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Oct 19, 2012
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Over and over again I see on this forum, regardless of the mode of application, most insist that 1.5% is the therapeutic and 3.0% is the maximum safe limit of essential oil usage. I have doubts about the scientific basis behind this since essential oils are composed of hundreds of different chemicals and each chemical has a different toxicity level, and even taking the synergistic effects into consideration, it does not make sense to apply a “one-size-fit-all” approach.

I went along with the general consensus. I was also willing to agree to disagree but it appeared that the sentiment was not reciprocated.

You do know that all three of those can cause early labour in pregnant women and have been used to create abortions right? None of them are safe to use during pregnancy. It is one of the reasons I so strongly recommend knowing your oils. The good news is that most people, including aromatherapists can't afford those oils.

I am simply asking that you know what you are doing. We consider soapmaking a hobby when it is actually chemistry and that includes what we add to the soap. There is nothing wrong with using EO's in your products as long as you are willing to learn EO safety. Of course people will & can do what they want even though they've had what the safe levels are....
Taking that recommendation at heart, I spent the last few days digging up my old organic chemistry, toxicology, and human physiology text books, searched papers related to essential oils and chemicals in essential oils, and talked to the toxicologists I work with.

It is common belief that rose, jasmine, and sandalwood oils may induce abortion, and I have seen these three and a number of other essential oils in aromatherapy books under “avoid using during pregnancy”. There is, however, not a single reported case that inhalation or topical application of essential oils has such effect.1 Even pennyroyal oil (which is reputed to be abortifacient), ingested orally, does not “effectively” induce abortion. It causes severe liver damage or death and if the woman does miscarry, it is due to more of the fact that she is dying.2,3 After an extensive search on PubMed, I failed to find any documented cases of essential oil induced abortion. I also referenced Chinese herbal medicine and found no contraindication of using rose, jasmine, and sandalwood in any form on pregnant women.

Martin Watt even went further to say that:

“I have chosen Pennyroyal as my subject as it is a classic example of incorrect information LEADING TO DEATHS AND SEVERE ILLNESS. Some Herbalists, most Aromatherapy organisations and authors (actively supported by science professionals), have been very active in promoting myths about the dangers of these plants and their oils. If it were not for them, then the incidence of women who have poisoned themselves in vain attempts to procure abortions would have been substantially lower”.4

Similar sentiments are shared by Ron Guba:

“In the wide variety of Aromatherapy books and periodicals available today, we find many recommendations regarding the safe, therapeutic use of essential oils, often contradictory and seldom supported by either references, research or actual clinical experience”.5

In another post I mentioned that lavender oil is quite “safe” and can be used at 5% in soap. I was corrected, and told that since the therapeutic level is 1.5%, 3% is the limit even given the fact that some of the chemical compounds are altered during the course of making cold processed soap, some of the more volatile compounds are driven off by the heat, and further degradation is highly likely during the exposure to air and UV light during curing.

Lavender oil consists of 25% to 50% of linalool and 25% to 30% of linalyl acetate. (The exact percentage varies due to the plants used, soil and climatic conditions, etc). During saponification, linalyl acetate reacts with NaOH and one of the products is linalool.6 Therefore the most abundant chemical in lavender oil (added to cold processed soap) is linalool.

In a human health assessment conducted by the US Environmental Protection Agency, the NOEL (no observable effect level) for dermal toxicity was found to be greater than 250mg per kg of body weight over a course 90 days.7 In other words, in order to have an observable effect on a 50kg woman, she would have to be exposed to more than 12.5g of linalool, or approximately 15g of lavender oil, everyday for 90 days. The NOEL of 250mg/kg is based on prolong contact with lavender oil (i.e. smear oneself with 15g lavender oil and leave it on for hours).

In order to take into account that soap is a wash-off product, I am referring to studies done by Research Institute of Fragrance Materials (RIFM).8 In their calculations to estimate dermal exposure to chemicals from cosmetic products, they assign a “retention factor” for different products. For example, body lotion has a factor of 1.000, and shower gel and soap have a factor of 0.010. Intuitively it makes sense as one applies body lotion to a large portion of the skin and it stays on, whereas shower gel and soap only come in brief contact with the skin. It is then possible to extrapolate that if it is safe to use 1.5% essential oil in a full body massage, then it is safe to use 1.5% ÷ 0.010 = 150% essential oil in soap. Obviously common sense dictates that it is impractical and impossible to do so, but it just goes to illustrate that for cold processed soap, it is safe to use lavender oil at higher than 3% or 5%.

Having said that, there are limited evidence that lavender oil (and tea tree oil) might be considered as endocrine disruptors.9 The results are, however, inconclusive, neither the original researchers nor the Centers for Disease Control and Prevention (CDC) have issued any warnings.10

From an empirical standpoint, there are established, reputable soap makers, such as the Soap Queen, Nova Studio, Soap Making Essentials, and Soap Making Resources that either have recipes which call for, or have calculators that recommend one to use 5% (or higher) essential oils in making cold processed soap. We have not seen any reported cases of injury from these soap makers or people following their suggestions.

In addition, some widely used over the counter products contain very high percentage of essential oils. Tiger Balm contains 6% to 16% de-mentholized mint oil (menthol was added back at a rate of 10% of some versions of the product), 7% to 13% cajuput oil, 1.5% to 5% clove oil, and a few others. Vicks Vapor Rub contains essential oils and chemicals commonly found in essential oils. Both products have been used for a long time (in the case of Tiger Balm, over 100 years) in many different countries and there has not been any documented case of essential oil overdose from topical application.

There has been one reported case of methyl salicylate death from topical application of BenGay (15% to 30% methyl salicylate), but the victim was also using two other products that contain methyl salicylate at the same time. There were a few cases of non-lethal overdose when patients were not following the recommended usage.11 Consider the fact that BenGay (or Bengué, the originally name, after the French doctor who developed it back in 1898) has been around for a long time, less than half a dozen reported cases of BenGay or related products overdose should not be a reflection that the product is poorly formulated. To put things in perspective, each year there are over 50 cases of acetaminophen (available over the counter as Tylenol or Excedrin) overdose that led to acute liver failure in the US alone.12

I want to emphasize that I am not challenging the idea that the therapeutic level of essential oils is 1.5% as I have not done enough research on that. I am, however, having severe doubts that simply because the therapeutic level is 1.5%, it is unsafe to use more than 3% regardless of the mode of application and the type of oil used. Not only does the mode of application make a huge difference in absorption rate (as stated in several papers quoted earlier), different chemicals have different therapeutic ratios – the ratio between toxic dose and effective dose.

For example, based on a 1991 United Kingdom guideline, the recommended dosage of Vitamin A for an adult male (over 15 years of age) is 700µg per day. Chronic toxicity is observed when an adult male consumes 10mg per day for a month; and acute toxicity at 200mg. So loosely speaking the therapeutic dose is 700µg, and the toxic dose is 10mg.

The United Kingdom's recommended dosage for Vitamin C is 40mg per day. People have known to take 1 to 10g per day with no toxic effects.

Therefore the therapeutic ratio for Vitamin A is:

10mg ÷ 700µg ?14.29

And the therapeutic ratio of Vitamin C is:

10g ÷ 40mg = 250

Even though both vitamin A and vitamin C are commonly called vitamins, they are completely different chemicals. One has a therapeutic ratio of 14.29, the other has a therapeutic ratio of 250. How can it be logical to claim that all essential oils, which contain different chemicals, have the same therapeutic ratio of 2 (3% ÷ 1.5% = 2)?

There also leaves a lot of uncertainty when the therapeutic (or toxic) level is expressed in percentage with no reference to the actual quantity. i.e. 1.5% is the therapeutic level. Is it 1.5% of 1g (which would be 15mg of essential oil), or 1.5% of 100kg (which would be 1.5kg of essential oil)? I can safely ingest 15mg of wintergreen oil, as the amount of salicylic acid (from methyl salicylate, the main component of wintergreen oil) is 5 times less than a baby aspirin, which contains 81mg of salicylic acid. 1.5kg of wintergreen oil, on the other hand, is probably enough to kill an elephant!

This brings up the fact that some essential oils, or chemicals found in essential oils, are routinely used in food products. Chewing gums, candies, root beer, etc. used to contain a minute amount of wintergreen oil. Nowadays it is more common and cost-effective to manufacturer methyl salicylate from synthetic process than to extract it from plants. For the same reason, fragrance oils are made up with a large portion of the identical chemicals composed of the plant essential oils being imitated. For example, the main components of lavender fragrance oil are linalool, linalyl acetate, eucalyptol, camphor, etc. It is illogical to consider it unsafe to use more than 3% essential oil yet it is fine to use 5% fragrance oil, or whatever the manufacturer’s recommended rates are, when in many instances the chemical composition of both oils are almost identical.

Up until last week, I accepted the “expert” opinion on this forum and the “3% rule”. Last week I was also told to “know what I am doing”, which is why I re-read text books, looked up papers, and talked to people who know what they are doing. The conclusion is now I will not accept the arbitrary 3% rate of safe essential oil usage, not in cold processed soap anyway. Obviously there are no reasons to use more than the minimal amount to achieve the desired results – be it for scents or therapy – but that minimal amount should be determined by many factors and not necessarily at 3%.

I realized that I failed to address the toxicity level from inhalation. There are simply too many variables in the equation to do so. I have a crazy day job and limited time to read papers on essential oil toxicity. I also did not address sensitivities and allergies for the same reason.

I am thankful to Lindy for the motivation to basically conduct a risk assessment (albeit brief and incomplete) on my own. It makes me more comfortable in what I am doing.

1. ... es&f=false
3. ... 46je10.htm
6. ... evin-dunn/
7. ... Jun-08.pdf
8. ... 122007.pdf

*The opinions in this are solely those of Seifenblasen and not in anyway endorsed by Soap Making Forum. In fact, they go strongly against this forum's guidelines for safe usage of essential oils.

Edited to correct typing mistakes and to clean up the formatting for easier reading. Further edited to include CYA statement.
Thank you so much for sharing some scientifically based information on Essential Oils and their safe usage. It can be very hard to find accurate information on the Internet, or even in books regarding their use in soap. I appreciate all the effort you put in to your post. Even though I have used and studied essential oils for over 12 years, I still learned some new information and intend to study it further. Great resources in the footnotes!
I am a relative novice when it comes to essential oils compared to some members of this forum. I found this post to be well reasoned and appreciate the time and research that went into it.
I too appreciate the amount of work it took for you to come up with this information. There is always room to grow and to learn. The book that is my preferred scientific reference is Aromatherapy for the Health Professional.

The reason the "accepted" expert aromatherapist opinions are what they are in aromatherapy is to protect those most prone. As I stated before people with autoimmune illnesses, alcoholics, seniors, babies and others with varying illness can only tolerate safely 1.5% levels of essential oils. So when you are being told that at 1.5% essential oils become therapeutic and at 3% they are fully therapeutic we are trying to protect the most vulnerable of our society. Not all essential oils are equal and each one affects different parts of the body so usage levels are actually different but I don't think this is the place to list every, single essential oils at what the appropriate percentage for each part of the population down to illness, age, etc., etc., I'm sure you can see why this is inappropriate because the amount of information would overwhelm the average user.

The people you have mentioned as being soapmakers recommending 5% for soap (Soap Queen, Nova Studio, Soap Making Essentials, and Soap Making Resources) are soap suppliers, not aromatherapists.

As I stated in my post that you quoted you can do as you like now I will add that I don't feel you are qualified to guide others in the amounts to be used safely. Can you tell me for instance what the contraindicators are for Rosemary? Do you know for a fact what the rate of absorption is for every single essential oil? Does not the superfatting oils remain on the skin after rinsing? Wouldn't this amount be different with each individual as well as each different soap? How much of the essential oil transfers and remains in the superfat oils? These are the reasons that responsible aromatherapists give you such low percentages. It is not fear mongering although I personally have a cousin that died from Wintergreen.

At any rate, I find it very sad that you find it so important to be right, however you need to do what you feel is right. I also would like to address you comment about being banned for disagreeing with information I shared with you. Last time I checked we don't ban you for disagreeing, at least not the current moderators and administrators. Banning occurs for other reasons, but not this.

Again I would like to thank you for taking the time to show how right you are, there is truly some good information there.

Can you tell me for instance what the contraindicators are for Rosemary?

I can tell you at least one out of three of those is bogus - pregnancy. :twisted:

As I stated in my post that you quoted you can do as you like now I will add that I don't feel you are qualified to guide others in the amounts to be used safely.

At any rate, I find it very sad that you find it so important to be right, however you need to do what you feel is right.

Unfortunately, this is exactly how I think of you now. It is not enough that I agreed to disagree and adopted your 3%. It is not enough that I edited my replies to the originally poster. It is not enough that I went back and put disclaimer on every one of my soap recipe shared. It is not enough that I, however grudgingly, admitted on this forum that you are right.

I don't need to be right. I simply refuse to accept "facts" without any scientific basis.

I never wrote this with the intention to provide others guidance on aromatherapy. I wrote this to show others that what is important is not the ability to memorize an "essential oil phone book", but the ability to do deductive reasoning, and never stop thinking for oneself.
I appreciate all the work and links that you provided us with. A lot of good information there. I understand how you feel with the frustration of the 3% "rule". I've studied eo's and aromatherapy and I've learned that it is possible to use more than 5% of some eo's safely without any problems on someone with no underlying conditions.
Personally I never recommend eo's for a pregnant or nursing woman without them talking to their doctor. Why? Because there's not enough research and studies done on eo's and pregnant women, plus with pregnancies you have so many things to factor in that in my opinion the possible risks do not outweigh the benefit of the eo's. I for one do not feel confident enough in my experiences with eo's & aromatherapy to take that risk.

As for why this forum sticks to the 3% or less rule on eo's is very simple. Lawsuits. People come here, take the information and a lot of times do not do their own research. We do not want to be held liable for someone hurting someone because of their laziness to do further research.
Seifenblasen said:
...the ability to do deductive reasoning, and never stop thinking for oneself.
Everyone should apply this to everything in their life (how generalized was that?!)...this is how humankind has progressed.
Genny said:
As for why this forum sticks to the 3% or less rule on eo's is very simple. Lawsuits. People come here, take the information and a lot of times do not do their own research. We do not want to be held liable for someone hurting someone because of their laziness to do further research.
I assumed this was the reasoning behind this. C.Y.A.(Glad to have it confirmed). Its too bad that this always has to be a well as people not reading labels and using something they are allergic to, and then wanting to hold the manufacturer liable :evil: (which is my reasoning behind my strong stance of "truth in labeling" whether the FDA requires it or not)
As for why this forum sticks to the 3% or less rule on eo's is very simple. Lawsuits. People come here, take the information and a lot of times do not do their own research. We do not want to be held liable for someone hurting someone because of their laziness to do further research.

Thank you very much (finally) for a straight forward, honest answer! I rest my case. :D

Also added a CYA statement to my original post to protect the innocent.
Seifenblasen at this point I think there is nothing more to be gained by this conversation. You seem to feel the need to be vindicated publicly which is truly sad. What I am going to suggest is that you not try to set yourself up as an "expert" when talking about percentages of essential oils because this is a teaching forum and there are far too many newbies who see anything written in here as gospel. The CYA is because essential oils are therapeutic, but you can view it any way you want.

So I am going to close this thread down. You have made your point that you are smarter than any aromatherapist out there because, well, you are.

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