Florida has announced plans to test an unconventional road-building material: phosphogypsum, a radioactive byproduct of phosphate mining.
The decision has sparked both optimism and concern as experts weigh potential economic benefits against public health risks.
What is phosphogypsum?
Phosphogypsum is a waste product created during the production of phosphorus, an essential nutrient in fertilizers.
To extract phosphorus, phosphate rock is dissolved in acid. This process separates uranium, which ends up in the acid, and radium, which remains in the remaining material. The remaining waste is called phosphogypsum.
Radium naturally breaks down over time and releases radon gas. Radon is a radioactive gas that is known to increase the risk of lung cancer when people are exposed to it for long periods of time.
Because of these risks, federal regulations require that phosphogypsum be stored in specially designed structures called technical stacks.
These stacks are huge, often hundreds of feet high, spanning large areas and resembling small mountains. The purpose of these piles is to contain the radioactive material and limit human exposure to ensure public safety.
Green light for radioactive road surface
Earlier this week, the Environmental Protection Agency (EPA) approved a pilot project by Mosaic, the largest phosphate producer in the United States.
The project involves the construction of four test road sections at the New Wales Mosaic Plant in Polk County, Florida, using phosphogypsum as the road base.
The EPA described the project's risks as “low” based on several modeling efforts. However, approval is limited to this specific initiative. Any broader applications would require additional assessments and regulatory approvals.
Health risks of radon exposure
Radon, an odorless and colorless gas, poses significant health risks in elevated concentrations.
According to the Center for Biological Diversity, it is the second leading cause of lung cancer in the United States, causing about 21,000 deaths annually. Prolonged exposure, particularly near roads composed of phosphogypsum, could raise public health concerns.
Because of these risks, federal regulators have banned phosphogypsum in construction in the past.
In 1992, the EPA highlighted potential hazards to construction workers and future residents living near roads containing phosphogypsum. Exceptions exist for controlled agricultural and research purposes.
Use of radioactive materials on roads
Critics argue that the EPA's approval prioritizes industry interests over public safety. Florida has had problems with phosphogypsum in the past.
In 2021, a rupture at a former phosphate mining site released 215 million gallons of toxic water into Tampa Bay, causing environmental and health crises.
“This dramatically increases the potential for harm to our road crews and water quality,” said Ragan Whitlock, an attorney with the Center for Biological Diversity. He accused the EPA of giving in to political pressure from the phosphate industry.
Environmentalists also emphasize the long-term effects of using radioactive material in infrastructure. Concerns include radon exposure to road workers and communities living near phosphogypsum roads, as well as possible contamination of water sources.
Economic potential of phosphogypsum in road construction
Proponents of phosphogypsum-based roads see economic potential.
Jackie Barron, a representative for Mosaic, emphasized the cost benefits of using phosphogypsum compared to traditional materials such as limestone.
“If there is an alternative use for this material and we don't have to unnecessarily grow or manage these piles, then why wouldn't we go that route?” Barron said in a 2023 interview with NPR.
Regulatory and political uncertainty
Florida passed a law last year to expand the list of materials allowed in public road construction. However, the state Department of Transportation still needs to review the suitability of phosphogypsum before its widespread adoption.
The issue has undergone political changes. The Trump administration approved the use of phosphogypsum on roads, but the Biden administration later reversed that decision.
It remains unclear how the new government will handle the future of the material.
Road construction and radioactive waste
While Mosaic's pilot could pave the way for innovative recycling, it also highlights the need for careful risk assessment.
The debate over phosphogypsum highlights the broader challenge of balancing economic benefits with environmental and public health concerns.
Florida's experiment will likely serve as a critical case study for the rest of the country. Whether it's a breakthrough or a misstep, the outcome will have lasting impacts on road construction and radioactive waste management.
Information for this article comes from an EPA press release.
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