Editor’s note: This story has been updated with a statement from Whataburger that was sent after publication.

A statewide environmental organization wants Texas retailers to stop using styrofoam plastic products and will spend the summer trying to make that happen.

Environment Texas, an environmental advocacy organization based in Austin, begins a campaign Tuesday that will target plastic pollution, mostly polystyrene or styrofoam, across the state.

The group is focused on food companies that serve styrofoam take-out cups, bowls, and containers and its first major target is the fast-food chain Whataburger. Environment Texas will hold a rally in front of Whataburger’s corporate headquarters in San Antonio on Tuesday in an effort to convince the chain to stop using styrofoam in its stores.

“They’re definitely a major contributor to the problem,” said Luke Metzger, executive director of Environment Texas. “They’re an iconic Texas chain and people love them. With that love comes some expectation that they’ll do the right thing.”

The biggest culprit is Whataburger’s iconic drink cups, which are made from styrofoam.

“At Whataburger we’re always looking for the best way to serve our customers,” according to a statement from Whataburger Corporate Communications. “We’re continuously researching new products and we’re currently looking at cup alternatives that keep drinks at the right temperature. We know our customers have come to expect high quality standards from us and will share any updates when we have news to share.

“Our Styrofoam cups are recyclable and we encourage everyone to dispose of them properly.”

Metzger wrote a letter in May to Preston Atkinson, president and chief executive officer of Whataburger, requesting an opportunity to discuss the environmental issues related to styrofoam waste.

He wrote that Americans dispose of 70 million plastic foam cups daily with one third ending up in waterways. Plastics don’t biodegrade in water like paper, food, or other organic materials do, Metzger wrote, and instead act as pollutants to marine life.

“Rather, they’ll remain intact or break down into smaller pieces called microplastics, creating a toxic plastic ‘soup’ that’s easily ingested by marine life,” Metzger wrote. “Plastic fragments have been found ingested by literally hundreds of different species, including 86% of all sea turtle species, and nearly half of all seabird and marine mammal species.”

Atkinson did not respond to the letter, Metzger said.

While the organization describes polystyrene as “one of the worst and most common types of plastic”, the group also wants to lobby State legislators to repeal a 1993 preemption against local plastic bans.

Last week, the Texas Supreme Court struck down a ruling that prohibited local governments from creating plastic bag bans. Consequently, a statewide preemption on plastic bans means municipal governments may not currently pass ordinances outlawing the use of materials like styrofoam.

Although Metzger says it will be “tough” to convince legislators to remove a state law prohibiting local ordinances on plastic bans, he sees hope in this upcoming legislative session.

Metzger said Environment Texas’ movement has spurred companies such as McDonald’s and Dunkin’ Donuts to pledge to stop using styrofoam and plastic bags and he hopes the positive change continues.

“I think we do have some momentum here,” Metzger said.