway?

Sewage sludge is not only a mix of everything that goes down household drains, it also contains industrial and hospital waste. The root of the problem is our sewer system, which uses water as a means to transport waste and does not separate what goes down toilets or kitchen sinks from what goes down the drain at oil refineries, factories, or other industrial sites. Instead of forcing industry to bear the cost of disposing of its waste products responsibly, we let them send it to our wastewater treatment plants, mixed in with water, and taxpayers bear the cost of separating that waste out from the water and then dealing with it as sludge. Therefore, the contents of sludge are determined by the materials disposed of by nearby industrial sites (although some chemicals are more or less universal in all sludge, based on the EPA's tests).

It's Not Sludge, It's "Biosolids"!

Despite this, the EPA continued promoting the "beneficial use" of biosolids and the National Park Service continued applying it at the White House until as late as 2004 [11]. In the rest of the country, home gardeners could buy sludge for their own lawns or gardens in commercially marketed fertilizers like Milorganite [12] (sludge from Milwaukee, marketed using the slogan "For Better Results. Naturally."), Hou-Actinite (sludge from Houston, marketed as "a naturally nutrient rich slow release organic fertilizer"), Allgro (which promises to help you "fertilize organically – while promoting environmental sustainability among American businesses"), and Vital Cycle (marketed as "a concentrated natural organic fertilizer"). Companies marketing sludge as fertilizer frame their products as natural, sustainable, and even organic, terms that are misleading and and dangerous. In fact, the USDA's organic standards specifically forbids applying sewage sludge to land that is farmed organically [13], and making any claim that sludge is organic is just plain wrong.

What's In Your Soil?

If, like Michelle Obama, a gardener moves to a new house that was previously owned by someone else, or builds a new house on land that was previously farmland, the gardener will have no way of knowing what contaminants are in the soil if the previous owner has applied sludge. Garden stores sell soil test kits, but those only test for pH and a few key nutrients (nitrogen, phosphorus, and potassium). University labs often offer more extensive soil testing for a low price ($10-$30 or so), and those can include tests for lead, cadmium, nickel, chromium, and a few other heavy metals. However, it is impossible for the average gardener to find an inexpensive soil test kit that could even begin to identify the long list of contaminants that may be in soil "fertilized" with sludge. Also, commonly-available tests may not be sensitive enough to detect small amounts of contaminants that may only be present in parts per million or parts per billion. (Depending on the substance, a tiny concentration may be enough to harm one's health.)

Sludge Isn't Harmless

Despite the EPA's claims of safety, sludge has not been used as fertilizer for decades without incident. People and animals have become ill or died, and farms have gone out of business due to land application of sludge. Harry Dobin, who ran a coffee truck one thousand feet from a sludge composting site, was one such casualty. He began experiencing health problems in 1991, when he was 25 years old. After months of worsening symptoms and a number of wrong diagnoses, doctors discovered Aspergillus fumigatus, a fungus common in composting sludge, in his lungs. By the time he was diagnosed, the disease was too advanced to treat. Dobin died nine months after he was diagnosed, on September 23, 1992.

In a more recent example, Andy McElmurray spread sludge on his Georgia dairy farm for more than a decade [14]. The sludge fertilized crops fed to his cattle. All went well until he switched the crop he was growing and added lime to raise the pH of his soil in order to do so. The higher pH caused a toxic metal – molybdenum – to become bioavailable to the plants. The cows were poisoned by molybdenum, and many died. Ultimately, McElmurray went out of business. Even consumers are at risk, so long as farms use sludge as fertilizer. In McElmurray's case, a nearby NutraSweet factory had been sending thallium (used in rat poison) down its drains and it wound up in the sludge he applied to his land. When milk from a local grocery store was tested, it contained thallium at 11 times the legal limit for thallium in drinking water.

Michelle's Opportunity

It is truly a shame that Michelle Obama's vegetable garden is marred by past use of sewage sludge on the White House grounds. The historic garden has inspired many, both at home and abroad, and the First Lady is credited as one reason for a national surge in home gardening. It is not her fault that previous administrations were dishonest about the safety of sewage sludge as fertilizer, but now that she has uncovered the problem, she has the power and high-profile to do something about it to help other Americans. We hope she does.