By Marcelle Dibrell

The consequences of a 2021 EPA decision are now being felt by pool professionals who have long relied on sodium bromide for pool and spa treatment. What began as a quiet regulatory update is now changing the way these products are labeled, distributed, and applied — prompting many to ask if sodium bromide has effectively been banned.

The answer is no — but it’s now restricted. Sodium bromide may only be used in indoor pools, spas, or covered outdoor spas under current EPA rules.

A Closer Look at the Regulation In April 2021, the U. S. Environmental Protection Agency issued an Interim Registration Review Decision for inorganic halides, including sodium bromide. This decision, which flew under the radar for many, is just now surfacing as product labels are updated to reflect new limitations.

The key concern centers on bromate, a byproduct that can form when sodium bromide reacts with oxidizers like ozone or chlorine — especially in the presence of sunlight. The EPA has identified bromate as a probable human carcinogen linked to

In 2021 the EPA identified bromate as a probable human carcinogen linked to kidney and thyroid tumors in animal studies. Bromate is a byproduct when sodium bromide reacts with chlorine or ozone in the presence of sunlight. kidney and thyroid tumors in animal studies.

Because the risk of bromate formation is significantly higher in outdoor, UV-exposed environments, sodium bromide is now barred from use in outdoor swimming pools. Its application is restricted to indoor pools, indoor spas, and covered outdoor hot tubs.

Industry Voices Supporting the Restriction

For years, several water treatment experts have warned about the risks of bromate formation. Orenda Technologies discourages the use of sodium bromide entirely, citing its tendency to consume chlorine, persist indefinitely in pool water, and convert into harmful byproducts like bromates. They promote proactive, conflict-free chemical treatment methods.

The Environmental Working Group (EWG) has echoed similar concerns, citing studies showing that brominetreated pools may produce more toxic disinfection byproducts than chlorinated ones — raising the risk of DNA and cell damage for swimmers.

Meanwhile, Canadian regulators have implemented their own sodium bromide restrictions. Health Canada prohibits its use in systems involving electrolysis, ozonation, or UV treatment, and disallows products combining sodium bromide with potassium monopersulfate (MPS), due to thyroid risk concerns.

Pushback from Industry Stakeholders

However, not everyone agrees the science supports such sweeping limitations.

United Chemical, a longtime supplier of sodium bromide-based algaecides, contends the EPA’s decision is based on “theoretical risk” drawn from laboratory conditions — not from real-world pool use. The company explains that bromine, which forms in treated real-world pools, is rapidly consumed by organic contaminants, as is the product’s intended purpose. Dangerous bromate levels, on the other hand, are more likely to occur in clean, oxidizer-rich water with little to no contaminant load — such as unused pools with ozone or UV systems. “There is no evidence of any pool operator or homeowner being exposed to unsafe levels of bromate due to the proper use of sodium bromide in swimming pools,” the company states. “This regulation is not based on evidence of harm, but rather on a theoretical possibility.”

United Chemical asserts that sodium bromide is not a sanitizer or disinfectant, but a targeted treatment for specific problems, like chlorineresistant algae, and their products are formulated with clear dosing instructions to avoid overuse or misuse. They suggest that the EPA’s action represents an overly cautious regulatory approach — an attempt to eliminate even hypothetical risk at the expense of a product that has decades of safe and effective use behind it.

While the company has updated its product labels to comply with the new EPA rules, it continues to advocate for a more practical, evidencebased assessment of sodium bromide risks.

Where Things Stand Now

The EPA allowed a multi-year transition period for manufacturers to update product labels. That window has now closed, and pool professionals are beginning to see revised packaging and restricted distribution. For example, the oncepopular product Brom Spa now reads: “This product is not for use in swimming pools.”

The changes have led to confusion among service technicians, with some mistakenly assuming sodium bromide has been banned outright. While the chemical remains legal, its use has been sharply curtailed in outdoor settings — forcing pool professionals to adjust treatment protocols or seek alternatives.

As this regulatory shift takes effect, those who’ve long used sodium bromide to combat stubborn algae or operate bromine-based systems are urged to consult new label instructions and reach out to manufacturers with questions.

More information is available in EPA document EPA- HQOPP-

chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/file:///Users/carolyndibrell/Downloads/EPA-HQ-OPP-2009-0168-0037_content.pdf

chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/file:///Users/carolyndibrell/Downloads/EPA-HQ-OPP-2009-0168-0037_content.pdf 2009-0168-0037.