We thought it was important to share this from “Essential Oil Safety: A Guide for Health Care Professionals” by Robert Tisserand, Rodney Young –
• A typical essential oil is a complex mixture of some 20–200 organic compounds, the great majority being present at levels of less than 1%. If sufficiently potent, these may still be important either therapeutically or toxicologically.
• Essential oils are moderately volatile and lipid -soluble, and have a very small degree of water solubility.
• Essential oils are either distilled or, in the case of citrus oils, cold-pressed. Other forms of aromatic extract include concretes, absolutes, resinoids and CO2 extracts.
• There is a degree of variation in the concentrations of constituents in essential oils from the same species of plant. This is due to factors such as the plant’s environment and growing conditions, harvesting and distillation techniques, or genetics.
• Plants of the same species that generate essential oils with quite different constituent profiles are called chemotypes. Chemotypes are genetically determined.
• Essential oils are not generally subject to microbial contamination.
• Contaminants such as phthalate esters and biocides may be found in essential oils , and traces of solvents such as cyclohexane may be present in absolutes.
• Essential oils are subject to adulteration, in which either odorous or non-odorous substances are added to increase volume and, therefore, profits.
• Contaminants and adulterants are generally detectable by laboratory analysis, such as GC, MS and NMR spectroscopy.
• Contamination or adulteration may increase toxicity.
• Some essential oils are very sensitive to the effects of light, heat, air and moisture. To avoid degradation, all essential oils should be stored away from direct sunlight in tightly stoppered dark glass bottles in a cool place such as a refrigerator.
•The addition of antioxidants to essential oils prone to oxidation (or preparations containing them) is recommended.
•Degradation can lead to increased hazards. The oxidation of some terpenes, for instance, makes them more likely to cause skin sensitization.
•Most toxic effects of essential oils are attributable to known constituents.
•Each essential oil constituent is composed of one or more functional groups attached to a hydrocarbon skeleton. It is the combined effects of these constituents that lend the oil characteristics such as odor, therapeutic properties and toxicity.
•The types of compound found in essential oils include hydrocarbons, alcohols, phenols, aldehydes, ketones, esters, ethers, peroxides, lactones, carboxylic acids, furans, furanocoumarins and sulfur compounds.
•Phenols are often irritants, aldehydes and sesquiterpene lactones may be skin sensitizers, some ethers are carcinogenic, and some bicyclic, monoterpenoid ketones are neurotoxic.
•Isomers are compounds that have identical numbers and types of constituent atoms, but differ in the ways in which their atoms are arranged in the molecule. Structural isomers differ in the way that their atoms are connected together, while geometric and optical isomers have the same connections between atoms, but different arrangements of atoms in space.
1. It is important, for reasons of clarity, to distinguish between the various types of oils and extracts, and not all of them are referred to as ‘essential oils’. Unfortunately, however, there is no single word to describe the whole family of aromatic extracts, especially since for many people the word ‘extract’connotes a material that is specifically not an essential oil.
2. CO2 extracts are relatively new and little used, and consequently there is little or no toxicological data on them. However, they are used in aromatherapy, as are the even newer ‘phytols’. Both CO2 extracts and phytols (not to be confused with the constituent, phytol) more closely resemble the aromatic material as it occurs in the plant, than do essential oils, but they are both more costly.
3. β-Eudesmol, and various wood essential oils, mitigate the toxic effects of organophosphorus pesticides (Chiou et al 1995; Li et al 2006).
Aldridge, J. E., Meyer, A., Seidler, F. J., et al. Alterations in central nervous system serotonergic and dopaminergic synaptic activity in adulthood after prenatal or neonatal chlorpyrifos exposure. Environ. Health Perspect. 2005; 113: 1027–1031.
Anon, Council directive of 27 July 1976 on the approximation of the laws of the member states relating to cosmetic products. Office for Official Publications of the European Communities, 2003. http://www.obelis. net/ website/ library/ Directives/ files/ cos. pdf Api, A. M. Toxicological profile of diethyl phthalate: a vehicle for fragrance and cosmetic ingredients. Food Chem. Toxicol. 2001; 39: 97–108.
Arctander, S. Perfume and flavor materials of natural origin. New Jersey: Elizabeth; 1960. [Self-published]. Belanger, A. Residues of azinphos-methyl, cypermethrin, benomyl and chlorothalonil in monarda and peppermint oil. Acta Horticulturae. 1989; 249: 67–73.
Belsito, D., Bickers, D., Bruze, M., et al. A toxicologic and dermatologic assessment of cylic and non-cyclic terpene alcohols when used as fragrance ingredients. Food Chem. Toxicol. 2008; 46: S1–S71.
Briggs, C. J., McLaughlin, L. D. Low-temperature thin-layer chromatograph for detection of polybutene contamination in volatile oils. J. Chromatogr. 1974; 101( 2): 403–407.
Burfield, T., The adulteration of essential oils –and the consequences to aromatherapy and natural perfumery practice, 2003. (accessed 05. 08. 12. www. naha. org/ articles/ adulteration_1. htm Candan, F., Unlu, M., Tepe, B., et al. Antioxidant and antimicrobial activity of the essential oil and methanol extracts of Achillea millefolium subsp. millefolium Afan. (Asteraceae). J. Ethnopharmacol. 2003; 87: 215–220.
Chalchat, J. C., Garry, R. P., Michet, A. Variation of the chemical composition of essential oil of Mentha piperita L. during the growing time. Journal of Essential Oil Research. 1997; 9: 463–465.
Chiou, L. C., Ling, J. Y., Chang, C. C. beta-Eudesmol as an antidote for intoxication from organophosphorus anticholinesterase agents. Eur. J. Pharmacol. 1995; 292: 151–156.
Di Bella, G., Saitta, M., Pellegrino, M., et al. Contamination of Italian citrus essential oils: presence of phthalate esters. J. Agric. Food Chem. 1999; 47: 1009–1012.
Di Bella, G., Saitta, M., La Pera, L., et al. Pesticide and plasticizer residues in bergamot essential oils from Calabria (Italy). Chemosphere. 2004; 56: 777–782.
Dikshith, T. S., Kumar, S. N., Tandon, G. S., et al. Pesticide residues in edible oils and oil seeds. Bull. Environ. Contam. Toxicol. 1989; 42: 50–56.
Dugo, G., Saitta, M., Di Bella, G., et al. Organophosphorus and organochlorine pesticide residues in Italian citrus oils. Perfumer & Flavorist. 1997; 22: 33–44.
Duty, S. M., Silva, M. J., Barr, D. B., et al. Phthalate exposure and human semen parameters. Epidemiology. 2003; 14: 269–277.
Forbes, R. J. A short history of the art of distillation. Leiden: E J Brill; 1970. Garland, S. M., Menary, R. C., Davies, N. W. Dissipation of propiconazole and tebuconazole in peppermint crops (Mentha piperita (Labiatae)) and their residues in distilled oils. J. Agric. Food Chem. 1999; 47: 294–298.
Gayathri, N. S., Dhanya, C. R., Indu, A. R., et al. Changes in some hormones by low doses of di (2-ethyl hexyl) phthalate (DEHP), a commonly used plasticizer in PVC blood storage bags and medical tubing. Indian J. Med. Res. 2004; 119: 139–144.
Goetz, A. K., Ren, H., Schmid, J. E., et al. Disruption of testosterone homeostasis as a mode of action for the reproductive toxicity of triazole fungicides in the male rat. Toxicol. Sci. 2007; 95: 227–239.
Gomes Do Espirito Santo, M. E., Marrama, L., Ndiaye, K., et al. Investigation of deaths in an area of groundnut plantations in Casamance, South of Senegal after exposure to Carbofuran, Thiram and Benomyl. J. Expo. Anal. Environ. Epidemiol. 2002; 12: 381–388.
Gopalakrishnan, N. Studies on the storage quality of CO2 extracted cardamom and clove bud oils. J. Agric. Food Chem. 1994; 42: 796–798.
Gupta, A., Myrdal, P. B. Development of a perillyl alcohol topical cream formulation. Int. J. Pharm. 2004; 269: 373–383. Hotchkiss, S. A. How thin is your skin? New Sci. 1994; 141( 1910): 24–27.
IFRA Standards, including amendments as of October 14th 2009. International Fragrance Association, Brussels, 2009. http:// www. ifraorg. org Inman, R. D., Kiigemagi, U., Deinzer, M. L. Determination of chlorpyrifos and 3,5,6-trichloro-2-pyridinol residues in peppermint hay and peppermint oil. J. Agric. Food Chem. 1981; 29: 321–323.
Inman, R. D., Kiigemagi, U., Deinzer, M. L. Determination of carbofuran and 3-hydroxycarbofuran residues in peppermint hay and peppermint oil. J. Agric. Food Chem. 1983; 31: 918–919.
Juliani, H. R., Simon, J. E. Antioxidant activity of basil. In: Janick J., Whipkey A., eds. Trends in new crops and new uses. Alexandria: ASHS Press; 2002: 575–579.
Karlberg, A. T., Magnusson, K., Nilsson, U. Air oxidation of d-limonene (the citrus solvent) creates potent allergens. Contact Dermatitis. 1992; 26: 332–340.
Karlberg, A. T., Shao, L. P., Nilsson, U., et al. Hydroperoxides in oxidized d-limonene identified as potent contact allergens. Arch. Dermatol. Res. 1994; 286: 97–103.
Karlberg, A. T., Magnusson, K., Nilsson, U. Influence of an antioxidant on the formation of allergenic compounds during auto-oxidation of d-limonene. Ann. Occup. Hyg. 1994; 38: 199–207.
Kaul, P. N., Bhaskaruni, R., Rajeswara, R., et al. Changes in chemical composition of rose-scented geranium (Pelargonium sp. ) oil during storage. Journal of Essentil Oil Research. 1997; 9: 115–117.
Kiigemagi, U., Heatherbell, C. J., Deinzer, M. L. Determination of oxamyl residues in peppermint hay and oil using a radioisotope dilution technique. J. Agric. Food Chem. 1984; 32: 628–633.
Kishore, N., Chansouria, J. P., Dubey, N. K. Antidermatophytic action of the essential oil of Chenopodium ambrosioides and an ointment prepared from it. Phytother. Res. 1996; 10: 453–455.
Kleinsasser, N. H., Kastenbauer, E. R., Weissacher, H. Phthalates demonstrate genotoxicity on human mucosa of the upper aerodigestive tract. Environ. Mol. Mutagen. 2000; 35: 9–12.
Kleinsasser, N. H., Kastenbauer, E. R., Wallner, B. C. Genotoxicity of phthalates. On the discussion of plasticizers in children’s toys. HNO. 2001; 49: 378–381.
Koch, H. M., Drexler, H., Angerer, J. An estimation of the daily intake of di( 2-ethylhexyl) phthalate (DEHP) and other phthalates in the general population. Int. J. Hyg. Environ. Health. 2003; 206: 77–83.
Kreckmann, K. H., Baldwin, J. K., Roberts, L. G., et al. Inhalation developmental toxicity and reproduction studies with cyclohexane. Drug Chemistry & Toxicology. 2000; 23: 555–573.
Kubeczka, K. H. Essential oils analysis by capillary gas chromatography and carbon-13 NMR spectroscopy, second ed. Chichester: John Wiley; 2002. Kumar, A., Nadda, G., Shanker, A. Determination of chlorpyrifos 20% EC (Dursban 20 EC) in scented rose and its products. J. Chromatogr. A. 2004; 1050: 193–199.
Latini, G., Verrotti, A., De Felice, C. Di-2-ethylhexyl phthalate and endocrine disruption: a review. Curr. Drug Targets Immune Endocr. Metabol. Disord. 2004; 4: 37–40.
Lawrence, B. M. Essential oils 1988–1991. Wheaton: Allured Publishing; 1995.
Lawson, L. D., Ransom, D. K., Hughes, B. G. Inhibition of whole blood platelet-aggregation by compounds in garlic clove extracts and commercial garlic products. Thromb. Res. 1992; 65: 141–156.
Li, Q., Nakadai, A., Matsushima, H. Phytoncides (wood essential oils) induce human natural killer cell activity. Immunopharmacol. Immunotoxicol. 2006; 28: 319–333.
Liu, K. H., Kim, J. H. In vitro dermal penetration study of carbofuran, carbosulfan, and furathiocarb. Arch. Toxicol. 2003; 77: 255–260.
Malley, L. A., Bamberger, J. R., Stadler, J. C., et al. Subchronic toxicity of cyclohexane in rats and mice by inhalation exposure. Drug Chem. Toxicol. 2000; 23: 513–537.
Martin, M. T., Brennan, R., Hu, W., et al. Toxicogenomic study of triazole fungicides and perfluoroalkyl acids in rat livers predicts toxicity and categorizes chemicals based on mechanisms of toxicity. Toxicol. Sci. 2007; 97: 595–613.
Matura, M., Skold, M., Borje, A., et al. Selected oxidized fragrance terpenes are common contact allergens. Contact Dermatitis. 2005; 52: 320–328.
Maudsley, F., Kerr, K. G. Microbiological safety of essential oils used in complementary therapies and the activity of these compounds against bacterial and fungal pathogens. Suppor. Care Cancer. 1999; 7: 100–102.
McConnell, R., Hruska, A. J. An epidemic of pesticide poisoning in Nicaragua: implications for prevention in developing countries. Am. J Public Health. 1993; 83: 1559–1562.
Meeker, J. D., Ryan, L., Barr, D. B., et al. Exposure to nonpersistent insecticides and male reproductive hormones. Epidemiology. 2006; 17: 61–68.
Melnick, R. L. Is peroxisome proliferation an obligatory precursor step in the carcinogenicity of di( 2-ethylhexyl) phthalate (DEHP)? Environ. Health Perspect. 2001; 109: 437–442.
Meuling, W. J., Ravensberg, L. C., Roza, L., et al. Dermal absorption of chlorpyrifos in human volunteers. Int. Arch. Occup. Environ. Health. 2005; 78: 44–50.
Miguel, M. G., Figueiredo, A. C., Costa, M. M., et al. Effect of the volatile constituents isolated from Thymus albicans, Th. mastichina, Th. carnosus and Thymbra capitata in sunflower oil. Nahrung. 2003; 47: 397–402.
Misharina, T. A., Polshkov, A. N. Antioxidant properties of essential oils: autoxidation of essential oils from laurel and fennel and effects of mixing with essential oil from coriander. article in Russian. Prikladnaia Biokhimiia Mikrobiologiia. 2005; 41: 693–702.
Naqvi, A. A., Mandal, S. Detection of adulteration in sandalwood oil by GLC. Indian Perfumer. 1995; 39: 62–63.
National Toxicology Program Technical Report 429. NTP Toxicology and carcinogenesis studies of diethylphthalate (CAS No. 84-66-2) in F344/ N rats and B6C3F1 mice (dermal studies) with dermal initiation/ promotion study of diethylphthalate and dimethylphthalate (CAS No. 131-11-3) in male swiss (CD-1( R)) mice. 199. http:// ntp-server. niehs. nih. gov National Toxicology Program Report on Carcinogens. eleventh ed., U. S. Department of Health and Human Services; 2005. http:// ntp. niehs. nih. gov/ ntp/ roc/ eleventh/ profiles/ s150pah. pdf Nielsen, J. B., Nielsen, F., Sørensen, J. A. In vitro percutaneous penetration of five pesticides – effects of molecular weight and