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For Immediate Release


Sylvia Wu, 510-434-4871,

Press Release

Public Oral Argument in Lawsuit Challenging FDA Approval of Genetically Engineered Ingredient That Makes Impossible Burger 'Bleed'


Tomorrow, on Wednesday, April 14, the U.S. Court of Appeals for the Ninth Circuit will hear arguments in Center for Food Safety’s (CFS) ongoing lawsuit challenging the U.S. Food and Drug Administration’s (FDA) approval of soy leghemoglobin (a.k.a. “heme”), the novel genetically engineered (GE) color additive that makes Impossible Foods’ eponymous plant-based burger, the Impossible Burger, appear to “bleed” like real meat. CFS originally filed the lawsuit in March 2020, challenging FDA’s safety review of the genetically engineered color additive.  

At stake in tomorrow’s argument is whether FDA examined the safety of soy leghemoglobin as a color additive before allowing it to be consumed by millions of consumers across the U.S. In its briefs, CFS argued that FDA applied an unlawful safety standard, and approved soy leghemoglobin without long-term toxicity studies called for by the FDA under its standards for food and color additive testing. The outcome of the case could remove Impossible Foods’ plant-based burger products from grocery shelves until their safety for human consumption has been adequately reviewed.  

WHAT: Public oral argument in CFS’ lawsuit challenging FDA approval of soy leghemoglobin

WHEN: Wednesday, April 14, 2021, at 9 AM PST

WHERE: Ninth Circuit Court of Appeals YouTube Channel 


Soy leghemoglobin, the novel heme colorant used to make the Impossible Burger appear to “bleed,” is produced using GE yeast, and is modeled on a protein found in the roots of soybean. Because GE heme is new to the human diet, and substantial quantities are added to the Impossible Burger, FDA should have required extensive safety testing before approving its use as a color additive, as required by law.

While CFS like many others avidly supports plant-based eating, enthusiasm for meatless products cannot be used as an excuse to skirt food safety laws. Because color additives offer no substantive benefits, and add only aesthetic appeal, Congress and FDA established an extremely high bar for approval. The "convincing evidence" standard ("convincing evidence that establishes with reasonable certainty that no harm will result from the intended use of the color additive") means that a color additive cannot be approved without the strongest possible evidence of safety, a higher bar than for other food additives. 

CFS' lawsuit asserts that FDA used a lower safety standard than “convincing evidence” when it reviewed and approved GE heme to be used in raw Impossible Burgers sold in grocery stores. The lawsuit further alleges that Impossible Burger failed to submit long-term animal feeding studies for cancer, reproductive impairment and other adverse effects, which are required by FDA’s Redbook, the “Bible” of food and color additive testing. This lack of testing is all the more troubling because a number of potential adverse effects were detected in a short-term rat trial: disruption of reproductive cycles and reduced uterine weights in females, and biomarkers of anemia, reduced clotting ability, and kidney problems.


Center for Food Safety logo

Center for Food Safety's mission is to empower people, support farmers, and protect the earth from the harmful impacts of industrial agriculture. Through groundbreaking legal, scientific, and grassroots action, we protect and promote your right to safe food and the environment. CFS's successful legal cases collectively represent a landmark body of case law on food and agricultural issues.

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