Animal testing

If you have ever gotten a vaccine or received an intravenous drug and did not come down with a potentially life-threatening fever, you can thank a horseshoe crab (Limulus polyphemus). How can animals that are often called living fossils, because they have barely changed over millions of years, be so important in modern medicine? Horseshoe crab blood is used to produce a substance called limulus amebocyte lysate, or LAL, which scientists use to test for toxic substances called endotoxins in intravenous drugs. These toxins, produced by bacteria, are ubiquitous in the environment and can’t be removed simply through sterilization. They can cause a reaction historically referred to as “injection fever.” A strong concentration can lead to shock and even death. Identifying LAL as a highly sensitive detector of endotoxins was a 20th-century medical safety breakthrough. Now, however, critics are raising questions about environmental impacts and the process for review...