Is your big box store selling you soil contaminated with PFAS?
Many of us who grow our own food, whether we’re gardeners or homesteaders, know that we can produce healthier, fresher and more delicious food outside of the corporate food system.
However, the prevalence of PFAS—the “forever chemicals” that have been linked to various cancers, fertility issues and behavioral changes in kids—challenges even the simple act of growing one’s own garden.
Slick marketing and the ubiquity of misleading “eco friendly” products at big box and local gardening supply stores could lead to unwitting contamination in your home garden. Here are a few tips to help you reduce the risk to your plants and soil.
PFAS (per- and polyfluoroalkyl substances) are a large family of chemicals with extremely strong carbon-fluorine bonds that are virtually impossible to break. They can accumulate in soil and water and be absorbed by plants and other living organisms in a process called “bioaccumulation.” Different PFAS behave differently in soil and plants, but if they are present in your garden’s soil they are likely making it into your produce and onto your family’s plates.
According to an article from the Green Policy Institute, long-chain PFAS, such as PFOS and PFOA, are less likely to be found in the leafy, above-ground portion of vegetables. These larger molecules tend to stay in the soil and are less mobile within plants. However, smaller-chain PFAS, like PFBS, are more water-soluble and have higher bioavailability, meaning they can travel more easily throughout the plant, including edible greens. This can make leafy greens more susceptible to PFAS uptake than grains or fruit. In a 2018 study, researchers from the Minnesota Department of Health examined several home gardens and found that “floret” vegetables like cauliflower and broccoli showed the highest levels of PFAS accumulation compared to other garden vegetables, indicating that these types of plants may absorb more of these harmful chemicals.
But PFAS uptake in plants is highly variable and depends on many factors including soil types, plant species, rainfall, available organic matter and the chemical properties of the PFAS compounds present.
Actions you can take to limit your exposure if you are unsure of the PFAS in your soil include adding compost to your garden, which can reduce PFAS uptake in plants, and peeling root vegetables such as carrots before eating them, as these chemicals tend to concentrate in the outer layers of the vegetable.
Sludge from public wastewater treatment facilities contains PFAS, so steer clear of these sources to help protect your garden and health.
Many bagged “compost” and fertilizer products are marketed to gardeners with misleading labels that can be difficult to decipher, and which often hide the fact that they are made with PFAS-contaminated sludge from public wastewater treatment plants.
Industries flush PFAS-containing waste down drains that flow to sewage treatment plants. These plants accumulate both industrial and residential waste to keep the waste from going straight into our surface waters. Yet the anaerobic treatment process cannot remove chemicals like PFAS, many of which settle in byproduct of treatment, a solid material, known as sludge, that is separated from the liquid during treatment.
Private corporations are then contracted by wastewater treatment plants to dispose of the sludge. These corporations attempt to convince farmers to accept this sludge as “fertilizer” for their fields, and in the process end up poisoning their fields. Waste companies also will “compost” that sludge and package it for retail sale to gardeners for use in home gardens.
A Sierra Club study from 2021 identified at least 30 different commercial fertilizers made from sewage sludge and sold at retailers like Lowe’s, The Home Depot, Ace Hardware and Menards.
Many bear terms like “eco,” “natural” or “organic” on the label despite the fact that sewage sludge, also called “biosolids,” are not allowed to be applied on farms growing certified organic fruits or vegetables. The Environmental Protection Agency regulates pathogens and heavy metals in sludge but does not set limits on other chemical contaminants like PFAS. Of the products marketed to home gardeners tested by Sierra Club, most contained 100% sludge, but none bore any warnings about the content of PFAS or other chemical contaminants. Maine is one of the few states that have set limits on PFAS in sludge-derived products. The Sierra Club study showed that eight of the nine fertilizers tested exceeded screening limits for PFOS or PFOA in Maine.
For a longer list of bagged products for garden use that contain sewage sludge see here.
Another resource identifying garden products containing sludge, from the Institute for Agriculture and Trade Policy, can be found here.
According to the National Organic Program (NOP), the regulatory framework that defines organic in the U.S., sludge or sludge-derived products are banned from certified organic food production. This does not mean that every time you find a bagged fertilizer in the store labelled “organic” it is safe for use. The products could claim to improve “organic matter” in your garden or be good for “organics” without meeting the federal definition of organic. One way to be sure that a product was produced using no sludge, is to look for the Organic Materials Review Institute (OMRI) seal. OMRI is a third-party certifier that ensures that the product was produced according to the standards of the NOP.
The most important thing you can do is to read the listed ingredients. If it lists “biosolids,” then it almost certainly contains PFAS. If “compost” is listed as an ingredient without explaining where that compost comes from, then be skeptical. “Compost” made from sewage sludge is toxic to land and people, but compost made from real organic material is nourishing. If a label doesn’t say what it is made from, then the best advice would be to avoid it.
Pesticides can also contain PFAS. Choose Certified Organic or OMRI certified pesticides, or better yet, use beneficial insects, physical barriers or biological products like insecticide soaps and other pest-reducing techniques used in organic agriculture.
By growing our own food, we have the chance to produce food outside of a corporate system that puts us at odds with natural processes, and we have a chance to re-enforce the abundance of the natural world. As we learn about the prevalence of PFAS in gardening products and our daily lives, we are seeing how nature’s abundance is being poisoned by corporate profiteering, making it more difficult to produce healthy food for ourselves and family. By turning back to organic principles and products, we can undo some of this harm, heal ourselves, our backyards and our planet.
Bill Pluecker has been farming commercially since 2005. Bill is the Public Policy Organizer for Maine Organic Farmers and Gardeners Association (MOFGA), where he works to engage the community to take action in support of clean soil and water, with an emphasis on addressing PFAS contamination of farmland and building awareness and advocacy on this topic across the country. Bill has served in the Maine Legislature since 2018. He represents House District 44 (the towns of Hope, Union and Warren) and serves as House Chair of the Agriculture, Conservation and Forestry Committee. He currently runs Begin Again Farm, a small vegetable operation selling primarily wholesale to local groceries and the Mainers Feeding Mainers program.
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