U.S. scientists agree that the FDA's review is overdue. The Endocrine Society, a group of doctors and scientists who specialize in the hormone system, flagged triclosan four years ago as an ingredient that alters levels of thyroid hormones and reproductive hormones like testosterone and estrogen.
"I think the FDA is behind the curb," said Dr. Andrea Gore of the University of Texas at Austin, who was the lead author of the Endocrine Society's statement on hormone disrupting chemicals. "At what point do you draw a line and say we need to take this out of products that are being applied to our skin? What is enough evidence?"
Some Americans are shocked that the FDA has taken so long. Mallory Smith is troubled to learn that the government has never confirmed the safety of antibacterial soap's key ingredient.
Smith, who works for the federal government, says she keeps antibacterial soap in the kitchen to clean her hands after she's handled raw meat.
"As a regular consumer I rely on the government to identify products that are safe for me to use," Smith said. "If something is brought to their attention, they should look into it, and ban the chemical if necessary."
Others are less surprised by the government's multi-decade review. "It sounds like a typical government agency to me: totally unproductive," said David Fisher, who sells restaurant equipment in Arizona.
Ironically, triclosan first became widely used because it was considered safer than an older antibacterial ingredient, hexachlorophene. That chemical was banned from household items in 1972 after FDA scientists discovered that toxic levels could be absorbed through the skin. Several infant deaths in France were connected to baby powder that contained unsafe levels of the chemical, because of a manufacturing error.
Triclosan was initially used in hospitals in the 1970s as a scrub for surgeons preparing to perform an operation. It was also used to coat the surfaces of catheters, stitches and other surgical instruments.
Beginning in the 1990s, triclosan began making its way into hundreds of antibacterial consumer goods, ranging from soap to socks to lunchboxes. The growth has in part been fueled by Americans who believe that antibacterial ingredients provide an added level of protection against germs.
As the use of triclosan has expanded, more scientists have questioned its effectiveness. In 2007, researchers at the University of Michigan and other universities compiled data from 30 studies looking at the use of antibacterial soaps. The results showed soaps with triclosan were no more effective at preventing illness or reducing bacteria on the hands than plain soap.
Other studies have shown that longer hand-washing improves results far more than adding antibacterial ingredients. The Centers for Disease Control recommends washing hands at least 20 seconds. The CDC also recommends using hand sanitizer -- most of which use alcohol or ethanol to kill germs, not chemicals like triclosan -- if soap and water are not available.
Troclosan's safety also has become a growing concern in recent years. To date, nearly all of the research on triclosan's health impact comes from animal studies -- which are not necessarily applicable to humans -- but the findings still have researchers concerned.
A 2009 study by scientists at the Environmental Protection Agency showed that triclosan decreases levels of testosterone and sperm production in male rats. Female rats exposed to triclosan showed signs of early puberty and altered levels of estrogen and thyroid hormones.
And a 2010 study by University of Florida researchers found that triclosan interfered with the transfer of estrogen to growing fetuses in pregnant sheep. Estrogen is important in both male and female development because it promotes growth of organs like the lungs and liver.
Sansoni, the soap and detergent industry spokesman, says those animal studies can't be applied to humans and "make exaggerated claims about the damaging effects" of triclosan.
But safety concerns over triclosan don't just involve rats and other animals. Some experts argue that routine use of antibacterial chemicals like triclosan is contributing to a surge in drug-resistant germs, or superbugs, that are immune to antibiotics. Few studies have attempted to track antibiotic resistance tied to Triclosan in the real world. But laboratory studies have shown that antibiotic-resistant strains of E. coli and other bacteria can grow in cultures with high levels of triclosan.
As a result of the growing concerns, some leading medical societies, hospitals and companies have abandoned the chemical.
Kaiser Permanente pulled triclosan from its 37 hospitals across the country in 2010, switching to traditional soaps and alcohol-based hand sanitizers. Kathy Gerwig, Kaiser Permanente's vice president for workplace safety, said the hospital chain decided to phase out triclosan as part of its "precautionary approach" to safety issues.
"If there is credible evidence that a product we're using might have some disadvantages from a health or environmental standpoint, then it's our obligation to look for a safer alternative," Gerwig said.
Johnson & Johnson has pledged to remove triclosan from all of its adult products by the end of 2015. The company says none of its baby products currently contain the ingredient."We want people to have complete peace of mind when they use our products," Susan Nettesheim, vice president of product stewardship, said when the company made the announcement last summer.