Pre-pubertal boys who regularly use products containing lavender oil or tea tree oils may develop breasts, a study says, but the effects fade when they stop using the products.
Lavender and tea tree oil are sold over the counter in their 'pure' form and are present in an increasing number of commercial products including shampoos, hair gels, soaps and body lotions.
Derek Henley at the National Institute of Environmental Health Sciences (NIEHS) in the US and his colleagues investigated reports of three healthy boys who hadn't started puberty and who developed breasts.
The boys had developed the condition, called gynecomastia, after using products containing lavender or tea tree oils, the online edition of health magazine WebMD quoted researchers as saying.
One of the boys was four years old. His mother had applied "healing balm" containing lavender oil to his skin shortly before the boy's breasts developed and grew to about an inch in diameter.
Another boy was 10 and had been using a hair-styling gel daily that contained lavender and tea tree oils.
The third boy - nearly eight - had been using lavender-scented soap and skin lotions. His fraternal twin had used the same products but didn't develop breasts. The boys' breasts receded within months after they stopped using the products, the researchers said.