Breast growth in boys blamed on cosmetics

James Randerson, science correspondent
Thursday February 1, 2007

Cosmetics containing lavender and tea tree oil can disrupt the hormonal development of pre-pubescent boys causing them to grow breasts, doctors say in a warning that follows three American boys experiencing the rare condition after they used gels, shampoos or lotions containing the essential oils.
The researchers say they do not yet know which chemicals in the oils caused the changes. Once identified these substances might need to be removed from products designed for children.
"If you use these products on your child and you see changes in their body talk to your doctor or paediatrician," said Kenneth Korach, at the US National Institute of Environmental Health Sciences, in Maryland.
Although six in 10 boys experience some temporary breast enlargement during puberty, it is very rare for pre-pubescent boys to begin developing breasts, a condition called gynecomastia. Scientists know this is caused by a disruption of sex hormone signals to breast tissue, but it can have a variety of causes.
The researchers began to suspect lavender and tea tree oil after Clifford Bloch, a paediatrician at the University of Colorado School of Medicine, examined the cases of three boys, aged four, seven and 10. "We speculated that environmental factors might be contributing to their condition," he said. The link was that the parents had given the children products containing the essential oils, including a skin balm with lavender oil, a gel and shampoo with lavender and tea tree oil, lavender soap and lavender-scented skin lotion.
To see if the oils were the culprits, the team tested lavender and tea tree oil on human breast cells in the laboratory. They report in the New England Journal of Medicine that the oils stimulated breast cells to produce oestrogen and inhibit male sex hormones. The breasts of all three boys returned to normal a few months after they stopped using the cosmetics.
"We want to encourage doctors who may be seeing patients with gynecomastia to ask [them] about the products they are using," said Dr Korach.

Fonte: http://www.guardian.co.uk/medicine/story/0,,2003340,00.html - 01/02/07