Author: Vanessa Ngan, Staff Writer, 2007.
Glyceryl monothioglycolate is a chemical substance that is used in permanent wave (perming) solutions. The use of glyceryl monothioglycolate in perming solutions was developed in the 1970s. Known as an acid perm, glyceryl monothioglycolate works by breaking the disulfide links between the polypeptide bonds in the keratin (the protein structure) in the hair wrapped in rods. Heat is applied via a hairdryer and this activates the perm process causing the bonds to reform in the shape of a curl.
Glyceryl monthioglycolate contains no ammonia, hence this type of perm is not associated with the smell that alkaline perms have. In addition, acid perms are gentler to the hair, hence more suitable for delicate or thinner hair.
Clients receiving perms whom are sensitive to glyceryl monothioglycolate may also suffer contact dermatitis on the neck, scalp and ears. Often exposure is much less intense and frequent than in hairdressers, hence the allergy is less commonly found in clients. However, the chemical can remain active in hair shafts for months thus causing long-lasting dermatitis.
Skin patch testing is used to determine glyceryl monothioglycolate sensitisation. Often hairdressers are also sensitive to other chemicals used in hair cosmetics such as paraphenylenediamine (PPD) that is widely used in hair dyes.
In cases of occupational exposure, the only way to prevent contact dermatitis is to avoid contact with glyceryl monothioglycolate. Unfortunately wearing gloves provides little or no protection as patch tests through vinyl gloves showed positive results in glyceryl monothioglycolate sensitised hairdressers.
Your dermatologist may have further specific advice, particularly if you are highly sensitive to glyceryl monothioglycolate.
CAS number: 30618-84-9
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