A South African study of commercially-available hair relaxers has found that every relaxer tested, regardless of active formulation or whether they were marketed as suitable for children, have pH levels high enough to damage the user’s skin and may contribute to high rates of alopecia seen among women in the country.
A press release from the University of Cape Town, South Africa, where the research was conducted, notes that investigators evaluated 121 hair relaxer products, of which 54% were international brands.
All studied products had pH levels higher than 11.5, which the authors say is considered corrosive to the skin by both global and local occupational health and safety guidelines.
The researchers purchased relaxers from various retailers in Cape Town, which they recognized as a limitation to the study.
Ntombenhle Sishi, a cosmetic formulations scientist and co-author on the paper, explained, in the release: “Every cosmetic product lists ingredients. We classified the relaxers according to the three chemical actives: sodium hydroxide, calcium hydroxide and lithium hydroxide. Of the 121 products, 76 fell under the sodium hydroxide category, 24 were calcium hydroxide and 21 were lithium hydroxide.”
The paper was published in The South African Medical Journal (Nov. 2019; 109(12):941-946).
So-called no-lye hair relaxing kits, which typically use calcium hydroxide as the active agent, are considered safer than sodium-based relaxers and are often targeted to children, the press release notes.
“One such product [examined in this study] is a relaxer with an activator that must be mixed into it,” said Sishi. “It was packaged with a conditioner, which is usually meant to protect the hair and scalp. We wanted to simulate real-life conditions according to the manufacturer’s instructions, yet we found that the maximum pH was 13.8—almost 14. Worryingly, this was meant to be used on children.”
“The skin of a child is not yet fully developed, and so should not be exposed to such a high pH—not that adult skin should be either.”
Six of the 76 sodium hydroxide products, four of the 24 calcium hydroxide products and eight of the 21 lithium hydroxide relaxers were targeted at children, researchers found. Sishi noted that research from 2007 from the university found that four out of five school children in South Africa relaxed their hair.
This use of caustic products can have a long-term impact on the scalp. Sishi said: “Hair loss doesn’t happen overnight; it builds over time. The reality is that 8.6 per cent of children entering the school system in Grade 1 show signs of hair alopecia. By the time they get to [their final year of school], that number has almost tripled—at 21.7 per cent.
“Relaxing hair over time can leave the hair follicles completely damaged because the compounds used cause inflammation of the scalp. Continuous use of relaxers exacerbates this damage.”