Consumer Reports is urging General Mills to reduce plastic chemicals in its pre-packaged foods.

In a letter sent Wednesday to General Mills, the advocacy group said it found “concerning” levels of phthalates in several General Mills products, including Annie’s Organic Cheesy Ravioli. Other General Mills products that tested positive for high levels of chemicals include Yoplait Original Low Fat Yogurt, Cheerios Original and Green Giant Cream Style Sweet Corn, according to Consumer Reports.

“When you buy organic, the last thing you’d expect is that you would be eating plastic chemicals,” Consumer Reports Food Policy Director Brian Ronholm said in a statement. 

General Mills did not immediately respond to a request for comment.

Phthalates, also known as plasticizers, are chemicals that can be used to make plastics more durable and flexible, according to the Centers for Disease Control and Prevention. Some studies have linked the chemicals to adverse health outcomes such as heart disease, diabetes and obesity. 

Consumer Reports also launched a petition on Wednesday calling on General Mills and its subsidiary, Annie’s, to eliminate plasticizers from their products. 

The organization in January published a report listing the plastic chemical contents of more than 80 popular snacks and other pre-prepared foods. The study found that 99% of supermarket and fast foods contain phthalates, while 79% contain traces of another potentially harmful substance called bisphenol A.

“In a recent test of a wide variety of foods, Consumer Reports found plasticizers in every food product at very high levels, including several General Mills products,” the group said in its February 7 letter to General Mills CEO Jeffrey Harmening. 

“Because of the number of ways that plasticizers can enter our food supply, we recognize that these chemicals cannot be completely avoided,” Consumer Reports add. “However, our test results revealed that some products had much lower levels compared to others. This demonstrates that, even though these chemicals are ubiquitous in food, it is possible to reduce their presence, and consumers expect the industry to achieve these lower levels.”