The less sensitizing PPD derivative 2-methoxymethyl (ME-PPD) is currently used in commercial products marketed by P&G, and was shown to be more tolerated by individuals with a history of allergic reactions, according to the study published in the British Journal of Dermatology.
In the study, the research team found that hair dye products with ME-PPD were tolerated by 29 out of 43 (67%) allergic individuals throughout continued hair dyeing with an average of nine treatments per year.
Five individuals reacted upon pretesting, while only mild-to-moderate/marked skin reactions occurred upon hair dyeing in nine individuals who were not identified by the pretest.
“To our knowledge this is the first study among PPD/PTD-allergic individuals indicating that a negative 45-min pretest with a hair dye product helps to avoid severe allergic reactions,” says the study.
In the study, elicitation reactions were studied in 43 PPD and/or toluene-2,5-diamine (PTD)-allergic individuals by a 45 minute pretest with an ME-PPD-containing hair dye on their forearm.
Upon a negative result this was followed by exposure to subsequent hair colour treatments.
Overall, 38 of the 43 PPD/PTD-allergic individuals did not develop an elicitation reaction during the pretest with ME-PPD-containing hair dye products, and were eligible for subsequent hair colour treatments.
Of these 38 PPD/PTD-allergic individuals, 29 tolerated subsequent hair dyeing with ME-PPD-containing hair dye products, while seven showed mild and two showed moderate/marked allergic reactions upon the first hair colour treatment.
The scientists say they decided to investigate the elicitation reactions of ME-PPD in previously allergic individuals because despite a positive patch test reaction to PPD and/or PTD, many people still attempt to continue dyeing their hair with products containing PPD or its derivatives.
The team still mention warnings not to use ME-PPD hair colorants in case of hair dye allergy, and that the results indicate that hair dyeing with ME-PPD-containing hair colour is associated with a certain risk for PPD/PTD-allergic hair dye consumers, with a (cross-)elicitation rate of approximately 30%.
“Based on this experience with the small number of 43 allergic individuals, pretesting with the hair colour product of choice can be considered helpful to provide an alert of a strong (cross-)reactivity, but it is insufficient to provide an indication of the absence of mild to moderate/marked symptoms,” it concludes.