Horseshoe Crab Blood Alternatives Will Be More Available for Vaccine Testing

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A horseshoe crab.
Source: Encyclopædia Britannica, Inc.

Horseshoe crabs have been around for 450 million years, meaning they are older than dinosaurs and survived the Ice Age. And, since the 1970s, the crabs’ bright blue blood has been used to test vaccines.

NPR journalist Chiara Eisner explains that the “blue blood of the horseshoe crab clots when it comes into contact with bacterial toxins, which helps technicians identify contaminated products. A synthetic alternative to the blood-derived testing ingredient, called limulus amoebocyte lysate, or LAL, was invented decades ago. Alternatives have since become mainstream; most of the east coast bleeding companies now also sell tests made with a synthetic, not just LAL, and the European Pharmacopoeia considered the synthetic ingredient equivalent to the crab-derived one in 2020. But since scientists at the U.S. Pharmacopeia [USP] had not yet done the same, drug companies that wanted to use them faced extra regulatory hurdles in the U.S.”

Now, thanks to changes being made by the USP Microbiology Expert Committee, pharmaceutical companies will have better access to the synthetic alternatives, all of which are non-animal derived

Beyond concern for the horseshoe crab itself, the crab plays an important part in coastal ecology. The crabs’ shell houses sponges, mud crabs, mussels, and snails. And, among other animals, red knots, a coastal migratory bird, eat horseshoe crab eggs. Without access to the rich fuel of the eggs, the birds have declined 94% since the early 1980s. 

1. Should pharmaceutical companies use the synthetic alternatives to horseshoe crab blood? Why or why not?

2. Should any medicines use animal products for testing? Why or why not?

3. How do you weigh the importance of medical advancement that relies on animal testing and the protection of animals? Explain your answer.

Chiara Eisner, “Vaccines Are Still Tested With Horseshoe Crab Blood. The Industry Is Finally Changing,”, Sep. 23, 2023

Katie Pavid, “Horseshoe Crab Blood: The Miracle Vaccine Ingredient That’s Saved Millions of Lives,”, Jan. 15, 2021

U.S. Pharmacopeia, “Expert Committee Proposes Chapter for Endotoxin Testing Using Non-Animal Derived Reagents,”, Aug. 22, 2023