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Regular exposure to lavender oil or tea tree oil may cause young boys to develop prepubertal gynecomastia. It is a condition that leads to abnormal breast growth, Science Daily reported.
Experts believe that key chemicals in the plant-derived oils act as chemicals that disrupt endocrine. The results of the study will be presented on Monday at ENDO 2018, the 100th annual meeting of the Endocrine Society in Chicago.
Interferes with hormones
J. Tyler Ramsey, a post-baccalaureate research fellow at the National Institutes of Health, noted that society generally considers essential oils as safe. However, he pointed out that it possesses a diverse amount of chemicals and must be used with caution because some of the chemicals are potential endocrine disruptors.
He explained that an endocrine-disrupting chemical is one in the environment that interfered with hormones and its action in the body. Although male gynecomastia before puberty is rare, there have been a growing number of cases reported.
Forbes reported that three otherwise healthy pre-pubertal boys with normal blood levels of estrogen and androgens developed larger breasts after using products with lavender or tea tree oil. The gynecomastia went away after the three boys stopped using the oils.
Three more cases of boys with prepubertal gynecomastia had been reported in a publication in the Journal of Pediatric Endocrinology and Metabolism. The three had been exposed to lavender oil for long periods of time. Cologne was the source for two of the boys, although Forbes presumed that it is the people around the boys who used the cologne and not the boys.
The reports coincided with topical exposure to lavender and tea tree oil. The condition went away after the boys stopped using the oil, Ramsey said. The two oils are alternatives for medical treatment, personal hygiene, cleaning products, and aromatherapy. Among the various consumer products with lavender and tea tree oil are soaps, colognes, lotions, shampoos, hair-styling products, and laundry detergents.
Lavender and tea tree oil have estrogenic and anti-androgenic activities, meaning it inhibits testosterone by completing or hindering the hormones that control male characteristics that could affect puberty and growth, Kenneth Korach, a researcher at the NIEHS, said.
Ramsey and his team, under the direction of Korach, went one step ahead. They selected for analysis eight components that are common and mandated for inclusion in the oils from hundreds of chemicals that comprise lavender and tea tree oil.
There are four common chemicals in the two oils -- eucalyptol, 4-terpineol, dipentene/limonene, and alpha-terpineol. Four chemicals were in either oil. These were linalyl acetate, linalool, alpha-terpinene, and gamma-terpinene.
The researchers then applied these chemicals using in vitro, or test tube, experiments to human cancer cells to measure changes of estrogen receptor- and androgen receptor-target genes and transcriptional activity. They reported that all eight chemicals showed varying estrogenic and/or anti-androgenic properties. Some showed high or little to no activity. The changes they observed were consistent with endogenous, or bodily, hormonal conditions which stimulate gynecomastia in prepubescent boys.
Ramsay said because lavender and tea tree oil pose potential environmental health concerns, these should be investigated further. He noted that many of the chemicals that the researchers tested appear in at least 65 other essential oils which are available without a prescription and are not regulated by the US Food and Drug Administration.
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Unexpected ant-male hormone effects
The findings have confirmed why an individual using the oil containing these chemicals may develop breast tissue, Ieuan Hughes, an emeritus professor of pediatrics at the University of Cambridge, said. He noted that the anti-male hormone effects are rather unexpected, but he declined to comment further without the data.
But he pointed out that not everyone exposing themselves to such oils has adverse effects. He said it is possible that there are particular individuals who may be more sensitive to the effects of the chemicals, or are probably using the products in excess. Hughes pushed for the regulation of these products, BBC reported.
Dr. Rod Mitchell, an honorary consultant pediatric endocrinologist at the Queens Medical Research Institute in Edinburgh, said that the research is important in establishing a possible mechanism for the suggested link between gynecomastia and exposure to the two oils. But he said that there are important factors that must be taken into account when interpreting the results. Mitchell noted that the tests were conducted in cancer cells. It may not represent the situation in normal breast tissue.
Mitchell stressed that the concentration dose to which the cells are exposed may not be equivalent to exposure in humans. He noted the complex relationship between estrogen, testosterone, and other hormones in the body which cannot be replicated in these experiments.
There is not sufficient evidence to support the idea that exposure to tea tree and lavender oil contain products that cause abnormal breast growth in children, Mitchell said. He said more epidemiological and experimental studies are needed.
[researchpaper 리서치페이퍼=Vittorio Hernandez 기자]