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SHAPING THE FUTURE
FOR THE TEA TREE INDUSTRY
A research update on the tea tree industry from RIRDC distributed to researchers, industry, government, farmers, libraries and consultants. Contributions are welcome. Contact Roslyn Prinsley, RIRDC General Manager Research on Phone 02 6272 4033, Email: roslynp@rirdc.gov.au
In this issue:
Dr Jane Greig and her colleagues tested over 200 healthy adult volunteers for allergy to tea tree oil. Two tests were performed using ten different samples of 100% tea tree oil. Various common allergens were also tested to determine the relative reactivity of the study population.
Low risk of immediate allergy
In the first test, nearly 50% of volunteers exhibited immediate allergy to grasses and dust-mite, indicating that the group was more reactive than the general population (where about 25% of people react to these allergens). Only 4 people (1.8%) reacted to tea tree oil, and each to only 1 or 2 of the 10 oils tested, indicating that the responses were probably not to tea tree oil itself (although the team was unable to determine whether there was another factor responsible). Thehigh reactivity to common allergens adds even greater emphasis to the very low risk associated with immediate allergy to tea tree oil.
… and contact allergy
The other test was for a delayed reaction, which is often called contact allergy. The study population was again somewhat more reactive than expected, with 20% having an allergy to the metal nickel when this would not normally exceed around 15%. The prevalence of allergy to tea tree oil in the entire study group was 2.9%, increasing to a possible 4.8% if reactions that were indistinguishable from irritant responses were included. Allergic and irritant responses occur by different mechanisms and often have distinguishing characteristics, but these differences are not always clear.
Allergy requires previous exposure to the substance in question. Of the subjects who had used tea tree oilbefore (63%), the prevalence of allergy was 4.6% up to a possible 7.6%. This represents a probable maximum level of allergy, if the entire population were to come into contact with tea tree oil.
Irritant reactions
Marked irritant reactions occurred in 2.4–4.3% of subjects, with up to 10.1% experiencing some form of irritancy. Irritant reactions reflect damage to the surface of the skin, and can be controlled by decreasing the exposure time and, more importantly, the concentration of the substance. The use of tea tree oil products, rather than 100% oil, would greatly reduce the risk of irritant reactions.
You can buy a copy of the final report of this project from RIRDC on phone 02 6272 4819, fax: 02 6272 5877. It costs $10 plus postage - $4 within Australia, $8 overseas.
Irritant contact dermatitis is concentration-dependent. This means that the lower the concentration of the substance, the less likely it is that a reaction will occur. Allergic contact dermatitis is far less concentration dependent, but may still be somewhat affected. The possibility that there may be a "threshold concentration" for allergy as well as irritancy became apparent during skin sensitivity testing for tea tree oil, when one person who was allergic reported regular uneventful use of a product containing tea tree oil. Our aim is to determine whether there is a concentration below which allergic reactions do not occur, and whether this varies on an individual basis or is the same for many people who are allergic to tea tree oil. As tea tree oil is active against microbes at very low concentrations, it is possible that it may be useable at concentrations that are both beneficial and almost universally safe.
Tea tree oil is found in many products, and it has become apparent during testing for antimicrobial activity that some of the other substances in a product can compromise the ability of tea tree oil to kill microbes. It is possible that other substances in tea tree oil products will also affect its capacity to cause allergies. We are testing the effect of some common product components on tea tree oil allergenicity.
The exposure of tea tree oil to light and air results in oxidation of the oil. Not only does this decrease the relative concentrations of the significantly antimicrobial components, but it may also increase the irritating capacity of the oil. After storing oil in a variety of conditions for a number of months, we will determine the composition of these samples and then test whether there is any difference in reactivity to the oils.
It is clear that 100% tea tree oil has the capacity to cause marked irritation to some skin. We plan to take small punch biopsies of skin after extended (48 hours) exposure to tea tree oil, and examine the effects on skin at a microscopic level.
Contact: Dr Jane Greig or Professor Tom Riley, Queen Elizabeth II Medical Centre, Nedlands WA 6009; Ph (08) 9346 1986; Email jgreig@cyllene.uwa.edu.au or Ph (08) 9346 3690; Email triley@cyllene .uwa.edu.au; Fax (08) 9346 2912.
RIRDC Project UWA-50 is to be conducted at the University of Western Australia, primarily by Ms Kate Hammer. It arises from other investigations by the UWA research group into the in vitro susceptibility of yeasts to tea tree oil. The yeasts previously investigated include Candida, the organisms causing oral and vaginal thrush, and Malassezia, which is involved in seborrhoeic dermatitis and dandruff. These studies showed that Candida albicans, Candida glabrata and Candida parapsilosis were inhibited and killed by 0.12–0.5% tea tree oil and that Malassezia were inhibited and killed by concentrations of 0.12–1.0% tea tree oil. Now that it has been demonstrated that tea tree Christine oil is active against some yeasts, this project will investigate other yeast species and examine the ways in which tea tree oil affects their morphology and development.
The project will also investigate the susceptibility of dermatophytes to tea tree oil. These comprise the filamentous fungi Epidermophyton, Microsporum and Trichophyton, which cause fungal infections of the skin such as tinea, athlete’s foot, ringworm and nail infections. At present, limited data are available describing the activity of tea tree against these organisms; a thorough, systematic investigation is now urgently needed to provide evidence of the potential usefulness of tea tree oil and tea tree oil products for the treatment of fungal skin infections.
Contact: Kate Hammer or Professor Tom Riley, Queen Elizabeth II Medical Centre, Nedlands WA 6009; Ph (08) 9346 1986; Email khammer@cyllene.uwa.edu.au or Ph (08) 9346 3690; Email triley@ cyllene.uwa.edu.au; Fax (08) 9346 2912.
To address this, in 1998 Dr Prue Hart and Professor John Finlay-Jones at Flinders University in Adelaide and Ms Christine Carson and Associate Professor Tom Riley at the University of Western Australia in Perth commenced a project (UWA-43A) funded by the RIRDC Tea Tree R&D Program to examine the anti-inflammatory activity of tea tree oil.
Inflammation is a dynamic, multi-step process that begins when the body is challenged by something that the immune system identifies as foreign. Many things can provoke an inflammatory response including bacteria, insect bites or common allergens such as pollen, nickel or perfumes. The body responds to such challenges by releasing a range of chemicals known as mediators. These mediators include compounds such as tumour necrosis factor alpha (TNF_), interleukin-1 (IL-1), interleukin-10 (IL-10) and prostaglandins (PG). These mediators orchestrate the activities of the cells of the immune system that comprise an inflammatory response.
When human white blood cells are cultured in the laboratory, they can be provoked into releasing the mediators that produce an inflammatory response: that is, they can be stimulated to release mediators such as TNF_, IL-1, IL-10 and PG. However, when tea tree oil is added to stimulated cell cultures, the cells release lower levels of some mediators. This may be likened to diminished inflammation. Whether this happens in the body is being pursued in the present study; results should be available later this year.
Contact: Christine Carson or Professor Tom Riley, Queen Elizabeth II Medical Centre, Nedlands WA 6009; Ph (08) 9346 3288; Email ccarson@cyllene.uwa.edu.au or Ph (08) 9346 3690; Email triley@ cyllene.uwa.edu.au; Fax (08) 9346 2912.
• Ms Patricia Bolster, Australian Tea Tree Industry Association;
• Mr Robert Tillman, Australian Plantation Pty Ltd;
• Mr Fabio Petrusa, North Queensland Essential Oils Cooperative;
• Dr Richard Spurway, NSW Agriculture;
• Mr Steen Jorsal, Australian Bodycare;
• Mr Don Glover; Oceana Agriculture; and
• Dr Roslyn Prinsley, Rural Industries R&D Corporation (in her capacity as Research Manager for the Tea Tree R&D Program).
RIRDC would like to record its appreciation for the excellent work of the previous committee, and extends a sincere thank you to outgoing members Richard Davis, Christopher Dean and Dick Groot-Obbink. USFDA
What has the Advisory Committee achieved over the period of your chairmanship?
It has put in place a better system for receiving submissions for R&D work. It has adopted a format whereby not only an industry panel but also experts can be co-opted to review submissions. This was particularly true with regards the breeding program, where all the submissions were sent out to an independent panel to ensure we funded the best of them. It has also managed the reports that have arisen from the research and ensured their publication.
What role do you see for it in the future?
I would see a pretty similar role. I’d like to see the committee become more active in commissioning research. The committee consists of members of industry, who reflect the interests of the industry with regards to the research that should be funded, and researchers. Where required, the committee seeks independent advice on the value of submissions. I would like to see an industry body such as the Australian Tea Tree Industry Association take on more of a promotional role with regards the reports produced by the Advisory Committee so that the findings can be best adopted.
What are the prospects for the industry in Australia?
The potential for further growth is very large. At the moment there’s an over-supply, not because the market’s folded but because growth in production has been exponential. However, given time and further R&D there are a lot of things for which tea tree has excellent application. So I see a pretty solid future in the longer term, but perhaps some difficult times in the meantime.
What has the Advisory Committee achieved over the period of your involvement?
It has achieved several things. First of all it has stopped a lot of unnecessary duplication and waste of funds. It has conserved a very small research pool and given it some direction. Its early achievements were in agricultural work, which certainly led to gradual improvement in agronomic practices.
It has also had an impact, albeit at a slower pace, in efficacy and safety. Early attempts at efficacy studies led us up a few blind paths. Eventually, we took a decision to offer a stream of work to a single group of expert researchers so that they would build on their expertise, they would learn from their mistakes and become better at it. And this definitely happened and we now have a pool of highly experienced researchers in that field. And I think this is a very valuable outcome of our endeavours.
What role do you see for it in the future?
One of the big related achievements through the industry was getting a voluntary levy in place, which has started to guarantee some real funds to do some serious research. I believe that in the next decade, the research pool of funds is going to grow dramatically. With more funds and a sophisticated research base to draw on, I think we will start to see what I call tertiary gains. It’s like a three-stage rocket: the first two stages don’t seem to get you anywhere, they work very hard and go slowly, but the third one suddenly takes off and pushes you out at flight speed. And I think that’s really what’s happening in research now; we’re starting to narrow it down to some very substantial improvements for the industry.
What are the prospects for the industry in Australia?
Prospects for tea tree oil in Australia are good. But everything needs
renewal. We’re now facing the challenge of making tea tree a safer product,
a more friendly consumer product, a more effective product, through better
presentation and different product forms. So the future is in more sophisticated
packaging and presentation as well as in formulation work to get us very
much more specific product activity. So research needs have never been
greater. We’re facing a glut of tea tree oil, we’re facing substantial
oversupply in a market that is actually becoming complacent, if not bored,
and looking for the next new thing. And if tea tree can’t start producing
some new and exciting results, it’s going to start to lose market share
to other exciting and innovative phytopharmaceuticals. The industry also
desperately needs substantial research on industrial applications for tea
tree oil. And I believe there are applications such as using tea tree in
the control of bacteria in things like machine oil and industrial oil,
which would have vast implications for the consumption and value of tea
tree oil.
Tea tree oil should only be used topically due to its systemic toxicity; this limits its applications mainly to skin and mucosal conditions. Nevertheless, demonstrating antiviral activity would have significant implications for the industry. While there are only a few skin infections like cold sores that involve viruses, they are very common and few alternative treatments are available. In addition, despite the limited range of treatment applications, the antiviral activity of tea tree oil may be useful for more general purposes, such as hand-washing, where the aim is to kill or remove potential disease-causing organisms.
Viruses do not grow freely in pure culture in the laboratory – they must be grown in host cells, which themselves are grown in thin layers on plastic flasks and then infected with virus. Under these conditions, the virus replicates and creates areas of damage in the layer of host cells. These areas of damage, or plaques, can be seen easily using a light microscope. If an antiviral agent is added to the mixture, the viruses cannot replicate and no areas of damage are seen. When tea tree oil is added to virus-infected host cells, the areas subsequently damaged by the virus appear smaller and, in some cases, are fewer in number. This implies that tea tree oil is capable of preventing virus replication, but further work is required to characterise this and to identify those components responsible for the effect.
Contact: Christine Carson or Professor Tom
Riley, Queen Elizabeth II Medical Centre, Nedlands WA 6009; Ph (08) 9346
3288; Email ccarson@cyllene.uwa.edu.au or Ph (08) 9346 3690; Email triley@
cyllene.uwa.edu.au; Fax (08) 9346 2912.
Last updated: 11 August 1999
Copyright © RIRDC
http://www.rirdc.gov.au/pub/newsletters/tea-tree-oil/july99.htm