The hair of black people is elliptical in shape and therefore very tightly curled (Asian hair tends to be round and Caucasian hair is in-between). The relaxer cream breaks down the chemical bonds of the hair shaft, disrupting the elliptical shape and reconstructing the bonds in a different way. Though hair follicles themselves are not damaged, the hair can become very brittle and break off.
Cosmetic products are not subject to pre-market approval by the Food and Drug Administration and a complete list of ingredients is not mandatory, however many brands of hair relaxers list phthalate directly as one of their chemical ingredients. Phthalate from cosmetic products can be inhaled or absorbed by the skin and these have been shown to have estrogenic effects in cell models and experimental animals.