Spring is planting time for farmers and home gardeners alike. They usually give their soil a dose of fertilizer to help their sprouts grow. For some, that might mean applying biosolids.
Biosolids are created from sewage sludge at wastewater treatment plants that has been treated to remove disease-causing pathogens and some pollutants. Hundreds of thousands of tons of it are produced annually at facilities across the Chesapeake Bay watershed and applied to cropland, pastures and gardens.
Those biosolids enrich the soil with nutrients and organic matter that feed plants.
But testing indicates that at least some biosolids could be delivering a side order of so-called “forever chemicals” that could be making their way into groundwater, streams and the food chain.
An environmental group recently reported detecting what it called “ultrahigh” levels of per– and polyfluoroalkyl substances, or PFAS, in biosolids produced by the Blue Plains Advanced Wastewater Treatment Plant in the District of Columbia.
DC Water, the utility that operates Blue Plains, sells it under the brand name, Bloom. Farmers in Maryland, DC, Virginia and Pennsylvania can buy it by the ton, while homeowners can purchase 25-pound bags at some home and garden stores.
“When I saw … these astronomically high levels of PFAS in this product, I was stunned,” said Tim Whitehouse, executive director of Public Employees for Environmental Responsibility, the group that tested Bloom.
PEER said a private lab analyzed the biosolids and found 21 parts per billion of perfluorooctanoic acid (PFOA) and 26 parts per billion of perfluorooctane sulfonate (PFOS). PFOA and PFOS are the two most frequently detected PFAS compounds.
DC Water acknowledges that there are PFAS in its biosolids, but Chris Peot, director of resource recovery, said its tests detected “considerably lower” levels of those compounds — no higher than 3.7 parts per billion of PFOA and 15.5 parts per billion of PFOS, according to the authority’s website.
“Their characterization of it being astronomically high, I think is unfair,” Peot said.
On its website, the utility says the overall PFAS levels detected in Bloom are many times lower than what has been measured in food packaging, ketchup, cosmetics and even daycare dust.
PFAS are a group of about 9,000 chemicals widely used in everything from fire-fighting foam to nonstick cookware, stain resistant and water repellant clothing, and some food packaging. They don’t break down readily and have been detected almost everywhere, including in drinking water, food and people.
Laboratory studies have linked chronic exposure to the chemicals to a variety of adverse health effects, including immune deficiencies, developmental problems and cancer.
The U.S. Environmental Protection Agency recently proposed enforceable nationwide limits in drinking water for PFOA, PFOS and four other PFAS compounds at 4 parts per trillion each.
Ten states, including New York and Pennsylvania, already have their own state limits on PFOA and PFOS. Delaware is in the process of regulating them.
But the EPA has not set any limits on PFAS in biosolids. While there is evidence PFAS can leach through soil into groundwater and that plants can absorb PFAS through their roots, scientists and regulators are still trying to understand to what degree biosolids might be involved. The EPA is evaluating whether the health and environmental risks posed by PFOA and PFOS in sewage sludge warrant regulation, but that assessment is not expected to be finished until the end of 2024.
Some states are not waiting, according to a recent report by the Environmental Council of States. Maine banned land application of all but a few types of biosolids in 2022 after testing found high PFAS levels in milk, grass and manure at a farm where biosolids had been applied. Michigan bars land application of biosolids if PFAS levels exceed 125 parts per billion and limits their use at levels down to 50 parts per billion. A few other states require monitoring at this point.
DC Water’s Peot said the high levels in the Maine farm soil likely resulted from past spreading of paper mill sludge there.
Blue Plains treats relatively little industrial waste by comparison, he pointed out, and the PFAS levels in its biosolids are low enough to be legally applied in Michigan.
In the Bay watershed, states are moving cautiously. The Maryland Department of the Environment has gotten about 30 municipal treatment plants so far to voluntarily test their wastewater and biosolids for PFAS. It expects to gather more data and is analyzing the results to determine what, if any, risks they pose.
In the meantime, MDE announced in February that it would stop issuing new permits for spreading biosolids on land until it completes its evaluation. That put a hold on eight new permits but did not apply to 242 current permits that allow biosolids be spread over 28,000 acres of land.
“We didn’t want new farms to start applying the material out of the utmost caution,” said Tyler Abbott, MDE’s director of land and materials. But a total ban on biosolids land application, he added, “would be a very large inconvenience,” not only for farmers forced to pay more for other fertilizer but also for treatment plants that rely on land application to dispose of much of their sewage sludge.
In Pennsylvania, the Department of Environmental Protection is working to add monitoring and reporting requirements to permits it issues for land application of biosolids, spokesman Jamar Thrasher said.
As with most other states, Virginia’s Department of Environmental Quality is waiting for the EPA’s risk assessment before imposing any limits, said Jeff Steers, director of regional operations. In the meantime, he said, the agency is telling wastewater plants in Virginia to check if there are any industrial or commercial sources of PFAS contamination among the facilities piping wastewater to them.
PEER’s Whitehouse said he was glad MDE had started to address biosolids in PFAS. He noted that the EPA has set extremely low limits on PFAS in drinking water and has said that there is no safe level of exposure to PFOA.
“It’s a huge problem,” Whitehouse said of biosolids contamination, “and people are going to have to figure out how to filter it out if it is going to be used on food crops.”
But DC Water’s Peot warned against “broad brush” decisions without further information.
“I’m all for studying this, I’m all for regulation,” Peot said in a webinar that DC Water held earlier this year. “I think it’s really important, but I implore regulators to ensure that their decisions are science-based.”
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