Emerging issues in contact dermatitis
In recent times, there have been a several allergens emerging as causes of allergic contact dermatitis (ACD). These include acrylic nails or shellac nails, the preservative methyisothiazolinone (MI) and the concern with allergy to prosthetic joint replacements.
Acrylic nails/shellac nails
We have recently seen an increase in the number of cases of ACD to acrylic chemicals used in nail cosmetics. While most of these have involved nail technicians, we had a recent worrying case of a consumer who had purchased these products online, for use at home.
There are two types of acrylic nail products that cause problems; the first is the traditional acrylic or gel nail, and the second is Shellac®, which is a newly available type of long-wearing nail polish, which is becoming increasingly popular. The chemicals which can cause allergy in both of these nail products are called acrylates.
Many people are unaware that acrylates are allergenic and can cause ACD, which can result in significant skin problems. Because Shellac® looks like and is applied like a traditional nail polish, it may not be recognized to be acrylate-based. It is also important to note that when ultraviolet (UV) light is required for any nail product, it is indicative that the nail ingredients are acrylates and need curing to progress from the allergenic monomer to the inert polymer state. This includes home style nail packages sold on the TV or internet.
Increasing use of these new acrylic nail products means that dermatologists need to be more aware of the possibility of ACD caused by them. There also needs to be greater understanding of this hazard within the beauty industry. Many beauticians and nail technicians are unaware that a single episode of skin contact with these chemicals may lead to sensitisation and the subsequent development of ACD. Based on international experience, we advise that people protect themselves from acrylates by wearing two pairs of disposable nitrile gloves.
Finally, our experience of testing with acrylates used in nail products has led us to conclude that testing with hydroxyethyl methacrylate (HEMA) alone is an adequate screening agent for acrylate allergy. It was previously recommended that people in contact with acrylic nails were tested with the full methacrylate nail series. However, after reviewing 20 years of patch testing data, we now recommend that people only need to be tested with this one acrylate which is in the Australian Baseline Series, as all patients with ACD to nail acrylates reacted to this one key allergen. This prevents patients having multiple, severe reactions to all the acrylates that they previously would have been tested to.
Prosthetic joints/joint replacements
There has been a growing trend for doctors requesting patch testing for people to metals and other substances used in prosthetic joint replacement surgery. Two particular clinical scenarios include where people are having problems with their joint replacement, or people who report a strong history of problems with metals, prior to a joint replacement. However, scientific support for testing in these circumstances is limited. Some reports state that pre-implant testing offers little benefit. A useful diagnostic algorithm has been developed by Schalock et al titled “Diagnostic algorithm for the evaluation of suspected metal allergy.”
This is summarized below:
If a person does not have a history of reactions to, or problems with metals, they should not be patch tested prior to prosthetic joint replacement surgery.
If a person does have a definite history of problems with metals, there may be some basis for patch testing these people prior to joint implantation, but the evidence is far from clear. The algorithm mentioned above can assist in the decision of whether to patch test or not. Reactions of testing to metals can also be difficult to interpret, as a positive patch test may not be necessarily relevant to a patients’ clinical scenario. Many patients with metal allergies tolerate their joint replacements.
Clinical expertise is essential to interpret these situations, and decisions such as joint removal should not be based on a positive patch test alone. More research is required in this area.
Patch test series at the Skin Health Institute Inc:
The Skin Health Institute have developed a Prosthetic Joint Series for patch testing. This series includes a range of metal allergens, and other substances that may be used during surgery for a prosthetic joint.
Reference: Schalock P, Menne T, Johansen J, Taylor J, Maibach H, Liden C, Bruze M and Thyssen J. Hypersensitivity reactions to metallic implants-diagnostic algorithm and suggested patch test series for clinical use. Contact Dermatitis, 2011, 66: 4-19.
Methylisothiazonlinone
Methylisothiazolinone (MI) is a preservative used in baby wipes and other personal products, which is currently causing an appreciable number of cases of allergic contact dermatitis, an itchy skin rash. Preservatives like MI are needed in moist wipes to prevent bacterial contamination.
Where is MI found?
MI may be found in a range of cosmetic and personal products including:
- Disposable wet wipes including baby wipes and make-up removal wipes
- Shampoos and conditioners
- Body washes and hand cleaners
- Moisturisers
- Sunscreens
- Deodorants
Who is affected?
Interestingly it is the parents and carers using baby wipes on their children who are developing hand dermatitis, caused by allergic contact dermatitis to MI. However it is likely that allergic contact dermatitis involving the nappy area in children and babies may not be diagnosed accurately, and considered just to be nappy rash.
Maternal and Child Health Nurses and medical practitioners, as well as parents of babies and young children, should be aware of the potential for allergic contact dermatitis to develop to MI from baby wipes.
What are the symptoms?
- An itchy red rash on the hands and fingers, or any area of the skin that is coming into contact with this chemical (similar appearance to eczema).
- Babies or young children may present with ‘nappy rash’ that is persistent and resistant to treatment (however there are many factors which contribute to nappy rash for example, contact with urine, faeces, sweating and thrush).
How is allergic contact dermatitis to MI diagnosed?
Patch testing involving the back over several days (not prick testing) is used to diagnose allergy to MI.
How to prevent allergy to MI?
All users of baby wipes should check packaging to ensure that the product does not contain MI. NOT ALL WIPES CONTAIN MI. Other products used should also be checked for this preservative as well.
People with unexplained rashes should check the label of ingredients and see if it contains MI.
Alternative products should be used if necessary.
Where to get help?
If products containing MI are avoided and yet the rash persists, treatment should be sought from GPs and/or dermatologists.
Advice from the Skin Health Institute can also be sought. Phone Amanda, 03 9623 9402 or email apalmer@occderm.asn.au
Letter to the Editor “Methylisothiazolinone in baby wipes: a rising star among causes of contact dermatitis” is available in the Medical Journal of Australia 2014; 200 (4): 208.
For more information visit other sections on the website for more details about MI.