Animal-Based Drug Tests Miss Half of All Birth Defects

“We may be betting the health of our children on odds only a little better than a coin flip,” says Jarrod Bailey, Ph.D., a senior post-doctoral research associate at the University of Newcastle Upon Tyne School of Surgical and Reproductive Sciences in England.

Bailey recently completed a comprehensive review of the scientific literature examining birth defects and found that animal experiments are such poor predictors of human birth defects, the tests are accurate only slightly more than half the time. A part-time PCRM consultant, Bailey looked at studies of nearly 1,400 different substances, including many common drugs and household chemicals.

Potential teratogens—drugs and chemicals that can cause birth defects—are tested using mice, rats, rabbits, dogs, hamsters, monkeys, and other animals. Bailey maintains that none of these animals can adequately predict defects in humans.

The problem stems from fundamental biology. There are simply too many differences in physiology and biochemistry between humans and other animals, he explains. No nonhuman animal species absorbs, metabolizes, or eliminates test substances like a human.

As a result, researchers often test drugs and other compounds across a wide spectrum of species, a practice that often leads to conflicting and contradictory results. Thalidomide, a sedative and anti-nausea medication given to pregnant women in the 1960s, for example, resulted in thousands of tragic birth defects. Most animal tests showed thalidomide to be safe.

Fortunately, better test methods now exist, and PCRM is actively promoting them. One, the Embryonic Stem Cell Test, has been proven to be more accurate, cheaper, quicker, and easier to use than animal experiments.

Dr. Bailey’s full review is scheduled for publication this May in the European scientific journal Biogenic Amines.

PCRM Online, March 2005

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