Subject: Chemical products with KMPS as oxidising agents for swimming pool water
From: "Regulatory UaSolucions" <[email-masked]>
To: <undisclosed-recipients:>
Date: Tue, 2 Sep 2025 12:14:00 +0300

Tähelepanu! Tegemist on väljastpoolt asutust saabunud kirjaga. Tundmatu 
saatja korral palume linke ja faile mitte avada.

Dear Sirs,

We would like to seek clarification regarding the active substance 
trihydrogen pentapotassium di(peroxomonosulfate) di(sulfate) (KMPS) with CAS 
70693-62-8, which has been approved as a biocide for surface disinfection 
and has demonstrated efficacy at 5 g/L.

As outlined in the active substance dossier under the EU Biocidal Products 
Regulation (BPR) for PT2, one of the supported uses is swimming pool 
disinfection, with a minimum in-use concentration of 130 ppm. However, 
according to the declaration provided by LANXESS (active substance 
notifier), additional efficacy studies conducted with Oxone™ (KMPS technical 
grade) demonstrated that the product exhibits no bactericidal activity at 
120 ppm when tested against reference strains in accordance with EN 
1276:2019, modified with the conditions outlined in the OECD guidance 
document.

In line with the Efficacy Guidance under the BPR, EN 1276 constitutes a 
mandatory suspension test at the first tier (phase 2, step 1) to support 
claims related to the reduction of infection risks in swimming pools. Based 
on the results of these tests, LANXESS concluded that at concentrations of 
120 ppm or lower, Oxone™ exhibits solely an oxidising effect and does not 
demonstrate the biocidal activity required to support a disinfection claim 
under the EU BPR.

In practice, this means that at such concentrations, the substance 
contributes only to the oxidation of organic matter (e.g. sweat, body oils, 
and other residues) and the breakdown of nitrogenous compounds. These 
effects help to mitigate odours and improve water clarity, but do not 
provide effective microbial control.

Furthermore, as can be verified on the product labelling (attached), the 
recommended application doses are 1 kg per 50 m³ for the initial treatment 
and 700 g per 50 m³ for weekly maintenance. These correspond to 
concentrations of approximately 20 ppm and 14 ppm, respectively. Such levels 
are far below the concentrations (5 g/l) demonstrated to be necessary to 
achieve a biocidal effect, thereby confirming that the marketed product 
functions solely as an oxidising agent in swimming pool applications.

We kindly request your confirmation of this interpretation, and whether KMPS 
chemical products could be placed on the market as oxidising agents for use 
in swimming pool water in your country, specifically to improve clarity and 
mitigate odours, in compliance with Regulation (EC) No 1907/2006 (REACH) and 
Regulation (EC) No 1272/2008 (CLP).

Your sincerely,

Laia Urdí

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