A series of three cases of breast enlargement in prepubertal boys led clinicians to search for a cause (1). They discovered that each of the boys had been using topical applications of products that contained lavender and tea tree oils. The symptom resolved when the boys stopped using these products.
Particulars of the cases included a 4 year-old boy whose mother applied an herbal lotion containing lavender, a 7 year-old boy who used a lavender-scented soap and skin lotion, and a 10 year-old boy who used a shampoo and styling gel that contained tea tree oil and lavender. Breast swelling is not a normal symptom in young boys and usually is caused by an internal or external estrogen source.
This led the clinicians to research the effects of the oils on human cells. They tested the two oils on breast cancer cells with estrogen and androgen receptors. They found that the oils did have estrogenic effects and also blocked the male hormone androgen, both of which could have caused the breast swelling in these boys.
Lavender (lavandula) and tea tree oil (melaleuca) are often added to lotions and bath products for children. Parents should be aware of the estrogen-like effects of these, and many other products. Petroleum derived perfumes and pesticides, plastics, and soy products all exhibit estrogen effects. The skin is a very good absorbent membrane for drugs and chemicals, so parents need to be cautious about the products they use on their children’s skin. Babies are especially susceptible to the disruptive and toxic effects of drugs and harmful chemicals applied to the skin in lotions and sunscreens, because their immature livers have difficulty metabolizing these chemicals. Parents should therefore use safe sunscreens (zinc oxide), organic shampoos, lotions, and soaps, and stay away from prolonged use of products that contain lavender and tea tree oil.
Henley DV, et al. Prepubertal gynecomastia linked to lavender and tea tree oils. New England Journal of Medicine Feb 1, 2007; 356:479-485.
Defending tea tree oil
In response to the newsletter article I wrote reporting on the suspected connection between lavender and tea tree oils and the occurrence of breast swelling in three young boys, I received the following text from a manufacturer of tea tree oil products. I have edited the response and not attributed it, because it was not intended for mass distribution. However, I feel it is important to present as many perspectives as possible on this issue so that consumers can make informed decisions.
Here is the response.
When we first received word of this study, we contacted Dr. Derek Henley, the lead author of the research, who works at the National Institute of Environmental Health Sciences. Dr. Henley told us that this issue first came to his attention when Dr. Clifford Bloch, a pediatric endocrinologist in Denver, Colorado, reported that he had treated three young boys within a short period of time who had symptoms of prepubertal gynecomastia (enlarged breast tissue in young boys). Bloch thought that was unusual because he normally only sees about one case of prepubertal gynecomastia a year. In the course of his treatment of these patients, Bloch discovered that all of the boys had been using products that contained lavender oil. Bloch told us that the source of lavender oil for one of the boys had been a Paul Mitchell hair gel and shampoo that contained both lavender oil AND tea tree oil. For some unknown reason Bloch decided to include tea tree oil in his write-up even though lavender oil was the only common ingredient used in the products of all three boys. We did a chemical analysis of the Paul Mitchell hair gel and shampoo in question and found that tea tree oil was barely detectable in the hair gel and a very low concentration in the shampoo.
When they received this information from Bloch, Henley and Kenneth Korach, both researchers at the National Institute of Environmental Health Sciences, performed test tube experiments of the effects of lavender oil on breast cancer cells. They also decided to test tea tree oil because of Dr. Bloch’s request. They observed that both oils exhibited estrogen-like qualities on the cells. At the annual meeting of the National Endocrine Society held in Boston in June 2006, Henley reported the results of the research, which was subsequently published on February 1, 2007. What Henley’s report failed to mention is that there are literally thousands of harmless natural oils and other natural plant substances that exhibit similar estrogen-like qualities when applied directly to a cell culture. Just a few common examples of products that have similar effects as tea tree oil in similar tests are: soy, hops, garbanzo beans, red clover, lentils, flaxseed, sunflower seeds, alfalfa sprouts, licorice, and ginseng.
Dr. Henley told us that while he was being interviewed by reporters about the report, he had the definite impression that they were trying to get him to say that lavender oil and tea tree oil cause gynecomastia so that they could publish a headline that these products should not be used. Henley told us that he was concerned about how the stories had come out as they just took portions of what he said instead of publishing everything he said. Henley emphasized to us that the research does not conclude that either lavender oil or tea tree oil are the direct cause of the gynecomastia in the young boys, but that there may be a correlation. He pointed out that the only common ingredient among all of the products used by the patients was lavender oil and that only one boy had used a product that contained both lavender oil and tea tree oil. In his report Henley cautioned patients of prepubertal gynecomastia to avoid repeat exposure to these essential oils, but in our phone interview he said there is not nearly enough evidence to indicate that people should stop using products with lavender oil or tea tree oil, even young boys.
We believe that these news reports based on this very simple cell culture assay are very misleading.
First, the study does not support a scientific conclusion because there is no connection between the cell culture on tea tree oil and the one boy who used a hair gel and shampoo containing tea tree oil. Both products also had lavender oil, and when tested in a lab the tea tree oil content was virtually undetectable in the hair gel and at very low concentrations in the shampoo, which Dr. Henley informed us was Paul Mitchell Tea Tree Shampoo.
Second, thousands of plant-derived compounds have the same estrogen-like impact in a cell culture, including food products that millions of people around the world ingest every day like soy, hops, garbanzo beans, red clover, lentils, flaxseed, sunflower seeds, alfalfa sprouts, licorice, ginseng and many others.
Third, rather than use the coincidental story of a single boy, it seems that it would be more appropriate and much more responsible to report the results of millions of users of Melaleuca Oil. Considering the millions of products sold with tea tree oil each year, if there was any truth at all to this unsupported theory it seems that Melaleuca would see a common occurrence of prepubertal gynecomastia in young boys. Instead we have never received a single report! Not one! Ever!
Fourth, all 3 boys lived in the Denver area, yet no other environmental or health factors were considered.
Fifth, the study reports that there are other components in these products that may contribute the gynecomastia that were not tested, including other essential oils in the products the boys were using. The only common essential oil in these products was lavender oil, yet the researchers chose to include tea tree oil in their report and tested no other ingredients in these products.
It seems very odd to us that tea tree oil was even mentioned in this story. It appears that lavender oil is the only common substance used by the three boys in question. It appears that the only reason that tea tree oil was mentioned in the story was because the source of lavender for one of the three boys was Paul Mitchell Tea Tree Hair Gel and Shampoo. There does not appear to be any evidence whatsoever that the symptoms of that one boy had anything to do with tea tree oil.
It is absurd to us why, when one young boy presents with gynecomastia, and it is learned he used a Paul Mitchell shampoo and hair gel, it is suspected that tea tree oil caused his condition. That shampoo has many other ingredients other than tea tree oil, including lavender! In fact, all three boys had used products containing lavender . We can understand why lavender would be suspect, but it is an almost impossible leap of judgment to conclude that tea tree oil had anything to do with the problem.
That said, it is difficult to shut off or change a story once it gets started. Nevertheless, perhaps the most convincing data that we have is that after selling over 123 million bottles of product containing Melaleuca Oil, we have never had a single case of gynecomastia reported to us. It is apparent that the researchers in this case got more than a bit carried away in their effort to link tea tree oil to the story there appears to be no relationship whatsoever.