All (consecutive) patients
Baseline series with fragrance screening markers
Patients with history of fragrance intolerance
PT selected own products
PT additional fragrance series from the start
Patients with positive PT reaction to fragrances/fragranced products
PT 2nd round supplementary to above
PT single ingredients (obtained from manufacturer) of positive product; fragrance mixture in creams, etc., often provided as mixture; may need additional breakdown testing
ROAT, if PT reaction is doubtful (equivocal) or to verify and establish current relevance of a positive PT reaction
Outcome
Discuss and evaluate relevance based on labelling information
Counsel patient regarding avoidance (also if mixes were positive without mix breakdown having been tested or remaining negative)1
12.5 Prevention
Primary prevention means, in this context, the avoidance of new cases of sensitisation to a fragrance substance, that is, healthy persons should not get sensitised. Secondary prevention basically means that persons who already got sensitised avoid future contact to their allergen(s) to prevent relapses of allergic contact dermatitis. Tertiary prevention, which implies limiting the severity of an existing disease by intensive and often continuous or repeated care (also called rehabilitation), has a role in the management of contact allergic patients only in the rare instances where allergen avoidance is not possible. Some components of prevention by different actors are outlined in Table 12.2.
Table 12.2
Different measures of prevention concerning an allergen ‘X’
Measure | Primary prevention | Secondary prevention |
|---|---|---|
Information (labelling) | Consumer: decision not to buy a product containing X | Dermatologist: enable adequate diagnostics |
Patient: avoidance of all products containing X | ||
Formulation/substitution | Producer: deliberate avoidance to use X in products | …Will increase choice of products for patient with contact allergy to X |
Restriction of use concentration | Regulator/producer: reduce substantially the likelihood of new sensitisation to X in consumers | …Will possibly allow the use of X in some product categories for weakly sensitised patients |
Prohibition | Regulator/producer: eliminate risk of sensitisation to X in consumers | …X will become irrelevant for patients in those products for which ban is effective |
Different means, if partly overlapping, are used to achieve above objectives regarding contact allergens in general and fragrance substances in particular. Premarketing screening of newly introduced substances regarding different toxicological endpoints, including contact sensitisation, aims at identifying a hazard at a sufficiently early stage, with the consequence of (1) not marketing the substance, (2) establishing use concentration limits or (3) classifying the substance as ‘safe without restrictions’. This process aiming at induction and primary prevention, respectively, has been formalised by industry in terms of a ‘quantitative risk assessment (QRA)’ [1]; however, several aspects of this process are currently under revision, and it cannot yet be considered as validated. Time and again the premarketing screening fails and substances are introduced into the market, which turns out to be clearly not safe for the consumer in the concentrations and types of products, respectively, they are used in. This is illustrated by clinical data (an infamous example being HICC), which should prompt a reassessment and the redefinition of a safe use level, best based on the dose-elicitation relationship in sensitised persons. Thereby, patch test data, beyond the purpose for diagnosing and counselling one given patient, help to improve product safety and thus aid primary prevention, if sufficiently standardised and collected in a surveillance network.
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