Products Containing Lavender Oil Linked to Breast Growth in Boys

The condition, called gynecomastia, cleared up once they stopped using the products.

By Ed Edelson
HealthDay Reporter
Wednesday, January 31, 2007; 12:00 AM

Copyright © 2007 ScoutNews, LLC. All rights reserved.

WEDNESDAY, Jan. 31 (HealthDay News) -- Dr. Clifford Bloch, a pediatric endocrinologist at the University of Colorado, encountered three unusual patients last year: young boys who were growing breasts.

Aside from their gynecomastia, as the condition is called, there seemed to be nothing else unusual about the boys, who were 10, 7 and 4 years old. But Bloch soon picked up a common thread. All were using products containing lavender or tea tree oil -- a "healing balm" in one case, lavender-scented skin lotions and soap in another, and shampoo and hairstyling gel containing lavender oil in the third.

Bloch was "sharp enough to pick up on the idiopathic [unusual] nature of the condition," said Kenneth Korach, chief of laboratory reproductive and developmental toxicology at the National Institute of Environmental Health Sciences. Korach also worked on the three cases and is an author of a report on the boys in the Feb. 1 issue of the New England Journal of Medicine.

Results of the study were first reported last June at the annual meeting of Endocrine Society, in Boston.

"I don't know how many pediatric endocrinologists would have the time or interest to delve into the source of this type of condition," Korach said.

After discussing the cases with Bloch, Korach and his colleagues started experiments in which human cells were exposed to the oils. The idea was to see whether those oils mimicked the effects of the female hormone estrogen, which stimulates breast tissue growth, or block the activity of the male hormone androgen, which inhibits growth of breast tissue.

The tests showed that the oils affected both the male and female hormones. "This combinatorial activity makes them somewhat unique as endocrine [hormone] disrupters," Korach said.

When the boys stopped using the oil-containing products, their breasts returned to normal. But how many other boys may be experiencing the same abnormal pattern because of the products they put on their skin or hair?

"It's probably a relatively rare occurrence," Korach said. "We have to await further study or analysis. Now that it is coming out in this publication, other clinicians may hear about it."