Companies that sell hand soap for years have touted the ability of their products to kill germs. But the safety of the active ingredient used in many antibacterial soaps and other household items, a chemical called triclosan, is widely being questioned.

As The New York Times reports, studies have found that triclosan may spur resistance to antiobiotics, and that it disrupts the thyroid hormone in frogs and rats and alters the sex hormones of laboratory animals. Those findings have prompted some consumer groups and lawmakers to call for a ban on the chemical in common consumer products.

Triclosan, which was introduced more than 40 years ago as a surgical scrub, is so widely used that it was  found in the urine of 75 percent of Americans over age 5 in a a survey by the Centers for Disease Control and Prevention .

The Food and Drug Administration started writing regulations for antiseptic products such as triclosan more than three decades ago, but the process repeatedly has been delayed. To prod the agency to act, U.S. Rep. Edward J. Markey, D-Mass., has called for a ban on triclosan in hand soaps, as well as in products marketed to children or that come in contact with food.

The FDA, along with the  Environmental Protection Agency, still is studying the safety of triclosan. The FDA was due to announce its findings several months ago, but now says it is unlikely to finish its review until next year. The Natural Resources Defense Council filed a lawsuit last year to push the agency to wrap up its study.

Already, however, the FDA has said that soap with triclosan is no more effective than ordinary soap.

The FDA’s claim is disputed by manufacturers of antiseptic hand soaps, which, according to one market research firm, account for roughly half of the $750 million U.S. market for liquid hand soaps. The products using triclosan include Dial Complete, which has been ranked as the nation’s 5th-leading seller among liquid hand soaps.

Richard Theiler of German-based Henkel, the maker of Dial Complete, disputed research suggesting that triclosan is hazardous and said several new studies proving its germ-killing effectiveness have been submitted to federal regulators. “It has been used now in products safely for decades,” he said.

Other soap manufacturers, however, have stopped using triclosan. For instance, Colgate-Palmolive has removed the chemical from both its Palmolive Antibacterial Dish Liquid and the Softsoap liquid hand soap.

On the other hand, the company continues to use triclosan in its Colgate Total toothpaste. The FDA has approved that use of the chemical, based on the agency’s conclusion that it combats gingivitis.