The usual suspects and some new offenders share the space in the Skin & Cancer Foundation’s 2018 top 10 of contact dermatitis allergens.
Nickel, chromate and thiuram came in seventh, ninth and tenth places respectively – highlighting that while their potential to cause contact dermatitis is well known, it can still be extremely difficult to avoid exposure.
Speaking to the limbic ahead of her presentation at the Australasian College of Dermatologists Annual Scientific Meeting in Melbourne, Dr Adriene Lee said occupational exposures in particular were fraught with complexities.
For example, construction workers may seek to avoid exposure to chromate in cement by wearing leather gloves. Unfortunately the well-recognised allergen is also used in the tanning process to increase the durability of leather products.
Dr Lee, who is also Dean of Education for the College, said an interesting finding this year was that five of the 10 top allergens were fragrance allergens.
Topping the list in first and second positions were the hydrogen peroxides of limonene and linalool.
“They are extracts from herbs and citrus peel so a lot of our patients think of them as natural products and they will be in a lot of natural products.”
She said people can be hard pressed to find hand washes, moisturisers, shampoos, conditioners and detergents that don’t contain the allergens.
“It may be labeled as a fragrance or just come up as limonene or linalool. It’s hard to avoid unless you know the names.”
“It’s a trend across the world and certainly our data is showing they are taking over in a way. It’s interesting. I knew we were seeing reactions but I didn’t realise we were seeing that many.”
Fragrance Mix 1 was the third most common allergen, Balsam of Peru came in fifth position and Fragrance Mix 2 was in eighth position.
“If we look back at the data from 2000 to 2010, there were only a couple of fragrance allergens in the top 10 but now it’s five. And maybe five years ago the commonest allergen was a preservative methylisothiozlinone (MI).”
“We often talk about MI as it caused an epidemic of preservative allergy around the world and then got banned in Europe in leave-on products and is now very limited in its use in wash-off products.”
“So the rates of that have reduced but it is still in our top 10.”
MI alone come in sixth position while a mix of MI and methylchloroisothiazolinone (MCI) was in fourth position.
Regulation lacking in Australia
Dr Lee said that Australia was lagging behind Europe in regulation of common allergens.
“We just get the positive fall out from bans in the EU basically.”
She said Australians had some protection from allergens that were banned in consumer products in Europe and as a consequence were no longer on our supermarket shelves either.
However other European initiatives such as the addition of ferrous sulphide to change the allergen potential of chromate in cement, did not flow through to Australia.
Dr Lee said the Skin & Cancer Foundation’s top 10 would be a close reflection of what is happening elsewhere in Australia.
“Certainly the fragrances and MI. Allergens like thiuram and chromate might be higher in our clinics because we do an occupational clinic so we do pick up a bit more.”
She said patch testing was most useful for patients who were constantly getting dermatitis, doing the right things but not getting better.
“If we have the opportunity to patch test and give them the name of the chemicals that are causing their dermatitis, then that’s fantastic.”
“Also with work-related exposures, if we can test them and work out what’s going on, they can change how they are working, use gloves or change the product they are working with. Then we can usually keep them in their occupation rather than going on to workers compensation or WorkCover. That’s where we think we have our most important roles and wins.”
She added that the Skin & Cancer Foundation offers access to a contact allergen bank – a repository for many of the less common allergens that dermatologists may need for patch testing their patients.
Top 10 Contact Allergens
- Limonene hydroperoxide
- Linalool hydroperoxide
- Fragrance Mix 1
- Methylisothiozlinone (MI) & methylchloroisothiazolinone (MCI) preservatives mix
- Balsam of Peru
- Methylisothiozlinone (MI) preservative
- Fragrance Mix 2