Pentapotassium bis(peroxymonosulphate) bis(sulphate)

Endpoint summary

Description of key information

The abiotic decomposition in water is fast ultimately forming KHSO4 and H2O2, with the latter being “ready biodegradable”. None of these decomposition products are considered critical with regard to persistence or toxicity. H2O2 is degraded to H2O + O2; KHSO4 is further degraded to form HSO4-/SO42-, ubiquitously present in surface waters and sediments. As H2O2 is not absorpt to sediment and KHSO4 is no risk to the sediment, sediment nor surface water are considered at risk.

Additional information

The environmental fate properties of KMPS triple salt were investigated in hydrolysis studies according to OECD Guideline 111 and a study with synthetic pool water, a degradation in soil study, decomposition studies in activated sludge from sewage treatment plants (STP), an adsorption/desorption study and the calculation of Henry’s law constant. The hydrolysis of KMPS triple salt was investigated in one key study and two supporting studies. The degradation of KMPS triple salt in aqueous solutions is pH and temperature dependent. Degradation is accelerated with increasing temperature and increasing pH. The soil degradation study with KMPS triple salt showed that it decomposes rapidly upon contact with soil. The half-life (DT50) value of KMPS triple salt in soil was conservatively calculated at < 11 minutes. After one hour exposure no measurable KMPS triple salt was present in soil samples. A study using synthetic pool water demonstrated that the decomposition of KMPS triple salt in water is dependent on the presence of oxidisable compounds. The addition of a ‘body fluid analogue’ to the synthetic pool water used in this laboratory test reduced the half-life decomposition of KMPS triple salt from ca. 120 hours (synthetic pool water without ‘body fluid analogue’) to ca. 3 hours. The decomposition studies in activated sludge demonstrated that KMPS triple salt will degrade rapidly if released to a STP. From the results of the available three studies, a geometric mean of 5.12 min at 12 °C was calculated as half-life in activated sludge. For details, please refer to IUCLID 6, section 5.2.2. An adsorption/desorption study following OECD Guideline 121 study was performed to determine the soil adsorption coefficient (Koc) of KMPS triple salt, resulting in a log Koc < 1.25. The calculated log Koc was -3,385 (calculated based on the measured log Pow value). The calculated Henry’s law constant was 2.87E-07 Pa x m³ x mol-1and shows that KMPS triple salt is not volatile.