Are Lavender and Tea Tree Oils estrogenic?

There’s a bit of a monster pesticide-resistant lice epidemic going around New York City, it seems like every school near us is infested. Last week, a third of my younger daughter’s class had lice. We didn’t.

Besides regular comb outs and wearing their hair up or in braids, we’ve been applying aromatic oils to our daughters’ heads before school. The mix of oils was recommended by a friend:

  • Tea tree, lemongrass & lavender in apricot kernel oil (25% dilution)
  • Put a couple of drops on your hands, rub palms together & then pat it on the hair.
  • Avoid contact with skin
  • Definitely avoid contact with eyes!

I mentioned the oils to some other parents and emailed it to the class. This morning the classroom smelled like tea tree oil.

But one parent mentioned some concern about estrogenic qualities of lavender and tea tree oils. This was troubling me so I did some research. Check out the most thorough essential oils guide

From what I found, the concern about tea tree and lavender originated with this 2007 observational study published in The New England Journal of Medicine (NEJM):

Prepubertal Gynecomastia Linked to Lavender and Tea Tree Oils

NEJM received several critical letters about the study which should be read too.

This was foremost an observational study, and the author’s conclusions seem loosely drawn from the results of three cases. (Gynecomastia is enlarged breasts in males) From their abstract:

We investigated possible causes of gynecomastia in three prepubertal boys who were otherwise healthy and had normal serum concentrations of endogenous steroids. In all three boys, gynecomastia coincided with the topical application of products that contained lavender and tea tree oils. Gynecomastia resolved in each patient shortly after the use of products containing these oils was discontinued.

First issue with the study is that not all three cases were exposed to tea tree and lavender, here’s what they mention in the text:

  • patient 1: “healing balm” containing lavender oil
  • patient 2: regular use of styling gel and shampoo containing tea tree and lavender oils
  • patient 3: lavender scented soap and occasional lavender lotions

Only one of the three of their observed subjects even recorded contact with tea tree oil.

As pointed out in the letters, there’s virtually no mention of dietary factors. Soy is known to have estrogenic effects and processed soy products are in everything these days.

Experiments using breast cancer cells to measure estrogenic effects seem to only vaguely apply to gene-expression in boys.

Both oils stimulate ERE-dependent luciferase activity in a dose-dependent manner, with the maximum activity observed at 0.025% volume per volume (vol/vol) for each oil, corresponding to approximately 50% of the activity elicited by 1 nM 17β-estradiol. Treatment with higher doses of the oils was cytotoxic.

The most extreme numbers were collected at the maximum possible oil dose before the cells they were treating were poisoned so much they died. I have no idea what that dosing would be to a human, but I suspect there’d be significant physical reaction before getting to that point.

Presenting their findings as “Average fold increase above control” without the actual numbers can be suspect. An increase from 0.02 to 0.06 is a three-fold increase, but still relatively insignificant.

Also, the delivery vehicle used in testing, dimethylsulfoxide, is suspected of having estrogenic effects:

Our data show that DMSO-induced significant increase in ERα, ERβ, Vtg and Zr-protein genes in a time-dependent manner. Indirect ELISA analysis showed a time-specific effect of DMSO. The use of DMSO as carrier solvent in fish endocrine disruption studies should be re-evaluated.

Most tea tree oil studies in PubMed seem to be related to its anti-fungal qualities or efficacy as a delivery vehicle for topical medications. I did find one study which looked at transdermal absorption of tea tree oil and found that very little passes through the skin:

…only a small quantity of TTO components, 1.1–1.9% and 2–4% of the applied amount following application of a 20% TTO solution and pure TTO, respectively, penetrated into or through human epidermis.

I believe this study looking at the effects of dietary soy proteins on tumor growth demonstrates greater estrogenic effects of dietary soy protein isolate than the tea tree oil study showed with direct in vitro exposure.

Microsoft is in trouble

Amazing how times change:

Missouri School of Journalism Laptops 2 Missouri School of Journalism Laptops

Originals found here, via Shawn King on Twitter

Thoughts on “An Education on Good Education”

Rather than IM the hell out of Marjorie about her latest column, “An Education on Good Education” I thought I’d put my thoughts down here and link it (and digg her too).

This is one of those columns where Marjorie was on fire, there are too many good quotes to pull them all, but here are some of my favorites:

Remember the column I did, back in the Pleistocene era, making fun of parents who obsessed about getting their kids into the 92nd Street Y preschool? This is the column where I eat that column. …

But: I now understand the fear that one’s child won’t get a good education if one doesn’t go to the mat for it.

I would add that your child won’t get a good education relying only on school, which I’m pretty sure Marjorie would agree with.

But when your 4-year-old tells you, The most important thing about school is no matter how hard someone hits you, it’s wrong to hit back, you know she’s going somewhere else for kindergarten.

WTF is our children learning?

Josie is a few months older than Lila, and so she missed the Dept. of Ed cutoff regarding which year. Ironically, or something, had Josie gone to private school, which use a different calendar, they would have been in the same year.

We reapplied to The Neighborhood School. It had been my first choice last year, with the small size, progressive philosophy and mixed-age classrooms I liked in the school Josie got into, but with higher test scores and a long-established and well-respected principal. Last year, Josie’s name wasn’t picked in the lottery. (The school is kept balanced deliberately by race, reflecting roughly the same demographic breakdown as the neighborhood: something like 31% white, 21% black, 32% Latino and 18% Asian.)

First, there is some seriously questionable selection going on with these “Lotteries.” I’m not going to go into accusations I can’t backup, but a significant increase in transparency would be a good thing for all the schools.

Second, racial quotas: I don’t like them, but in this case it’s almost amusing how badly they’ve played out. This is the year the September 11th Baby Boom lands in public school Pre-K. The population of four year-olds in New York City has ballooned, with most born sometime after May 2002. I find it deeply poetic that humanity’s innate reaction to death and carnage is babies.

In our neighborhood, the population demographic has fully inverted. The progeny of the hipsters and young, formerly childless couples who lived in the East Village don’t fit the Department of Ed’s out-of-date demographic. The result is that Neighborhood School, everyone’s first choice, got that demograpic. Earth School probably got close to the demographic “ideal” since it’s usually the number-two choice (despite having an upside-down picture of their namesake planet in their science room).

Which brings us to our school, East Village Community School. The Pre-K classes are overwhelmingly white and female. As racial and class boundaries seem to track closely in our rapidly gentrifying neighborhood, the DOE’s imposed diversity program will likely cause a drastic upending the funding balance between this group of schools. My biggest hope is that they don’t break things more by trying to fix these new imbalances.

Department of the Board of Education?

The official New York City Department of Education website is

Several websites and email addresses belonging to the New York City Department of Education (NYCDOE) still use an acronym presumably leftover from their days as the NYC Board of Ed (NYCBOE). It’s easy to see why this is a problem when shown side-by-side in lowercase: (half-working url for Department of Education) (half-working eChalk site)

How much email has been lost because of that little letter-flip?

The old website for the NYC Department of Education, redirects to