An association of pharmacologists yesterday said that the Food and Drug Administration's testing of the recently approved contraceptive sponge was "grossly inadequate" and that the product should be withheld from the market until further study.
"The FDA didn't follow its own rules in approving the product," said Dr. Armand Lione, president of the non-profit Associated Pharmacologists and Toxicologists, a small Washington-based research group. Also petitioning the FDA to reassess its approval of the product was the New York-based Empire State Consumer Association Inc.
Lione said the agency's safety testing did not include adequate animal studies and that the spermicide the sponge would carry contained trace amounts of dioxane, which has been shown to cause cancer in laboratory animals.
Since 1979, FDA guidelines have called for extensive animal testing of new vaginal contraceptives. But an FDA spokesman said that in this case, the agency did not perform some of the animal tests because the sponge, made of polyurethane, was considered biologically inert and because the spermicide to be used had "a 20-year history of safety" in other birth control products.
Lione cited studies suggesting that polyurethane can break down and be absorbed in the body and expressed concern about possible exposure to dioxane, which is present in very small quantities in almost all spermicidal preparations.
"It's a question of risk assessment," said Dr. Soloman Sobel of the FDA's New Drug Approval Division. "Studies have found liver tumors with polyurethane byproducts, but at exposure levels almost 12 million times higher than could be expected from the sponge."
Sobel said the possibility of cancer from dioxane residue in spermicide was "insignificant," but that the threat of chromosomal damage to fertilized eggs from exposure to the chemical in the womb was being reassessed by the FDA.
"We're moving toward requiring all manufacturers to warn women not to use spermicides if they suspect they are pregnant," he said. Although earlier studies suggested a connection, new research by the federal Centers for Disease Control in Atlanta found no association between birth defects and spermicide use.