Regular exposure to everyday products used by many people may be causing young men to grow breasts, a new study from the National Institute of Environmental Health Sciences suggests.
Eight chemicals used in alternative medicine and cleaning products around the world were found to be endocrine disruptors – chemicals that disrupt hormones in the body. Repeat exposure to the oil-based products could lead to prepubertal gynecomastia – breast development in boys and young men.
Male gynecomastia is a relatively rare condition, but cases have been increasing in prepubescent boys. This coincides with exposure to tea tree oil, commonly used as an "alternative" antiseptic, and lavender oil, used in "aromatherapy" or as an alternative sleep aid. Several boys, some as young as four, developed breast tissue after being exposed to the oils, leading to an investigation of the link some years ago.
However, if you think you can escape them because you don't go in for these kinds of alternative treatments, the oils are also found in soaps, lotions, hair products, cologne, shampoos, and laundry detergents.
Researchers examined the link between the oils and abnormal breast development by looking at component chemicals within the oils. They applied the chemicals to human cancer cells, and measured how estrogen and androgen hormone receptor genes within the cells were affected by the exposure. The study found that the chemicals did disrupt hormones within the cells, boosting estrogen and inhibiting testosterone, showing hormonal changes consistent with those that cause gynecomastia.
"Lavender oil and tea tree oil pose potential environmental health concerns and should be investigated further," lead investigator J. Tyler Ramsey said in a statement.
"Our society deems essential oils as safe. However, they possess a diverse amount of chemicals and should be used with caution because some of these chemicals are potential endocrine disruptors."
Several of the chemicals tested in the study can also be found in at least 65 other essential oils that are available without prescription, and unregulated by the FDA. Researchers say that further testing is needed to better establish the link.
"The tests are conducted in cancer cells, which may not represent the situation in normal breast tissue," Dr Rod Mitchell, honorary consultant pediatric endocrinologist at the Queens Medical Research Institute in Edinburgh, told BBC News, calling for a larger-scale study.
"The concentration (dose) to which the cells are exposed may not be equivalent to exposure in humans."
Fortunately, the researchers found that the effect could easily be reversed by discontinuing use of the chemical-containing products. The findings were presented at the Endocrine Society's 100th Annual Meeting and Expo.