Henna is used often in the United Arab Emirates, as it is part of their culture and tradition to use it. Allergy to the usage of natural henna is normal, but adding the substance PPD (para-phenylenediamine) to natural henna increases the risk of allergic contact dermatitis.
What is PPD?
Molecular formula: C6H8N2
Molecular Weight: 108.14g/mol
Melting Point: 145 to 147 ˚C
Para-phenylenediamine is a white to light purple powder that darkens on exposure to air, and is slightly soluble in water. It is most often used in hair dyes, fur/textile dyes, a photographic developing agent and also as an antioxidant in rubber compounds.
Individuals exposed to PPD could cause:
1. Severe dermatitis
2. Eye irritation and tearing
3. Asthma
4. Gastritis
5. Renal failure
6. Vertigo
7. Tremors
8. Convulsions
9. Coma
PPD is a very strong potential skin sensitiser; adverse effects could be observed after repeated use/exposure.
It is mixed with henna recently, as it's able to give an ebony colour instead of the red/orange colour that natural henna gives. It is also able to shorten the tattooing process by about one to two hours and lasts longer than natural henna does.
So what's so bad about contact dermatitis, and what about it makes it so much worse than the original allergy towards natural henna?
The allergic reaction from natural henna is of Type I, whereby people might get a tight feeling in their chest, sneezes, runny nose, coughs and itchy eyes after awhile.
Contact dermatitis however, is not immediate. It could occur up to 10 days after exposure so patch tests would not work. Plus, since it's a Type IV reaction, even if no reaction occurs the first few times after use, the probability of an allergic reaction could increase after repeated use.
Symptoms of contact dermatitis includes having a red, patchy and streaky rash. The rash itself might have red bumps, feel warm and tender or may ooze, drain or crust or might also become scaly, raw or thickened.
