The inquest into the death of Julie McCabe four years ago has finally come to a close – with the coroner suggesting that the black henna tattoo that Mrs McCabe had had done in Dubai four years earlier could have been a factor in raising her sensitivity to the PPD which killed her. PPD, or para-phenylenediamine, is a chemical widely used in hair dye – and in black henna – as it is the only chemical which ensures that black dye remains back instead of fading within weeks, if not days. However, it is also a chemical which has been implicated in innumerable allergic reactions and a significant number of deaths over and above that of Julie McCabe. (For more on PPD see the three articles in the ‘hair’ section of the Skinsmatter website.)
The potential for PPD to cause allergic reactions, even fatal ones, is not unknown so it is worrying that Mrs McCabe apparently visited her doctor numerous times in the six years before her death complaining of rashes, itches and other allergic reactions. Yet it would seem that she was never advised to stop using the PPD-containing hair dye (in her case, made byL’Oreal). Although it is possible that she was so advised but, because nothing else does the dying job as well, ignored the advice. The henna tattoo, presumably just ramped up her sensitivity so that eventually it tipped over into anaphylaxis. It did take another four years before her sensitivity reached that tipping point – but when it did, it did so without warning.
And of course this is the really scary thing about anaphylaxis. It is impossible to predict when an irritating but perfectly manageable allergic reaction will suddenly turn into a life threatening one; sometimes to an allergen that you did not even know you were sensitive to, or because you came into contact with the allergen in a particular set of circumstances.
Why, for example, do small children sometimes have anaphylactic reactions to peanuts when they have never eaten them? Could it be because they have eczema and they have been sensitised to peanut through the peanut oil-based creams used on their skin? Or, how come that someone can have an allergic reaction to wheat after going for a run when, if they have not been running, they can eat wheat with no problems? Or why would someone who got hay fever from birch pollen suddenly find themselves reacting to peach – or someone allergic to latex start to react to avocado or kiwi?
Well, the last two are more comprehensible as we know that latex (a natural rubber) shares proteins not only with avocado and kiwi, but with banana, chestnut, papaya, potato and tomato, while birch shares proteins with a wide range of fruits, some vegetable, peanuts and many herbs and spices. (So could the increase in Oral Allergy Syndrome be down to the massive increase in the incidence of hay fever of the last 50 years? And could that be down to sexual bias in the planting of our trees?……. All to be revealed in the next blog about Tom Ogren’s new book, The Allergy Fighting Garden….)
As regards the peanut sensitisation via the skin. Well whether allergens (or gluten) can be absorbed via the skin is a much argued-over subject in coeliac circles – see Alex’s article from a couple of years ago. But it seems to me that if you can absorbed medication via the skin (and even infect yourselves with helminths via the skin!) why on earth would you not be able to absorb allergens? As for the wheat reactions related to exercise. Dr Andrew Clark at Addenbrookes is currently recruiting for his TRACE study which will try to tease out some of the extrinsic factors (such as exercise) that may affect reactions. Meanwhile, last autumn, Dr Janice Joneja spelled out what we know to date for us here on the FM site.
The one thing that does seem to be glaringly clear is that you cannot be too careful with allergy. While certainly not allowing it to ruin your life, if you have a potential serious allergy, you should take sensible precautions – such as asking your doctor for an Epipen (or alternative) and then always making sure both that it is in date and – far more important – that you carry it with you!