New Zealand producer of Tea Tree oil from Melaleuca alternifolia
Article printed in Organic NZ magazine, May 2007 issue
Media reports surface regularly speculating on the possible adverse effects from using plant based extracts as healing agents. As consumers we need to keep informed about safety issues but we also need to know that such ‘health scares’ are based on the results of sound independent scientific research, diagnosis, analysis and techniques.
‘We investigated possible causes of gynecomastia in 3 otherwise healthy prepubertal boys which coincided with the topical application of products that contained lavender and tea tree oils. We conclude that repeated topical exposure to lavender and tea tree oils probably caused prepubertal gynecomastia in these boys.’
From the summary of the original report co-authored by D Henley, N Lipson, K Korach, C Bloch
A study published in the February 1, 2007 issue of the New England Journal of Medicine (NEJM) purported to find that two commonly used aromatherapy essential oils (lavender – lavandula angustifolia and tea tree – Melaleuca alternifolia) have been linked with temporary breast enlargement in three boys, aged four, seven, and ten years, a condition known medically as prepubertal gynecomastia. This is a rare condition, which prompted a search for an outside source of estrogen. It is unknown whether the oils could have similar effects in prepubertal girls, adolescents or adults.
The researchers evaluated lavender oil, which was the component found in all the products used by the patients, and tea tree oil, that was found in one of the products. “Other components in these products may also possess this activity but those components were not tested because we chose to evaluate only the components that were found in all the products used by the patients (lavender oil) and a chemically similar component that was found in some of the products (tea tree oil)”. [The actual components of lavender oil and of tea tree oil are almost totally chemically distinct from each other and it is unlikely that they would have similar effects. The paper claims the opposite. The obvious question arises as to the identity of the component(s) responsible for the effects identified.]
The researchers said it was possible that the boys’ breast growth may have stemmed from other causes and described exposure to lavender and tea tree oils and gynecomastia in young boys as ‘an association’, but stopped short of describing the relationship as ‘cause and effect’.
Although the symptoms apparently disappeared once these products were discontinued, the possibility that all three cases may be due to some other material in these boys environment was not investigated. All three affected boys lived in the Denver area, yet no other environmental or health factors were considered. Many common products in the environment such as petroleum-derived perfumes, pesticides and plastics, have estrogen-like effects. The fraternal twin of one of the boys apparently using the same materials was not affected.
One boy used a skin balm with lavender oil, another used lavender soap and lavender-scented skin lotion and the third used a hair gel and shampoo with unstated amounts of lavender and tea tree oil. The composition of the shampoo that was used is a well-formulated product of less than 1% tea tree oil. The possibility of skin absorption is very low from the usage of styling gel (as the gel is applied to the hair, not scalp). Shampoo, hair gel and soap are rinse-off products. Only the ointment is a leave-on skin treatment.
Over the past 21 years the two leading companies supplying tea tree products, Melaleuca Inc and TP Health Ltd, have sold over 150 million units of product containing tea tree oil. Both companies maintain meticulous adverse event reporting records. At the time of writing there has never been a single case of prepubertal gynecomastia reported to either company. Even in the last 10 years, consumer complaints about 0.002% of products sold have mainly related to product packaging.
In an attempt to prove an association between these oils and prepubescent breast formation, laboratory tests were carried out using both essential oils on human breast cells. The researchers reported that tests showed both oils may boost estrogen, the female hormone that stimulates breast growth, and inhibit androgens, the hormones that inhibit breast tissue growth. According to Dr Noel Porter, one of New Zealand’s leading plant extracts research scientists, ‘ the laboratory tests involved highly sophisticated and artificial in-vitro bioassays, using a cell line not found in normal people’.
The quantities of oil used in the cell culture were vastly greater than would be possible to achieve by normal cosmetic application of products yet there was no acknowledgement of this.
Skin penetration studies for tea tree oil conducted at the University of Queensland by Dr Sheree Cross (unpublished) have clearly shown that ‘only extremely small amounts of 3 of the over 100 components found in tea tree oil have been found to penetrate the surface of the skin and that evaporation removes over 90%, so that any estrogen receptor activity by tea tree oil in vitro is not relevant to topical application of tea tree products’. This may well be true with lavender as well. There is nothing in the literature that indicates that these components (terpinen-4-ol, alpha-terpineol and 1,8-cineole) have estrogenic receptor activity in-vitro or in-vivo.
Dr Porter challenged the authors of the paper to take their findings further, and show that ‘if the activity identified could be verified there is the possibility of both these oils being of use in hormone replacement therapy for menopausal women, or as an adjunct to prostate cancer therapy in males’.
Estrogenic Activity of Plants and Essential Oils
Many plants possess sex hormonal activity and a number of classes of compounds possess estrogenic activity: 4410 plants are categorised as emmenagogues, 2630 as abortives, 1249 as possessing contraceptive properties, 1275 as having aphrodisiac actions and 432 linked to fertility promotion.