Wet wipes have been accused of a lot of things – creating ‘fatbergs’ in sewage systems, adding to the microplastic threat to marine life, preventing the breakdown of solid matter in landfill sites and causing skin rashes both on the bottoms of the babies on which they are used and on the hands of the parents using them. And now they are being accused of triggering food allergy!
An article in Saturday’s Telegraph linked the use of wet wipes to the development of food allergy. The theory is that the chemicals found in wet wipes may heighten the risk of an atopic baby (one who is already genetically disposed to have an allergy) becoming sensitised to food allergens that it may it may encounter on the skin – a sibling or a parent with peanut butter on their hands transferring that to the baby. While this is possibly stretching the demonisation of wet wipes a bit far, the research which gave rise to the story raises much more serious questions over allergen sensitisation via the skin.
The study which triggered the article appeared in the Journal of Allergy and Clinical Immunology last month. It showed that if you skin sensitise neonatal mice with food allergens, and then you challenge them orally with those allergens (e.g. you made them eat them) they will have an allergic, and possibly an anaphylactic reaction to that food.
Despite the Telegraph‘s headlines, this is not ‘new’ news. There have been a number of studies showing that where the skin barrier is damaged, allergens (such as peanut oils) can penetrate and sensitise the immune system so that when it next encounters that allergen (in a food) it reacts to it. If, on the other hand, the immune system first encounters the allergic protein via the gut (when it is eaten) it does not see it as harmful and does not react. This was clearly demonstrated in the LEAP study in 2015 which showed that if you fed peanut proteins to at-risk infants from a very young age you dramatically reduced the risk of them developing peanut allergy later.
However, this study raises, a far more worrying issue both as far as allergic patients and the allergists treating them are concerned. If it is not only possible but easy to sensitise an atopic person, be they adult or child, to an allergen via the skin, could the skin prick tests, which are designed to diagnose allergy by deliberately introducing an allergen through the skin, not actually induce that allergy?
That is exactly what worries – and has worried – Dr Janice Joneja (Dr Joneja of our Beginners and Comprehensives Guides to Histamine Intolerance) for some years. She has never used skin prick testing in her own practice and is deeply concerned that her colleagues continue to do so. And do so despite:
- Mounting evidence of allergy sensitisation through the skin
- The fact skin prick testing itself has never been tested for safety – and
- The fact that skin prick testing is widely recognised to be extremely unreliable producing a large number of false positives (‘diagnosing’ an allergy which does not exist) and false negatives (failing to diagnose an allergy which does exist) – and that there are other tests available which use blood drawn from the body rather than injecting allergens into it.
As she says:
‘There are no published research studies to prove either the danger or the safety of skin testing. Any invasive technique requires extensive research before it is approved for use….. No such studies have been carried out on skin testing, although thousands of such tests are performed every day in medical offices and clinics throughout the world. Because the techniques of skin testing – prick, scratch, intradermal and patch delivery of the allergen – have been employed for decades, little thought has been given to the immunological processes involved in the tests although immunological responses clearly occur witnessed by the wheal and flare reaction.
An immunological response is not trivial….. indeed it is the process involved in vaccination. Vaccines are delivered by injection, and more recently via skin patch – similar to the techniques used in skin testing. But while no vaccine is approved for use without extensive testing on both animals and humans, skin testing has never been tested for safety on either humans or animals.’
For Dr Joneja’s article on the subject see here on the Foods Matter site.
So where does this leave parents of atopic infants? As one of our readers, the mother of two children with multiple and severe food allergies, says:
‘Our sons have been undergoing these skin prick tests since they were toddlers and, as with many children with allergies, very often their first contact with a particular food allergen was through the skin for these diagnostic tests. For example, our eldest son had never knowingly eaten any type of nut or seed before a skin prick test revealed him to have severe allergies to peanuts, hazelnuts, cashew nuts, pistachio nuts, brazil nuts and sesame seeds.
He is a highly allergic child, so he might well have developed allergies to these foods had he first been exposed to them as a food. However this mouse research suggests that eating an allergen before being exposed to it via the skin makes it much less likely that someone will react. So I am left wondering about the safety of all the skin-prick testing he underwent and whether some of his allergies were actually triggered by the tests themselves.’
17th May 2018
Dr Adam Fox is consultant paediatric allergist at a leading London children’s hospital. He is President Elect of the British Society of Allergy & Clinical Immunology and chairs their Paediatric committee. He is also trustee and Chair of the Advisory Board of Allergy UK, and member of the Anaphylaxis Campaign Clinical and Scientific Panel.
In response to Dr Joneja’s article he says:
‘Skin prick testing is internationally accepted as a safe method of allergy testing and is endorsed by organisations around the world as part of standard allergy practice eg NICE, European and American Allergy academies. Whilst there has been longstanding interest in the role of skin exposure to allergens as a way of developing sensitisation, this is quite distinct from skin prick testing and there is no published evidence at all to suggest that skin prick testing in anyway contributes to the development of allergies.’