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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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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
Justification for type of information:
See read-across record in section 13.
Reason / purpose for cross-reference:
read-across source
Reason / purpose for cross-reference:
read-across source
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 6 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Remarks on result:
other:
Remarks:
Result from read-across source substance Cas No. 30798-32-4
Key result
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
3.29 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Remarks on result:
other: 95% C.L.: 2.83 - 3.64
Remarks:
Result from read-across source substance Cas No. 30798-32-4
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
512 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
neutralised
Basis for effect:
growth rate
Remarks on result:
other: pH-values not specified
Remarks:
Result from read-across source substance CAS No. 102-71-6
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
26 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
neutralised
Basis for effect:
growth rate
Remarks on result:
other: pH values not specified
Remarks:
Result from read-across source substance CAS No. 102-71-6

Description of key information

Results for the toxicity to aquatic algae and cyanobacteria of the substance (CAS no. 29340-81-6), were based on results of the dissociation product CAS no. 29340-81-6, namely triethanolamine (TEA, CAS no. 102-71-6) and structural analogue 2-hydroxypropyl)ammonium citrate (MIPA citrate; CAS no. 30798-32-4). The 72-h ErC50 value and the 72-h ErC10 for TEA in Desmodesmus subspicatus are 512 and 26 mg/L respectively. The 72-h ErC50 value and the 72-h ErC10 for MIPA citrate in Pseudokirchneriella subcapitata are >6 and 3.29 mg a.i./L, respectively. The values of >6 and 3.29 mg a.i./L will be used in the assessment.

Key value for chemical safety assessment

EC50 for freshwater algae:
6 mg/L
EC10 or NOEC for freshwater algae:
3.29 mg/L

Additional information

No substance-specific data on the toxicity to aquatic algae and cyanobacteria of the substance (CAS 29340-81-6) are available. However, according to Article 13 of legislation EC1907/2006, in case no appropriate animal studies are available for assessment, information should be generated whenever possible by means other than vertebrate animal tests, i. e. applying alternative methods such as in vitro tests, QSARs, grouping and read-across. CAS 29340-81-6 is an organic compound manufactured from triethanolamine (TEA, CAS 102-71-6) and citric acid (CAS 77-92-9) and dissociates into the respective TEA cation and citrate anion. Therefore it is considered to be acceptable to derive lacking information on toxicological properties of CAS 29340-81-6 by read-across from TEA and close analogue 2-hydroxypropyl)ammonium citrate (MIPA citrate; CAS no. 30798-32-4), which dissociates into citric acid in water.

For TEA, the short-term toxicity to aquatic algae was determined in a study according to DIN 38412, part 9 (draft) (Amann et al., 1989). In this study, freshwater species Desmodesmus subspicatus were exposed for 72 hours to the test substance (concentration not documented) under static conditions. The test was performed with neutralised and not neutralised test medium in parallel. The effect data were evaluated based on growth rate. For the risk assessment the effect data for the neutralised test medium was used. The 72-h ErC50 of this test was determined to be 512 mg/L. The 72-h ErC10 value was determined to be 26 mg/L.

For MIPA citrate, the toxicity towards freshwater algae was determined in a study according to OECD TG 201 and in compliance with GLP criteria (Ibacon, 2017) .In this study, exponentially growing freshwater algae (Pseudokirchneriella subcapitata) were exposed to nominal test substance concentrations of 0 (control), 1.3, 4.2, 13.3, 42.1 and 133 mg test item/L for 72 hours under static conditions. The test material as such exists as aqueous solution. The test material concentration corresponds to a nominal concentration of 1, 3.2, 10, 31.6 and 100 mg/L based on active ingredient (a.i.). Test concentrations were analytically verified and the geometric mean measured concentrations were determined to be <LOD, (control), 0.483, 0.632, 1.7, 3.3 and 6 mg a.i./L (corresponding to 0.719, 0.94, 2.53, 4.91 and 8.93 mg test item/L). Since the test item concentrations were not within ± 20% of the nominal concentrations during the test, all reported results refer to geometric mean concentrations. At the start of the test and after 24, 48 and 72 hours exposure duration, the algae were scored for number of cells and for microscopic abnormalities. At concentrations of nominal 10, 31.6 and 100 mg a.i./L, significant inhibition in yield and growth rate was observed at the end of the study. After 72 hours exposure, yield was inhibited for 14.6%, 40.8% and 83% and growth rate was inhibited for 3.1%, 9.0% and 30.4% test concentrations of 10, 31.6 and 100 mg a.i./L, respectively. Based on these findings, the 72-h EC50 values for growth rate and yield are determined at > 6 mg a.i./L and 3.5 mg a.i./L, respectively. The 72-h EC10 values for growth rate and yield are determined at 3.29 mg a.i./L and 1.47 mg a.i./L.

As a worst-case approach, the 72-h ErC50 and 72-h ErC10 values of 6 and 3.29 mg/L is used in the derivation of PNECs of TEA citrate.