Chinese authorities are investigating the circumstances behind an international cancer scare over antibacterial soap and toothpaste.

Research conducted by Peter Vikesland, an environmental chemist at Virginia Polytechnic Institute and State University in the US, showed that chlorine in tap water and the antibacterial chemical triclosan in some soaps and other products can react to create the probable carcinogen chloroform.

In response, British retailer Marks & Spencer decided to remove triclosan-enhanced toothpastes from store shelves.

However, The Roanoke Times reported earlier this week that Vikesland said on Monday that this was an apparent overreaction to his report, and that he did not intend for anyone to conclude that triclosan is unsafe or poses an immediate health concern.

Although no products were withdrawn from sale in Beijing, the findings made headlines in the Chinese media, raising consumer concern over Colgate toothpaste and other triclosan-enhanced products.

The General Administration of Quality Supervision, Inspection and Quarantine said on Tuesday that it and the Standardization Administration of China have begun looking into case.

"To make an accurate and reasonable judgment, a standard needs to be developed on the basis of research, experimentation and data. That process will take some time," the agency said in a statement.

Colgate-Palmolive (Guangzhou) Co., with at least one of its toothpaste products containing triclosan, said that competent authorities worldwide have certified its products as safe and effective.

China's national toothpaste standard, GB8372, does not regulate the amount of the triclosan that toothpaste may contain. Current testing on these products focuses on the presence of microbes and heavy metals, according to industry sources.

A spokesman for the Beijing Consumers' Association said on Tuesday that it had not received any complaints about Colgate toothpaste.

Professor Wu Weikai of the China Center for Disease Control and Prevention said on Tuesday that he believed the risk posed by use of the toothpaste is almost "negligible," as triclosan in toothpaste is present in very small amounts, and the chloroform produced when it is mixed with chlorinated water is also minimal.

The US Environmental Protection Agency website indicates, "chloroform has been shown to be carcinogenic in animals after oral exposure, resulting in an increase in kidney and liver tumors." The agency classifies the chemical as probable human carcinogen, but points out that this assessment is based on high-exposure conditions that lead to cell death and regrowth in susceptible tissues. Some US states regard chloroform as a "known carcinogen."

Vikesland was quoted in The Roanoke Times as saying that he thinks a writer or writers picked up his research after it was published on April 2 and posted their fears on the Internet. As the versions were picked up and posted on other sites, the facts became garbled and the fears escalated. He said that he had seen websites in France and China carrying nonscientific versions of the story.

The original research, which appeared in the Environmental and Science Technology journal, warned "the potential exists for substantial chloroform production to occur via daily household use of triclosan-containing products." Vikesland and other researchers agree that extensive additional studies must be conducted before making any conclusions about possible hazards of normal household use.

(China Daily, China.org.cn April 20, 2005)