Why the U.S. Still Bleeds Horseshoe Crabs Despite a Lab-Made Alternative

The U.S. still relies heavily on horseshoe crab blood for endotoxin testing, despite a lab-made alternative widely used in Europe. Since the Covid era, the number bled annually has risen to about one million crabs, whose blood is used to produce LAL assays that detect bacterial toxins in medicines, vaccines, and devices. The alternative was added to the U.S. Pharmacopeia in 2025, yet adoption lags due to regulatory and industry inertia. Proponents argue the body of evidence supports non-animal methods, while critics cite supply chain, ecological concerns, and ethics as ongoing motivations to move faster.