The Food and Drug Administration says there is no evidence that antibacterial chemicals used in liquid soaps and washes help prevent the spread of germs, and there is some evidence they may pose health risks.

The agency said it is revisiting the safety of chemicals like triclosan in light of recent studies suggesting they can interfere with hormone levels and spur the growth of drug-resistant bacteria.

The government’s preliminary ruling lends new credence to longstanding warnings from researchers who say the chemicals are, at best, ineffective and at worst, a threat to public health.

Under its proposed rule released Monday, the agency will require manufacturers to prove that their antibacterial soaps and body washes are safe and more effective than plain soap and water. If companies cannot demonstrate the safety and effectiveness of their products, they would have to be reformulated, relabeled or possibly removed from the market. The agency will take comments on its proposal before finalizing it in coming months.

“Due to consumers’ extensive exposure to the ingredients in antibacterial soaps, we believe there should be a clearly demonstrated benefit from using antibacterial soap to balance any potential risk,” said Dr. Janet Woodcock, director of the FDA’s drug center.

The agency’s proposal comes more than 40 years after the agency was first tasked with evaluating triclosan and similar ingredients. Ultimately, the government agreed to publish its findings only after a three-year legal battle with the environmental group, Natural Resources Defense Council, which accused the FDA of delaying action on triclosan. The chemical is found in an estimated 75 percent of antibacterial liquid soaps and body washes sold in the U.S.

The FDA’s preliminary rule only applies to personal hygiene products, but it has implications for a $1 billion industry that includes thousands of antibacterial products, including kitchen knives, toys, pacifiers and toothpaste.

Most of the research surrounding triclosan’s safety involves animal studies, which cannot always be applied to humans. But some scientists worry the chemical can disrupt hormones in humans too, raising the risk of infertility, early puberty and other developmental problems. Other experts are concerned that routine use of antibacterial chemicals like triclosan is contributing to a surge in drug-resistant germs, or superbugs, that render antibiotics ineffective.

In March 2010, the European Union banned the chemical from all products that come into contact with food, such as containers and silverware.

(AP)