Lavender and tea tree oil could give men ‘moobs,’ new research suggests.
Scientists claim the natural oils, often added to shampoos and soaps, contain gender-bending chemicals that mimic the effects of the female hormone oestrogen.
Laboratory tests by researchers in North Carolina also showed the chemicals can hold back testosterone.
A link between the growth of abnormal breast tissue in boys – known medically as prepubertal gynecomastia – has been suspected for years.
Previous studies have suggested key molecules in the common plant-derived oils act as endocrine-disrupting chemicals (EDCs).
The latest findings, presented at the Endocrine Society’s 100th annual meeting in Chicago, add to the evidence.
Scientists claim the natural oils contain gender-bending chemicals that mimic the effects of the female hormone oestrogen
Study leader Dr Jeffrey Ramsey, of the National Institute of Environmental Health Sciences (NIEHS), said: ‘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.’
Lavender and tea tree oil are essential oils that have become popular in the US and the UK as alternatives for medical treatment, personal hygiene and aromatherapy.
They are found in soaps, lotions, shampoos, hair-styling products, cologne and laundry detergents.
An endocrine-disrupting chemical is one in the environment that interferes with hormones and their actions in the body.
Male gynecomastia occurring before puberty is relatively rare, but a growing amount of cases have been reported to coincide with exposure to lavender and tea tree oil.
Dr Ramsey said the condition went away after the boys stopped using the oil-containing products.
Researchers at the NIEHS earlier found laboratory evidence that lavender and tea tree oil have oestrogen-like properties – as well as blocking the male hormone testosterone.
Male gynecomastia occurring before puberty is relatively rare, but a growing amount of cases have been reported to coincide with exposure to lavender and tea tree oil
This means they compete or hinder the hormones that control male characteristics, which could affect puberty and growth.
From the hundreds of chemicals that comprise lavender and tea tree oil, Dr Ramsey and colleagues analysed eight components that are common and mandated for inclusion in the oils.
Four appear in both oils including eucalyptol, 4-terpineol, dipentene/limonene and alpha-terpineol.
WHAT ARE GENDER-BENDING CHEMICALS?
BPS was designed as a replacement for BPA after mounting concerns about the plastic compound’s effect on human health.
But, scientists now believe that BPS is also a hormone disruptor.
WHAT ARE THESE CHEMICALS?
So-called endocrine-disrupting chemicals are found in thousands of everyday products, ranging from plastic and metal food containers, to detergents, flame retardants, toys and cosmetics.
Bisphenol A (BPA) in polycarbonate plastic is used for hard reusable bottles and food containers.
Bisphenol S (BPS) can be found in personal care products, baby bottles and receipts.
WHAT DO THEY DO?
The invisible chemicals cause neurological and behavioral disorders including autism and ADHD.
They also affect IQ.
Their hormone effects may cause cancer, diabetes, male infertility and endometriosis.
The others were in either – linalyl acetate, linalool, alpha-terpinene and gamma-terpinene.
In laboratory experiments, the researchers applied these chemicals to human cancer cells to measure changes of oestrogen receptor-and testosterone receptor-target genes.
All eight chemicals demonstrated varying oestrogenic or anti-testosterone properties, with some showing high or little to no activity.
Dr Ramsey said these changes were consistent with endogenous, or bodily, hormonal conditions that stimulate gynecomastia in prepubescent boys.
He said: ‘Lavender oil and tea tree oil pose potential environmental health concerns and should be investigated further.’
Dr Ramsey warned many of the chemicals they tested appear in at least 65 other essential oils.
Essential oils are available without a prescription and are not regulated.
Dr Ramsey said the public should be aware of these findings and consider all evidence before deciding to use essential oils.
Alarm about the oils was first raised by scientists more than a decade ago. Three young boys grew breast tissue after exposure to lotions and shampoos containing lavender or tea tree oil.
It is not uncommon for boys to develop breast tissue during puberty or just after, but the boys affected by the plant oils were aged four, seven and 10.
The boys were otherwise normal, and lost the breast tissue within months of discontinuing use of the products.
Researchers who identified the oils as the cause of the abnormalities warned parents and doctors to beware of the effects of any toiletry products containing the oils.