It's already being sold in restaurants and supermarkets in the US. However, the results of a rat feeding study commissioned by Impossible Foods and carried out with SLH suggest that the burger may not be safe to eat. Rats fed the GM yeast-derived SLH developed unexplained changes in weight gain, changes in the blood that can indicate the onset of inflammation or kidney disease, and possible signs of anemia. The he FDA issued a "no questions" letter which is not an assertion by the FDA that the food is safe, but that the company is responsible for the safety of the food. The FDA does not protect consumers. In addition to GMO-derived SLH, the burger now contains GM protein from herbicide-tolerant soy and may contain residues of the "probable carcinogen" glyphosate pesticide. An advocacy group tested Impossible Burger and found that it had 11 times the amount of glyphosate when compared to Beyond Meat, which is a non-GM product.

The Impossible Burger is a plant-based burger, the key ingredient of which is a protein called soy leghemoglobin (SLH for short), derived from genetically modified (GM) yeast. It's already being sold in restaurants and supermarkets in the US. In 2019 the manufacturing company, Impossible Foods, applied for permission to market the burger in the EU and the UK.

However, the results of a rat feeding study commissioned by Impossible Foods and carried out with SLH suggest that the burger may not be safe to eat.