Unveiled in a test conducted by the Consumer Council on 25 models of permanent hair dyes available in market, skin sensitizers were found in all the products tested, though with different concentrations. One of the models was found to contain one sensitizer exceeding the relevant maximum limits set by both Mainland China and the European Union (EU). Some overseas studies advised that even a small amount of sensitizers may trigger allergic skin reactions. Consumers are cautioned to select hair dye products carefully.
The test, which covered 20 home-use hair dyes and 5 other models claimed for professional use, revealed presence of two or more types of skin sensitizers in 23 samples. While 1 model found containing as many as four types, 10 others found with three types of sensitizers. A dermatologist advised that presence of multiple sensitizers in hair dye products will increase chances of allergic reaction and its severity.
Regarding types of sensitizers, p-phenylenediamine (PPD) was found in 10 models with a concentration between 0.25% and 1.7%, while toluene-2,5-diamine (PTD) was found in 18 models with a concentration ranged between 0.029% and 2.3%. Both PPD and PTD are classified as extreme sensitizers. Although concentration of these sensitizers found in the tested products complies with standards in Mainland China and the EU, overseas studies indicated that concentration even as low as 1% of these substances might cause allergic reaction in some people already.
Besides, m-aminophenol (MAP), a strong sensitizer, was found in 20 models with a concentration between 0.041% and 2.5%. MAP found in one model at 2.5% has exceeded the maximum limit set in Mainland China (2%). To mix the colorant and developer reagents of the same model at the mixing ratio of 1:1, the mixture is calculated to contain MAP at 1.25%, which again has exceeded the maximum limit of EU at 1.2%. The Council has already notified related supplier of the test result.
Symptoms of an allergic reaction to hair dye include rash, flaking and itching. For severe cases, the face, forehead and eyelid may swell and formation of blisters as well as scalp and ear areas may fester. Such symptoms could develop within hours or over one to two days' time after hair dyeing.
Tested at their respective recommended contact time (from 15 to 60 minutes), none of the 25 models were found to contain NDELA (A carcinogenic substance N-nitrosodiethanolamine) in their mixture. Nevertheless, a small-scale study conducted by the Council discovered that NDELA could be formed when the colorant and developer reagents of selected models were left idle for a prolonged period of time after mixing. Therefore, the Council advised consumers to strictly follow the recommended contact time when using hair dye products.
In terms of product labelling, two PPD and or PTD-containing models were found to have missed out the ingredients, the concentration as well as the bilingual warning statement as required by the "Pharmacy and Poisons Ordinance". Another four models have missed out the warning statement or concentration of these two sensitizers. The Council has referred information of relevant products to the Department of Health for further action deemed necessary.
The Council also urged manufacturers to disclose ingredients in great details to facilitate consumers in identifying presence of allergy-causing substances as well as their concentrations.
Ammonia was found in 15 models tested with a concentration between 0.35% and 1.67%, but all meet standards in Mainland China and EU. One model which claimed "low Ammonia" on its pack print was found containing 1.13% of this compound, a concentration relatively high among the 15 models. Moreover, heavy metals like lead, arsenic and mercury though found in 22 models, their concentrations were in compliance with the standards in Mainland China and Canada, which was considered as satisfactory.
Here are some tips for consumers when using hair dyes:
- Read product instruction, ingredient list and their content details thoroughly before use, follow the recommended contact time and avoid prolonged application.
- Avoid using hair dyes models intended for professional use as their user instructions are usually more complicated.
- Perform a skin allergy test on your skin before dyeing your hair. People with sensitive skin should avoid hair dye products containing PPD or PTD. Consider products with lower concentration of sensitizers or lighter shade if necessary.
- Minimize the chance of skin allergy during hair dyeing by applying Vaseline to the hairline, ears, forehead and neck in advance.
- Don't use on wet hair, apply heat or wrap cling film around the head which may increase chances of scalp sensitization.
- Wear protective gloves when apply hair dye mixture and prevent direct skin contact.
- People with skin diseases, or wound on scalp, pregnant women and breastfeeding mothers should stop hair dyeing temporarily.
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