Florida put radioactive fertiliser waste beneath a private road; 4 test sections are being monitored for safety

A waste material from fertiliser production is being tested for a new use in road construction in Florida. The material, known as phosphogypsum, is produced when phosphate ore is processed to make phosphoric acid. It contains radium, which can decay into radioactive radon gas, so its use is regulated by the US Environmental Protection Agency. The EPA generally requires phosphogypsum to be managed in engineered stacks that limit public exposure. However, some other uses can be approved when they provide at least as much protection.According to the US Environmental Protection Agency, one such project in New Wales, Florida, uses phosphogypsum in the road base beneath asphalt on private property. The agency determined that the project was as protective of human health as stacking the material.How will the Florida road project be monitored for safetyThe EPA approved a phosphogypsum road construction project for Mosaic Fertilizer, LLC on December 23, 2024. The project is located on private property in New Wales, Florida. Phosphogypsum will be incorporated into the road base and covered with asphalt. The test road has four sections containing phosphogypsum in the road base, separated by four control sections without phosphogypsum.One upgradient monitoring well and two downgradient wells will be placed in each section. The property has controlled access, so members of the public are not expected to come into contact with the phosphogypsum in the test road. The EPA approved the request after determining that the proposed use was as protective of human health as placement of phosphogypsum in a stack.Why is the material considered a radiation and health concernPhosphogypsum is produced when phosphate ore is processed to make phosphoric acid, which is later used in fertilizer. The phosphate ore and the resulting phosphogypsum contain radium. Radium decays to form radon gas, which is radioactive and can cause cancer.The EPA says radon in outside air can enter structures and reach levels that pose a health hazard over time. Higher exposure to radon over prolonged periods can increase the risk of developing lung cancer. Phosphogypsum stacks also contain low-pH process water and heavy metals. Because radionuclides in phosphogypsum are a source of radon gas and direct gamma radiation, the EPA regulates phosphogypsum as a source category of radionuclides under the Clean Air Act.How are stacks designed to limit exposureEPA regulations generally require phosphogypsum to be managed in engineered stacks to limit public exposure from radon emissions. Owners and operators of inactive stacks must measure and report radon emissions and keep those emissions within regulatory limits. When phosphogypsum is placed on a stack, it is added as a liquid slurry.As the stack dewaters, the liquid effluent is captured, treated, tested, and discharged under the Clean Water Act. Newer stacks contain a liner to help prevent effluent from being released directly into soil and groundwater, while older stacks may not. When inactive, an engineered cover is typically placed over the phosphogypsum to prevent further water infiltration.Other uses of phosphogypsum under EPA rulesEPA regulations allow phosphogypsum to be removed from stacks for outdoor agricultural purposes and indoor research and development under certain conditions and restrictions. Any other use requires prior EPA approval formally. The agency evaluates each proposed use case by case, considering how the phosphogypsum would be used, the amount involved, and possible health risks to workers and the public, including risks from handling and transportation. EPA can approve a proposed use only when it is at least as protective of public health as placing phosphogypsum in a stack.You use AI every day. Now get your AI Quotient. Take the AIQ test.