The state’s Marijuana Enforcement Division issued an advisory on Wednesday about potentially unsafe levels of microbials in batches of cannabis from Denver cultivator Sundance Gardens.

The Colorado Department of Public Health and Environment considers the contamination “a threat to public health and safety when marijuana is found to have levels of Total Yeast and Mold above the acceptable limits,” the division wrote.

In addition to the contaminated batches, the division noted several others that Sundance Gardens had not submitted for testing that were produced at the same time, between June 1 and July 17. The containers list the cultivation facility’s license number and the batch identification, which the division advised cannabis customers to check.

“Consumers who have these affected products in their possession should return them to the retail store from which they were purchased for proper disposal,” the division wrote. “Consumers who experience adverse health effects from consuming the product should seek medical attention immediately and report the event to the store from which they purchased the product.”

Jordan Tishler, a cannabis specialist in Massachusetts, noted in a 2018 article that in rare cases mold can cause hypersensitivity pneumonitis. In extreme cases, it is fatal, and symptoms include coughing, fever and shortness of breath.