Naturally irritating: essential oils are just as bad as synthetic fragrances
Your skin can’t tell the difference if fragrance was created in a lab or extracted from a flower, writes Larissa Fedunik
“Nothing is black and white when it comes to fragrances…of course, synthetic fragrances are bad. Fragrances derived from essential oils can be wonderful. Fragrance isn’t categorically bad. I would really implore you guys to not be afraid of essential oil-derived fragrances.”
That’s Brooke DeVard of the delightful Naked Beauty Podcast, recorded in April 2020. While things are rarely black and white when it comes to fragrance, the science is unequivocally clear about fragrances derived from essential oils. They are neither wonderful nor categorically good.
In other words, be concerned — very concerned — about essential oils (and all fragrances, natural or not) in your skincare products.
What’s ‘natural’? What’s not?
For the sake of clarity, let’s define natural the way the International Fragrance Association (IFRA) does. Natural fragrances are complex compounds derived from natural aromatics that are extracted from plants without altering the chemical structure.
IFRA is the fragrance peak body, and it’s comprised of fragrance ingredient manufacturers and compounders. Among other activities, including advocacy, it has a self-regulatory role, assessing fragrance ingredients for toxicity and allergens. If it sounds problematic that the fragrance industry regulates itself, Kate Grenville’s 2018 book The Case Against Fragrance discusses this issue in depth.
But back to natural fragrances being made up of complex compounds. Let’s dwell on that for a moment. How complex, exactly?
Natural fragrances like essential oils are generally comprised of at least one hundred different chemicals. My bottle of rose essential oil perfume has printed on the bottle: “Ingredients: rose essential oil”. But in fact, rose essential oil is made up of 150 different chemicals [1]. This brings me to my first point:
1. Everything, including plants, is composed of hundreds of chemicals.
When it comes to the science of fragrance, aroma chemistry is complex. Flowers give off a complex mix of volatile organic chemicals (volatility refers to the ease with which a compound vaporises). This article gives a great overview of the chemicals responsible for the aromas of common flowers, but the smell of any flower is rarely down to just one single molecule.
The characteristic scent of rose, for example, is majorly influenced by a molecule called (−)-cis-rose-oxide — so much so that the compound was named after the flower. Another major contributor to the rosy scent is the beta-damascenone molecule. Other chemicals that are less influential, but still perceivable to our noses, include geraniol, nerol, (−)-citronellol, farnesol, and linalool.
Natural fragrance compounds can be extracted from flowers or other parts of plants by various means (you can read more in the definitions set out by the International Organization for Standardization). Essential oils are manufactured through techniques like water- or vapour distillation, mechanically processing citrus rinds, or by dry distillation. They are neither oils nor “plant tea”, but lipophilic (oil-loving) essences that consist of terpenes (a type of hydrocarbon) and aromatics, among other compounds. Plant extracts (a general term for any compound extracted from a plant, fragrant or otherwise) are usually obtained with solvents too (which may be completely or partially removed — more on solvents in ‘Natural vs synthetic’).
But what about synthetic fragrances — does a synthetic beta-damascenone molecule truly smell as sweet? Absolutely. The chemical formula of beta-damascenone is C13H18O. It’s an oxidised hydrocarbon that can easily be synthesised in a lab from a plethora of sources. You can get hydrocarbons from almost anywhere. Petroleum is a cheap and plentiful source, so synthetic fragrances are highly likely derived from petrochemicals. Sounds unappealing? Quite possibly, but it brings me to this fact:
2. It doesn’t matter to your skin where a chemical was derived from.
Synthetic beta-damascenone is exactly the same as beta-damascenone extracted from a rose. It may be synthetic, but it is truly nature-identical (…in everything but price. Five millilitres of rose essential oil may cost upwards of $300, likely because it takes 4000 kg of rose petals to produce one kg of rose oil.)
Of course, you won’t find isolated beta-damascenone molecules growing out of the ground like a rose bush. As Grenville points out in her book, synthetic fragrance compounds are present in cosmetics in a much higher concentration: you’re inhaling a vastly greater concentration of volatile compounds from sniffing a vial of rose oil instead of a bunch of roses. But essential oils are concentrated too, so calling them “natural” might be stretching things a bit. As Grenville writes:
“Essential oils are natural, in the sense they’re made from plants…But they’re also unnatural, in the sense that smelling them is like having the scent of hundreds of roses up your nose rather than just the scent of one.”
I like to think of essential oils as the sugar of the cosmetic industry. Sugar cane plants are perfectly natural. But you would have to chew your way through four huge, fibrous stalks of sugar cane to get the same amount of sucrose contained in one teaspoon of table sugar.
We’ll return later to the arguments for and against natural or synthetic fragrances. But setting aside concentration, I believe the most important distinction between natural and synthetic ingredients on cosmetic ingredient lists is this: natural fragrances are much more complex than synthetic ones.
3. Each synthetic ingredient is comprised of just one molecule, but each natural material contains a lot of different molecules.
The chemical compounds will differ greatly across each individual plant, even those of the same species. They depend on factors like the soil or climate the plant grew in, the harvest time, the production method (see description above), the storage conditions, and much more [2].
When you see “rose essential oil”, or “jasmine extract”, in your skincare or fragrance, keep in mind that that’s analogous to a list of 100+ chemical compounds. Unless your bathroom is fully equipped with a mass chromatography spectrometer, you’d never know exactly which.
Is that a little unsettling? Consider the following.
4. Of the hundreds of fragrance molecules in natural compounds, each one is a potential allergen.
How likely a potential allergen? Good question.
Allergan of the year
My first experience with contact dermatitis occurred shortly after trying a (fragranced) facial cleanser as a teenager. Mine was fairly mild (I developed flaky, irritated patches around my mouth), but contact dermatitis can be very serious indeed. Symptoms can also include redness, itching, dry or thickened skin and even blistering.
Allergic contact dermatitis (also known as contact allergy/dermatitis) is a type of contact dermatitis that usually develops within 48–72 hours of the allergen coming into contact with your skin. The unpleasant symptoms are caused by your body’s immune response as it makes antibodies in fight the allergen.
Dermatologists diagnose contact dermatitis using patch tests: they put a drop of liquid containing the suspected allergens on patches of scratched skin and assess the reaction. The American Contact Dermatitis Society nominates a chemical (or group of chemicals) every year as the “Allergen of the Year”. In 2007, the dubious honour went to “Fragrance”.
In about 16 per cent of contact dermatitis cases treated by dermatologists, fragrance is the culprit [3]. It’s impossible to quantify how many people experience contact dermatitis from fragranced products, as most don’t seek medical treatment. However, dermatologists estimate that between 1–4 per cent of the population has an allergic reaction to fragrances — and this incidence is increasing in industrialised countries [4]. An article published in the journal Dermatology puts this down to “the ubiquitous nature of fragrance of modern society”.
There are many, many fragrance ingredients (in 2018, the IFR listed 2947), but some of them are more irritating than others. Fragrance mix I is a common concoction to test for fragrance contact allergy. It contains eight chemical substances: isoeugenol, eugenol, cinnamic aldehyde, cinnamic alcohol, hydroxycitronellal, geraniol, a-amyl cinnamic aldehyde and oak moss absolute.
In 2005, fragrance mix II was added as an additional screening tool, consisting of citronellol, hydroxyisohexyl 3-cyclohexene carboxaldehyde (Lyral), hexyl cinnamal, citral, coumarin, and farnesol.
These fragrance chemicals are notorious for inducing contact dermatitis, but many more fragrance chemicals are allergenic. And because fragrances are considered to be trade secrets, you might not find them on ingredient labels.
Which fragrance chemicals are most allergenic?
In skincare and makeup, every ingredient must be disclosed and labelled in accordance with a country’s consumer laws (in Australia, this corresponds to the Trade Practices Consumer Product Information Standards for Cosmetics). But when it comes to fragrance, manufacturers don’t have to disclose the chemical compounds in the scent. It can simply be listed as “fragrance”, “perfume”, “flavour” or ”aroma”.
The European Commission Scientific Committee on Consumer Safety is highly concerned about the health effects of fragrance chemicals — not only because of their notoriety in provoking allergic responses, but due to other health risks. Since 2005, the Commission has restricted the use of 26 fragrance chemicals in cosmetics (these regulations only apply to products sold in the EU [5]). If any of these chemicals are present in concentrations greater than 0.01 per cent (in rinse-off products) or 0.001 per cent (in leave-on products), they have to be clearly stated on the ingredients list.
These 26 chemicals are by no means the only fragrances that provoke allergic reactions — the EU Commission would reportedly like to restrict the use of another 56 fragrance chemicals. This is the subject of ongoing disputes with the fragrance industry, writes Grenville.
Do some of these compounds look familiar to you? Linalool and limonene are particularly ubiquitous in skincare products — a 2017 Danish study found these ingredients in almost half of the cosmetics surveyed. Here’s how manufacturers sometimes disclose potential allergens:
Even in the EU, not all manufacturers are following the rules. The Danish study found that about 6 per cent of products that labelled the required allergens didn’t list “fragrance/perfume/aroma” on the ingredient list, which is misleading and doesn’t comply with regulations [6]. In the US, dermatologists have also reported in the Journal of Allergy and Clinical Immunology that products described as “hypoallergenic/fragrance free” (admittedly unregulated marketing terms) overwhelmingly contain at least one contain allergen, often fragrance.
Natural vs. synthetic
So we’ve established that fragrance poses a huge risk of provoking allergic dermatitis — but what about the question of natural versus synthetic fragrances?
As you may have spotted, the natural extracts oak moss and treemoss feature in the list of 26 allergenic fragrances restricted by the European Commission. It’s believed that two chemical compounds in oak moss, atranol and chloroatranol, cause at last 20 per cent of fragrance contact allergies. It’s such a concern in industry that classic perfumes are being re-engineered to replace this ingredient.
Many of the restricted allergenic chemicals occur naturally, and in significant concentrations, in essential oils. Lavender extract, for instance, contains between 20–40 per cent of the allergenic fragrance chemical linalool. Skincare forums are abuzz with consumers complaining of skin irritation from products fragranced with lavender. Some studies report that 2 per cent of the population develops eczema-like rashes from contact with lavender (I certainly do), while others put the estimate as high as 7 per cent.
One study named 28 essential oils as established contact allergens, as they naturally contain high concentrations of allergenic fragrance chemicals [3]. The essential oils include ylang-ylang, various citrus peel oils (such as bergamot, mandarin and lemon), eucalyptus leaf, jasmine, lavender, mint and rose. Citrus oils are some of the most phototoxic among fragrances, which means they may provoke an allergic reaction under UV light or increase your sun sensitivity [7].
It doesn’t matter where fragrance chemicals originate from. Natural or synthetic, they are equally irritating. “In terms of toxicity there’s pretty much no difference between synthetic and natural fragrances,” says Ian Musgrave, a molecular toxicologist at the University of Adelaide, interviewed in the Sydney Morning Herald in 2018.
“Limonene, the lovely lemon fragrance from lemons, is also a very good skin sensitiser and allergen, it’s just much easier to make it synthetically than it is to extract thousands and thousands and thousands of lemons.”
And yet, the belief that natural fragrances are less irritating than synthetics still persists.
Dermatitis in droves: are natural ingredients to blame?
Essential oils are big business. Due in part to the cosmetics market, global revenue from essential oils totals into the billions. The natural skin care market grew by 23 per cent from 2017–2018, and accounts for about one quarter of annual skincare sales in the USA. Unfortunately, its popularity is driving up incidences of allergenic reactions.
In September 2019, two dermatologists published an editorial titled “Natural does not mean safe — the dirt on clean beauty products” in JAMA Dermatology. “There seems to be a discordance between what dermatologists know about the science of the skin and what is being disseminated to consumers through the clean beauty movement,” the authors write [8].
Amongst other concerns about “clean beauty”, the authors stated that “many so-called natural products contain high concentrations of botanical extracts that are a leading cause of both irritant and allergic contact dermatitis and photosensitization”. A whole host of (predominantly fragrant) plant extracts can cause skin irritation and contact dermatitis.
Many dermatologists lament the fact that the sector is preoccupied with avoiding propylene glycol, sulphates, parabens et al. (extensive reviews have found these cosmetic ingredients to be nontoxic and noncarcinogenic [9]). At the same time, clean beauty advocates the use of natural extracts that have very high risks of provoking contact dermatitis. A consultant dermatologist for the Mail on Sunday recently described seeing hundreds of women in the UK falling victim to dermatitis from natural skincare products, with essential oils and natural fragrances being key culprits.
Dr Emma Wedgeworth of the British Skin Foundation summed it up: “Pretty much every dermatologist would say the same — that natural skincare is causing serious irritation to people’s skin.”
Many dermatologists are appealing to the FDA to regulate the terms “clean” and “natural” to prevent consumer misconceptions. Make no mistake — clean and natural doesn’t mean safe. While myths about natural fragrances abound, consumers are risking their skin health — while the clean beauty sector profits from their confusion.
References
1. Babu, K.G.D., et al., Essential oil composition of Damask rose (Rosa damascena Mill.) distilled under different pressures and temperatures. Flavour and Fragrance Journal, 2002. 17(2): p. 136–140.
2. Klaschka, U., Naturally toxic: natural substances used in personal care products. Environmental Sciences Europe, 2015. 27(1): p. 1.
3. Uter, W., et al., Categorization of fragrance contact allergens for prioritization of preventive measures: clinical and experimental data and consideration of structure-activity relationships. Contact Dermatitis, 2013. 69(4): p. 196–230.
4. Peiser, M., et al., Allergic contact dermatitis: epidemiology, molecular mechanisms, in vitro methods and regulatory aspects. Cellular and Molecular Life Sciences, 2012. 69(5): p. 763–781.
5. Nematollahi, N., S.D. Kolev, and A. Steinemann, Volatile chemical emissions from essential oils. Air Quality, Atmosphere & Health, 2018. 11(8): p. 949–954.
6. Bennike, N.H., et al., Fragrance contact allergens in 5588 cosmetic products identified through a novel smartphone application. Journal of the European Academy of Dermatology and Venereology, 2018. 32(1): p. 79–85.
7. Placzek, M., et al., Evaluation of phototoxic properties of fragrances. Acta dermato-venereologica, 2007. 87(4): p. 312–6.
8. Rubin, C.B. and B. Brod, Natural Does Not Mean Safe — The Dirt on Clean Beauty Products. JAMA Dermatology, 2019. 155(12): p. 1344–1345.
9. Boyer, I.J., et al., The Cosmetic Ingredient Review Program — Expert Safety Assessments of Cosmetic Ingredients in an Open Forum. International Journal of Toxicology, 2017. 36(5_suppl2): p. 5S-13S.
