Bad Shampoo for Boys?
The Suspicion A preliminary finding presented at the Endocrine Society's conference last month could prompt parents to read product labels more closely. The unpublished research suggests that shampoos, soaps and body lotions containing lavender and tea tree oils -- commonly added for their aromas and marketing cachet -- may cause hormonal imbalances and breast growth in young boys.
The study was carried out by scientists at the National Institute of Environmental Health Sciences (NIEHS) after a Denver pediatric endocrinologist reported abnormal breast development, known as gynecomastia, in five boys, aged 4 to 7, who used products containing the oils. The symptoms subsided after the boys stopped using the products.
The Test NIEHS researchers Derek Henley and Kenneth Korach tested the effects of lavender and tea tree oils on human breast cancer cells. They found that both oils mimicked estrogen (a hormone that promotes the development of female breasts) while reducing the activity of androgens, which inhibit such growth. "Boys are getting a double hit," said Korach, who added that this hormonal imbalance may explain the Denver cases.
The Caveat Steven Dentali, vice president of scientific and technical affairs for the American Herbal Products Association, a trade group, said it's premature to worry, given the paucity of clinical evidence and many questions that the lab work left unanswered. Still unknown, he said, are the tolerable limits of use and the specific compound in these oils that may be producing the observed effects.
While they acknowledged that more studies are needed, the NIEHS investigators said they hoped their preliminary research would alert doctors and parents to the possible association. They advised parents to discuss any fears about herbal oils with their pediatrician. Parents who notice potentially related symptoms in their boys should also report them promptly to their physician.
-- Jeffrey G. Ghassemi