Sewage Sludge Rules Fail to Protect Health
By Cat Lazaroff
WASHINGTON, DC, July 3, 2002 (ENS) - The U.S. Environmental Protection Agency (EPA) is using outdated science to set standards governing the use of treated sewage sludge as a fertilizer, warns a new report from the National Academies' National Research Council. The committee that wrote the report is calling for additional studies to assess the health risks of sewage sludge.
Sewage sludge, the byproduct of treating municipal and industrial wastewater, is often used as fertilizer. But even treated sewage sludge may contain toxic chemicals such as polychlorinated biphenyls (PCBs), lead and mercury that can cause serious illnesses, including cancer and birth defects.
Treated sewage sludge may be causing health problems for workers who apply it to land and for residents who live nearby, suggests the new report from the National Research Council (NRC). More rigorous enforcement of existing standards is needed as well, says the NRC committee.
"There is a serious lack of health related information about populations exposed to treated sewage sludge," said committee chair Thomas Burke, professor, department of health policy and management at Johns Hopkins University Bloomberg School of Public Health in Baltimore. "To ensure public health protection, EPA should investigate allegations of adverse health effects and update the science behind its chemical and pathogen standards."
Under a 1993 Clean Water Act rule designed to protect public health and the environment, sewage sludge can be applied to land if it is treated to limit concentrations of certain toxic chemicals and reduce disease causing pathogens. Sewage sludge that meets these standards is referred to as biosolids.
Depending on the extent of treatment, biosolids may be applied as a fertilizer where there is limited public exposure to it, such as farms and forests, or on sites with more public contact such as parks, golf courses, lawns and home gardens. Since 1992, when a ban on ocean dumping was instituted, biosolids have been applied to land to reduce the amount of sewage sludge that must be buried in landfills or incinerated.
About 5.6 million tons of sewage sludge are used or disposed of each year in the United States, and 60 percent of that is used as fertilizer on land.
The NRC report, produced at the request of the EPA, is the latest warning in a series of studies that illustrate that spreading sludge on land may harm human health. In 1997, the Cornell Waste Management Institute's "Case For Caution" warned that the current rules do not appear to protect human health or environmental health, or to increase agricultural productivity.
In 2000, the Center for Disease Control identified one type of sewage sludge as a potential hazard for workers who handle this material, and earlier this year the Sierra Club released a guidance document critical of the current land application rules.
Two recent EPA Inspector General reports stated that the agency could not assure the public that land application protects human health and the environment, because there is not enough data or enforcement.
In a peer reviewed research paper on the risk of sludge pathogens, published in the July 1 issue of the journal "Environmental Science and Technology," EPA microbiologist Dr. David Lewis hypothesized that human sludge illnesses are caused by complex pathogen-chemical interactions that occur on land application sites.
"Sludge contains pathogens and a mixture of chemicals that can facilitate the infection process," wrote Lewis. His paper is available online at: http://pubs.acs.org/subscribe/journals/esthag-a/36/i13/pdf/702lewis.pdf
Methods for assessing the health risks posed by exposure to chemicals have evolved substantially since the 1993 biosolids rule was established, the NRC committee found. The EPA used an unreliable 1988 survey to identify hazardous chemicals in sewage sludge when it set the standards, and other chemicals have since been found to be of potential concern, the report warns.
The committee supported the EPA's general approach for reducing disease causing pathogens in biosolids, which mandate treatment of sewage sludge and restrictions on the uses of land after biosolids are applied. But the agency should use new pathogen detection technology to ensure that treatments are reliable, the report notes, and should step up efforts to enforce its biosolids rules.
For example, in certain cases, biosolids can be applied to land with the understanding that the land cannot be used for a specified period of time, to allow pathogens to fall below detectable levels. However, the EPA has not been verifying if pathogens are dying off, whether the land is being used for agriculture or grazing, or whether public access is adequately restricted.
Field data are needed in these cases, the committee said.
The EPA should develop microbial risk assessments to cover the possibility of disease transmission through person to person contact or through food, air or water that comes in contact with treated lands, the committee said. The agency should also begin a new national survey of what pathogens are found in sewage sludge, similar to a recent EPA survey that looked at chemical risks.
To assure the public that biosolids regulations are being followed, the EPA should increase its efforts to ensure that companies producing biosolids meet the regulatory requirements to remove or neutralize chemicals and pathogens, the committee recommended.
The committee also recommended that the EPA study the potential health risks to workers and residential populations exposed to biosolids. The report cites anecdotal reports linking biosolids to adverse health effects, ranging from mild allergic reactions to more severe chronic conditions, along with public concern about those reports.
Earlier this year, Synagro, the nation's largest sludge producer, paid a Greenland, New Hampshire family an undisclosed amount of money to settle a wrongful death suit - the first payment to an alleged victim of sludge induced sickness.
Critics of sewage sludge use applauded the NRC report, and called on the EPA to take immediate steps to reduce risks from biosolids.
"This should be a wake up call for those who have been pooh poohing the ways sewage sludge harms people's health," said Doris Cellarius, chair of the Sierra Club sewage sludge task force. "We hope the EPA will inform communities about the dangers of sewage sludge and create tougher standards to protect our air, drinking water and health."
Earlier this year, the EPA and the Natural Resources Defense Council (NRDC) reached a legal settlement that requires the agency to develop a plan to address concerns about biosolids.
"The Environmental Protection Agency needs to wake up and address a very unglamorous but critical public health problem - sludge," said Nancy Stoner, director of NRDC's clean water project. "The agency's current approach of spreading it around is not safe."
The National Sludge Alliance, a coalition of grassroots organizations, is calling for an immediate ban on the land application of sewage sludge, with the support of several families who say sludge is responsible for their illnesses.
"When my children were exposed to sludge they developed respiratory problems. After my 11 year old rode his dirt bike through a sludged field, he suffered severe vomiting and diarrhea and had to be taken to a hospital," said Florida resident Mari Hollingworth. "I want the spreading of sludge banned immediately."
The NRC report, "Biosolids Applied to Land: Advancing Standards and Practices," is available at: http://www.nap.edu