Contact Dermatitis • Editorial CODContact Dermatitis

The methylisothiazolinone epidemic: Is the fire out or is Rome stillburning?doi:10.1111/cod.12204

The story of the epidemic of contact allergy tomethylisothiazolinone (MI), a preservative permitted upto 100 ppm in cosmetic products, is a sorry one. Clinicaldermatologists gave repeated warnings of the emergingepidemic with a plea for urgent action by both regulatorsand industry (1). The dramatic rise in the rates of reportedcases of contact allergy to MI has been unprecedented inEurope with the increase primarily caused by increasingconsumer exposure to MI from cosmetic products. Thedelay in re-evaluation of the safety of MI in cosmeticproducts has adversely affected consumer safety. From MIitself being a rare allergen 3 years ago, there are presentlyup to about 10% of some patch tested populations allergicto it (2). History will record the ineptitude of the regulatorsto tackle the problem when warned and the dismissivepublic relations statements broadcast by industry.

MI is now included in the European baseline series (3).Patch testing is sensitive and specific as a diagnostic tool.The elicitation of contact allergy under diagnostic patchtest conditions is intended to show whether an individualpatient has contact allergy to a substance or not and offersthe first indication that exposure to a substance is causingallergy in the population and is a means of followingcontact allergy trends over time (4). An obvious increasein the frequency of sensitisation in the consumer showsthat there has been a failure of risk assessment and/ormanagement of the risk. But yet again we have seenpowerful clinical data being ignored or doubted due tofalse assumptions or naivety. The consumer is the guineapig and the clinical data from investigating the consumermust never be dismissed; consumer exposure is the mostinstructive of all experiments.

On 12 December 2013 the Scientific Committee forConsumer Safety of DG Sanco (Consumer Safety &Health Protection), European Commission adopted anOpinion (5) that MI should not be used in leave-oncosmetic products (including wet wipes) and restricted to15 ppm (the same as the methylchloroisothiazolinone/MImixture) in rinse-off products (it is unknown whetherindividuals with contact allergy to methylisothiazolinonewill react to such levels of exposure).

‘Coincidental’ with the above, European industry,represented by Cosmetics Europe, issued an advisorythat methylisothiazolinone should no longer be used

in leave-on cosmetic products, including wet wipes (6).The latter advisory refers to the concerns raised by theEuropean Society for Contact Dermatitis and evaluationusing quantitative risk assessment (QRA) but makes noreference to rinse-off products. There is no discussion asto why QRA exercises have been undertaken at this latestage to address a problem, and were not used as a toolto prevent the epidemic. This is particularly importantas we are aware that (as yet unpublished) industry datausing the QRA for MI indicates that it was unsafe inmany cosmetic product types. It is another example ofQRA being applied retrospectively and not prospectivelyto protect the consumer.

Labelling, a risk management tool, is helpful to aconsumer who has a known contact allergy. It isunknown what proportion of the general populationis now sensitized to MI but not confirmed as sensitizedby diagnostic patch test investigations. This proportionneeds protection, which may be achieved by ensuringthat any future exposures are appropriately small.

Consumers cannot find information on the presence ofMI in products except cosmetics and household detergentsbecause, as yet, there is no harmonised classification of MIas a skin sensitizer. The risk for skin sensitization by MI isat least equivalent to that of other substances whichhave received a harmonised classification accordingto the CLP Regulation. Classification under CLP isurgent.

It will be some time before we see the rates of reactionsto MI in patch tested populations plateau and thendecrease. It will be then yet another dramatic exampleof the Dillarstone phenomenon (7). Meanwhile, morecitizens will become sensitised to MI; clearly, leave-oncosmetic products containing MI at 100 ppm are unsafeand in a society where consumer safety is a claimedpriority perhaps such products should be removed fromthe shelves?

Whilst the MI problem will, belatedly, be resolved inEurope, one would hope that manufacturers and suppliersof MI will, as a priority, advise on restricting the use ofMI in all their markets. It will be inexcusable if theepidemic is experienced in other geographical regions; ifit is, it will indicate monumental negligence, contemptand greed.

© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons LtdContact Dermatitis, 70, 67–68 67

EDITORIAL

Regrettably, no doubt in a few years we will experienceanother catastrophe. When methyldibromo glutaronitrilewas finally removed from all cosmetic products in Europe(June 2008) ‘only’ up to about 4.5% of patch testedpatients were sensitised (8). Have the lessons from thatbeen learned? Apparently not. Will the lessons from MIbe learned? Probably not.

Industry must have faith in the clinical data generatedand given freely by the dermatological community.Together we will be stronger and society will benefit.Safety cannot continue to be a competition.

The Editors

References1 Goncalo M, Goossens A. Whilst Rome

burns: the epidemic of contact allergy tomethylisothiazolinone. Contact Dermatitis2013: 68: 257–258.

2 Johnston G. The rise in prevalence ofcontact allergy to methylisothiazolinone inthe British Isles. Contact Dermatitis 2013(submitted).

3 Bruze M, Engfeldt M, Goncalo M, GoossensA. Recommendation to includemethylisothiazolinone in the Europeanbaseline patch test series. (On behalf of theEuropean Society of Contact Dermatitis(ESCD) and the European Environmentaland Contact Dermatitis Research Group

(EECDRG)). Contact Dermatitis 2013: 69:263–271.

4 Basketter D A, White I R. Diagnostic patchtesting – does it have a wider relevance?Contact Dermatitis 2012: 67: 1–2.

5 Scientific Committee on Consumer Safety(2006), DG Sanco European Commission.Opinion on methylisothiazolinone (P94)submission II (sensitisation only), Adoptedon 12 December 2013. Available at:http://ec.europa.eu/health/scientific_committees/consumer_safety/docs/sccs_o_145.pdf (lastaccessed 27 December 2013).

6 Cosmetics Europe 2013. Cosmetics Europeissues recommendation to discontinue use

of MIT in leave-on skin cosmetic products,13 December 2013. Available at:https://www.cosmeticseurope.eu/news-a-events/news/647-cosmetics-europe-recommendation-on-mit.html (lastaccessed 27 December 2013).

7 Dillarstone A. Cosmetic preservatives.Contact Dermatitis 1997: 37: 190.

8 Scientific Committee on ConsumerProducts 2006. Opinion on methyldi-bromoglutaronitrile (sensitisation only),Adopted 20 June 2006. Available at: http://ec.europa.eu/health/ph_risk/committees/04_sccp/docs/sccp_o_060.pdf (lastaccessed 27 December 2013).

© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd68 Contact Dermatitis, 70, 67–68