Budding Problems: Essential Oils as Endocrine Disruptors

As endocrine science unlocks more secrets of endocrine disruptors, new common household items are being scrutinized for their safety. A recent study from The Journal of Clinical Endocrinology & Metabolism reveals how lavender oil – a staple in Hispanic culture – could possess estrogenic and antiandrogenic consequences. 

In some U.S. Hispanic communities, liberal use of a certain scent, called agua de violetas, to perfume babies is common. It is so common, in fact, that it is also known as the “baby cologne,” although people of all ages are known to use it.

When prepubertal gynecomastia began occurring with relative frequency in these communities, a link was established to the lavender oil–containing agua de violetas. Lavender oil as well as tea tree oil, as is now known, stimulates estrogen receptor activities.

Coming Up Lavender

In 2007, with the understanding that prepubertal gynecomastia is both rare and pathologic as opposed to the much more common pubertal gynecomastia occurring in up to 60% of males, Kenneth S. Korach, PhD, of the National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health in Research Triangle Park, N.C., and his team sought an environmental source of the estrogen that was likely to blame. From both case reports and in vitro studies, they determined that lavender oil and tea tree oil are estrogenic and antiandrogenic, thus disrupting hormone pathway signaling when routinely applied topically, as reported in NEJM.

Their findings let people know that, just because it is “natural,” lavender oil could be the source of some negative health effects in young boys.

Price of Oil

But Korach and team had more questions in the ensuing decade. “One of the comments that I remembered about the study was that both lavender and tea tree oil are mixtures and made of a number of components. We next wanted to identify what components in the oils might be mediating these hormonal effects, either as estrogen agonists or as androgen antagonists,” Korach explains.

When postbaccalaureate Intramural Research Training Award (IRTA) fellow J. Tyler Ramsey, D.O. candidate joined the lab at NIEHS, that’s just what he did, finding that the eight components analyzed and tested (eucalyptol, 4-terpineol, dipentene/limonene, alpha-terpineol, linalyl acetate, linalool, alpha-terpinene, and gamma-terpinene) have varying hormonal activity, but most had at least some. “For breast development, you need estrogen and/or you need something that blocks testosterone,” Ramsey says. “That’s why we looked at both of those aspects, and we were able to see that most of the components had some level of activity.”

“A lot of people use these types of products, and it’s unclear why just a small group of patients show this clinical condition. We don’t want to be alarmists and tell people they should quit using these products; they just need to be aware that there could be some consequences in susceptible individuals.” – Kenneth S. Korach, PhD, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, N.C.

Especially worrisome, many of these components are found in dozens of other so-called “essential oils,” that unwitting consumers assume are safe to use in everything from perfume, as mentioned, to other personal-care products like soaps, lotions, deodorants, and laundry detergents.

What About the Girls?

These mechanistic assays done in culture on cancer cells were just one part of the study Ramsey led. The other part of “Lavender Products Associated with Premature Thelarche and Prepubertal Gynecomastia: Case Reports and Endocrine-Disrupting Chemical Activities, published in November in The Journal of Clinical Endocrinology & Metabolism, as the title suggests, concerns four case studies, three prepubertal girls and one prepubertal boy showing signs of breast development and exposed to hygiene products containing lavender oil.

Until now, no one had looked at whether this endocrine disruption could affect girls, possibly because early breast growth in girls is easily mistaken for early puberty. Two clinicians, Ajanta N. Naidu, MD, of the Children’s Hospital of Orange County in Irvine, Calif, and Alejandro Diaz, MD, of the Nicklaus Children’s Hospital, in Miami, Fla, had noticed prepubertal thelarche in young girls using topical lavender oil products, and being familiar with the NEJM study, put two and two together and joined the team of investigators to determine if this lavender oil was again the culprit.

Diaz defines premature thelarche as “the development of breast tissue under the age of seven to eight years, resulting from a prior exposure to exogenous or endogenous estrogen, or to estrogenic substances.” The negative effects of premature puberty include an increased risk of developing breast cancer later in life, according to epidemiologic studies.

One girl age seven years was frequently exposurd to “Mi Tesoro Agua de Violetas,” a three-year-old girl was regularly bathed with “Baby Magic Calming Baby Bath Lavender and Chamomile” soap, and another seven-year-old was exposed to lavender oil through a diffuser she sat near at school. The one boy, age seven, was regularly exposed to “Crusellas Violet Water” cologne.

“When the children were on lavender oil, we were able to see some kind of breast development early on, and once the product was removed, it went away,” Ramsey says.

Natural Causes

Although Korach has now retired from active research, Ramsey would like to pursue an epidemiological study next. “We still are not sure if it’s a genetic component or whether Hispanics use lavender oil more than other cultures,” Ramsey says. “That kind of study is a good one to do at this point to figure out if there is a correlation with a certain population or not.”

According to Diaz, premature thelarche/gynecomastia related to lavender use is observed more frequently among Hispanic populations. “This is due to the very common use of colognes and perfumes that contain this substance, often beginning during infancy. This is particularly true among persons within the Cuban or other Caribbean cultures,” he says.  “It is also possible that there is a genetic predisposition to develop early thelarche/gynecomastia when exposed to lavender during early childhood. This may explain why not every child exposed to this substance develops breast tissue.”

Meanwhile, the team’s findings should resonate in clinicians’ day-to-day practices. “We thought that this study and the report of these cases would make clinicians, particularly pediatric endocrinologists who are going to be the type of physician mostly likely to see these patients, aware that when they cannot explain the cause of the condition, it may be something as simple as these types of products being used by the patients could be the root of it,” Korach says.

“With three papers on this issue, it might be warranted to add ‘are you currently using any essential oils?’ to the list. If someone were to come in with a heart problem, we would ask about their caffeine intake to see if that is a potential cause, likewise, a pediatrician should be asking about essential oils in the setting of premature thelarche or prepubertal gynecomastia.” – J. Tyler Ramsey, D.O. candidate, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, N.C.

“As future physicians, we are required to ask certain questions and pursue a diagnostic protocol when a patient comes in and presents with a certain symptom,” Ramsey says. “With three papers on this issue, it might be warranted to add ‘are you currently using any essential oils?’ to the list. If someone were to come in with a heart problem, we would ask about their caffeine intake to see if that is a potential cause, likewise, a pediatrician should be asking about essential oils in the setting of premature thelarche or prepubertal gynecomastia.”

Again, there’s irony in consumers believing they are making good choices in using “natural” products, but the fact is that very little research has been done on potential adverse effects. “St. John’s wort is a prime example,” Ramsey says. “That natural product was used frequently to treat depression, but when actual studies were done, its efficacy was questionable, and it has lots of other side effects. So, it’s an important question — what are these things actually doing?”

It’s also important to remember that, as Korach points out, the cadre of affected patients was quite small. “A lot of people use these types of products, and it’s unclear why just a small group of patients show this clinical condition,” he says. “We don’t want to be alarmists and tell people they should quit using these products; they just need to be aware that there could be some consequences in susceptible individuals.”

According to Diaz, most girls exposed to lavender-containing products do not develop premature thelarche. “Therefore, we cannot universally recommend avoiding use of lavender-containing products,” he says.

Horvath is a freelance writer based in Baltimore, Md. She wrote about the top endocrine science discoveries of 2019 in the December issue.

 

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