This article was created for the website Professional societies of Czech aromatherapy.
Pressed citrus oils, with their explosion of refreshing aromas and therapeutic properties, invite incorporation not only into aromatherapy mixtures, but also into cosmetics and perfumes. Unfortunately, thanks to their natural components, furocoumarins (FCs), they cause irritation, the so-called phototoxic reaction, after exposing the skin to the sun and UV lamps (up to 18 hours after application!). Manifested by phototoxic dermatitis, the signs of which are pain, redness, blisters and pigmentation.
Phototoxic reaction and IFRA intervention
How and why does it occur? FCs molecules can bind to the DNA of skin cells when we expose the skin to UV radiation. This causes their cell death, which we notice with the aforementioned unpleasant reaction. Thanks to the intervention of IFRA (International Fragrance Association), there was a legislative restriction on the use of citrus oils in cosmetics and perfumes. And this was also one of the main reasons why distilled citrus essential oils began to be produced, which do not contain FCs at all or their content is negligible.
What are furocoumarins or furanocoumarins (FCs)?
Furocoumarins are natural components of essential oils pressed from the peel of citrus fruits. Perhaps the best known of them is bergapten in bergamot oil and citropten in lemon, bergamot and lime oil. However, FCs are also found in other essential oils than just citrus ones, e.g. angelicine at the Angelica of the doctor, methoxsalen at the fragrant Rue, psoralen for bergamot, valerian, angelica and bitter orange oils, marmesin a 8-hydroxybergapten at Morača zákrónatéhy.
Margarite dermatitis and other peculiarities
A special feature are the phototoxic components, which do not belong to the furocoumarins, but it is still worth mentioning them. These are alpha-Terthienyl with marigold oil, dimethyl anthranilate for mandarin leaf oil, because even with these essential oils, we should adhere to dermal limits when applying them to the skin. Another interesting fact is hypericin, which is represented in the beautiful red macerate of St. John's wort flowers and causes a phototoxic reaction only after internal use, this heavy molecule is not present in the essential oil (R. Tisserand, Essential Oil Safety, 2nd edition, p. 417). I cannot forget the well-known plants that can cause irritation due to their FCs content. Be careful when handling celery, parsley, hogweed. Or the notorious beach “margarita dermatitis”, when squeezing limes and lemons releases FCs from the peel into the juice and thus onto the surface of our hands. When we add sunlight, which cannot be avoided when staying at the beach, a phototoxic reaction occurs. See the photos on the website for its consequences Tisserand Institute.
Furocoumarin transfer
Furocoumarins are present in these essential oils in a small percentage of about 1-2%, but even 0,1% can be phototoxic. FCs molecules are non-volatile, heavy and therefore larger than most other molecules of essential oil components. R. Tisserand mentions that it is very likely that the heavier FCs molecules will also be transferred to Co2 extracts and absolutes (R. Tisserand, Essential Oil Safety, 2nd edition, p. 87). That is why he lists not only marigold essential oil as phototoxic, but also its absolute. And the same goes for fig leaf absolute.
Distilled citrus oils
Phototoxic reactions to perfumes containing bergamot oil were first reported in 1916. Over the years, scientists have drawn attention to the link between FCs and UV radiation. Thanks to the work of IFRA and their publication of safety recommendations for citrus oils, this has been a rare occurrence since the 1970s. All these aspects led to the industrial production of distilled citrus oils. They have a milder aroma and are completely colorless. Pressed ones are colored and have a richer aroma, but also due to FCs, dermal limits when applied to the skin. R. Tisserand points out that distilled citrus oils are safe and non-phototoxic (R. Tisserand, Essential Oil Safety, 2nd edition, p. 87), mainly due to the fact that the non-volatile heavier molecules of FCs do not pass into the essential oil during the distillation process! And therefore these essential oils contain practically no FCs and are not as phototoxic (R. Tisserand: Phototoxicity: essential oils, sun and safety, 20.6.2023)
R. Tisserand includes the so-called safe non-phototoxic citrus fruits::
Distilled EO: Bergamot, Grapefruit, Lemon, Lime, Mandarin, Orange
Pressed EO: Sweet or blood orange
Other notes: Lemon leaf, Neroli, Petitgrain
R. Tisserand includes the following as probably slightly phototoxic:
Tangerine, Mandarin (fruit), Parsley, Ginger, Yuzu, Patchouli
Distilled versus pressed
Science continues to inform us about how and why distilled citrus is safe. The evidence is, for example, HPLC (High-performance liquid chromatography) analysis of distilled lemon oil. Its results show that it contains 12 times less isopimpinelline, 22 times less bergapten and 930 times less citropten than pressed lemon oil, which means that distilled lemon oil is not phototoxic, even though it contains some FCs.
Terrifying consequences
On the other hand, I recommend looking into the database to find out what can be caused by the unprofessional use of pressed lime oil as part of a homemade deodorant in coconut oil. Adverse Reaction at the Tisserand Institute. Or the really very clumsy use of undiluted bergamot pressed oil before entering the steam sauna followed by the solarium with its terrifying consequences. I warn you that it is really unsightly sight.
Professionalism above all
Finally, it should be noted that the dermal limits according to IFRA 50 and 51 for pressed citrus oils apply “only” to cosmetics and perfumery. I personally recommend that professional aromatherapists also pay attention to their updated form as part of a professional approach to the client’s health. You can also find practical tables in the second edition of Tisserand & Young (2014) – Essential Oil Safety. If you are interested in distilled citrus oils or prefer them in your practice, I recommend a diverse product line distilled citrus oils family company SoZoLe RoseYou will also find here pressed citrus oils from smaller batches of Italian growers and distilleries. This gives you the opportunity to easily compare individual types and choose exactly according to your needs.
Sources:
Tisserand & Young (2014). Essential Oil Safety 2e. Churchill Livingstone, Edinburgh.
R. Tisserand: Phototoxicity: essential oils, sun and safety (20.6.2023) https://tisserandinstitute.org/phototoxicity-essential-oils-sun-and-safety/
Li, G., Xiang, S., Pan, Y. et al (2021). Effects of cold-pressing and hydrodistillation on the active non-volatile components in lemon essential oil and the effects of the resulting oils on aging-related oxidative stress in mice. Frontiers in Nutrition, 8(June), 1–15.
https://doi.org/10.3389/fnut.2021.689094
Adverse Reaction Report Details – lime expressed oil https://tisserandinstitute.org/adverse-reaction-database/#home/adverse-reaction-report-detailed-view/5909ab1aac4d112661576d4e/
Adverse Reaction Report Details – bergamot expressed oil https://tisserandinstitute.org/adverse-reaction-database/#home/adverse-reaction-report-detailed-view/5909a23d6000582668659041/
Index of IFRA Standards - 51st Amendment
IFRA Standards
https://ifrafragrance.org/safe-use/standards-documentation
IFRA Complete Standards 50th
