Thursday, Florida governor and presidential candidate Ron DeSantis signed a bill that would allow roadways across the state to be constructed with “radioactive” mining waste linked to cancer.

The bill, introduced by the state House, adds phosphogypsum to a list of “recyclable materials” that state officials say may be utilized in road construction.

Officials had previously determined that pulverized rubber from car tires, ash residue from coal combustion byproducts, recycled mixed-plastic, glass, and construction steel are “part of the solid waste stream and contribute to the problem of shrinking landfill space.”

The partially depleted New Gypsum Stack South wastewater reservoir at Piney Point in Palmetto, Florida, on May 4, 2021, as seen from above. In March, the reservoir contained approximately 480 million gallons of water and was in danger of collapsing and flooding the surrounding area.

However, unlike the majority of these products, phosphogypsum is not an aggregated material in landfills. The EPA classifies it as “radioactive material” due to the “small amounts” of uranium and radium it contains.

Phosphate rock is mined to produce fertilizer, but the residual material, known as phosphogypsum, contains decaying traces of elements that produce radon.

This substance is known as a “potentially cancer-causing, radioactive gas,” an EPA representative previously told CBS News. Because of this risk, the federal government mandates that phosphogypsum be stored in gypstack systems, not landfills, to prevent it from coming into contact with humans and the environment.

“The Clean Air Act regulations require that phosphogypsum be managed in engineered stacks to limit public exposure from emissions of radon and other radionuclides in the material,” an EPA spokesperson told CBS News previously.

Before it can be used, the state’s Department of Transportation must conduct a study to “evaluate the suitability” of its use and “may consider any prior or ongoing studies of phosphogypsum’s road suitability in fulfillment of this duty.” This obligation must be fulfilled by April 1, 2024.

CBS News has reached out to DeSantis for comment on the signing of this bill, but he has not yet made a public statement.

Elise Bennett, director of Florida and the Caribbean for the Center for Biological Diversity and an attorney, stated in a statement that the measure is a “reckless handout to the fertilizer industry.”

Bennett stated that Gov. DeSantis is paving the way for generations of Floridians to deal with a noxious legacy. Under the guise of a so-called feasibility study that will not address grave health and safety concerns, this opens the door for radioactive waste to be deposited on roadways across the state.

Why is phosphogypsum so hazardous?

According to the EPA, radon, the gas emitted by phosphogypsum, is the second-leading cause of lung cancer, second only to smoking, and is linked to approximately 21,000 lung cancer fatalities annually in the United States. According to the agency, it is also the “single greatest environmental source of radiation exposure.”

Due to this risk, the EPA has prohibited the use of phosphogypsum in construction for decades. A spokesperson for the agency previously told CBS News that it is permitted for agricultural and indoor research, with restrictions, and that specific applications can be approved if the project “is at least as protective of human health as placement in a stack.”

Before phosphogypsum can be used in road construction, EPA approval is legally required, according to the agency. “Upon issuing any notice of pending approval, the EPA will open a public comment period, make any applications and our technical analysis of those applications publicly available, and seek input on the proposed decision.”

CBS News has reached out to the EPA for additional comment following the passage of the bill.

The History of phosphogypsum problems in Florida

In Florida, phosphate extraction has been a source of contention for decades. This issue was most recently seen in the controversy surrounding Piney Point, a former phosphate mining facility in Manatee County on the Gulf Coast, which, after several years of problems, had a nearly “catastrophic” breach in 2021 that resulted in 215 million gallons of water containing environmentally toxic levels of nutrients entering Tampa Bay within 10 days.

It was discovered to have contributed to a red tide event and a vast fish kill in the region in the months that followed. It prompted a lawsuit from the state’s Department of Environmental Protection and a $3 million cleanup allocation from Florida legislators.

Ragan Whitlock, a staff counsel at the Center for Biological Diversity, stated to CBS News upon the bill’s introduction that “history has shown that wherever this waste goes, environmental contamination follows.”

Several of the state’s 27 phosphate extraction facilities have experienced leaks, sinkholes, and other problems throughout their lifetimes. Over twenty organizations, including the Center for Biological Diversity, urged DeSantis to veto the bill in May.

Rachael Curran, an attorney with People for Protecting Peace River, wrote in a letter urging the governor’s decision, “No environmentally conscious or ‘green’ governor worth his salt would ever sign into law a bill approving roadbuilding with radioactive materials.”

Whitlock told CBS News that he has “very little confidence” in the state’s “ability to manage this project,” despite the state Department of Transportation’s promise to conduct a study or consider an existing one.

“The Florida Department of Transportation would conduct a feasibility study to determine whether or not this material is suitable for construction,” he explained. “The Florida Department of Transportation is unable to determine the safety and health of this product for Floridians and the environment.”