Two Colorado residents have filed a lawsuit against cannabis producer LivWell for using a pesticide, they say, is unsafe for cannabis cultivation.

The pesticide, Eagle 20 EW, is used to protect crops from pests like mildew, but isn’t specifically approved by Colorado for products, such as cannabis or tobacco, that are ignited and inhaled.

Eagle 20 contains myclobutanil, a chemical that, when burned, produces hydrogen cyanide gas. The gas can, in large doses, lead to lung injury, convulsions and fatal respiratory failure.

The plaintiffs are looking for regulators to penalize LivWell for using the chemical on their cannabis crops.

LivWell has stated their products are safe.

Since legalization was introduced, the case is the first cannabis liability claim in the U.S..