In early 2014, blogger known as Food Babe launched a petition pushing sandwich chain Subway to remove an obscure chemical also used in yoga mats from its bread. Two days and more than 78,000 signatures later, Subway announced it was taking out azodicarbonamide — the yoga-mat chemical, as it came to be known.

Since then, a number of other major fast-food chains have followed suit, sans petition or fanfare.

McDonald's, Chick-fil-A, Wendy's, White Castle and Jack in the Box, which all used the chemical in their breads in 2014, have since gotten rid of it entirely.

“We removed these items because it was the right thing to do and it was a concern for our customers,” a McDonald's spokesperson said.

But the company didn't mention the bread additive's removal in a press release this week announcing several other ingredient overhauls, including the removal of high-fructose corn syrup from buns and artificial preservatives from McNuggets.

Azodicarbonamide is a commonly used dough conditioner that is also found in flip-flops and packing insulation, because it makes them both lighter and stronger, according to the Environmental Working Group, an advocacy organization. The Food and Drug Administration has approved its use in food in limited amounts, but the European Union has banned its use in food. The World Health Organization has linked it to asthma, and the industry watchdog group the Center for Science in the Public Interest has cited potential links to cancer, especially in high doses.

At Dunkin' Donuts, it's now out of the croissants and danishes, and while it's still in the Texas toast, a spokesperson said the chain is testing a new, azodicarbonamide-free version. At Burger King, the additive remains only in French toast sticks. At Arby's, it's out of all regular buns and breads and left in just the croissants, French toast sticks and sourdough breakfast bread.

“Good riddance,” said Michael Jacobson, executive director of CSPI, “but if you're thinking of health, it's only a tiny step forward.” He says sodium and calorie counts are bigger concerns.

McDonald's, Dunkin' Donuts, Wendy's and White Castle separately said they reformulated their breads in response to consumer preferences.

“I consider our brand a little more humble in terms of not patting ourselves on the back,” said White Castle spokesman Jamie Richardson.

Not everyone chalks up the lack of hoopla to humility. “They don't want to bring unnecessary attention to their ingredient decks,” said Vani Hari, the blogger whose petition prompted Subway to cut the chemical.