Toothpaste biocide forms persistent pollutants

New evidence on triclosan, a bactericide widely used in cosmetics and household goods, suggests that it degrades to form bioaccumulative and environmentally persistent chemicals of unknown toxicity. The data contradict the manufacturer's claims that the chemical poses no threat to the aquatic environment.

Triclosan is a chlorinated phenolic biocide manufactured by Ciba Specialty Chemicals and incorporated in products like toothpaste, deodorants, soaps, clothes and plastic kitchenware. Ciba claims the product is biodegradable, does not accumulate and has "no negative impact on the environment".

However, independent research is increasingly calling these claims into question. The latest study by researchers from the Swiss Federal Research Station shows that a chemical produced by the breakdown of triclosan is bioaccumulating in fish.

Methyl triclosan is formed during the biodegradation of triclosan in sewage treatment works, but is much more persistent and bioaccumulative than its parent compound.1 Marianne Balmer and colleagues have found that fish in Swiss lakes receiving sewage effluent contain up to 360 parts per billion of methyl triclosan in fatty tissue.

"The compound is rather persistent and there is almost nothing published about it," Dr Balmer said. "We do not know about its toxicity." However, the study estimated its bioaccumulation factor at 260,000 - high enough to classify the chemical as "very bioaccumulative" according to the Chemicals Stakeholder Forum's criteria for chemicals of concern.

Previous American research has shown that triclosan can degrade to a dichlorinated dioxin under ultraviolet light. There are concerns that this compound may be bioaccumulative and persistent even though it is not highly toxic.

Despite the evidence, Ciba's website categorically assures customers that "persistent metabolites are not formed" during the breakdown of triclosan. But one environmental chemist who has studied the degradation of the compound has expressed doubts.

Heinz Singer of the Swiss Federal Institute for Environmental Science and Technology has shown that 79% of triclosan in sewage is broken down during treatment. But he told ENDS: "We could not find the main degradation products, nobody has found them so far and I do not believe it goes straight to carbon dioxide and water."

Some 15% of triclosan in sewage ends up in sludge and about 6% remains in the effluent, Dr Singer's work shows. Only a few percent is converted to methyl triclosan, but this becomes environmentally significant because of the compound's persistence and tendency to bioaccumulate.

Ciba says only 350 tonnes of triclosan are used annually in Europe - below the 1,000-tonne threshold which would see it classified as a high production volume chemical and prioritised on national and international lists as a chemical of potential concern. But there is widespread consumer exposure and the compound has been detected in breast milk (ENDS Report 309, pp 12-13 ).

Ciba has dismissed concerns about the bioaccumulation and toxicity of by-products. In a statement to ENDS it maintained that triclosan was a "negligible source of dioxins" and that concentrations of methyl triclosan were insignificant: "The minute concentrations involved and the results of risk evaluations, have not indicated a need for further investigations on persistence and bioaccumulation. Basic toxicity data do not give cause for concern or further examinations."

Nonetheless, the environmental profile of triclosan is in question. Leading UK retailers have been voting with their feet. B&Q has identified it as a priority chemical which it plans to exclude by 2005 (ENDS Report 345, p 35 ). Safeway banned triclosan from new products in 2004 and says it intends to remove it altogether by 2006 (ENDS Report 346, p 33 ). Marks and Spencer is also slowly reformulating products to avoid the chemical.

Reinsurance giant Swiss Re has also warned retailers and manufacturers that triclosan may increase their businesses' product liabilities (ENDS Report 333, p 31 ).

Gwynne Lyons, chemicals policy advisor to WWF UK, observed: "This company [Ciba] appears to care more about making money than reacting to the mounting environmental concerns about this product. First it persuades the public they need a microbial substance in unnecessary places, and then it fails to acknowledge any problem with its environmental persistence."

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