The Environmental Protection Agency will let farmers and others use sewage sludge as fertilizer without concern for the amount of dioxins, a class of organic chemicals that the agency’s studies have shown pose a possible cancer risk in humans.
“We're deciding not to regulate dioxin in land-applied sludge that farmers use,” EPA spokeswoman Lisa Harrison said Friday, adding that the agency will instead “encourage proper management” of the chemicals.
About 5.6 million tons of sewage sludge is used or disposed of each year in the United States, including more than 3 million tons used as fertilizer on farms, forests, parks, golf courses, lawns and home gardens.
A National Research Council panel said last year the government was using outdated science to assess the health risks of the sewage sludge used as fertilizer.
However, Geoffrey Grubbs, who heads the EPA Office of Water’s science and technology program, said the decision to not regulate dioxin in land-applied sludge came after five years of peer-reviewed analysis and study.
“The risk of new cancer cases from this source is small, is substantially smaller than other chemicals we regulate,” Grubbs said. EPA also looked at the potential risks to wildlife and didn’t find “any significant impacts,” he said.
But he said the agency has worked hard to reduce people’s exposures to dioxins through stricter technology requirements for incinerators and cement kilns in the past 15 years.
EPA was due to issue a final rule Friday to regulate the amount of dioxins in sludge spread as sewage on land as part of a settlement agreement with the Natural Resources Defense Council, the environmental group said.
NRDC calls dioxins “among the most toxic substances on earth, and land-applied sewage sludge is the largest source of dioxin exposure in the United States after backyard barrel burning.”
Nancy Stoner, director of NRDC’s clean water project, said the problems extend well beyond farms.
“This is not about a farm product. This is about sewage sludge that comes out of large urban environments,” she said, adding that the group would now review EPA’s decision to see if more legal action is warranted.
Dispute over impact
The group said the settlement was meant to conclude lawsuits filed by NRDC and environmentalists in Oregon more than a decade ago in an attempt to force the agency to limit toxic pollutants in sludge.
NRDC said the Clean Water Act required the agency to limit toxic pollutants such as dioxins that may harm human health or the environment.
An EPA scientific advisory committee in 2001 reported that dioxins cause cancer in laboratory animals, and possibly in people — conclusions that had potential effects for everything from milk, beef and fish to medical, chemical and paper products.
But that committee had split over whether to change wording in a draft report from a year earlier that had said dioxins should be classified as a known human carcinogen.
Dioxins, or dioxin-like compounds, are pollutants found in air, soil and water, which can be released when industrial waste is burned. They build up in fatty tissues of animals, and scientists believe that humans are exposed to them when they eat animal fats. Breast-feeding infants and unborn children are at risk of suffering harmful effects like behavioral disorders and cancer if they are exposed to high levels.
The contaminant used in Agent Orange, a defoliant sprayed during the Vietnam War, included the most toxic form of dioxins.