Just received this important new story on EPA research on BSE prions in sewage sludge.
Preliminary EPA research showing the wastewater treatment process cannot remove from biosolids disease-causing proteins known as prions could complicate the treatment industry's push to dispose of biosolids through land application, rather than in landfills or by incineration, EPA scientists say.
The preliminary findings are part of research conducted by EPA's Office of Research & Development and regions V and VIII to determine the best disposal methods for animal carcasses infected with Chronic Wasting Disease (CWD), which is caused when the animals ingest prions found in the environment. CWD, which affects mainly deer and elk, is a type of transmissible spongiform encephalopathy (TSE). Other forms of TSE, including "mad cow disease," can affect sheep, mink, cows and humans. CWD has been found in 23 states and five EPA regions, EPA officials say.
EPA Region VIII researcher Wendy O'Brien said May 17 at EPA's 2005 Science Forum in Washington, DC, that preliminary results from the first phase of a two-phase study examining the fate of prions in wastewater treatment shows that prions can be found in treated effluent and biosolids, with biosolids containing most of them. O'Brien said the presence of prions in biosolids may be problematic for publicly owned treatment works (POTWs) because biosolids are sometimes used as fertilizer, which would reintroduce the prions into the environment.
Wastewater treatment industry officials did not return calls seeking comment.
The findings could complicate the wastewater treatment industry's continued push to allow POTWs to land-apply biosolids as a fertilizer as a less-costly alternative to incinerating them or transporting them to landfills. The industry has faced intense scrutiny for the practice in the past from environmentalists and food safety activists, who have said land application releases cancer-causing dioxins and has caused cows' deaths.
Specifically, the Center for Food Safety in 2003 filed a petition asking EPA to ban land application based on a Georgia court's finding that sludge application on one dairy farm caused the death of hundreds of cows, while the Natural Resources Defense Council has said in the past that EPA should regulate potentially cancer-causing dioxins in the sludge.
Although EPA later denied the petition and declined to regulate dioxin released through the practice, the agency has been reluctant to endorse land application over other disposal methods. The wastewater industry has asked for EPA endorsement of the practice to fend off lawsuits from environmentalists who oppose the practice.
But agency water chief Ben Grumbles said in an October 2004 letter that EPA would not "issue a statement favoring the beneficial reuse of biosolids over other uses [because] we do not believe that EPA should be involved in determining the biosolids management options most suitable for a particular community."
Last year, EPA issued an interim practices guidance on land disposal of prion-containing CWD-contaminated carcasses, outlining current best practices and noting that several western states and Wisconsin have relied on landfill disposal to deal with thousands of carcasses. The guidance recommends steps to minimize migration of water from the carcasses to surface waters and says it is preferable that the water be re-circulated and not discharged to a POTW or through a direct discharge permit.
Although EPA's interim practices guidance says the agency has no reason to believe the current practice of landfilling these carcasses is inappropriate, Susan Mooney, a landfill expert from Region V, said EPA is working to improve its knowledge base for recommending best practices by studying the fate and transport of prions in landfills.
S ource: Inside EPA via InsideEPA.com Date: May 20, 2005 Issue: Vol. 26, No. 20 (c) Inside Washington Publishers