Foreword

It has been 14 years since the second edition of Patch Testing was published. Inevitably, after such a long period, some of the data presented at that time are now incomplete, incorrect or possibly even outdated in the light of current knowledge in the field of contact dermatitis. In this third edition, we have added new information on contact allergens published from 1994 to march 2008 in all volumes of the journals Contact Dermatitis, the American Journal of Contact Dermatitis and its successor Dermatitis and updated existing knowledge.

Approximately 650 new allergens have been found and are presented with suggested patch test concentration(s), vehicle(s) and additional relevant information. Thus, about 4350 chemicals are now included in 'Table 1. Chemicals', the beating heart of the book, with an additional 2200 (often new) synonyms. Chemical databases available on the internet such as The United States National Library of Medicine's ChemID Plus Advanced were searched for the identity of unfamiliar chemicals, which has resulted in correcting nomenclature errors and identification of several synonymous chemicals which were previously not recognized as such and had separate entries.

The number of references has increased by 120% and many older literature references have been replaced with more recent ones. For all chemicals that have a monograph in the Merck Index, the CTFA Ingredient Dictionary and Handbook or both, references had to be adapted, as both these classic and important works have recently (2006) appeared in new editions. In addition, the relevant patch testing information in new editions of two previously already referenced textbooks, Contact Dermatitis (4th Edition, 2006) and Fisher's Contact Dermatitis (6th Edition, 2008, kindly provided prior to publication by prof. Robert Rietschel) have been incorporated in this edition, as has data from the new Handbook of Occupational Dermatology (2004). All information on allergens commercially available from the major European suppliers (Brial, Chemotechnique, Trolab) has been updated.

Another major change has been in the system of the nomenclature, as since the previous 1994 edition the new INCI (International Nomenclature Cosmetic Ingredient) has been introduced in Europe, the United States, Japan and many other countries. For botanicals, for example, (including the many essential oils presented here) entirely new names have been introduced based on their genus and species names and the system for colors has also changed. As we decided to base the alphabetical entries ('preferred names') on the INCI system, major adaptations in the book were necessary. Further changes in this book, the format of which has remained essentially the same, include a structural improvement of tables 3 ('Groups of chemicals and substances') and Table 4 ('Products') with division into several chapters for quick and easy reference.

Even in this day of digital and on-line information, we think that a printed book ('hard copy') best suits the requirements of patch test departments that information can be looked up quickly, anywhere in a dermatology unit and by everyone needing it. However, the high cost of producing books preclude frequent updates. Therefore, we are currently working on the development of yearly digital updates accessible online and/or in the form of an Ebook.

ANTON C. DE GROOT