Environmental advocates have long raised alarm about the environmental hazards created by the fertilizer production process, including phosphogypsum, a byproduct of the fertilizer production. Phosphogypsum is stored permanently in large mounds, often called stacks or gypstacks, away from the public because of longstanding health concerns over its radioactive qualities.

But approval of Mosaic’s pilot project has prompted concern that phosphogypsum could soon be used in road construction in the United States for the first time in history — and that Florida could be first in line. The study has already garnered support from the Florida Department of Transportation and Gov. Ron DeSantis, who signed a bill in June 2023 to allow the use of phosphogypsum in road construction. That issue has already led to one law suit, filed Tuesday, against the EPA.

“The project allows the industry and the EPA to circumvent the risk analysis in several ways,” said Ragan Whitlock, an attorney with the Center for Biological Diversity. “The EPA is directly contradicting its own science and regulations by tripling the permitted cancer risk to the public and ignoring key radiation pathways.

The Mosaic Co. argues that current storage practices create an even larger environmental hazard than their proposal to incorporate phosphogypsum into road construction instead, according to the project proposal submitted to the EPA in March 2022.

“We continue to believe decisions like this need to follow the science, and EPA did just that,” Mosaic Co. Spokeswoman Ashleigh Gallant said. “The agency’s review was detailed and methodical, and two very different administrations came to the same conclusion – that PG can have a useful purpose other than stacking.  EPA’s approval requires safeguards to protect people and the environment. It’s disappointing that CBD once again ignores the science.”

Mosaic Co. project studies possibility of building roads with phosphogypsum

The EPA specifically approved construction of a small-scale pilot project that will take place in the confines of the Mosaic Co.’s New Wales facility in Polk County. The study will be conducted in conjunction with researchers from the University of Florida, and will examine whether the waste product can safely be used as part of a mixture of materials for road foundations.

The EPA approved a request submitted by the Mosaic Fertilizer, LLC, in December to build four sections of test road that vary in mixtures of phosphogypsum, each 500 feet long and 24 feet wide, on property that already contains gypstacks.

The project is meant to test the environmental impact of its use as part of a road base mixture. Under the clean air act the EPA requires fertilizer production companies, such as Mosaic, to dispose of phosphogypsum in gypstacks to protect the public from exposure to its radioactive components.

In its approval notice, the EPA stated that the radiological risks associated with the study meet the same regulatory requirements for storing phosphogypsum in stacks because of the location of the project — clearing a path for the project to proceed without increased risk of public exposure.

“Local communities have expressed a desire for beneficial reuse of PG (phosphogypsum) for generating economic development, making land available for other uses and mitigating aesthetic and potential environmental concerns,” he wrote. “Meanwhile, (phosphogypsum) is widely and safely used in other countries, with significant safe reuse reported in at least 21 countries.”

Mosaic claims phosphogypsum is safe to use as a road base

Mosaic does not view the use of phosphogypsum in roads as a new financial venture, but seeks a way to recycle the material for a beneficial purpose, company spokeswoman Jackie Barron told the Herald-Tribune. The company will partner with University of Florida researcher Dr. Timothy Townsend on the test efforts.

None of the four test road sections will consist of more than 50% phosphogypsum, and they will be compared with four control sections of road that will be built onsite without phosphogypsum. Mosaic is also required to inform all workers involved with construction of the road that phosphogypsum contains elevated levels of radionuclides and instruct them about the proper protection prior to working on the project.

“The radium in phosphogypsum (comes) from the ground,” Barron said. “It is part of the phosphate rock under our feet right now, removed during the mining process in order to create a critical crop nutrient for the more than 50% of farmers across North America who rely on Florida phosphate.”

“The impacts to human health and the environment are the primary focus of that analysis,” she said. “We welcome robust testing. We want people to know this is a safe and worthwhile resource, not a waste, and we are decades behind others who long ago realized just that.”

The project will likely begin this spring. Mosaic must complete necessary environmental sampling for a minimum of 18 months and submit data to the EPA no more than 60 days after being generated. The company must submit a final report to the EPA within 90 days of testing completion, records show.

“We believe there is great value in the principles of a circular economy whereby materials formerly viewed as wastes can be used or recycled beneficially,” Barron said. Phosphogypsum “has value in the right circumstances, and we expect the results of the road trial to reflect that.”

Research into the use of phosphogypsum as road base material continues in Florida

Townsend is at the Herbert Wertheim College of Engineering, a research unit at UF in Gainesville. He and his graduate students have collaborated on research into the potential use of phosphogypsum as a part of road base material for years. He said a full-scale pilot project is the next step in the scientific process.

“We did a series of tests in the laboratory over a number of years, and the results suggest that if a road is built the right way and is built properly then it falls within typical accepted thresholds of what normally we look at when we recycle materials into applications like this,” Townsend said.

“So at one point we suggested at the university that a really important, helpful next step, would be to go actually build it,” he said. “Take it outside of the laboratory but build it on a pilot scale, because that would allow more data to be gained but that would give everybody a better understanding and more comfort with the process.”

The University of Miami conducted a project in cooperation with county public works departments and the Florida Department of Transportation in the 1980s, before the EPA established regulations on phosphogypsum.

Researchers built a 1.5-mile road, called Parrish Road, a mile east of Fort Meade in in Polk County in 1986. The project also included construction of another experimental road in Columbia County, a two-mile rural road known as White Springs Road in 1987.

That study reported no adverse environmental impacts were found following completion of groundwater monitoring studies, but did identify some levels of impact attributed to the roads that were deemed to be within acceptable drinking water standards. Still the EPA banned the use of phosphogypsum waste in 1989, except in specific instances where the waste has very little radioactivity, according to the EPA website.

Townsend said the new Mosaic study is meant to further the scientific understanding of phosphogypsum, and that the experiment will adhere to scientific best practices that determine whether materials are harmful to human or environmental health.

“Yes, it’s a sensitive subject,” Townsend said. “But we are trying to collect the data to allow people to make informed educated decisions.

“Phosphogypsum, like most waste materials, has things in it that if you don’t manage it the right way could be a concern,” Townsend said. “What we are doing, we are trying to get more science and data to allow not only Mosaic, but the EPA and FDOT and local governments and the general public, to get some understanding of does it work and does it pose a risk or not?”

Environmental advocates wary of where Mosaic Co.’s roadway may lead

Environmental advocates who for decades have raised concern about the negative environmental impacts created by the fertilizer industry say the study is a sham, and is only a step in a plan to find a less expensive way for Mosaic to dispose of its ever growing piles of phosphogypsum.

“This project has been designed by the industry and will be carried out by the industry to reach an intended result,” the Center for Biological Diversity’s Whitlock said.

Compton sees the study as the latest attempt to find a less expensive way to dispose of the hazardous waste produced in the process of making fertilizer. He instead calls for the industry to find cleaner ways to produce it.

“If you have the widespread use of phosphogypsum in roadways you are basically spreading hazardous waste around with little oversight,” Compton said. “The ultimate solution is not to produce it in the first place. They should come up with a methodology that doesn’t produce phosphogypsum, so that residents of the state of Florida don’t have to worry about their waste.”

INFOGRAPHIC: What is phosphogypsum?

Fertilizer production companies such as Mosaic Co. create a hazardous waste called phosphogypsum as part of their operations. The waste is heavily regulated and must be permanently stored and maintained in stacks on company property. The Mosaic Co. has proposed a plan to use the material as a road base instead. Here is where phosphogypsum comes from:

Phosphate found underground in Florida has to be treated to be used as a fertilizer that plans can use. After the mineral is scooped from underground, the rock is separated from sand and clay.

It is mixed with sulfuric acid to create phosphoric acid, which is used to to create usable fertilizer at chemical plants concentrated in central Florida.

A result of the chemical process called calcium sulfate, or gypsum, is also produced. The industrial byproduct is known as phosphogypsum. Approximately five tons of phosphogypsum are made for every ton of phosphoric acid….

The EPA requires that the phosphogypsum remain in stacks in perpetuity without creating negative impact to the environment. As the phosphogypsum dries out, a crust forms on the stack. The crust thickens over time, reducing the amount of radon that can escape and helping keep the waste from blowing in the wind. Some of the water can leak out the bottom and pollute local groundwater.

Some stacks cover hundreds of acres and are hundreds of feet high.

Sources: Florida Industrial and Phosphate Research Institute/Florida Polytechnic Institute and the U.S. Environmental Protection Agency.