ABSTRACT
I. Introduction 130
II. Dose-Response Studies with Contact Allergens 131
A. DNCB 131
B. Metals 132
C. Kathon CG 135
D. Other Allergens 137
III. In-Use Tests with Contact Allergens 137
IV. Conclusions-The Relationship to the Hands 138
References 140
I. INTRODUCTION
Although everyone recognizes that higher levels of a contact allergen and/or a greater degree of skin exposure will render both the primary induction of the allergic state and elicitation of dermatitis in a sensitized individual more likely, in very few cases it is possible to give a quantitative view of the response that will follow a certain level of exposure. Also, it is important to recognize that for many individuals years of exposure to a well-recognized contact allergen will still fail to result in the expression of any clinical disease. Nevertheless, we are not in complete ignorance. It has long been understood that contact allergy is a dose-dependent phenomenon. We are aware that 2,4-dinitrochlorobenzene (DNCB) is a potent contact allergen for which a single skin contact with a sufficient dose may well be sufficient to induce an allergic status in most people.1 In contrast, although chromates are strong sensitizers in predictive
models, until recently the most common cause of chromate allergy was persistent contact with trace levels in cement.2 Here the average time to a clinical problem was 10 or more years. A third scenario is represented by such potential allergens as paraben preservatives and the cetostearyl alcohols, which seem to be extremely ineffective sensitizers, partly because they are widely and safely used in skin products. However, when used on the damaged skin of a stasis ulcer, even these chemicals can represent a significant problem.3 So, in this chapter we will examine what is known of quantitative aspects of the induction of contact allergy and the elicitation of allergic contact dermatitis, and also consider the factors that, in our view, may have a profound influence on quantitative considerations, particularly in relation to the hands.
