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Essential Oils: Contact Allergy and Chemical Composition

Essential Oils: Contact Allergy and Chemical Composition by Anton C. de Groot and Erich Schmidt. Boca Raton, FL: CRC Press; 2016. Hardcover, 1058 pages. ISBN: 978-1482246407. $199.95.

At last, serious and reliable scientific books about essential oils have started to appear in the market. The Handbook of Essential Oils: Science, Technology and Applications has been published in two editions (2010, 2016) in the last six years. I consider Essential Oils: Contact Allergy and Chemical Composition, with its 1,000-plus A4-size pages, to be complementary.

Anton C. de Groot, PhD, is a dermatologist with a special interest in contact allergies. Erich Schmidt is an industry-based essential oil specialist. Their joint efforts have given rise to a comprehensive book on essential oils with particular emphasis on allergic reactions. Scanning the literature, they have identified 79 essential oils with a record of contact dermatitis and compiled chemical data and allergy information about 93 materials (91 essential oils and two absolutes). The book lists 4,350 chemical substances found in those oils and treats them critically with proper literature references. Such comprehensive information is difficult to find in a single book. Therefore, it will be a valuable source for essential oil researchers.

The introductory chapters on essential oils are short but informative, and provide the basics while emphasizing the correct terminology, which is necessary. Contact allergy and allergic contact dermatitis are discussed in general, and specific, related information is provided for each oil and absolute. All the essential oils and absolutes mentioned in the book are traded and used by food, cosmetics, pharmaceutical, and perfumery industries.

Chapter 5 comprises individual monographs on each of the 93 products. Each monograph contains a definition, source information (plant species and part yielding the oil), INCI (International Nomenclature of Cosmetic Ingredients) name, CAS (Chemical Abstracts Service) registry number, EINECS (European Inventory of Existing Commercial Chemical Substances) number, ISO (International Organization for Standardization) information, chemical information, uses, and chemotypes (if any). Contact dermatitis/allergy data are provided in brief, and known constituents of the oil are listed in tabulated form complete with footnotes and references. Major constituents are listed with percentage limits in a separate table. These lists contain information extracted from literature as well as Erich Schmidt’s personal unpublished data.

In Chapter 6, compounds found in essential oils are listed alphabetically with reference to related oils in which the compounds have been identified. Chapter 7 contains synonyms of the listed compounds, and the book ends with an index.

The only thing I may criticize is that 26 substances that are restricted in the European Union have not been covered, even briefly. Most of those volatile substances, such as methyleugenol, pulegone, alpha- and beta-thujone, coumarin, estragole (methylchavicol), menthofuran, beta-asarone, and safrole, frequently are found in essential oils. Reference to those compounds in the book could have been useful to the general reader, since the compounds often are the subject of toxicological concern.

The book is a useful source of information on essential oils. I recommend it to all those interested in essential oils, and in particular to dermatologists, nurses, and other health care professionals; students, workers, and experts in food, agriculture, pharmacy, cosmetics, and perfumery sectors; and aromatherapists.

—K. Hüsnü Can Başer, PhD
Near East University,
Faculty of Pharmacy Department of Pharmacognosy
Nicosia, Northern Cyprus