While much of the world struggles to clean up contamination from the toxic industrial compound PFOS, Brazil is still adding to the massive environmental mess with its large-scale production, use, and export of sulfluramid, a pesticide that degrades into PFOS.

Linked to low birth weight, weakened immune response, liver effects, high cholesterol, thyroid dysfunction, cancer, and other health problems, PFOS is no longer made or used in most countries. The chemical, which was phased out in the U.S. by 2015, was originally developed by 3M and was a critical component of Scotchgard and firefighting foam. In the 182 countries that are party to the Stockholm Convention, an international treaty (unsigned by the U.S.) that governs persistent pollutants, the use of PFOS has been severely restricted since 2009.

But the Stockholm Convention carved out several loopholes for PFOS, including one for its use in killing leaf-cutting ants. Sulfluramid is made from PFOS and breaks down into that and several other chemicals within weeks. Brazil, the only country governed by the treaty that has permission to produce the pesticide, has been able to export it without notifying the convention because the treaty restricts PFOS, but makes no mention of sulfluramid, which is now used widely in Uruguay, Brazil, Argentina, Paraguay, Colombia, and Venezuela, among other countries.

This week, delegates of the Stockholm Convention are meeting in Geneva to discuss whether to close loopholes in the PFOS ban. Environmentalists are pushing to name sulfluramid in the treaty, which would require Brazil to report its sales outside the country and to put a five-year limit on the loophole allowing its use to kill leaf-cutting ants.

Pesticide makers from Brazil are expected to push back. Abraisca, a trade association representing the main manufacturers of the pesticide in Brazil, insists that sulfluramid is necessary “to ensure the safety of people and the environment.” While green organizations point out that there are ways to kill leaf-cutting ants that don’t involve creating persistent toxic waste, the industry group has argued that there are no effective alternatives to sulfluramid. Abraisca did not respond to requests for comment.