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Environmental fate & pathways

Biodegradation in water and sediment: simulation tests

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biodegradation in water: simulation testing on ultimate degradation in surface water
Data waiving:
other justification
Justification for data waiving:
Justification for type of information:
Simulation testing on ultimate degradation in surface water is part of degradation studies according to Annex IX REACH.

Column 2 of Annex IX states that “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. The choice of the appropriate test(s) depends on the results of the chemical safety assessment and may include simulation testing in appropriate media (e.g. water, sediment or soil).”

Relevant physico-chemical properties of substance were tested with following results.
• Water solubility study results show value 279 g/L.
• Ready biodegradability study shows degradation of substance of 2 % in 28 days. Substance is not readily biodegradable.
• From results of hydrolysis study, the substance is found hydrolytically stable after preliminary test and the half-time of degradation is estimated to be more than 1 year. Therefore, no degradation products of parental substance are expected in water.

Moreover, the substance was tested for effect on biotic organisms with following results:
• Short-term toxicity to fish - Based on no toxicity of the test substance found in preliminary test, the limit test was performed. Results: LC50 (96 h) > 128 mg/L. No toxicity found.
• Short-term toxicity to aquatic invertebrates (Species: Daphnia) – Based on no toxicity of the test substance found in preliminary test, the limit test was performed. Results: EC50 (48 h) > 116 mg/L. No toxicity found.
• Long-term toxicity test on invertebrates (Species: Daphnia) - On the basis of the preliminary test results the definitive test was performed. Results: 21 days – EC50 = 3.2 mg/L, 21 days – NOEC < 1.2 mg/L. No toxicity found.
• Toxicity to aquatic algae and cyanobacteria (Algal Growth Inhibition test) - The 72h - ErC50 > 100 mg/L (50% reduction of) does not suggests specifying the substance as harmful to aquatic organisms.

With regard to available information which show no toxicity to biotic organisms and stability of substance in water environment, there is no need to investigate ultimate degradation of substance in surface water.

Data source

Materials and methods

Test material

Constituent 1
Chemical structure
Reference substance name:
Humic acids, potassium salts
EC Number:
EC Name:
Humic acids, potassium salts
Cas Number:
Molecular formula:
Humic acids, potassium salts

Results and discussion

Transformation products:
not specified

Applicant's summary and conclusion