Researchers from the Institute of Environmental Health Sciences have found that essential oils possess a diverse amount of chemicals and should be used with caution because some of these chemicals are potential endocrine disruptors.
The chemicals found in tea tree and lavender are referred to as ‘endocrine-disrupting’, which means they can interfere with hormones and their actions in the body. They speculate that these chemicals can cause boys and men to develop gynecomastia or man breasts.
They used “in vitro, or test tube, experiments” And, “the researchers applied these chemicals to human cancer cells to measure changes of estrogen receptor- and androgen receptor-target genes and transcriptional activity.” (1)
Whether the same effect would happen in real life use (the essential oils diluted in carriers or in used body products) hasn’t been comprehensively studied.
Here’s the response from the leading researcher on essential oil safety. Robert Tisserand literally wrote the book on essential oil safety.
If you’re concerned about male breast tissue you should see your doctor.