 Is a warning justified – about linalool, for example?
When is a warning justified and when is it not? Why has linalool come under suspicion and what lies behind the warnings about linalool?
- Warnings issued since 2009 about linalool’s potential as an allergen were provoked by a Swedish study. When a scientific study makes an educational contribution, it is always an advantage. However, reports on studies are often misleading for a number of reasons.
1. The results are extremely abridged and thus falsely portrayed.
2. The study’s results are portrayed in an unjustifiable context. Reports on the results of the Swedish study commonly feature information such as the fact that linalool is an ingredient in nearly all essential oils. This is correct: linalool is found in lavender oil, orange extract, and many other natural ingredients.
- However, the Swedish study dealt with neither lavender oil nor botanical extracts. It did not even discuss linalool, but rather the consequences of the reaction of linalool with oxygen. The Swedish linalool study from the University of Gothenburg is a perfect example of why abbreviated presentations falsely portray study results.
Why it is not good that it smells good everywhere
Air-conditioning systems transport perfumes in shopping malls and even in hospitals. The industry has pushed the sales of air fresheners for cars and of fragrance-emitting products for bathrooms, living rooms, textiles, etc. Synthetic perfumes, in particular, are omnipresent. These all-pervading fragrances have caught the attention of scientists.
- In order to reach an objective conclusion on the subject of perfume allergies, many scientists understandably maintain that perfumes exposed to air must also be investigated. It is frequently the case that it is not the perfumes themselves, but rather the oxidation products created on their contact with air, that trigger an allergy.
- With regard to linalool, researchers from the University of Gothenburg investigated how people react to oxidized linalool. The result: it is suspected that 2% of Swedes react allergically to oxidized linalool. The fragrance linalool is widely used, especially in detergents and cleaning agents. According to the University of Gothenburg, linalool is found in 60–80% of all scented cleaning products. According to the researchers, it is possible that the use of large quantities is a reason that 2% of Swedes perhaps react to it.
- Manufacturers of cleaning and cosmetic products incorporate substances into their products that prevent the oxidation process for sensitive substances such as linalool. However, allergenic decomposition products can still form during storage. The Gothenburg scientists advise that closing bottles and tubes with the caps and lids they were supplied with instead of leaving them open can prevent the formation of oxidized linalool.
What conclusions can be drawn from the Swedish linalool study?
The Swedish study confirms that oxidation processes resulting from airborne perfumes can be allergenic. It also confirms concerns about “bombarding” people with fragrances. It serves as a further indication that the mass use of fragrances can lead to an increased sensitization rate.
- The study makes no reference either to linalool as an ingredient in natural fragrances such as lavender oil, orange or myrrh extract, or to the use of such natural substances in lotions or other cosmetic products.
- The fact that oxidized fragrances can cause problems is well known. For example, any competent manufacturer of natural and organic cosmetics knows that essential oils must be stored properly in order to prevent oxidation processes.
- The most important reference guide for the safe use of fragrances is the so-called peroxide value. It must be low. This is exactly the criterion that is respected in the responsible production of natural and organic cosmetics. Correct raw-materials handling is just as much a part of a natural and organic cosmetics manufacturer’s key responsibilities as quality assurance with regard to potential raw-materials contamination.
- There can be many causes behind potential contamination. To determine the cause of potential contamination, professional companies have specialist departments that deal with exactly this issue. They ensure that raw materials are examined before use to ensure they are clean.
Studies show: essential oils are better tolerated
 Warnings about allergen risks commonly cause an incorrect impression: no-one would dream of stopping eating nuts because one of their neighbors is allergic to them.
- In other words: whether one of the substances listed above is tolerated or not depends on the individual. People who have no problem with thyme, rosemary, cinnamon, or citric oil will not become allergic through normal contact with these substances.
- The fact that certain substances are classified allergenic to some extent is a precautionary measure. Such categorizations occur when, for example, it becomes apparent that the number of people who react to a certain substance increases, e.g. from 1% to 2%, 4%, or an even higher percentage. Conversely, this also means that 98% or 96% of people have no problem with the substance whatsoever. Cosmetics manufacturers should heed such findings and either forgo the use of certain substances altogether or use them in exceedingly low quantities.
Not all geraniols are the same
When evaluating allergen risks, it must also be taken into account that one INCI designation can stand for completely different substances.
- What a cosmetics manufacturer used – an isolated synthetic substance, a natural essential oil, or a resulting isolated individual component – cannot be determined from the INCI declaration. Synthetic single substances have the same INCI name as substances that are part of a complete essential oil.
- In many cosmetic products, for example, the INCI name geraniol is included in the list of ingredients, but not all geraniols are the same. For people with allergies, the difference can be extremely important; there are clear indications that natural essential oils should be rated differently than synthetic fragrances.
- The German federation of German industry and trade, BDIH, commissioned a study on geraniol. 50 people who reacted sensitively to geraniol in an allergy test were examined to see how they reacted to essential oils with geraniol.
- 20% of people tested reacted to the chemically isolated perfume geraniol, i.e., 10 out of 50.
- None of the 50 subjects reacted to essential oils containing geraniol.
- Because the subject of perfume allergies is highly important in both anthroposophical medicine and natural cosmetics, the company Wala (Dr. Hauschka) commissioned a university skin clinic to conduct a study on natural fragrances. For the clinic test, 25 people with an existing contact allergy to the standard perfume combination were tested. According to the experimental methodology, of the total of 500 individual tests with Dr. Hauschka oils, 500 reactions could have occurred. A high number would have indeed been probable since it had been verified that all subjects were allergic to perfumes.
- Reactions only occurred in 17 of the 500 individual tests.
- Not a single subject reacted to the 0.5% concentration.
- The 17 allergic contact reactions occurred exclusively in the extremely high 5% concentration.
Essential oils are generally used in cosmetic products on a scale from 0.5% to 1%. A dosage over 5% is far beyond any normal occurrence.
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