Based on the available data, the CIR Expert Panel concluded that ... Calcium Thioglycolate is safe for use in hair straighteners, permanent waves, tonics, dressings, and so forth, wave sets, other non-coloring hair products, and hair dyes and colors, as described in this safety assessment, at concentrations up to 15.2% (as Thioglycolic Acid). Hairdressers should avoid skin contact and minimize consumer skin exposure. Calcium Thioglycolate in depilatories is safe when formulated to be non-irritating under conditions of recommended use.

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