WASHINGTON — It is a chemical that has been in US households for more than 40 years, used in things like body wash and the baby’s basinet.
But federal regulators are just now deciding whether triclosan — the germ-killing ingredient found in an estimated 75 percent of antibacterial liquid soaps and body washes sold in the United States — is ineffective, or worse, harmful.
The Food and Drug Administration plans to deliver a review this year of whether triclosan is safe. The ruling, which will determine whether triclosan continues to be used in household cleaners, could have implications for a $1 billion industry.
The review comes amid growing pressure from lawmakers, consumer advocates, and others who are concerned about triclosan. Recent studies in animals have led scientists to worry it could increase the risk of infertility, early puberty, and other hormone-related problems in humans.
‘‘To me it looks like the risks outweigh any benefit associated with these products right now,’’ said Allison Aiello, a professor at the University of Michigan’s School of Public Health.
The concerns over triclosan offer a sobering glimpse at a little-known fact: Many chemicals in household products have never been formally approved by US health regulators. That’s because many germ-killing chemicals were developed decades ago, before there were laws requiring scientific review of cleaning ingredients.
The controversy also highlights how long it can take the federal government to review the safety of such chemicals. It’s not uncommon for the process to take years.
As for triclosan, Congress in 1972 required the FDA to set guidelines for dozens of common antibacterial chemicals. They function like a cookbook for manufacturers, detailing which chemicals can be used in what products and in what amounts.
In 1978, the FDA published its first tentative guidelines for chemicals used in liquid hand soaps and washes. The draft stated that triclosan was ‘‘not generally recognized as safe and effective,’’ because regulators could not find enough scientific research.
The FDA published several drafts of the guidelines over the years, but the agency never finalized the results.
The agency did approve triclosan for use in Colgate’s Total toothpaste in 1997, after Colgate-Palmolive Co. submitted data showing the ingredient helped fight gingivitis.
Last summer, the FDA said its triclosan review would be done in late 2012. The target date then slipped to February.
In March, a federal appeals court said a lawsuit by the Natural Resources Defense Council aimed at forcing the FDA to complete its review could move forward. A three-judge panel reinstated the 2010 lawsuit, saying the nonprofit group presented evidence that triclosan could be dangerous.