Meanwhile, concerns over other potential health effects continue to grow, fueled in part by the discovery that traces of triclosan and its byproducts are present in human urine, plasma and breast milk.
Federal health research conducted a decade ago concluded that triclosan was in the urine of 75 percent of Americans, with the highest levels occurring in people in their 20s and those with the highest household incomes. The most recent analyses, from 2009-2010, found a slight rise in urinary concentrations and consistent rates of detection.
Research also has indicated that triclosan can disrupt hormones in the body, including a series of studies by EPA scientists over the last six years showing that the chemical can induce hormonal changes in rats.
The concentrations that triggered those changes were much higher than levels reported in humans. But last year, University of California at Davis researchers published a paper in the Proceedings of the National Academy of Sciences that found impaired muscle function in mice whose triclosan blood levels were similar to those seen in some human studies.
"We found it to be quite potent at disrupting the process that leads to cardiac and skeletal muscle contraction and relaxation," said Isaac Pessah, a professor of neurotoxicology. "These findings provide strong evidence that the chemical is of concern to both human and environmental health."
These studies and others recently prompted some health care providers to abandon triclosan, including the entire Kaiser Permanente hospital group.
"Where there is credible evidence for us to think there is a problem with a chemical or product, we consider it our obligation to identify a safer alternative," said Kathy Gerwig, environmental stewardship officer at Kaiser Permanente, which phased out triclosan soaps by 2010.
Some manufacturers also have made changes. Last year, triclosan was among the chemicals Johnson & Johnson said it would remove from its products by 2015. GlaxoSmithKline in 2009 removed triclosan from toothpastes including Aquafresh and Sensodyne. And in 2011, Colgate/Palmolive — which still uses triclosan in its Colgate Total toothpaste — removed triclosan from Ultra Palmolive Antibacterial Dish Liquid, replacing it with lactic acid.
"There has undeniably been a backlash about triclosan in household soaps, but it seems limited to a certain segment of the population (typically, the better informed consumer)," wrote industry analyst Mike Richardson of the Freedonia Group, a business research firm. "I don't know that they're right about triclosan, but they at least know that other people are worried about it."
As the EPA begins its review, expected to take six years, worry is increasing among environmental groups and scientists about triclosan residues in sewage sludge, waterways, aquatic animals and earthworms.
Last month, University of Minnesota scientists reported in Environmental Science and Technology that levels of triclosan and its byproducts are rising in Minnesota lakes where wastewater is dumped, a trend the scientists link directly to use of the chemical in consumer products.
The American Cleaning Institute took issue with the study, saying researchers found "vanishingly low levels of the chemical in the environment" and there "are no negative impacts associated with those trace compounds."
The study's lead author calls that argument "disingenuous."
"Even when things are in small concentrations in the environment, you have biological processes that can concentrate them in organisms," said William Arnold, a professor of civil engineering at the University of Minnesota.
Last spring a Canadian government report concluded that triclosan "in significant amounts" can harm the environment, a development that U.S. Rep. Edward J. Markey, D-Mass., said "underscores the urgency for the FDA to release its nearly four-decades-overdue final rule on this dangerous chemical. … It poses a public health concern and continues to pollute our bodies."
Markey has urged the government to ban triclosan from materials that come into contact with food products and those intended for children's use.
The chemical's leading U.S. manufacturer, BASF-owned Ciba, stresses that it is "dedicated to the responsible management of the health, safety and environmental aspects of triclosan and all of our products throughout their life cycles."
The company did not answer follow-up questions about studies on hormone disruption and other potential harm except to say that "we do not have the full details or methods and do not know if our products were involved."
Janssen of the resources defense council, which is suing the FDA over its delays on triclosan, said the anti-microbial chemical is not the only ingredient of concern that the agency has allowed on the market for decades before determining its safety and issuing rules for use.
Citing bisphenol A and compounds in sunscreen as other examples, Janssen said the long delays "benefit the industry FDA is supposed to be regulating rather than the consumers it is mandated to protect."
The "billion-dollar anti-bacterial soap industry has a lot to gain from FDA's delays," said defense council attorney Mae Wu, while "the public has "been turned into their guinea pigs."
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