The end of one kind of painful, blinding and lethal laboratory experiment on animals, the Draize test, may be at hand. A new technique to grow human corneal cells, developed by Japanese scientists, allows for more accurate results about the toxicity of chemicals to the human eye than those long-time favorite subjects of cosmetics company researchers, rabbits. And using the lab-grown human cells doesn’t involve any animals.
Thousands of rabbits are tortured every year in Draize tests; dogs and non-human primates are also popular subjects. Researchers lock animals’ necks in pillories (like the stocks for law-breakers in old town squares) that immobilize their heads and block them from reaching their eyes with their paws or arms. Next, researchers put a substance contained in personal care or household products in the animals’ eyes, one eye per subject (so the other eye can be used as a control), and check for changes every hour for up to three weeks. The next step is scoring damage to the animal’s cornea, conjunctiva and iris.
The scientists who developed the new testing material, which consists of human corneal cells grown on an ultrathin collagen sheet, say it is more effective than using the Draize test on live nonhuman animals. Researchers chose 30 substances for which Draize test results are already known and measured their effects on the corneal cells grown in the lab. The number of cells destroyed in the tests matched the Draize scores in 90 percent of trials. For the other 10 percent, the results predicted the substances’ effects on human eyes better than Draize tests on nonhumans did. Chemicals that had been declared non-toxic based on Draize tests were found to be harmful to people’s eyes when the human corneal cells were exposed to them.
This is far from the first clue that Draize tests on animals yielded unreliable results. Nature concluded that animal experiments like the 69-year-old Draize “are stuck in a time warp” and are “often poorly predictive.” The American Anti-Vivisection Society explains that Draize tests yield “highly unreliable safety data” for several reasons.
Obviously, nonhuman animals’ eyes and systems differ from humans’ in significant ways — for instance, rabbits produce fewer tears than humans, meaning that chemicals stay in their eyes longer and irritate them more than they would for humans. Also, the tests expose animals to much higher doses of chemicals, and administer them in different ways, than humans would encounter using products containing the chemicals.
Reuters reports that the lead investigator of the Japanese research team says the collagen sheet they developed can be used to cultivate and experiment on any kind of human cells, such as skin or internal organs. Maybe this discovery will spell the end to quite a few kinds of experiments on animals, like those assessing skin sensitivity.
The European Union has banned cosmetics companies from testing their products on animals, but in Japan and the United States, animals still suffer and die in Draize testing. Because some countries require animal testing, even products sold in the E.U. contain substances that have been tested on animals for sale in other places.
Photo credit: Abdillah Abi