The chemical, p-phenylenediamine (PPD), “is a strong contact allergen used in hair dye known to cause allergic contact dermatitis,” Dr. Cezmi Akdis, of the Swiss Institute of Allergy and Asthma Research in Davos Platz, and colleagues write in the Journal of Allergy and Clinical Immunology.
Both private and occupational exposure to PPD is frequent, but whether it has adverse effects in people with work-related exposure who don’t show allergic symptoms isn’t known, the study team writes.
For the current study, researchers tested the effect of PPD exposure on the activity of genes known to be involved in dermatitis and active in skin that has been damaged. They examined gene activity in skin cells after PPD exposure in seven hairdressers without any skin symptoms suggesting an allergic reaction to the chemical, in four people with mild allergic skin reactions to the chemical and in five people with severe allergic skin reactions.
The researchers found that hairdressers without obvious allergic reactions to PPD still had gene activity changes in their skin that suggest the skin can be damaged even when the PPD doesn’t cause allergic symptoms like a rash.
Hairdressers who apply hair dye to clients several times a day are particularly at risk for PPD exposure. The chemical can also cause allergic reactions in people who regularly dye their own hair, particularly if they use darker colors.
Many salons ask customers to do patch tests to see if they will have an allergic reaction to dye before they get their hair colored, but sometimes this can make people more sensitive to the chemical and lead to a rash when their hair is colored a second time.
Semi-permanent dye may cause less of a reaction than permanent color.
Wearing gloves when dying hair may also reduce the risk of skin damage from PPD.
Photographers who develop film and people who get black temporary tattoos and henna tattoos can also be exposed to PPD and have allergic skin reactions as a result, the authors note.
In the study, PPD exposure resulted in damage to the epidermis, or outer layer of skin, which plays a crucial role in preventing allergens from entering the body and causing damage, the study team notes.
Because they found skin damage both in hairdressers without allergic contact dermatitis and those with mild or acute cases of dermatitis, the results suggest that occupational PPD exposure directly causes skin damage, the study team concludes.