Some hair dye brands have reacted to consumer concerns about the safety of PPD by labelling their products as ‘PPD free’ or ‘without p-phenylenediamine’.
These products sound like a great option for those people who suffer from a PPD allergy, but there are big concerns around many of them because, while PPD free, they instead contain another substance - paratoluenediamine, or PTD. PTD is a very similar compound to PPD and often has identical effects on sensitive users.
As with PPD, accurate statistics are hard to come by and there has as yet been no definitive determination of how many people with a sensitivity to PPD are also allergic to PTD. But a couple of studies have suggested figures of either 43% or 57%, so it’s important to know that if you have been diagnosed as allergic to PPD, you can’t simply switch to a product marked ‘PPD free’ without first being tested for sensitivity to PTD. Several other so called ‘aromatic amine’ compounds, which all perform a similar role in hair colour products, are also thought to pose a significant risk to users diagnosed with a PPD allergy.
Always check the pack for ingredients, and always perform a skin test.