People could be unknowingly spreading “forever chemicals” on their lawns and gardens in the form of fertilizers sold across the country, including Milwaukee’s famed Milorganite.
A study by the Sierra Club and the Michigan-based Ecology Center found that Milorganite was one of several fertilizers that contain PFAS. All of the fertilizers are made of at least 50% biosolids — treated sewage sludge — rich in nutrients helpful in growing grass, fruits and vegetables.
MMSD has been selling Milorganite as a commercial fertilizer since 1926 in the United States and Canada, and on its website touts the product as “one of the nation’s oldest recycling efforts.”
Aside from Milorganite, eight other fertilizers were tested, and most were purchased at locations like Lowes and Menards, where most people access similar products. All of the products contained varying levels of PFAS, meaning that fruits and vegetables fertilized with the products may soak up the chemicals as they grow.
“PFAS in fertilizers could cause garden crops to be a source of exposure for home gardeners,” the report says.
Researchers recommended that at-home gardeners refrain from using biosolid-based fertilizers on their plants to minimize risk of exposure to the chemicals.
But the PFAS contained in the fertilizers aren’t only a problem for those growing their own fruits and vegetables. Experts said the PFAS found in wastewater treatment plants are likely coming from somewhere else, meaning that industrial users are still not properly filtering the harmful compounds out of their waste streams before releasing them into the wastewater system.
PFAS, or per- and polyfluoroalkyl substances, are a group of man-made chemicals used for their water- and stain-resistant qualities in products including clothing and carpet, nonstick cookware, packaging and firefighting foam.
The chemicals are persistent, remaining both in the environment and human body over time. Accumulation of the chemicals in the body has been linked to cancer, studies have shown, or other adverse health effects.
Researchers tested the fertilizers for 33 PFAS compounds, including two of the most well-known — PFOA and PFOS.
Included in the testing was:
- ProCare Natural Fertilizer, purchased at Lowes, made of 85% to 91% biosolids sourced from multiple locations in Georgia.
- EcoScraps Slow Release Fertilizer, purchased at Home Depot, made of 100% biosolids from unknown sources.
- Milorganite 6-4-0 Fertilizer, purchased at Home Depot, made of 100% biosolids from the Milwaukee Metropolitan Sewerage District.
- Cured Bloom Soil Conditioner, purchased at a store in Washington D.C., made of 100% biosolids from the Blue Plains Advanced Wastewater Treatment Plant in Washington D.C.
- Menards Premium Natural Fertilizer, purchased at Menards, made of 100% biosolids from unknown sources.
- GreenEdge Slow Release Fertilizer, purchased at Home Depot, made of 100% biosolids from JEA sewer collection system in Jacksonville, Florida.
- Earthlife Natural Fertilizer, purchased at a store in Eliot Maine, made of 100% biosolids from New England Fertilizer Company in Quincy, Massachusetts.
- Synagro Granulite Fertilizer Pellets, purchased in Sacramento, California, made of 100% biosolids from the Sacramento Regional Wastewater Treatment Plant
- TAGRO Mix, purchased at Ace Hardware, made of 50% biosolids from Central Wastewater Treatment Plant in Tacoma, Washington.
The study compared the fertilizers to Maine standards for PFAS in biosolids, the state with the most robust action for the chemicals in biosolids, the document noted.
“These ‘forever chemicals’ were found in all of the nine products tested by the Ecology Center of Michigan and Sierra Club and marketed as ‘eco’ or ‘natural’ and eight of the nine exceeded screening levels set by the state of Maine,” the report says.
Wisconsin currently only has recommended standards for some PFAS compounds in ground, surface and drinking waters, determined by the state Department of Health. Lawmakers have yet to pass legislation on the chemicals in water, and no action has yet been taken on limits for biosolids in the state.
Tom Nowicki, a staff attorney for MMSD, said that just because PFAS were found in Milorganite doesn’t mean there is a risk to users.
“The fact that they’re in biosolids is not a surprise,” he said. “The question that needs to be answered is how much causes a risk, and there are studies underway to measure the transport of PFAS in biosolids.”
This isn’t the first study to raise concerns over the level of PFAS in Milorganite.
In 2019, Maine and Massachusetts raised questions over the fertilizer’s levels of perfluorinated chemicals. Maine stopped sales of the fertilizer for a period of time until testing confirmed that PFAS levels were low enough to meet the state’s new standards.
No states currently ban Milorganite, MMSD officials said.
Since then, Vermont, New Hampshire and Michigan have also begun to test biosolids for PFAS, according to the study, and Colorado has implemented PFAS standards that will likely lead to permit restrictions for industrial sources of the chemicals. Testing biosolids is important because not only are they put into fertilizers, they’re also routinely spread on agricultural land, including crops and grass that cows graze on.
PFAS have shown up in biosolids in Wisconsin before.
In Marinette, biosolids from the city’s wastewater treatment center that were spread on fields was found to have contaminated the wells of some farm homes. The findings pushed the DNR to further test wells in an expanded area of farmland.
The Marinette-Peshtigo area has one of the worst PFAS contaminations in the state, due to years of outdoor testing of firefighting foam containing the chemicals. The foam was produced by Tyco Fire Products, a subsidiary of Johnson Controls, and sprayed on concrete during testing before being washed down sewer drains.
In 2019, the DNR asked operators of 125 wastewater treatment plants, including MMSD, to test for more than 30 PFAS compounds in their sludge. In metro Milwaukee, the request also went to the City of Brookfield, Fredonia, Grafton, Hartford, Jackson, Saukville, South Milwaukee, Waukesha and West Bend, since the DNR said these communities are more likely to receive wastewater from businesses that knowingly or unknowingly use PFAS.
Solution starts with industry
There are ways to make sure that “forever chemicals” don’t end up in the fertilizers that people use on their gardens, though.
The study suggested a number of solutions, including more thorough testing of water discharged by industrial users to treatment plants and cutting down on the use of biosolid-based fertilizers. But the most important steps to regulate chemicals in the biosolids would be legislation at the state and national levels.
Gillian Miller, a senior scientist with the Michigan-based Ecology Center, said she hopes the study spurs action by state legislators across the country to enact regulations for how much of the chemicals are allowed to be found in sludge and water. Getting wastewater treatment plants to test the water flowing out of the facility for PFAS and try to find the source of PFAS “up the river.”
The action shouldn’t be left with regular people, though, she said.
“This is a global problem,” Miller said. “Making choices at the consumer level won’t stop this.”
Nowicki, of MMSD, also hopes that the study will spur action in Wisconsin to regulate upstream industrial use of the chemicals. MMSD is only a passive recipient of the chemicals, he said, and is not generating the issue.
“The way to solve the problem is to stop it from getting into the economy in the first place,” he said. “We support people talking to their legislators and trying to get action at that level to get this stuff out of products.”
Sonya Lunder, a senior toxics policy advisor for the Sierra Club, said that right now without legislation, the burden is being placed on everyday people to chose different fertilizers or figure out how to deal with PFAS already in their soil or water. But that shouldn’t be the case, and if governments adopt some of the suggestions in the report, that could be a good first step.
“People are really just being stuck with exposure,” she said. “And these solutions aren’t just for one agency. Multiple things will need to happen to contain this crisis.”