In a stunning example of the interconnected nature—and vulnerability—of the U.S. food system, the recall of one product by an Iowa company has led to 27 companies needing to review whether their products should be recalled, according to Food Safety News.

Garner, Iowa-based Aspen Hills manufactures cookie dough, and the Aspen Hills recall has already led to four other companies issuing their own recalls. More recalls could follow.

Blue Bell Creameries discovered Listeria monocytogenes in the cookie dough that came from Aspen Hills during product testing at one of its production plants in September, resulting in the recall of two flavors sold to the public and three sold to foodservice accounts.

Aspen Hills followed up with a voluntary recall of some of its cookie dough this past Sunday, although the company said it did not find Listeria in the company’s cookie dough. A spokesman said the company did uncover “food safety issues” such as inadequate documentation and failure to wear proper uniforms, which could potentially contribute to contamination. These findings spurred the Aspen Hills recall.

Only the 27 food manufacturing companies who used Aspen Hills’ cookie dough in their products between July 15 and Sept. 30 received the company’s recall notice. To date, Blue Bell, Blue Bunny, Chocolate Shoppe and Publix have issued ice cream recalls.

According to a press release from Blue Bell, the recall is voluntary and no illnesses have been reported. “Although our products in the marketplace have passed our test and hold program, which requires that finished product samples from a batch test negative for Listeria monocytogenes before the batch can be released, Blue Bell is initiating this recall out of an abundance of caution,” the company said.

Although no illnesses have been reported, Blue Bell is particularly cautious about any possibility of Listeria contamination because in 2015 three deaths were linked to Blue Bell products contaminated by the bacteria. The U.S. Centers for Disease Control and Prevention estimate Listeria causes about 1,600 illnesses and 260 deaths in the U.S. every year, particularly in young children, the elderly or people with weakened immune systems.