Whole Foods bills itself as “America’s healthiest grocery store,” but what it’s doing to the environment is anything but healthy. According to a new report, the chain is helping to drive one of the nation’s worst human-made environmental disasters: the dead zone in the Gulf of Mexico.

By not requiring environmental safeguards from its meat suppliers, the world’s largest natural and organic foods supermarket — and most of its big-brand counterparts in the retail food industry, like McDonald’s, Subway and Target — are sourcing and selling meat from some of the worst polluters in agribusiness, including Tyson Foods and Cargill. The animal waste and fertilizer runoff from their industrial farms end up in the Gulf of Mexico, where each summer, a growing marine wasteland spreads for thousands of miles, leaving countless dead wildlife in its oxygen-depleted wake.

“The major meat producers like Tyson and Cargill that have consolidated control over the market have the leverage to dramatically improve the supply chain,” according to the report, which was released by Mighty Earth, an environmental action group based in Washington, DC.