Are Essential Oils Safe? Part 2

are-eos-safe-2aThoughts on Essential Oil Authenticity, Adulteration, Safety and Ethics: Part 2

In my first article on the use and safety of essential oils, I went over the difference between synthetic fragrances and essential oils, external uses of oils, some general cautions about adulteration and some suggestions for purchasing high quality oils. In this follow up article, I will discuss common dilutions, carrier oils, essential oil adulteration, testing for impurities and the best practices to keep your essential oils fresh.

Common Dilutions

When we think about diluting essential oils by the drop, we need to think about their viscosity, or how thick the oil is. Thicker oils, like resins, make larger drops and thinner oils make smaller drops. That is one reason we have dosage ranges when we talk about dilutions. Here are some basic dilutions:

  • On average, 1 milliliter of essential oils = 30-40 drops.
  • 1%: 5-6 drops per ounce. This is a good dilution for children, pregnant women, elders, those who tend to be sensitive and for face care.
  • 2%: 10-12 drops per ounce. This is the most common dilution and is good for most applications.
  • 3%: 15-18 drops per ounce. Good dilutions for treating small, target areas of the body.
  • 7-10 %: 35-60 drops per ounce of carrier oil. This dilution can be used for perfumes and specific treatments such as toenail fungus and warts.

Carrier Oils

Also called fixed oils, carrier oils are typically natural, non-volatile oils derived from fruits, vegetables, nuts and seeds. They help moisturize, lubricate and protect the skin. Whenever possible, use cold pressed, unrefined oils as they are more nourishing to the skin. Some of my favorite carrier oils are hazelnut, almond, apricot kernel, macadamia nut, olive and sesame. If I am using a precious essential oil (think rare and expensive), I like to use jojoba oil. Jojoba oil has an especially long shelf life. One of my favorite oils for the skin, it is chemically very similar to sebum, the oil our skin produces. I recommend staying away from oils that are petroleum based such as mineral oil.


Like a fine wine, each harvest of plants is unique. That is one of the beautiful things about essential oils. It is also one of the things that make them hard to work with if you are a big business and want a consistent smell/product year after year. I prefer artisanal products. Is there a particular reason your lotion or perfume needs to smell exactly the same each batch? In nature, things are always changing. Instead, lets have an adventure every time!

You Get What You Pay For

It is absolutely true that cost often reflects quality and authenticity of essential oils. For instance, pure rose otto steam distilled essential oil that is sold for less than $150 for a dram (3.75 milliliters) is most probably adulterated and of questionable quality.



If we are using essential oils for a healing, or therapeutic purpose, quality is very important. Most essential oils have between 20 – 50 easily identifiable chemical markers, some up to 200. As I said in my first article on essential oils, I look for oils that are tested by gas chromatography. Gas chromatography authenticates the chemical composition of an essential oil, like a “fingerprint” unique to that botanical species only.


Unfortunately, in the United States, purchasing high quality oils can be a risky process. There are several forms of adulteration.

  1. “Natural” Adulteration: Essential oils can be blended with other less expensive essential oils to achieve a similar smell. An example of this would be adding a less expensive camphor essential oil to extend rosemary essential oil, which costs more.
  2. Companies also add less expensive constituents that naturally occur in oil by getting it from other plant material. An example of this would be adding geraniol from Geranium to extend Rose essential oil.
  3. Some manufacturers or end companies will add cheap, synthetic, similar-smelling substances to their oils, purely for profit. These synthetic fragrances have no therapeutic value, rather, I think of them as taking away from the healing process.
  4. Adulteration can also happen by adding extenders such as alcohol, fixed oils and odorless solvents.

Testing for Impurities

How do we know if an essential oil is pure? The honest truth is that sometimes we don’t. But there are some simple home tests that can help suss out most adulterants!

  1. Vegetable oil is the most common adulterant. Vegetable oils have a greasy feel between the fingers and unlike most essential oils they do not evaporate completely. Try the paper test. Drop one drop of each or your essential oils onto a white sheet of paper. Circle it with a pen and write the oil’s name by the circle. Most pure essential oils will evaporate, although some will leave a color behind while some resins leave a faint stain. Essential oils adulterated with a fixed oil will leave an oily stain.
  2. Water test: Essential oils are hydrophobic, meaning they don’t chemically combine with water. All pure oils should never mix with water, and will either float on top, or sink to the bottom. Some adulterated oils will dissolve or turn milky due to emulsifiers or surfactants.
  3. Ethyl alcohol: If essential oil is adulterated with alcohol, it will have a distinctive, alcoholic, smell. I recommend smelling lots of oils to refine your perception. This will help you “catch” an essential oil that doesn’t smell right. If it doesn’t pass the nose test, don’t buy it.

You can test your essential oils to see which ones are adulterated. Use adulterated oils for making soap, potpourri or cleaning supplies.

Proper Storage and Shelf Life

There are several things you can do to prolong the shelf life of your essential oils. Although each type of oil has a unique shelf life, when stored properly, most oils last for many years. As essential oils degrade, their therapeutic properties diminish. Their smell will usually change before the oils become unsuitable for use.


General Guidelines to Keep Oils Fresh

  1. Store essential oils out of direct light in well-sealed, dark glass bottles.
  2. Keep your oils way from heat and temperature changes.
  3. In general, I recommend buying smaller amounts of oils so that they stay fresher.
  4. Storing essential oils in the refrigerator will preserve them longer.
  5. Store your oils in smaller bottles that leave less room for oxygen, which degrades essential oils.
  6. Essential oils from resins, roots, and wood oils generally mature and get better with age. Examples of resins include frankincense, myrrh, sandalwood, patchouli, vetiver and spikenard.
  7. Absolute oils are made by using a chemical solvent such as hexane. These chemical solvents are generally used with plants that produce a lower yield of essential oils. They tend to have a long shelf life of five or more years. Examples of absolutes include jasmine, rose, tuberose, violet, vanilla and oakmoss.
  8. Citrus oils and oils from coniferous trees generally have a shorter shelf life of around 9 to 18 months. Examples of citrus oils include bergamot, lemon, orange and mandarin. Coniferous oils include fir, pine, thuja, juniper and spruce.

Not all essential oils sold on the market today are pure appropriate for therapeutic use. I hope this article offers some useful guidelines to help you make sure your oils are unadulterated, fresh, and used in the safest way possible.

© Elaine Sheff, Clinical Herbalist 2016

ElaineAbout the Author:
The author of several books on herbal medicine and healing, clinical herbalist Elaine Sheff has been passionate about sharing herbal knowledge for over 25 years. Her latest book is Naked: Botanical Recipes for Vibrant Skin and Healthy Hair. Elaine is the Co-Director of Green Path Herb School, located in Missoula, MT, where she strives to inspire and empower students and clients to remember their connection to the earth, the plants and their own healing process. As a certified Instructor of the Natural Family Planning and Fertility Awareness Methods, Elaine has helped many couples to avoid or achieve pregnancy naturally. An artist and writer, Elaine has written numerous articles about her family’s journey with epilepsy and a special needs child. You can often find her bent over an herb in her garden or marveling at small flowers in mountain meadows with her husband and sons.

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One Comment on “Are Essential Oils Safe? Part 2

  1. Thank you so much for the information. I find it very useful and will put into practice your advice. Thank you again.

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