Here's what you should know about Milorganite and a recent study showing it may contain 'forever chemicals'

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Laura Schulte Milwaukee Journal Sentinel Published 9:00 am CT Jun. 7, 2021

A recent study by environmental groups found that you may be unknowingly spreading "forever chemicals" on your lawn and garden in the form of fertilizer.

And that sounds scary, especially because one of the fertilizers tested was Milwaukee's own famed Milorganite.

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.

Here's what you should know about Milorganite, the study and what should be done:

What is Milorganite?

Milorganite — the name is derived from Milwaukee organic nitrogen — is composed of heat-dried microbes that digest the organic material in wastewater, manufactured by the Milwaukee Metropolitan Sewerage District, according to milorganite.com. MMSD captures wastewater flowing into it and uses naturally occurring microbes to digest the nutrients commonly found in waste, like nitrogen, phosphorus and potassium.

After the organic material has been consumed, the clean water is then returned to Lake Michigan, and the resulting material is dried and sold as fertilizer.

Why do people like it?

Users typically prefer Milorganite because it's seen as an organic fertilizer. According to the company, the fertilizer works with nature and can help to build healthy soil.

Where is it made?

Milorganite is made in Milwaukee by MMSD. The sewerage district provides services for about 1.1 million people across 28 communities in the Milwaukee area.

MMSD has produced the fertilizer since 1926 and sells it across the U.S. and in Canada. It's touted as "one of the nation's oldest recycling efforts."

What did the Sierra Club study find about fertilizer?

The study, which was done by both the Sierra Club and the Michigan-based Ecology Center, found that several fertilizers purchased nationwide contained PFAS. All of the fertilizers contained at least 50% biosolids.

The study tested nine common fertilizers:

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.

What are PFAS?

PFAS, known as "forever chemicals" are per- and polyfluoroalkyl substances. They're 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.

Are there PFAS in Milorganite?

Yes, some PFAS were found in the popular fertilizer. PFOA and PFOS, two of the most well-researched forms of the chemicals, were both detected.

PFOA was detected at 0.67 parts per billion, under 2.5 parts per billion limit for the chemical in Maine, which was used as the standard for the study because it has the strictest requirements for PFAS in biosolids.

PFOS, however, was detected at 8.66 parts per billion in Milorganite, over the 5.2 parts per billion standard set by Maine.

The study found that some precursors to PFAS were contained in the Milwaukee fertilizer as well, which degrade over time to form actual PFAS.

The tests performed on the fertilizer checked for 33 common PFAS compounds, as well as precursor compounds and synthetic fluorine compounds.

Where did the PFAS come from?

To be clear, MMSD is not creating PFAS. The chemicals are coming from the waste stream, likely released as a byproduct of manufacturing. The district is currently encouraging state leaders to set standards for the chemicals so that discharges of PFAS to wastewater treatment plants are regulated to lower levels.

Tom Nowicki, staff attorney for MMSD, said the fact that the chemicals were found in Milorganite isn't surprising. He said that the biggest question to be answered after the results of this study is what levels of PFAS in fertilizer are unsafe. Studies are underway, he said, to look at the transport of PFAS from biosolids.

Are there any states in which Milorganite can't be sold?

No states have prohibitions against Milorganite, said Nowicki, not even Maine.

Other than Maine, 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.

What should I do to fertilize my lawn or garden?

While the study suggests that backyard gardeners should find a new fertilizer without biosolids, MMSD insists that Milorganite is safe to use.

"We need to remember that presence doesn't mean a risk from something," Nowicki said.

If you decide that biosolid-based fertilizers aren't something you want to use, check the "Guaranteed Analysis" label on the back of the bag. Terms like "residuals" or "municipal waste" typically indicate that biosolids are present in the product at some level.

How could we get PFAS out of wastewater and biosolids?

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.

Researchers also hope that the fertilizer study will spur more action by state legislators across the country.

Sonya Lunder, a senior toxics policy adviser for the Sierra Club, said without legislation, the burden is being placed on everyday people to choose 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."

Laura Schulte can be reached at [email protected] and on Twitter at @SchulteLaura.

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