Ammonium persulfate (APS), a white crystalline solid is the inorganic compound with the formula (NH4)2S2O8. It is highly soluble in water, much more so than the related potassium salt. It is a strong oxidizing agent that is used as a bleaching agent and as a food preservative, also acts as a polymerization initiator in polymer chemistry, as an etchant and cleaner in the manufacture of printed circuit boards, as a booster in hair bleaching formulations in cosmetics and as a polymerization initiator, in soil stabilization and as a gel breaker in enhanced oil recovery systems.
Ammonium persulfate is relatively easy and safe to handle. The Cosmetic Ingredient Review (CIR) Expert Panel has reviewed the use of ammonium persulfate and other persulfates as oxidizing agents in hair colourants and lighteners and has deemed them safe for brief discontinuous use followed by thorough rinsing from the hair and skin. However, it has stated that manufacturers of these products should be aware of the potential for urticarial reactions at concentrations greater than 17.5%.
In a small study of hairdressers, occupational asthma (OA) was found in 51.1% and allergic occupational dermatitis in 36.2% of study participants. Ammonium persulfate was the responsible agent in 87.5% of OA cases. The average overall duration of exposure in the group of hairdressers with OA was 7 years and the average time from start of exposure to onset of symptoms was 5.3 years. Whilst just over 30% had a family history of allergic disease, none of the patients had previous occupations with possible risk factors for asthma, rhinitis, or dermatitis prior to the becoming hairdressers.
Ammonium persulfate is approved for use by the Food and Drug Administration (FDA) as a multipurpose food additive in concentrations less than 0.075%. Although it has been approved for this use in the United States it is currently banned in the European Union, Australia and New Zealand as it has been found to cause contact urticaria in bakers.
Generally ammonium persulfate is safe to use but some people may have an acute allergic reaction. Immediate urticaria after inhalation or contact appears to occur mainly in patients with a history of asthma. It is also evident from the study of hairdressers that repeated exposure may result in increased sensitivity to the substance, and that allergic reactions may not become apparent until after many years of exposure.