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Ecotoxicological information

Toxicity to microorganisms

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Description of key information

Read-across substance_Phosphoric acid, mono- and di-(C8-C10) ester, compds. with C12 - 14 amine_activated sewage sludge_OECD 209: EC50(30min): 8200 mg/L; EC50(3h): 2100 mg/L; NOEC(3h): 320 mg/L 

Key value for chemical safety assessment

EC50 for microorganisms:
2 100 mg/L
EC10 or NOEC for microorganisms:
320 mg/L

Additional information

No experimental results are available concerning toxicity of the target substance towards sewage treatment microorganisms. Taking into account the valid read-across substance (Phosphoric acid, mono- and di-(C8 -C10) ester, compds. with C12 - 14 amine), this endpoint can be fulfilled. Both substances are mixtures of mono- and di-alkyl phosphates salted with an alkyl amine and possess therefore the same basic structure. For the detailed description and justification, please refer to the separate read-across statement by Chemservice S.A. (2013d).

The toxicity of the read-across substance (Phosphoric acid, mono- and di-(C8 -C10) ester, compds. with C12 - 14 amine) towards sewage treatment plant (STP) microorganisms was investigated according to OECD Guideline 209 (Mead, 1999c). The mixed population of activated sludge microorganisms was sampled from the aeration stage from a predominantly domestic STP. The test solution was prepared by direct dispersion in water. 3,5-dichlorophenol was used as reference substance and confirmed the validity of the test system. Based on results of a range-finding study, the test concentrations for the definitive test were chosen as: 0, 100, 320, 1000, 3200 and 10000 mg/L. The control group was maintained under identical conditions but not exposed to the test substance. Synthetic sewage was added to each test vessel in order to act as respiratory substrate. Dechlorinated tap water passed through an activated carbon filter was used as test water. The hardness was approx. 100 mg/L CaCO3. The rate of respiration was determined after 30 minutes and 3 hours contact time and gave as final results the following values: EC50(30min): 8200 mg/L and EC50(3h): 2100 mg/L. The NOEC was determined to be 320 mg/L. The validation criteria for the control respiration rates and reference material EC50 values have been satisfied. The use of a test temperature of 24 °C as opposed to 20 +/- 2 °C as given in the test guideline was considered to have had no adverse effect on the study or the results obtained.