May 1 marked a pivotal shift in the biomedical industry that changes the tide for imperiled Atlantic horseshoe crabs.

U.S. pharmaceutical companies are now allowed to use animal-free alternatives—the reagents rFC and rCR— in tests to detect toxic substances in injectable medicines and implants rather than the blue blood of the horseshoe crab. The new standard was proposed and adopted by U.S. Pharmacopeia.

“This is what incremental change looks like, and it should be celebrated,” said Priscilla Feral, president of Friends of Animals. “No one should be debating whether their numbers are plentiful enough to allow commercial exploitation or killing of horseshoe crabs in the first place—it’s always been scientifically or morally unjustifiable. Now the biomedical industry has no excuse not to stop wasting the lives of horseshoe crabs.”

In addition to bleeding labs, fishers continue to exploit and kill horseshoe crabs at an alarming rate for bait for eel and whelk, and existing laws are not adequate to protect them. Beyond that, climate change and resulting sea level rises threaten their habitat.

Horseshoe crab egg abundance is important not only as an indication of species population health, but also because horseshoe crab eggs are a vital food source for the red knot, a migratory shorebird currently listed as threatened.

All these factors prompted Friends of Animals to help draft and advocate for legislation that bans the killing of horseshoe crabs for bait in Connecticut. The law passed in 2023, and now FoA is supporting similar legislation that has been introduced in Massachusetts.

FoA has also petitioned the U.S. Secretary of Commerce to list the Atlantic horseshoe crab under the Endangered Species Act.

FoA’s petition points out that as many as 2 million horseshoe crabs were killed annually between 1850 and 1920 for use as fertilizer and livestock feed. Between 1920 and 1960, this destructive practice slowed before ceasing entirely due to population declines. In the 1970s, scientists discovered that the animals’ bright blue blood clots when exposed to harmful bacterial endotoxins, and in the 1980s they began using horseshoe crab blood to develop the Limulus amoebocyte test (LAL) to detect endotoxins in vaccines, medications, needles and biomedical devices.

Bleeding labs, which drain horseshoe crabs of about 30 percent of their blood and turn that blood into LAL, collected 637,029 horseshoe crabs in 2019, 30 percent more than they took the year before. While the crabs are returned to the water, at least 15 percent—or 95,554—die. Some research puts that mortality figure as high as 30 percent.

The lack of standards provided by USP over the years didn’t stop pharma giant Eli Lilly from successfully converting 80 percent of their testing of medicines from horseshoe crab blood to a synthetic alternative.

It’s time for the rest of the industry to follow suit.

Non-animal synthetics are more cost-effective and more widely available than ever, according to a study co-authored by the non-profit Revive & Restore. While there are up-front costs for switching, in terms of new equipment and software, and an investment in time, the synthetics are less expensive so that helps offset costs.