Anti-bacterial chemicals in liquid soaps and washes may not help prevent the spread of germs, and there is some evidence they may pose health risks, experts say.

The US Food and Drug Administration ruling on triclosan and other anti-bacterial ingredients lends new support to long-standing warnings from scientists who say the chemicals can interfere with hormone levels. Under a proposed rule, the agency will require manufacturers to prove that their anti-bacterial cleaners are safe and more effective than plain soap and water.

The agency’s proposal comes more than 40 years after it was first tasked with evaluating triclosan and similar ingredients. Ultimately, the government agreed to publish its findings only after a legal battle with an environmental group, which accused the FDA of delaying action.