Personally, I wouldn't mind if the stuff was banned tomorrow. I once used tea tree oil in a shampoo. Never again. I liked the smell of menthol and the cooling sensation - the top of my skull felt as though it had lifted half an inch off my head. But after every up there is always a down. Within hours my scalp started to itch, and then to flake. The next day, it looked like a Colombian drug baron had sneezed across my shoulders. I dived into the shower for relief.
Tea tree oil is powerful stuff. It is also ubiquitous. Its popularity has seen it included as an ingredient of lotions and creams for acne, as an antiseptic for cuts and grazes and as a mild astringent in shampoos, shower gels and vapour rubs.
Its versatility has attracted the interest of scientists - and they have sounded a note of caution. The International Fragrance Association warned in 2001 that the product could be irritating to the skin; this warning was mainly to protect factory workers producing and handling the stuff in large quantities.
The European Cosmetics Association recommended in 2002 that tea tree oil should be limited to a concentration of 1 per cent in cosmetic products. This opinion was backed by Germany's Federal Institute of Risk Assessment in 2003.
In December 2004, the European Commission's scientific committee on consumer products published the most thorough analysis yet of the safety of tea tree oil. It concluded that its use in cosmetics and soaps, where its concentration did not exceed 1 per cent, was unlikely to be harmful. At higher than 1 per cent, there was a risk it might cause skin irritation in some people.
But tea tree oil is also sold neat - as an antiseptic; as a treatment for spots and pimples; and as an insect and lice repellant. The scientific committee said it could not judge whether products containing high concentrations of tea tree oil, of up to 100 per cent, were safe and requested more information from the manufacturers. Its blunt conclusion was: "The sparse data available suggest [that] undiluted oil as a commercial product is not safe."
Most tea tree oil is produced in Australia; it is derived from the Australian metaleuca tree and has been used as a traditional remedy by Australian Aborigines for centuries. It was used by Australian soldiers during the First World War as an antiseptic for wounds, and more recently it has been cited as a potential weapon against the superbug MRSA.
The Australian Tea Tree Oil Industry Association is due to submit a dossier of evidence on the safety of the neat product by the end of next month, having missed the initial deadline of the end of 2005. The EU scientific committee will then consider its verdict.
Customers, retailers and manufacturers now await the outcome with varying degrees of anxiety. Chris Flower, the director general of the Cosmetic Toiletry and Perfumery Association, is relaxed. He says: "People using tea tree oil products should carry on without worrying. There is no issue in relation to its safety in cosmetics. The only real concern is over its use neat. The problems in that case can be avoided by not overdoing it. It is a matter of common sense."
Flower added: "I expect the EU committee to say [that the neat product] is fine. They may have specific recommendations about the number of times it is used. Or they may say they are not convinced and they may demand more data."
A spokeswoman for the European Commission said that tea tree oil contained "several hundred constituents" and it would take time to assess their safety. It might be possible to adjust the constituents if any were found to be unsafe, she said: "We cannot prejudge the scientific opinion."
Two factors have muddied the waters. Earlier this month, a review in The New England Journal of Medicine warned parents to avoid using tea tree oil products on their children after three reports of boys growing breasts.
Researchers in the US believe that the oils, which included lavender oil, may have hormone-like properties that lead to gynaecomastia - the growth of breasts. When the boys stopped using the oils, their breasts disappeared. One of the boys, aged 10, had regularly used a styling gel containing lavender and tea tree oil on his hair and scalp.
The researchers from the National Institutes of Health and the University of Colorado School of Medicine said that the oils "may possess endocrine-disrupting activity that causes an imbalance in oestrogen and androgen pathway signalling". Laboratory tests showed that the oils mimicked the activity of the female hormone oestrogen.
Flower dismissed the research. "The findings seem very unlikely to me. We are talking about a very small number of cases who were not thoroughly investigated to see what other things they might have been exposed to. I am not aware of people working in tea tree oil factories suffering ill effects , or of people in the South of France where most lavender is grown and processed."
A second factor worrying scientists is the stability of the product. Tea tree oil tends to oxidise when exposed to light and air, and this can increase its irritant effect. The EU scientific committee said the stability of the oil in cosmetics was questionable and tests should be developed to monitor its degradation. "Our major concern is that toxic and risky chemicals become even more potent - up to three times as strong - if stored at room temperature and exposed to light and air," the committee said.
Some campaigners think this is alarmist. Oxidation can be minimised by adding antioxidants such as vitamins C and E, or altering the formulation of the product.
Tony Burfield of Cropwatch, a lobbying group for traditional remedies, warns of the danger of pandering to the interests of big pharmaceutical business. He says a full scientific critique is in preparation that will meet the EU scientific committee's concerns. But until the boffins of Brussels are satisfied, the centuries-old remedy's place on pharmacy shelves is under threat.Reuse content