Lavender and tea tree oils

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Lavender and tea tree oils may cause breast growth in boys

 

A study published in this week's issue of the New England Journal of Medicine

suggests that repeated topical use of products containing lavender oil

and/or tea tree oil may cause prepubertal gynecomastia, a rare condition

resulting

in enlarged breast tissue in boys prior to puberty, and for which a cause is

seldom identified.

Researchers at the National Institute of Environmental Health Sciences

(NIEHS), part of the National Institutes of Health (NIH), confirmed in

laboratory

studies what a pediatric endocrinologist at the University of Colorado at

Denver and Health Science Center's School of Medicine suspected after

diagnosing

three of his young male patients with prepubertal gynecomastia. The

researchers found an association between the use of products containing these

oils

and the rare disorder, but cautioned more research is needed. At this point,

the findings are only applicable to young males with unexplainable enlarged

breasts who are regularly using products containing these essential oils.

" We want to encourage doctors who may be seeing patients with gynecomastia to

ask their patients about the products they are using. Patients with

prepubertal gynecomastia may want to consider reducing the use of products that

contain these oils, " said Ken Korach, Ph.D., chief, Laboratory Reproductive and

Developmental Toxicology at NIEHS and author on the study. " Although we found

an association between exposure to these essential oils and gynecomastia,

further research is needed to determine the prevalence of prepubertal

gynecomastia in boys using products containing lavender and tea tree oils.

Results of

such epidemiological studies are important to tell us how strong the

association is between topical application of the oils and prepubertal

gynecomastia "

The three otherwise healthy Caucasian boys, ages four, seven and 10 years,

had normal hormonal levels when they were diagnosed with gynecomastia by

Clifford Bloch, M.D., in Colorado. All had either used lavender-scented soap and

skin lotions, or shampoos or styling products that contained tea tree oil and

lavender oil as ingredients. In each case, several months after the suspected

products were discontinued, the gynecomastia had subsided or resolved.

After Bloch discussed the cases with Korach, the NIEHS researchers conducted

experiments using human cells to determine if the oils mimic the effects of

estrogen, the female hormone that stimulates breast tissue growth, or

inhibited the effects of androgen, the hormone known to control masculine

characteristics and inhibit the growth of breast tissue. The researchers tested

the

ability of the oils to modulate or inhibit gene expression.

" The results of our laboratory studies confirm that pure lavender and tea

tree oils can mimic the actions of estrogens and inhibit the effects of

androgens, " said Korach. " This combinatorial activity makes them somewhat unique

as

endocrine disruptors. "

Bloch said the laboratory studies support his hypothesis. " Since there was no

identifiable cause for prepubertal gynecomastia in the three patients we

reported, we speculated that environmental factors might be contributing to

their condition. Together, the case histories and NIEHS in vitro studies provide

support for our hypothesis that topical exposure to lavender and tea tree

oils likely caused gynecomastia in the three patients. "

The oils did not alter the levels of the usual forms of circulating estrogens

and androgens in the boys. " We do not anticipate any long term effects on

hormonal levels, " said Derek Henley, Ph.D., the lead NIEHS author on the study.

It is unknown whether the oils have similar endocrine disrupting effects in

prepubertal girls, adolescents or adults.

" This study clearly demonstrates how clinical observations can be supported

by basic science research, " said NIEHS Director David A. Schwartz, M.D.

These essential oils might now be considered endocrine disruptors since they

appeared to have caused an imbalance in estrogen and androgen signaling.

Endocrine disruptors are naturally occurring compounds or synthetic chemicals

that may interfere with the production or activity of hormones of the endocrine

system leading to adverse health effects.