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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Link to relevant study record(s)

Reference
Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Read-across from an analogue substance for which a guideline study (KIimish = 1) is available.
Justification for type of information:
REPORTING FORMAT FOR THE ANALOGUE APPROACH
See attached reporting format and read-across rationale.
Reason / purpose:
read-across source
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
103 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: Based on a read-across from an analogue for which 72h-EC50 = 88 mg/L and 95% CL = 72-100 mg/L
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
37 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: Based on a read-across from an analogue for which 72h-NOEC = 32 mg/L
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
58 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Remarks on result:
other: Based on a read-across from an analogue for which 72h-EC50 = 50 mg/L and 95% CL = 47-55 mg/L
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
37 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Remarks on result:
other: Based on a read-across from an analogue for which 72h-NOEC = 32 mg/L

The data matrix is included in the reporting format attached.

The results from the read-across approach are expressed on the basis of the amount of MPKO generated from the hydrolysis reaction of OS2600 and their molecular weights. The amount of MPKO was estimated using the assumption that 1 mole of the target substance OS2600 produces 3 moles of MPKO. No other adaptions are necessary.

Conclusions:
Based on the read-across approach from the analogue substance MPKO the 72h-EyC50 (biomass) for OS2600 was determined to be 58 mg/L and the ErC50 (growth rate) was 103 mg/L. The NOEC for both biomass and growth rate was 37 mg/L.
Executive summary:

An algae growth inhibition test was performed on the analogue MPKO in accordance with OECD Guideline 201. The EyC50 (biomass) for MPKO was 50 mg/L and the ErC50 (growth rate) was 88 mg/L. The NOEC for both biomass and growth rate was 32 mg/L. Based on these results, the read-across approach was applied and the EyC50 (biomass) for OS2600 was determined to be 58 mg/L and the ErC50 (growth rate) was 103 mg/L. The NOEC for both biomass and growth rate was determined to be 37 mg/L.

Description of key information

Based on the read-across approach from the analogue substance MPKO, the 72h-EyC50 (biomass) of OS 2600 in green algae was determined to be 58 mg/L and the 72h-ErC50 (growth rate) was 103 mg/L. The 72h-NOEC for both biomass and growth rate was determined to be 37 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:
103 mg/L
EC10 or NOEC for freshwater algae:
37 mg/L

Additional information

Key study: Read-across approach from experimental data on the analogue substance MPKO: A study on the freshwater algae (Pseudokirchneriella subcapitata) was performed according to the OECD Guideline 201 (GLP study). Based on the read-across approach from the experimental data on the analogue substance MPKO, the hydrolysis product of OS2600 the EyC50 (biomass) for OS2600 was determined to be 58 mg/L and the ErC50 (growth rate) was 103 mg/L. The NOEC for both biomass and growth rate was determined to be 37 mg/L.