PCS.05 Establishment of safe exposure limits for the induction of allergy. Practical examples

Abstract

The WHO criteria for drug allergy can be adapted as guidelines for primary sensitisation from consumer products or occupational exposures. In case a person with a formerly healthy skin, develops allergic contact dermatitis after a specific exposure (a product or occupational exposure) has a positive patch test to specific chemical present in the product and ideally a positive either patch test or use test to the product during re‐exposure primary sensitisation is likely.Allergic contact sensitisation is a unique toxicological event (e.g. compared to cancer) as there is a direct (time and skin area) correlation between exposure and disease and the basic damage on the individual can be identified by the diagnostic patch test. Primary sensitisation may occur after single exposure to potent allergens, experimental from DNCB, in the US poison ivy, occupational accidental exposure to isothiazolones (in%) or from hair dying with PPD and its derivatives as a flare‐up reaction occurring 1–2 weeks after the original exposure.The ongoing epidemic caused by methyldibromo glutaronitrile (MDGN) provides unique options for studying primary sensitisation from consumer products as the clinical reactions are often very severe and patch test reaction with the products often exceeds the strength of the standard patch test response. Chemical analysis of the products involved uniformly illustrates the presence of MDGN within the legal permitted concentration. At the start of the epidemic, primary sensitisation was mostly seen from leave on products. After EU actions in 2002 against the use of MDGN in leave on products primary sensitisation from this preservative is now caused by wash off products. This observation is significant as it underscores the effect of specific exposures for primary sensitisation from consumer products but also the fact that primary sensitisation from a moderate to strong hapten is possible from wash off products. The MDGN story has illustrated that human data are pivotal for the current risk assessment – risk management. No new chemical should be permanently permitted in consumer products before significant post marketing data, collected after stringent criteria, are public available and scrutinised by an independent scientific committee.Human sensitisation data has successfully been used to introduce regulation of nickel exposure from consumer items. The year 2000 EU regulation has been in use in Denmark for more than 10 years. A significant decline in both induction and elicitation of dermatitis from nickel releasing items has been observed. Health economists have calculated that the direct savings from the regulation amount to 1.2 bill Euro over a 20‐year period in a population of 5.2. mio individuals.Translated to the whole EU‐region substantial gains can be achieved by improving the contact allergy risk assessment – risk management process.