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Ecotoxicological information

Toxicity to microorganisms

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Description of key information

NOEC = 20 mg/L (result from ready biodegradability test according to OECD 301 F), read-across

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:
20 mg/L

Additional information

No studies investigating the toxicity of sodium ethylparaben (CAS No. 35285 -68 -8) to microorganisms are available. Therefore, toxicity data of the corresponding acid ethylparaben (CAS No. 120 -47 -8) are used as read across.

This read across approach is in accordance with Regulation (EC) No 1907/2006, Annex XI, 1.5. Grouping of substance and read across approach as is explained within the analogue justification in section 13. Except for different cations (hydrogen vs. sodium) the anions of both the source and target substance have identical chemical structures. Since dissociation of the sodium salt under environmental conditions (pH 4 - 9) yields the same ionic species as the acidic form of the substance, this read across can be considered as justified.

For further assessment a ready biodegradability study performed with ethylparaben is used to derive a NOEC for the toxicity to aquatic microorganisms. If a compound degrades well in a ready biodegradability test, or does not inhibit the degradation of a positive control at a certain concentration, this concentration can be used as a NOEC value. This approach is in accordance with the Guidance on information requirements and chemical safety assessment (Chapter R.7b: Endpoint specific guidance, ECHA 2008). The substance was applied at a concentration of 20 mg/L in a ready biodegradability test according to OECD guideline 301 F. Within 28 days, the substance attained 88.4% degradation based on O2 consumption. Therefore, the NOEC for toxicity to aquatic microorganisms is stated as ≥ 20 mg/L.