Seifenblasen
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- Oct 19, 2012
- Messages
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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.
viewtopic.php?f=21&t=34284
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.
References
1. http://books.google.com/books?id=nZXMC7 ... es&f=false
2. http://livertox.nih.gov/Pennyroyal.htm
3. http://www.inchem.org/documents/jecfa/j ... 46je10.htm
4. http://www.aromamedical.com/articles/pennyroy.html
5. http://www.naha.org/articles/toxicity_myths.htm
6. http://roberttisserand.com/2011/06/esse ... evin-dunn/
7. http://www.epa.gov/pesticides/chem_sear ... Jun-08.pdf
8. http://rifm.org/doc/Food%20&%20Chem%20T ... 122007.pdf
9. http://www.nih.gov/news/pr/jan2007/niehs-31.htm
10. http://personalcaretruth.com/2010/07/ask-the-experts-7/
11. http://www.athleteinme.com/ArticleView.aspx?id=712
12. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2659888/
*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.
I went along with the general consensus. I was also willing to agree to disagree but it appeared that the sentiment was not reciprocated.
viewtopic.php?f=21&t=34284
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.
References
1. http://books.google.com/books?id=nZXMC7 ... es&f=false
2. http://livertox.nih.gov/Pennyroyal.htm
3. http://www.inchem.org/documents/jecfa/j ... 46je10.htm
4. http://www.aromamedical.com/articles/pennyroy.html
5. http://www.naha.org/articles/toxicity_myths.htm
6. http://roberttisserand.com/2011/06/esse ... evin-dunn/
7. http://www.epa.gov/pesticides/chem_sear ... Jun-08.pdf
8. http://rifm.org/doc/Food%20&%20Chem%20T ... 122007.pdf
9. http://www.nih.gov/news/pr/jan2007/niehs-31.htm
10. http://personalcaretruth.com/2010/07/ask-the-experts-7/
11. http://www.athleteinme.com/ArticleView.aspx?id=712
12. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2659888/
*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.
