A Food and Drug Administration ban on over-the-counter antiseptic soaps and cosmetics containing certain active ingredients goes into effect Sept. 6.

But it's up to consumers to avoid products the ban doesn't cover.

The FDA issued its final ruling last year on 19 ingredients found in thousands of consumer antibacterial products.

The chemicals, which include triclosan and triclocarban, have been widely used for decades. They pose possible health risks, cause environmental harm and could worsen antibacterial resistance. Yet there is little proof exists that they are more effective than plain soap and water.

"There had been efforts to prove their safety for many decades, really. And the evidence accumulated over time that the chemicals actually might have significant health risks, and yet didn't quite deliver on the front of killing the germs as advertised," said Rolf Halden, director of the Center for Environmental Health Engineering at Arizona State University.

Halden led "The Florence Statement on Triclosan and Triclocarban," a consensus paper representing more than 200 scientists and 29 countries.

The paper summarized the case against triclosan and triclocarban, and called for better product labeling.

"It's really easy, you know? If you have a chemical that poses potential risks but offers no benefit, it's a chemical you don't want — in your products and in your body," Halden said.

The ban affects only FDA-regulated products like soaps and cosmetics, so the chemicals can remain, unlabeled, in building materials, clothing, toys and other products. Halden said there are two issues with such products.

"One is, they can essentially claim a fact without having the data that supports that they actually are superior to other conventional products," Halden said. "And the second thing is that, for the consumer, it's very difficult to find out what actually is in the products that they see in the supermarkets."

The prohibition also excludes antibacterial soaps used in hospitals and food services.

Moreover, the FDA will allow Colgate-Palmolive to continue using triclosan in its Colgate Total toothpaste, because studies have shown that it is more effective than fluoride alone.

"There's many, many products that still contain them. My recommendation to the consumer would be to avoid products that claim that they are antimicrobial or antibacterial," said Halden.

Originally used by the chemical industry, and by surgeons to sterilize their hands, triclosan exploded in popularity in the late 1990s, riding a wave of consumer obsession with antibacterial and antimicrobial products.

The FDA considered removing triclosan from certain consumer products as early as 1978. The agency had banned DDT in 1972 and would go on to ban polychlorinated biphenyls (PCBs) in 1979.

Halden said both substances are chemically similar to triclosan and triclocarban.

But the FDA took no action for 30 years, even as evidence for harm — and against efficacy — mounted.

Then, in 2010, the Natural Resources Defense Council sued the agency in the U.S. District Court for the Southern District of New York to force the FDA to issue a final rule. The case was settled by consent decree in 2013, and the agency committed to taking final action on consumer uses of the ingredient by 2016, when it unissued the ban.

Triclosan survives water purification, can cross the placental barrier and has been widely detected in urine and breast milk. Scientists worry that it contributes to antibacterial resistance, and studies show that it can cause endocrine-disrupting effects in animals, such as sexual maturation problems, premature births and miscarriages.

"Essentially, they rearrange the traffic signs in the human body, and that can have sometimes devastating effects. Now, these effects are not necessarily measurable in an individual but, for public health experts, they can observe changes on the population level," said Halden.

Many unanswered questions remain. What constitutes a harmful level of such chemicals, especially those that accumulate in fats? How much will the ban reduce levels of these substances in animals and in the environment, given that other products in the U.S. and abroad continue using them? Will the ingredients that replace the banned chemicals prove better or worse?

Only time — and more studies — will tell.

For now, Haldon said that consumers should take the opportunity to reflect on the dangers of needless exposure to powerful chemicals designed to kill pests or bacteria.

"The regulations of triclosan and triclocarban just reinforce the message that we should just use these types of chemicals if we need them," Halden said. "And they ideally should be prescribed by professionals, like a physician or a pest control expert."