Phosphonic acid, monoethyl ester, sodium salt (1:1)

Biodegradation in water and sediment: simulation tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: simulation testing on ultimate degradation in surface water

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

other:

Transformation products:

not measured

Reference 2

Endpoint:

biodegradation in water: sediment simulation testing

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

other:

Transformation products:

not measured

Description of key information

Testing of the ultimate biodegradation in surface water and the sediment simulation testing can be omitted.

Additional information

According to column 2, Annex IX, of the REACH legislation EC 1907/2006, further biotic degradation testing shall be proposed by the registrant if the chemical safety assessment according to Annex I indicates the need to investigate further the degradation of the substance and its degradation products. Based on the high water solubility of the substance (770 g/L at 20 °C and pH 5), the low log Kow (- 2.5 at 20 °C and a pH of 2.5 – 2.6), and the low vapour pressure of the substance (< 1.0 x 10^-5hPa), water is expected to be the main exposure route for this substance in the environment. In order to assess the potential for abiotic degradation, no studies on the hydrolysis are available for the target substance Fosetyl-sodium (CAS 39148-16-8). Therefore, this endpoint is covered by read-across to the analogous substance Fosetyl-aluminium (CAS 39148-24-8). The source substance Fosetyl-aluminium is a long and widely used fungicide. The target substance is a pre-manufacturing product for the synthesis of Fosetyl-aluminium. The study was conducted according to OECD guideline 111 on the hydrolysis of Fosetyl-aluminium. No hydrolysis of Fosetyl-Al was detected after 5 days at 50 °C in pH 4, 7, and 9 solutions. Fosetyl-Al is therefore considered hydrolytically stable. Based on the results with the source substance Fosetyl-Aluminium (CAS 39148-24-8), the target substance Fosetyl-Sodium (CAS 39148-16-8) is also considered to be hydrolytically stable. Thus, abiotic degradation via hydrolysis can be considered negligible for the dissipation of the target substance from the aquatic environment. In order to assess the potential for biotic degradation of Fosetyl-Sodium, a ready biodegradability test is available according to OECD guideline 301D. The results of the test demonstrated that Fosetyl-Sodium is not readily biodegradable (1% biodegradation after 28 days based on ThOD). However, a second study was conducted according to OECD guideline 302C to test for the inherent biodegradability of the test substance. Based on the results of this study Fosetyl-Sodium was observed as inherently biodegradable (86.9% biodegradation after 28 days based on BOD and > 99.9% biodegradation after 28 days based on residue analysis). Therefore, the target substance is not considered persistent in the environment. Based on the aforementioned results, there is no need indicated for further biodegradation testing of the target substance. Thus, the testing of the ultimate biodegradation in surface water and the sediment simulation testing can be omitted.