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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:
weight of evidence
Justification for type of information:
REPORTING FORMAT FOR THE ANALOGUE APPROACH
Further information is included in the detailed justification for read-across in the endpoint summary “Aquatic toxicity”.

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
This read-across is based on the hypothesis that source and target substances have similar ecotoxicological properties because they share structural similarities with common functional groups: quaternary amines, esters, and fatty acid chains with comparable length and degree of saturation. Furthermore, they are expected to hydrolyse to a comparable product (amine backbone) and common products (long chain fatty acids). This prediction is supported by ecotoxicological data on the substances themselves.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
Further information is included in the detailed justification for read-across in the endpoint summary “Aquatic toxicity”.

3. ANALOGUE APPROACH JUSTIFICATION
Further information is included in the detailed justification for read-across in the endpoint summary “Aquatic toxicity”.

4. DATA MATRIX
Further information is included in the detailed justification for read-across in the endpoint summary “Aquatic toxicity”.
Reason / purpose for cross-reference:
read-across source
Reason / purpose for cross-reference:
read-across source
Reason / purpose for cross-reference:
read-across: supporting information
Test organisms (species):
Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
0.39 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
0.54 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Remarks on result:
other: 95% ci 0.10-2.9 mg/L
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
1.2 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Remarks on result:
other: 95% ci 0.24-6.0 mg/L
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
0.39 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
act. ingr.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
0.49 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
act. ingr.
Basis for effect:
biomass
Remarks on result:
other: 95% ci 0.22-1.0 mg/L
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
0.95 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
act. ingr.
Basis for effect:
biomass
Remarks on result:
other: 95% ci 0.44-2.1 mg/L
Conclusions:
The NOEC, EC10 and EC50 of MDIPA Esterquat C18 unsatd. to algae in the presence of humic acid based on growth rate were 0.39, 0.54 (95% c.i. 0.10-2.9 mg/L) and 1.2 mg/L (95% c.i. 0.24-6.0 mg/L), respectively.
The NOEC, EC10 and EC50 based on based on yield were 0.39, 0.49 (95% c.i. 0.22-1.0 mg/L) and 0.95 mg/L (95% c.i. 0.44-2.1 mg/L), respectively.

Description of key information

OECD guideline 201, Pseudokirchneriella subcapitata, static, GLP, RL1, in the presence of 4 mg/L humic acid; read across MDIPA Esterquat C18 unsatd
72 h NOEC (growth rate) = 0.39 mg/mL, 72 h ErC10 = 0.54 mg/L (95% c.i. 0.10-2.9 mg/L), 72 h ErC50 = 1.2 mg/L (95% c.i. 0.24-6.0 mg/L);
72 h NOEC (biomass) = 0.39 mg a.i./mL, 72 h EyC10 = 0.49 mg/L (95% c.i. 0.22-1.0 mg/L), 72 h EyC50 = 0.95 mg/L (95% c.i. 0.44-2.1 mg/L)
OECD guideline 201, Pseudokirchneriella subcapitata, static, GLP, RL1, in the presence of 4 mg/L humic acid; read across MDIPA Esterquat C16-18 and 18 unsatd.:
72 h NOEC (growth rate) = 2.7 mg/mL, 72 h ErC10 = 3.2 (95% c.i. 2.5-4.1 mg/L), 72 h ErC50 = 8.1 mg/L (95% c.i. 6.4-10 mg/L);
72 h NOEC (biomass) = 0.91 mg a.i./mL, 72 h EyC10 = 1.3 (95% c.i. 0.45-3.7 mg/L), 72 h EyC50 = 4.4 mg/L (95% c.i. 1.6-12 mg/L)

Key value for chemical safety assessment

EC50 for freshwater algae:
1.2 mg/L
EC10 or NOEC for freshwater algae:
0.54 mg/L

Additional information

In a 96 h algal toxicity study conducted according to a modification of EPA OTS 797.1050 (Algal Toxicity, Tiers I and II),Selenastrum capricornutumwas exposed MDEA-Esterquat C16-18 and C18 unsatd. at nominal concentrations of 0, 2, 4, 8, 16 and 32 mg/L under static conditions. The 96 hr ErC50 value was 2.9 mg/L ( 95% confidence limit <2.0 - 4.2 mg/L; nominal).

This toxicity study is classified as not reliable and does not satisfy the guideline requirements for aquatic toxicity to algae (validity Klimisch 3). Deviations were: no analytical determination of test substance, river water used instead of algal media, and cell counts only done on controls at 0 h timepoint.

However, reliable toxicity studies in freshwater algae are available for the structurally similar source substances MDIPA-Esterquat C16-18 and C18 unsatd. and MDIPA-Esterquat C18 unsatd.. A justification for read-across is given in the general endpoint summary Aquatic toxicity.

In a 72 hour acute toxicity study, the cultures of Pseudokirchneriella subcapitata, strain NIVA CHL 1 were exposed toMDIPA Esterquat C18 unsatd. at nominal concentrations of 0 (control), 0.10, 0.32, 1.0, 3.2 and 10 mg/L, corresponding to measured (TWA) 0.042, 0.14, 0.39, 1.3 and 1.7 mg/L in the presence of 4 mg/L humic acidunder static conditions in accordance with OECD guideline 201 (adopted March 23, 2006; Annex 5 corrected 28 July 2011).

Microscopic observations revealed no abnormalities.

The NOEC, EC10 and EC50 based on growth rate were 0.39, 0.54 (95% c.i. 0.10-2.9 mg/L) and 1.2 mg/L (95% c.i. 0.24-6.0 mg/L), respectively.

The NOEC, EC10 and EC50 based on based on yield were 0.39, 0.49 (95% c.i. 0.22-1.0 mg/L) and 0.95 mg/L (95% c.i. 0.44-2.1 mg/L), respectively.

All effect levels are given based onmeasured (TWA) concentrations.

In a 72 hour acute toxicity study, the cultures of Pseudokirchneriella subcapitata, strain NIVA CHL 1 were exposed to MDIPA-Esterquat C16-18 and C18 unsatd. at nominal concentrations of 0 (control), 0.25, 0.80, 2.5, 8.0 and 25 mg/L, corresponding to measured (TWA) 0.29, 0.91, 2.7, 6.2 and 25 mg/L in the presence of 4 mg/L humic (<2 mg/L DOC) acidunder static conditions in accordance with OECD guideline 201 (adopted March 23, 2006; Annex 5 corrected 28 July 2011).

Microscopic observations revealed no abnormalities.

The NOEC, EC10 and EC50 based on growth rate were 2.7, 3.2 (95% c.i. 2.5-4.1 mg/L) and 8.1 mg/L (95% c.i. 6.4-10 mg/L), respectively.

The NOEC, EC10 and EC50 based on based on yield were 0.91, 1.3 (95% c.i. 0.45-3.7 mg/L) and 4.4 mg/L (95% c.i. 1.6-12 mg/L), respectively.

All effect levels are given based onmeasured (TWA) concentrations.

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