Horseshoe crab blood contains molecules that clot in the presence of bacterial toxins, and extracts from that blood are used to test vaccines and injectable medicines for endotoxin contamination, providing a sensitive safety check before products reach patients.
What it is
Horseshoe crab blood is blue because it uses copper‑based hemocyanin rather than iron‑based hemoglobin, and a specialised component called amoebocyte lysate (LAL or TAL) reacts and clots when it encounters endotoxins from Gram‑negative bacteria.
How it is used
Pharmaceutical manufacturers use the LAL test to screen vaccines, injectable drugs and medical devices for trace amounts of bacterial toxins that could cause fever or life‑threatening reactions in humans, making the test a regulatory mainstay for product safety.
Conservation concerns and alternatives
Heavy reliance on horseshoe crabs has raised ecological and ethical concerns, prompting research into synthetic or recombinant alternatives that can reduce pressure on wild crab populations while maintaining rigorous safety standards for medicines.
Why it matters
The sensitivity of crab‑derived tests has helped keep vaccines and many medical products safe for decades, and ongoing efforts to find validated alternatives aim to balance patient protection with species and ecosystem conservation.
Quick related facts
- Source: horseshoe crab blood extracts (LAL/TAL).
- Purpose: detects bacterial endotoxins in vaccines and injectables.
- Conservation: demand has prompted development of non‑animal alternatives.
- Public health: test contributes to vaccine and medical safety worldwide.