Newly discovered PFAS concentrations in certain fertilizers could mean accumulation of the toxic chemicals in composts and home gardens, unbeknownst to gardeners, according to a new report from the Sierra Club and the Ann Arbor-based Ecology Center of Michigan.
The environmental groups had two commercial labs in Michigan test common fertilizers for 33 toxic contaminants known as per- and polyfluoroalkyl substances (PFAS). The so-called “forever chemicals” are manmade substances that are known to be harmful to human health, and have been linked to serious diseases, including cancer.
Each of the nine fertilizers tested contained between 14 to 20 of 33 detectable PFAS compounds.
“Michigan has gone farther than other states in dealing with the toxic legacy of PFAS contamination, [but] unfortunately, these chemicals are so persistent and so widespread that they are literally accumulating in our own human waste,” said Christy McGillivray, political and legislative director at Sierra Club Michigan.
“This shows that until we get PFAS off the market we aren’t going to be able to guarantee that it is not in our food supply. The profits of chemical companies are being prioritized over public health, and we must demand that state and federal agencies halt all uses of PFAS with limited exceptions,” McGillivray added.
The PFAS found in the fertilizers originate from sludge and biosolids used to make the product. Sewage sludge is any residue removed during wastewater or sewage treatments, and biosolids are sewage sludges treated for land application.
The total concentrations of the chemicals tested ranged from 38 to 233 parts per billion (ppb). Michigan has strict drinking water standards in place for seven PFAS chemicals as of last year, but proposed screening levels for biosolid fertilizers have not yet been adopted by the Department of Environment, Great Lakes and Energy (EGLE). All seven of those chemicals regulated in drinking water were detected in at least one fertilizer product.
Although a comparison between drinking water standards to sludge fertilizer is not a fully illustrative one, as fertilizers are dry solids and water is water, Ecology Center senior scientist Gillian Z. Miller said that two PFAS chemicals found in the biosolid fertilizer products (PFOA and (PFOS) were at least a thousand times higher than the state’s drinking water limits.
A more accurate comparison, Miller said, would be to note that “fish tissue in PFAS-contaminated waters has been found to have roughly similar levels of PFAS as the products we tested in this study.”
The report warns that the findings provide only a small snapshot of the wide-ranging presence of PFAS in wastewater systems in Michigan and elsewhere.
Many of the fertilizers, despite containing PFAS, are marketed as “eco” or “natural.” The full list of fertilizers tested includes: Cured BLOOM Soil Conditioner, TAGRO Mix, Milorganite 6-4-0 Fertilizer, Pro Care All Natural Fertilizer, Ecoscraps Slow Release Fertilizer, Menards Premium Natural Fertilizer, GreenEdge Slow Release Fertilizer, Earthlife Natural Fertilizer and Synagro Granulite Fertilizer Pellets.
Each was purchased at Lowes, Home Depot, Menards, Ace Hardware and other home improvement or plant stores across eight states and Washington, D.C.
The products were tested for eight perfluoroalkyl sulfonates (PFSAs), which are often used in firefighting foam and in metal plating; 11 perfluoroalkyl carboxylates (PFCAs); four PFAS ethers, seven perfluoroalkane sulfonamides (FASAs and related), often used in the process of making surfactants and surface treatments; and three fluorotelomer sulfonic acids (FTSAs), which can be found in leachate from wastewater treatment plants and landfills.
Only eight of the 33 chemicals tested for were not detected in any of the fertilizers. Cured BLOOM contained the most PFAS compounds.
To ensure buyers do not unwittingly purchase fertilizers containing PFAS, they should check that the “guaranteed analysis” product label does not contain terms like “biosolids,” “residuals” or “municipal waste.”
“We recommend gardeners not use biosolid-based fertilizers for their home gardens. No one knows exact health implications from consuming produce that has taken up PFAS from the soil, but we do know PFAS from such products do get taken up into plants and thus could pose health risks,” Miller said.
But a workaround to the issue is much more challenging for the complex commercial food supply as a whole — and the EPA does not require screening for PFAS in biosolids before land applications.
The agency is studying further action on the issue, but the process for establishing new EPA standards is slow. The Sierra Club and Ecology Center advise that states should not wait until national standards are set before implementing their own.
“We are urging governments to tackle the problem upstream — long before PFAS waste gets into soil amendments,” Miller said. “That means cleaning up industrial sources so that PFAS waste doesn’t go down the drain, and it means working toward eliminating all but unavoidable uses of PFAS in consumer products.”