Some common garden fertilizers sold by major retailers have concerning levels of PFAS compounds, so-called “forever chemicals” that last in the environment for decades and potentially harm health, a new study has found.

The fertilizers in question contain biosolids — sewage sludge sold by wastewater treatment plants after it has been dried and treated for biological contaminants. But it’s often not treated for per- and polyfluoroalkyl substances — PFAS — compounds used in a host of commercial products for waterproofing and grease resistance, as well as in many industrial applications. The PFAS compounds have been tied to cancer and other health problems.

It’s not just a potential problem for those growing their own fruits and vegetables. The PFAS levels found in biosolids coming from wastewater treatment plants around the country point out the degree to which the chemicals continue to flow from industrial waste streams — and the lack of filtration at the factory or the wastewater treatment plant to remove the chemicals. The environmental nonprofits behind the study present Michigan as a model for other states to follow in identifying and requiring treatment from large industrial contributors of PFAS wastewater.

For their research, the Ann Arbor-based environmental nonprofit Ecology Center, along with the Sierra Club, purchased nine garden fertilizers from eight states and the District of Columbia, and sent it to a contracted laboratory for PFAS analysis:

• Pro Care All Natural Fertilizer, made up of 85.5% to 91.5% biosolids from an unknown source, purchased at Lowes
• Ecoscraps Slow Release Fertilizer, made up of 100% biosolids from an unknown source, purchased at Home Depot
• Milorganite 6-4-0 Fertilizer, made up of 100% biosolids from the Milwaukee Metropolitan Sewerage District, purchased at Home Depot
• Cured BLOOM Soil Conditioner, made up of 100% biosolids from DC Water’s Blue Plains Advanced Water Treatment Plant, purchased at W.S. Jenks & Sons in Washington
• Menards Premium Natural Fertilizer, made up of 100% biosolids from an unknown source
• GreenEdge Slow Release Fertilizer, made up of 100% biosolids from the JEA sewer collection system in Jacksonville, Florida, purchased at Home Depot
• Earthlife Natural Fertilizer, made up of 100% biosolids from the New England Fertilizer Co. of Quincy, Massachusetts; purchased at York Woods Tree & Products, Eliot, Maine
• Synagro Granulite Fertilizer Pellets, made up of 100% biosolids from Sacramento (California) Pelletizer
• TAGRO Mix, made up of 50% biosolids from the Tacoma Central Wastewater Treatment Plant in Washington, purchased at Ace Hardware.